Radiol Oncol 2020; 54(4): 429-436. doi: 10.2478/raon-2020-0057
429
research article
The influence of genetic variability in IL1B and 
MIR146A on the risk of pleural plaques and 
malignant mesothelioma
Petra Piber1, Neza Vavpetic1, Katja Goricar2, Vita Dolzan2, Viljem Kovac1,3, Alenka Franko1,4
1 Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
2 Pharmacogenetics Laboratory, Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
3 Institute of Oncology Ljubljana, Ljubljana, Slovenia
4 Clinical Institute of Occupational Medicine, University Medical Centre Ljubljana, Ljubljana, Slovenia
Radiol Oncol 2020; 54(4): 429-436.
Received 7 July 2020
Accepted 6 August 2020
Correspondence to: Assoc. Prof. Alenka Franko, M.D., Ph.D., Clinical Institute of Occupational Medicine, University Medical Centre Ljubljana, 
Poljanski nasip 58, SI-1000 Ljubljana, Slovenia. Email: alenka.franko@siol.net
Petra Piber and Neza Vavpetic contributed equally.
Disclosure: No potential conflict of interest were disclosed.
Background. Asbestos exposure is associated with the development of pleural plaques as well as malignant meso-
thelioma (MM). Asbestos fibres activate macrophages, leading to the release of inflammatory mediators including 
interleukin 1 beta (IL-1β). The expression of IL-1β may be influenced by genetic variability of IL1B gene or regulatory 
microRNAs (miRNAs). This study investigated the effect of polymorphisms in IL1B and MIR146A genes on the risk of 
developing pleural plaques and MM.
Subjects and methods. In total, 394 patients with pleural plaques, 277 patients with MM, and 175 healthy control 
subjects were genotyped for IL1B and MIR146A polymorphisms. Logistic regression was used in statistical analysis.
Results. We found no association between MIR146A and IL1B genotypes, and the risk of pleural plaques. MIR146A 
rs2910164 was significantly associated with a decreased risk of MM (OR = 0.31, 95% CI = 0.13–0.73, p = 0.008). Carriers 
of two polymorphic alleles had a lower risk of developing MM, even after adjustment for gender and age (OR = 0.34, 
95% CI = 0.14–0.85, p = 0.020). Among patients with known asbestos exposure, carriers of at least one polymorphic IL1B 
rs1143623 allele also had a lower risk of MM in multivariable analysis (OR = 0.50, 95% CI = 0.28–0.92, p = 0.025). The inter-
action between IL1B rs1143623 and IL1B rs1071676 was significantly associated with an increased risk of MM (p = 0.050).
Conclusions. Our findings suggest that genetic variability of inflammatory mediator IL-1β could contribute to the risk 
of developing MM, but not pleural plaques.
Key words: asbestos; genetic variation; malignant mesothelioma; miRNA; pleural plaques
Introduction
Asbestos exposure is related to several pleural 
diseases, such as pleural plaques, diffuse pleu-
ral thickenings, pleural effusions and malignant 
mesothelioma (MM). MM is an aggressive form of 
cancer found on the mesothelium, generally on the 
pleura (65%), peritoneum (30%) or other serosal 
membranes (1%).1,2
MM is often diagnosed in its later stages, is 
rarely operable and can respond poorly to con-
ventional chemotherapy.3 Clinical signs and 
symptoms are uncharacteristic and reminiscent 
of many other pulmonary diseases. Patients often 
experience dyspnea, chest pain, weight loss and fa-
tigue. Only a small proportion of MM patients are 
asymptomatic at the time of diagnosis.2,4 Average 
life expectancy is around 7 months with support 
Radiol Oncol 2020; 54(4): 429-436.
Piber et al. / IL1B and MIR146A SNPs in malignant mesothelioma430
therapy and 12 months with chemotherapy.5 MM 
most often occurs in patients older than 65 years.2,6 
Epidemiological studies have shown that the main 
cause of MM is asbestos exposure, with the inci-
dence of this cancer still increasing due to the long 
latent period.7 Genetic factors have also been sug-
gested to influence the development of MM; pa-
tients often have mutations in tumour suppressor 
genes, such as BAP1, CDKN2A and NF2.8,9 
Along with MM, asbestos exposure is also 
related to the development of pleural plaques. 
Pleural plaques are white and yellow thicken-
ings of pleura, often asymmetrical and bilateral. 
Histologically, they are acellular, composed of 
hyalinised collagen, which is covered by one lay-
er of mesothelial cells. Half of the patients with 
a history of asbestos exposure develop pleural 
plaques, typically 20 to 30 years after exposure. 
The risk of pleural plaques rises with the length of 
asbestos exposure.10 It has been proposed that in-
flammation caused by asbestos is involved in the 
pathogenesis of both pleural plaques and MM.3,11 
Asbestos fibres are known to trigger the release 
of inflammatory mediators, which leads to the 
downregulation of apoptosis.3
After inhalation, asbestos fibres reach pleural 
space and are deposited in mesothelial cells.12 This 
leads to local inflammatory response and prolif-
eration of mesothelial cells. In vitro studies have 
shown that the fibres induce inflammation and ap-
optosis and most of the tissue damage is related to 
elevated interleukin 1 beta (IL-1β).3 Macrophages 
accumulate near asbestos deposits and release cy-
tokines, such as IL-1β and tumour necrosis factor 
alpha (TNF-α).8
In response to asbestos, an intrinsic inflamma-
tory mechanism triggers inflammation via inflam-
masome NLRP3, which is NLR family pyrin do-
main containing 3, activated by danger-associated 
molecular patterns (DAMP) or pathogen-associat-
ed molecular patterns (PAMP).13,14 NLRP3 inflam-
masome is a protein complex of NLRP3, apoptosis-
associated speck-like protein (ASC) and caspase-1, 
found in macrophages, which triggers a type of 
apoptosis, known as piroptosis.11,13,15 The activation 
of NLRP3 inflammasome increases the production 
of IL-1β from its precursor, mediated by caspase-1 
and pro-inflammatory mediators from macrophag-
es.8,15,16 IL-1β, coded by IL1B gene, is an inflamma-
tory mediator, found during chronic inflammation 
and a key player in carcinogenesis.17,18 It promotes 
neutrophil recruitment and transcription of NF-κB 
(nuclear factor kappa B), the latter being known to 
influence tumour growth and response to chemo-
therapy.18 In vitro studies showed that IL-1β plays 
an important part in increasing proliferation, lead-
ing to a malignant transformation.8
IL-1β release can also be regulated by miRNAs, 
21-23 nucleotides long non-coding RNAs, which 
inhibit translation by binding to the 3′-untrans-
lated region (3′-UTR) of mRNA.19 miRNAs are 
involved in networks of gene regulation and their 
expression often changes in cancerous tissue, in-
cluding MM.20-25 A key miRNA, influencing the ex-
pression of IL1B, is miRNA-146. Two human vari-
ants are found; miRNA-146a and miRNA-146b, 
both assumed to play a role in toll-like receptor 
(TLR) based signalling and cytokine response.21,22,26 
Previous studies found that miRNA-146a has an 
anti-inflammatory function, with its silencing lead-
ing to an increase in IL-1 and its induction having 
the opposite effect.22,26,27
Genetic factors, such as single nucleotide poly-
morphisms (SNPs), may influence protein ex-
pression.17,28,29 IL1B rs16944 (c.-511C>T), located 
in 5’ untranslated region (UTR), influences the 
binding of transcription factors.30 Higher levels of 
IL-1β were found in homozygotes with polymor-
phic allele, leading to a higher risk of developing 
chronic inflammation-related diseases, such as 
diabetes mellitus type 2 and breast cancer.31,32 IL1B 
rs1143623 (-1464G>C) is also located in 5’ UTR and 
affects the binding of transcription factors.30 Its 
polymorphic C allele was associated with a lower 
risk of developing lung and colorectal carcinoma, 
due to a lower production and release of IL-1β.28,29 
The relationship between IL1B rs1071676, located 
in 3’UTR, and carcinogenesis has not yet been es-
tablished, but as it affects miRNA binding site, it 
could also influence IL1B expression. SNPs have 
also been found in genes coding for miRNAs, such 
as MIR146A rs2910164, which has been related to 
both higher33 and lower risks34 of malignant trans-
formations, according to previous research.35
To the best of our knowledge, the role of IL1B 
and MIR146A genetic variability in the develop-
ment of asbestos-related diseases has not been 
evaluated so far. The aim of the present study was 
therefore to evaluate the influence of IL1B and 
MIR146A polymorphisms on the risk of develop-
ing pleural plaques and MM.
Subjects and methods
Subjects
The retrospective case-control study included 
277 patients with histologically confirmed pleu-
Radiol Oncol 2020; 54(4): 429-436.
Piber et al. / IL1B and MIR146A SNPs in malignant mesothelioma 431
ral or peritoneal MM, treated at the Institute of 
Oncology Ljubljana between 1 January 2001 and 30 
September 2018, 394 patients with pleural plaques 
and 175 healthy control subjects, all of whom were 
previously exposed to asbestos. The control group 
and those with pleural plaques were occupation-
ally exposed to asbestos by working in the factory 
Salonit Anhovo, Slovenia, and were presented at 
the State Board for the Recognition of Occupational 
Asbestos Diseases between January 1999 and 
December 2003. In 2018, the subjects from the con-
trol group were found not to have any asbestos-
related disease. 
The study was approved by the Slovenian Ethics 
Committee for Research in Medicine and was car-
ried out according to the Declaration of Helsinki. 
Clinical diagnosis
Patients with pleural plaques have been diagnosed 
based on X-ray and high-resolution computed to-
mography (HRCT), while MM diagnosis was con-
firmed by a pathologist based on the histopathol-
ogy of samples gathered thoracoscopically in the 
case of the pleural and laparoscopically in the case 
of the peritoneal type of MM.2,36,37
Asbestos exposure and smoking
A semiquantative method was used to assess the 
asbestos exposure. The data on cumulative asbes-
tos exposure expressed in fibres/cm3-years were 
available for all control subjects, all subjects with 
pleural plaques except for 6, and for 40 subjects 
with MM. Based on these data, the asbestos expo-
sure in these subjects was categorised into three 
groups: low (< 11 fibres/cm3-years), medium (11–20 
fibres/cm3-years) and high (> 20 fibres/cm3-years) 
asbestos exposure. For additional 49 subjects with 
MM who lacked the data on cumulative asbestos 
exposure a thorough work history was obtained 
by an interview performed by a single expert ex-
perienced in asbestos exposure assessment. Their 
exposures were compared with the exposures from 
the group of patients with known cumulative as-
bestos exposure and were categorized accordingly 
into three groups with presumed low, medium 
and high asbestos exposure.2 For the remaining 188 
MM patients, exact data on asbestos exposure were 
not available.
An interview based on a standardized question-
naire was conducted with the control group and 
patients with pleural plaques to collect data on 
smoking, while the medical documentation of the 
Institute of Oncology of Ljubljana was used to ob-
tain this piece of data for patients with MM.2,38
Single nucleotide polymorphism (SNP) 
selection
Using LD Tag SNP Selection,30 dbSNP,39 Ensembl40 
and LDlink41 we identified IL1B SNPs, which had 
the minor allele frequency (MAF) greater than 
0.05 in the European population, could influence 
the expression of IL1B and were located less than 
5000 base pairs up- or downstream from the gene. 
Polymorphism rs1071676, located in 3’UTR as well 
as rs16944 and rs1146323, located in 5’UTR matched 
our criteria. Based on miRDB,42 miRTarBase43 and 
Variation Viewer we identified miRNAs, that could 
influence IL1B expression and SNPs in the genes 
coding for these miRNAs. Based on the inclusion cri-
teria, we selected rs2910164, a SNP in miRNA-146a.
Molecular genetic analysis
We isolated DNA from venous blood of 44 pa-
tients with MM using E.Z.N.A.® SQ II Blood DNA 
Kit (Omega Bio-tek, Inc., Norcross, Georgia, USA) 
following the manufacturer’s instructions. DNA 
samples of all other subjects had been isolated dur-
ing previous studies.44 Genotyping was performed 
using competitive allele-specific PCR (KASP), the 
KASP Master mix (LGC, Middlesex, UK) and cus-
tom KASP Genotyping Assay (LGC, Middlesex, 
UK) according to the manufacturer’s instructions.
Statistics
Median and interquartile range were used to de-
scribe continuous variables, while frequencies 
were used for categorical variables. To compare 
the distribution of categorical variables, Fisher’s 
exact test was performed, while non-parametric 
Kruskal-Wallis test was used for continuous vari-
ables. Deviation from the Hardy-Weinberg equilib-
rium (HWE) was evaluated using chi-square test. 
Both additive and dominant genetic models were 
used in statistical analyses. Univariable and mul-
tivariable logistic regression was used to analyse 
the association between genotypes and asbestos-
related diseases (pleural plaques and MM). For 
the analysis of multiplicative interactions between 
genotypes, logistic regression models using dum-
my variables were used. All statistical analyses 
were performed using the Statistical Package for 
the Social Sciences (SPSS) for Windows, version 
21.0 (IBM Corporation, Armonk, NY, USA).
Radiol Oncol 2020; 54(4): 429-436.
Piber et al. / IL1B and MIR146A SNPs in malignant mesothelioma432
Results 
Characteristics of patients with MM and pleural 
plaques as well as the control group are shown 
in Table 1. There was a statistically significant dif-
ference between the groups in respect to age (p 
< 0.001) and asbestos exposure (p < 0.001). MM 
patients were significantly older than the control 
group or patients with pleural plaques. Among the 
subjects with known asbestos exposure, 51.7% of 
patients with MM had medium or high exposure 
compared to 23.4% of the control group and 28.4 
% of patients with pleural plaques. There was no 
statistically significant difference between groups 
regarding gender (p = 0.410) and smoking status (p 
= 0.267) (Table 1). 
A further analysis of asbestos exposure showed 
that medium and high levels of asbestos exposure 
were associated with an increased risk of MM com-
pared both to the control group (odds ratio [OR] = 
3.50; 95% confidence interval [CI] = 2.03–6.02; p < 
0.001) and patients with pleural plaques (OR = 2.70; 
95% CI = 1.69–4.33; p < 0.001). 
Among the patients with MM, 19 (6.9 %) had 
stage I MM, 61 (22.1 %) were in stage II of the dis-
ease, 83 (30.1 %) had stage III and 81 (29.3 %) stage 
IV MM. Thirty-two patients (11.6 %) had the peri-
toneal subtype of MM, where stage was not deter-
mined and in one patient, the MM stage could not 
be determined. In our cohort, the most prevalent 
histological subtype of MM was the epithelioid 
subtype (206; 74.4 %); however some of the patients 
had either the biphasic (26; 9.4 %) or sarcomatoid 
subtype (26; 9.4 %) and in the case of a few patients 
(19; 6.6 %), the histological subtype was not deter-
mined.
A comparison of patients with pleural plaques 
and healthy controls revealed no statistically sig-
nificant influence on the risk of pleural plaques 
for any of the selected polymorphisms, neither in 
univariable analysis nor after adjustments for age, 
gender and asbestos exposure (Supplementary 
Table 1).
The analysis of the association between genetic 
polymorphisms and MM has shown statistically 
significant influence of polymorphism MIR146A 
rs2910164 on the risk of developing MM. Carriers 
of two polymorphic alleles (genotype CC) had a 
lower risk of developing MM (OR = 0.31; 95% CI 
= 0.13–0.73; p = 0.008). There was no influence of 
other genetic polymorphisms on the development 
of MM (Table 2). 
In multivariable analysis, polymorphism 
MIR146A rs2910164 remained associated with a 
decreased risk of developing MM after adjustment 
for age and gender (OR = 0.34; 95% CI = 0.14–0.85; 
p = 0.020). However, in the subgroup with asbestos 
exposure data, MIR146A rs2910164 polymorphism 
no longer showed statistically significant influence 
on the risk of MM after adjustment for age, gender 
and asbestos exposure (OR = 0.39; 95% CI = 0.11–
1.38; p = 0.144) (Table 2). Carriers of at least one 
polymorphic IL1B rs1143623 (genotype GC or CC) 
showed a significantly decreased risk of MM after 
adjustment for age, gender and asbestos exposure 
(OR = 0.50; 95% CI = 0.28–0.92; p = 0.025) (Table 2).
A comparison of patients with MM and pleu-
ral plaques showed that polymorphism MIR146A 
rs2910164 was statistically significantly associated 
with the risk of the development of MM compared 
to pleural plaques (Table 3). Patients that had two 
polymorphic MIR146A rs2910164 alleles (geno-
TABLE 1. Characteristics of subjects included in the study
Characteristics Control groupN = 175
Pleural plaques
N = 394
Malignant 
mesothelioma
N = 277
Test p
Gender
Male, N (%) 119 (68.0) 271 (68.8) 202 (72.9) 1.757a 0.410
Female, N (%) 56 (32.0) 123 (31.3) 75 (27.1)
Age Median (25%–75%) 55.3 (48.6–63.7) 54.9 (48.8–62.7) 66.0 (59.0–73.0) 151.666b < 0.001
Asbestos exposure
Low, N (%) 134 (76.6) 278 (71.6) [6] 43 (48.3) [188] 26.891a < 0.001
Medium, N (%) 13 (7.4) 41 (10.6) 24 (27.0)
High, N (%) 28 (16.0) 69 (17.8) 22 (24.7)
Smoking
No, N (%) 94 (53.7) 194 (49.4) [1] 150 (55.6) [7] 2.640a 0.267
Yes, N (%) 81 (46.3) 199 (50.6) 120 (44.4)
a calculated using Fisher exact test; b calculated using Kruskal-Wallis test; number of missing data is presented in [] brackets
Radiol Oncol 2020; 54(4): 429-436.
Piber et al. / IL1B and MIR146A SNPs in malignant mesothelioma 433
TABLE 2. Association between selected polymorphisms and the risk of developing malignant mesothelioma
SNP Genotype ControlsN (%)
MM
N (%) OR (95% CI) p OR (95% CI)adj1 padj1 OR (95% CI)adj2 padj2
IL1B rs1143623
GG 88 (50.3) 152 (54.9) reference reference  
GC 67 (38.3) 97 (35.0) 0.84 (0.56–1.26) 0.396 0.82 (0.52–1.29) 0.388 0.56 (0.29–1.05) 0.072
CC 20 (11.4) 28 (10.1) 0.81 (0.43–1.52) 0.514 0.69 (0.35–1.38) 0.294 0.34 (0.11–1.04) 0.060
GC+CC 87 (49.7) 125 (45.1) 0.83 (0.57–1.22) 0.341 0.79 (0.52–1.20) 0.266 0.50 (0.28–0.92) 0.025
IL1B rs16944
TT 21 (12.0) 36 (13.0) 1.10 (0.60–2.02) 0.756 0.94 (0.48–1.82) 0.849 0.53 (0.20–1.43) 0.210
TC 75 (42.9) 118 (42.6) 1.01 (0.67–1.51) 0.960 0.98 (0.63–1.52) 0.911 0.67 (0.36–1.24) 0.198
CC 79 (45.1) 123 (44.4) reference reference  
TC+TT 96 (54.9) 154 (55.6) 1.03 (0.70–1.51) 0.878 0.97 (0.64–1.47) 0.873 0.63 (0.35–1.13) 0.122
IL1B rs1071676
GG 105 (60.0) 165 (59.6) reference reference  
GC 60 (34.3) 98 (35.4) 1.04 (0.69–1.56) 0.851 0.97 (0.62–1.51) 0.895 1.00 (0.53–1.89) 0.993
CC 10 (5.7) 14 (5.1) 0.89 (0.38–2.08) 0.789 0.96 (0.38–2.41) 0.931 2.03 (0.70–5.90) 0.194
GC+CC 70 (40.0) 112 (40.4) 1.02 (0.69–1.50) 0.927 0.97 (0.64–1.48) 0.885 1.15 (0.64–2.08) 0.632
MIR146A 
rs2910164
GG 94 (53.7) 158 (57.0) reference reference
GC 64 (36.6) 110 (39.7) 1.02 (0.69–1.53) 0.913 0.91 (0.59–1.41) 0.672 0.67 (0.36–1.25) 0.209
CC 17 (9.7) 9 (3.2) 0.31 (0.13–0.73) 0.008 0.34 (0.14–0.85) 0.020 0.39 (0.11–1.38) 0.144
GC+CC 81 (46.3) 119 (43.0) 0.87 (0.60–1.28) 0.488 0.79 (0.52–1.21) 0.278 0.62 (0.34–1.11) 0.109
adj1 = adjustment for age and gender; adj2 = adjustment for age, gender and asbestos exposure; CI = confidence interval; MM = malignant mesothelioma;  OR = odds ratio; 
SNP = single nucleotide polymorphism
TABLE 3. Association between selected polymorphisms and the risk of developing malignant mesothelioma compared to pleural plaques
SNP Genotype
Pleural 
plaques
N (%)
MM
N (%) OR (95 % CI) p OR (95 % CI)adj1 padj1 OR (95 % CI)adj2 padj2
IL1B rs1143623
GG 205 (52.0) 152 (54.9) reference reference  
GC 157 (39.8) 97 (35.0) 0.83 (0.60–1.16) 0.277 0.88 (0.61–1.27) 0.499 0.67 (0.39–1.15) 0.151
CC 32 (8.1) 28 (10.1) 1.18 (0.68–2.04) 0.554 1.07 (0.58–1.99) 0.827 0.65 (0.22–1.86) 0.418
GC+CC 189 (48.0) 125 (45.1) 0.89 (0.66–1.21) 0.467 0.92 (0.65–1.29) 0.617 0.67 (0.40–1.11) 0.123
IL1B rs16944
TT 50 (12.7) 36 (13.0) 1.02 (0.63–1.67) 0.923 0.96 (0.56–1.67) 0.897 0.54 (0.22–1.34) 0.184
TC 169 (42.9) 118 (42.6) 0.99 (0.71–1.38) 0.969 0.98 (0.68–1.42) 0.929 0.70 (0.41–1.19) 0.186
CC 175 (44.4) 123 (44.4) reference reference  
TC+TT 219 (55.6) 154 (55.6) 1.00 (0.73–1.36) 0.998 0.98 (0.69–1.38) 0.905 0.66 (0.40–1.10) 0.110
IL1B rs1071676
GG 233 (59.1) 165 (59.6) reference reference
GC 145 (36.8) 98 (35.4) 0.95 (0.69–1.32) 0.778 0.93 (0.65–1.34) 0.708 0.92 (0.53–1.60) 0.774
CC 16 (4.1) 14 (5.1) 1.24 (0.59–2.60) 0.578 1.29 (0.56–2.97) 0.553 2.83 (1.04–7.71) 0.042
GC+CC 161 (40.9) 112 (40.4) 0.98 (0.72–1.34) 0.911 0.97 (0.68–1.37) 0.849 1.09 (0.66–1.82) 0.731
MIR146A 
rs2910164
GG 196 (49.7) 158 (57.0) reference reference  
GC 163 (41.4) 110 (39.7) 0.84 (0.61–1.15) 0.276 0.84 (0.58–1.20) 0.326 0.65 (0.38–1.11) 0.118
CC 35 (8.9) 9 (3.2) 0.32 (0.15–0.68) 0.003 0.33 (0.15–0.75) 0.008 0.34 (0.11–1.09) 0.069
GC+CC 198 (50.3) 119 (43.0) 0.75 (0.55–1.02) 0.063 0.74 (0.53–1.05) 0.092 0.59 (0.36–0.99) 0.046
adj1 = adjustment for age and gender; adj2 = adjustment for age, gender and asbestos exposure; CI = confidence interval; MM = malignant mesothelioma;  OR = odds ratio; 
SNP = single nucleotide polymorphism
Radiol Oncol 2020; 54(4): 429-436.
Piber et al. / IL1B and MIR146A SNPs in malignant mesothelioma434
type CC) had a significantly decreased risk of MM 
compared to pleural plaques (OR = 0.32; 95% CI = 
0.15–0.68; p = 0.003). Similarly, after adjustment for 
gender and age, patients who were homozygotes 
for polymorphic MIR146A rs2910164 still showed 
a lower risk of developing MM (OR = 0.33; 95% CI 
= 0.15–0.75; p = 0.008). In the subgroup with avail-
able asbestos exposure data, MIR146A rs2910164 
was significantly associated with a decreased MM 
risk only in the dominant model (OR = 0.59; 95% 
CI = 0.36–0.99; p = 0.046) (Table 3). Additionally, 
patients that were homozygotes for the IL1B 
rs1071676 polymorphism (CC genotype) had an 
increased risk of developing MM when patients 
with pleural plaques were used as a control group 
and the analysis was adjusted for age, gender and 
asbestos exposure (OR = 2.83; 95% CI = 1.04–7.71; p 
= 0.042) (Table 3).
In further logistic regression modelling, the in-
teractions between polymorphisms showed no 
significant influence on the risk of pleural plaques 
(data not shown). The analysis of the influence of 
the interaction between IL1B rs1143623 and IL1B 
rs1071676 polymorphisms showed significant in-
fluence on the increased MM risk (OR = 2.24, 95% 
CI = 1.00–5.00, p = 0.050). No other interactions 
between polymorphisms had a statistically signifi-
cant influence on the risk of MM (Supplementary 
Table 2).
Discussion 
The association between MM and asbestos expo-
sure has first been described in 1960 and, although 
very few genetic factors have been studied, multi-
ple factors have since then been considered to in-
fluence the pathogenesis of MM.45 In the present 
study, we evaluated the effect of polymorphisms 
of IL-1β and miRNA-146a genes on the risk of de-
veloping MM and pleural plaques. The key finding 
of the present study was the association between 
MIR146A rs2910164 and lower risk of the develop-
ment of MM.
Consistent with the previous studies, the aver-
age age of MM patients was found to be higher than 
that of the patients with pleural plaques or the con-
trol group, probably due to the long latency period 
between the first asbestos exposure and MM.2,6,44 
Our study showed no significant association be-
tween smoking and MM, which is in agreement 
with previous findings.2,44,46 Subjects with high or 
medium exposure to asbestos had a higher risk of 
developing MM, compared to the group with pleu-
ral plaques or the control group. Regardless of that, 
almost half (48.3%) of MM patients were exposed 
to low levels of asbestos, which is consistent with 
previous studies claiming there is no threshold lev-
el for the development of MM.47,48
It is not yet clear to what an extent the pleural 
plaques present a risk factor for MM. The studies 
performed so far suggested that pleural plaques 
are more a sign of asbestos exposure, than a carci-
nogenic factor.49,50 This hypothesis is in agreement 
with the findings of this study as the genotype 
frequency distribution of patients with pleural 
plaques was found to be more similar to that of the 
control group, rather than the genotype frequency 
distribution of patients with MM. 
Compared to both the control group and the 
patients with pleural plaques, homozygotes with 
polymorphic MIR146A rs2910164 C allele were at 
a lower risk of developing MM, even after adjust-
ment for age and gender. In the subgroup of pa-
tients with known asbestos exposure, carriers of at 
least one polymorphic MIR146A rs2910164 allele 
had a lower risk of MM in comparison to patients 
with pleural plaques. 
According to our knowledge, the relation be-
tween MIR146A rs2910164 and MM has not yet 
been studied, but the polymorphism itself has 
already been associated with several other malig-
nant diseases. Previous studies suggested that the 
polymorphic allele C had a protective function in 
the oncogenesis of melanoma51 and non-small cell 
lung carcinoma33, while the same was found for the 
G allele in case of papillary thyroid tumour.52 The 
association of rs2910164 with the pathogenesis of 
MM could be explained with its influence in miR-
NA expression: CC genotype was previously as-
sociated with a greater production of miRNA-146a 
in cancerous tissue.53-55 Increased expression of 
miRNA-146a in turn leads to the suppression of in-
flammatory pathways, reducing the expression of 
proinflammatory cytokines IL-1, IL-6 and TNFα,56 
while miRNA-146a inhibition has been shown to 
increase production of those cytokines, resulting 
in greater inflammatory response to asbestos, pro-
moting carcinogenesis and increasing the risk of 
MM.17,18 The role and expression of miRNA-146a 
in carcinogenesis is still unclear, as some studies 
found the levels of miRNA-146a to be decreased in 
cancerous tissue of the lung57 and stomach carci-
noma,58 while other studies found increased levels 
in the cases of melanoma,51 cervical cancer59 and 
papillary thyroid cancer.52 It is possible that miR-
NA-146a has a tissue-specific function, so further 
studies are required.
Radiol Oncol 2020; 54(4): 429-436.
Piber et al. / IL1B and MIR146A SNPs in malignant mesothelioma 435
Another important finding of this study has 
been the association between the polymorphic 
IL1B rs1143623 allele and a lower risk of develop-
ing MM. In the subgroup of subjects with known 
asbestos exposure, subjects with at least one poly-
morphic C allele had a lower risk of developing 
MM compared to the control group. IL1B rs1143623 
is located at the biding site of the transcription 
factors and can lower the expression of IL1B.30,39 
Lower levels of IL-1β result in a less intensive in-
flammatory reaction caused by the asbestos fibres, 
which could have a protective effect. The former is 
in agreement with the studies that showed subjects 
with one polymorphic C allele having a lower risk 
of developing lung cancer28 and homozygotes for 
the polymorphic C allele having a lower risk of de-
veloping colorectal cancer.29
Finally, this study has shown that the interac-
tion between IL1B rs1143623 and IL1B rs1071676 is 
associated with a higher risk of developing MM, 
even though IL1B rs1071676 independently had no 
effect on the risk of MM, while IL1B rs1143623 was 
associated with a lower risk of MM within the sub-
group of subjects with known asbestos exposure. 
IL1B rs1143623 was associated with a lower risk 
of MM only among carriers of two wild type IL1B 
rs1071676 alleles. As IL1B rs1143623 can influence 
the binding of transcription factors and rs1071676 
can influence the binding of miRNA, the interac-
tion of both polymorphisms could result in a great-
er expression of IL-1β, however this has not been 
studied yet.30 Further studies are needed to explain 
the role of IL1B rs1143623 and its interactions with 
other polymorphisms and environmental factors 
in MM.
Lack of asbestos exposure information for all 
the subjects has been identified as the limitation of 
our study. Therefore, the subgroup for which as-
bestos exposure has been taken into consideration, 
was smaller than the overall sample. This could 
account for the discrepancy between the results of 
the analysis adjusted for asbestos exposure and the 
results of the analysis that did not take asbestos ex-
posure into account. The strength of this study is 
its large sample size. To the best of our knowledge, 
this is also the first study researching the effect of 
IL1B and MIR146A polymorphisms on the risk of 
developing MM.
In conclusion, our results suggest that IL1B and 
MIR146A polymorphisms may contribute to the 
risk of MM development. Further studies, possibly 
evaluating serum or tissue protein expression, are 
needed to confirm these associations in independ-
ent patient cohorts and elucidate the role of IL-1 
and miRNA-146a in the development of asbestos-
related diseases.
 Acknowledgements
This work was financially supported by the 
Slovenian Research Agency (ARRS Grants No. P1-
0170 and L3-8203). 
References
1. Kovac V, Dodic-Fikfak M, Arneric N, Dolzan V, Franko A. Fibulin-3 as a bio-
marker of response to treatment in malignant mesothelioma. Radiol Oncol 
2015; 49: 279-85. doi: 10.1515/raon-2015-0019
2. Franko A, Kotnik N, Goricar K, Kovac V, Dodic-Fikfak M, Dolzan V. The influ-
ence of genetic variability on the risk of developing malignant mesothe-
lioma. Radiol Oncol 2018; 52: 105-11. doi: 10.2478/raon-2018-0004
3. Acencio MM, Soares B, Marchi E, Silva CS, Teixeira LR, Broaddus VC. 
Inflammatory cytokines contribute to asbestos-induced injury of mesothe-
lial cells. Lung 2015; 193: 831-7. doi: 10.1007/s00408-015-9744-4
4. Bianco A, Valente T, De Rimini ML, Sica G, Fiorelli A. Clinical diagnosis of 
malignant pleural mesothelioma. J Thorac Dis 2018; 10: S253-61. doi: 
10.21037/jtd.2017.10.09
5. Kovac V, Zwitter M, Zagar T. Improved survival after introduction of chemo-
therapy for malignant pleural mesothelioma in Slovenia: population-based 
survey of 444 patients. Radiol Oncol 2012; 46: 136-44. doi: 10.2478/v10019-
012-0032-0
6. Remon J, Lianes P, Martinez S, Velasco M, Querol R, Zanui M. Malignant 
mesothelioma: new insights into a rare disease. Cancer Treat Rev 2013; 39: 
584-91. doi: 10.1016/j.ctrv.2012.12.005
7. Plato N, Martinsen JI, Sparen P, Hillerdal G, Weiderpass E. Occupation and 
mesothelioma in Sweden: updated incidence in men and women in the 27 
years after the asbestos ban. Epidemiol Health 2016; 38: e2016039. doi: 
10.4178/epih.e2016039
8. Kadariya Y, Menges CW, Talarchek J, Cai KQ, Klein-Szanto AJ, Pietrofesa RA, 
et al. Inflammation-related IL1beta/IL1R signaling promotes the develop-
ment of asbestos-induced malignant mesothelioma. Cancer Prev Res (Phila) 
2016; 9: 406-14. doi: 10.1158/1940-6207.CAPR-15-0347
9. Melaiu O, Gemignani F, Landi S. The genetic susceptibility in the develop-
ment of malignant pleural mesothelioma. J Thoracic Dis 2018; 10: S246-52. 
doi: 10.21037/jtd.2017.10.41
10. Chapman SJ, Cookson WO, Musk AW, Lee YC. Benign asbestos pleural 
diseases. Curr Opin Pulm Med 2003; 9: 266-71. doi: 10.1097/00063198-
200307000-00004
11. Franko A, Goricar K, Kovac V, Dodic Fikfak M, Dolzan V. NLRP3 and CARD8 
polymorphisms influence risk for asbestos-related diseases. J Med Biochem 
2019; 38: 1-10. doi: 10.2478/jomb-2019-0025
12. Chew SH, Toyokuni S. Malignant mesothelioma as an oxidative stress-
induced cancer: an update. Free Radic Biol Med 2015; 86: 166-78. doi: 
10.1016/j.freeradbiomed.2015.05.002
13. Hoffman HM, Wanderer AA. Inflammasome and IL-1beta-mediated disor-
ders. Curr Allergy Asthma Rep 2010; 10: 229-35. doi: 10.1007/s11882-010-
0109-z
14. Kim YK, Shin JS, Nahm MH. NOD-Like receptors in infection, immunity, and 
diseases. Yonsei Med J 2016; 57: 5-14. doi: 10.3349/ymj.2016.57.1.5
15. Karki R, Man SM, Kanneganti TD. Inflammasomes and cancer. Cancer 
Immunol Res 2017; 5: 94-9. doi: 10.1158/2326-6066.CIR-16-0269
16. Jenko B, Praprotnik S, Tomsic M, Dolzan V. NLRP3 and CARD8 polymor-
phisms influence higher disease activity in rheumatoid arthritis. J Med 
Biochem 2016; 35: 319-23. doi: 10.1515/jomb-2016-0008
17. Bhat IA, Naykoo NA, Qasim I, Ganie FA, Yousuf Q, Bhat BA, et al. Association 
of interleukin 1 beta (IL-1beta) polymorphism with mRNA expression and 
risk of non small cell lung cancer. Meta Gene 2014; 2: 123-33. doi: 10.1016/j.
mgene.2013.12.002
Radiol Oncol 2020; 54(4): 429-436.
Piber et al. / IL1B and MIR146A SNPs in malignant mesothelioma436
18. Hai Ping P, Feng Bo T, Li L, Nan Hui Y, Hong Z. IL-1beta/NF-kb signaling 
promotes colorectal cancer cell growth through miR-181a/PTEN axis. Arch 
Biochem Biophys 2016; 604: 20-6. doi: 10.1016/j.abb.2016.06.001
19. Pillai RS. MicroRNA function: multiple mechanisms for a tiny RNA? RNA 
2005; 11: 1753-61. doi: 10.1261/rna.2248605
20. Williams AE, Perry MM, Moschos SA, Larner-Svensson HM, Lindsay MA. 
Role of miRNA-146a in the regulation of the innate immune response and 
cancer. Biochem Soc Trans 2008; 36: 1211-5. doi: 10.1042/BST0361211
21. Wang C, Zhang W, Zhang L, Chen X, Liu F, Zhang J, et al. miR-146a-5p me-
diates epithelial-mesenchymal transition of oesophageal squamous cell 
carcinoma via targeting Notch2. Br J Cancer 2018; 118: e12. doi: 10.1038/
bjc.2017.471
22. Xie YF, Shu R, Jiang SY, Liu DL, Ni J, Zhang XL. MicroRNA-146 inhibits pro-
inflammatory cytokine secretion through IL-1 receptor-associated kinase 
1 in human gingival fibroblasts. J Inflamm (Lond) 2013; 10: 20. doi: 
10.1186/1476-9255-10-20
23. Xie W, Li Z, Li M, Xu N, Zhang Y. miR-181a and inflammation: miRNA ho-
meostasis response to inflammatory stimuli in vivo. Biochem Biophys Res 
Commun 2013; 430: 647-52. doi: 10.1016/j.bbrc.2012.11.097
24. Lo Russo G, Tessari A, Capece M, Galli G, de Braud F, Garassino MC, et 
al. MicroRNAs for the diagnosis and management of malignant pleural 
mesothelioma: a literature review. Front Oncol 2018; 8: 650. doi: 10.3389/
fonc.2018.00650
25. Ghaffarzadeh M, Ghaedi H, Alipoor B, Omrani MD, Kazerouni F, Shanaki 
M, et al. Association of MiR-149 (RS2292832) variant with the risk of 
coronary artery disease. J Med Biochem 2017; 36: 251-8. doi: 10.1515/
jomb-2017-0005
26. Comer BS, Camoretti-Mercado B, Kogut PC, Halayko AJ, Solway J, Gerthoffer 
WT. MicroRNA-146a and microRNA-146b expression and anti-inflammatory 
function in human airway smooth muscle. Am J Physiol Lung Cell Mol 
Physiol 2014; 307: L727-34. doi: 10.1152/ajplung.00174.2014
27. Ichii O, Otsuka S, Sasaki N, Namiki Y, Hashimoto Y, Kon Y. Altered expression 
of microRNA miR-146a correlates with the development of chronic renal 
inflammation. Kidney Int 2012; 81: 280-92. doi: 10.1038/ki.2011.345
28. Eaton KD, Romine PE, Goodman GE, Thornquist MD, Barnett MJ, Petersdorf 
EW. Inflammatory gene polymorphisms in lung cancer susceptibility. J 
Thorac Oncol 2018; 13: 649-59. doi: 10.1016/j.jtho.2018.01.022
29. Qian H, Zhang D, Bao C. Two variants of Interleukin-1B gene are associated 
with the decreased risk, clinical features, and better overall survival of colo-
rectal cancer: a two-center case-control study. Aging (Albany NY) 2018; 10: 
4084-92. doi: 10.18632/aging.101695
30. Willems P, Claes K, Baeyens A, Vandersickel V, Werbrouck J, De Ruyck K, et 
al. Polymorphisms in nonhomologous end-joining genes associated with 
breast cancer risk and chromosomal radiosensitivity. Genes Chromosomes 
Cancer 2008; 47: 137-48. doi: 10.1002/gcc.20515
31. Tayel SI, Fouda EAM, Elshayeb EI, Eldakamawy ARA, El-Kousy SM. 
Biochemical and molecular study on interleukin-1beta gene expression and 
relation of single nucleotide polymorphism in promoter region with Type 2 
diabetes mellitus. J Cell Biochem 2018; 119: 5343-9. doi: 10.1002/jcb.26667
32. Wang J, Shi Y, Wang G, Dong S, Yang D, Zuo X. The association between 
interleukin-1 polymorphisms and their protein expression in Chinese Han 
patients with breast cancer. Mol Genet Genomic Med 2019; 7: e804. doi: 
10.1002/mgg3.804
33. Jia Y, Zang A, Shang Y, Yang H, Song Z, Wang Z, et al. MicroRNA-146a 
rs2910164 polymorphism is associated with susceptibility to non-small 
cell lung cancer in the Chinese population. Med Oncol 2014; 31: 194. doi: 
10.1007/s12032-014-0194-2
34. Svoronos AA, Engelman DM, Slack FJ. OncomiR or tumor suppressor? 
The duplicity of microRNAs in cancer. Cancer Res 2016; 76: 3666-70. doi: 
10.1158/0008-5472.CAN-16-0359
35. Wei Y, Li L, Gao J. The association between two common polymorphisms 
(miR-146a rs2910164 and miR-196a2 rs11614913) and susceptibility to 
gastric cancer: a meta-analysis. Cancer Biomark 2015; 15: 235-48. doi: 
10.3233/CBM-150470
36. Wolff H, Vehmas T, Oksa P, Rantanen J, Vainio H. Asbestos, asbestosis, and 
cancer, the Helsinki criteria for diagnosis and attribution 2014: recom-
mendations. Scand J Work Environ Health 2015; 41: 5-15. doi: 10.5271/
sjweh.3462
37. American Thoracic Society. Diagnosis and initial management of nonma-
lignant diseases related to asbestos. Am J Respir Crit Care Med 2004; 170: 
691-715. doi: 10.1164/rccm.200310-1436st
38. Dodic Fikfak M, Kriebel D, Quinn MM, Eisen EA, Wegman DH. A case 
control study of lung cancer and exposure to chrysotile and amphibole at 
a Slovenian asbestos-cement plant. Ann Occup Hyg 2007; 51: 261-8. doi: 
10.1093/annhyg/mem003
39. Dolzan V. Genetic polymorphisms and drug metabolism. Zdrav Vestn 2007; 
76 (Supll II): 5-12. 
40. Zerbino DR, Achuthan P, Akanni W, Amode MR, Barrell D, Bhai J, et al. 
Ensembl 2018. Nucleic Acids Res 2018; 46: D754-61. doi: 10.1093/nar/
gkx1098
41. Machiela MJ, Chanock SJ. LDlink: a web-based application for exploring 
population-specific haplotype structure and linking correlated alleles of 
possible functional variants. Bioinformatics 2015; 31: 3555-7. doi: 10.1093/
bioinformatics/btv402
42. Wong N, Wang X. miRDB: an online resource for microRNA target predic-
tion and functional annotations. Nucleic Acids Res 2015; 43: D146-52. doi: 
10.1093/nar/gku1104
43. Chou CH, Shrestha S, Yang CD, Chang NW, Lin YL, Liao KW, et al. miRTarBase 
update 2018: a resource for experimentally validated microRNA-target in-
teractions. Nucleic Acids Res 2018; 46: D296-302. doi: 10.1093/nar/gkx1067
44. Levpuscek K, Goricar K, Kovac V, Dolzan V, Franko A. The influence of genetic 
variability of DNA repair mechanisms on the risk of malignant mesothe-
lioma. Radiol Oncol 2019; 53: 206-12. doi: 10.2478/raon-2019-0016
45. Riva MA, Carnevale F, Sironi VA, De Vito G, Cesana G. Mesothelioma and 
asbestos, fifty years of evidence: Chris Wagner and the contribution of 
the Italian occupational medicine community. Med Lav 2010; 101: 409-15. 
PMID: 21141345
46. Muscat JE, Wynder EL. Cigarette smoking, asbestos exposure, and malig-
nant mesothelioma. Cancer Res 1991; 51: 2263-7. PMID: 2015590
47. Case BW, Abraham JL, Meeker G, Pooley FD, Pinkerton KE. Applying defini-
tions of “asbestos” to environmental and “low-dose” exposure levels and 
health effects, particularly malignant mesothelioma. J Toxicol Environ Health 
B Crit Rev 2011; 14: 3-39. doi: 10.1080/10937404.2011.556045
48. Carbone M, Ly BH, Dodson RF, Pagano I, Morris PT, Dogan UA, et al. 
Malignant mesothelioma: facts, myths, and hypotheses. J Cell Physiol 2012; 
227: 44-58. doi: 10.1002/jcp.22724
49. Hillerdal G, Henderson DW. Asbestos, asbestosis, pleural plaques and 
lung cancer. Scand J Work Environ Health 1997; 23: 93-103. doi: 10.5271/
sjweh.186
50. Maxim LD, Niebo R, Utell MJ. Are pleural plaques an appropri-
ate endpoint for risk analyses? Inhal Toxicol 2015; 27: 321-34. doi: 
10.3109/08958378.2015.1051640
51. Forloni M, Dogra SK, Dong Y, Conte D Jr, Ou J, Zhu LJ, et al. miR-146a 
promotes the initiation and progression of melanoma by activating Notch 
signaling. Elife 2014; 3: e01460. doi: 10.7554/eLife.01460
52. Jazdzewski K, Murray EL, Franssila K, Jarzab B, Schoenberg DR, de la 
Chapelle A. Common SNP in pre-miR-146a decreases mature miR expres-
sion and predisposes to papillary thyroid carcinoma. Proc Natl Acad Sci U S 
A 2008; 105: 7269-74. doi: 10.1073/pnas.0802682105
53. Shen J, Ambrosone CB, DiCioccio RA, Odunsi K, Lele SB, Zhao H. A functional 
polymorphism in the miR-146a gene and age of familial breast/ovarian can-
cer diagnosis. Carcinogenesis 2008; 29: 1963-6. doi: 10.1093/carcin/bgn172
54. Kogo R, Mimori K, Tanaka F, Komune S, Mori M. Clinical significance of 
miR-146a in gastric cancer cases. Clin Cancer Res 2011; 17: 4277-84. doi: 
10.1158/1078-0432.CCR-10-2866
55. Zhang W, Yi X, Guo S, Shi Q, Wei C, Li X, et al. A single-nucleotide polymor-
phism of miR-146a and psoriasis: an association and functional study. J Cell 
Mol Med 2014; 18: 2225-34. doi: 10.1111/jcmm.12359
56. Wang JH, Shih KS, Wu YW, Wang AW, Yang CR. Histone deacetylase inhibi-
tors increase microRNA-146a expression and enhance negative regulation 
of interleukin-1beta signaling in osteoarthritis fibroblast-like synoviocytes. 
Osteoarthritis Cartilage 2013; 21: 1987-96. doi: 10.1016/j.joca.2013.09.008
57. Chen G, Umelo IA, Lv S, Teugels E, Fostier K, Kronenberger P, et al. miR-
146a inhibits cell growth, cell migration and induces apoptosis in non-small 
cell lung cancer cells. PLoS One 2013; 8: e60317. doi: 10.1371/journal.
pone.0060317
58. Yao Q, Cao Z, Tu C, Zhao Y, Liu H, Zhang S. MicroRNA-146a acts as a metasta-
sis suppressor in gastric cancer by targeting WASF2. Cancer Lett 2013; 335: 
219-24. doi: 10.1016/j.canlet.2013.02.031
59. Wang X, Tang S, Le SY, Lu R, Rader JS, Meyers C, et al. Aberrant expression of 
oncogenic and tumor-suppressive microRNAs in cervical cancer is required 
for cancer cell growth. PLoS One 2008; 3: e2557. doi: 10.1371/journal.
pone.0002557