Case Control Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Oncol. May 15, 2020; 12(5): 535-548
Published online May 15, 2020. doi: 10.4251/wjgo.v12.i5.535
Characterization and strong risk association of TLR2 del -196 to -174 polymorphism and Helicobacter pylori and their influence on mRNA expression in gastric cancer
Caroline de Matos Lourenço, Manoela Dias Susi, Mariah Cristina Antunes do Nascimento, Vilson Serafim Junior, Ana Paula Simedan Vila, Gabriela Helena Rodrigues-Flemming, Eny Maria Goloni-Bertollo, Ana Elizabete Silva, Juliana Garcia de Oliveira-Cucolo
Caroline de Matos Lourenço, Manoela Dias Susi, Department of Graduate-Level Research, Sacred Heart University, Bauru, São Paulo 17011-970, Brazil
Mariah Cristina Antunes do Nascimento, Vilson Serafim Junior, Ana Paula Simedan Vila, Gabriela Helena Rodrigues-Flemming, Eny Maria Goloni-Bertollo, Juliana Garcia de Oliveira-Cucolo, Department of Molecular Biology, São José do Rio Preto School of Medicine, São José do Rio Preto, São Paulo 15090-000, Brazil
Ana Elizabete Silva, Department of Biology, São Paulo State University, São José do Rio Preto, São Paulo 15054-000, Brazil
Author contributions: Oliveira-Cucolo JG and Silva AE conceived and designed the experiments; Lourenço CM, Susi MD, Serafim Junior V and Vila APS performed the experiments; Nascimento MCA provided technical support; Oliveira-Cucolo JG, Serafim Junior V and Rodrigues-Flemming GH analyzed and interpreted the data; Silva AE and Goloni-Bertollo EM contributed to the collection of samples/reagents/materials and analysis tools; Oliveira-Cucolo JG, Rodrigues-Flemming, Goloni-Bertollo EM and Silva AE drafted and revised the manuscript; All of the authors approved the final version of the manuscript for publication.
Supported by the São Paulo Research Foundation, No. 2013/14022-6 and No. 2014/17716-1.
Institutional review board statement: This study was approved by the local Research Ethics Committee (registration number: 382.514).
Conflict-of-interest statement: The authors declare no conflicts of interest.
Informed consent statement: The participants provided written informed consent for data sharing.
STROBE statement: The authors have read the STROBE Statement-checklist of items, and the manuscript was prepared and revised according to the STROBE Statement-checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Ana Elizabete Silva, PhD, Adjunct Professor, Department of Biology, São Paulo State University, Rua Cristóvão Colombo, 2265, São José do Rio Preto, São Paulo 15054-000, Brazil.
Received: December 13, 2019
Peer-review started: December 13, 2019
First decision: January 14, 2020
Revised: January 30, 2020
Accepted: April 4, 2020
Article in press: April 4, 2020
Published online: May 15, 2020

Toll-like receptor-2 (TLR2) is responsible for recognizing Helicobacter pylori (H. pylori) and activating the immune response. Polymorphisms in TLR2 may modulate gastric carcinogenesis.


To evaluate whether the TLR2 19216T/C (rs3804099) and TLR2 -196 to -174 ins/del (rs111200466) polymorphisms contribute to gastric carcinogenesis in the Brazilian population, and to determine the influence of both polymorphisms and H. pylori infection on TLR2 mRNA expression.


DNA was extracted from 854 peripheral blood leukocyte or gastric tissue samples [202 gastric cancer (GC), 269 chronic gastritis (CG), and 383 control/healthy (C)] and genotyped by allele-specific PCR or restriction fragment length polymorphism (RFLP)-PCR. Quantitative polymerase chain reaction by TaqMan® assay was used to quantify TLR2 mRNA levels in fresh gastric tissues (48 GC, 36 CG, and 14 C).


Regarding the TLR2 -196 to -174 polymorphism, the ins/del and del/del genotypes were associated with a higher risk of GC by comparison with the C in all of the analyzed inheritance models (codominant, dominant, recessive, overdominant and log-additive; P < 0.0001). Similarly, an increased risk was observed when comparing the GC and CG groups [codominant (P < 0.0001), dominant (P < 0.0001), recessive (P = 0.0260), overdominant (P < 0.0001) and log-additive (P < 0.0001)]. In contrast, TLR2 19216T/C was associated with a protective effect in the GC group compared to the C group [dominant (P = 0.0420) and log-additive (P = 0.0300)]. Regarding the association of polymorphisms with H. pylori infection, individuals infected with H. pylori and harboring the TLR2 -196 to -174 ins/del polymorphism had an increased risk of gastric carcinogenesis [codominant (P = 0.0120), dominant (P = 0.0051), overdominant (P = 0.0240) and log-additive (P = 0.0030)], while TLR2 19216T/C was associated with a protective effect [codominant (P = 0.0039), dominant (P < 0.0001), overdominant (P = 0.0097) and log-additive (P = 0.0021)]. TLR2 mRNA levels were significantly increased in the GC group (median RQ = 6.95) compared to the CG group (RQ = 0.84, P < 0.0001) and to the normal mucosa group (RQ = 1.0). In addition, both H. pylori infection (P < 0.0001) and the presence of the polymorphic TLR2 -196 to -174del (P = 0.0010) and TLR2 19216 C (P = 0.0004) alleles influenced TLR2 mRNA expression.


The TLR2 -196 to -174 ins/del and TLR2 19216 T/C polymorphisms are strongly associated with GC. TLR2 mRNA expression levels are upregulated in neoplastic tissues and influenced by both the presence of H. pylori and variant genotypes.

Keywords: Toll-like receptor 2, Helicobacter pylori, Gastric cancer, Chronic gastritis, Polymorphisms, Gene expression

Core tip: This study showed that two polymorphisms in toll-like receptor-2 (TLR2) are strongly associated with gastric cancer and Helicobacter pylori (H. pylori) infection in the Brazilian population. TLR2 mRNA expression was increased in gastric cancer tissue compared with chronic gastritis and normal tissues. Moreover, TLR2 mRNA expression levels were upregulated in gastric cancer in the presence of the TLR2 -196 to -174 del variant allele or the wild-type TLR2 19216 T allele and in the presence of H. pylori. Thus, gene polymorphisms that change expression levels, such as those in TLR2, may alter the immune response and, consequently, the development and clinical manifestations of cancer.