The Association Between The Bcl-2,Survivin Polymorphisms And Papillary Thyroid Carcinoma Risk And The Correlation Of These Polymorphisms With The Bcl-2,Survivin Expression

Part1. The association between the bcl-2-938C/A, survivin9194A/G polymorphisms and papillary thyroid carcinoma risk in Han Chinese populationBackground and Objective:Thyroid cancer, the most common type of endocrine malignancy, accounts for the majority of endocrine cancer related to death each year. Papillary thyroid carcinoma (PTC) comprises the vast majority (65%-75%) of all thyroid cancers. The yearly incidence of PTC has a2.9-fold increase from1988to2002, and this trend appears to be continuing. The etiologic risk factors for PTC remain largely unknown. Accumulating evidence suggests that genetic polymorphisms influence the risk of environmental carcinogenesis, and that genetic susceptibility plays an important role in the development of human cancers. Dysregulation of apoptosis plays a key role in carcinogenesis also. Several studies have recently reported the possible association between several single-nucleotide polymorphisms (SNPs) of apoptosis-related gene (e.g. Bcl-2and Survivin) and a few types of human cancers. However,association of Bcl-2and Survivin gene polymorphisms and PTC susceptibility has not been reported. Thus, in this study, in order to clarify association between Bcl-2(-938C/A), Surviving194A/G) SNPs and PTC risk, we have performed a hospital-based case-control study on Han Chinese population.Methods:We undertook a case-control study of126patients and198controls to investigate the association between Bcl-2(-938C/A), Survivin (9194A/G) polymorphisms and PTC susceptibility. Genomic DNA from whole blood cells was extracted, following polymerase chain reaction (PCR) and DNA sequencing methods. All samples were collected before any kind of therapeutic measures between March2008and October2010at the Department of Endocrinology and Department of Surgery, The Affiliated Hospital of Binzhou Medical University. All patients were submitted to thyroidectomy.We further analyzed the distribution of genotype frequency, as well as the association of genotype with clinicopathological characteristics. Frequency and susceptibilities of mutations were compared with the χ2test. The crude and adjusted odds ratio (ORs) and the corresponding95%confidence intervals (CI) were calculated using unconditional multiple logistic regression.Results:1. The genotypic distributions of Bcl-2(-938C/A), Survivin (9194A/G) gene polymorphisms in cases and controls groups were in HWE (all,P>0.05).2. Bcl-2-938AA genotype demonstrated a protective effect in PTCs (P=0.040; adjusted OR=0.35). In case of alleles, association was only observed with A allele of Bcl-2(-938C>A)with statistically significant reduced risk of PTC (P=0.029, OR=0.64). Furthermore, the AA genotype thyroid cancers were significantly more common in cases of lower pathological stages than CC and CA genotypes PTCs. The AA genotype thyroid cancers were significantly more common in cancers of lower pathological stages (stages1&2versus3&4, P=0.03).3. For the Survivin9194A/G polymorphism, the variant allele frequency AG and GG of9194A/G was higher in controls as compared with cases (P=0.021, P=0.039, adjusted OR=0.77, adjusted OR=0.59, respectively), the9194GG genotype was associated with a significantly decreased risk of PTC compared to the combined9194AA+AG genotype (P=0.003; OR=0.56). Furthermore, the GG genotype thyroid cancers were significantly more common in younger patients and in cases of lower pathological stages than AA and AG genotypes PTCs. The polymorphism was not related to the gender of the patients and pathologic features (histologic variant, multicentricity, capsule invasion, and lymph node metastasis) of the cancer. Although the polymorphism was not related to the presence of lymph nodal metastases, the GG genotype was significantly related to age, tumor size, T stage and lower pathologic stages (P=0.028, P=0.045,P=0.042and P=0.038, respectively).Conclusions:1. Bcl-2-938C/A and Survivin9194A/G polymorphisms were associated with papillary thyroid carcinoma risk in Han Chinese population.2. The Bcl-2-938AA genotype and A allele,Survivin9194GG genotype and G allele were indicated to play a protective role in the susceptibility to PTC. Part2. The association between the expression of bcl-2,survivin in papillary thyroid carcinoma tissues and the bcl-2,survivin gene polymorphismsBackground and Objective:Previous studies have reported that the expression of anti-apoptotic protein including bcl-2,survivin was abnormal in some kinds of tumor tissues, and the expression level of these proteins are related to tumor characteristics and clinical outcome. Accumulating evidence suggests that genetic polymorphisms influence the risk of environmental carcinogenesis, and that genetic susceptibility plays an important role in the development of human cancers. The polymorphisms may be associated with many disease by affecting gene transcription and protein expression. Present study has shown that bcl-2-938C/A and survivin9194A/G polymorphisms were associated with papillary thyroid carcinoma. Next, we further investigate the association between the expression of bcl-2and survivin protein in papillary thyroid carcinoma tissues and the bcl-2,survivin gene polymorphisms.Methods:1. Paraffin-embedded samples were obtained from126patients that were diagnosed with PTC at the Department of Endocrinology and the Department of Surgery, Affiliated Hospital of Binzhou Medical Universitybetween March2008and October2010.2. Immunohistochemistry was performed to examine the expression of bcl-2,survivin protein in PTC tissues and adjacent non-malignant thyroid tissues.3. The correlation between bcl-2, survivin expression and bcl-2-938C/A, survivin9194A/G genotype was assessed by χ2test.Results:1. Immunohistochemistry analysis demonstrated that the expression of bcl-2is higher (58.4%) in PTC tissue, however bcl-2expression in the adjacent non-malignant tissue was absent or lower expression.2. Bcl-2protein was high expression in cases of tumor size≥20mm, T3+4stages, lymph node metastasis positive and TNM III+IV stages, P<0.001, P<0.001, P=0.016and P<0.001, respectively.3. Immunohistochemistry analysis demonstrated that the expression of survivin is higher (45.1%) in PTC tissue, compared with that in the adjacent non-malignant tissue. The difference of survivin expression between PTC tissue and the adjacent non-malignant is significant(P<0.001).4. The expression of survivin was not related to age, the gender of the patients and pathologic features (tumor size, multicentricity, T stage and TNM pathological stage) of the cancer. The cases of capsule invasion (78.0%) and lymph node metastasis (60.0%) have a higher expression of survivin,P<0.001, P=0.011, respectively.5. Bcl-2expression in AA, CC and AC genotype of PTC were31.8%,72.7%and57.7%.%test analysis revealed that with expression of bcl-2in AA genotype PTC was much lower than that of CC genotype PTC(P=0.001). Survivin expression in AA, AG and GG genotype of PTC were42.5%,53.1%and40%. χ2test analysis revealed that with expression of survivin in AA genotype PTC was not different with that of AG and GG genotype PTC(P>0.05).Conclusions:1. High expression of bcl-2was related with poor pathologic features of papillary thyroid carcinoma. High expression of survivin was related with invasion and lymph node metastasis of papillary thyroid carcinoma.2. The polymorphism of bcl-2-938C/A affected expression of bcl-2protein of PTC, and cases of AA genotypes have a lower expression of bcl-2. The polymorphism of survivin9194A/G did not affect the survivin expression in PTC tissues.