Transcription factor AP-1 in esophageal squamous cell carcinoma: Alterations in activity and expression during Human Papillomavirus infection

<p>Abstract</p> <p>Background</p> <p>Esophageal squamous cell carcinoma (ESCC) is a leading cause of cancer-related deaths in Jammu and Kashmir (J&K) region of India. A substantial proportion of esophageal carcinoma is associated with infection of high-risk HPV type 16 and HPV18, the oncogenic expression of which is controlled by host cell transcription factor Activator Protein-1 (AP-1). We, therefore, have investigated the role of DNA binding and expression pattern of AP-1 in esophageal cancer with or without HPV infection.</p> <p>Methods</p> <p>Seventy five histopathologically-confirmed esophageal cancer and an equal number of corresponding adjacent normal tissue biopsies from Kashmir were analyzed for HPV infection, DNA binding activity and expression of AP-1 family of proteins by PCR, gel shift assay and immunoblotting respectively.</p> <p>Results</p> <p>A high DNA binding activity and elevated expression of AP-1 proteins were observed in esophageal cancer, which differed between HPV positive (19%) and HPV negative (81%) carcinomas. While JunB, c-Fos and Fra-1 were the major contributors to AP-1 binding activity in HPV negative cases, Fra-1 was completely absent in HPV16 positive cancers. Comparison of AP-1 family proteins demonstrated high expression of JunD and c-Fos in HPV positive tumors, but interestingly, Fra-1 expression was extremely low or nil in these tumor tissues.</p> <p>Conclusion</p> <p>Differential AP-1 binding activity and expression of its specific proteins between HPV - positive and HPV - negative cases indicate that AP-1 may play an important role during HPV-induced esophageal carcinogenesis.</p

Methylation-mediated gene silencing of suppressor of cytokine signaling-1 (SOCS-1) gene in esophageal squamous cell carcinoma patients of Kashmir valley

Context: Esophageal squamous cell carcinoma (ESCC) is a leading cause of cancer-related deaths in Jammu and Kashmir. The negative regulation of tumor suppressor gene leading to change in signaling pathway is one of the major mechanisms responsible for tumorigenic transformation. Objective: In the present study, the role of silencing of suppressor of cytokine signaling-1 (SOCS-1) gene, a negative regulator of JAK/STAT pathway, was analyzed in ESCC. Methods: The expression pattern of SOCS-1 gene was analyzed in esophageal tumor biopsies although normal adjacent tissues that served as controls. Reverse transcriptase polymerase chain reaction (RT-PCR), immunohistochemistry, methylation-specific PCR (MSP), and human papillomavirus (HPV) detection were performed to assess the expression pattern and promoter methylation of SOCS-1 gene including HPV status in a total of 75 surgically resected tissue specimens. Results: Compared with the level of SOCS-1 expression in normal tissues, 53% (40/75) of the tumor tissues expressed either undetectable or reduced SOCS-1 expression (&gt;50% loss of expression), which was significantly associated with advanced clinical stage or severe histopathological grade of the disease (P&lt;0.01). Aberrant promoter methylation of the SOCS-1 gene was found in 45% (34/75) of the esophageal tumor tissues, which was also found to be significantly associated with advanced stage of esophageal carcinoma (P&lt;0.01). The prevalence of HPV infection was found in 19% of tumor cases, whereas no HPV could be detected in any of the normal adjacent tissues. Conclusion: Transcriptional inactivation of SOCS-1 gene, primarily due to its promoter hypermethylation although HPV infection, may play an important role in esophageal carcinogenesis in Kashmir

Association of cyclin D1 gene polymorphisms with risk of esophageal squamous cell carcinoma in Kashmir valley—a high risk area

Investigation of potential association of SNPs (G870A, rs9344; G1722C, rs678653) of cyclin D1 gene (CCND1) with susceptibility to esophageal squamous cell carcinoma (ESCC) in Kashmir valley (India). The study included 302 subjects comprising 151 ESCC cases and 151 controls. PCR-RFLP and direct sequencing were employed for genotyping. The G870A polymorphism, the individuals carrying GA+AA genotype was having 2.80-fold increased risk for development of ESCC (OR 2.8, 95% CI=1.77-4.4; P=0.0001) compared to GG genotype. Further a significantly higher risk was observed in individuals who consume >3 cups per day of salted tea (OR=5.1; 95% CI=1.6-16.7; P=0.0016) and had smoking habits (OR=6.3; 95% CI=2.9-13.9; P=0.0005). We also demonstrate for the first time in CCND1 1722 locus, the CC genotype was strongly associated with increased risk of developing ESCC (OR=2.58; 95% CI=1.61-4.15; P=0.0001). In addition, the frequency of polymorphic C allele was also found to be higher in cases (OR=1.92; 95% CI=1.37-2.69; P=0.0002). There appears to be an influence of CCND1 G870A/G1772C genotypes on genetic susceptibility to ESCC. Mol. Carcinog

Aberrant promoter methylation and reduced expression of p16 gene in esophageal squamous cell carcinoma from Kashmir valley: a high-risk area

Esophageal squamous cell carcinoma (ESCC) is one of the most prevalent cancer in Jammu and Kashmir region of India and has multi-factorial etiology involving dietary habits, genetic factors, and gene environmental interactions. Inactivation of the p16 gene expression by aberrant promoter methylation plays an important role in the progression of esophageal carcinoma. In the present investigation, we have studied the role of p16 promoter methylation in 69 histopathologically confirmed ESCC tissues and compared it with corresponding normal adjacent tissues for DNA methylation in the CpG island in the p16 promoter region by methylation-specific polymerase chain reaction (MSP) and p16 protein expression by immunoblotting. The results showed loss of p16 expression in 67% (46/69) of tumor tissues compared to only 3% in control tissues (2/69). Promoter methylation was observed in 52% (36/69) of tumor tissues and it gradually increased with the increasing severity of histological grades of the cancer (P = 0.0001). Loss of p16 expression with promoter methylation was observed in 26 of 36 cases (72%). Analysis of patients dietary habits revealed a strong association between promoter methylation and high consumption of hot salted tea (P &#60; 0.05) which is a most favourite drink commonly consumed by Kashmiri people