Screening of candidate tumor-suppressor genes in 3p21.3 and investigation of the methylation of gene promoters in oral squamous cell carcinoma

Abstract

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck malignant tumor. however, its pathological mechanisms have not yet been elucidated. In the present study, we screened for candidate tumor-suppressor genes (TSGs) related to OSCC among 10 candidate genes located in 3p21.3, a region abundant with TSGs based on previous studies, using semi-quantitative reverse transcription PCR (RT-PCR). Three genes, GNAT1, SEMA3B and AXUD1, with low or no expression in OSCC tissues and the cell line TCA8113 were selected, and the promoter methylation status was further analyzed by methylation-specific PCR (MS-PCR). Hypermethylation in the promoter regions of SEMA3B was found in OSCC tissues, and a significant difference in the frequency of methylation of SEMA3B was observed between OSCC and non-cancerous tissues. Furthermore, TCA8113 cells treated with 5-Aza-Cdc started to re-express SEMA3B at a concentration of 5 µM or higher. Our study confirmed that three candidate TSGs with low expression may be involved in OSCC and that hypermethylation in promoter regions may contribute to the low expression of SEMA3B. These findings offer novel insights for clarifying the molecular mechanisms of tumorigenesis of OSCC as well as for aiding in its clinical diagnosis and therapeutic strategy.

The role of the semaphorins in cancer

“…91,[145][146][147][148][149][150] Sema3B also functions as an endogenous inhibitor of endometrial cancer, 151 and in oral squamous cell carcinoma in which its expression is inhibited as a result of promoter methylation. 152 In agreement with these observations single nucleotide polymorphisms in the sema3B gene were also found to be associated with poor prognosis of prostate cancer. 153 Furthermore, a single nucleotide alteration in the sema3B gene (T415I) resulted in decreased sema3B function and was associated with increased susceptibility to lung cancer in African-Americans and Latino-Americans indicating that sema3B plays a role in the determination of predisposition to lung cancer.…”

Re‐expression ofLactotransferrin, a candidate tumor suppressor inactivated by promoter hypermethylation, impairs the malignance of oral squamous cell carcinoma cells.

“…As for LTF , it had been clear that hypermethylation was an important mechanism of LTF silence in prostate cancer, lung cancer, as well as nasopharyngeal carcinoma . And, we also reported the hypermethylation status of SEMA3B in our previous work . Here, low or absent expression of LTF was also observed in OSCC tissues and TCA8113 cells by IHC, RT‐PCR, and qPCR, another case reflecting the universal expression pattern of LTF in tumors.…”

“…Previously, we have identified three candidate tumor suppressor genes (TSGs) in 3p21.3, one of preferred regions abundant with TSGs, by semiquantitative reverse‐transcription PCR. And we also demonstrated that the hypermethylation in promoter regions were associated with the low expression of the candidate TSGs in OSCC . So, we wonder that LTF , also locating at 3p21.3 , which have been identified as a TSGs in other cancers, would exert similar functions in OSCC.…”

Impact of Storage Temperature on the Expression of Cell Survival Genes in Cultured ARPE-19 Cells

“…36 Its function is essential for normal development of the brain, 37 and it is a known negative regulator of the Wnt pathway. 38 The expression of TRIB1 increased 7.5-fold in cells stored at 16°C compared to control cultures. The characterization of TRIB-1 as either a tumor suppressor 27 or an oncogene 30 is a matter of ongoing debate.…”

“…63,64 Interestingly, CSRNP1, the second most upregulated gene after 16°C storage, is a known negative regulator of the Wnt pathway. 38 Several genes of the JAK/STAT-pathway showed expression changes after storage at all temperatures, though most increased in the 16°C group because of the prominent activation of c-FOS. The JAK/STAT pathway serves as the main signaling mechanism for many cytokines and growth factors.…”