Aberrant Hypermethylation of SALL3 with HPV Involvement Contributes to the Carcinogenesis of Cervical Cancer.

Abstract

OBJECTIVE:

This study aimed to investigate the methylation status of the promoter region of spalt-like transcription factor 3 (SALL3) and the expression of SALL3 in cervical cancer to explore the function of this gene in cervical cancer carcinogenesis.

METHODS:

The methylation status of SALL3 was detected by methylation-specific PCR, and SALL3 gene expression was assessed by real-time quantitative PCR in the cervical cancer cell lines, SiHa, HeLa and C33A, as well as in cervical cancer tissue samples (n = 23), matched pericarcinomatous tissue samples (n = 23) and normal cervix tissue samples (n = 17). MTT was used to measure the cell viability and proliferation capacity of SiHa and HeLa cells.

RESULTS:

The SALL3 promoter was completely methylated in SiHa cells, unmethylated in C33A cells and partially methylated in HeLa cells. After treatment of SiHa and HeLa cells with 5 μM and 10 μM of 5-Azacytidine (5-Aza), respectively, the methylation level of the SALL3 promoter decreased and observed increase in the degree of unmethylation in a dose-dependent manner. Moreover, the relative expression of SALL3 mRNA increased as the concentration of 5-Aza increased in SiHa (p<0.05) and HeLa (p<0.05) cells. This above-mentioned increase in SALL3 mRNA in SiHa cells was more remarkable than that observed in HeLa cells. Cell proliferation capacity also decreased after administration of 5-Aza to SiHa and HeLa cells (p<0.05). Methylation of the SALL3 promoter was observed in 15 of 23 (65.21%) cervical cancer tissue samples, 15 of 23 (65.21%) matched pericarcinomatous tissue samples and 5 of 17 (29.41%) normal cervical tissue samples (p<0.05). SALL3 mRNA expression was significantly lower in cervical cancer and pericarcinomatous tissues compared with normal cervical tissues (p<0.05). In all cervix tissue samples, HPV infection was positively associated with hypermethylation of the promoter region of SALL3 (p<0.05, r = 0.408), and the expression of SALL3 mRNA in HPV-positive tissues was lower than that in HPV-negative tissues (p<0.05).

CONCLUSION:

The aberrant hypermethylation of SALL3 together with HPV involvement inactivated its function as a tumor suppressor and contributed to carcinogenesis in cervical cancer.

• Authors: Xing Wei, Shaohua Zhang, Di Cao, Minyi Zhao, Qian Zhang, Juan Zhao, Ting Yang, Meili Pei, Li Wang, Yang Li, Xiaofeng Yang
• Journal: PloS one (PLoS One) Vol. 10 Issue 12 Pg. e0145700 ( 2015) ISSN: 1932-6203 [Electronic] United States
• PMID: 26697877 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Homeodomain Proteins
• RNA, Messenger
• SALL3 protein, human
• Transcription Factors

Topics

• Blotting, Western
• Carcinogenesis (genetics, pathology)
• Case-Control Studies
• Cell Proliferation
• Cervix Uteri (metabolism)
• DNA Methylation
• Female
• Gene Expression Regulation, Neoplastic
• Homeodomain Proteins (genetics)
• Humans
• Papillomaviridae (pathogenicity)
• Papillomavirus Infections (complications, virology)
• Promoter Regions, Genetic
• RNA, Messenger (genetics)
• Real-Time Polymerase Chain Reaction
• Reverse Transcriptase Polymerase Chain Reaction
• Transcription Factors (genetics)
• Tumor Cells, Cultured
• Uterine Cervical Neoplasms (etiology, pathology)