Epigenetic modification-mediated inhibition of SOSTDC1 expression promotes malignant biological behaviors in cervical cancer cells.

Objective: To investigate the role of sclerostin domain-containing protein 1 (SOSTDC1) in regulating malignant biological behaviors of cervical cancer (CC) cells and its molecular mechanism through in vitro experiments. Methods: Fifty-three cervical cancer tissues and corresponding paracancerous tissues were collected from biopsy or surgical resection at Fujian Cancer Hospital between August 2020 and May 2022, immunohistochemistry was used to investigate SOSTDC1 expression in CC and adjacent cervical tissue specimens. qPCR was performed to detect SOSTDC1 mRNA expression levels in normal cervical tissues and CC cells. CC cells SiHa and CaSki transfected with SOSTDC1 over-expression lentiviruses (OE-sostdc1) and negative control (NC) viruses were divided into SiHa-OE-sostdc1 group, SiHa-NC group, CaSki-OE-sostdc1 group and CaSki-NC group. WST-1, colony formation, and Transwell assays were used to detect the proliferative, colony-formative, migratory and invasive abilities of SiHa and CaSki cells in all the groups. The expressions of proteins related to BMP, Wnt/β -catenin signaling pathways, and epithelial mesenchymal transition (EMT) were detected by Western blotting. qPCR and WB arrays were performed on CC cells treated with the DNA methylation inhibitor 5-aza-2'-deoxycytidine (5'-Aza-CdR) to detect the changes in the expressions of SOSTDC1 mRNA and proteins. Methylation-specific PCR (MSP) assay was performed to analyze the level of gene promoter methylation of SOSTDC1 in 5 pairs of CC and para-cancerous tissue samples, while qPCR was used to detect SOSTDC1 mRNA levels in the tissues. Results: The expression of SOSTDC1 protein was significantly reduced in CC tissues compared with para-cancerous tissues (P<0.01), and low SOSTDC1 expression was found to be correlated with lymph node metastasis and FIGO staging (all P<0.05). The expression levels of SOSTDC1 mRNA were significantly reduced in C33A, HeLa, SiHa and CaSki cells compared with normal cervical HUCEC cells. Over-expression of SOSTDC1 significantly inhibited the proliferative, migratory, and invasive abilities of SiHa and CaSki cells (all P<0.05). WB analysis showed that over-expression of SOSTDC1 significantly inhibited the expressions of p-Smad, Dvl2/3, β -catenin, vimentin, N-cadherin and Snail proteins in SiHa and CaSki cells (all P<0.05). The levels of SOSTDC1 mRNA and protein in SiHa and CaSki cells treated with 5'-Aza- CdR treatment were significantly increased (all P<0.05). MSP analysis showed that compared with in para-cancerous tissues, the SOSTDC1 gene promoter was highly methylated in CC tissues, while the expression of SOSTDC1 mRNA was down-regulated (P<0.01). Conclusion: SOSTDC1 is downregulated in cervical cancer tissues, and low SOSTDC1 expression is correlated with malignant progression of tumors. SOSTDC1 may suppress the proliferative, migratory, and invasive abilities of SiHa and CaSki cells through blocking BMP and Wnt/β-catenin signaling pathways. [ABSTRACT FROM AUTHOR]