Protein inhibitor of activated signal transducer and activator of transcription 2 is an oncoprotein in oral squamous cell carcinoma and related to cigarette smoking - An in vitro study

Background/purpose

Oral cancer is one of the most prevalent malignant tumors in Taiwan. Due to the heterogeneity of oral cancer cells, the five-year survival rate of patients is only 50%. Post-translational modifications contribute to protein diversity and directly influence cell functions. The protein inhibitor of activated signal transducer and activator of transcription 2 (PIAS2) is known to undergo post-translational modifications, yet its impact on oral cancer remains unclear.

Materials and methods

PIAS2 expression was modulated by transfecting cells with a PIAS2 expression vector or by knocking down PIAS2 using siRNA with low and high PIAS2 expression, respectively. These cells were subjected to invasion, migration, and proliferation assays to evaluate the effects of PIAS2. Changes in genotype, such as epithelial-mesenchymal transition (EMT) markers, were also examined. Additionally, the effect of cigarette smoke condensate (CSC) on PIAS2 expression in oral squamous cell carcinoma (OSCC) cells was investigated.

Results

Overexpression of PIAS2 significantly increased the malignant behaviors of oral cancer cells. In YD38 and SAS cells with low PIAS2 expression, overexpression of PIAS2 enhanced proliferation, invasion, and migration. PIAS2 overexpression also affected EMT gene expression, suppressing E-cadherin and increasing fibronectin expression. Conversely, PIAS2 knockdown in OECM1 and SCC25 cells suppressed malignant behaviors and reversed EMT markers, increasing E-cadherin and decreasing fibronectin expression. Furthermore, a dose-dependent increase in PIAS2 expression was observed when OSCC cells were treated with CSC.

Conclusion

PIAS2 functions as an oncogene in oral cancer, and cigarette smoking induces PIAS2 expression. Increased PIAS2 levels lead to enhanced malignancy in oral cancer.