RESUMO
PURPOSE: Accumulating reports have shown the oncogenic properties of PPMD1 (protein phosphatase, Mg2+/Mn2+ dependent 1D) in different cancer types. This study was undertaken to explore the role and therapeutic potential of PPM1D in colon cancer. METHODS: HT-29 colon cancer cell line was used in this study. Expression analysis of PPMD1 was performed by qRT-PCR. Cell viability was determined by CCK-8 assay. DAPI, acridin orange/ethidium bromide (AO/EB) and propidium iodide (PI)staining assays were used for apoptosis detection. Cell cycle analysis was performed by flow cytometry. Protein expression was determined by western blot analysis. RESULTS: The results showed that the expression of PPMD1 was significantly upregulated in colon cancer by 3.2 to 4.8 fold. Silencing of PPMD1 caused significant decline in the proliferation rate of the HT-29 colon cancer cells that was due to induction of apoptosis as evidenced by DAPI, AO/EB and PI staining. Annexin V/PI showed a significant increase in the percentage of apoptotic of HT-29 cells upon silencing of PPMD1. The induction of apoptosis was also accompanied by increase in Bax and decrease in Bcl-2 expression. PPMD1 silencing also resulted in arrest of the HT-29 cells in the G2/M phase of the cell cycle which was also associated with upsurge of p21 and p53 and depletion of cyclin B1 expression levels. PPMD1 silencing also caused decrease in the viability of the HT-29 cells which was concomitant with suppression of MMP-2 and MMP-9 expression. CONCLUSION: These findings suggest that PPMD1 has oncogenic properties in colon cancer and exhibit therapeutic implications in colon cancer treatment.
