Overexpressed GATA3 enhances the sensitivity of colorectal cancer cells to oxaliplatin through regulating MiR-29b.

BACKGROUND: GATA binding protein 3 (GATA3) and miR-29b are related to colorectal cancer (CRC). The current study explored the regulatory relationship between GATA3 and miR-29b, and the mechanism of the two in the drug resistance of CRC cells to oxaliplatin. METHOD: Apoptosis of CRC cells induced by oxaliplatin at various doses was detected by flow cytometry. CRC cells were separately transfected with overexpression and knockdown of GATA3, miR-29b agomir and antagomir, and treated by oxaliplatin to detect the cell viability and apoptosis by performing Cell Couting Kit-8 (CCK-8) and flow cytometry. The expression levels of GATA3, caspase3 and cleaved caspase3 were determined by Western blot, and the expression of miR-29b was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Animal experiments were performed to examine the changes of transplanted tumors in nude mouse xenograft studies and observed by in vivo imaging. TUNEL staining was performed to detect tumor cell apoptosis. RESULT: Both GATA3 and miR-29b agomir inhibited the activity of the CRC cells, promoted apoptosis and Cleaved caspase3 expression, and reduced the resistance of the cells to chemotherapy drug oxaliplatin. Although GATA3 could up-regulate miR-29b expression, the tumor-suppressive effect of GATA3 was partially reversed by miR-29b antagomir. In vivo experiments showed that down-regulating the expression of GATA3 promoted the growth rate and volume of transplanted tumors, while overexpressing GATA3 had no significant effect on tumor growth. TUNEL staining results showed that knocking down or overexpression of GATA3 did not cause significant changes to apoptotic bodies of CRC cells, while oxaliplatin treatment increased the number of apoptotic bodies. CONCLUSION: GATA3 inhibits the cell viability of CRC cells, promotes apoptosis, and reduces oxaliplatin resistance of CRC cells through regulating miR-29b.