The inhibition of MARK2 suppresses cisplatin resistance of osteosarcoma stem cells by regulating DNA damage and repair.

OBJECTIVE

This study aims to explore the role of MARK2 in chemotherapeutic resistance and potential mechanism within cisplatin resistance models of CD133 MG-63 and MNNG/HOS cells.

METHODS

CD133 and CD133 MG-63 and MNNG/HOS cells were differentiated and obtained by MACS(Magnetic bead sorting). Cell activity was determined by CCK-8 assay. siRNA was employed to down regulate the Microtubule Affinity Regulated Kinase 2 (MARK2) expression. Immunofluorescence detection and RT-qPCR were used to measure the expressions of MARK2 and DNA-PKcs at both protein and mRNA levels. Western blot was applied to test the levels of MARK2, γH2AX (S139), DNA-PKcs, Phospho-PI3 Kinase p85 (Tyr458), Akt, phospho-Akt (T308) antibodies, mTOR, phospho-mTOR (Ser2448).

RESULTS

Compared with CD133 MG-63 cells, CD133 MG-63 cells showed significantly strong cisplatin resistance, with high levels of MARK2, DNA-PKcs and potent DNA damage repair ability (<0.05). Down regulation of MARK2 reduced the cisplatin resistance of CD133 MG-63 cells, with deceasing expression of DNA-PKcs (<0.05). PI3K/Akt/mTOR pathway was potentially activated in CD133 MG-63 cells, and involved in the cisplatin resistance of MG-63 cells. The similar results were observed in CD133 MNNG/HOS cells. The reduction of MARK2 retarded the activity of PI3K/Akt/mTOR pathway and further impeded the cisplatin resistance in CD133 MG-63 and MNNG/HOS cell.

CONCLUSION

Our data suggested that MARK2 was related to cisplatin resistance in CD133 MG-63 and MNNG/HOS cells. The decrease of MARK2 restricted the cisplatin resistance of CD133 MG-63 and MNNG/HOS cells by down regulating the expression of DNA dependent protein kinase catalytic subunit (DNA-PKcs) and inhibiting activity of PI3K/Akt/mTOR signaling pathway, which provides new clues for the osteosarcoma chemotherapy strategy.