1. Department of Pathology, Tianjin Union Medical Center, Nankai University, Tianjin, 300121, P.R. China.
2. Nankai University School of Medicine, Nankai University, Tianjin, 300071, P.R. China.
3. Department of Colorectal Surgery, Tianjin Union Medical Center, Tianjin, 300121, P.R. China.
4. State Key Laboratory of Medicinal Chemical Biology, NanKai University, Tianjin, 300071, P.R. China.
#These authors equally contributed the paper.
Purpose: Our previous studies have shown that CoCl2 can induce the formation of polyploid giant cancer cells (PGCCs) and PGCCs could produce progeny cells via asymmetric division. In this study, the molecular mechanism by which PGCCs generate progeny cells with high invasion and migration abilities was explored.
Methods: In this study, PGCCs induced by CoCl2 produced progeny cells via asymmetric division, which was observed dynamically using laser scanning confocal microscopy. Cell cycle in LoVo and Hct116 before and after CoCl2 treatment was analyzed by flow cytometry. Cell function experiments, co-immunoprecipitation, mass spectrometry analysis, ML141 treatment, western blotting, and siRNA transfection experiments were used to demonstrate that Cdc42/PAK1 was involved in the regulation of cytoskeleton expression. The proliferation, migration, and invasion abilities of PGCCs and progeny cells were compared in PGCCs and progeny cells with and without inhibiting the expression of Cdc42 and PAK1.
Results: G2/M phase arrest appeared in CoCl2-treated LoVo and Hct116 cells. After CoCl2 treatment, an increased expression of Cdc42 and PAK1 led to a decrease in the expression of stathmin and an increase in the expression of phosphorylated stathmin, which is located in the nucleus of PGCCs and progeny cells. PTPN14 negatively regulates the expression of PAK1 and p38MAPK. Low levels of PTPN14 expression, a downstream regulatory protein of stathmin, endows progeny tumor cells generated by PGCCs with the ability to invade and metastasize. The expression of PKA1α, cathepsin B, and D increased in CoCl2-treated cells compared with that in the control cells, associated with the infiltration and migration of PGCCs with their progeny cells.
Conclusion: CoCl2-induced overexpression of Cdc42 plays a critical role in increasing the infiltration and migration abilities of PGCCs and progeny cells by regulating cytoskeleton protein expression.
Keywords: PGCCs, Cdc42, stathmin, PAK1, cathepsin B, cathepsin D