Figure 10.

Proposed model for the mechanism of action underlying the promotion of tumor progression by testis‐specific protein, Y‐linked 1 (TSPY1). The ectopic expression of TSPY1 in cancer cells downregulates the mRNA expression of the insulin growth factor binding protein 3 (IGFBP3) gene as a transcription suppressor by occupying its promotion region. The decrease in the level of IGFBP3 protein in the cell reduces its extracellular secretions and impairs its capability that sequesters insulin‐like growth factor 1 (IGF1) from IGF1 receptor (IGF1R). Augmenting of the IGF1/IGF1R‐mediated signal activates both PI3K/AKT and RAS signaling pathways and upregulates the expression of BCL‐2, p‐mTOR, p‐ERK, and JUN. The enhancement of functions of these 4 proteins facilitates cell proliferation, cycle transition, and invasion and inhibits cell apoptosis, probably promoting tumor progression