PSMD10/gankyrin induces autophagy to promote tumor progression through cytoplasmic interaction with ATG7 and nuclear transactivation of ATG7 expression

ABSTRACTAlthough autophagy is most critical for survival of cancer cells, especially in fast-growing tumors, the mechanism remains to be fully characterized. Herein we report that PSMD10/gankyrin promotes autophagy in hepatocellular carcinoma (HCC) in response to starvation or stress through 2 complementary routes. PSMD10 was physically associated with ATG7 in the cytoplasm, and this association was enhanced by initial nutrient deprivation. Subsequently, PSMD10 translocated into the nucleus and bound cooperatively with nuclear HSF1 (heat shock transcription factor 1) onto the ATG7 promoter, upregulated ATG7 expression in the advanced stage of starvation. Intriguingly, the type of PSMD10-mediated autophagy was independent of the proteasome system, although PSMD10 has been believed to be an indispensable chaperone for assembly of the 26S proteasome. A significant correlation between PSMD10 expression and ATG7 levels was detected in human HCC biopsies, and the combination of these 2 parameters is a powerful ...