[PDF][PDF] HIF-mediated suppression of DEPTOR confers resistance to mTOR kinase inhibition in renal cancer

H Doan, A Parsons, S Devkumar, J Selvarajah… - Iscience, 2019 - cell.com
H Doan, A Parsons, S Devkumar, J Selvarajah, F Miralles, VA Carroll
Iscience, 2019cell.com
Mechanistic target of rapamycin (mTOR) is a fundamental regulator of cell growth,
proliferation, and metabolism. mTOR is activated in renal cancer and accelerates tumor
progression. Here, we report that the mTOR inhibitor, DEP domain-containing mTOR-
interacting protein (DEPTOR), is strikingly suppressed in clear cell renal cell carcinoma
(ccRCC) tumors and cell lines. We demonstrate that DEPTOR is repressed by both hypoxia-
inducible factors, HIF-1 and HIF-2, which occurs through activation of the HIF-target gene …
Summary
Mechanistic target of rapamycin (mTOR) is a fundamental regulator of cell growth, proliferation, and metabolism. mTOR is activated in renal cancer and accelerates tumor progression. Here, we report that the mTOR inhibitor, DEP domain-containing mTOR-interacting protein (DEPTOR), is strikingly suppressed in clear cell renal cell carcinoma (ccRCC) tumors and cell lines. We demonstrate that DEPTOR is repressed by both hypoxia-inducible factors, HIF-1 and HIF-2, which occurs through activation of the HIF-target gene and transcriptional repressor, BHLHe40/DEC1/Stra13. Restoration of DEPTOR- and CRISPR/Cas9-mediated knockout experiments demonstrate that DEPTOR is growth inhibitory in ccRCC. Furthermore, loss of DEPTOR confers resistance to second-generation mTOR kinase inhibitors through deregulated mTORC1 feedback to IRS-2/PI3K/Akt. This work reveals a hitherto unknown mechanism of resistance to mTOR kinase targeted therapy that is mediated by HIF-dependent reprograming of mTOR/DEPTOR networks and suggests that restoration of DEPTOR in ccRCC will confer sensitivity to mTOR kinase therapeutics.
cell.com