Heme oxygenase-1 promotes survival of renal cancer cells through modulation of apoptosis- and autophagy-regulating molecules

J Biol Chem. 2012 Sep 14;287(38):32113-23. doi: 10.1074/jbc.M112.393140. Epub 2012 Jul 26.

Abstract

The cytoprotective enzyme heme oxygenase-1 (HO-1) is often overexpressed in different types of cancers and promotes cancer progression. We have recently shown that the Ras-Raf-ERK pathway induces HO-1 to promote survival of renal cancer cells. Here, we examined the possible mechanisms underlying HO-1-mediated cell survival. Considering the growing evidence about the significance of apoptosis and autophagy in cancer, we tried to investigate how HO-1 controls these events to regulate survival of cancer cells. Rapamycin (RAPA) and sorafenib, two commonly used drugs for renal cancer treatment, were found to induce HO-1 expression in renal cancer cells Caki-1 and 786-O; and the apoptotic effect of these drugs was markedly enhanced upon HO-1 knockdown. Overexpression of HO-1 protected the cells from RAPA- and sorafenib-induced apoptosis and also averted drug-mediated inhibition of cell proliferation. HO-1 induced the expression of anti-apoptotic Bcl-xL and decreased the expression of autophagic proteins Beclin-1 and LC3B-II; while knockdown of HO-1 down-regulated Bcl-xL and markedly increased LC3B-II. Moreover, HO-1 promoted the association of Beclin-1 with Bcl-xL and Rubicon, a novel negative regulator of autophagy. Drug-induced dissociation of Beclin-1 from Rubicon and the induction of autophagy were also inhibited by HO-1. Together, our data signify that HO-1 is up-regulated in renal cancer cells as a survival strategy against chemotherapeutic drugs and promotes growth of tumor cells by inhibiting both apoptosis and autophagy. Thus, application of chemotherapeutic drugs along with HO-1 inhibitor may elevate therapeutic efficiency by reducing the cytoprotective effects of HO-1 and by simultaneous induction of both apoptosis and autophagy.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis Regulatory Proteins / biosynthesis
  • Apoptosis*
  • Autophagy*
  • Autophagy-Related Proteins
  • Beclin-1
  • Benzenesulfonates / pharmacology
  • Cell Line, Tumor
  • Cell Proliferation
  • Gene Expression Regulation, Neoplastic*
  • Heme Oxygenase-1 / metabolism*
  • Humans
  • Intracellular Signaling Peptides and Proteins / biosynthesis
  • Kidney Neoplasms / enzymology*
  • Kidney Neoplasms / pathology
  • Membrane Proteins / biosynthesis
  • Microtubule-Associated Proteins / biosynthesis
  • Niacinamide / analogs & derivatives
  • Phenylurea Compounds
  • Protoporphyrins / chemistry
  • Pyridines / pharmacology
  • Sirolimus / pharmacology
  • Sorafenib

Substances

  • Apoptosis Regulatory Proteins
  • Autophagy-Related Proteins
  • BECN1 protein, human
  • Beclin-1
  • Benzenesulfonates
  • Intracellular Signaling Peptides and Proteins
  • MAP1LC3B protein, human
  • Membrane Proteins
  • Microtubule-Associated Proteins
  • Phenylurea Compounds
  • Protoporphyrins
  • Pyridines
  • RUBCN protein, human
  • Niacinamide
  • Sorafenib
  • Heme Oxygenase-1
  • Sirolimus