RLIP depletion induces apoptosis associated with inhibition of JAK2/STAT3 signaling in melanoma cells

Carcinogenesis. 2021 May 28;42(5):742-752. doi: 10.1093/carcin/bgab016.

Abstract

The incidence of malignant melanoma, a neoplasm of melanocytic cells, is increasing rapidly. The lymph nodes are often the first site of metastasis and can herald systemic dissemination, which is almost uniformly fatal. RLIP, a multi-specific ATP-dependent transporter that is over-expressed in several types of cancers, plays a central role in cancer cell resistance to radiation and chemotherapy. RLIP appears to be necessary for cancer cell survival because both in vitro cell culture and in vivo animal tumor studies show that the depletion or inhibition of RLIP causes selective toxicity to malignant cells. RLIP depletion/inhibition triggers apoptosis in cancer cells by inducing the accumulation of endogenously formed glutathione-conjugates. In our in vivo studies, we administered RLIP antibodies or antisense oligonucleotides to mice bearing subcutaneous xenografts of SKMEL2 and SKMEL5 melanoma cells and demonstrated that both treatments caused significant xenograft regression with no apparent toxic effects. Anti-RLIP antibodies and antisense, which respectively inhibit RLIP-mediated transport and deplete RLIP expression, showed similar tumor regressing activities, indicating that the inhibition of RLIP transport activity at the cell surface is sufficient to achieve anti-tumor activity. Furthermore, RLIP antisense treatment reduced levels of RLIP, pSTAT3, pJAK2, pSrc, Mcl-1 and Bcl2, as well as CDK4 and cyclin B1, and increased levels of Bax and phospho 5' AMP-activated protein kinase (pAMPK). These studies indicate that RLIP serves as a key effector in the survival of melanoma cells and is a valid target for cancer therapy. Overall, compounds that inhibit, deplete or downregulate RLIP will function as wide-spectrum agents to treat melanoma, independent of common signaling pathway mutations.

Publication types

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

MeSH terms

  • ATP-Binding Cassette Transporters / antagonists & inhibitors
  • ATP-Binding Cassette Transporters / genetics*
  • ATP-Binding Cassette Transporters / immunology
  • Animals
  • Antibodies, Anti-Idiotypic / pharmacology
  • Apoptosis / genetics
  • Cell Line, Tumor
  • Cell Survival / genetics
  • GTPase-Activating Proteins / antagonists & inhibitors
  • GTPase-Activating Proteins / genetics*
  • GTPase-Activating Proteins / immunology
  • Humans
  • Janus Kinase 2 / genetics*
  • Melanoma / genetics*
  • Melanoma / pathology
  • Mice
  • Neoplasm Proteins / genetics
  • STAT3 Transcription Factor / genetics*
  • Signal Transduction / genetics
  • Xenograft Model Antitumor Assays

Substances

  • ATP-Binding Cassette Transporters
  • Antibodies, Anti-Idiotypic
  • GTPase-Activating Proteins
  • Neoplasm Proteins
  • RALBP1 protein, human
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • JAK2 protein, human
  • Janus Kinase 2