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Updated: Aug 11, 2026
Spatial and Temporal Control of Murine Melanoma Initiation from Mutant Melanocyte Stem Cells
Published on: June 7, 2019
Regression of melanoma in a murine model by RLIP76 depletion
Sharad S Singhal1, Yogesh C Awasthi, Sanjay Awasthi
1Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington 76019-0065, USA.
Abstract:
RLIP76/RALBP1 is a stress-responsive membrane protein implicated in the regulation of multiple cellular signaling pathways. It represents the predominant glutathione-conjugate transporter in cells, and our previous studies have shown that its inhibition by antibodies or depletion by short interfering RNA (siRNA) causes apoptosis in a number of cancer cell types. The present studies were done to explore the potential clinical applicability of our previous observations by comparing the relative expression of RLIP76 in cancer versus normal cell lines and to determine whether depletion of RLIP76 activity can exert cancer-specific apoptosis. RLIP76 expression was found to be significantly greater in malignant cells compared to nonmalignant cells. Inhibition of RLIP76, using antibodies towards a cell surface epitope, or depletion of RLIP76 using either siRNA or antisense phosphorothioate oligonucleotides preferentially caused apoptosis in malignant cells. More importantly, in vivo studies showed that administration of RLIP76 antibodies, siRNA, or antisense oligonucleotides to mice bearing syngeneic B16 mouse melanoma cells caused complete tumor regression within 10 days. These findings strongly suggest that RLIP76 depletion by genetic approaches or inhibition by antibodies may be a clinically viable antineoplastic therapy, particularly for melanoma.
Insights
RLIP76 (RALBP1) is overexpressed in cancer cells. Inhibiting RLIP76 with antibodies or genetic methods triggers cancer-specific apoptosis and tumor regression, suggesting a potential melanoma therapy.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- RLIP76/RALBP1 is a stress-responsive membrane protein and the main glutathione-conjugate transporter.
- Previous studies indicated RLIP76 inhibition induces apoptosis in cancer cells.
Purpose of the Study:
- To compare RLIP76 expression in cancer vs. normal cells.
- To determine if RLIP76 depletion causes cancer-specific apoptosis.
- To explore RLIP76 as a potential antineoplastic therapy.
Main Methods:
- Compared RLIP76 expression in malignant and nonmalignant cell lines.
- Inhibited RLIP76 using antibodies, siRNA, and antisense oligonucleotides.
- Administered RLIP76 inhibitors to mice with melanoma tumors.
Main Results:
- RLIP76 expression was significantly higher in malignant cells.
- RLIP76 inhibition preferentially induced apoptosis in cancer cells.
- In vivo studies showed complete tumor regression in melanoma models within 10 days.
Conclusions:
- RLIP76 is upregulated in cancer cells.
- Targeting RLIP76 induces cancer-specific apoptosis and tumor regression.
- RLIP76 inhibition represents a promising antineoplastic strategy, especially for melanoma.
