RALB GTPase: a critical regulator of DR5 expression and TRAIL sensitivity in KRAS mutant colorectal cancer

RAS mutant (MT) metastatic colorectal cancer (mCRC) is resistant to MEK1/2 inhibition and remains a difficult-to-treat group. Therefore, there is an unmet need for novel treatment options for RAS MT mCRC. RALA and RALB GTPases function downstream of RAS and have been found to be key regulators of se...

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Bibliographic Details
Published in:Cell death & disease Vol. 11; no. 10; p. 930
Main Authors: Khawaja, Hajrah, Campbell, Andrew, Roberts, Jamie Z., Javadi, Arman, O’Reilly, Paul, McArt, Darragh, Allen, Wendy L., Majkut, Joanna, Rehm, Markus, Bardelli, Alberto, Di Nicolantonio, Federica, Scott, Christopher J., Kennedy, Richard, Vitale, Nicolas, Harrison, Timothy, Sansom, Owen J., Longley, Daniel B., Evergren, Emma, Van Schaeybroeck, Sandra
Format: Journal Article
Language:English
Published: London Nature Publishing Group UK 29.10.2020
Springer Nature B.V
Nature Publishing Group
Subjects:
13/2
13/31
13/89
14/19
38/109
38/79
42/70
631/67/1504/1885/1393
631/67/395
631/80/82/23
82/80
96/106
96/95
Antibodies
Antineoplastic Combined Chemotherapy Protocols - pharmacology
Apoptosis
Benzimidazoles - administration & dosage
Biochemistry
Biomedical and Life Sciences
Cancer
Caspase-8
Cell Biology
Cell Culture
Cell death
Cell surface
Cellular Biology
Colorectal cancer
Colorectal carcinoma
Colorectal Neoplasms - drug therapy
Colorectal Neoplasms - genetics
Colorectal Neoplasms - metabolism
DR5 protein
GTP Phosphohydrolases - metabolism
Humans
Immunology
K-Ras protein
Life Sciences
Lysosomes
Metastases
mRNA
Mutants
Mutation
Proto-Oncogene Proteins p21(ras) - genetics
Proto-Oncogene Proteins p21(ras) - metabolism
ral GTP-Binding Proteins - antagonists & inhibitors
ral GTP-Binding Proteins - biosynthesis
ral GTP-Binding Proteins - genetics
ral GTP-Binding Proteins - metabolism
RalA protein
Ras protein
Receptors, TNF-Related Apoptosis-Inducing Ligand - agonists
Receptors, TNF-Related Apoptosis-Inducing Ligand - metabolism
Recombinant Proteins - pharmacology
RNA, Messenger - genetics
RNA, Messenger - metabolism
RNA-mediated interference
Signal transduction
TNF-Related Apoptosis-Inducing Ligand - administration & dosage
TNF-Related Apoptosis-Inducing Ligand - pharmacology
Transfection
Tumorigenesis
ISSN:2041-4889, 2041-4889
Online Access:Get full text
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Summary:RAS mutant (MT) metastatic colorectal cancer (mCRC) is resistant to MEK1/2 inhibition and remains a difficult-to-treat group. Therefore, there is an unmet need for novel treatment options for RAS MT mCRC. RALA and RALB GTPases function downstream of RAS and have been found to be key regulators of several cell functions implicated in KRAS-driven tumorigenesis. However, their role as regulators of the apoptotic machinery remains to be elucidated. Here, we found that inhibition of RALB expression, but not RALA, resulted in Caspase-8-dependent cell death in KRAS MT CRC cells, which was not further increased following MEK1/2 inhibition. Proteomic analysis and mechanistic studies revealed that RALB depletion induced a marked upregulation of the pro-apoptotic cell surface TRAIL Death Receptor 5 (DR5) (also known as TRAIL-R2), primarily through modulating DR5 protein lysosomal degradation. Moreover, DR5 knockdown or knockout attenuated siRALB-induced apoptosis, confirming the role of the extrinsic apoptotic pathway as a regulator of siRALB-induced cell death. Importantly, TRAIL treatment resulted in the association of RALB with the death-inducing signalling complex (DISC) and targeting RALB using pharmacologic inhibition or RNAi approaches triggered a potent increase in TRAIL-induced cell death in KRAS MT CRC cells. Significantly, high RALB mRNA levels were found in the poor prognostic Colorectal Cancer Intrinsic Subtypes (CRIS)-B CRC subgroup. Collectively, this study provides to our knowledge the first evidence for a role for RALB in apoptotic priming and suggests that RALB inhibition may be a promising strategy to improve response to TRAIL treatment in poor prognostic RAS MT CRIS-B CRC.
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PMCID: PMC7596570
ISSN:2041-4889
2041-4889
DOI:10.1038/s41419-020-03131-3