Dataset Information

PLX8394, a new generation BRAF inhibitor, selectively inhibits BRAF in colonic adenocarcinoma cells and prevents paradoxical MAPK pathway activation.

ABSTRACT: BRAF inhibitors (BRAFi) are standard of care for the treatment of BRAF V600 mutation-driven metastatic melanoma, but can lead to paradoxical activation of the mitogen-activated protein kinase (MAPK) signalling pathway. This can result in the promotion of precancerous lesions and secondary neoplasms, mainly (but not exclusively) associated with pre-existing mutations in RAS genes. We previously reported a patient with synchronous BRAF-mutated metastatic melanoma and BRAF wt /KRAS G12D-metastatic colorectal cancer (CRC), whose CRC relapsed and progressed when treated with the BRAF inhibitor dabrafenib (GSK2118436). We used tissue from the resected CRC metastasis to derive a cell line, LM-COL-1, which directly and reliably mimicked the clinical scenario including paradoxical activation of the MAPK signalling pathway resulting in increased cell proliferation upon dabrafenib treatment. Novel BRAF inhibitors (PLX8394 and PLX7904), dubbed as "paradox breakers", were developed to inhibit V600 mutated oncogenic BRAF without causing paradoxical MAPK pathway activation. In this study we used our LM-COL-1 model alongside multiple other CRC cell lines with varying mutational backgrounds to demonstrate and confirm that the paradox breaker PLX8394 retains on-target inhibition of mutated BRAF V600 without paradoxically promoting MAPK signalling.

SUBMITTER: Tutuka CSA

PROVIDER: S-EPMC5490236 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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PLX8394, a new generation BRAF inhibitor, selectively inhibits BRAF in colonic adenocarcinoma cells and prevents paradoxical MAPK pathway activation.

Tutuka Candani S A CSA Andrews Miles C MC Mariadason John M JM Ioannidis Paul P Hudson Christopher C Cebon Jonathan J Behren Andreas A

Molecular cancer 20170628 1

BRAF inhibitors (BRAFi) are standard of care for the treatment of BRAF V600 mutation-driven metastatic melanoma, but can lead to paradoxical activation of the mitogen-activated protein kinase (MAPK) signalling pathway. This can result in the promotion of precancerous lesions and secondary neoplasms, mainly (but not exclusively) associated with pre-existing mutations in RAS genes. We previously reported a patient with synchronous BRAF-mutated metastatic melanoma and BRAF <sup>wt</sup> /KRAS <sup> ...[more]

PMID: 28659148

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Project description:The mitogen-activated protein kinase (MAPK) pathway plays a central role in colorectal cancers (CRC). In particular, BRAF V600E-mutant tumors, which represent around 10% of CRCs, are refractory to current therapies. Overexpression and secretion of serine peptidase inhibitor Kazal type 1 (SPINK1) are observed in around 50% of CRCs, and its serum level can be used as a biomarker for poor prognosis. Utilizing a recently developed extendable blocking probe assay, we analyzed the BRAF mutation status in a CRC patient cohort (N = 571) using tissue-derived RNA as the starting material. From the same RNA samples, we measured the relative SPINK1 expression levels using a quantitative real-time PCR method. Expression of mutant BRAF V600E correlated with poor prognosis, as did low expression of SPINK1 mRNA. Further, BRAF V600E correlated negatively with SPINK1 levels. In order to investigate the effect of MAPK pathway-targeted therapies on SPINK1 secretion, we conducted in vitro studies using both wild-type and V600E CRC cell lines. BRAF inhibitor vemurafenib, and subsequent MAPK pathway inhibitors trametinib and SCH772984, significantly increased SPINK1 secretion in V600E CRC cell lines Colo205 and HT-29 with a concomitant decrease in trypsin-1 and -2 secretion. Notably, no SPINK1 increase or trypsin-1 decrease was observed in BRAF wild-type CRC cell line Caco-2 in response to MAPK pathway inhibitors. In further mechanistic studies, we observed that only trametinib was able to diminish completely both MEK and ERK phosphorylation in the V600E CRC cells. Furthermore, the key regulator of integrated stress response, activating transcription factor 4 (ATF-4), was downregulated both at mRNA and at protein level in response to trametinib treatment. In conclusion, these data suggest that sustained inhibition of not only MAPK pathway activation, but also ATF-4 and trypsin, might be beneficial in the therapy of BRAF V600E-mutant CRC and that SPINK1 levels may serve as an indicator of therapy response.

Dataset Information

PLX8394, a new generation BRAF inhibitor, selectively inhibits BRAF in colonic adenocarcinoma cells and prevents paradoxical MAPK pathway activation.

Publications

PLX8394, a new generation BRAF inhibitor, selectively inhibits BRAF in colonic adenocarcinoma cells and prevents paradoxical MAPK pathway activation.

Similar Datasets

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