BRAFV600E mutations occur in ∼10% of colorectal cancer cases, are associated with poor survival, and have limited responses to BRAF/MEK inhibition with or without EGFR inhibition. There is an unmet need to understand the biology of poor prognostic BRAFMT colorectal cancer. We have used differential gene expression and pathway analyses of untreated stage II and stage III BRAFMT (discovery set: n = 31; validation set: n = 26) colorectal cancer, and an siRNA screen to characterize the biology underpinning the BRAFMT subgroup with poorest outcome. These analyses identified the unfolded protein response (UPR) as a novel and druggable pathway associated with the BRAFMT colorectal cancer subgroup with poorest outcome. We also found that oncogenic BRAF drives endoplasmic reticulum (ER) stress and UPR pathway activation through MEK/ERK. Furthermore, inhibition of GRP78, the master regulator of the UPR, using siRNA or small molecule inhibition, resulted in acute ER stress and apoptosis, in particular in BRAFMT colorectal cancer cells. In addition, dual targeting of protein degradation using combined Carfilzomib (proteasome inhibitor) and ACY-1215 (HDAC6-selective inhibitor) treatment resulted in marked accumulation of protein aggregates, acute ER stress, apoptosis, and therapeutic efficacy in BRAFMT in vitro and xenograft models. Mechanistically, we found that the apoptosis following combined Carfilzomib/ACY-1215 treatment is mediated through increased CHOP expression. Taken together, our findings indicate that oncogenic BRAF induces chronic ER stress and that inducers of acute ER stress could be a novel treatment strategy for poor prognostic BRAFMT colorectal cancer. Mol Cancer Ther; 17(6); 1280-90. ©2018 AACR.

• MeSH
• apoptóza účinky léků   genetika   MeSH
• biologické modely MeSH
• chaperon endoplazmatického retikula BiP MeSH
• inhibitory proteinkinas farmakologie   MeSH
• kolorektální nádory farmakoterapie   genetika   metabolismus   mortalita   MeSH
• kyseliny hydroxamové farmakologie   MeSH
• lidé MeSH
• MAP kinasový signální systém MeSH
• mutace * MeSH
• nádorové biomarkery MeSH
• nádorové buněčné linie MeSH
• oligopeptidy farmakologie   MeSH
• prognóza MeSH
• proteiny teplotního šoku genetika   metabolismus   MeSH
• proteosyntéza MeSH
• protinádorové látky farmakologie   MeSH
• protoonkogenní proteiny B-Raf antagonisté a inhibitory   genetika   metabolismus   MeSH
• pyrimidiny farmakologie   MeSH
• signální dráha UPR účinky léků   MeSH
• signální transdukce účinky léků   MeSH
• stres endoplazmatického retikula účinky léků   genetika   MeSH
• transkripční faktor CHOP genetika   metabolismus   MeSH
• viabilita buněk účinky léků   genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• carfilzomib MeSH Prohlížeč
• chaperon endoplazmatického retikula BiP MeSH
• DDIT3 protein, human MeSH Prohlížeč
• HSPA5 protein, human MeSH Prohlížeč
• inhibitory proteinkinas MeSH
• kyseliny hydroxamové MeSH
• nádorové biomarkery MeSH
• oligopeptidy MeSH
• proteiny teplotního šoku MeSH
• protinádorové látky MeSH
• protoonkogenní proteiny B-Raf MeSH
• pyrimidiny MeSH
• ricolinostat MeSH Prohlížeč
• transkripční faktor CHOP MeSH

MEK kinase inhibitors (trametinib and selumetinib) or kinase inhibitors directed against mutated BRAF(V600E) (vemurafenib and dabrafenib) have initial encouraging effects in the treatment of melanoma but acquired resistance appears almost invariably after some months. Studies revealed mutually exclusive NRAS and BRAF activating mutations driving the MAPK/ERK pathway among human melanomas. Although combination therapy exerts significantly better antitumor cell efficacy, complete remission is rarely achieved. To employ an alternative approach, we have targeted the Hedgehog/GLI pathway, which is deregulated in melanomas, through the GLI1/2 inhibitor GANT61, alone or accompanied with the treatment by the BCL2 family inhibitor obatoclax in 9 melanoma cell lines. Thus, we targeted melanoma cells irrespective of their NRAS or BRAF mutational status. After GANT61 treatment, the cell viability was drastically diminished via apoptosis, as substantial nuclear DNA fragmentation was detected. In all tested melanoma cell lines, the combined treatment was more efficient than the application of each drug alone at the end of the cell growth with inhibitors. GANT61 was efficient also alone in most cell lines without the addition of obatoclax, which had only a limited effect when used as a single drug. In most cell lines, tumor cells were eradicated after 5-9 days of combined treatment in colony outgrowth assay. To conclude, GANT61 treatment might become a hopeful and effective anti-melanoma targeted therapy, especially when combined with the BCL2 family inhibitor obatoclax.

• MeSH
• GTP-fosfohydrolasy genetika   MeSH
• indoly MeSH
• jaderné proteiny antagonisté a inhibitory   metabolismus   MeSH
• lidé MeSH
• melanom farmakoterapie   genetika   metabolismus   MeSH
• membránové proteiny genetika   MeSH
• mutace MeSH
• nádorové buněčné linie MeSH
• proliferace buněk účinky léků   MeSH
• protein Gli2 s motivem zinkových prstů MeSH
• protinádorové látky farmakologie   MeSH
• protoonkogenní proteiny B-Raf genetika   MeSH
• pyridiny farmakologie   MeSH
• pyrimidiny farmakologie   MeSH
• pyrroly farmakologie   MeSH
• synergismus léků MeSH
• transkripční faktory Krüppel-like antagonisté a inhibitory   metabolismus   MeSH
• viabilita buněk účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• BRAF protein, human MeSH Prohlížeč
• GANT 61 MeSH Prohlížeč
• GLI2 protein, human MeSH Prohlížeč
• GTP-fosfohydrolasy MeSH
• indoly MeSH
• jaderné proteiny MeSH
• membránové proteiny MeSH
• NRAS protein, human MeSH Prohlížeč
• obatoclax MeSH Prohlížeč
• protein Gli2 s motivem zinkových prstů MeSH
• protinádorové látky MeSH
• protoonkogenní proteiny B-Raf MeSH
• pyridiny MeSH
• pyrimidiny MeSH
• pyrroly MeSH
• transkripční faktory Krüppel-like MeSH