The dramatic responses observed in patients with BRAF mutant melanoma treated with BRAF inhibitors reflect a major therapeutic breakthrough in melanoma. However, there are multiple resistance mechanisms that arise in patient tumors that limit the effectiveness of BRAF inhibitors. We have found that autophagy is activated in patient tumors and cell lines treated with BRAF inhibitors, and this therapy-associated autophagy protects melanoma cells and contributes to regrowth of tumors. Our previous work establishes that BRAF inhibitors activate autophagy by activating an early ER stress response which in turn gives rise to cytoprotective autophagy. In this proposal, the PI will work closely with the co-investigator, combining their respective expertise in autophagy, melanoma biology and treatment, and the ER stress response to elucidate the mechanistic underpinnings of the mutant BRAF-ER stress-autophagy signaling. Our hypothesis is that certain components of the ER stress pathway are critical for BRAF inhibitor-induced autophagy, and therefore could serve as novel targets for combinations regimens. Our strategy will be to first determine the molecular mechanism that links mutant BRAF with the ER stress response and autophagy (aim 1); then elucidate the biological effects of targeting specific components of the ER stress response or autophagy in BRAFi-induced cell death in 2D and 3D melanoma culture (aim 2); and to characterize the role of BRAFi-induced ER stress and autophagy in vivo using genetic and pharmacological inhibition of ER stress or autophagy in combination with BRAF inhibition (aim 3). The focus of these studies is on the development of a sophisticated understanding of the mechanistic links between these three pathways. The knowledge gained from these studies will increase our understanding about the fundamental biology of BRAF mutant melanoma, the interaction between mutant BRAF and the ER stress response, the role of cytoplasmic GRP78 in the response to targeted therapy, and the mechanisms by which the ER stress response regulates autophagy. Besides these fundamental advances, this project has translational potential because it will investigate these pathways in an enrolling trial of BRAF and autophagy inhibition in BRAF mutant melanoma patients, and it will identify potential new combinations that may be even more effective for future clinical trials.

Public Health Relevance

The Unfolded Protein Response (UPR)- associated autophagy pathway is a new resistance mechanism to targeted therapy. This study will unravel the molecular mechanisms that connect targeted therapy, the UPR, and autophagy. Knowledge gained would have an immediate impact on the treatment of BRAF mutant melanoma patients, but also could have an impact on patients with other cancers for which targeted therapies are used.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA198015-02
Application #
9131669
Study Section
Basic Mechanisms of Cancer Therapeutics Study Section (BMCT)
Program Officer
Arya, Suresh
Project Start
2015-09-01
Project End
2020-08-31
Budget Start
2016-09-01
Budget End
2017-08-31
Support Year
2
Fiscal Year
2016
Total Cost
Indirect Cost
Name
University of Pennsylvania
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Ojha, Rani; Leli, Nektaria M; Onorati, Angelique et al. (2018) ER translocation of the MAPK pathway drives therapy resistance in BRAF mutant melanoma. Cancer Discov :
Nicastri, Michael C; Rebecca, Vito W; Amaravadi, Ravi K et al. (2018) Dimeric quinacrines as chemical tools to identify PPT1, a new regulator of autophagy in cancer cells. Mol Cell Oncol 5:e1395504
Nti, Akosua A; Serrano, Leona W; Sandhu, Harpal S et al. (2018) FREQUENT SUBCLINICAL MACULAR CHANGES IN COMBINED BRAF/MEK INHIBITION WITH HIGH-DOSE HYDROXYCHLOROQUINE AS TREATMENT FOR ADVANCED METASTATIC BRAF MUTANT MELANOMA: Preliminary Results From a Phase I/II Clinical Treatment Trial. Retina :
Onorati, Angelique V; Dyczynski, Matheus; Ojha, Rani et al. (2018) Targeting autophagy in cancer. Cancer 124:3307-3318
Noguera-Ortega, Estela; Amaravadi, Ravi K (2018) Autophagy in the Tumor or in the Host: Which Plays a Greater Supportive Role? Cancer Discov 8:266-268
Rebecca, Vito W; Nicastri, Michael C; Fennelly, Colin et al. (2018) PPT1 promotes tumor growth and is the molecular target of chloroquine derivatives in cancer. Cancer Discov :
Garman, Bradley; Anastopoulos, Ioannis N; Krepler, Clemens et al. (2017) Genetic and Genomic Characterization of 462 Melanoma Patient-Derived Xenografts, Tumor Biopsies, and Cell Lines. Cell Rep 21:1936-1952
Piao, Shengfu; Ojha, Rani; Rebecca, Vito W et al. (2017) ALDH1A1 and HLTF modulate the activity of lysosomal autophagy inhibitors in cancer cells. Autophagy 13:2056-2071
Rebecca, Vito W; Nicastri, Michael C; McLaughlin, Noel et al. (2017) A Unified Approach to Targeting the Lysosome's Degradative and Growth Signaling Roles. Cancer Discov 7:1266-1283
Ojha, Rani; Amaravadi, Ravi K (2017) Targeting the unfolded protein response in cancer. Pharmacol Res 120:258-266

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