Basal cell carcinoma (BCC) is the most prevalent cancer in the world and nearly half of US citizens are likely to develop this cancer before retirement. BCCs are invasive epithelial tumors that originate from activating mutations in the Hedgehog (Hh) pathway, an essential developmental pathway that has been implicated in approximately 25% of all human cancer deaths. Despite the critical nature of Hh signaling, how Hh mediates the impressive proliferative defects in cancers remain poorly understood. Hh pathway activation begins when Hh ligand binds and inhibits transmembrane receptor Patched1, allowing signal transducer Smoothened (Smo) to activate Gli transcription factors and amplify expression of Hh target genes. Smo inhibitors have recently gained approval for treatment of late advanced or metastatic BCC and exhibit potent tumor regression. While these inhibitors are effective in nave tumors, aggressive tumors tend to develop early resistance to the drug, illustrating the need for new therapeutic targets. I have recently discovered that a critically important oncogene, atypical Protein Kinase C iota/lambda (aPKC-?/?), involved in stem cell fate choice during development of nearly all multicellular organisms is essential for high, sustained Hh pathway activation in BCCs. I have also shown pharmacological inhibition of aPKC suppresses murine BCC tumor growth and the growth of nave and Smo-resistant BCC cells. The goal of my research is to determine the mechanisms that allow the polarity protein aPKC-?/? to promote Hh pathway activation and nave and Smo-resistant BCC growth. During the K99 phase, I will determine how phosphorylation of Gli by aPKC-?/? alters target gene specificity to promote tumor growth, how BCC's regulate aPKC-?/? activity, and test the therapeutic potential of additional novel aPKC-?/? inhibitors for the treatment of nave and resistant BCC. During the R00 phase, I will determine how aPKC-?/? -dependent Gli1 responsive genes regulate tumor invasion and analyze aPKC-?/? function in Smo-resistant BCCs. The results of this study will reveal conserved mechanisms that govern cell polarity and Hh signaling during BCC that will prove invaluable in generating novel therapeutics for the treatment of Hh-dependent cancers.

Public Health Relevance

Basal cell carcinoma is the most common cancer in the world and is driven by Hedgehog pathway activation. My proposed work will reveal how polarity protein aPKC mediates Hedgehog pathway activation to induce basal cell carcinoma growth and provide a novel therapeutic target to treat Hedgehog- dependent cancers.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Transition Award (R00)
Project #
5R00CA176847-04
Application #
9056647
Study Section
Special Emphasis Panel (NSS)
Program Officer
Yassin, Rihab R
Project Start
2014-02-11
Project End
2018-04-30
Budget Start
2016-05-01
Budget End
2017-04-30
Support Year
4
Fiscal Year
2016
Total Cost
Indirect Cost
Name
University of California Irvine
Department
Anatomy/Cell Biology
Type
Schools of Arts and Sciences
DUNS #
046705849
City
Irvine
State
CA
Country
United States
Zip Code
92617
Drummond, Michael L; Li, Mischa; Tarapore, Eric et al. (2018) Actin polymerization controls cilia-mediated signaling. J Cell Biol 217:3255-3266
Whitson, Ramon J; Lee, Alex; Urman, Nicole M et al. (2018) Noncanonical hedgehog pathway activation through SRF-MKL1 promotes drug resistance in basal cell carcinomas. Nat Med 24:271-281
Mirza, Amar N; Fry, Micah A; Urman, Nicole M et al. (2017) Combined inhibition of atypical PKC and histone deacetylase 1 is cooperative in basal cell carcinoma treatment. JCI Insight 2:
Urman, Nicole M; Mirza, Amar; Atwood, Scott X et al. (2016) Tumor-Derived Suppressor of Fused Mutations Reveal Hedgehog Pathway Interactions. PLoS One 11:e0168031
Atwood, Scott X; Sarin, Kavita Y; Li, Jiang R et al. (2015) Rolling the Genetic Dice: Neutral and Deleterious Smoothened Mutations in Drug-Resistant Basal Cell Carcinoma. J Invest Dermatol 135:2138-2141
Jaju, Prajakta D; Nguyen, Christine B; Mah, Angela M et al. (2015) Mutations in the Kinetochore Gene KNSTRN in Basal Cell Carcinoma. J Invest Dermatol 135:3197-3200
Zhao, Xuesong; Ponomaryov, Tatyana; Ornell, Kimberly J et al. (2015) RAS/MAPK Activation Drives Resistance to Smo Inhibition, Metastasis, and Tumor Evolution in Shh Pathway-Dependent Tumors. Cancer Res 75:3623-35
Atwood, Scott X; Sarin, Kavita Y; Whitson, Ramon J et al. (2015) Smoothened variants explain the majority of drug resistance in basal cell carcinoma. Cancer Cell 27:342-53