GPCRomics : GPCR Expression in Cancer Cells and Tumors Identifies New, Potential Biomarkers and Therapeutic Targets

Financial support for these studies was provided by Roche, the Lymphoma and Leukemia Society, Friends of ANCHOR, an ASPET Astellas Award and grants from the National Institutes of Health, National Cancer Institute (CA189477, CA121938, CA155620). National Cancer Institute (NCI) Therapeutic Training Grant 5T32CA121938, NIH/NCI Research Grants R21 CA189477, an ASPET David Lehr Award and the Padres Pedal the Cause #PTC2017 award.Peer reviewedPublisher PD

G protein-coupled receptor expression and function in cancer and the cancer associated microenvironment : A study of Chronic Lymphocytic Leukemia and Pancreatic Adenocarcinoma

G protein-coupled receptors (GPCRs) are the largest superfamily of membrane receptors and are targeted by more than 30% of FDA-approved drugs. Although there has been limited study of GPCRs in cancer, they may be strategic targets in treating both tumor cells and the supportive microenvironment that is implicated in malignancies such as chronic lymphocytic leukemia (CLL) and pancreatic ductal adenocarcinoma (PDAC). In this thesis research, TaqMan® GPCR arrays were used as an unbiased approach to characterize the GPCR profile of CLL cells and NKtert bone marrow cells, as well as PDAC cells and pancreatic- cancer associated fibroblasts (CAFs). The results revealed that targeting two highly expressed Gs-linked GPCRs, VIPR1 and MC2R, in combination with the dual PDE inhibitor IR284, increased CLL cell death, presumably by increasing cellular cAMP levels. I characterized the GPCR profile of bone marrow NKtert cells and found that cAMP-mediated effects reduce NKtert cell viability and proliferation by modulation of protein kinase A (PKA) and the Exchange Protein activated by cAMP -1 (Epac-1), respectively. I determined that PDAC cells express 73 GPCRs whose expression was shared on three patient tumors, and 55 GPCRs shared between two patient-derived cell lines and two PDAC cell lines. Of these GPCRs, the Class C orphan GPRC5A was found to be the most highly expressed and up- regulated in PDAC cells relative to a normal pancreatic ductal epithelial cell line (HPDE6) and in CAFs compared to pre-fibroblast precursor cells (pancreatic stellate cells, PSC). Transfection of HPDE6 cells with GPRC5A enhanced DNA synthesis in the cells, indicating that GPRC5A may contribute to the malignant phenotype of PDAC and may be a novel therapeutic target for pancreatic cancer. Thus, I was able to characterize the expression of GPCRs in two types of cancer, in both the cancer cells themselves and in cells of their associated microenvironment. The findings provide new insights regarding GPCR expression in cancer and suggest new ways in which cancer cells interact with their surrounding microenvironmen

GPCRomics: GPCR Expression in Cancer Cells and Tumors Identifies New, Potential Biomarkers and Therapeutic Targets.

G protein-coupled receptors (GPCRs), the largest family of targets for approved drugs, are rarely targeted for cancer treatment, except for certain endocrine and hormone-responsive tumors. Limited knowledge regarding GPCR expression in cancer cells likely has contributed to this lack of use of GPCR-targeted drugs as cancer therapeutics. We thus undertook GPCRomic studies to define the expression of endoGPCRs (which respond to endogenous molecules such as hormones, neurotransmitters and metabolites) in multiple types of cancer cells. Using TaqMan qPCR arrays to quantify the mRNA expression of ∼340 such GPCRs, we found that human chronic lymphocytic leukemia (CLL) cells/stromal cells associated with CLL, breast cancer cell lines, colon cancer cell lines, pancreatic ductal adenocarcinoma (PDAC) cells, cancer associated fibroblasts (CAFs), and PDAC tumors express 50 to >100 GPCRs, including many orphan GPCRs (which lack known physiologic agonists). Limited prior data exist regarding the expression or function of most of the highly expressed GPCRs in these cancer cells and tumors. Independent results from public cancer gene expression databases confirm the expression of such GPCRs. We propose that highly expressed GPCRs in cancer cells (for example, GPRC5A in PDAC and colon cancer cells and GPR68 in PDAC CAFs) may contribute to the malignant phenotype, serve as biomarkers and/or may be novel therapeutic targets for the treatment of cancer

G Protein–Coupled Receptor (GPCR) Expression in Native Cells: “Novel” endoGPCRs as Physiologic Regulators and Therapeutic Targets

G protein–coupled receptors (GPCRs), the largest family of signaling receptors in the human genome, are also the largest class of targets of approved drugs. Are the optimal GPCRs (in terms of efficacy and safety) currently targeted therapeutically? Especially given the large number (∼120) of orphan GPCRs (which lack known physiologic agonists), it is likely that previously unrecognized GPCRs, especially orphan receptors, regulate cell function and can be therapeutic targets. Knowledge is limited regarding the diversity and identity of GPCRs that are activated by endogenous ligands and that native cells express. Here, we review approaches to define GPCR expression in tissues and cells and results from studies using these approaches. We identify problems with the available data and suggest future ways to identify and validate the physiologic and therapeutic roles of previously unrecognized GPCRs. We propose that a particularly useful approach to identify functionally important GPCRs with therapeutic potential will be to focus on receptors that show selective increases in expression in diseased cells from patients and experimental animals

GPCRomics: GPCR Expression in Cancer Cells and Tumors Identifies New, Potential Biomarkers and Therapeutic Targets

G protein-coupled receptors (GPCRs), the largest family of targets for approved drugs, are rarely targeted for cancer treatment, except for certain endocrine and hormone-responsive tumors. Limited knowledge regarding GPCR expression in cancer cells likely has contributed to this lack of use of GPCR-targeted drugs as cancer therapeutics. We thus undertook GPCRomic studies to define the expression of endoGPCRs (which respond to endogenous molecules such as hormones, neurotransmitters and metabolites) in multiple types of cancer cells. Using TaqMan qPCR arrays to quantify the mRNA expression of ∼340 such GPCRs, we found that human chronic lymphocytic leukemia (CLL) cells/stromal cells associated with CLL, breast cancer cell lines, colon cancer cell lines, pancreatic ductal adenocarcinoma (PDAC) cells, cancer associated fibroblasts (CAFs), and PDAC tumors express 50 to >100 GPCRs, including many orphan GPCRs (which lack known physiologic agonists). Limited prior data exist regarding the expression or function of most of the highly expressed GPCRs in these cancer cells and tumors. Independent results from public cancer gene expression databases confirm the expression of such GPCRs. We propose that highly expressed GPCRs in cancer cells (for example, GPRC5A in PDAC and colon cancer cells and GPR68 in PDAC CAFs) may contribute to the malignant phenotype, serve as biomarkers and/or may be novel therapeutic targets for the treatment of cancer