Characterizing the role of CYP2J2 in clear cell renal cell carcinoma and TKI-mediated cardiotoxicity

Abstract

CYP2J2 is the only member of the human CYP2J family, and its expression is largely extrahepatic. The highest expression of human CYP2J2 is in the heart, where its major endogenous function as an arachidonic acid (AA) epoxygenase has been widely investigated. Unlike CYP2Cs, which are other major epoxygenases involved in AA metabolism, CYP2J2 has been shown to form an equal ratio of all four regioisomers of epoxyeicosatrienoic acids (EETs), which are associated with cardioprotection. In addition to its better-recognized role as cardioprotective compounds, EETs are promoters of tumor angiogenesis and, collectively with CYP2J2 expression, have been positively associated with promoting the neoplastic tumor phenotype in numerous cell systems (1). The involvement of CYPs in tumorigenesis is not a novel finding. However, a major gap remains in characterizing the role of CYPs, including CYP2J2, during the development and progression of various cancers. The basal expression of CYP2J2 in the human kidney is low but transcriptomic studies by The Cancer Genome Atlas revealed the mRNA level of CYP2J2 is selectively overexpressed in clear cell renal cell carcinoma (ccRCC). ccRCC is the most common kidney cancer diagnosed in the U.S. and is among the top ten diagnosed cancers. Tumor angiogenesis is one major driver of ccRCC progression. Therefore, investigating CYP2J2 overexpression and EETs in ccRCC to better understand the effect on ccRCC progression would identify a novel role for CYP2J2 in kidney cancer. The current dissertation characterized the role of CYP2J2 in matched ccRCC and normal adjacent tissues and identified changes in the AA pathway using a multi-omics approach. CYP-mediated AA metabolites were also quantified to understand the implication of the altered AA pathway in ccRCC. The cardioprotective effect of CYP2J2 and 11,12-EET against tyrosine kinase inhibitor (TKI) mediated toxicity was also investigated in this dissertation. TKIs are first- and second-line chemotherapy drugs for ccRCC, but most TKIs on the market are associated with at least one presentation of an adverse cardiac event. The cardiotoxicity of TKIs could result in poor adherence to TKI therapy or cessation of treatment resulting in poor treatment efficacy (2). For this study, we selected a panel of TKIs based on literature reports of cardiotoxicity which ranged from having no reported incidence of cardiotoxicity to a black box warning for sudden death due to an adverse cardiac event. The addition of exogenous 11,12-EET in primary human cardiomyocytes following the silencing of CYP2J2 mRNA expression protected the cells against TKI toxicity compared to the vehicle. We also performed transcriptomics to characterize altered pathways in the presence of 11,12-EET during TKI injury which is reported in Chapter 3. Overall, we investigated the role of CYP2J2 and EETs in two disease states and highlight the dual effect of CYP2J2 expression in this dissertation. References 1. J. G. Jiang et al., Cytochrome P450 2J2 Promotes the Neoplastic Phenotype of Carcinoma Cells and Is Up-regulated in Human Tumors. Cancer Research 65, 4707-4715 (2005). 2. M. Chaar, J. Kamta, S. Ait-Oudhia, Mechanisms, monitoring, and management of tyrosine kinase inhibitors–associated cardiovascular toxicities. OncoTargets and therapy 11, 6227-6227 (2018).