Abstract 2957: Inhibition of glutaminase induces slows tumor growth cell autonomously and promotes survival in a MYC driven hepatocellular carcinoma mouse model
Authors: Stine Zachary , Xiang Yan , Xia Jinsong , Gao Ping , Dinavahi Ramani , Dang Chi V. 
Published: May 2015

Glutamine catabolism has been shown to be critical in many cancer types, particularly in MYC dependent tumor types. Given that MYC dependent cell lines have been shown to be dependent on glutamine for growth and survival, we hypothesize that inhibiting glutamine metabolism could slow the growth of MYC driven tumors in vivo. Small molecule (BPTES) inhibition of kidney-type glutaminase (GLS) is being developed as an anti-cancer therapy, yet basic questions remained unanswered about glutamine inhibition. The BPTES insensitive liver-type glutaminase (GLS2) has been proposed to act as a tumor suppressor in liver cancer cell lines. We have found that hepatocellular carcinomas downregulate GLS2 and upregulate GLS compared to surrounding tissue in both humans and mice, leaving hepatocellular carcinomas potentially sensitive to GLS inhibition. BPTES slows the growth of hepatocellular carcinoma cell lines in vitro. Here were report the first study that demonstrates the ability of BPTES to slow tumor progression in genetic cancer models in immunocompetent mice, showing the BPTES prolongs survival of mice in a MYC driven hepatocellular carcinoma model. However, we could not determine from these data if the anti-cancer effects of GLS inhibition in vivo were systemic or cell autonomous, causing us to switch to a xenograft system. Using prostate and lymphoma cell lines overexpressing the BPTES resistant GLS K325A mutant, we show that BPTES functions through on-target inhibition of GLS in vitro. We then used a p493-6 B-cell lymphoma cell line to determine the cell autonomous effects of BPTES in vivo. P493-6 xenograft growth was slowed by BPTES treatment, while p493 xenografts overexpressing either wild type GLS or BPTES resistant GLS K325A were not slowed by BPTES treatment in vivo. We then set out to develop an alternative method to perform tumor specific knock down GLS in vivo to obtain genetic evidence of the role of GLS in tumor cells, developing a human specific vivo-morpholino that targets GLS for nonsense-mediated decay. Consistent with the effect of BPTES on tumor cells, the human GLS targeting vivo-morpholino slowed p493-6 xenograft growth in vivo. As the vivo-morpholino knockdown of GLS was xenograft specific, it demonstrates that GLS inhibition slows cancer growth through cancer cell autonomous methods and not though systemic changes that alter the tumor niche. In summary, we find that BPTES exhibits on target GLS inhibition in vivo to prolong survival in mouse hepatocellular carcinoma mouse models.

Citation Format: Zachary Stine, Yan Xiang, Jinsong Xia, Ping Gao, Ramani Dinavahi, Chi V. Dang. Inhibition of glutaminase induces slows tumor growth cell autonomously and promotes survival in a MYC driven hepatocellular carcinoma mouse model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2957. doi:10.1158/1538-7445.AM2014-2957