Abstract 5285: The role of HIV-1 TAT interactive protein 2 in modulating tumor response to hypoxia

Abstract

Abstract While there is ample evidence that HIV-1 TAT interactive protein 2 (HTATIP2) is a tumor suppressor exerting its pro-apoptotic and anti-metastatic activities by regulating the expression of a subset of pro-apoptotic and anti-apoptotic genes and metastasis suppressor genes, it remains unclear if HTATIP2 has a role in tumor response to hypoxia. The objective of this study was to define the role of HTATIP2 in mediating certain molecular and cellular changes in response to hypoxia in tumors. We employed a series of isogenic A549 human lung adenocarcinoma sublines that were genetically deficient for HTATIP2 and/or HIF-1α to examine the potential modulatory effect of HTATIP2 on oncogenic signaling pathways mediated by HIF-1α and HIF-2α, and established the HTATIP2-deficient A549 xenograft model to explore the impact of deletion of HTATIP2 on tumor response to hypoxia. Results from the human HIF-regulated cDNA plate array study revealed that under hypoxic condition (0.5% O2), several genes promoting tumor metastasis and resistance to apoptosis and anticancer treatment, including HIF1α, CYSD, MMP1, MXI1, NDRG2, PAI1 and NDRG1, were upregulated to a greater extent in HTATIP2 knockdown A549 cells than in the control A549 cells. In contrast, genes involved in angiogenesis, glucose metabolism and protection of apoptosis under hypoxia, such as PDGF, PDK1, CA9, and SAG, were upregulated to a greater extent in control A549 cells than in HTATIP2-knockdown A549 cells. Results from the in vivo study demonstrated that the mean growth rate of HTATIP2-deficient A549 xenograft tumors was significantly increased as compared with that of parental A549 xenograft tumors irrespective of the presence or absence of sorafenib treatment. Moreover, the data of photoacoustic imaging (PAI) of tumor hypoxia revealed that the parental A549 tumors were better oxygenated than the counterpart HTATIP2-deficient A549 tumors. After the 10-day sorafenib treatment, the oxygenated regions in sorafenib-treated parental A549 tumors were significantly reduced as compared with the vehicle-treated parental A549 tumors, whereas no significant change in the oxygenated regions was found between vehicle- and sorafenib-treated HTATIP2-deficient A549 tumors. The overall finding of our study suggests that downregulation of HTATIP2 affords growth advantage to tumor cells by fine-tuning tumor adaptation to hypoxia, leading to tumor progression and aggression. Citation Format: Qingyu Stephanie Zhou, Xiaofang Guo, Minghua Li, Hua Pan. The role of HIV-1 TAT interactive protein 2 in modulating tumor response to hypoxia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5285.