Abstract A020: Unraveling the role of ANO7 in prostate cancer metabolism
Authors: Sultana Nasrin , Lof Christoffer , Goel Neha , Schleutker Johanna 
Published: June 2023

Abstract
Prostate cancer (PCa), the most common male cancer worldwide, causes about 10% of cancer related deaths in Europe. It has a wide spectrum of clinical behavior that ranges from decades of indolence to rapid metastatic progression and lethality. However, the molecular mechanisms involved in aggressive PCa progression are still poorly understood. We have previously linked single-nucleotide polymorphisms in the anoctamin 7 (ANO7) gene to the risk of aggressive prostate cancer and shown that carriers of a rs77559646 variant have improved treatment response to docetaxel. The expression of ANO7 is lost when prostate cancer progresses and is completely lacking in prostate cancer metastases. ANO7 is a prostate specific gene and is highly expressed in the luminal cells of the human prostate. ANO7 belongs to a family of calcium-activated chloride channels and select members of the anoctamin family have phospholipid scramblase activity. Whether ANO7 has any of these capabilities is unclear. To uncover the cellular functions of ANO7 has proven challenging because the expression of ANO7 at protein level is either minimal or nonexistent in all commercially available cell lines. To overcome this and to study the cellular functions of ANO7, we have generated stable prostate cell lines overexpressing ANO7 using lentiviral transduction. The characterization of the RWPE-1 cells overexpressing ANO7 showed that the viability and proliferation was increased both in 2D and 3D. To gain information into what pathways ANO7 is affecting, we performed RNA-sequencing and pathway analysis. Interestingly, we found enrichment of mitochondrial genes participating in oxidative phosphorylation in cells overexpressing ANO7. The genes expressed from the mitochondrial genome were upregulated and the nuclear genes encoding for proteins involved in mitochondrial functions were mostly downregulated. This suggests that the mitochondrial metabolism has changed. We assessed the mitochondrial function by measuring the oxidative phosphorylation capability of the cells and showed that the maximal respiratory capacity of ANO7 overexpressing cells is indeed reduced compared to control cells. We also analyzed which of the three major mitochondrial fuels (glucose, glutamine and fatty acids) are not used as efficiently for oxidative phosphorylation in ANO7 overexpressing cells. The result proves that ANO7 cells are not utilizing glucose as effectively as control cells as there were no differences in maximal respiratory capacity when we treated the cells with the UK5099 inhibitor, which inhibits pyruvate import to mitochondria. Furthermore, preliminary results from the glycolysis stress assay indicates that glycolysis is increased in ANO7 overexpressing cells. In addition, electron microscopy study suggests that ANO7 overexpressing cells have less cristae compared to control. This study shows for the first time that ANO7 rewires prostate mitochondrial functions and thus cellular metabolism.
Citation Format: Nasrin Sultana, Christoffer Lof, Neha Goel, Johanna Schleutker. Unraveling the role of ANO7 in prostate cancer metabolism [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr A020.