A Novel ASCT2 Inhibitor, C118P, Blocks Glutamine Transport and Exhibits Antitumour Efficacy in Breast Cancer

Simple Summary ASCT2 is an attractive tumour metabolism target based on its critical role in cancer cell growth. The potential mechanisms of microtubule protein inhibitor C118P in breast cancer remain unknown. Identification of the potential target of C118P is essential. We evaluated the inhibitory effects of C118P on breast cancer. C118P restrained the tumour growth of MDA-MB-231 cells by inducing apoptosis, G2/M phase arrest, and autophagy. Furthermore, ASCT2 was confirmed to be a target of C118P. This is the first report to provide evidence that ASCT2 might be a candidate target of C118P in breast cancer treatment. Remarkably, this study will provide an opportunity for ASCT2 inhibition as a therapeutic strategy.Abstract Background: The microtubule protein inhibitor C118P shows excellent anti-breast cancer effects. However, the potential targets and mechanisms of C118P in breast cancer remain unknown. Methods: Real-time cellular analysis (RTCA) was used to detect cell viability. Apoptosis and the cell cycle were detected by flow cytometry. Computer docking simulations, surface plasmon resonance (SPR) technology, and microscale thermophoresis (MST) were conducted to study the interaction between C118P and alanine-serine-cysteine transporter 2 (ASCT2). Seahorse XF technology was used to measure the basal oxygen consumption rate (OCR). The effect of C118P in the adipose microenvironment was explored using a co-culture model of adipocytes and breast cancer cells and mouse cytokine chip. Results: C118P inhibited proliferation, potentiated apoptosis, and induced G2/M cell cycle arrest in breast cancer cells. Notably, ASCT2 was validated as a C118P target through reverse docking, SPR, and MST. C118P suppressed glutamine metabolism and mediated autophagy via ASCT2. Similar results were obtained in the adipocyte-breast cancer microenvironment. Adipose-derived interleukin-6 (IL-6) promoted the proliferation of breast cancer cells by enhancing glutamine metabolism via ASCT2. C118P inhibited the upregulation of ASCT2 by inhibiting the effect of IL-6 in co-cultures. Conclusion: C118P exerts an antitumour effect against breast cancer via the glutamine transporter ASCT2.