Investigating the role of MCT1 in endometrial cancer

Abstract

Abstract Background: Endometrial cancer (EC) cells exhibit metabolic adaptability to survive in low-oxygen and nutrient-limited environments, utilizing resources like lactate, glucose and glutamine. This adaptability is essential for cancer cell survival, enabling tumour cells to thrive in challenging conditions. MCT1, a transporter for lactate and pyruvate, supports energy maintenance and growth by supporting metabolic reprogramming of cancer cells. MCT1 has been shown to have prognostic significance in various cancer types. Further, its subcellular localisation is shown to have an impact on overall survival in EC and soft-tissue sarcomas. Therefore, understanding the factors influencing MCT1 function and expression in EC is vital for exploiting this for patient benefit. This project aims to understand the effect of oxygen and nutrient availability on MCT1 expression and function, and expand the knowledge on the effect of nuclear MCT1 in EC. Methods: Ishikawa, HEC-1-A, and AN3-CA cell lines were used as models to investigate the role of MCT1 in EC. Various methods were employed to assess expression (Western blot, immunofluorescence), metabolic activity (MTT, Seahorse analysis, lactate, and ROS assays), and cellular functions (SRB, cell cycle analysis, and Annexin V staining) following MCT1 knockdown (KD) via siRNA or inhibition by AZD3965. These experiments were conducted under different oxygen conditions (21%, 3%, and 1%) and nutrient-limited environments (0 mM and 2 mM L-glutamine). Results: MCT1 KD led to a compensatory upregulation of MCT4, indicating a strong adaptive response to maintain lactate transport. Metabolic profiling revealed that the absence of L-glutamine significantly reduced mitochondrial respiration in Ishikawa cells, as demonstrated by decreased oxygen consumption rate (OCR). Functional analyses, including cell cycle assessment, apoptosis, and ROS measurements, showed distinct profiles resulting from MCT1 KD across the three cell lines and cells exhibited different responses to low oxygen. In addition to these functional analyses, like EC human biopsies, nuclear localisation of MCT1was observed in all three cell lines and was detected in the chromosome structure. Conclusions: The study offers important insights into the metabolic adaptations of EC cells in response to MCT1 inhibition/KD, hypoxic stress and glutamine-free environments. The findings underscore the potential of MCT1 as a therapeutic target to disrupt the metabolic flexibility of cancer cells, thereby impairing their survival and metastatic potential. Furthermore, the presence of MCT1 in the nucleus suggests a non-canonical function for this transporter.

Date of Award	1 Aug 2025
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Kaye Williams (Supervisor), Adam Hurlstone (Supervisor) & Ayse Latif (Supervisor)