Abstract 5602: Galactokinase 1 is a novel metabolic target against bladder cancer
Authors: Surya P. Singh, Chinthalapally V. Rao, Venkateshwar Madka
Journal: Cancer Research (2025)

Abstract Urinary bladder cancer (BCa) is the second most prevalent cancer of the genitourinary tract. Although BCa affects both genders, it is more predominant among men. Most of the tumors are non-invasive at diagnosis, however, high rates of recurrence, heterogeneity, and treatment resistance lead to significant mortality. Therefore, it is necessary to identify and understand the role of novel metabolic targets and explore their therapeutic potential against BCa. Rapidly proliferating cancer cells have high nutritional demand which necessitates metabolic reprogramming and reliance on the alternative nutrients in the tumor microenvironment. Based on the human BCa transcriptome data analysis (TCGA data), we identified that the Galactokinase-1 (GALK1) gene is significantly overexpressed (p&amp;lt;0.0001) in human bladder tumors compared to normal tissue, and its expression also correlates with disease stage and poor prognosis. GALK1 is a member of the Leloir pathway that facilitates the initial step of galactose breakdown. Interestingly, we observed abundant expression of GALK1 in various human and rodent BCa cell lines as well as rodent bladder tumor tissues. Hence, we hypothesized that GALK1 may contribute to BCa survival by contributing to the cancer cell proliferation and could serve as a novel target for the management of this malignancy. To understand this, we abrogated GALK1 gene expression in MB49 cells using siRNA and found a significant decrease in cell proliferation with increased apoptosis. Further treatment of various human bladder cancer cells, in vitro with a small-molecule GALK1 inhibitor (Cpd36), resulted in reduced proliferation (IC50 = 29.09 - 43.67μM), migration and invasion potential. A similar growth inhibitory effect was also observed in BCa spheroids and tumoroids. Cell cycle analysis indicated that Cpd36 induced significant G1 arrest (p&amp;lt;0.0001) in BCa cells and pronounced G2/M arrest (p&amp;lt;0.0001). GALK1 inhibition increased mitochondrial ROS production while lowering the mitochondrial membrane potential and triggered apoptosis in BCa cells. GALK1 inhibition induced cell growth arrest was associated with decrease in protein levels of GALK1, PCNA, and Cyclins. Additionally, the induction of apoptosis was associated with increase in cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase (PARP). Further, we investigated the effect of GALK1 abrogation on chemotherapeutic drugs sensitivity. Invitro drug combination data suggested that targeting GALK1 sensitized the BCa cells to cisplatin or gemcitabine as evident from significant reduction in the IC50 of these chemotherapeutic drugs. Based on these findings, GALK1 plays a tumor promoting role in BCa and its inhibition may be a promising therapeutic target for its prevention and treatment. (Funding supported in part by NCI-P30CA225520 and ACS-134128-IRG-19-142-01 grants). Citation Format: Surya P. Singh, Chinthalapally V. Rao, Venkateshwar Madka. Galactokinase 1 is a novel metabolic target against bladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5602.