Targeting non-junctional Claudin-1 with monoclonal antibodies to treat hepatocellular carcinoma [scRNA-seq]

Abstract: Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide. Despite new treatment approvals, treatment response and prognosis of patients with advanced HCC remains poor. Claudin-1 (CLDN1) is a membrane protein expressed in tight junctions but also non-junctionally at the basolateral membrane of hepatocytes. While the function of CLDN1 within tight junctions is well characterized, the role of non-junctional (NJ) CLDN1 in HCC remains unexplored. Here we show that targeting NJ-CLDN1 with a humanized monoclonal antibody (mAb) suppresses tumor growth in different pre-clinical models. Mechanistic studies including single cell RNA sequencing of multicellular patient tumorspheres suggest that non-junctional CLDN1 regulates tumor stemness, metabolism and oncogenic signaling with impact on the tumor immune microenvironment. Our results provide the rationale for targeting NJ-CLDN1 in HCC and pave the way to novel therapeutic interventions with NJ-CLDN1 mAbs aimed at improving the limited efficacy of current therapies. To investigate the molecular effects of CLDN1 mAb on HCC tumor cells and its tumor microenvironment, multicellular spheroids were generated from tumorous HCC tissue and treated with CLDN1 mAb or Control mAb for 24 hours. Spheroids were then dissociated into single cells and sorted for scRNAseq in an unbiased way.