TGF-β-induced epithelial to mesenchymal transition drives proteoglycan binding specificity of HPV-based drug conjugates for cancer cells.

Background: Human papillomaviruses (HPVs) utilize specifically modified proteoglycans (PGs) within the basement membrane as attachment factors prior to cell entry and infection. Similarly modified PGs are also found on cancer cells, which enables HPV with tumor-selective binding properties and highlights the potential development of HPV capsid-based anti-cancer therapies. In this study, we sought to investigate cancer-specific gene signatures and genetic factors that give rise to selective binding by HPV capsids. Methods: Using belzupacap sarotalocan (bel-sar; AU-011), an HPV virus-like drug conjugate (HPV-VDC) currently in clinical trials, we performed a cell binding screen using 115 cancer cell lines from which we performed gene expressions analysis. We developed drug resistant lines to investigate the developmental factors involved in tumor targeting. Results: We identified a strong association between drug binding and pathways involved in TGF-β-induced epithelial to mesenchymal transition (EMT). Furthermore, dose escalation treatments leading to selection of bel-sar resistant HeLa cells resulted in a marked reduction in TGF-β signaling and reversal of EMT, which was associated with a reduction in the synthesis and expression of heparan- and chondroitin sulfate proteoglycans. Conclusion: Overall, these data suggest that bel-sar binding is strongly dependent on the differential expression and modification of PGs that occurs during the EMT process. As many cancers undergo EMT during progression and invasion, these data provide mechanistic insights underlying the tumor-selective binding ability of HPV-VDCs. (200 words).