Abstract 57: Membrane-bound heat shock protein Hsp70 as a new target in oncology: from theory to practice

Abstract Heat shock proteins (HSP), particularly 70 kDa heat shock protein (Hsp70), apart from their cytoplasmic localization in cancer cells, can be exposed on the surface of the plasma membrane. We report that the membrane-bound protein mHsp70 of malignant brain tumors is required for high migratory and invasive activity of cancer cells. Live-cell inverted confocal microscopy of adult and pediatric brain tumor samples (n=32) showed mHsp70 overexpression on the membrane, especially in the perifocal zone. Mass-spectrometry analysis of lipid rafts isolated from brain tumor cells confirmed the presence of the protein in HSP cluster (including representatives of other families such as HSP70, HSP90), which in turn, during interactome analysis, was associated with proteins involved in cell migration and invasion (i.e., Rac1, RhoC, myosin-9). Application of small-molecule inhibitors of HSP70 (JG-98, PES) led to a significant decrease in the invasive potential of cells isolated from a tumor sample of patients, which indicates the role of the chaperone in invasion. Moreover, the use of chaperone inhibitors in orthotopic brain tumors model in rodents significantly decreased tumor progression, which was accompanied by an increased overall survival. Data demonstrate that chaperone inhibitors, particularly JG-98, disrupt the function of mHsp70, thereby providing an opportunity to better understand the diverse functions of this protein and offer aid in the development of novel cancer therapies. Apart from chaperone inhibitors we developed mHsp70-targeted peptide that could efficiently cross the blood-brain barrier accumulating in the glioblastoma cells in vivo. Subsequently, in the orthotopic GL261 mice and C6 rat glioma, intravenous administration of the fluorescently labeled peptide resulted in the tumor retention of agent (further confirmed by histological studies) 24 hours following i.v. injection. Topical application of the mHsp70-targeted peptide (sprayed over the freshly dissected brain tissues) helped to delineate the tumors in glioma-bearing animals employing intraoperative fluorescent imaging system. In conclusion, peptide recognizing mHsp70 demonstrated high targeting properties which could be employed for the intraoperative visualization as well as for developing of a potential carrier for drug delivery. Citation Format: Maxim Shevtsov, Natalia Yudintceva, Danila Bobkov, Ruslana Likhomanova, Anastasiya Nechaeva, Anastasiya Lukacheva, Natalia Mikhailova, Viacheslav Fedorov, Elena Oganesyan, Oleg Rozanov, Konstantin Samochernykh, Alexey Ulitin, Alexander Kim, Elena Mikhailova, Rustam Ziganshin, Emil Pitkin, Stephanie E. Combs. Membrane-bound heat shock protein Hsp70 as a new target in oncology: from theory to practice [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 57