title: Ras oncoproteins transfer from melanoma cells to T cells and modulate their effector functions.
abstract: Lymphocytes establish dynamic cell-cell interactions with the cells they scan. Previous studies show that upon cell contact, various membrane-associated proteins, such as Ras-family proteins, transfer from B to T and NK lymphocytes. Mutations in RAS genes that encode constitutively active, GTP-bound, oncoproteins are rather common in human cancers; for instance, melanoma. Cancer immunoediting has been postulated to contribute to the elimination of malignant melanoma. Thus, we asked whether Ras oncoproteins can transfer from melanoma to T cells, including tumor-infiltrating lymphocytes (TILs), and subsequently induce functional effects in the adopting T cells. To explore this issue, we genetically engineered an HLA-A2(+) melanoma cell line, MEL526, to express GFP or GFP-tagged H-Ras mutants stably. In this study, we show by an in vitro coculture system that GFP-tagged H-Ras, but not GFP, transfers from MEL526 to T cells and localizes to the inner aspect of their plasma membrane. This cell-contact-dependent process was increased by TCR stimulation and did not require strict Ag specificity. Importantly, we found a positive correlation between the levels of the acquired constitutively active H-RasG12V and ERK1/2 phosphorylation within the adopting TILs. We also show a significant increase in IFN-γ production and cytotoxic activity in TILs that acquired H-RasG12V compared to TILs that acquired a different H-Ras mutant. In conclusion, our findings demonstrate a hitherto unknown phenomenon of intercellular transfer of Ras oncoproteins from melanoma to TILs that consequently augments their effector functions.
authors.affiliation: Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Tel Aviv, Israel.
authors.forename: Helly
authors.initials: H
authors.lastname: Vernitsky
authors.forename: Oded
authors.initials: O
authors.lastname: Rechavi
authors.forename: Nir
authors.initials: N
authors.lastname: Rainy
authors.forename: Michal J
authors.initials: MJ
authors.lastname: Besser
authors.forename: Meital
authors.initials: M
authors.lastname: Nagar
authors.forename: Jacob
authors.initials: J
authors.lastname: Schachter
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Lerenthal
authors.forename: Marcelo
authors.initials: M
authors.lastname: Ehrlich
authors.forename: Yoel
authors.initials: Y
authors.lastname: Kloog
authors.forename: Itamar
authors.initials: I
authors.lastname: Goldstein
mesh_terms: D002460:Cell Line; D018920:Coculture Techniques; D006801:Humans; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D008545:Melanoma / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D061251:Primary Cell Culture; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D016283:Proto-Oncogene Proteins p21(ras)