Abstract 5047: Exosomes derived from HIV-1-infected T cells activate ERK 1/2 through EGFR and TLR3 in cancer cells

Abstract

Abstract Exosomes secreted from HIV-1-infected T cells play important roles in coordinating the immune responses and disease processes in HIV-infected people who are treated with antiretroviral therapy. We hypothesize that exosomes from HIV-infected T cells can promote growth and progression of non-AIDS-defining cancer cells. Activation of the MAPK ERK 1/2 is important for cancer cell survival, proliferation and invasion. We investigated the ability of exosomes from HIV-1-infected T cells to activate ERK 1/2 in head neck squamous cell carcinoma (HNSCC) and lung cancer cells for cancer cell proliferation and progression. Exosomes were isolated from Jurkat and J1.1, a latently HIV-1-infected Jurkat cells, using differential ultracentrifugation and quantified by acetylcholinesterase (AchE) activity. HNSCC cell line HSC3 and lung cancer cell lines NCI-H1299 and NCI-H1437 cells were treated with exosomes. To test the involvement of EGFR and TLR3 in ERK 1/2 activation by exosomes, EGFR neutralizing antibody Cetuximab or the TLR3/dsRNA inhibitor complex was added to cancer cells 30 min prior to adding exosomes. To test the entry of exosomes into cells, HEK293 cells were transiently transfected with EGFR-GFP, and seeded into glass bottom 35 mm dishes, time lapse Z-stacking imaging was performed and deconvolution was used to remove out of focus signals. By using Western blotting, we found that exosomes from J1.1 cells (HIV-1-infected), but not those from HIV-negative Jurkat cells, constantly induced ERK 1/2 phosphorylation in HNSCC and lung cancer cells. Cetuximab dramatically decreased ERK activation by exosomes from J1.1 cells, suggesting an EGFR-dependent ERK activation. While EGF induced a whole series of EGFR phosphorylation, exosomes from J1.1 cells failed to do so, suggesting that exosomes from J1.1 cells trigger ERK activation through a non-canonical EGFR pathway. Furthermore, ERK activation was significantly reduced in TLR3/dsRNA inhibitor pretreated cancer cells in response to exosomes from J1.1 cells, indicating exosomes triggered ERK activation is also TLR3 dependent. Time lapse imaging showed that exosomes quickly entered into cells within two minutes; however, Cetuximab greatly delayed exosome entry. To conclude, we found that exosomes from HIV-infected T cells can induce ERK activation in HNSCC and lung cancer cells through interaction with EGFR and TLR3. Citation Format: Zhimin Feng, Lechuang Chen, Hong Yue, Bingcheng Wang, Ge Jin. Exosomes derived from HIV-1-infected T cells activate ERK 1/2 through EGFR and TLR3 in cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5047.