Fig. 3

miR-340-5p is essential for the hypoxic EV-induced radioresistance shift in OSCC. a The miR-340-5p level was greatly elevated in H-EV-treated OSCC cells but not in N-EV-treated OSCC cells. b qRT-PCR revealed miR-340-5p expression in OSCC cells after coculture with RNase A-treated EVs. c miR-340-5p levels in OSCC cells treated with RNase A or with RNase A and Triton X-100 together, as detected by qRT-PCR assays. d-e The expression of miR-340-5p in OSCC cells was associated with H-EV supplementation in a time-dependent (d) and dose-dependent (e) manner. f qRT-PCR confirmed the effect of miR-340-5p knockdown in OSCC cells. g No significant changes were observed by qRT-PCR between OSCC cells cocultured with PBS or H-sh-miR-340-5p-EVs. h-i Knockdown of miR-340-5p in hypoxic EVs rescued the suppression of IR-induced apoptosis caused by H-EVs. j Knockdown of miR-340-5p in hypoxic EVs reversed the H-EV-induced decrease in γ-H2AX expression after irradiation in OSCC cells (scale bar = 20 μm). k-l Knockdown of miR-340-5p in hypoxic EVs reversed the decreased in TUNEL-positive cell numbers in OSCC xenografts after irradiation. m Alterations in the tumour volume in each group (n = 6). n Images of tumours in each group (n = 6). NC: cells transfected with negative control lentiviral vectors