Figure 6

Peptides derived from TGFBI mediate NSCLC cells response to chemotherapy and the induction of caspase 8 and caspase 3/7 activation. (A) Western blot detection of proteolytic fragments of TGFBI in H1299 and A549 cells transiently transfected with the TGFBI expression vector. (B) Detection of caspase 3/7 activity in A549 and H1299 cells exposed for 24 h to cell supernatants derived from cultures of A549 and H1299 cells transiently transfected with the TGFBI expression vector. Control: non-treated cells; Control > 3 kDa: NSCLC cells exposed to supernatants from non-transfected cell cultures containing fragments larger than 3 kDa in size; Control < 3 kDa: NSCLC cells exposed to supernatants from non-transfected cell cultures containing fragments smaller than 3 kDa in size; TGFBI > 3 kDa: NSCLC cells exposed to supernatants from TGFBI-transfected cells containing fragments larger than 3 kDa in size; TGFBI < 3 kDa: NSCLC cells exposed to supernatants from TGFBI-transfected cells containing fragments smaller than 3 kDa in size; αvβ3: cells blocked with anti-αvβ3 blocking antibody 1 h before the addition of the supernatant; Et: Cells exposed to IC₅₀ etoposide for 24 h. Statistical analyses were performed using Student t-test to compare caspase 3/7 activity in control cells (** p < 0.01) or etoposide treated cells (## p < 0.01) to the caspase activity in cell cultures treated with supernatants. (C) Caspase 8 and (D) caspase 3/7 detection in A549 and H1299 cells maintained for different time-periods in the presence of TGFBI < 3 kDa supernatant. Statistical analyses were performed using Student t-test and the caspase activity of treated cells was compared to that of untreated cells. (*p < 0.05; **p < 0.01).