FIGURE 4.
SIDT1 deficiency abrogates chemoresistance induced by a minority miR-21-expressing subpopulation of pancreatic adenocarcinoma cells. Chemoresistance was quantified by MTT assay, and IC50 values were derived. a, the IC50 of gemcitabine was significantly increased by direct coculture of doxycycline-activated BxPC3miR21 with BxPC3CkmiR21 cells (ratio 1:100). b, the alteration in IC50 was minimal when the minority subpopulation was indirectly cocultured (Transwell). The gemcitabine IC50 was unaffected by coculture of BxPC3miRN/S with BxPC3CkmiR21. Means ± S.D. (error bars) are presented (n = 3). c, the increase in IC50 induced by miR-21 was attenuated when cells were treated with SIDT1–3′-UTR siRNA 1 but not by control mismatch siRNA. SIDT1 rescue abrogated the effect of SIDT1–3′-UTR siRNA 1. d, gap junction inhibition using 25 μm AGA did not significantly affect the increase in IC50 induced by miR-21.