FIGURE 2.
In vivo effect of abrogation of the Fhit-Fdxr interaction. Human colon cancer cells, HCT116 FDXR+/+/+, and FDXR+/-/- (1 × 106) cells were injected into the flanks of nude mice subcutaneously, and siFHIT or nonspecific sequence (siNSR) oligonucleotides with Lipofectamine were injected into the tumors on days 7 and 14. Mice were sacrificed on day 21 and tumor volumes calculated. A and B, FDXR+/-/- tumors treated with siFHIT were significantly smaller than tumors of other groups (scale bar, 10 mm). A, time course of tumor growth in all groups. B, tumors were excised on day 21, and portions of each tumor were taken for fixation, processing, and immunohistochemical analyses. C, tissue sections of siFHIT-treated tumors were stained for Fhit and Fdxr expression; representative results are shown; staining for apoptotic cells (by ISOL method) is also shown on the right. Expression of Fhit was low in both si-FHIT-treated tissues (panels a and d); expression of Fdxr was low in the tissue from FDXR+/-/- tumor (panel b) and high in tissue from FDXR+/+/+ tumor (panel e). Many apoptotic cells with black-brown nuclei were observed in tissue from FDXR+/-/- tumor (panel c) but not in tissue from FDXR+/+/+ tumor (panel f) panels a, b, d, and e, ×200; panels c and f, ×400. Similarly stained tissue sections of si-NSR treated tumors are shown below the si-FHIT-treated sections.