IHC markers of proliferation in HCT-116 and DiFi human CRC xenografts.

<p>Representative high power microscopic images (40x) of HCT-116 and DiFi xenograft tissue stained for Ki67, PCNA, and TK1 are shown along with quantification of the percentage of positive cells per field for each marker. HCT-116 and DiFi xenograft tissues exhibit a similar proportion of proliferating cells as measured by Ki67 indices (68.50 ± 5.52 % vs. 72.37 ± 12.64%; p = 0.0651). The proportion of PCNA positive cells, representing S-phase, was significantly increased in HCT-116 xenografts (53.91 ± 3.18 %) compared to DiFi xenografts (13.59 ±1.48%; p = 0.0007). Similar to PCNA, the percentage of TK1-positive cells was significantly higher in HCT-116 xenografts (38.32 ± 1.90 %) than DiFi cells (17.95 ± 3.95 %; p = 0.0007). TK1 indices for both cell lines were reduced compared to Ki67 indices.