Figure 3.

H5.110CMVhIFN-β treatment results in induction of apoptosis in established human colorectal cancer cell line tumors in an athymic nude mouse model for liver metastases. KM12L4 cells were directly injected in the livers of athymic nude mice. On day 14, when tumors were 3–5 mm³, animals were randomized to receive PBS, H5.010CMVβ-gal, or H5.110CMVhIFN-β via tail vein injection. Three animals per group were sacrificed 2, 5, and 9 days after vector administration. The liver tumors were bisected in the horizontal plane and fixed in 10% neutral buffered formalin for 24 hours, then routinely processed, embedded in paraffin, and sectioned at 6 μm. Slides were stained with hematoxylin and eosin in standard fashion. Apoptotic cells were detected using the in situ death detection kit Flourescein (Roche Molecular Biochemicals).