Minimal Xenograft Tumor Growth Variability in Nude Mice Infected with Corynebacterium bovis as a Single Pathogenic Agent

Reduced xenograft engraftment and delayed tumor growth in immunocompromised mice have been associated with infection by Corynebacterium bovis, a highly contagious bacterium that causes sporadic clinical disease and chronic shedding. To learn what effect C. bovis infection may have on the reproducibility of preclinical cancer studies, subcutaneous tumors were monitored in male and female nude ( Foxn1 nu ) mice topically infected with C. bovis 2 to 3 weeks prior to cell injection (chronically infected) or at the time of cell injection (acutely infected) and compared with tumors in uninfected control mice. There were largely no significant differences in tumor engraftment rates, final tumor weights, or final tumor volumes between infection groups for any of the 3 established human cell lines; that is, SJSA-1, an osteosarcoma; HT-29, a colorectal adenocarcinoma; and A549, a lung carcinoma. However, HT-29–engrafted tumors grew significantly more slowly in acutely infected males than in the chronically infected or uninfected males, although no difference was present between the HT-29–engrafted female groups. No epidermal hyperplasia or hyperkeratosis was present in either of the infected groups, compared with the controls, which paralleled the absence of scaly skin clinically across all groups. In summary, our results suggest that C. bovis as a single pathogenic agent may have a limited effect on xenograft engraftment and growth. Investigators using different strains of immunocompromised mice, different cell lines, or mice housed in facilities with different health status from that described in the present study but endemic for C. bovis should perform pilot studies to determine whether tumor engraftment and/or growth is affected by infection.