Numerous murine models are available to study human cancer. These models are used
to investigate the factors involved in malignant transformation, invasion and metastasis,
as well as to examine response to therapy. One of the most widely used models is the
human tumor xenograft. In this model, human tumor cells are transplanted, either under
the skin or into the organ type in which the tumor originated, in immunocompromised
mice that do not reject human cells. For example, the xenograft will be readily accepted
by athymic nude mice, severely compromised immunodeficient (SCID) mice, or other immunocompromised
mice. Depending upon the number of cells injected, or the size of the tumor transplanted,
the tumor will develop over 1–8 weeks (or in some instances 1–4 months, or longer),
and the response to appropriate therapeutic regimes can be studied in vivo. With this approach, using nude mice, we have established a subcutaneous xenograft
and intrathoracic orthotopic models with human non-small cell lung cancer cell line
(NCI-H460). These tumors grow to an appreciable volume within 10 days with 100% frequency
subcutaneously and in the thorax. To test the validity of these models, we treated
mice with known anticancer chemotherapeutic agent (Topotecan). This group showed significant
reduction in the tumor volume compared to the untreated group. In addition, we have
established a liver xenograft using HepG2 liver cell line. Compared to NCI-H460, HepG2
showed 50% frequency to tumors production. In conclusion, these models can be used
to assess the anticancer property of different natural products in vivo.
