p53 expression, growth, and spontaneous metastasis of the human GI 101 breast carcinoma in athymic nude mice

Anti-cancer effects of F16: A novel vascular endothelial growth factor receptor-specific inhibitor

Vascular endothelial growth factor receptor-2 is a dynamic target for therapeutic intervention in various types of cancers. This study was aimed to explore the anti-angiogenic activity of a novel vascular endothelial growth factor receptor-specific inhibitor named F16 in both in vitro and in vivo experimental models. This compound effectively reduced cell proliferation, tube formation, and migration of human umbilical vein endothelial cells in a concentration-dependent manner by directly inhibiting vascular endothelial growth factor binding and subsequent vascular endothelial growth factor receptor-2 phosphorylation. The F16 was also able to inhibit the phosphoinositide 3-kinase/protein kinase B-mediated survival and migration pathways in cancer in addition to inhibiting the focal adhesion kinase and mitogen-activated protein kinases-mediated signaling in GI-101A cancer cells. The chorioallantoic membrane assay followed by tumor growth inhibition measurements with GI-101A breast cancer xenograft implanted athymic nude mice confirmed the in vivo tumor reductive effects of F16. It was interesting to observe a decrease in tumor burden after F16 treatment which correlated very well with the decrease in the plasma levels of mucin-1 (MUC-1). Our studies so far have confirmed that F16 is a specific inhibitor of angiogenesis in both in vitro and in vivo models. The F16 also works very efficiently with Taxol in combination by limiting the tumor growth that is better than the monotherapy with any one of the drugs that were tested individually. Thus, F16 offers a promising anti-proliferative and anti-angiogenic effects with better specificity than some of the existing multi-kinase inhibitors.

A novel orthotopic and metastatic mouse model of breast cancer in human mammary microenvironment

The studies of breast cancer heavily rely on the availability of experimental animal models. An ideal model of breast cancer is not only required to mimic the whole processes of tumor progress and metastasis, but also required to provide a normal human mammary microenvironment for the breast cancer cells to proliferate and metastasize. Numerous mouse models have been introduced in the literature but failed to achieve the two requirements simultaneously. In this study, we developed a novel human breast tissue-derived orthotopic and metastatic (BOM) mouse model of breast cancer, in which the normal human breast tissues were implanted subcutaneously to create a normal human mammary microenvironment, after which the human breast cancer cells were inoculated into the implants. The BOM model not only mimicked the whole processes of tumor progress and metastasis, but also allowed the orthotopic human breast cancer cells to proliferate in the normal human mammary microenvironment, and finally metastasize preferentially to the distant human tissues. Consequently, the BOM model contributed to the orthotopic tumor formation of 100% (11/11) and the metastatic tumor formation of 72.7% (8/11).

From genetic abnormality to metastases: murine models of breast cancer and their use in the development of anticancer therapies

Numerous mouse models of mammary cancer have been developed that mimic selective aspects of human disease. The use of these models has enabled preclinical chemotherapeutic, chemoprevention, and genetic therapy studies in vivo, the testing of gene delivery systems, and the identification of tumour and metastasis suppressor and inducer genes. This review has discussed the most abundantly used murine models of mammary cancer including: spontaneous tumours, chemically induced tumours, orthotopic and syngeneic tumour transplantation, injected tumours, and genetically engineered mice with a predisposition to neoplasia. Each model has been discussed with regards to its merits and limitations for investigating the genetic and phenotypic alterations involved in the human disease as well as its potential usefulness for the development of new treatment strategies. To date no single mouse model is available with the ability to replicate the entire disease process, however, existing models continue to provide invaluable insights into breast cancer induction and progression that would be impossible to obtain using in vitro models alone.

Biological significance of isolated tumor cells and micrometastasis in lymph nodes evaluated using a green fluorescent protein-tagged human gastric cancer cell line

PURPOSE

The biological significance of isolated tumor cells and micrometastasis in lymph node defined by the International Union against Cancer remains essentially unknown because of the lack of appropriate animal models. In the present study, we developed a lymph node micrometastasis model featuring a human gastric cancer cell line tagged with green fluorescent protein gene (GCIY-EGFP), which allows visualization of even isolated tumor cells in the development of metastasis without histologic procedure. Using this model, we investigated the effect of surgery and chemotherapy on the growth of early-phase metastasis formation in the lymph nodes.

EXPERIMENTAL DESIGN

The time course of spontaneous inguinal lymph node metastasis after s.c. inoculation of GCIY-EGFP cells into nude mice was examined with fluorescence dissecting microscopy. Then, the effects of surgical removal of the primary tumor with or without anti-asialo GM1 treatment or postoperative chemotherapy on the growth of isolated tumor cells and micrometastasis in the lymph nodes were examined.

RESULTS

GCIY-EGFP cells were found to metastasize spontaneously to the inguinal lymph nodes to form isolated tumor cells, micrometastasis, and, finally, develop macroscopic metastasis at 1 to 2, 3 to 5, and 5 weeks postinjection, respectively. When the primary tumors were removed within 2 weeks of inoculation, isolated tumor cells, but not micrometastasis, in the lymph nodes regressed by 4 weeks after surgery in all the mice examined (five of five). This spontaneous regression of isolated tumor cells was completely reversed by anti-asialo GM1 treatment, which could deplete natural killer cells effectively in nude mice. Chemotherapy following resection of the primary tumor at an early stage partially eliminated the remaining micrometastasis in the lymph nodes.

CONCLUSIONS

These results suggest that isolated tumor cells in the regional lymph nodes regressed by removal of the primary tumor mainly via natural killer cell-mediated antitumor activity and that micrometastasis in the lymph nodes could be effectively eliminated by the postoperative chemotherapy.