Use of clinically relevant human-scid-mouse models in metastasis research

Cell differentiation and chemotherapy influence p53 and Mdm2 immunoreactivity in human HT29 colon cancer cells grown in scid mice

Absence of a functional p53 gene product can lead to increased p53 accumulation in cancer cells. In this contribution, the association between cell differentiation, chemotherapy and p53 immunoreactivity in human HT29 colon cancer cells grown in scid mice as undifferentiated cells and as mucin containing signet-ring cells was investigated. Mutated p53 was more frequently expressed in the undifferentiated tumour cells than in the signet-ring cells. 5-fluorouracil (5FU) treatment resulted in a substantial increase in the p53-positive signet-ring cell population (from 17% to 45%) and in an increased Mdm2 immunoreactivity. These findings indicate that mutated p53 expression is related to the differentiation pattern and that tumour cells devoid of mutated p53 immunoreactivity are preferentially eliminated by 5FU treatment.

Immunohistochemical detection of the MUC1 gene product in human cancers grown in scid mice

Alterations in mucin expression have been detected in many clinically relevant cancers and, in particular, the polymorphic epithelial mucin, encoded by the MUC1 gene, has attracted considerable attention. We investigated its expression in human breast, colon, ovarian, lung, and skin cancer cells and their metastases grown in severe combined immunodeficient (scid) mice using three different monoclonal antibodies (HMFG-1, HMFG-2, and SM3). Four of five breast cancer cell lines, three of five colon cancer cell lines, two of three small-cell carcinoma of the lung cell lines, and A 431 cells all expressed the MUC1 gene product. Neuraminidase predigestion often enhanced HMFG-1 immunoreactivity, which was more widespread and stronger than SM3 immunoreactivity. A considerable heterogeneity of MUC1 gene product expression was observed in the same tumors grown in different mice. The binding pattern between single-cell/small-cell clusters (up to 10 cells) and larger cell number aggregates varied. The results indicate that the MUC1 gene expression both in primary tumors and metastases is not tightly controlled within a particular tumor cell line. Because of this heterogeneous antigen expression in vivo, it appears impossible to target all metastatic deposits by a single monoclonal antibody directed against the MUC1 gene product. (J Histochem Cytochem 46:127-134, 1998)