Identification of genes that are expressed in a
cancer cell-specific manner can provide markers for detection, diagnosis, and
disease progression. We have previously reported that
receptor tyrosine kinase ligands in concert with
ligation of
alphavbeta5 integrin induce expression of Mig-7 restricted to
carcinoma cells. Because of this highly specific expression, we hypothesized that Mig-7 could be used as a marker of occult
tumor cells. The objective of this study was to begin to test this hypothesis by generating Mig-7 specific
antisera and RT-PCR methods for detection of Mig-7 expression in tissues and blood from
cancer patients as compared to those from normal subjects. By immunohistochemistry and by RT-PCR, we detected Mig-7
mRNA in lymph nodes from 7 out of 9 (77.8%)
endometrial carcinoma xenograft mice but not from any of the 5 negative control animals. Mig-7 expression was more specific than Met expression, the RTK that binds
Scatter factor and is used as a marker of poor progression, in
endometrial carcinoma as compared to normal endometrial tissue samples. In 87.3% of
tumors from various tissues including breast, lung, colon and ovary, we detected Mig-7 expression. Blood samples from untreated metastatic
cancer patients also displayed Mig-7
mRNA in contrast to a lack of expression in
chemotherapy treated or normal individuals. In conclusion, we report the first immunohistochemical and RT-PCR assays for Mig-7 and discuss its highly specific localization to
cancer cells in contrast to an absence in normal cells. Our preliminary data indicate that Mig-7 may be a potential early marker of migrating and circulating
carcinoma cells.