Expression of the human fetal bac h19 gene in invasive cancers.

We have isolated a new -ene, named BAC, which is the human equivalent of the murine H19 gene and is highly expressed in most fetal tissues and in a variety of fresh tumors. BAC was analyzed in 130 untreated invasive carcinomas of different types. The frequency of BAC-expressing cancers as well as the level of expression greatly varied among the different types of cancer and within the same type of cancer. For example, the 2.3 kb BAC transcript band was detected in 94% of breast adenocarcinomas and in only 35% of epidermoid lung carcinomas with differences of 100-fold in the level of expression between tumor specimens. The majority of tumor tissues displayed BAC expression while their normal counterpart did not with the exception of normal breast tissues which contained low but significant level of BAC transcript. It is possible that BAC expression was influenced by the presence of gene deletions in tumors. Indeed, this gene is located in chromosome 11p15, a region in which deletions have frequently been observed in human cancers. Therefore, the variable levels of expression could have a biological significance and be used as a marker of tumor progression.