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ß-Hexosaminidase Isoenzymes in Tissues, Cultured Cells, and Media from Human Fetal Intestine and Colonic Adenocarcinoma¹

Gastrointestinal Research Laboratory, Veteran's Administration Hospital, and University of California, San Francisco, California 94121

Isoelectric focusing of tissue homogenates revealed a predominance of ß-hexosaminidase B in colonic adenocarcinoma, whereas ß-hexosaminidase A was greater in paired normal-appearing colonic mucosa from the same patients as well as in a specimen of human fetal colonic mucosa. Because of the recognized cellular heterogeneity of these tissues, our studies were extended to an examination of these isoenzymes in 20 cultured epithelial cell lines derived from human fetal intestine and colonic carcinoma as well as the secreted enzymes in their culture media. While the B:A isoenzyme ratio was higher in human cancer cells as compared to fetal cells, some of the cancer cell lines had a greater proportion of the A isoenzyme. Examination of the isoenzyme profiles in the media of these cells revealed a greater B:A ratio whether of fetal or cancer cell origin. These studies parallel the apparent biological differences of neoplastic colonic epithelium occurring in vivo and are reminiscent of reported oncodevelopmental changes in enzymatic properties present in some malignant tissues. The differential stabilities of these two isoenzymes derived from the culture media of both types of cell lines in vitro may limit their value as markers of human colonic neoplasia.

¹ Supported by USPHS Grant CA-14905 from the National Cancer Institute, through the National Large Bowel Cancer Project, and by a Veteran's Administration Research Grant.

² Recipient of a fellowship from the Medical Research Council of Canada, Ottawa, Ontario, Canada. Present address: U. B. C. Cancer Research Center, 601 West 10th Avenue, Vancouver, British Columbia, Canada.

³ To whom requests for reprints should be addressed.

Received 2/26/79. Accepted 5/24/79.