C. Jumarie et C. Malo, ALKALINE-PHOSPHATASE AND PEPTIDASE ACTIVITIES IN CACO-2 CELLS - DIFFERENTIAL RESPONSE TO TRIIODOTHYRONINE, In vitro cellular & developmental biology. Animal, 30A(11), 1994, pp. 753-760
Caco-2 cell human colon adenocarcinoma cell line was used to study the
hormonal regulation of small intestinal epithelial cell differentiati
on. We had previously shown that insulin-transferrin-selenium and trii
odothyronine (5 X 10(-8) M)-supplemented medium can best replace serum
after 2 days of culture for both the maintenance and differentiation
of Caco-2 cells. The present study demonstrates that precoating petri
dishes with complete serum allows the growth and differentiation of Ca
co-2 cells seeded directly in serum-free medium. On the other hand, pr
ecoating with dialyzed serum inhibits alkaline phosphatase and dipepti
dyl-dipeptidase IV activities by more than 50%. The results obtained w
ith complete serum-precoatad culture plates indicate that there is no
synergy between insulin and triiodothyronine because cells maintained
in transferrin-selenium and triiodothyronine-supplemented medium, with
or without insulin, express comparable enzyme activities. Moreover, l
arge increases in alkaline phosphatase and dipeptidyl-dipeptidase IV a
ctivities were observed when triiodothyronine was added to the culture
medium by the time confluency was reached. In contrast, gamma-glutamy
ltransferase was lowered to a greater extent when triiodothyronine was
present from the beginning of culture. These findings show that triio
dothyronine preferentially stimulates alkaline phosphatase and dipepti
dyl-dipeptidase IV activities during the differentiation period wherea
s it selectively inhibits gamma-glutamyltransferase during the prolife
ration phase. Triiodothyronine acts in a dose-dependent manner.