LDH isoenzymes in cell cultures from transplantable hamster tumors with dissimilar histogenesis and differentiation.

LDH isoenzymes were assayed by acrylamide disc electrophoresis in the following material: (a) cells from 4 transplantable hamster tumors; (b) cells from the same tumors cultured for 0, 4, 12 or 24 h as well as for 3, 7, 12 or 26 days; (c) tumors obtained after re-inoculation of cells cultured for 26 days. During the first days of culture, the cells retained LDH patterns similar to those of tumors in vivo. Then a progressive increase in the M/H ratio was observed in all cultures. This was followed by a complete disappearance of LDH 1,2,3. In the tumors appearing after re-inoculation of cultured cells, re-emergence of the patterns seen in the original tumors was noted. The mechanism of the observed changes remains hypothetical although an adaptive re-arrangement of gene activity controlling the production of M and H subunits and/or in vitro selection of clones with higher M/H ratio is postulated.