Growth condition-dependent synchronized changes in transcript levels of type II hexokinase and type 1 glucose transporter in tumor cells

Transcript levels of hexokinase (HK) isozymes and glucose transporter (GLUT ) isoforms in RNA samples of AH130 cells obtained from dish cultures and as cites were evaluated in a quantitative manner. In AH130 cells cultured in d ishes, HKI and HKII were expressed at a similar level, but HKIII and HKIV w ere not. GLUT1 and GLUT3 were also expressed, and messages of these two iso forms represented 27% and 71%, respectively, of the total GLUT messages. A faint signal of GLUT2 was also observed. On the contrary, in cells grown as ascites, the transcript of HKII was dominant, and its level was about 15-f old over that of dish-cultured AH130 cells. Transcript levels of GLUT1 and GLUT3 were 4.5- and 2-fold, respectively, higher than those in dish-culture d cells. Thus, GLUT1 was more susceptible to changes in culture conditions than GLUT3. Based on these results, we concluded that the change in growth conditions caused synchronized changes in the transcript levels of HKII and GLUT1 in AH130 cells. However, such marked changes in the transcript level s of HKII and GLUT1 were not observed when AH130 cells were cultured in dis hes under a hypoxic condition, indicating that the observed changes were no t solely attributable to the difference in oxygen concentration between the ascites and cell culture conditions. Accordingly, other factors such as gr owth factors may be responsible for this difference in levels of HKII and G LUT1 between the two growth conditions. (C) 2001 Elsevier Science B.V. All rights reserved.