Intracellular levels of calmodulin are increased in transformed cells

Abstract

By using Hoechst 33342, rabbit anti calmodulin antibody,FITC-labeled goat anti rabbit IgG and SR101(sulfo rhodamine 101)simultaneously to stain individual normal and transformed cells, the microspectrophotometric analysis demonstrated that 3 markers which represented the nucleus , calmodulin and total protein respectively, could be recognized in individualj cells without interference. The phase of the cell cycle was determined by DNA content (Hoechst 33342). We found that in transformed cells (NIH3T3) tsRSV-LA90,cultured at 33℃ and transformed C3H10T1/ 2 cells), the ratio of calmodulin to total protein (based on the phases of cell cycle)was higher than that in normal cells (NIH3T3 tsRSV−LA90 cells, cultured at 39℃ and C3H10T1/2 cells)in every cell cycle phase. This ratio increased obviously only from G1 to S phase in either normal or transformed cells. The results showed that calmodulin really increased during the transformation, and its increase was specific. In the meantime when cells proceeded from G1 to S, the intracellular calmodulin content also increased specifically.

Advances in Intracellular Calcium Signaling Reveal Untapped Targets for Cancer Therapy

“…It is a common observation for tumor cells to express higher levels of CaM which complements the raised levels of cytosolic Ca 2+ ions relative to benign tissues [ 356 , 357 , 358 , 359 , 360 ]. Although it was contended that this observation was cell type-, culture condition-, or transformation agent-specific, Wang et al (1992) confirmed a significant increase in CaM levels at the individual cell level between transformed and normal cells during G1 to S phase transition [ 361 ]. It was further validated that the surge in CaM levels was specific to cellular transformation and not due to a rise in total intracellular protein during cell cycle progression.…”