The free cytoplasmic calcium concentration of tumorigenic and non-tumorigenic human somatic cell hybrids

Abstract

Summary The fluorescent indicator of Ca2 + concentration, quin-2, has been used to measure the concentration of free Ca2 + in the cytoplasm of tumorigenic and non-tumorigenic human somatic cell hybrids. The cell hybrids were derived from the fusion of a HeLa derivative (D98 AH2) and normal human fibroblasts. The calcium concentration of the tumorigenic cell lines was 180+7nM and the level in the nontumorigenic cells was 136+6nM. This difference was statistically highly significant (P<0.001). Control experiments are reported which show that the level of 3a2+ measured is not influenced by cell density or by the concentration of quin-2-tetra-(acetoxymethyl)ester used in these experiments. The possible implications of this elevated level of cytoplasmic calcium in tumorigenic cells are discussed.

Intracellular distribution of calcium and zinc in normal, hyperplastic, and neoplastic human prostate: X‐ray microanalysis of freeze‐dried cryosections

“…We have earlier reported a tendency toward age-related elevation of intracellular calcium in hyperplastic prostates [ 161. Evidence suggests that calcium ions have an important role in the triggering of mitogen-induced cell proliferation in a number of cell types [34,35], and some cancer cells contain elevated calcium levels [36,37]. However, a role for calcium in growth disturbances in the prostate remains speculative.…”

Vasoactive intestinal peptide increases intracellular free calcium in rat and human pituitary tumour cells in vitro

“…Cells grown on cover-slips were washed six times and fitted in an adapted cuvette which held the coverslip at the top and bottom in a central position (Banyard & Tellam, 1985). To achieve rapid mixing of test substances 1 ml medium was withdrawn into a pipette already containing the substances to be added and quickly returned to the cuvette.…”

“…For attached cells, the autofluorescence of unloaded cells was first measured and the maximum fluorescence of the Quin-2-loaded cells was later found by the addition of a lower concen¬ tration of digitonin (5 mmol/1) to allow a gradual entry of calcium without loss of indicator or cells, as described by Banyard & Tellam (1985). Minimum fluorescence could then be calculated (Moolenaar, Tertoolen & de Laat, 1984).…”

Ca2+ and calmodulin are involved in the processes conferring stability to DNA in proliferating neoplastic cells

“…Non-malignant cells as well as growth-arrested malignant cells do not show fragmentation of DNA. This may he correlated to the finding that there are increased concentrations of free Ca2+ in malignant as compared to non-malignant cells (Banyard and Tellam, 1985). There is also a 2to 4-fold increase in the amount of calmodulin in transformed versus normal cells as well as in dividing as compared with nondividing cells.…”