Journal Article

Plasma membrane calcium ATPase 4 and the remodeling of calcium homeostasis in human colon cancer cells

Cho S. Aung, Weilan Ye, Greg Plowman, Amelia A. Peters, Gregory R. Monteith and Sarah J. Roberts-Thomson

in Carcinogenesis

Volume 30, issue 11, pages 1962-1969
Published in print November 2009 | ISSN: 0143-3334
Published online September 2009 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/bgp223
Plasma membrane calcium ATPase 4 and the remodeling of calcium homeostasis in human colon cancer cells

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A remodeling of calcium homeostasis has been identified as a characterizing feature of some cancers. Possible consequences of this include alterations in many pivotal physiological responses including apoptosis, proliferation and gene transcription. An alteration in calcium homeostasis can occur via changes in the expression of proteins that transport calcium and examples of cancers where this is seen includes the prostate and breast. A specific isoform of the calcium efflux pump, plasma membrane Ca2+-ATPase (PMCA) 4, is significantly upregulated during differentiation of the HT-29 colon cancer cell line suggesting that it may also be altered in colon cancer. We now report that differentiated HT-29 colon cancer cells have pronounced plasma membrane PMCA4 localization, consistent with augmented calcium efflux. Assessment of PMCA4 transcription in human colon cancer samples suggests that PMCA4 is significantly (P < 0.000001) downregulated early in the progression of some colon cancers as these cells become less differentiated. Inhibition of PMCA4 using small interfering RNA did not induce cell death or augment sensitivity to the mitochondrial uncoupler carbonyl cyanide 3-chlorophenylhydrazone (CCCP) or tumor necrosis factor-related apoptosis-inducing ligand. Reversing the colon cancer remodeling of PMCA4 by overexpression reduced cellular proliferation (P < 0.01) and downregulated transcription of the calcium sensitive early response gene FOS. Our studies suggest that the remodeling of the calcium signal in colon cancer is associated with compromised calcium efflux at a level that promotes proliferative pathways while avoiding increased sensitivity to apoptotic stimuli.

Journal Article.  5783 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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