I was wondering if HeLa S3 cells have any known mutations in the PI3 kinase pathway which would make them an unsuitable cell line for studying PI3 kinase signalling?
Hela cells are well adapted to cadmium which plays a very important role in cell signalling and itself can cause mutations by interfering with DNA repair and also by epigenetic mechanisms can turn off and turn on genes. If you do an analysis of gene expression and find the stress response genes turned on and the housekeeping genes turned off the cell has free cadmium mediating those effects. Cadmium is a globallly dispersed element that is the biochemical link between stressors and the very complex array of effects due to genetic difference, age, nutritional status, and co -exposure to any or all of the other stressors. Successful adaptation produces resiliency and hardiness.
The Sanger Cosmic database lists mutations identified in commonly used cells including HeLa. (also the NCI-60 lines). The HeLa information is here: http://cancer.sanger.ac.uk/cosmic/sample/overview?id=687509 and suggests that there are no reported mutations in core PI3K signaling in this line but there is a mutation in STK11/LKB1(1). LKB1 is a tumor suppressor and is a regulator of AMPK which feeds into the PI3K pathway at moor. As far as I can tell, no core PI3K associated genes have been specifically sequenced (e.g. PTEN, pPI3KCA, PKB/Akt, etc.) so there may be some changes (plus epigenetic silencing is not detected in this database). The best way to determine whether the cells have normal PI3K signaling is to serum starve for at least an hour and then measure phospho-AKT 273 (use a PI3K agonist as a positive control). If the pathway is functionally active, there ail be a strong signal in the absence of agonist. HeLa cells are difficult to quiesce though so there will likely be some signalling - this also makes these cells less than ideal for evaluating signalling. Notably, HEK293 cells are mutant in the PI3K signaling pathway.
(1) Wingo SN, Gallardo TD, Akbay EA, Liang MC, Contreras CM, Boren T, Shimamura T, Miller DS, Sharpless NE, Bardeesy N, et al. 2009. Somatic LKB1 mutations promote cervical cancer progression. PLoS ONE 4: e5137. doi: 10.1371/journal.pone. 0005137.
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