Hi to all,
I have performed an HepG2 cell proliferation assay on 14 soil samples from two sites in the north of Italy. I have exposed cells to water soluble extracts of soil (soil suspension in water (soil water ratio 1:4 w/v ), sonicated for 1 hour, deposited for 24 h and sonicated for 1 h... centrifuged and liophilized).
After 24h and 72 hours of exposure I have recorded a proliferative effects in most o f the samples. Cells are more than 120% respetc to their control (untreated). In some sample the stimulation effect is present at low dose, in other samples the effects are present in all the tested doses.
Someone have articles or works that I can cite about this proliferative effects?
Are metals able to promote proliferation?
What compound can be responsible of these effects?
I have hypothesized that there are some phytoormones which can promote proliferation... I think that these compounds are not estradiol-like compounds because HepG2 do not express ER receptors.
Please help me!
Lantanides (lanthanum and cerium e.g.) are metals that act as growth promoters and are used for pig poultry production . They are ubiquitous in soils, and I' m sure that they promote proliferation of HepG2 cells cause I ' m performing a study about La and Ce effects oh human and animal cells. Heavy metals such as lead and cadmium are contaminants with opposite effects,cause they exert toxicity on cells.
However other substances than metals could have caused the proliferation of your cell line, were the soils analysed before your cellular tests?
Regards
Stefania
Thank you StEfania for the response... do you have some references about your studies???
Finally, I do not understand your final questions...
I have tested organic extracts of the same soils (agrarian and urban soils) on HepG2 obatined a clear dose-response curves wwith additional time dependent effects...
while the water soluble extracts of the same soils promoted proliferation at low doses in most of the treatment... and two sites promoted porliferation at all the tested doses...
I will contact you by direct messagging here... so we could have some exchange... in italian... moreover I'd like to know what kind of lines are you using...
How do you measure proliferation? By cell number, or do you use a water-soluble tetrazolium-based assay (e.g. Wst-1)? The latter may give different results than a cell count.
Dear Angela
I use MTS (like MTT or WST-1) but the results are in accorance with visualization at the microscope and count.
Have you tried calculating the OD value per the cell number from the same culture? Sometimes the appararent accordance may be misleading in quantitative terms.
As to your example with a 20% increase at a low concentration, this might be down to a "hormetic effect", where small concentrations of a stressful compound (something that activates one or more of the cells 7 stress-response pathways), such as oxidative compounds (e.g. metals), can give rise to a small improvement in health (such as metabolic activity) and/or proliferative capacity (both giving rise to a higher MTT-value). For this to be true, the compound, or in your case a combination of many different compounds, should be cytotoxic at higher doses. The fact that soil contains lots of different compounds, which each could act hormetically/cytotoxically at different doses (+ possible contribution by growth factors or inhibitors) will make any interpretation problematic though. For further reading on the subject of Hormesis I suggest looking up reviews made by Edward Calabrese and/or Suresh I S Rattan. Finally, have you tried heat-inactivation of the possible protein-content (hormones), to see whether these are causing the effect?
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