Here is an example :
concentration Average Percentage viability in normal cell line
0.1 100
1 98.23
10 90.45
100 80.56
200 70.65.
When we calculate IC:50 , we get 342.07.
Imagine a scenario ,where my cells are highly resistant to drug .. suppose when i increased the concentration from 200-1000 my % of viability didnt change i.e 70.65 even at 1000..
Is it advisable to assume IC:50 just by maths Y = mx + C ,Without trying it in MTT.
No, you have no idea what the slope of the curve after your last datapoint would be.
btw, you don't expect a linear decrease in viability, but an S-shape'd curve...
I fully share Arnoud's opinion.
When you face such a situation, you do not know whether it is due to the compound or to the cell line used.
In the attached articles, you will see more than strange behavior of one glioma cell line towards classical anticancer agents.
So, if you want to show your data, it is better to present the curve of growth inhibition rather than calculating an hypothetical IC50.
Best regards
Robert
Hi Suresh,
I agree with Arnoud and Robert. You may find the links attached below helpful.
https://www.researchgate.net/post/Can_anyone_give_me_details_for_the_calculation_of_LC50_LD50_IC50_of_drugs_against_cultured_cancerous_cells
http://www.ncbi.nlm.nih.gov/pubmed/17352213
http://www.graphpad.com/support/faqid/1356/
Dear Suresh,
I viewed your question. Usually resistant cells already much aware and creates alternative defensive system against your exposed drug. So try to increase the concentration of your drug to assess cell viability or else you can calculate IC50 value what you already got your % inhibition data by using non-linear regression analysis (dose-response inhibition analysis in graphpad prism software). All the best.
with regards,
Manigandan
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