# MTT assay with docetaxel and LNcap cells biphasic growth - (Dec/31/2006 )

HI, all

I need a help here. I am growing LNcap cells and treating with diffrent concentration of docetaxel. The MTT result shos that docetaxel behaves in a biphasic manner.

experment 1) Left couumn is dose of docetaxel and right side is the response in percentage to the control.(basically percentage survival of cells)
0 100
0.0625uM 60.14824775
0.125uM 59.44357571
0.25 57.99234068
0.5 45.58768253
1 35.23732537

Experiment 2)
0 100
0.0625uM 45.47929195
0.125uM 52.08651729
0.25 54.14265039
0.5 44.14178909
1 40.73028774

You can note that in the second experement it clearly behaves in a biphasic manner. now my question is how to calculate the IC50% here. I have no curve fitting into that.

In the second experiment I suspect the IC50 dose of docetaxel is between 0 and 0.0625uM. How to calculate this please.

-irr-

QUOTE (irr @ Dec 31 2006, 12:12 PM)
HI, all

I need a help here. I am growing LNcap cells and treating with diffrent concentration of docetaxel. The MTT result shos that docetaxel behaves in a biphasic manner.

experment 1) Left couumn is dose of docetaxel and right side is the response in percentage to the control.(basically percentage survival of cells)
0 100
0.0625uM 60.14824775
0.125uM 59.44357571
0.25 57.99234068
0.5 45.58768253
1 35.23732537

Experiment 2)
0 100
0.0625uM 45.47929195
0.125uM 52.08651729
0.25 54.14265039
0.5 44.14178909
1 40.73028774

You can note that in the second experement it clearly behaves in a biphasic manner. now my question is how to calculate the IC50% here. I have no curve fitting into that.

In the second experiment I suspect the IC50 dose of docetaxel is between 0 and 0.0625uM. How to calculate this please.

What is the reported IC50 of this drug for this cell line?

You only gave us a partial data (mean, I assume), what about your +/- SD and n, and initial cell density? SD and n can provide an indication how well these experiments were conducted and cell density has a great influrance on drug sensitivity. Also, more data points maybe needed between 0 and 0.0625.

-genehunter-1-

QUOTE (genehunter-1 @ Dec 31 2006, 01:48 PM)
QUOTE (irr @ Dec 31 2006, 12:12 PM)
HI, all

I need a help here. I am growing LNcap cells and treating with diffrent concentration of docetaxel. The MTT result shos that docetaxel behaves in a biphasic manner.

experment 1) Left couumn is dose of docetaxel and right side is the response in percentage to the control.(basically percentage survival of cells)
0 100
0.0625uM 60.14824775
0.125uM 59.44357571
0.25 57.99234068
0.5 45.58768253
1 35.23732537

Experiment 2)
0 100
0.0625uM 45.47929195
0.125uM 52.08651729
0.25 54.14265039
0.5 44.14178909
1 40.73028774

You can note that in the second experement it clearly behaves in a biphasic manner. now my question is how to calculate the IC50% here. I have no curve fitting into that.

In the second experiment I suspect the IC50 dose of docetaxel is between 0 and 0.0625uM. How to calculate this please.

What is the reported IC50 of this drug for this cell line?

You only gave us a partial data (mean, I assume), what about your +/- SD and n, and initial cell density? SD and n can provide an indication how well these experiments were conducted and cell density has a great influrance on drug sensitivity. Also, more data points maybe needed between 0 and 0.0625.

Thanks. This is pooled data of 3 experiments and SE is within acceptable limits. Each concentration and in each experiments done three wells. cell density was 10000/well, which was optimised after a series of experiments. I could not find a reported IC50 for the cell line and drug. What I have is evidence to say that docetaxel behaves in a biphasic manner. The data I have given is mean of means of three experiments converted in to percentage of control.

The experiment one is cells+docetaxel only
The experiment 2 is cells+docetaxel+drugA.

I am looking whether addition of drug A decreased IC50 of Docetaxel. Experiment 1 it is around 0.5 and 0.25uM and inthe experiment 2 it between 0 and 0.0625. However there is one more IC50 value falls between 0.5 and 0.25.

I think I have to consider the first downward trend and calculate the IC50. But how to calculate using the Excel please? or suggest alternate ways for me please.

Sincerely

-irr-