Comparison of three dimensional and three step MTT assay and sulforhodamine B assay for tumour chemo sensitivity testing

Objective:To comparethe value of self establishedthree dimensional and three step MTT assay (3D3S MTT assay), MTT assay and Sulforhodamine B (SRB) assay for tumor chemosensitivity testing Methods:Hep G2, T 24 and SKOV3 cell lineswereexposed to Adriamycin and Mitomycin C for 3 days with different further culture durationand then carried out the above three methods For MTT assay and SRB assay the equation to calculate the percentage of tumour growth inhibition (%TGI) is: %TGI=[1 A t /A c ]×100% According to the self establishedmathematical model, the equation for 3D3S MTT assay is: %TGI=1 {\[lnA max ln(A max A t )\]/\[lnA max ln(A max A c )\]} 1/b ×100% Results: S shaped drug response curves were showed in all the above three methods Comparison of the results of %TGIand IC 50 show that %TGIpredicted by MTT assay is lower than that by SRB assay or 3D3S MTT assay, and IC 50 predicted by MTT assay is in average 3 to 5foldsof that by SRB assay or 3D3S MTT assay %TGIand IC 50 predicted by 3D3S MTT assay is approximately the same value as predicted by SRB assay Conclusion:3D3S MTT assay is applicable for in vitro tumor chemosensitivity testing, which is a successful solution to the 3 to 5 foldsunderestimation of chemosensitivity of MTT assay compared with SRB assay