General Evaluation

Sources of Error and uncertainty in this experiment includes pipetting the doses of drug into the wrong rows or columns, which would have rendered the data collected with the MTS Assay incorrect. Since this experiment was done in duplicate however, an error of this type would not have affected the experimental results very much.

Another error would include the clumping of cells while pipetting them into separate wells. Under the hemocytometer, we noticed that some of the cell lines had cells that clumped together, and thus, this would have caused some wells to contain more cells than others. However, this error was mostly avoided by distributing the cells randomly.

Furthermore, precipitate formation and a varying pH may have also affected the growth of the cancer cells as well as the absorption of the MTS Assay. Thus, these two errors were avoided by buffering the IP6, so as to lower its pH, and by subtracting the background absorbance from each absorbance in the results. The background absorbance was the row of wells at the top of each plate, which contained only medium and drug.

Finally, we had questions why LNCaP did not show synergism between the two drugs. This may be because LNCaP is a certain cell line, which does not react as well to the drugs as 983M cells do, or it may be because of the condition of the LNCaP. Since our mentor, Dr. Hitt, had just moved to the University of Alberta from Ontario, the cells had suffered much movement and were shaken badly. This would have affected the viability of the cells as well as their proliferation rate. Knowing this problem, we tried to redo the LNCaP cells after a few weeks and allowing them to grow back, but this did not seem to help very much.