Shifting of entire cell cycle to the left - (Aug/20/2009 )

Hi all,

I'm just wondering if anyone has any suggestions re my problem.
I am running PI cell cycle on cells after been treated with a growth factor and then treated with mitoxantrone.
As I increase conc of Mitoxantrone I see a conc dependent shift of the entire cell cycle distribution peaks to the left (i.e. SubG1-G0/G1-S-G2/M still visible).
The trend of the peaks are staying the same but they move significantly to the left when compared to untreated cells.
I was under the impression that Mitoxantrone causes apoptosis which would cause DNA fragmentation and an increase in sub G1? But i'm just seeing this shift and no increase in sub G1?
Anyone have any ideas??
Thanks a lot
Kevin

-reds_23-

Thanks so much for useful info

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-kennedyusa-

I don't really have an explanation for your observation, but a flow cytometry expert told me that when using different drugs, I should always adjust the voltage of PI so that the G1 peak always has the same value in order to get comparable results. He said that it is normal that drugs influence the fluorescence intensity of PI. As long as you see the peaks clearly, you shouldn't pay much attention to the shift but instead adjust the voltage settings so that afterwards you can overlay treated and untreated cells.

-illuminated-

reds_23 on Aug 20 2009, 04:55 PM said:

from wikipedia : Mitoxantrone is a type II topoisomerase inhibitor; it disrupts DNA synthesis and DNA repair in both healthy cells and cancer cells. It also engages in intercalation

it is not possible that, since you see a dose dependent shift to the left, Mitoxantrone induces somehow a reduced accessibility of PI to the dsDNA? have you ever seen this shift with other drugs that affect the DNA stucture/synthesis?

-canotto-