This appears that it is inducing cell cycle arrest at S phase , if cells are accumulating at this phase. Further, is it inducing any cell death as might be represented by sub G0-G1 peak.

Hello,

I agree with Asif. You should analyse ale phases of the cell cycle (G0/G1, S, G2/M and sub-G1). The most probable cause is either cell cycle arrest (if you observe an increase in any other phase, e.g. G1 or S) or e.g. apoptosis that (in this assay) can be observed as increasing number of events in sub-G1 region. But remember. It strongly depends on the cell type, the substance you're using, the time of incubation he cells with the substance.

Anyway, start with analysing the DNA histogram.

Best regards,

Robert

I totally agree with both the suggestions above. Moreover, if there is a cell cycle arrest, it must lead to an increase in S phase peak (S phase should be made pretty much distinct by optimum gating). This would confer an "S-Phase block", provided the peak intensity of G1-phase doesn't change (mostly increase) significantly. If it is so, then in the next step you might consider to check the cell cycle checkpoints/proteins responsible for this block by doing e.g. Western Blotting, and at transcriptional levels through RT-PCR.

There is although another aspect as mentioned above, that is the appearance of a clear Sub-G1 peak, which represents cell death. A dose dependent study (a-e uM) would give a better understanding. In that case you may next consider doing the Annexin-V - PI assay where the notion of early or/and late apoptosis is further confirmed. For apoptosis being the sole cause, the arrest in S- Phase might not be evident at times. So, to confirm apoptosis you may consider doing a couple of more assays that are usually followed.

All the very best!