On the higher concentration,bortezomib,doxorubicin and daunorubicin brought about a greater than 20-fold induction of caspase 3/7 action ,whereas bortezomib,camptothecin,and CDDO-Me caused a greater than 20-fold up-regulation of caspase 3/7 activity on the lower concentration.Nearly all compounds TH-302 distributor stimulated apoptosis additional by extra than 2-fold at either concentration.Some agents,this kind of as helenalin,perezone,CDDO-Me,arsenic trioxide,PD 0332991,& amonafide with the large concentrations and topotecan & Epoxy anthraquinone derivative in the lower concentrations,were considered active on SK-N-AS and SH-SY5Y by the cell viability assay but induced caspase 3/7 exercise at a lesser extend.Monitoring growth inhibition profiles in real time Eight compounds showed discordant results where the reduced cell number was evident by cell titer blue but marginal presence or absence of activated caspase 3/7.In order to investigate the cause of these discordant results,we therefore used RT-CES method to continuously monitor the cell growth profiles for 72 hours following the addition of the 30 drugs active against NB cell lines on the large and minimal concentrations..
We observed that helenalin,perezone,and CDDO-Me with the large concentration caused rapid decline in cell number within a few hours after the drug addition.Therefore,there probably hardly any viable cells left for the caspase 3/7 assay Ruxolitinib at 24hrs after drug addition.Arsenic trioxide,amonafide,and PD 0332991 on the large concentration as well as EAD and topotecan with the lower concentration triggered gradual reduction in the cell numbers,as evident by the RT-CES growth inhibition profiles; and it is consistent with a lesser degree of induction of caspase3/7 measured at 24 hours after drug addition.Cucurbitacin I inhibits neuroblastoma cell growth through inhibition of STAT3 We have shown that Cucurbitacin I was active against NB cells,and it has been described as a specific inhibitor of STAT3 in multiple tumor cells 10; 11 and so this drug may prove to be a potential agent against high-risk neuroblastoma.We here further examined the cell growth inhibition and pro-apoptotic exercise of Cucurbitacin I using different doses of drugs in a larger panel of NB cell lines including two MYCN-amplified cell lines and three MYCN-not-amplified cell lines.The inhibition of cell growth was observed for all tested cell lines in a dose-dependent manner ,and the induction of apoptosis was shown at a dose of 100 nM or higher.We next examined if this drug also suppressed cell growth by inhibiting STAT3 activation in neuroblastoma cells.As shown in Figure 5C,Cucurbitacin I reduced STAT3 total protein expression level in SK-N-AS,NBEB,and SH-SY5Y cells.More importantly,Cucurbitacin I also inhibited phosphorylation of STAT3 in dose-dependent manner in all 4 cell lines.These results confirmed that Cucurbitacin I inhibited NB cell growth through inhibition of STAT3 activation.