Cardamonin represses proliferation, invasion, and causes apoptosis through the modulation of signal transducer and activator of transcription 3 pathway in prostate cancer

The pleiotropic transcription factor, signal transducer and activator of transcription 3 (STAT3) is often aberrantly activated in a wide variety of cancers and plays a pivotal role in tumor initiation, promotion and progression. Targeting deregulated STAT3 activation by small molecule inhibitors is generally considered as an important therapeutic strategy. Hence, in the present study, we evaluated the potential of cardamonin (CD), a 2',4'-dihydroxy-6'-methoxychalcone, to modulate STAT3 activation in prostate cancer (PC) cells and found that this chalcone can indeed exhibit significant anticancer effects through negatively regulating STAT3 activation by diverse molecular mechanism(s). CD suppressed STAT3 phosphorylation, nuclear translocation and DNA binding ability in PC cells. Computational modeling revealed that CD can bind directly to the Src Homology 2 domain of STAT3 and also effectively inhibit its dimerization. CD was also found to significantly reduce the migratory/invasive potential of PC cells through the downregulation of various oncogenic proteins. Overall, the data indicates that the potential application of CD as a STAT3 blocker can mitigate both the growth and survival of PC cells.