Structure-activity relationship (SAR) of withanolides to inhibit Hsp90 for its activity in pancreatic cancer cells

Abstract

Withaferin A (WA), a naturally occurring steroidal lactone, directly binds to Hsp90 and leads to the degradation of Hsp90 client protein. The purpose of this study is to investigate the structure activity relationship (SAR) of withanolides for their inhibition of Hsp90 and anti-proliferative activities in pancreatic cancer cells. In pancreatic cancer Panc-1 cells, withaferin A (WA) and its four analogues withanolide E (WE), 4-hydroxywithanolide E (HWE), 3-aziridinylwithaferin A (AzWA) inhibited cell proliferation with IC50 ranged from 1.0 to 2.8 μM. WA, WE, HWE, and AzWA also induced caspase-3 activity by 21-, 6-, 11- and 15-fold, respectively, in Panc-1 cells, while withaperuvin (WP) did not show any activity. Our data showed that WA, WE, HWE, and AzWA, but not WP, all directly bound to Hsp90 and induced Hsp90 aggregation, hence inhibited Hsp90 chaperone activity to induce degradation of Hsp90 client proteins Akt and Cdk4 through proteasome-dependent pathway in pancreatic cancer cells. However, only WA, HWE and AzWA disrupted Hsp90-Cdc37 complexes but not WE and WP. SAR study suggested that the C-5(6)-epoxy functional group contributes considerably for withanolide to bind to Hsp90, inhibit Hsp90 chaperone activity, and result in Hsp90 client protein depletion. Meanwhile, the hydroxyl group at C-4 of ring A may enhance withanolide to inhibit Hsp90 activity and disrupt Hsp90-Cdc37 interaction. These SAR data provide possible mechanisms of anti-proliferative action of withanolides.

Synergistic antileukemic therapies in NOTCH1 -induced T-ALL

“…However, we have not observed development of resistance in vitro after sustained treatment with DBZ plus withaferin A in any of our models, suggesting that T-ALL cells need to overcome significant barriers to develop resistance to this combination. Mechanisms proposed for the antitumor effects of withaferin A include proteasome (24), HSP90 (25), NFKB (26) inhibition, and induction of reactive oxygen species (ROS) (27). However, these mechanisms seem to be cell-type specific, as functional assays revealed decreased ROS levels and no or minimal impact of withaferin A in HSP90, proteasome, or NFKB activity in T-ALL cells (SI Appendix, Fig.…”

Solid State Characterization of <i>Withania somnifera</i> (Ashwagandha) Root Extract After Treatment with Consciousness Energy Healing

“…The broad peak at 3600-3200 cm -1 may be due to the O-H functional group frequency of the hydroxyl groups present in phytoconstituents present in the ashwagandha root extract. The presence of epoxide, unsaturated lactone, 1-keto-2-ene functions plays a vital role to elicit the pharmacological activities of withanolides [14,[55][56][57]. In summary, FT-IR results suggest that there was a little impact of Consciousness Energy Healing Treatment on W. somnifera at the atomic level to reduce the force constant of O-H (str.)…”

Influence of the Biofield Energy Healing Treatment on Physicochemical, Thermal and Behavioral Properties of Ashwagandha (<i>Withania somnifera</i>) Root Extract

“…The vibrational frequencies for C=O, C-O, and C-C groups in the Biofield Energy Treated sample was observed with respect to the control sample. The presence of epoxide, unsaturated lactone, 1-keto-2-ene functions play a vital role to elicit the pharmacological activities of Thermal and Behavioral Properties of Ashwagandha (Withania somnifera) Root Extract withanolides [14,[55][56][57]. This results revealed that the force constant for the functional groups present in the phytoconstituents was altered compared with the control sample.…”