Oridonin Triggers Chaperon-mediated Proteasomal Degradation of BCR-ABL in Leukemia

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Targeting oncoprotein degradation offers a strategy to overcome drug resistance in cancer.
• Oridonin is a natural compound with demonstrated antitumor effects, but its precise molecular targets and mechanisms are not fully understood.

Purpose of the Study:

• To elucidate the mechanism by which oridonin induces oncoprotein degradation.
• To identify the direct cellular targets of oridonin and its role in leukemia treatment.

Main Methods:

• Investigated oridonin's effect on BCR-ABL degradation in leukemia cells.
• Utilized biochemical assays to identify oridonin's interaction with HSF1 (Heat Shock Factor 1) and the chaperone system.
• Performed cell culture and mouse xenograft models to assess in vivo efficacy.

Main Results:

• Oridonin induces oxidative stress and directly binds to HSF1 cysteines, activating the chaperone system.
• Activation of HSF1 leads to increased HSP70 and ubiquitin, facilitating BCR-ABL degradation via the ubiquitin-proteasome pathway.
• Oridonin effectively degrades both wild-type and mutant BCR-ABL, showing efficacy in imatinib-sensitive and -resistant leukemia models.

Conclusions:

• Oridonin triggers BCR-ABL degradation through a novel HSF1-mediated chaperone and ubiquitin-proteasome pathway.
• Oridonin acts as a pharmaceutical activator of HSF1, presenting a promising therapeutic strategy for leukemia, including resistant forms.