Seminar Title:
Clusterin and mitophagy: A potential avenue for targeting oral cancer
Seminar Type:
Departmental Seminar
Department:
Life Science
Speaker Name:
Prof. Sujit Kumar Bhutia
Speaker Type:
Faculty
Venue:
LS Seminar Hall
Date and Time:
13 Nov 2024 11:00 AM
Contact:
2787
Abstract:
Clusterin (CLU) is an evolutionary conserved molecular chaperone present in different human
tissues and fluids and established to be a significant cancer regulator. Here, we showed that
CLU (clusterin) is localized to mitochondria to induce mitophagy controlling mitochondrial
damage in oral cancer cells. CLU acts as an adaptor protein that coordinately interacts with
BAX and LC3 recruiting autophagic machinery around damaged mitochondria in response to
cisplatin treatment. Interestingly, CLU triggers class III phosphatidylinositol 3-kinase
(PtdIns3K) activity around damaged mitochondria, and inhibition of mitophagic flux causes
the accumulation of excessive mitophagosomes resulting in reactive oxygen species (ROS)-
dependent apoptosis during cisplatin treatment in oral cancer cells. Moreover, CLU exhibits its
mitophagy-specific role in clearing damaged mitochondria in cancer stem cells (CSCs) in oral
cancer. CLU also regulates mitochondrial fission by activating the Ser/Thr kinase AKT, which
triggered phosphorylation of DNM1L/Drp1 at the serine 616 residue initiating mitochondrial
fission. More importantly, we also demonstrated that CLU-mediated mitophagy positively
regulates oral CSCs through mitophagic degradation of MSX2 (msh homeobox 2), preventing
its nuclear translocation from suppressing SOX2 activity and subsequent inhibition of cancer
stemness and self-renewal ability. However, CLU knockdown disturbed mitochondrial
metabolism generating excessive mitochondrial superoxide, which improves the sensitivity to
cisplatin in oral CSCs. Notably, our results showed that CLU-mediated cytoprotection relies
on SOX2 expression. SOX2 inhibition through genetic (shSOX2) and pharmacological (KRX0401) strategies reverses CLU-mediated cytoprotection, sensitizing oral CSCs toward
cisplatin-mediated cell death.