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bioRxiv · 10.1101/2021.02.05.429931

Cancer cells adapt FAM134B-BiP complex mediated ER-phagy to survive hypoxic stress

Chipurupalli, S.·Ganesan, R.·Martini, G.·Mele, L.·Kannan, E.·Namasivayam, V.·Desiderio, V.·Robinson, N.
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Abstract

In a tumor microenvironment cancer cells experience hypoxia resulting in the accumulation of misfolded/unfolded proteins in the endoplasmic reticulum (ER) which elicit unfolded protein response (UPR) as an adaptive mechanism. UPR activates autophagy enabling the degradation of misfolded/unfolded proteins. More recently, ER-specific autophagy has been implicated in the removal of damaged ER and restoration of ER-homeostasis. Our investigations reveal that during hypoxia induced ER-stress, the ER-phagy receptor FAM134B targets damaged portions of ER into autophagosomes to restore ER-homeostasis in cancer cells. Loss of FAM134B in breast cancer cells results in increased ER-stress and reduced cell proliferation. Mechanistically, upon sensing hypoxia activated proteotoxic stress, the ER chaperone BiP forms a complex with FAM134B and promotes ER-phagy. Our studies have further led to the identification of a pharmacological agent vitexin that disrupts FAM134B-BiP complex thereby inhibits ER-phagy and suppresses breast cancer progression in vivo.

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Chipurupalli, S., Ganesan, R., Martini, G., Mele, L., Kannan, E., Namasivayam, V., Desiderio, V., Robinson, N.. 2021-02-06. Cancer cells adapt FAM134B-BiP complex mediated ER-phagy to survive hypoxic stress. https://doi.org/10.1101/2021.02.05.429931

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