Withaferin A inhibits lysosomal activity to block autophagic flux and induces apoptosis via energetic impairment in breast cancer cells

Nethaji Muniraj, Sumit Siddharth, Arumugam Nagalingam, Alyssa Walker, Juhyung Woo, Balázs Gyorffy, Ed Gabrielson, Neeraj K. Saxena, DIpali Sharma

Research output: Contribution to journalArticle

Abstract

Withaferin A (WFA), a steroidal lactone, negatively regulates breast cancer growth however, its mechanisms of action remain largely elusive. We found that WFA blocks autophagy flux and lysosomal proteolytic activity in breast cancer cells. WFA increases accumulation of autophagosomes, LC3B-II conversion, expression of autophagy-related proteins and autophagosome/lysosome fusion. Autolysosomes display the characteristics of acidic compartments in WFA-treated cells; however, the protein degradation activity of lysosomes is inhibited. Blockade of autophagic flux reduces the recycling of cellular fuels leading to insufficient substrates for tricarboxylic acid (TCA) cycle and impaired oxidative phosphorylation. WFA decreases expression and phosphorylation of lactate dehydrogenase, the key enzyme that catalyzes pyruvate-to-lactate conversion, reduces adenosine triphosphate levels and increases AMP-activated protein kinase (AMPK) activation. AMPK inhibition abrogates while AMPK activation potentiates WFA's effect. WFA and 2-deoxy-d-glucose combination elicits synergistic inhibition of breast cancer cells. Genetic knockout of BECN1 and ATG7 fails to rescue cells from WFA treatment; in contrast, addition of methyl pyruvate to supplement TCA cycle protects WFA-treated cells. Together, these results implicate that WFA is a potent lysosomal inhibitor; energetic impairment is required for WFA-induced apoptosis and growth inhibition and combining WFA and 2-DG is a promising therapeutic strategy for breast cancer.

Original languageEnglish (US)
Pages (from-to)1110-1120
Number of pages11
JournalCarcinogenesis
Volume40
Issue number9
DOIs
StatePublished - Sep 1 2019

ASJC Scopus subject areas

  • Cancer Research

Fingerprint Dive into the research topics of 'Withaferin A inhibits lysosomal activity to block autophagic flux and induces apoptosis via energetic impairment in breast cancer cells'. Together they form a unique fingerprint.

  • Cite this