Penta-O-Galloyl- β-D-Glucose in Pistacia integerrima Targets AMPK-ULK1 and ERK/STAT3 Signaling Axes to Induce ROS-Independent Autophagic Cell Death in Human Lung Cancer Cells

Acharya Balkrishna; Vallabh Prakash Mulay; Sudeep Verma; Jyotish Srivastava; Savita Lochab; Anurag Varshney

doi:10.3389/fphar.2022.889335

Penta-O-Galloyl- β-D-Glucose in Pistacia integerrima Targets AMPK-ULK1 and ERK/STAT3 Signaling Axes to Induce ROS-Independent Autophagic Cell Death in Human Lung Cancer Cells

Front Pharmacol. 2022 Jul 19:13:889335. doi: 10.3389/fphar.2022.889335. eCollection 2022.

Authors

Acharya Balkrishna^{1

2

3}, Vallabh Prakash Mulay¹, Sudeep Verma¹, Jyotish Srivastava¹, Savita Lochab¹, Anurag Varshney^{1

2

4}

Affiliations

¹ Drug Discovery and Development Division, Patanjali Research Institute, Haridwar, India.
² Department of Allied and Applied Sciences, University of Patanjali, Patanjali Yog Peeth, Haridwar, India.
³ Patanjali Yog Peeth (UK) Trust, Glasgow, United Kingdom.
⁴ Special Centre for Systems Medicine, Jawaharlal Nehru University, New Delhi, India.

Abstract

Natural molecules have promising perspectives as adjuvants to chemotherapies against cancer. Pistacia chinensis subsp. Integerrima (hereafter, Pistacia integerrima) traditionally known for medicinal values in respiratory disorders was tested for anti-lung cancer properties. The extract prepared from Pistacia integerrima (PI) selectively impaired the viability of lung cancer cells, A549 and NCI-H460, compared to non-cancer cells. At non-lethal concentrations, PI mitigated colony-forming, spheroid formations and metastatic properties of lung cancer cells. As a step toward identifying the phytomolecule that is imparting the anti-lung cancer properties in PI, we subjected the extract to extensive characterization through UPLC/QToF-MS and further validated the findings with UHPLC. The gallotannin, penta-O-galloyl-β-D-glucose (PGG), among others, was identified through UPLC/QToF-MS. PGG exhibits potential chemopreventive effects against various cancer types. However, a defined mechanism of action of PGG in restricting lung cancer progression is still unexplored. Bioactivity-guided column fractionations enabled the determination of PGG as the major phytochemical that governed PI-mediated AMPK-ULK1-dependent autophagy and apoptosis, albeit independent of intracellular ROS activation. Interestingly, the autophagy flux when inhibited restored the cell viability even in the presence of PI. The study further delineated that PI and PGG activated ERK and inhibited STAT3 to trigger apoptosis through caspase-3 and PARP 1 pathways. Collectively, the finding demonstrates that plant extract, PGG, in the PI extract effectively combats lung cancer progression through autophagic cell death by altering ERK/AMPK-ULK1/STAT3 signaling axes. The study proposes PGG as a potential AMPK activator and STAT3 inhibitor that can be exploited further in developing adjuvant chemotherapeutics against lung cancer.

Keywords: AMPK activator; Pistacia integerrima; STAT3 inhibitor; UPLC/Q-TOF-MS; autophagic cell death; lung cancer; natural molecules; penta-O-galloyl-β-D-glucose.