Carcinogenesis, 2019, Vol. 40, No. 6, 791–804 doi:10.1093/carcin/bgy176 Advance Access Publication December 8, 2018 Original Article 791 © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com. Received: April 2, 2018; Revised: November 6, 2018; Accepted: December 5, 2018 Original Article 7-hydroxyfrullanolide, isolated from Sphaeranthus indicus, inhibits colorectal cancer cell growth by p53-dependent and -independent mechanism Praveen Pandey 1 , Deepika Singh 2 , Mohammad Hasanain 1,3 , Raghib Ashraf 1,5 , Mayank Maheshwari 1 , Kuldeep Choyal 1 , Akhilesh Singh 1 , Dipak Datta 1,3 , Brijesh Kumar 2,3 and Jayanta Sarkar 1,3,4, * 1 Biochemistry Division, 2 Sophisticated Analytical Instrument Facility, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, Uttar Pradesh 226 031, India, 3 Academy of Scientifc and Innovative Research, Ghaziabad, Uttar Pradesh 201 002, India and 4 Laboratory Animal Facility, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, Uttar Pradesh 226 031, India 5 Present address: National Centre for Biomolecular Research, Masaryk University, Brno 62500, Czech Republic *To whom correspondence should be addressed. Biochemistry Division, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, Uttar Pradesh 226 031, India. Tel: +91-522-2772450 ext. 4349; Fax: +91-522-2771941; Email: j_sarkar@cdri.res.in, jayantavirol@gmail.com Correspondence may also be addressed to Brijesh Kumar. Tel: +91-522-2772457; Fax: +91-522-2771941; Email: brijesh_kumar@cdri.res.in Abstract Sphaeranthus indicus Linn. is commonly used in Indian traditional medicine for management of multiple pathological conditions. However, there are limited studies on anticancer activity of this plant and its underlying molecular mechanisms. Here, we isolated an active constituent, 7-hydroxyfrullanolide (7-HF), from the fowers of this plant, which showed promising chemotherapeutic potential. The compound was more effective in inhibiting in vitro proliferation of colon cancers cells through G 2 /M phase arrest than other cancer cell lines that were used in this study. Consistent with in vitro data, 7-HF caused substantial regression of tumour volume in a syngeneic mouse model of colon cancer. The molecule triggered extrinsic apoptotic pathway, which was evident as upregulation of DR4 and DR5 expression as well as induction of their downstream effector molecules (FADD, Caspase-8). Concurrent activation of intrinsic pathway was demonstrated with loss of ΔΨm to release pro-apoptotic cytochrome c from mitochondria and activation of downstream caspase cascades (Caspase -9, -3). Loss of p53 resulted in decreased sensitivity of cells towards pro-apoptotic effect of 7-HF with increased number of viable cells indicating p53-dependent arrest of cancer cell growth. This notion was further supported with 7-HF-mediated elevation of endogenous p53 level, decreased expression of MDM2 and transcriptional upregulation of p53 target genes in apoptotic pathway. However, 7-HF was equally effective in preventing progression of HCT116 p53 +/+ and p53 −/− cell derived xenografts in nude mice, which suggests that differences in p53 status may not infuence its in vivo effcacy. Taken together, our results support 7-HF as a potential chemotherapeutic agent and provided a new mechanistic insight into its anticancer activity. Introduction With an incidence rate of 1.3 million new cases every year (1), colorectal cancer (CRC) is the third most common cancer worldwide and one of the leading causes of cancer related death (http://globocan.iarc.fr/). CRC cells primarily metastasize in liver owing to the hepatic portal venous drainage of colon and rectum (2). Surgery is the preferred mode of treatment for Downloaded from https://academic.oup.com/carcin/article/40/6/791/5235624 by guest on 21 July 2022