Identification of Nrf2/STAT3 axis in induction of apoptosis through sub‐G 1 cell cycle arrest mechanism in HT‐29 colon cancer cells

• Published in: Journal of cellular biochemistry 2019-08, Vol.120 (8), p.14035-14043
• Main Authors: Tajmohammadi, Issa, Mohammadian, Jamal, Sabzichi, Mehdi, Mahmuodi, Shiva, Ramezani, Mina, Aghajani, Marjan, Ramezani, Fatemeh
• Format: Article
• Language: English
• Subjects: 5‐fluorouracil; apoptosis; Apoptosis - drug effects; bcl-2-Associated X Protein - metabolism; bcl-X Protein - metabolism; Cell Proliferation - drug effects; Cell Survival - drug effects; colon cancer; Colonic Neoplasms - metabolism; Colonic Neoplasms - pathology; combination chemotherapy; combination index; Cyclic S-Oxides - pharmacology; Drug Synergism; Fluorouracil - pharmacology; G1 Phase Cell Cycle Checkpoints - drug effects; Gene Expression Regulation, Neoplastic - drug effects; HT29 Cells; Humans; Inhibitory Concentration 50; NF-E2-Related Factor 2 - metabolism; nuclear factor erythroid 2–related factor 2; RNA, Messenger - genetics; RNA, Messenger - metabolism; signal transducer and activator of transcription 3; STAT3 Transcription Factor - metabolism; stattic
• ISSN: 0730-2312; 1097-4644; 1097-4644
• DOI: 10.1002/jcb.28678

We investigated the role of stattic as an adjuvant molecule to increase the cytotoxicity of 5‐fluorouracil (5‐FU) through specific inhibition of molecular targets, signal transducer and activator of transcription 3 (STAT3) and nuclear factor erythroid 2–related factor 2 (Nrf2) in HT‐29 colon cancer cells. Cytotoxicity and apoptotic effects were investigated by methylthiazolyldiphenyl‐​tetrazolium bromide assay and flow cytometry analysis, respectively. Real‐time polymerase chain reaction was applied to assess the messenger RNA (mRNA) level of STAT3, Nrf2, and apoptotic genes including Bax, Bcl‐xl, and Bcl‐2. The antitumor effect of 5‐FU in combination with stattic induced synergistic effect in HT‐29 cells with combination indexes (CIs) 0.49. Flow cytometric results related to apoptotic confirmed that there was up to 40% increase in the population of apoptotic cells in HT‐29 colon cancer cells incubated with 5‐FU and stattic compared with control groups. Our data from gene expression determined a substantial diminish in the mRNA levels of the Nrf2 and antiapoptotic gene Bcl‐2 along with a noticeable increase in the level of the proapoptotic Bax in HT‐29 colon cells that underwent cotreatment with 5‐FU and stattic (P < 0.05). Moreover, the results exhibited that stattic can be used as adjuvant chemotherapy besides the 5‐FU. This therapeutic approach in colon cancer could mediate 5‐FU chemoresistance via modulating therapeutic targets (ie, STAT3 and Nrf2 pathways) and decreased 5‐FU‐related adverse effects. Stattic boosts the 5‐fluorouracil behavior in human colon cancer