Piperlongumine induces apoptosis and autophagy in human lung cancer cells through inhibition of PI3K/Akt/mTOR pathway.

Piperlongumine (PL), a natural alkaloid present in the fruit of the Long pepper, is known to exhibit notable anti-cancer effects. Nonetheless, the anti-tumor effect of PL in lung cancer cells still remains unclear. In the present study, we reported the chemotherapeutic effects of PL using in vitro and in vivo models. We showed that PL displayed potent anti-neoplastic activity against lung cancer A549 cells as well as corresponding docetaxel-resistant A549/DTX cells. In addition, we found that PL induced apoptosis in both A549 and A549/DTX cells. PL also induced autophagy in A549/DTX cells. Moreover, autophagy-specific inhibitors (3-methyladenine) or Beclin1 and Atg 5 small interfering RNAs (siRNAs) enhanced PL-induced apoptosis, indicating that PL-mediated autophagy may protect A549/DTX cells from undergoing apoptotic cell death. Furthermore, we observed the inhibition of phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway by PL. Finally, PL inhibited the growth of A549/DTX xenograft tumors, which was associated with inhibition of cell proliferation, induction of apoptosis of tumor cells and decreased expression of p-Akt and p-mTOR in tumor xenograft tissues. In summary, our study demonstrated that PL induced apoptosis and autophagy through modulation of the PI3K/Akt/mTOR pathway in human lung cancer cells. This study may provide a rationale for future clinical application using PL as a chemotherapeutic agent for lung cancer.

Wang F ，Mao Y ，You Q ，Hua D ，Cai D ... -  《INTERNATIONAL JOURNAL OF IMMUNOPATHOLOGY AND PHARMACOLOGY》

Arenobufagin, a natural bufadienolide from toad venom, induces apoptosis and autophagy in human hepatocellular carcinoma cells through inhibition of PI3K/Akt/mTOR pathway.

Zhang DM ，Liu JS ，Deng LJ ，Chen MF ，Yiu A ，Cao HH ，Tian HY ，Fung KP ，Kurihara H ，Pan JX ，Ye WC ... -  《-》

Antitumor activity of curcumin by modulation of apoptosis and autophagy in human lung cancer A549 cells through inhibiting PI3K/Akt/mTOR pathway.

Liu F ，Gao S ，Yang Y ，Zhao X ，Fan Y ，Ma W ，Yang D ，Yang A ，Yu Y ... -  《-》

Licochalcone A induces autophagy through PI3K/Akt/mTOR inactivation and autophagy suppression enhances Licochalcone A-induced apoptosis of human cervical cancer cells.

Tsai JP ，Lee CH ，Ying TH ，Lin CL ，Lin CL ，Hsueh JT ，Hsieh YH ... -  《Oncotarget》

Piperlongumine, a piper alkaloid targets Ras/PI3K/Akt/mTOR signaling axis to inhibit tumor cell growth and proliferation in DMH/DSS induced experimental colon cancer.

Colorectal cancer (CRC) is the most common carcinoma of the digestive tract. The slow growing nature of CRC offers a great opportunity for prevention strategies. The concept of chemoprevention of colorectal cancer using plant derived natural products is gaining substantial attention because it is an inherently safe and cost-effective alternative to conventional cancer therapies. Piperlongumine (PL), a natural alkaloid present in Piper longum Linn has been reported to exhibit notable anticancer effects in various in vitro studies. Nonetheless, the chemopreventive potential of PL has not been studied in experimentally induced colon cancer yet. Ras/PI3K/Akt/mTOR signaling axis plays a central role in promoting tumor cell growth, proliferation and survival by inhibiting apoptosis. In the present study, we demonstrated, for the first time, the chemopreventive effects of PL in DMH + DSS induced colon carcinogenesis animal model. We showed that PL displayed potent antineoplastic activity against colon cancer cell growth by targeting Ras proteins and PI3K/Akt signaling cascade. PL mediated inhibition of tumor cell growth was associated with inhibition of Ras protein levels and its preferred companion protein PI3K levels that led to suppressed activity of Akt/NF-κB, c-Myc and cyclin D1. It was also found that PL arrested the cell cycle progression at G2/M phase and induced mitochondrial apoptotic pathway by downregulating Bcl-2 levels. Furthermore, the results of liver and kidney toxicity suggested that PL exhibit no toxicity in animals. Our results suggest that PL may be an effective chemopreventive agent for colon cancer.

Kumar S ，Agnihotri N 《-》