Piperlongumine, an alkaloid causes inhibition of PI3 K/Akt/mTOR signaling axis to induce caspase-dependent apoptosis in human triple-negative breast cancer cells

• Published in: Apoptosis (London) 2014-07, Vol.19 (7), p.1148-1164
• Main Authors: Shrivastava, Shweta, Kulkarni, Prasad, Thummuri, Dinesh, Jeengar, Manish Kumar, Naidu, V. G. M., Alvala, Mallika, Redddy, G. Bhanuprakash, Ramakrishna, Sistla
• Format: Article
• Language: English
• Subjects: Alkaloids - pharmacology; Apoptosis - drug effects; Biochemistry; Biomedical and Life Sciences; Biomedicine; Breast cancer; Cancer Research; Caspases - metabolism; Cell Biology; Cell Cycle Checkpoints - drug effects; Cell Cycle Checkpoints - genetics; Cell Line, Tumor; Cell Proliferation - drug effects; Dioxolanes - pharmacology; DNA Fragmentation - drug effects; Female; Humans; Insulin; Molecular Docking Simulation; Oncology; Original Paper; Phosphatidylinositol 3-Kinase - metabolism; Proto-Oncogene Proteins c-akt - metabolism; Reactive Oxygen Species - metabolism; Signal Transduction; TOR Serine-Threonine Kinases - metabolism; Triple Negative Breast Neoplasms - metabolism; Triple Negative Breast Neoplasms - pathology; Virology
• ISSN: 1360-8185; 1573-675X
• DOI: 10.1007/s10495-014-0991-2

The phosphatidylinositol 3-kinase (PI3 K)/Akt/mammalian target of rapamycin (mTOR) signaling axis plays a central role in cell proliferation, growth and survival under physiological conditions. However, aberrant PI3 K/Akt/mTOR signaling has been implicated in many human cancers, including human triple negative breast cancer. Therefore, dual inhibitors of PI3 K/Akt and mTOR signaling could be valuable agents for treating breast cancer. The objective of this study was to investigate the effect of piperlongumine (PPLGM), a natural alkaloid on PI3 K/Akt/mTOR signaling, Akt mediated regulation of NF-kB and apoptosis evasion in human breast cancer cells. Using molecular docking studies, we found that PPLGM physically interacts with the conserved domain of PI3 K and mTOR kinases and the results were comparable with standard dual inhibitor PF04691502. Our results demonstrated that treatment of different human triple-negative breast cancer cells with PPLGM resulted in concentration- and time-dependent growth inhibition. The inhibition of cancer cell growth was associated with G1-phase cell cycle arrest and down-regulation of the NF-kB pathway leads to activation of the mitochondrial apoptotic pathway. It was also found that PPLGM significantly decreased the expression of p-Akt, p70S6K1, 4E-BP1, cyclin D1, Bcl-2, p53 and increased expression of Bax, cytochrome c in human triple-negative breast cancer cells. Although insulin treatment increased the phosphorylation of Akt (Ser473), p70S6K1, 4E-BP1, PPLGM abolished the insulin mediated phosphorylation, it clearly indicates that PPLGM acts through PI3 k/Akt/mTOR axis. Our results suggest that PPLGM may be an effective therapeutic agent for the treatment of human triple negative breast cancer.