title: Andrographolide Analogue Induces Apoptosis and Autophagy Mediated Cell Death in U937 Cells by Inhibition of PI3K/Akt/mTOR Pathway.
abstract: BACKGROUND
  Current chemotherapeutic agents based on apoptosis induction are lacking in desired efficacy. Therefore, there is continuous effort to bring about new dimension in control and gradual eradication of cancer by means of ever evolving therapeutic strategies. Various forms of PCD are being increasingly implicated in anti-cancer therapy and the complex interplay among them is vital for the ultimate fate of proliferating cells. We elaborated and illustrated the underlying mechanism of the most potent Andrographolide analogue (AG-4) mediated action that involved the induction of dual modes of cell death-apoptosis and autophagy in human leukemic U937 cells.
  
  
  RESULTS
  AG-4 induced cytotoxicity was associated with redox imbalance and apoptosis which involved mitochondrial depolarisation, altered apoptotic protein expressions, activation of the caspase cascade leading to cell cycle arrest. Incubation with caspase inhibitor Z-VAD-fmk or Bax siRNA decreased cytotoxic efficacy of AG-4 emphasising critical roles of caspase and Bax. In addition, AG-4 induced autophagy as evident from LC3-II accumulation, increased Atg protein expressions and autophagosome formation. Pre-treatment with 3-MA or Atg 5 siRNA suppressed the cytotoxic effect of AG-4 implying the pro-death role of autophagy. Furthermore, incubation with Z-VAD-fmk or Bax siRNA subdued AG-4 induced autophagy and pre-treatment with 3-MA or Atg 5 siRNA curbed AG-4 induced apoptosis-implying that apoptosis and autophagy acted as partners in the context of AG-4 mediated action. AG-4 also inhibited PI3K/Akt/mTOR pathway. Inhibition of mTOR or Akt augmented AG-4 induced apoptosis and autophagy signifying its crucial role in its mechanism of action.
  
  
  CONCLUSIONS
  Thus, these findings prove the dual ability of AG-4 to induce apoptosis and autophagy which provide a new perspective to it as a potential molecule targeting PCD for future cancer therapeutics.
authors.affiliation: Cancer Biology and Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata 700 032, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Kumar
authors.affiliation: Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata 700 032, India.
authors.forename: Bimolendu
authors.initials: B
authors.lastname: Das
authors.affiliation: Department of Pharmacology, Institute of Post Graduate Medical Education and Research, 244B, A.J.C. Bose Road, Kolkata 700 020, India.
authors.forename: Rupashree
authors.initials: R
authors.lastname: Sen
authors.affiliation: Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata 700 032, India.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Kundu
authors.affiliation: Department of Pharmacology, Institute of Post Graduate Medical Education and Research, 244B, A.J.C. Bose Road, Kolkata 700 020, India.
authors.forename: Alak
authors.initials: A
authors.lastname: Manna
authors.affiliation: Department of Pharmacology, Institute of Post Graduate Medical Education and Research, 244B, A.J.C. Bose Road, Kolkata 700 020, India.
authors.forename: Avijit
authors.initials: A
authors.lastname: Sarkar
authors.affiliation: Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata 700 032, India.
authors.forename: Chinmay
authors.initials: C
authors.lastname: Chowdhury
authors.affiliation: Department of Pharmacology, Institute of Post Graduate Medical Education and Research, 244B, A.J.C. Bose Road, Kolkata 700 020, India.
authors.forename: Mitali
authors.initials: M
authors.lastname: Chatterjee
authors.affiliation: Cancer Biology and Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata 700 032, India.
authors.forename: Padma
authors.initials: P
authors.lastname: Das
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D004224:Diterpenes / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors*; D034741:RNA, Small Interfering / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors*; D020298:U937 Cells / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D004224:Diterpenes; D009363:Neoplasm Proteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D034741:RNA, Small Interfering; C000608221:andrographolide-4; C546842:MTOR protein, human; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D020169:Caspases; D015107:4-Butyrolactone