title: CDKN2A-p53 mediated antitumor effect of Lupeol in head and neck cancer.
abstract: OBJECTIVE
  The tumor suppressor protein p53 is known to control cell cycle arrest and apoptosis. Lupeol is a phytochemical that has been found to induce apoptosis in different cancer types through the extrinsic pathway. As yet, however, its role in the induction of cell cycle arrest and apoptosis through the intrinsic pathway in head and neck cancer has not been investigated. Here, we aimed at understanding the mechanism underlying the antitumor effect of Lupeol in head and neck cancer.
  
  
  METHODS
  The antitumor effect of Lupeol on oral and laryngeal carcinomas was assessed using two in vitro 2D cell line models (HEp-2, UPCI:SCC-131) and, subsequently, an ex vivo 3D tumor explant culture platform that maintains key features of the native tumor microenvironment. The mechanism underlying Lupeol-mediated antitumor responses was delineated using MTT, colony formation, flow cytometry, immunofluorescence, Western blotting and immunohistochemistry assays.
  
  
  RESULTS
  We found that Lupeol induced an enhanced expression of p53 in both cell line models tested and, subsequently, cell cycle arrest at the G1 phase. In addition we found that, following Lupeol treatment, p53 induced Bax expression and activated the intrinsic apoptotic pathway (as measured by Caspase-3 cleavage). Interestingly, Lupeol was also found to trigger G1 cell cycle arrest through up-regulation of the expression of CDKN2A, but not p21, resulting in inhibition of CyclinD1. In an ex vivo platform Lupeol was found to impart a potent antitumor response as defined by inhibition of Ki67 expression, decreased cell viability and concomitant activation (cleavage) of Caspase-3. Finally, we found that Lupeol can re-sensitize primary head and neck squamous cell carcinoma (HNSCC) tumor samples that had clinically progressed under a Cisplatin treatment regimen.
  
  
  CONCLUSIONS
  Together, our data indicate that Lupeol may orchestrate a bifurcated regulation of neoplastic growth and apoptosis in head and neck cancers and may serve as a promising agent for the management of tumors that have progressed on a platinum-based treatment regimen.
authors.affiliation: Department of Signal Transduction and Biogenic Amines, Chittaranjan National Cancer Institute, 37, S. P. Mukherjee Road, Kolkata, 700026, India.
authors.forename: Sayantan
authors.initials: S
authors.lastname: Bhattacharyya
authors.affiliation: Department of Molecular Pathology and Cancer Biology, Mitra Biotech, 202, Narayana Nethralaya, Hosur Main Road, Bangalore, 560099, India.
authors.forename: Vasanthakumar
authors.initials: V
authors.lastname: Sekar
authors.affiliation: Department of Molecular Pathology and Cancer Biology, Mitra Biotech, 202, Narayana Nethralaya, Hosur Main Road, Bangalore, 560099, India.
authors.forename: Biswanath
authors.initials: B
authors.lastname: Majumder
authors.affiliation: Department of Molecular Pathology and Cancer Biology, Mitra Biotech, 202, Narayana Nethralaya, Hosur Main Road, Bangalore, 560099, India.
authors.forename: Debapriya G
authors.initials: DG
authors.lastname: Mehrotra
authors.affiliation: Department of Signal Transduction and Biogenic Amines, Chittaranjan National Cancer Institute, 37, S. P. Mukherjee Road, Kolkata, 700026, India.
authors.forename: Samir
authors.initials: S
authors.lastname: Banerjee
authors.affiliation: Department of ENT, Chittaranjan National Cancer Institute, 37, S. P. Mukherjee Road, Kolkata, 700026, India.
authors.forename: Anup K
authors.initials: AK
authors.lastname: Bhowmick
authors.affiliation: Department of Surgical Oncology, Chittaranjan National Cancer Institute, 37, S. P. Mukherjee Road, Kolkata, 700026, India.
authors.forename: Neyaz
authors.initials: N
authors.lastname: Alam
authors.affiliation: Department of Pathology, Chittaranjan National Cancer Institute, 37, S. P. Mukherjee Road, Kolkata, 700026, India.
authors.forename: Gautam K
authors.initials: GK
authors.lastname: Mandal
authors.affiliation: Department of Translation Research, Chittaranjan National Cancer Institute, 37, S. P. Mukherjee Road, Kolkata, 700026, India.
authors.forename: Jaydip
authors.initials: J
authors.lastname: Biswas
authors.affiliation: Mitra Biotech, 12, Gill Street, Suite, Woburn, MA, 3150, USA.
authors.forename: Pradip K
authors.initials: PK
authors.lastname: Majumder
authors.affiliation: Department of Signal Transduction and Biogenic Amines, Chittaranjan National Cancer Institute, 37, S. P. Mukherjee Road, Kolkata, 700026, India. nabendu.murmu@cnci.org.in.
authors.forename: Nabendu
authors.initials: N
authors.lastname: Murmu
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism*; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects; D006258:Head and Neck Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D053978:Pentacyclic Triterpenes / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D000094042:Lupanes
chemical_list: D000970:Antineoplastic Agents; D019941:Cyclin-Dependent Kinase Inhibitor p16; D053978:Pentacyclic Triterpenes; D016159:Tumor Suppressor Protein p53; C010480:lupeol; D000094042:Lupanes
keywords: Apoptosis; Cell cycle arrest; Head and neck cancer; Lupeol; p53