title: Cryptolepine, a Plant Alkaloid, Inhibits the Growth of Non-Melanoma Skin Cancer Cells through Inhibition of Topoisomerase and Induction of DNA Damage.
abstract: Topoisomerases have been shown to have roles in cancer progression. Here, we have examined the effect of cryptolepine, a plant alkaloid, on the growth of human non-melanoma skin cancer cells (NMSCC) and underlying mechanism of action. For this purpose SCC-13 and A431 cell lines were used as an in vitro model. Our study reveals that SCC-13 and A431 cells express higher levels as well as activity of topoisomerase (Topo I and Topo II) compared with normal human epidermal keratinocytes. Treatment of NMSCC with cryptolepine (2.5, 5.0 and 7.5 µM) for 24 h resulted in marked decrease in topoisomerase activity, which was associated with substantial DNA damage as detected by the comet assay. Cryptolepine induced DNA damage resulted in: (i) an increase in the phosphorylation of ATM/ATR, BRCA1, Chk1/Chk2 and γH2AX; (ii) activation of p53 signaling cascade, including enhanced protein expressions of p16 and p21; (iii) downregulation of cyclin-dependent kinases, cyclin D1, cyclin A, cyclin E and proteins involved in cell division (e.g., Cdc25a and Cdc25b) leading to cell cycle arrest at S-phase; and (iv) mitochondrial membrane potential was disrupted and cytochrome c released. These changes in NMSCC by cryptolepine resulted in significant reduction in cell viability, colony formation and increase in apoptotic cell death.
authors.affiliation: Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294, USA. hcpal@uab.edu.
authors.forename: Harish C
authors.initials: HC
authors.lastname: Pal
authors.affiliation: Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294, USA. skatiyar@uab.edu.|Environmental Health Sciences, University of Alabama at Birmingham, Birmingham, AL 35294, USA. skatiyar@uab.edu.|Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA. skatiyar@uab.edu.|Birmingham Veterans Affairs Medical Center, Birmingham, AL 35294, USA. skatiyar@uab.edu.
authors.forename: Santosh K
authors.initials: SK
authors.lastname: Katiyar
mesh_terms: D000470:Alkaloids / Q000494:pharmacology*; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D019313:BRCA1 Protein / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1 / Q000235:genetics / Q000378:metabolism; D064447:Checkpoint Kinase 2 / Q000235:genetics / Q000378:metabolism; D020552:Comet Assay; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D004264:DNA Topoisomerases, Type I / Q000235:genetics* / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D026121:Indole Alkaloids / Q000494:pharmacology*; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009928:Organ Specificity; D011804:Quinolines / Q000494:pharmacology*; D015398:Signal Transduction; D059003:Topoisomerase Inhibitors / Q000494:pharmacology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: C522841:ATMIN protein, human; D000470:Alkaloids; D000972:Antineoplastic Agents, Phytogenic; D019313:BRCA1 Protein; C492913:BRCA1 protein, human; C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; C468783:H2AX protein, human; D006657:Histones; D026121:Indole Alkaloids; D011804:Quinolines; D059003:Topoisomerase Inhibitors; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; C024015:cryptolepine; D064447:Checkpoint Kinase 2; C000605867:CHEK1 protein, human; C578634:CHEK2 protein, human; D000071877:Checkpoint Kinase 1; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II
keywords: DNA damage; apoptosis; cell cycle; cryptolepine; skin cancer; topoisomerase