title: Defective autophagosome formation in p53-null colorectal cancer reinforces crocin-induced apoptosis.
abstract: Crocin, a bioactive molecule of saffron, inhibited proliferation of both HCT116 wild-type and HCT116 p53(-/-) cell lines at a concentration of 10 mM. Flow cytometric analysis of cell cycle distribution revealed that there was an accumulation of HCT116 wild-type cells in G1 (55.9%, 56.1%) compared to the control (30.4%) after 24 and 48 h of crocin treatment, respectively. However, crocin induced only mild G2 arrest in HCT116 p53(-/-) after 24 h. Crocin induced inefficient autophagy in HCT116 p53(-/-) cells, where crocin induced the formation of LC3-II, which was combined with a decrease in the protein levels of Beclin 1 and Atg7 and no clear p62 degradation. Autophagosome formation was not detected in HCT116 p53(-/-) after crocin treatment predicting a nonfunctional autophagosome formation. There was a significant increase of p62 after treating the cells with Bafilomycin A1 (Baf) and crocin compared to crocin exposure alone. Annexin V staining showed that Baf-pretreatment enhanced the induction of apoptosis in HCT116 wild-type cells. Baf-exposed HCT116 p53(-/-) cells did not, however, show any enhancement of apoptosis induction despite an increase in the DNA damage-sensor accumulation, γH2AX indicating that crocin induced an autophagy-independent classical programmed cell death.
authors.affiliation: Department of Biology, College of Science, United Arab Emirates University, Al-Ain 15551, United Arab Emirates. a.amin@uaeu.ac.ae.
authors.forename: Amr
authors.initials: A
authors.lastname: Amin
authors.affiliation: Department of Biology, College of Science, United Arab Emirates University, Al-Ain 15551, United Arab Emirates. khuloud@hotmail.de.
authors.forename: Khuloud
authors.initials: K
authors.lastname: Bajbouj
authors.affiliation: Experimental Tumor Pathology, Institute of Pathology, University of Erlangen, Erlangen 91054, Germany. adrian.koch@uk-erlangen.de.
authors.forename: Adrian
authors.initials: A
authors.lastname: Koch
authors.affiliation: Experimental Tumor Pathology, Institute of Pathology, University of Erlangen, Erlangen 91054, Germany. mukthi_14@yahoo.com.
authors.forename: Muktheshwar
authors.initials: M
authors.lastname: Gandesiri
authors.affiliation: Experimental Tumor Pathology, Institute of Pathology, University of Erlangen, Erlangen 91054, Germany. regine.schneider-stock@uk-erlangen.de.
authors.forename: Regine
authors.initials: R
authors.lastname: Schneider-Stock
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects; D000071193:Autophagy-Related Protein 7; D000071186:Beclin-1; D002338:Carotenoids / Q000633:toxicity*; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000473:pathology; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects; D045325:HCT116 Cells; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D044764:Ubiquitin-Activating Enzymes / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; C477012:MAP1LC3A protein, human; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; C118585:P62 protein, human; D016601:RNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; D002338:Carotenoids; C029036:crocin; C509349:ATG7 protein, human; D000071193:Autophagy-Related Protein 7; D044764:Ubiquitin-Activating Enzymes