title: Inhibition of autophagy augments apoptosis in human oral squamous cell carcinoma under nutrient depletion.
abstract: There has been little research conducted regarding autophagy in oral squamous cell carcinoma (OSCC). Given the prevalence of oral cancers which are OSCC and the severe side effects of current treatments, there is a pressing need to develop effective alternative therapies. In this study, we have endeavored to explore the biological characteristics of oral squamous cell carcinoma cell line KB cells, in particular with regard to the role played by autophagy in their survival. Autophagy was activated by nutrient depletion via culturing cells in Earle's balanced salts (EBSS) and was measured via indices relating to Beclin 1, microtubule-associated protein light chain 3 (MAPLC3, LC3), p62, and Green fluorescent protein-light chain 3 plasmid transfection (GFP-LC3). Cell death and apoptosis induced by nutrient depletion was measured using both MTT assay and flow cytometry (FCM). Compared to initial levels at 0 h, Beclin 1 density in EBSS-treated cells was found to have increased at 6, 12, and 18 h in a time-dependent manner and was found to have subsequently declined at 24 and 48 h. p62 levels, LC3-II/LC3-I ratio, and GFP-LC3 levels increased at 6, 12, 18, 24, and 48 h in a time-dependent manner. 3-methyladenine (3-MA) was found to inhibit autophagy and the expression of Beclin 1 and significantly enhanced nutrient depletion-induced apoptosis and death. We concluded that nutrient depletion enhances OSCC cell autophagy in time-course patterns and that the inhibition of autophagy augments apoptosis in OSCC cells. We also deduced that Beclin 1 takes part in the development and progression of autophagy, potentially playing an important role in the crosstalk between apoptosis and autophagy in OSCC cells. These findings suggest that nutrient depletion may be an effective way to explore autophagy and that autophagy inhibitors should be investigated as a potential novel agent for the adjuvant treatment of human OSCC.
authors.affiliation: Shandong Province Key Laboratory of Oral and Maxillofacial-Head and Neck Medicine (SPKLOMHNM), Zhong Yuan Academy of Biological Medicine, Liaocheng University, and Liaocheng People's Hospital, Medical School of Liaocheng, Taishan Medical University, Liaocheng, Shandong, China.
authors.forename: Li-Cheng
authors.initials: LC
authors.lastname: Jiang
authors.forename: Zhi-Yuan
authors.initials: ZY
authors.lastname: Xin
authors.forename: Baremberg
authors.initials: B
authors.lastname: Deborah
authors.forename: Jun-Sheng
authors.initials: JS
authors.lastname: Zhang
authors.forename: Dao-Ying
authors.initials: DY
authors.lastname: Yuan
authors.forename: Kai
authors.initials: K
authors.lastname: Xu
authors.forename: Xian-Bin
authors.initials: XB
authors.lastname: Liu
authors.forename: Hu-Quan
authors.initials: HQ
authors.lastname: Jiang
authors.forename: Qing-Chun
authors.initials: QC
authors.lastname: Fan
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.forename: Ke-Yi
authors.initials: KY
authors.lastname: Li
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy / Q000502:physiology; D000071186:Beclin-1; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D007624:KB Cells; D008565:Membrane Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics; D009062:Mouth Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D011994:Recombinant Proteins / Q000235:genetics; D014162:Transfection
chemical_list: D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; C477012:MAP1LC3A protein, human; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; C025946:3-methyladenine; D000225:Adenine
keywords: Beclin 1; apoptosis; autophagy; nutrient depletion; oral squamous cell carcinoma