bafilomycin-a1 and Carcinoma--Squamous-Cell

The role of autophagy in tongue squamous cell carcinoma (TSCC) cisplatin resistance is unclear. We aimed to identify a possible synergistic effect of autophagy inhibitors and cisplatin in TSCC cells and explore the underlying mechanism. Our results indicate that autophagic flux was high in TSCC cells; Autophagy inhibitor bafilomycin A1 increased cisplatin cytotoxicity in TSCC cells by inhibiting lysosomal uptake of platinum and enhancing intracellular platinum ion binding to DNA; Autophagy gene (Atg5) knockout in TSCC cells did not duplicate the above-mentioned sensitization of bafilomycin A1. Furthermore, we found that cisplatin resistance of TSCC cells was related to cisplatin inducing lysosome biogenesis in a TFEB-dependent manner, which was regulated by c-Abl. In summary, this is the first study to show that Bafilomycin A1 increases the sensitivity of TSCC cells to cisplatin by inhibiting lysosomal function but not autophagy. Lysosomes may be a potential target to increase cisplatin cytotoxicity toward TSCC cells.

Topics: Autophagy; Autophagy-Related Protein 5; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Carcinoma, Squamous Cell; Cell Line, Tumor; Cisplatin; Drug Resistance, Neoplasm; Drug Synergism; Gene Expression Regulation, Neoplastic; Gene Knockout Techniques; Humans; Lysosomes; Macrolides; Platinum; Proto-Oncogene Proteins c-abl; Tongue Neoplasms

Thymoquinone (TQ), an active component of Nigella sativa or black cumin, elicits cytotoxic effects on various cancer cell lines. However, the anti-cancer effects of TQ on head and neck squamous cell carcinoma (HNSCC) remain unclear.. In this study, TQ elicited a strong cytotoxic effect on SASVO3, a highly malignant HNSCC cell line. The mechanisms of this cytotoxic effect were concentration dependent. TQ also induced apoptotic cell death in SASVO3 cells as indicated by an increase in Bax expression and caspase-9 activation. Apoptosis was possibly caspase-9 dependent because the exposure of cells to a caspase-9 inhibitor partially prevented cell death. The exposed cells also showed increased levels of autophagic vacuoles and LC3-II proteins, which are specific autophagy markers. Cell viability assay results further revealed that bafilomycin-A1, an autophagy inhibitor, enhanced TQ cytotoxicity; by comparison, Annexin V and propidium-iodide staining assay results showed that this inhibitor did not promote apoptosis. TQ treatment also increased the accumulation of autophagosomes. Using a lentivirus-shRNA system for LC3 silencing, we found that cell viability was eradicated in autophagy-defective cells. An in vivo BALB/c nude mouse xenograft model further showed that TQ administered by oral gavage reduced tumor growth via induced autophagy and apoptosis.. These findings indicated that TQ induced cell death in oral cancer cells via two distinct anti-neoplastic activities that can induce apoptosis and autophagy. Therefore, TQ is a promising candidate in phytochemical-based, mechanistic, and pathway-targeted cancer prevention strategies.

Topics: Animals; Antineoplastic Agents; Apoptosis; Autophagy; Benzoquinones; Carcinoma, Squamous Cell; Caspases; Cell Line, Tumor; Cell Survival; Drug Synergism; Enzyme Activation; Head and Neck Neoplasms; Humans; Macrolides; Mice; Microtubule-Associated Proteins; Phagosomes; Squamous Cell Carcinoma of Head and Neck; Xenograft Model Antitumor Assays

Numerous studies have demonstrated that autophagy is associated with cancer development. Thus, agents to induce autophagy could be employed in some cases for the treatment of cancer. Our results showed that tetrandrine significantly decreased the viability of SAS cells in a concentration- and time-dependent manner. Tetrandrine induced nuclear condensation, demonstrated by DAPI staining. The early events in apoptosis analysed by Annexin V/PI staining indicated that the percentage of cells staining positive for Annexin V was slightly increased in SAS cells with tetrandrine treatment but was much lower following bafilomycin A1 pre-treatment. Tetrandrine caused AVO and MDC induction in SAS cells in a concentration-dependent manner by fluorescence microscopy. Tetrandrine also caused LC-3 expression in SAS cells in a time-dependent manner. Our results show that tetrandrine treatment induced the levels of cleaved caspase-3 in a concentration- and time-dependent manner. Tetrandrine treatment induced the levels of LC-3 II, Atg-5, beclin-1, p-S6, p-ULK, p-mTOR, p-Akt (S473) and raptor. Tetrandrine decreased cell viability, but bafilomycin A1, 3-MA, chloroquine and NAC protected tetrandrine-treated SAS cells against decrease of cell viability. Atg-5, beclin-1 siRNA decreased tetrandrine-induced cleaved caspase-3 and cleaved PARP in SAS cells and protected tetrandrine-treated SAS cells against decrease in cell viability. Chloroquine, NAC and bafilomycin A1 also decreased tetrandrine-induced cleaved caspase-3 and cleaved PARP in SAS cells. Our results indicate the tetrandrine induces apoptosis and autophagy of SAS human cancer cells via caspase-dependent and LC3-I and LC3-II‑dependent pathways.

Topics: Antineoplastic Agents, Phytogenic; Antirheumatic Agents; Apoptosis; Apoptosis Regulatory Proteins; Autophagy; Autophagy-Related Protein-1 Homolog; Beclin-1; Benzylisoquinolines; Carcinoma, Squamous Cell; Caspase 3; Cell Line, Tumor; Cell Survival; Chloroquine; Enzyme Inhibitors; Humans; Intracellular Signaling Peptides and Proteins; Macrolides; Membrane Proteins; Microtubule-Associated Proteins; Mouth Neoplasms; Poly(ADP-ribose) Polymerases; Protein Serine-Threonine Kinases; RNA Interference; RNA, Small Interfering