Induction of Non-Apoptotic Cell Death by Adrenergic Agonists in Human Oral Squamous Cell Carcinoma Cell Lines.

BACKGROUND/AIM: Although adrenergic agonists have been used in dental treatments and oral surgery for general anesthesia, their cytotoxicity against human oral malignant and non-malignant cell has not been well- understood. The present study was undertaken to investigate the cytotoxicity of five adrenergic agonists against human oral squamous cell carcinoma (OSCC), glioblastoma, promyelocytic leukemia, and normal oral mesenchymal cells (gingival fibroblast, pulp cell, periodontal ligament fibroblast) and normal epidermal keratinocytes. MATERIALS AND METHODS: Tumor-specificity (TS) was calculated by the ratio between the mean 50% cytotoxic concentration against normal cells to that of tumor cells. Internucleosomal DNA fragmentation was detected using agarose gel electrophoresis. Caspase-3 activity was measured by substrate cleavage. RESULTS: Both cytotoxicity and tumor-specificity of adrenergic agonists against OSCC cell lines was in the order of isoprenaline>dexmedetomidine> adrenaline>clonidine and phenylephrine. Isoprenaline and dexmedetomidine did not induce apoptosis markers, such as internucleosomal DNA fragmentation and caspase-3 activation, but induced a smear pattern of DNA fragmentation in OSCC cell lines. Their cytotoxicity was not reduced by pretreatment with autophagy inhibitors, or by adrenoceptors antagonists. Addition of superoxide dismutase and catalase significantly reduced the cytotoxicity of isoprenaline, but not that of dexmedetomidine. CONCLUSION: Isoprenaline and dexmedetomidine induce non-apoptotic cell death by different mechanisms.

Developmental YAPdeltaC determines adult pathology in a model of spinocerebellar ataxia type 1.

YAP and its neuronal isoform YAPdeltaC are implicated in various cellular functions. We found that expression of YAPdeltaC during development, but not adulthood, rescued neurodegeneration phenotypes of mutant ataxin-1 knock-in (Atxn1-KI) mice. YAP/YAPdeltaC interacted with RORα via the second WW domain and served as co-activators of its transcriptional activity. YAP/YAPdeltaC formed a transcriptional complex with RORα on cis-elements of target genes and regulated their expression. Both normal and mutant Atxn1 interacted with YAP/YAPdeltaC, but only mutant Atxn1 depleted YAP/YAPdeltaC from the RORα complex to suppress transcription on short timescales. Over longer periods, mutant Atxn1 also decreased RORα in vivo. Genetic supplementation of YAPdeltaC restored the RORα and YAP/YAPdeltaC levels, recovered YAP/YAPdeltaC in the RORα complex and normalized target gene transcription in Atxn1-KI mice in vivo. Collectively, our data suggest that functional impairment of YAP/YAPdeltaC by mutant Atxn1 during development determines the adult pathology of SCA1 by suppressing RORα-mediated transcription.

Cytotoxicity and type of cell death induced by midazolam in human oral normal and tumor cells.

BACKGROUND: Intravenous anesthetics have been used during the treatment of various malignant tumors, however, their effects on oral tissues is not well-understood. In the present study, the cytotoxicity of five intravenous anesthetics towards oral tumor and normal cells was compared. MATERIALS AND METHODS: Tumor specificity index was determined by the ratio of the mean 50% cytotoxic concentration for normal cells to that for tumor cells. Apoptosis induction was monitored by internucleosomal DNA fragmentation and caspase-3, -8, and -9 activation. Fine cell structure was observed under transmission electron microscopy. RESULTS: Benzodiazepines (midazolam and diazepam) exhibited higher cytotoxicity than barbiturates (thiopental and thiamylal), whereas propofol had the intermediate range of cytotoxicity. Midazolam showed the highest cytotoxicity. HL-60 cells were the most sensitive to midazolam, followed by epidermal keratinocytes, oral squamous cell carcinoma (OSCC), glioblastoma and then oral normal cells. Midazolam did not induce the production of apoptosis markers such as internucleosomal DNA fragmentation and activation of caspase-3, -8 and -9, but did induce the appearance of many vacuoles, mitochondrial swelling and cell membrane rupture in OSCC cell lines (HSC-2 and HSC-4) cells. The cytotoxicity of midazolam was not reduced by pre-treatment with autophagy inhibitors (3-methyladenine and bafilomycin A1). CONCLUSION: These results suggest that midazolam may induce necrotic cell death, rather than apoptosis or autophagy, in OSCC cell lines.

Cytotoxicity and type of cell death induced by local anesthetics in human oral normal and tumor cells.

BACKGROUND: Local anesthetics are often administered to tumors and surrounding tissues during the surgery of the head and neck area, however their effects on oral tissues is not well understood. In the present study, the cytotoxicity of a total of seven local anesthetics towards oral tumor and normal cells was compared. MATERIALS AND METHODS: Tumor-specificity index was determined by the ratio of the mean 50% cytotoxic concentration against normal cells to that for tumor cells. Apoptosis induction was monitored by internucleosomal DNA fragmentation and caspase-3, -8, and - 9 activation. Fine cell structure was observed under transmission electron microscopy. RESULTS: All local anesthetics showed slightly higher cytotoxicity towards oral squamous cell carcinoma (OSCC) cell lines than towards normal oral cells. Dibucaine, with a log p-value of approximately 3, was the most cytotoxic, followed by tetracaine, bupivacaine or ethylaminobenzoate, whereas lidocaine, procaine and mepivacain were much less cytotoxic. When the tumor-specificity was evaluated between OSCC and human skin keratinocytes, the index was 6.6. Dibucaine did not induce apoptosis of OSCC cells. On the other hand, dibucaine did induce mitochondrial injury and swelling, formation of secondary lysosomes, and at high concentrations, rupture of the cell membrane. Autophagy inhibitors did not reduce the cytotoxicity of dibucaine. CONCLUSION: Necrosis may be involved in the induction of antitumor activity by dibucaine.