TFEB and TFE3 cooperate in regulating inorganic arsenic-induced autophagy-lysosome impairment and immuno-dysfunction in primary dendritic cells.

Arsenic (As) is a prevalent and hazardous environmental toxicant associated with cancer and various health problems, which has been shown suppressive effects on dendritic cells (DCs). Autophagy is essential for the innate and adaptive immune responses of DCs, and the transcription factors TFEB and TFE3 are key regulators of autophagic and lysosomal target genes. However, the detrimental alterations of the autophagy-lysosome pathway in As-exposed DCs and the possible coordinating roles of TFEB and TFE3 in the immune dysfunction of this cell are less understood. In this paper, we found that As exposure significantly impaired lysosomal number, lysosomal acidic environment, and lysosomal membrane permeabilization, which might lead to blocked autophagic flux in cultured DCs. Furthermore, our results confirmed that TFEB or TFE3 knockdown exacerbated the disorders of lysosome and the blockade of autophagic flux in As-exposed DCs, and also enhanced the inhibitory expression of co-stimulatory molecules Cd80 and Cd83; adhesion molecule Icam1; cytokines TNF-α, IL-1ß, and IL-6; chemokine receptor Ccr7; and antigen-presenting molecules MHC II and MHC I. By contrast, overexpression of TFEB or TFE3 partially alleviated the above-mentioned impairment of DCs by inorganic As exposure. In conclusion, these findings reveal a previously unappreciated inhibition of lysosome-mediated degradation and damage of lysosomal membrane integrity leading to dysregulated autophagy and impaired immune functions of DCs by arsenicals, and also suggest TFEB and TFE3 as potential therapeutic targets for ameliorating As toxicity.

[Expression and significance of signal transducer and activator of transcription 3 and c-myc in laryngeal squamous cell carcinoma].

OBJECTIVE: To investigate the expression and clinical significance of signal transducer and activator of transcription 3(STAT3) and its target gene c-myc in laryngeal squamous cell carcinoma (LSCC), and the relationship between the two genes. METHOD: Formalin-fixed and paraffin-embedded tissues, which came from 56 cases of LSCC and 30 samples of normal mucosas from 30 patients with total or subtotal laryngectomy over 2.0 cm away from tumor margin, were detected for the expression of STATS, c-myc by in situ hybridization and SP immunohistochemistry. Micro-image analysis system was used to determine the optical density, and the result was analyzed statistically. RESULT: There is overexpression of STAT3, c-myc mRNA and protein in LSCC. The expression of STAT3 and c-myc mRNA in LSCC was associated with clinical stage, differentiation grade and lymph nodal metastases (P < 0.05 or 0.01). The expression of STAT3 and c-myc protein in LSCC was associated with clinical stage and lymph nodal metastases (P < 0.05 or 0.01). There was a positive correlation between the expression of STAT3 and c-myc genes. mRNA and protein, The correlation coefficient (r) was 0.6224 (P < 0.01) for the mRNA expression and 0.7012 (P < 0.01 )for the protein expression. CONCLUSION: The expression of STAT3 and c-myc may play an important role in the tumorigenesis, metastases and poor prognosis of LSCC. There was a positive correlation between the overexpression of STAT3 and c-myc genes in LSCC.

Cucurbitacin B, a small molecule inhibitor of the Stat3 signaling pathway, enhances the chemosensitivity of laryngeal squamous cell carcinoma cells to cisplatin.

We have previously shown that the simultaneous exposure of Hep-2 cells to cucurbitacin B and docetaxel significantly enhances anticancer activity of these cells by suppressing Stat3 activation and down-regulating the expression levels of key cell cycle and anti-apoptosis regulators. In order to determine whether cucurbitacin B can also enhance the sensitivity of Hep-2 laryngeal cells to cisplatin, we treated Hep-2 cells with either cucurbitacin B, cisplatin, or the combination and evaluated these cells for proliferation, cell cycle distribution, and apoptosis. Our results demonstrate that, in comparison to single agent cucurbitacin B or cisplatin treated cells, Hep-2 cells treated with a cucurbitacin B/cisplatin combination display synergistic effects on growth inhibition, cell cycle arrest, and apoptosis induction. Western blot analysis using protein extracts from Hep-2 cells treated with cucurbitacin B, cisplatin, or the combination largely recapitulated the observations made when treated with the cucurbitacin B/docetaxel combination. More specifically, Hep-2 cell lines treated with the cucurbitacin B/cisplatin combination demonstrated a significantly reduced level of p-Stat3 in comparison with single agent treated cells. In addition, cucurbitacin B/cisplatin treated Hep-2 cells also demonstrated a significant reduction in Bcl-2 and Cyclin B1 protein levels compared to single agent cucurbitacin B or cisplatin treated cells. Xenograft models containing Hep-2 cells in mice also demonstrated that this cucurbitacin B/cisplatin combination led to the synergistic inhibition of tumor growth. Taken together, these results suggest that the cucurbitacin B/cisplatin combination treatment may be a potentially useful therapeutic option for individuals diagnosed with laryngeal cancer.