Activation of NLRP3 inflammasome promotes the proliferation and migration of esophageal squamous cell carcinoma

Inflammasomes can identify endogenous danger signals as an inflammatory immune response. As the most common inflammasome, the NLR pyrin family domain containing 3 (NLRP3) inflammasome is associated with the pathogenesis of different tumors. However, the function of the NLRP3 inflammasome in esophageal cancer (EC) has rarely been reported. Herein, the expression levels of the components of NLRP3 inflammasome and Ki-67 were analyzed by immunohistochemistry. Furthermore, correlations between the NLRP3 inflammasome and Ki-67 along with the clinicopathological features of EC patients were evaluated. The components of the NLRP3 inflammasome were also assessed by western blot analysis and quantitative PCR. NLRP3 was silenced or overexpressed in different esophageal squamous cell carcinoma (ESCC) cell lines, and cell viability, migration and invasion were assessed by CCK-8 and Transwell assays. The present results showed that high NLRP3 expression in the tumor specimens was significantly associated with TNM stage and T category. Spearman's correlation analysis revealed a positive correlation between NLRP3 and the Ki-67 proliferation index. The mRNA and protein levels of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), cleaved caspase-1, and interleukin (IL)-1β in tumor tissues were higher than those in non-cancerous tissues. The level of secreted IL-1β in tumor tissues was also increased, as compared to that in normal tissues. Silencing of NLRP3 in KYSE-70 and TE13 cells strongly attenuated cell viability, decreased cell mobility in wound-healing assays and greatly diminished the ability of cell migration and invasion in the Transwell system. Overexpression of NLRP3 in KYSE-510 and EC9706 cells markedly promoted the proliferation, migration and invasion. Collectively, these results revealed that the the NLRP3 inflammasome is upregulated in human ESCC tissues and promotes ESCC progression. Hence, NLRP3 could be a promising new candidate diagnostic and prognostic target.

Blockage of hERG current and the disruption of trafficking as induced by roxithromycin

Roxithromycin is an oral macrolide antibiotic agent that has been repeatedly reported to provoke excessive prolongation of the Q–T interval and torsades de pointes in clinical settings. To investigate the mechanisms underlying the arrhythmogenic side effects of roxithromycin, we studied the molecular mechanisms of roxithromycin on human ether-à-go-go-related gene (hERG) K+ channels expressed in human embryonic kidney (HEK293) cells. Roxithromycin was found to inhibit wild-type (WT) hERG currents in a concentration-dependent manner with a half-maximum block concentration (IC50) of 55.8 ± 9.1 μmol/L. S6 residue hERG mutants (Y652A and F656C) showed reduced levels of hERG current blockage attributable to roxithromycin. Roxithromycin also inhibited the trafficking of hERG protein to the cell membrane, as confirmed by Western blot analysis and confocal microscopy. These findings indicate that roxithromycin may cause acquired long-QT syndrome via direct inhibition of hERG current and by disruption of hERG protein trafficking. Mutations in drug-binding sites (Y652A or F656C) of the hERG channel were found to attenuate hERG current blockage by roxithromycin, but did not significantly alter the disruption of trafficking.

Cancer stem cells niche: a target for novel cancer therapeutics

Nowadays, cancer has been a frequent disease, and the first or second most common cause of death worldwide. Despite a better understanding of the biology of cancer cells, the therapy of most cancers has not significantly changed for the past four decades. It is because conventional chemotherapies and/or radiation therapies are usually designed to eradicate highly proliferative cells. Mounting evidence has implicated that cancer is a disease of stem cells. Cancer stem cells (CSC) are often relatively quiescent, and therefore may not be affected by therapies targeting rapidly dividing cells. Like normal stem cells (NSC) residing in a "stem cell niche" that maintains them in a stem-like state, CSC also require a special microenvironment to control their self-renewal and undifferentiated state. The "CSC niche" is likely to be the most crucial target in the treatment of cancer. In this article, we summarize the current knowledge regarding CSC and their niche microenvironments. Understanding of CSC's origin, molecular profile, and interaction with their microenvironments, this could be a paradigm shift in the treatment of cancer, away from targeting the blast cells and towards the targeting of the CSC, thus improving therapeutic outcome.

Down-regulation of Trop-2 expression inhibits cell proliferation and migration in human esophageal squamous cell carcinoma cell line EC9706

AIM: To investigate the effect of down-regulation of tumor-associated calcium signal transducer-2 (Trop-2) expression on cell proliferation and migration in human esophageal squamous cell carcinoma (ESCC) cell line EC9706 and to explore possible molecular mechanisms involved.

METHODS: Trop-2-specific small interfering RNA (siRNA) and control siRNA were transfected into EC9706 cells, and expression of Trop-2 mRNA and protein was detected by real-time PCR and Western blotting. CCK-8 assay was used to measure cell proliferation, and Boyden chamber assay was utilized to determine cell migration. The expression of cell migration-related MMP-7 protein was detected by Western blotting.

RESULTS: The expression of Trop-2 mRNA and protein in the Trop siRNA group was significantly lower than that in the normal control group or control siRNA group 48 h after transfection. SiRNA-mediated down-regulation of Trop-2 expression obviously inhibited cell proliferation and migration compared to the normal control group and control siRNA group (65.29 ± 4.33 vs 119.27 ± 4.63, 112.81 ± 5.01, both P < 0.05). Transfection of Trop-2-specific siRNA markedly decreased the expression of MMP-7 protein in EC9706 cells.

CONCLUSION: Down-regulation of Trop-2 expression inhibits the proliferation and migration of EC9706 cells possibly by down-regulating MMP-7 expression. Trop-2 might be used as a molecular target for therapy of ESCC.

Effects of subcellular localization pattern of PpIX on photodynamic efficiency in esophageal cancer cells

AIM: To study the effects of subcellular localization pattern of PpIX on photodynamic efficiency in esophageal cancer cell lines.

METHODS: KYSE-450, KYSE-70 and Het-1A cells were treated with ALA, exogenous PpIX and MitoTracker, respectively. The subcellular localization patterns of PpIX were observed using fluorescence microscopy. Mitochondrial transmembrane potential (ΔΨm) after ALA-PDT and PpIX-PDT was measured using JC-1 flow cytometry. The morphological study of mitochondria after ALA-PDT and PpIX-PDT was performed with electron microscopy. MTS was used to examine the cell survival rate.

RESULTS: The granular patterns and distribution of fluorescence in the extranuclear fraction of the cells were similar for both ALA-derived endogenous PpIX and the MitoTracker in all cell lines; however, exogenous PpIX was diffusely distributed in the whole cytoplasm of cells. After 12 h of ALA-based PDT, the percentages were increased to 22%, 52% and 33% in the KYSE-450, KYSE-70 and Het-1A cell lines, respectively; where only 15%, 14% and 18% of the depolarized cell fractions were seen following PDT with exogenous PpIX. As early as 1 h after photodynamic treatment, some of the mitochondria were already damaged by ALA-PDT with unclear cristae, vacuoles and swelling; while the mitochondrial ultrastructure was still well preserved 1 h later following PDT with exogenous PpIX. ALA-mediated PDT was significantly more efficient than PDT with exogenous PpIX in killing cells in all the 3 cell lines.

CONCLUSION: Different subcellular location of photosensitizer may affect the PDT efficacy. Mitochondria are more sensitive and may be important targets for PDT. This finding suggests that new photosensitizers with mitochondrially-localizing property may be designed for improvement of PDT effectiveness in the future.