Lipophilic but not hydrophilic statin functionally inhibit volume-activated chloride channels by inhibiting NADPH oxidase in monocytes.

Volume-activated Cl- channels (VACCs) can be activated by hypotonic solutions and have been identified in many cell types. Here, we investigated the effects of different statins on VACCs in monocytes. Whole-cell patch clamp recordings demonstrated that a hypotonic solution induced 5-nitro-2- (3-phenylpropylamino) benzoic acid (NPPB)- and 4,4'-diisothiocyanatostilbene-2, 2'-disulfonic acid (DIDS)-sensitive VACC currents in human peripheral monocytes and RAW 264.7 cells. The VACC currents were inhibited by the lipophilic statin (simvastatin) but not by the hydrophilic simvastatin acid and pravastatin. A low-molecular-weight superoxide anion scavenger (tiron, 1 mM) and inhibitor of NADPH oxidase (DPI 10 µM) was able to abolish the VACC currents. A hypotonic solution increased the reactive oxygen species (ROS) detected by the fluorescence of dichlorodihydrofluorescein (DCF), which was abolished by tiron and DPI. NPPB, DIDS, and simvastatin but not pravastatin decreased the fluorescence of DCF. Simvastatin could not further decrease VACC currents when pretreated with tiron or DPI, whereas exogenous H2O2 (100 µM), increased the VACC currents and overcame the blockade of VACC currents by simvastatin. Functionally, hypotonic solution increased the TNF-α mRNA expression, which could be decreased by tiron, DPI, NPPB, DIDS and simvastatin but not pravastatin. However, simvastatin could not decrease the TNF-α expression further when pretreatment with tiron, DPI, NPPB or DIDS. We conclude that lipophilic (simvastatin) rather than hydrophilic statin inhibit VACCs and decrease hyposmolality induced inflammation in monocytes by inhibiting NADPH oxidase.

Glibenclamide decreases ATP-induced intracellular calcium transient elevation via inhibiting reactive oxygen species and mitochondrial activity in macrophages.

Increasing evidence has revealed that glibenclamide has a wide range of anti-inflammatory effects. However, it is unclear whether glibenclamide can affect the resting and adenosine triphosphate (ATP)-induced intracellular calcium ([Ca(2+)]i) handling in Raw 264.7 macrophages. In the present study, [Ca(2+)]i transient, reactive oxygen species (ROS) and mitochondrial activity were measured by the high-speed TILLvisION digital imaging system using the indicators of Fura 2-am, DCFDA and rhodamine-123, respectively. We found that glibenclamide, pinacidil and other unselective K(+) channel blockers had no effect on the resting [Ca(2+)]i of Raw 264.7 cells. Extracellular ATP (100 µM) induced [Ca(2+)]i transient elevation independent of extracellular Ca(2+). The transient elevation was inhibited by an ROS scavenger (tiron) and mitochondria inhibitor (rotenone). Glibenclamide and 5-hydroxydecanoate (5-HD) also decreased ATP-induced [Ca(2+)]i transient elevation, but pinacidil and other unselective K(+) channel blockers had no effect. Glibenclamide also decreased the peak of [Ca(2+)]i transient induced by extracellular thapsigargin (Tg, 1 µM). Furthermore, glibenclamide decreased intracellular ROS and mitochondrial activity. When pretreated with tiron and rotenone, glibenclamide could not decrease ATP, and Tg induced maximal [Ca(2+)]i transient further. We conclude that glibenclamide may inhibit ATP-induced [Ca(2+)]i transient elevation by blocking mitochondria KATP channels, resulting in decreased ROS generation and mitochondrial activity in Raw 264.7 macrophages.

Extracellular acidic pH-activated, outward rectifying chloride currents can be regulated by reactive oxygen species in human THP-1 monocytes.

Extracellular acidic pH-activated chloride channels (ICl,acid) have been found in a variety of mammalian cells. In the present study, the expression and regulation of ICl,acid were investigated in THP-1 cells. Patch clamp recordings demonstrated that an extracellular acidic solution induced an outward rectified current, which could be blocked by the Cl(-) channel blocker. The currents exhibited time-dependent facilitation and inactivation. The relative anion permeability of this current followed the sequence Cl(-)>Br(-)>I(-)>gluconate. NADPH oxidase inhibitors did not decrease pH 4.4-induced currents. However, reactive oxygen species (ROS) scavengers and mitochondrial inhibitors inhibited pH 4.4-induced currents. Fluorescence imaging of intracellular ROS and mitochondrial activity confirmed these findings. We conclude that ICl,acid occurs in human THP-1 cells and that ICl,acid may be regulated by intracellular ROS mainly originating from mitochondria.

Overexpression of CyclinD1 and underexpression of p16 correlate with lymph node metastases in laryngeal squamous cell carcinoma in Chinese patients.

BACKGROUND: CyclinD1 and p16 are involved in the regulation of G1 checkpoint and may play an important role in the tumorgenesis of laryngeal squamous cell carcinoma (LSCC). Previous studies have examined the level of expression of cyclinD1 or p16 in LSCC but no such information is available for their relation and their correlation with lymph node metastasis in Chinese patients. PATIENTS AND METHODS: A total of 58 patients underwent surgical resection of laryngeal tumours in the Department of Otolaryngology, Qilu Hospital Shandong University between January 2001 and December 2002. All pathologic specimens were available for immunohistochemical study using antibodies against cyclinD1 and p16. RESULTS: Compared with normal epithelium, expression of CyclinD1 in the LSCC was significantly higher (62.1% vs. 10.0%, P < 0.05), expression of p16 was significantly lower (48.3% vs. 90.0%, P < 0.05); CyclinD1 expression in LSCC was up-regulated in TNM classification (r (s) = 0.409, P < 0.05) as well as with cervical lymph node metastases (r (s) = 0.294, P < 0.05); p16 expression in LSCC was down-regulated with cervical lymph node metastases (r (s) = -0.275, P < 0.05); negative significant correlation between p16 immunostaining and CyclinD1 was observed in LSCC (r (s) = -0.331, P < 0.05). CONCLUSION: There was a negative correlation between CyclinD1 expression and p16 expression in LSCC. The over-expression of CyclinD1 and the under-expression of p16 may play a significant role in the incidence and development of LSCC and may be important indicators for cervical lymph node metastases in Chinese patients of LSCC.

[Anti-tumor effect of chemotherapeutic drugs on human gastric cancer cells in vitro and the relationship with Bcl-2 expression].

OBJECTIVE: To evaluate in vitro anti-tumor effect of chemotherapeutic drugs on human gastric cancer cells, and investigate the relationship with Bcl-2 expression. METHODS: Single cell suspension was prepared from fresh gastric cancer tissue and exposed to taxol (Tax), 5-fluorouracil (5-FU), cisplatin (CDDP), adriamycin (ADM), mitomycin (MMC) respectively for 48 hours. Metabolic activity and inhibitory rate of cells were detected by MTT assay. Expression of Bcl-2 was examined with immunohistochemistry. RESULTS: The inhibitory rates of cancer cells exposed to chemotherapeutic drugs were different and Tax, 5-FU, CDDP had remarkably higher rates than ADM and MMC. The lower differentiated gastric cancer cells were more sensitive than the higher ones. Positive expression rate of Bcl-2 was 80% and the positive cells showed resistance to 5-FU, ADM and MMC. CONCLUSIONS: Chemosensitive testing by MTT assay can constitute the prediction for the application of chemotherapeutic drugs individually. Overexpression of Bcl-2 may contribute to multiple drug-resistance of tumors.

[Anti-tumor effects of chemotherapeutic drugs on human gastric cancer cells in vitro and the relationship with expression of hTERT mRNA].

OBJECTIVE: To evaluate in vitro antitumor effects of chemotherapeutic drugs, and investgate the relationship with expression of hTERT mRNA in human gastric cancer tissues. METHODS: Fresh samples of gastric cancer obtained from operation room were prepared to single-cell suspension (3 x 10(5) to 5 x 10(5) cells ml(-1)) and were separately exposed to taxol (TAX), cisplatin (CDDP), 5-fluorouracil (5-Fu), adriamycin (ADM), mitomycin (MMC) for 48 hours. Metabolic activity and inhibitory rate of the cells were determined by trypan blue exclusion and MTT assay. Expression of hTERT mRNA was detected by in situ hybridization (ISH). RESULTS: The inhibition rate of cancer cells exposed to chemotherapeutic drugs was different, and that of TAX, CDDP, 5-Fu was significantly higher than that of ADM and MMC. The positive rate of hTERT mRNA expression was 90.0% (54/60) and positive cells showed resistance to 5-Fu and ADM. CONCLUSION: Overexpression of hTERT mRNA may contribute to primary drug-resistance of tumors. Chemosensitivity tests by MTT assay may contribute to prediction of effectness in applying chemotherapeutic drugs and identify drug-resistant cases.