Arsenic trioxide inhibits invasion/migration in SGC-7901 cells by activating the reactive oxygen species-dependent cyclooxygenase-2/matrix metalloproteinase-2 pathway

Arsenic and Diabetes Mellitus: A Putative Role for the Immune System

Diabetes mellitus (DM) is an enormous public health issue worldwide. Recent data suggest that chronic arsenic exposure is linked to the risk of developing type 1 and type 2 DM, albeit the underlying mechanisms are unclear. This review discusses the role of the immune system as a link to possibly explain some of the mechanisms of developing T1DM or T2DM associated with arsenic exposure in humans, animal models, and in vitro studies. The rationale for the hypothesis includes: (1) Arsenic is a well-recognized modulator of the immune system; (2) arsenic exposures are associated with increased risk of DM; and (3) dysregulation of the immune system is one of the hallmarks in the pathogenesis of both T1DM and T2DM. A better understanding of DM in association with immune dysregulation and arsenic exposures may help to understand how environmental exposures modulate the immune system and how these effects may impact the manifestation of disease.

Maternal Exposure to Di-n-butyl Phthalate Promotes the Formation of Testicular Tight Junctions through Downregulation of NF-κB/COX-2/PGE2/MMP-2 in Mouse Offspring

Previous studies demonstrated that maternal exposure to di-n-butyl phthalate (DBP) resulted in developmental disorder of the male reproductive organ; however, the underlying mechanism has not been thoroughly elucidated to date. The present study was aimed to investigate the effects of maternal exposure to DBP on the formation of the Sertoli cell (SC)-based tight junctions (TJs) in the testes of male offspring mice and the underlying molecular mechanism. By observing the pathological structure and ultrastructure, permeability analysis of the testis of 22 day male offspring in vivo, and transepithelial electrical resistance measurement of inter-SCs in vitro, we found that the formation of TJs between SCs in offspring mice was accelerated, which was paralleled by the accumulation of TJ protein occludin at 50 mg/kg/day DBP exposure in utero and 0.1 mM monobutyl phthalate (MBP, the active metabolite of DBP) in vitro. Our in vitro results demonstrated that 0.1 mM MBP downregulated the expression of matrix metalloproteinase-2 (MMP-2) by inhibiting the activation of nuclear factor-κB (NF-κB)/cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE₂) cascades via attenuated binding of NF-κB to both the MMP-2 promoter and COX-2 promoter. Taken together, the data confirmed that maternal exposure to a relatively low dose of DBP promoted the formation of testicular TJs through downregulation of NF-κB/COX-2/PGE₂/MMP-2, which might promote the development of the testis during puberty. Our findings may provide new perspectives for prenatal DBP exposure, which is a potential environmental contributor, leading to earlier puberty in male offspring mice.

Arsenic Trioxide Suppressed Migration and Angiogenesis by Targeting FOXO3a in Gastric Cancer Cells

Arsenic trioxide (As₂O₃), a traditional remedy in Chinese medicine, has been used in acute promyelocytic leukemia (APL) research and clinical treatment. Previous studies have shown that As₂O₃ exerts its potent antitumor effects in solid tumors by regulating cell proliferation and survival. The aim of this study was to investigate whether As₂O₃ inhibited gastric cancer cell migration and angiogenesis by regulating FOXO3a expression. We found that As₂O₃ reduced gastric cancer cell viability in a dose-dependent manner and also inhibited cell migration and angiogenesis in vitro. Western blotting and immunofluorescence showed that As₂O₃ downregulated the levels of p-AKT, upregulated FOXO3a expression in the nucleus, and attenuated downstream Vascular endothelial growth factor (VEGF) and Matrix metallopeptidase 9 (MMP9) expression. Moreover, we demonstrated that knockdown of FOXO3a significantly reversed the inhibition of As₂O₃ and promoted cell migration and angiogenesis in vitro. Further, As₂O₃ significantly inhibited xenograft tumor growth and angiogenesis by upregulating FOXO3a expression in vivo. However, knockdown of FOXO3a attenuated the inhibitory effect of As₂O₃ in xenograft tumors, and increased microvessel density (MVD) and VEGF expression. Our results demonstrated that As₂O₃ inhibited migration and angiogenesis of gastric cancer cells by enhancing FOXO3a expression.

Downregulation of P-gp, Ras and p-ERK1/2 contributes to the arsenic trioxide-induced reduction in drug resistance towards doxorubicin in gastric cancer cell lines

Multidrug resistance (MDR) to doxorubicin (DOX) limits its effectiveness against tumor cells. Arsenic trioxide (As₂O₃) has been reported to reduce MDR in various types of cancer, but the mechanisms involving Ras and p-glycoprotein (P-gp) remain to be fully elucidated. The objectives of the present study were to evaluate As₂O₃ in reversing MDR to DOX, and to identify the association in antitumor activities between the effectiveness of DOX and Ras/phosphorylated (p-) extracellular signal-regulated kinase (ERK)1/2 signaling in SGC7901/ADM and SGC7901/S human gastric cancer cell lines. Cytotoxicity and sensitivity towards As₂O₃ were assessed using non-toxic and mildly-toxic concentrations (0.1 and 0.5 µM, respectively). The reversing effect of As₂O₃ on MDR was investigated prior to and following treatment with a cytokine activation of the recombinant human granulocyte colony stimulating factor ERK pathway. The SGC7901/ADM and SGC7901/S cells had the same sensitivity to As₂O₃. The SGC7901/ADM cells were resistant to DOX and As₂O₃ treatment reduced the level of resistance to DOX (P<0.01). The expression of P-glycoprotein (P-gp) in the SGC7901/ADM cells was higher than in the SGC7901/S cells (P<0.001). As₂O₃ treatment decreased the levels of P-gp in a time- and dose-dependent manner (P<0.01). The expression of Ras was higher in the SGC7901/ADM cells than in the SGC7901/S cells, while the expression of p-ERK1/2 remained the same. As₂O₃ decreased the levels of Ras and p-ERK1/2 (P<0.01). Following pretreatment with rhG-CSF, the levels of Ras and p-ERK1/2 were further decreased (P<0.01). Drug-resistant gastric cancer cells had higher expression levels of P-gp and Ras, but not of p-ERK1/2. Non- and mildly-toxic doses of As₂O₃ reduced MDR to DOX through Ras/p-ERK1/2 signaling.

Molecular mechanism of the inhibition effect of Celecoxib on corneal collagen degradation in three dimensions

AIM

To clarify the molecular mechanism of Celecoxib on corneal collagen degradation and corneal ulcer.

METHODS

Rabbit corneal fibroblasts were harvested and suspended in serum-free MEM. Type I collagen, DMEM, collagen reconstitution buffer and corneal fibroblast suspension were mixed on ice. The resultant mixture solidify in an incubator, after which test reagents and plasminogen was overlaid and the cultures were returned to the incubator. The supernatants from collagen gel incubations were collected and the amount of hydroxyproline in the hydrolysate was measured. Immunoblot analysis of MMP1, 3 and TIMP1, 2 was performed. MMP2, 9 was detected by the method of Gelatin zymography. Cytotoxicity Assay was measured.

RESULTS

Celecoxib inhibited corneal collagen degradation in a dose and time manner; Celecoxib inhibited the IL-1ß induced increases in proMMP1, 2, 3, 9 and active MMP1, 2, 3, 9 in a concentration-depended manner. Celecoxib can also inhibit the IL-1ß induced increases in the TIMP1, 2.

CONCLUSION

Celecoxib can inhibit corneal collagen degradation induced by IL-1β, this effect is the consequence of the reduction of MMP1, 2, 3, 9 and TIMP1, 2. The results of the present study provide new insight into Celecoxib in corneal ulcer treatment.

Arsenic trioxide inhibits cell growth and induces apoptosis through inactivation of notch signaling pathway in breast cancer

Arsenic trioxide has been reported to inhibit cell growth and induce apoptotic cell death in many human cancer cells including breast cancer. However, the precise molecular mechanisms underlying the anti-tumor activity of arsenic trioxide are still largely unknown. In the present study, we assessed the effects of arsenic trioxide on cell viability and apoptosis in breast cancer cells. For mechanistic studies, we used multiple cellular and molecular approaches such as MTT assay, apoptosis ELISA assay, gene transfection, RT-PCR, Western blotting, and invasion assays. For the first time, we found a significant reduction in cell viability in arsenic trioxide-treated cells in a dose-dependent manner, which was consistent with induction of apoptosis and also associated with down-regulation of Notch-1 and its target genes. Taken together, our findings provide evidence showing that the down-regulation of Notch-1 by arsenic trioxide could be an effective approach, to cause down-regulation of Bcl-2, and NF-κB, resulting in the inhibition of cell growth and invasion as well as induction of apoptosis. These results suggest that the anti-tumor activity of arsenic trioxide is in part mediated through a novel mechanism involving inactivation of Notch-1 and its target genes. We also suggest that arsenic trioxide could be further developed as a potential therapeutic agent for the treatment of breast cancer.

Effect of 5-Aza-2'-deoxycytidine and trichostatin A on expression and methylation of the Runx3 gene in human gastric carcinoma line SGC-7901

AIM: To evaluate the effect of 5-Aza-2'-deoxy-citydine (5-Aza-dC) and trichostatin A (TSA) on the methylation and expression of the Runx3 gene in human gastric cancer cell line SGC-7901.

METHODS: After cultured SGC-7901 cells were treated with 5-Aza-dC and TSA, the methylation levels of the promoter region of the Runx3 gene were detected by quantitative real-time methylation-specific polymerase chain reaction (QMSP), and Runx3 mRNA and protein expression was detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively.

RESULTS: Treatment with 5-Aza-dC or TSA alone reduced the methylation levels of the promoter region of the Runx3 gene (70%, 63% vs 100%) and increased Runx3 mRNA (0.29 ± 0.01, 0.28 ± 0.03 vs 0.14 ± 0.03, both P < 0.05) and protein expression levels (0.35 ± 0.02, 0.37 ± 0.02 vs 0.09 ± 0.01, P < 0.05) compared to control cells. Treatment with 5-Aza-dC in combination with TSA could more significantly reduce Runx3 gene promoter methylation levels (37%) and increase Runx3 mRNA (0.45 ± 0.02) and protein expression levels (0.50 ± 0.01) compared to cells treated with 5-Aza-dC or TSA alone (all P < 0.05).

CONCLUSION: 5-Aza-dC and TSA can synergistically reverse Runx3 gene methylation and recover Runx3 mRNA and protein expression in SGC-7901 cells.