Anti-cancer effect of metformin on the metastasis and invasion of primary breast cancer cells through mediating NF-kB activity

Current evidence strongly suggests that aberrant activation of the nuclear factor kappa B (NF-kB) signaling cascade is connected to carcinogenesis. The matrix metalloproteinases (MMP) which are also the key agents for tumor metastasis may be potent candidates for tumor diagnosis in clinics. In this in vitro study, we hypothesized that metformin with an effective dose can inhibit tumor cell proliferation and metastasis by modulating the expressions of MMP-2 and -9 and interfering with NF-kB signaling in primary breast cancer cells (PBCCs). 300 000 cells per ml were obtained from biopsies of breast tumors from five human donors. The cell viability and proliferation were tested. Immunocytochemistry was performed for MMP-2, MMP-9, and NF-kB, and enzyme-linked immunosorbent assay for NF-kB activity, quantitative real-time PCR for RELA/p65, IkBα, MMP-2, and MMP-9. Three different doses of metformin (5, 10, and 25 mM) (Met) reduced the viability and proliferation of PBCCs in a dose-dependent manner, maximum inhibition was observed at 25 mM Met. The expression of RELA/p65 was not affected by 25 mM Met. Nuclear immunoreactivity and activity of NF-kB reduced while cytoplasmic NF-kB (p65) elevated by 25 mM Met compared to non-treatment (P < 0.05). The expression and immunoreactivity of MMP-9 but not MMP-2 were decreased by 25 mM Met treatment, compared with the non-treatment (P < 0.05). Metformin may have an essential antitumor role in the invasion and metastasis pathways of PBCCs by downregulating the MMP-9 expression blocking both the activity and nuclear translocation of NF-kB.     

Effects of different surface treatments on shear bond strength in two different ceramic systems

The purpose of this study was to evaluate the influence of different surface treatments (sandblasting, acid etching, and laser irradiation) on the shear bond strength of lithium disilicate-based core (IPS Empress 2) and feldspathic ceramics (VITA VM 9). One hundred ceramic discs were divided into two groups of 50 discs each for two ceramic systems: IPS Empress 2 (group I) and VITA VM 9 (group II). Each of the two groups was further divided into five surface treatment groups (ten each) as follows: group SB, sandblasting with alumina particles (50 μm); group HF, 5 % hydrofluoric acid etching; group L, Er:YAG laser irradiation (distance, 1 mm; 500 mJ; 20 Hz; 10 W; manually, noncontact R14 handpiece); group SB–L, sandblasting + Er:YAG laser; and group HF–L, 5 % hydrofluoric acid + Er:YAG laser. Luting cement (Panavia 2.0) was bonded to the ceramic specimens using Teflon tubes. After 24 h of water storage, a shear bond strength test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed with a two-way analysis of variance (ANOVA) and Tukey's honestly significant difference tests (α?=?0.05). The two-way ANOVA indicated that the shear bond strength was significantly affected by the surface treatment methods (p?<?0.05), but there was no significant interaction between the ceramic systems. Group SB–L had the highest mean values for each ceramic system. Sandblasting, followed by Er:YAG laser irradiation, enhanced the bond strength, indicating its potential use as an alternative method. The atomic force microscopic evaluation revealed that group SB had the most distinct sharp peaks among the groups.     

Fast Transient Fluorescence Technique for Studying Homopolymer Mobility in a Swelling Gel

Summary: The mobility of pyrene end‐capped polystyrene (Py‐PSt) trapped in swollen polystyrene gels (PSt) was investigated. PSt gels were prepared by free radical crosslinking copolymerization (FCC) of styrene (St) and ethylene glycol dimethacrylate (EGDM). The pyrene end‐capped polystyrene was produced by atom transfer radical polymerization (ATRP). After drying, these disc‐shaped PSt gels were left in a toluene solution of Py‐PSt of various molecular weights. During this process, Py‐PSt chains were trapped in the gel. These swollen gels were re‐dried in air and then immersed in pure toluene solution for monitoring the mobility of Py‐PSt chains in and out of the gel. These reswelling experiments were performed at room temperature in real time by monitoring pyrene lifetimes outside (τ₁) and inside (τ₂) of the PSt gel by using in‐situ fast transient fluorescence (FTRF) measurements. It was observed that τ₂ values decrease as swelling proceeds; however, τ₁ values stay constant during swelling. The Li‐Tanaka equation was employed to produce the swelling parameters. The swelling time constant, τ_c was found to increase as the crosslinker density of the gels and the molecular weight, of Py‐PSt chains were increased. It was observed that the collective diffusion coefficient, D_c decreased by increasing the molecular weight by obeying D_c ≈ M^?1 law.

Position of the PSt gel in the fluorescence quartz cell before (a) and after (b) swelling. I₀ and I_p are the excitation and the emission intensities.     

Effect of 5-aminoimidazole-4-carboxamide riboside (AICA-r) on isolated thoracic aorta responses in streptozotocin-diabetic rats.

Diabetes mellitus alters the vascular responsiveness to several vasoconstrictors and vasodilators. 5-amino-4-imidazole-carboxamide riboside (AICA-r), a nucleoside corresponding to AICA-ribotide and an intermediate of the de novo pathway of purine biosynthesis, was recently proposed as a new insulinotropic tool in non-insulin-dependent diabetes mellitus. The aim of the present study was to define whether AICA-r affects altered vascular responsiveness to vasoconstrictors and vasodilators in the thoracic aorta of neonatal streptozotocin (STZ)-diabetic rats. The results of this study indicate that a 1-month treatment with AICA-r significantly increases the body weight in diabetic rats; significantly decreases the blood glucose level of diabetic rats (from 302+/-47 to 135+/-11 mg/dL, p<0.001); does not significantly affect the fast, slow, and total components of responses to noradrenaline in all the experimental groups; reverses the increased Emax values of noradrenaline in diabetic rats to near-control values; reverses the completely abolished responses of acetylcholine (pD2 and percent relaxation) in diabetic rats to control values; and reverses the decreased pD2 values of sodium nitroprussiate in diabetic rats to control values. In conclusion, AICA-r treatment in neonatal STZ-diabetic rats improved increased blood glucose levels, accelerated weight gain, reversed endothelial dysfunction, and normalized vascular responses.     

The effect of a diode laser and traditional irrigants on the bond strength of self-adhesive cement

PURPOSE

The purpose of this study was to compare the effect of a diode laser and traditional irrigants on the bond strength of self-adhesive cement.

MATERIALS AND METHODS

Fifty-five incisors extracted due to periodontal problems were used. All teeth were instrumented using a set of rotary root canal instruments. The post spaces were enlarged for a No.14 (diameter, 1.4 mm) Snowlight (Abrasive technology, OH, USA) glass fiber reinforced composite post with matching drill. The teeth were randomly divided into 5 experimental groups of 11 teeth each. The post spaces were treated with the followings: Group 1: 5 mL 0.9% physiological saline; Group 2: 5 mL 5.25% sodium hypochlorite; Group 3: 5 mL 17% ethylene diamine tetra acetic acid (EDTA), Group 4: 37% orthophosphoric acid and Group 5: Photodynamic diode laser irradiation for 1 minute after application of light-active dye solution. Snowlight posts were luted with self-adhesive resin cement. Each root was sectioned perpendicular to its long axis to create 1 mm thick specimens. The push-out bond strength test method was used to measure bond strength. One tooth from each group was processed for scanning electron microscopic analysis.

RESULTS

Bond strength values were as follow: Group 1 = 4.15 MPa; Group 2 = 3.00 MPa; Group 3 = 4.45 MPa; Group 4 = 6.96 MPa; and Group 5 = 8.93 MPa. These values were analysed using one-way ANOVA and Tukey honestly significant difference test (P<.05). Significantly higher bond strength values were obtained with the diode laser and orthophosphoric acid (P<.05). There were no differences found between the other groups (P>.05).

CONCLUSION

Orthophosphoric acid and EDTA were more effective methods for removing the smear layer than the diode laser. However, the diode laser and orthophosphoric acid were more effective at the cement dentin interface than the EDTA, Therefore, modifying the smear layer may be more effective when a self-adhesive system is used.     

Antiapoptotic effect of angiotensin-II type-1 receptor blockade in renal tubular cells of hyperoxaluric rats

In this study, we investigated the protective effect of losartan as an AT1 receptor antagonist by evaluating the expression of apoptosis-regulatory genes that contribute to the progressive damage in the renal tubules of hyperoxaluric rats. Rats were divided into 4 groups of 10 each; control (C), ethylene glycol (EG), ethylene glycol + losartan (EG + L) and Losartan (L). For 4 weeks 0.8% EG, as a precursor for oxalate, was administered to EG and EG + L and losartan (300 mg/l) was administered to groups EG + L and L. Urine and blood samples were collected for biochemical determination. Bcl-2, bax, caspase-3 and TGF-beta 1 antibodies were used for immunohistochemistry. Apoptosis was determined by TUNEL method. A marked increase in urinary oxalate levels of the rats in EG and EG + L groups was found. In the EG group a diffuse amount of oxalate crystals into the tubular lumina and interstitium in the cortex was observed. In the EG group GBM thickening, interstitial fibrosis and tubular atrophy with infiltration of mononuclear cell findings reduced in the EG + L group were presented as well. In the EG group, immunoreactivity of TGF-beta 1 was increased in glomeruli and tubuli. In the EG + L group, immunoreactivity of TGF-beta 1 was decreased compared to the EG group. Bax expression increased in the renal tubules of EG group and reduced in the EG + L group comparing to the control. In the EG + L group, the immunoreactivity of bcl-2 was increased in glomeruli. In EG + L treated group, number of caspase-3 immunopositive cells were decreased compared to all groups (P < 0.01). Apoptotic cells were increased in the EG-treated group compared to the other groups. Decreased apoptotic cell number was observed in the EG + L compared to the EG group (P < 0.01). Our findings suggest that losartan may provide a beneficial effect against tubulointerstitial damage and decrease renal tubular apoptosis caused by hyperoxaluria.