0165), being significantly (10%) lower during Sedation/Entangled than in the Disentangled phase (Z  =  −2.7230, P = 0.0065; Fig. 8). There was no significant difference between ODBA in dive descents between Disentangled and Recovery phases (Z  =  −1.2603, P = 0.2076). During ascents, ODBA did not differ significantly between phases (χ2 = 2.8613, P = 0.2392; Fig. 8). Mean drag forces (N) of gear removed from Eg 3911 were consistently though not significantly

greater at all speeds with buoys attached (Table 4). Sinkline drag forces were intermediate between gear-only and gear-and-buoy configurations (Table 4). Mean drag forces showed no significant difference between surface and 2 m anchor points for gear-only (P = 0.4595), gear-and-buoys (P = 0.4888) or sinkline (P = 0.4965) configurations (Devore 2008). The mean theoretical drag coefficient of a nonentangled right whale (Cd,n) of Eg 3911′s dimensions, swimming at 0.75–2.9 m/s ranged from selleckchem 3.7 × 10−3 to 2.9 × 10−3, respectively (mean ± SD; Cd,n = 3.2 × 10−3 ± 0.0003; Fig. 9). The

drag coefficient for each entangled gear scenario was calculated by applying Equation (6) (Cd = DT/(1/2)ρU2Awγkg). Though drag coefficients for Eg 3911 entangled in all gear configurations differed based on the value of k (Fig. 10), the most conservative estimates with k = 3 (Cd,e,go = 3.4 × 10−3 ± 0.0003, Cd,e,gb = 3.7 × 10−3 ± 0.0003, Cd,e,sl = 3.8 × 10−3 ± 0.0004) were significantly greater than in the nonentangled case (Wilcoxon signed rank, P = 0.0156, 0.0312, 0.0078, respectively). Having click here made low (Kleiber) and high (3 ×  Kleiber) estimates 上海皓元医药股份有限公司 of BMR, and using two values of k (1 and 3), we present drag and power requirements as the lower (k = 1, BMR = Kleiber) and upper (k = 3, BMR = 3 ×  Kleiber) bounds of the model results. Drag forces on Eg 3911 while not entangled ranged from 37.2 N to 1,263 N at 0.75–2.9 m/s. The associated total power requirements in the nonentangled condition (Eq. 11) ranged from 2,791 W to 16,140 W (Fig 10). Locomotory power requirements ranged from 191 W to 25,021 W. Drag forces on Eg 3911 entangled in various gear configurations are summarized

in Table 5. Across all gear configurations, mean entangled drag values ranged from 62.1 N to 2,421 N. Increases in total power input over the normal (nonentangled) condition ranged from 4.1% to 58.8% for the gear-only configuration, 4.9% to 82.5% for the sinkline configuration, and 4.8% to 120.9% for the gear-and-buoy configuration (Fig. 9). Locomotory power requirements increased on average 70.5% (SD 9.5) for the gear-only configuration, 91.0% (22.5) for the sinkline configuration, and 101.9% (31.9) for the gear-and-buoy configuration (total range 60.0%–164.6%). Alternatively, to maintain the same power output over the range of swimming speeds, an individual entangled in gear-only, sinkline, and gear-and-buoy configurations would need to decrease swimming speed by 16.2% (SD 1.5), 19.2% (3.0), or 20.5% (3.9), respectively (total range 14.5%–27.7%).

3B). UDCA treatment did not affect serum 4β-HC or 24S-HC concentrations but PD-0332991 chemical structure increased the 27-HC concentration significantly. Treatment with bezafibrate clearly increased serum 4β-HC levels, whereas it significantly reduced the 24S-HC and 27-HC levels. Differentiated HepaRG cells exhibit a gene expression pattern similar to primary human hepatocytes and human liver tissues and maintain significant levels of hepatic cell functions, including CYP and transporter activities.26 Rifampicin and carbamazepine are classical inducers of CYP3A4 by way of the activation of PXR,27 whereas GW4064 is one of the most potent agonists of FXR.28 As shown in Fig. 4A, bezafibrate, as well as rifampicin

and carbamazepine, induced both CYP3A4 mRNA expression

and activity in a dose-dependent manner. The DPX2 cell-based luciferase reporter gene assay demonstrated that in comparison with rifampicin, bezafibrate was a weak but significant activator of human PXR as well as carbamazepine (Fig. 4B). It is noteworthy that GW4064 activated human PXR at concentrations higher than 3 μM. Among the nuclear receptors and related coactivators (Fig. 5A), PXR expression was induced by bezafibrate to a greater degree than that by rifampicin, which suggests that PXR is a target gene of PPARs, as reported.29 In contrast, the small heterodimer partner (SHP; NR0B2), a target of FXR, and LXRα were down-regulated by bezafibrate, as well as rifampicin and carbamazepine. FXR and peroxisome proliferator-activated Alisertib research buy receptor-γ coactivator-1α (PGC1α) expressions were significantly down-regulated by rifampicin and carbamazepine but not by bezafibrate. The MDR1 (ABCB1) and MRP2 (ABCC2) transporters (Fig. 5B) were up-regulated

by bezafibrate, similar to rifampicin, whereas MDR3, ABCG5, and ABCG8 were up-regulated by bezafibrate but not by rifampicin. In addition, Na+/taurocholate cotransporting polypeptide (NTCP) was down-regulated by medchemexpress bezafibrate but did not change significantly by rifampicin. It is notable that significant messenger RNA (mRNA) expression of BSEP was observed in HepaRG cells treated with GW4064, whereas only a trace amount of BSEP expression was detected in control cells and those treated with other compounds. Enzymes involved in cholesterol, bile acid, and fatty acid syntheses and LDL receptor expression are summarized in Fig. 5C. CYP7A1, CYP7B1, and CYP27A1 were down-regulated and CYP8B1, fatty acid synthase (FAS), and LDL receptor (LDLR) were up-regulated by bezafibrate, which was the same as the effects of rifampicin. HMG-CoA reductase (HMGCR), the rate-limiting enzyme in the cholesterol biosynthetic pathway, was down-regulated by rifampicin but was slightly up-regulated by bezafibrate. Our results clearly showed that the combination therapy of bezafibrate and UDCA significantly improved cholestasis in early-stage PBC patients who were refractory to UDCA monotherapy.

3B). UDCA treatment did not affect serum 4β-HC or 24S-HC concentrations but CH5424802 supplier increased the 27-HC concentration significantly. Treatment with bezafibrate clearly increased serum 4β-HC levels, whereas it significantly reduced the 24S-HC and 27-HC levels. Differentiated HepaRG cells exhibit a gene expression pattern similar to primary human hepatocytes and human liver tissues and maintain significant levels of hepatic cell functions, including CYP and transporter activities.26 Rifampicin and carbamazepine are classical inducers of CYP3A4 by way of the activation of PXR,27 whereas GW4064 is one of the most potent agonists of FXR.28 As shown in Fig. 4A, bezafibrate, as well as rifampicin

and carbamazepine, induced both CYP3A4 mRNA expression

and activity in a dose-dependent manner. The DPX2 cell-based luciferase reporter gene assay demonstrated that in comparison with rifampicin, bezafibrate was a weak but significant activator of human PXR as well as carbamazepine (Fig. 4B). It is noteworthy that GW4064 activated human PXR at concentrations higher than 3 μM. Among the nuclear receptors and related coactivators (Fig. 5A), PXR expression was induced by bezafibrate to a greater degree than that by rifampicin, which suggests that PXR is a target gene of PPARs, as reported.29 In contrast, the small heterodimer partner (SHP; NR0B2), a target of FXR, and LXRα were down-regulated by bezafibrate, as well as rifampicin and carbamazepine. FXR and peroxisome proliferator-activated selleck screening library receptor-γ coactivator-1α (PGC1α) expressions were significantly down-regulated by rifampicin and carbamazepine but not by bezafibrate. The MDR1 (ABCB1) and MRP2 (ABCC2) transporters (Fig. 5B) were up-regulated

by bezafibrate, similar to rifampicin, whereas MDR3, ABCG5, and ABCG8 were up-regulated by bezafibrate but not by rifampicin. In addition, Na+/taurocholate cotransporting polypeptide (NTCP) was down-regulated by MCE公司 bezafibrate but did not change significantly by rifampicin. It is notable that significant messenger RNA (mRNA) expression of BSEP was observed in HepaRG cells treated with GW4064, whereas only a trace amount of BSEP expression was detected in control cells and those treated with other compounds. Enzymes involved in cholesterol, bile acid, and fatty acid syntheses and LDL receptor expression are summarized in Fig. 5C. CYP7A1, CYP7B1, and CYP27A1 were down-regulated and CYP8B1, fatty acid synthase (FAS), and LDL receptor (LDLR) were up-regulated by bezafibrate, which was the same as the effects of rifampicin. HMG-CoA reductase (HMGCR), the rate-limiting enzyme in the cholesterol biosynthetic pathway, was down-regulated by rifampicin but was slightly up-regulated by bezafibrate. Our results clearly showed that the combination therapy of bezafibrate and UDCA significantly improved cholestasis in early-stage PBC patients who were refractory to UDCA monotherapy.

Infants in the group of treated mothers had a lower HBsAg seropositivity (10/56 vs 23/59 or 18% vs 39%, P = 0.014).34 Unfortunately, selleck kinase inhibitor the high rate of lost to follow up or consent withdrawal weakened the conclusions of this important study. Hence, whether giving antivirals to near-term HBV carrier mothers will decrease the perinatal mother-to-infant HBV infection needs to be addressed further with randomized control trials. In dealing with this issue, the cost and safety in both the mothers

and newborns should also be considered. Pregnancy category of the currently available drugs for the treatment of chronic hepatitis B is shown in Table 2. In most instances, the reservation is because of insufficient data in humans to guarantee absence of embryonal adverse effects including teratogenicity. In this regard, the experience in HIV infection is extremely helpful.35 Because humans are the only reservoir of HBV, if HBV can be eradicated, or strongly and

effectively suppressed in the human HBsAg carriers, it will prevent spreading HBV to others, and thus will be an important step toward the elimination and eradication of hepatitis B. The transmission routes of HBV can be classified into horizontal and perinatal (“vertical”) modes (Fig. 2). HBV is highly infectious, because a very tiny amount of body fluids from an HBV carrier can contain a large number of viruses, and infect a susceptible person through mucocutaneous disruptions. Intimate contacts with a virus carrier PLX-4720 in vivo such as household activities and sharing toys among children can cause the infection. Sexual transmissions are also well-documented. Use of condoms may help to prevent such transmissions. Ear or other body piercings, acupuncture, tattoo or any procedures that disrupt mucocutaneous barriers are

all potentially dangerous. All the instruments that are used in these procedures should be adequately sterilized. Unsafe injections by using unsterilized or inadequately sterilized needles and syringes also result in the spread of HBV.36 This is most serious in illicit injection drug users. MCE Whether a needle/syringe exchange program will reduce the risk of HBV infection among the injection drug users remains to be seen.37,38 Insect bites have also been suspected to spread HBV, but the evidence does not seem strong. On the other hand, transfusion of blood or blood products is also an important route of transmission. Despite screening by sensitive serological assays, HBV transmission still occurs in a substantial proportion of susceptible recipients.39 Based on the results of a prospective study in Taiwan from 1987–1994, it was projected that approximately 200 cases of post-transfusion HBV infection could occur for every 1 million units of transfused blood in Taiwan where HBV infection is hyperendemic.

These insulin-sensitizing actions were consistent with the presence of lower serum glucose concentrations, the normalization of hepatic glycogen content, and the improvement of insulin tolerance tests in ApoE−/−/5-LO−/− mice. A salient aspect of PI3K inhibitor our study was that hepatocytes isolated from ApoE−/− mice lacking 5-LO were more resistant to apoptosis, an effect that was consistent with our in vivo findings demonstrating protection against inflammatory liver injury. The role of 5-LO in hepatocyte apoptosis was

addressed using two different strategies that allowed a similar conclusion to be reached. On one hand, we observed higher apoptosis in hepatocytes isolated from ApoE−/− mice compared with WT, whereas hepatocytes isolated from ApoE−/−/5-LO−/−

were more resistant to apoptosis, even following treatment with actinomycin D, which is a potent RNA inhibitor that sensitizes hepatocytes to TNF-α–induced apoptosis by blocking see more the expression of NF-κB–dependent survival genes.24 On the other hand, we observed that 5-LO products (LTB4, LTD4, and 5-HETE) by themselves sensitized hepatocytes to TNF-α–induced apoptosis and potentiated the apoptotic effects of actinomycin D. Although the mechanisms underlying the proapoptotic effects of 5-LO products in hepatocytes are not completely delineated, we obtained convincing data indicating that this effect could be related to NF-κB inhibition. Indeed, in the presence of TNF-α and actinomycin D, an apoptotic condition in which NF-κB is critical for hepatocyte survival, 5-LO products exerted

a significant inhibition of this transcription factor, whereas they induced NF-κB activity when survival was not compromised by actinomycin D. Similar findings demonstrating NF-κB activation by 5-LO products under inflammatory conditions have been reported in monocytes and smooth muscle vascular cells.26, 27 These findings are also consistent with our in vivo data showing that NF-κB activity is significantly decreased in ApoE−/− mice lacking Alox5. One of the novel aspects provided by this study is that it demonstrates that absence of 5-LO alters the transition from steatosis to steatohepatitis in a hyperlipidemic model of nonalcoholic steatohepatitis. This study is also novel because it uses a genetic approach to demonstrate that 5-LO is involved in liver disease. It also adds new data to our previous studies demonstrating the up-regulation medchemexpress of 5-LO in different models of liver injury, including ob/ob mice with NAFLD and rats with CCl4-induced hepatic inflammation and fibrosis.10, 14 In the CCl4 model, 5-LO products appear to be specific mediators of inflammation and cell damage, because inhibition of their formation with either a direct 5-LO inhibitor or a potent FLAP inhibitor exerted protective actions against necroinflammatory liver damage and fibrosis.11–13 Similar findings have been reported using thioacetamide, D-galactosamine, and bile duct ligation models of liver injury.

In 2010, 30.6% of respondents reported that they treated patients fewer than 30 hours per week compared to 30% in 2007. The percent of respondents who treated patients for 30 to 39 hours per week declined from 54.9% in 2007 to 45.8% in 2010. Respondents reported an average of 34.6 hours in the practice and 30.0 hours in the practice treating patients. On average, prosthodontists spent (in 2010) about 4.6 hours in the office per week conducting activities other than treatment of patients, including administration, supervision, lab work, meetings, research, and other office activities. The survey was also used to determine how prosthodontists spend their treatment time. Prosthodontists were asked

to report the percent of their treatment time spent in providing various dental procedures and the percent selleck screening library of billings received by type of procedure rendered (Fig 5). The data shown in Figure 5 are the average

percent of time spent by prosthodontists in the procedure categories shown and the average percent of billings associated Buparlisib purchase with each procedure. The percent of time rendering a procedure and the percent of billings are closely related (Fig 5). Prosthodontist respondents reported that they spend about 21% of their time rendering fixed prosthodontics services, which were about 23% of their billings. About 80% of a prosthodontist’s time and billings is for six services including fixed prosthodontics, implant restoration, complete dentures, operative care, diagnostic care, and removable dentures. Figure 6 上海皓元 contains results comparing the percent of time rendering selected prosthodontic

services in 2007 and 2010. The average percent of time rendering fixed prosthodontics (excluding implants) has declined over the 3-year period, from 24.1% of the time in 2007 to 21.2% in 2010. Percent of time in implant restoration increased slightly, and implant placement declined over the 3-year period from 2007 to 2010. Percent of time in complete dentures declined from 12.5% in 2007 to 11.7% in 2010. Expenses of the practice were another economic activity reviewed by the survey. The nominal mean total practice expense per prosthodontist was $538,230 in 2010 compared to $518,255 in 2007. Expenses per prosthodontist are calculated by dividing the expenses reported for the practice by the total number of prosthodontists treating patients in the practice (full-time [FT] or part-time [PT], owners or nonowners). While mean overall expenses per prosthodontist increased, not all expense categories increased (Fig 7). Relative increases occurred in practice supply expense and employee taxes. Decreases in expenses per prosthodontist occurred for staff salaries, commercial lab charges, in-house lab charges, and officer salaries. The nominal mean salaries of officers declined by 34% over the period 2007 to 2010. Average nominal expenses per prosthodontist declined 86% for in-house lab, declined 29% for commercial lab, and declined 11% for staff salaries (Fig 7).

In 2010, 30.6% of respondents reported that they treated patients fewer than 30 hours per week compared to 30% in 2007. The percent of respondents who treated patients for 30 to 39 hours per week declined from 54.9% in 2007 to 45.8% in 2010. Respondents reported an average of 34.6 hours in the practice and 30.0 hours in the practice treating patients. On average, prosthodontists spent (in 2010) about 4.6 hours in the office per week conducting activities other than treatment of patients, including administration, supervision, lab work, meetings, research, and other office activities. The survey was also used to determine how prosthodontists spend their treatment time. Prosthodontists were asked

to report the percent of their treatment time spent in providing various dental procedures and the percent AZD6244 in vitro of billings received by type of procedure rendered (Fig 5). The data shown in Figure 5 are the average

percent of time spent by prosthodontists in the procedure categories shown and the average percent of billings associated selleckchem with each procedure. The percent of time rendering a procedure and the percent of billings are closely related (Fig 5). Prosthodontist respondents reported that they spend about 21% of their time rendering fixed prosthodontics services, which were about 23% of their billings. About 80% of a prosthodontist’s time and billings is for six services including fixed prosthodontics, implant restoration, complete dentures, operative care, diagnostic care, and removable dentures. Figure 6 medchemexpress contains results comparing the percent of time rendering selected prosthodontic

services in 2007 and 2010. The average percent of time rendering fixed prosthodontics (excluding implants) has declined over the 3-year period, from 24.1% of the time in 2007 to 21.2% in 2010. Percent of time in implant restoration increased slightly, and implant placement declined over the 3-year period from 2007 to 2010. Percent of time in complete dentures declined from 12.5% in 2007 to 11.7% in 2010. Expenses of the practice were another economic activity reviewed by the survey. The nominal mean total practice expense per prosthodontist was $538,230 in 2010 compared to $518,255 in 2007. Expenses per prosthodontist are calculated by dividing the expenses reported for the practice by the total number of prosthodontists treating patients in the practice (full-time [FT] or part-time [PT], owners or nonowners). While mean overall expenses per prosthodontist increased, not all expense categories increased (Fig 7). Relative increases occurred in practice supply expense and employee taxes. Decreases in expenses per prosthodontist occurred for staff salaries, commercial lab charges, in-house lab charges, and officer salaries. The nominal mean salaries of officers declined by 34% over the period 2007 to 2010. Average nominal expenses per prosthodontist declined 86% for in-house lab, declined 29% for commercial lab, and declined 11% for staff salaries (Fig 7).

5 cells in poly-D-lysine-coated 96-well plates. The AR4A batch had previously been tested,[9]

whereas a new HC84.26 batch was used. After washing and 48-hour incubation, NS5A antigen staining was performed with 9E10 Ab, and ffu counts were determined as indicated above. The mean background level of six negative wells was below 15 in all experiments; the negative mean was subtracted from ffu counts in experimental wells. As controls, previously tested HCV-negative sera were tested against the J6/JFH1ΔHVR1 and J8/JFH1ΔHVR1 viruses,[21] and HCV-positive, IgG-depleted serum was tested against J6/JFH1 and J6/JFH1ΔHVR1. Everolimus price Unmodified viruses were tested against b6, an AR4A control, and against R04, an HC84.26 control.[9, 10] Percent Selleck INCB018424 neutralization was calculated by relating the mean ffu of the experimental wells in three replicates for serum and four replicates for HMAb samples

to the mean of six replicate cultures inoculated with virus only.[16] The serum dilution and IgG concentration against HVR1-deleted culture viruses and the HMAb-concentration against unmodified culture viruses causing 50% reductions in ffu (half-maximal inhibitory concentration; IC50) were determined by best-fit sigmoidal dose-response curves with variable slope and bottom constraint of 0 (Y = Bottom + (Top − Bottom)/(1 + 10(log10IC50-X)*Hillslope); GraphPad Prism; GraphPad Software Inc., La Jolla, CA). Because of limited neutralization of the unmodified recombinant viruses by patient serum and IgG, IC50 values were instead

reported as the highest serum dilution or the lowest concentration of IgG where neutralization ≥50% was observed. For development of JFH1-based recombinants, we determined the Core-NS2 consensus sequence deduced from five to seven molecular clones from each patient’s viral population (Supporting Table 2). The variation between the T9 Core-NS2 consensus and the five clonal sequences was <0.6% at the nucleotide (nt) and amino acid (aa) level. For DH8 and S83, six of seven clones analyzed diverged <1% from MCE the respective consensus sequences; for each isolate, there was a single clone deviating by 2.0%-3.5%. The DH10 quasispecies consisted of two subpopulations separated in five and two clones, respectively. The DH10 consensus was developed from the most prevalent subpopulation, deviating from the consensus by <0.2%. As for prototype strains J6(2a) and J8(2b), the Core-NS2 of T9(2a), DH8(2b), DH10(2b), and S83(2c) consisted of 3,090 nts encoding 1,030 aa. At the aa level, the Core-NS2 of T9(2a) differed from J6(2a) by 9.5%, whereas DH8(2b) and DH10(2b) differed from J8(2b) by 8.2% and 8.7%, respectively. S83(2c) differed from J6(2a) and J8(2b) by 18.5% and 20.5%, respectively. Thus, Core-NS2 sequences of the novel genotype 2 isolates deviated significantly from those of the previously developed genotype 2 recombinants (Fig. 1).

Mutations, APC; 2. Beta Catenin; 3. Colorectal Cancer; 4. q-RTPCR, IHC; Presenting Author: LIN XIA Additional Authors: RUI DU, DEXIN ZHANG, XINMIN ZHOU, DAMING Tamoxifen nmr FAN Corresponding Author: LIN XIA Affiliations: Xijing Hospital of Digestive Diseases & State Key Laboratory of Cancer Biology Objective: MicroRNAs have been implicated in many physiological and pathological processes, including cancer

development and progression. The let-7 microRNAs are frequently downregulated in human cancers and target essential oncogenes, such as Ras. Here, we investigated the role of let-7 in multi-drug resistance of gastric cancer cells and the underlying mechanisms. Methods: The differentially expressed miRNAs between multidrug-resistant gastric cancer cell line SGC7901/VCR and its parental cell line SGC7901 were identified by miRNA profiling of these two cell lines using miRNA microarray; The results obtained by microarray profiling were validated using real-time RT-PCR analysis; The effect of let-7 on in vitro drug sensitivity of gastric cancer buy ICG-001 cells was determined by MTT assay; The putative

target genes of let-7 were predicted and validated by Western blot, RT-PCR and luciferase reporter assay; The effect of let-7 on DNA repair capacity in SGC7901/VCR cells was assessed by host cell reactivation assay. Results: Let-7a and let-7e, two members of the let-7 family, were found to be downregulated in multidrug-resistant gastric cancer cell line SGC7901/VCR compared to its parental SGC7901 cell line. In vitro drug sensitivity assay demonstrated that overexpression MCE of let-7a and let-7e sensitized SGC7901/VCR cells to anticancer drugs whereas inhibition of them conferred SGC7901 cells multidrug resistance. The downregulation of let-7a and let-7e in SGC7901/VCR cells was concurrent with the upregulation

of H-Ras protein. Enforced let-7a or let-7e expression reduced H-Ras protein level through targeting the mRNA 3′-untranslated region. Moreover, some DNA damage response genes were downregulated by let-7a and let-7e indirectly. Suppression of endogenous let-7a and let-7e increased the DNA repair capacity of SGC7901 cells and this enhancement of DNA repair capacity could be largely abrogated by introduction of dominant-negative H-Ras (A15-H-Ras) plasmids or inhibition of PI3K using PI3K inhibitors. Conclusion: Taken together, our findings suggested that let-7a and let-7e may play a role in the development of multidrug resistance in gastric cancer cells at least in part by modulation of DNA repair capacity via targeting Ras/PI3K signaling pathway. Key Word(s): 1. microRNA; 2. multidrug resistance; 3. H-Ras; 4.

Mutations, APC; 2. Beta Catenin; 3. Colorectal Cancer; 4. q-RTPCR, IHC; Presenting Author: LIN XIA Additional Authors: RUI DU, DEXIN ZHANG, XINMIN ZHOU, DAMING HDAC inhibitor FAN Corresponding Author: LIN XIA Affiliations: Xijing Hospital of Digestive Diseases & State Key Laboratory of Cancer Biology Objective: MicroRNAs have been implicated in many physiological and pathological processes, including cancer

development and progression. The let-7 microRNAs are frequently downregulated in human cancers and target essential oncogenes, such as Ras. Here, we investigated the role of let-7 in multi-drug resistance of gastric cancer cells and the underlying mechanisms. Methods: The differentially expressed miRNAs between multidrug-resistant gastric cancer cell line SGC7901/VCR and its parental cell line SGC7901 were identified by miRNA profiling of these two cell lines using miRNA microarray; The results obtained by microarray profiling were validated using real-time RT-PCR analysis; The effect of let-7 on in vitro drug sensitivity of gastric cancer Selumetinib cells was determined by MTT assay; The putative

target genes of let-7 were predicted and validated by Western blot, RT-PCR and luciferase reporter assay; The effect of let-7 on DNA repair capacity in SGC7901/VCR cells was assessed by host cell reactivation assay. Results: Let-7a and let-7e, two members of the let-7 family, were found to be downregulated in multidrug-resistant gastric cancer cell line SGC7901/VCR compared to its parental SGC7901 cell line. In vitro drug sensitivity assay demonstrated that overexpression MCE公司 of let-7a and let-7e sensitized SGC7901/VCR cells to anticancer drugs whereas inhibition of them conferred SGC7901 cells multidrug resistance. The downregulation of let-7a and let-7e in SGC7901/VCR cells was concurrent with the upregulation

of H-Ras protein. Enforced let-7a or let-7e expression reduced H-Ras protein level through targeting the mRNA 3′-untranslated region. Moreover, some DNA damage response genes were downregulated by let-7a and let-7e indirectly. Suppression of endogenous let-7a and let-7e increased the DNA repair capacity of SGC7901 cells and this enhancement of DNA repair capacity could be largely abrogated by introduction of dominant-negative H-Ras (A15-H-Ras) plasmids or inhibition of PI3K using PI3K inhibitors. Conclusion: Taken together, our findings suggested that let-7a and let-7e may play a role in the development of multidrug resistance in gastric cancer cells at least in part by modulation of DNA repair capacity via targeting Ras/PI3K signaling pathway. Key Word(s): 1. microRNA; 2. multidrug resistance; 3. H-Ras; 4.