SNHG4-mediated PTEN destabilization confers oxaliplatin resistance in colorectal cancer cells by inhibiting ferroptosis.

Oxaliplatin resistance poses a significant challenge in colorectal cancer (CRC) therapy, necessitating further investigation into the underlying molecular mechanisms. This study aimed to elucidate the regulatory role of SNHG4 in oxaliplatin resistance and ferroptosis in CRC. Our findings revealed that treatment with oxaliplatin led to downregulation of SNHG4 expression in CRC cells, while resistant CRC cells exhibited higher levels of SNHG4 compared to parental cells. Silencing SNHG4 attenuated oxaliplatin resistance and reduced the expression of resistance-related proteins MRD1 and MPR1. Furthermore, induction of ferroptosis effectively diminished oxaliplatin resistance in both parental and resistant CRC cells. Notably, ferroptosis induction resulted in decreased SNHG4 expression, whereas SNHG4 overexpression suppressed ferroptosis. Through FISH, RIP, and RNA pull-down assays, we identified the cytoplasmic localization of both SNHG4 and PTEN, establishing that SNHG4 directly targets PTEN, thereby reducing mRNA stability in CRC cells. Silencing PTEN abrogated the impact of SNHG4 on oxaliplatin resistance and ferroptosis in CRC cells. In vivo experiments further validated the influence of SNHG4 on oxaliplatin resistance and ferroptosis in CRC cells through PTEN regulation. In conclusion, SNHG4 promotes resistance to oxaliplatin in CRC cells by suppressing ferroptosis through instability of PTEN, thus serves as a target for patients with oxaliplatin-base chemoresistance.

Systematic analyzing a five- miRNA panel and its diagnostic value of plasma expression in colorectal cancer.

BACKGROUND: Aberrant expression of miRNAs have been implicated in cancers, but the role of miRNAs in colorectal cancer (CRC) remains need to be elucidated. This study aimed to identify miRNAs that related to colorectal cancer (CRC) pathogenesis and determine the diagnostic value. METHODS: Three GEO datasets (GSE128449, GSE35602 and GSE49246) with 131 samples were used to screen miRNAs that differential expression between tumor and control tissues. The expression of the identified miRNAs was validated in 50 clinical tissue samples and the GSE35834 dataset. The clinical significance of these miRNAs was analyzed in the TCGA dataset and clinical tissue samples. The expression of miRNAs in tissues and plasma samples were tested by RT-PCR assay in clinical samples, and their diagnostic value was determined. RESULTS: The analysis of three GEO datasets revealed that miR-595 and miR-1237 were upregulated, while miR-126, miR-139, and miR-143 were downregulated in CRC tissues compared to control tissues. The differential expression of the five miRNAs in CRC tissues was confirmed using clinical tissue samples and GEO databases. There was no significant correlation between the TNM stage and tumor stage of CRC and any of the five miRNAs. Plasma expression of the miRNAs differed significantly between CRC and non-cancer patients, and each miRNA had moderate diagnostic value for CRC. Combining the five miRNAs provided better diagnostic potential for CRC than a single miRNA. CONCLUSIONS: This study demonstrated that five miRNAs were related to the pathogenesis of CRC, but independent of the stage of CRC; Plasma expression of these miRNAs have moderate diagnostic value, and combination of these miRNAs showed better diagnostic ability in CRC.

Construction of a long noncoding RNA-based competing endogenous RNA network and prognostic signatures of left- and right-side colon cancer.

BACKGROUND: Cancers located on the right and left sides of the colon have distinct clinical and molecular characteristics. This study aimed to explore the regulatory mechanisms of location-specific long noncoding RNAs (lncRNAs) as competing endogenous RNAs (ceRNAs) in colon cancer and identify potential prognostic biomarkers. METHOD: Differentially expressed lncRNAs (DELs), miRNAs (DEMs), and genes (DEGs) between right- and left-side colon cancers were identified by comparing RNA sequencing profiles. Functional enrichment analysis was performed for the DEGs, and a ceRNA network was constructed. Associations between DELs and patient survival were examined, and a DEL-based signature was constructed to examine the prognostic value of these differences. Clinical colon cancer tissues and Gene Expression Omnibus (GEO) datasets were used to validate the results. RESULTS: We identified 376 DELs, 35 DEMs, and 805 DEGs between right- and left-side colon cancers. The functional enrichment analysis revealed the functions and pathway involvement of DEGs. A ceRNA network was constructed based on 95 DEL-DEM-DEG interactions. Three DELs (LINC01555, AC015712, and FZD10-AS1) were associated with the overall survival of patients with colon cancer, and a prognostic signature was established based on these three DELs. High risk scores for this signature indicated poor survival, suggesting that the signature has prognostic value for colon cancer. Examination of clinical colon cancer tissues and GEO dataset analysis confirmed the results. CONCLUSION: The ceRNA regulatory network suggests roles for location-specific lncRNAs in colon cancer and allowed the development of an lncRNA-based prognostic signature, which could be used to assess prognosis and determine treatment strategies in patients with colon cancer.

Percentage of Natural Killer (NK) Cells in Peripheral Blood Is Associated with Prognosis in Patients with Gastric Cancer: A Retrospective Study from a Single Center.

BACKGROUND Natural killer (NK) cells are important for the prognosis of multiple cancers, but their prognostic value remains to be evaluated in patients with gastric cancer. Thus, this retrospective study was conducted at a single center to investigate the association between percentage of NK cells in the peripheral blood and prognosis in patients with gastric cancer. MATERIAL AND METHODS The data of 180 gastric cancer patients were collected. Univariate and multivariate Cox regression models were applied to screen candidate prognostic factors. A time-dependent receiver operating characteristic curve was employed to evaluate the ability of NK cells as a prognostic marker. Furthermore, we determined the correlation between the NK cells percentage and other parameters and their clinical significance. RESULTS Patients with a higher percentage of NK cells survived longer than those with a lower percentage of NK cells. Cox analysis revealed that NK cells could be used as an independent indicator for patients with gastric cancer. The percentage of NK cells was positively correlated with lymphocyte count and albumin, but was negatively correlated with CA125 and neutrophil-lymphocyte ratio. The area under the curve for NK cells in predicting the 5-year survival rate for gastric cancer was 0.792. This increased to 0.830 upon combining NK cells with neutrophil-lymphocyte ratio. Patients at early T, N, and clinical stages possessed a significantly higher percentage of NK cells compared to those at advanced T, N, and clinical stages of gastric cancer. CONCLUSIONS Our results suggest that a higher percentage of NK cells predicts is associated with longer survival of gastric cancer patients and could serve as an independent prognostic biomarker.

Prognostic value of peripheral blood natural killer cells in colorectal cancer.

BACKGROUND: The association between natural killer (NK) cells and survival in colorectal cancer (CRC) patients remains controversial. This study aimed to clarify the prognostic value of peripheral blood NK cells in CRC patients. METHODS: A total of 447 CRC patients who underwent radical surgery and chemotherapy were retrospectively analyzed. Cox regression analyses were used to identify independent prognostic indicators. Correlation between NK cell percentage and other clinicopathological features (gender, age, histological grade, tumor stage, immune cells, and inflammatory indicators) was analyzed. The prognostic values of the combinations of NK cell percentage and other clinicopathological features were also determined. RESULTS: Multivariate Cox regression analysis revealed that NK cell percentage in the peripheral blood was an independent prognostic indicator in CRC patients. A higher percentage of NK cells indicated a longer survival time than a lower percentage. NK cell percentage was positively correlated to the T and B lymphocyte counts and negatively correlated to the patients' age and albumin levels. With an area of 0.741 under a receiver operating characteristic curve, NK cells have a moderate predictive value for 3rd-year survival in CRC. This area increased to 0.851 by combining NK cell percentage with the B lymphocyte count. Elderly patients and those at an advanced clinical stage presented a lower percentage of NK cells than younger patients and those at an early clinical stage. CONCLUSIONS: This study demonstrated that NK cells in the blood were an independent predictor of survival in CRC patients, and the combined count of NK cells and B lymphocytes could increase the prognostic value.

Impact of primary colorectal Cancer location on the KRAS status and its prognostic value.

BACKGROUND: Colorectal cancer (CRC) originating from the right-sided or left-sided colon is distinct clinicopathological entity. The KRAS status and its prognostic value in CRC remain controversial. This study aimed to investigate the association of KRAS status with clinicopathological features and prognostic value in CRC. METHODS: 178 colon cancer and 145 rectal cancer patients were enrolled. KRAS mutation test was performed on paraffin-embedded tumor samples using PCR methods. The colon cancer was divided into right-sided colon cancer (RCC) and left-sided colon cancer (LCC). Studies that reported the association of KRAS mutation with CRC clinical features and prognosis in databases were searched prior to 2018. The data of the present study was combined with the data of published studies using meta-analysis methods. RESULTS: No significant difference between colon cancer and rectal cancer regarding the KRAS status. The KRAS mutation was much frequent in RCC than in LCC (p = 0.010). 17 studies with 11,385 colon cancer patients were selected, the pooled results of our data and previous published data showed that KRAS mutation was more frequent in RCC compared with in LCC (p < 0.01); KRAS mutation was not associated with the prognosis in RCC patient; however, KRAS mutation indicated a poor prognosis in LCC patients compared with KRAS wild type (p < 0.01). CONCLUSION: KRAS status has no difference between colon cancer and rectal cancer. KRAS mutation was more frequent in RCC than in LCC, and associated with a poor prognosis in LCC patients, but not in RCC patients.

Synergistic Effects of Fruquintinib Combined with Immune Checkpoint Inhibitors on Metastatic Colorectal Cancer.

BACKGROUND: Fruquintinib has received approval for the management of patients with chemotherapy-resistant metastatic colorectal cancer (mCRC). However, combination of fruquintinib with immune checkpoint inhibitors (ICIs) is yet to be extensively studied. This study aims to assess the clinical efficacy, safety, and prognostic indicators of treatment regimen combining fruquintinib with ICIs in mCRC patients. METHODS: We analyzed data from mCRC patients who were administered fruquintinib either as a monotherapy or in conjunction with ICIs following conventional chemotherapy. Parameters such as the objective response rate (ORR), disease control rate (DCR), overall survival (OS), progression-free survival (PFS), and incidence of adverse events were meticulously evaluated. Furthermore, the relationship between blood markers and patient prognosis was examined. RESULTS: A total of 72 mCRC patients were included in this study, with a median observation period of 48 months, 19 were treated with fruquintinib alone, while 53 received a combination therapy involving fruquintinib and ICIs. The combined therapy group exhibited superior ORR and DCR compared to the fruquintinib monotherapy group. Additionally, significant improvements in OS and PFS were observed in the combined treatment group. The occurrence of adverse events was generally manageable and well-tolerated across both groups, with no significant difference in incidence rates. Notably, albumin levels were identified as a prognostic marker for PFS and OS in the univariate Cox regression analysis. CONCLUSIONS: The combination of fruquintinib with ICIs demonstrated enhanced clinical efficacy and improved survival outcomes compared to fruquintinib monotherapy in mCRC patients. The safety of the combination regimen was deemed manageable and acceptable.

Clinical Significance and Prognostic Value of the Maximum Standardized Uptake Value of 18F-Flurodeoxyglucose Positron Emission Tomography-Computed Tomography in Colorectal Cancer.

BACKGROUND: The role of 18F-flurodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET/CT) in colorectal cancer (CRC) remains unclear. This study aimed to explore the association of the maximum standardized uptake value (SUVmax), a parameter of 18F-FDG PET/CT, with KRAS mutation, the Ki-67 index, and survival in patients with CRC. METHODS: Data of 66 patients with CRC who underwent 18F-FDG PET/CT was retrospectively collected in our center. The clinical significance of the SUVmax in CRC and the association of the SUVmax with KRAS mutation and the Ki-67 index were determined. A meta-analysis was conducted by a systematic search of PubMed, Web of Science, and CNKI databases, and the data from published articles were combined with that of our study. The association of the SUVmax with KRAS mutation and the Ki-67 index was determined using the odds ratio to estimate the pooled results. The hazard ratio was used to quantitatively evaluate the prognosis of the SUVmax in CRC. RESULTS: By analyzing the data of 66 patients with CRC, the SUVmax was found not to be related to the tumor-node-metastasis stage, clinical stage, sex, and KRAS mutation but was related to the tumor location and nerve invasion. The SUVmax had no significant correlation with the tumor biomarkers and the Ki-67 index. Data of 17 studies indicated that the SUVmax was significantly increased in the mutated type compared with the wild type of KRAS in CRC; four studies showed that there was no remarkable difference between patients with a high and low Ki-67 index score regarding the SUVmax. Twelve studies revealed that the SUVmax had no significant association with overall survival and disease-free survival in CRC patients. CONCLUSIONS: Based on the combined data, this study demonstrated that the SUVmax of 18F-FDG PET/CT was different between colon and rectal cancers and associated with KRAS mutation but not the Ki-67 index; there was no significant association between the SUVmax and survival of patients with CRC.

Systematic Analysis of the Clinical Significance of Hyaluronan-Mediated Motility Receptor in Colorectal Cancer.

Background: The role of hyaluronan-mediated motility receptor (HMMR) in colorectal cancer (CRC) remains unclear. The present study aimed to explore the association of HMMR with the development and prognosis of CRC using sequence datasets, clinical tissues, blood samples, and cell lines. Methods: CRC datasets were downloaded from TCGA and GEO databases. Forty CRC tissue samples, 120 CRC blood samples, and 100 healthy controls were collected. Four CRC cell lines (HCT116, HT-29, LoVo, and SW480) and one normal human colon mucosal epithelial cell line (NCM460) were cultured. RT-qPCR was used to determine the expression of HMMR in the tissues and cell lines. ELISA was used to measure HMMR levels in the blood samples. Results: The expression of HMMR was significantly increased in CRC tissues than in corresponding adjacent tissues based on TCGA and GEO datasets, and clinical CRC tissues. No associations were found between the expression of HMMR and the TNM stage or other clinical parameters. The expression of HMMR varied in different CRC cell lines. The blood levels of HMMR tended to be higher in patients with CRC than in healthy controls. TCGA and GEO datasets showed inconsistent results regarding the association of HMMR expression with the survival of patients with CRC. Conclusion: The expression of HMMR is increased in CRC tissues but not in the blood. The expression of HMMR is independent of CRC development and has no prognostic significance in patients with CRC.

Diagnostic and prognostic value of plasma heat shock protein 90alpha in gastric cancer.

BACKGROUND: The role of plasma heat shock protein 90alpha (Hsp90α) in gastric cancers remains unclear. This study aimed to clarify the diagnostic and prognostic value of plasma Hsp90α in gastric cancer. METHODS: Data regarding 976 gastric cancer, 50 gastric inflammatory diseases, and 100 healthy controls were collected. Plasma Hsp90α levels in gastric cancer were compared to those in controls. Its correlation with tumor biomarkers and immune cells was examined. The association of plasma Hsp90α with clinical features and the diagnostic and prognostic value in gastric cancer were also determined. RESULTS: Plasma Hsp90α levels were remarkably increased in gastric cancer, compared to those in gastric inflammatory diseases and healthy controls. Moreover, plasma Hsp90α was correlated with CEA, CA125, CA153, CA199, T cells, Th/Ts ratio, and B cells. Plasma Hsp90α was also associated with the metastasis stage. Multivariate logistic regression analysis revealed that Hsp90α, B cells, and T cells were significantly associated with gastric cancer. Plasma Hsp90α has a moderate diagnostic value, which increased when combined with B cell, T cells. Finally, plasma Hsp90α was not associated with the survival of gastric cancer patients. CONCLUSION: Plasma Hsp90α was elevated in gastric cancer and correlated with tumor biomarkers and immune cells. Plasma Hsp90α was associated with the metastasis stage and had moderate diagnostic performance but little prognostic value in gastric cancer.

Clinical Significance and Prognostic Value of miR-28-5p in Colon Cancer.

BACKGROUND: The association of miR-28-5p with colon cancer remains to be elucidated. This study aimed to determine the clinical significance and prognostic value of miR-28-5p in colon cancer. METHODS: We retrospectively analyzed the data of miR-28-5p in colon adenocarcinoma data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO), and the data was divided into cancer group and normal group, respectively. Forty colon cancer tissues and adjacent normal tissues were collected and tested by qRT-PCR methods. The difference of the miR-28-5p expression between colon cancer and normal tissues was compared. The clinical significance of miR-28-5p in colon cancer and the association with the survival were determined. The predictive value of miR-28-5p in clinical features was determined using receiver operating characteristic curve. The target genes of miR-28-5p were identified, and the functional of target genes was performed using bioinformatics analysis. RESULTS: : The expression of miR-28-5p was increased in colon cancer tissues compared with normal controls (p = 0.037). The expression of miR-28-5p was significantly increased in tissues with distant metastases compared with that without distant metastases (p = 0.026). Patients with high expression of miR-28-5p have a shorter survival time than those with low expression (p = 0.004). Cox analysis showed that miR-28-5p was an independent predictor for the survival of patients (p = 0.014). Combination of miR-28-5p with TNM stage and clinical stage can improve the prognostic value for the patients (p < 0.05). miR-28-5p has a moderate predictive value in predicting the TNM stage and clinical stage (T stage: AUC = 0.515; N stage: AUC = 0.523, M stage: AUC = 0.572; clinical stage: AUC = 0.539). 711 potential target genes of miR-28-5p were screened; their function and pathways were identified. CONCLUSIONS: : This study demonstrated that miR-28-5p was increased in colon cancer and can be an independent indicator for the overall survival in patients with colon cancer.

Genome-wide analysis to identify a novel distant metastasis-related gene signature predicting survival in patients with gastric cancer.

This study designed to identify a potential novel distant metastasis-related gene (DMGs) signature that predicting prognosis in patients with gastric cancer. DMGs was screened by overlapping the differentially expressed genes between M0 and M1 stage, and between tumor and adjacent normal tissue of gastric cancer by analyzing The Cancer Genome Atlas (TCGA) dataset. There were 83 DMGs were identified, the integrative analysis revealed these DMGs were involved in several biological process and pathway. A six-DMGs prognostic signature was developed based on the risk score obtained from Cox analysis. Patients with low risk score presented significantly shorter survival time. This prognostic signature has a moderate predictive value for the overall survival in gastric cancer patients, with an area under curve of 0.604. The DMGs prognostic signature also significantly associated with the overall survival of gastric cancer patients, and showed a better performance for predicting prognosis than traditional clinical indicators. The joint effect of risk score with clinical features could remarkably increased the predictive value as compared with single variable. The results from 60 gastric cancer tissues verified the prognostic value of the six-DMGs prognostic signature. In conclusions, the present study identified a novel six-DMGs prognostic signature that could serve as a biomarker for the prognosis prediction of patients with gastric cancer.

The PPARalpha/gamma dual agonist chiglitazar improves insulin resistance and dyslipidemia in MSG obese rats.

1. The aim of this study was to investigate the capacity of chiglitazar to improve insulin resistance and dyslipidemia in monosodium L-glutamate (MSG) obese rats and to determine whether its lipid-lowering effect is mediated through its activation of PPARalpha. 2. Chiglitazar is a PPARalpha/gamma dual agonist. 3. The compound improved impaired insulin and glucose tolerance; decreased plasma insulin level and increased the insulin sensitivity index and decreased HOMA index. Euglycemic hyperinsulinemic clamp studies showed chiglitazar increased the glucose infusion rate in MSG obese rats. 4. Chiglitazar inhibited alanine gluconeogenesis, lowered the hepatic glycogen level in MSG obese rats. Like rosiglitazone, chiglitazar promoted the differentiation of adipocytes and decreased the maximal diameter of adipocytes. In addition, chiglitazar decreased the fibrosis and lipid accumulation in the islets and increased the size of islets. 5. Chiglitazar reduced plasma triglyceride, total cholesterol (TCHO), nonesterified fatty acids (NEFA) and low density lipoprotein-cholesterol levels; lowered hepatic triglyceride and TCHO contents; decreased muscular NEFA level. Unlike rosiglitazone, chiglitazar showed significant increase of mRNA expression of PPARalpha, CPT1, BIFEZ, ACO and CYP4A10 in the liver of MSG obese rats. 6. These data suggest that PPARalpha/gamma coagonist, such as chiglitazar, affect lipid homeostasis with different mechanisms from rosiglitazone, chiglitazar may have better effects on lipid homeostasis in diabetic patients than selective PPARgamma agonists.

Experimental treatment of complications in alloxan diabetic rats with alpha-glucosidase inhibitor from the Chinese medicinal herb ramulus mori.

AIM: To assess the effects of the alpha-glucosidase inhibitor Sangzhi (Ramulus mori, SZ) on the relief of diabetic symptoms of hyperglycemia and the prevention of its late complications in alloxan diabetic rats with high-calorie chow. METHODS: The aqueous extract of Sangzhi was given orally to alloxan diabetic rats for 15 days. The hyperglycemic symptoms were observed. The blood glucose, lipid levels and the nephrotic representations were measured. RESULTS: When alloxan diabetic rats on high-calorie chow were treated with SZ, the hyperglycemic symptoms were improved, the blood lipid levels were improved, the ratio of kidney over body weight and the blood N-acetyl-beta-D-glucosaminidase (NAG) activity were lowered. The degree of renal pathological changes was significantly reduced. CONCLUSION: SZ may be useful for treating diabetes and its complications.

[Ameliorations of pioglitazone on insulin resistance in spontaneous IGT-OLETF rats].

AIM: To investigate the ameliorations of pioglitazone, a member of the thiazolidinedione group of antidiabetic agents, on insulin resistance in spontaneous OLETF rats with impaired glucose tolerance (IGT-OLETF). METHODS: One group of IGT-OLETF rats was orally administered pioglitazone at the dose of 20 mg x kg(-1) (qd) for 2 weeks. Another group was given the same volume of solvent as control. Glucose tolerance and insulin tolerance were tested, and blood glucose concentrations, insulin levels and lipids in serum, liver and muscle were determined. Insulin sensitive index (ISI) was calculated by the reciprocal of fasting blood glucose times fasting insulin. RESULTS: Pioglitazone was shown to markedly enhance the glycemic response to exogenous insulin (0. 4 x kg(-1), sc) in the model. The falls of blood glucose at 40 and 90 min in the insulin tolerance test were augmented by 70% and 158% in the treated group than the control. The serum insulin levels were significantly decreased and the ISI nearly normalized after treatment. Pioglitazone also lowered the serum TG and FFA levels and the lipids in liver and muscle. No effect was found on the expression of leptin in epididymal adipose tissues and on the activity of GFAT, a key enzyme in hexosamine biosynthesis pathway (data were not shown). CONCLUSION: Pioglitazone can improve the insulin resistance state in IGT-OLETF rats. Correction of lipid disorder may be associated with it.

[Effects of conjugated linoleic acid on obese MSG mice with insulin resistance].

AIM: To study the effect of conjugated linoleic acid (CLA) on obese MSG mice with insulin resistance. METHODS: About four months old, obese MSG mice with insulin resistance were divided into control, CLA and rosiglitazone groups and drugs were administrated ig once a day. Body weights were recorded regularly, insulin and glucose tolerance were tested. In addition, serum insulin and TNF-alpha concentrations in serum and fat tissues were determined. RESULTS: CLA was shown to reduce the body weight and fat weight in MSG mice, but can not improve the abnormal insulin and glucose tolerance in these mice. Indeed, the serum insulin and TNF-alpha concentrations in the fat tissues of the group treated with CLA were higher than those in the models and the insulin sensitivity index was significantly lower than that in the model mice. CONCLUSION: CLA can reduce the body weight of MSG mice, but can not improve the insulin resistance in these mice.

Association of Helicobacter pylori with elevated blood ammonia levels in cirrhotic patients: a meta-analysis.

PURPOSE: The association between Helicobacter pylori (H. pylori) and blood ammonia levels in cirrhotic patients is controversial. We aimed to clarify this controvercy by performing a meta-analysis of published studies. MATERIALS AND METHODS: We searched PubMed, EMBASE and Cochrane library for studies which explored the association between H. pylori and blood ammonia levels in cirrhotic patients before May 2012. Six cohort studies involved in 632 H. pylori positive and 396 H. pylori negative cirrhotic patients were eligible for our analysis. The summary estimates were presented as standard means differences (SMD) and 95% confidence intervals (CI) from individual studies. RESULTS: Overall, there was significant association between H. pylori infection and the elevated blood ammonia levels in cirrhotic patients (SMD=0.34, 95% CI=0.21-0.47, I²=42.1%). Sensitivity analysis further confirmed this association. Subgroup analysis showed that the association was found only in Asian ethnicity, but not in Caucasian ethnicity. CONCLUSION: H. pylori infection is associated with elevated blood ammonia levels in cirrhotic patients, and more large scale studies and stratify analysis are warranted in order to further evaluate this association.

Pioglitazone can ameliorate insulin resistance in low-dose streptozotocin and high sucrose-fat diet induced obese rats.

AIM: To investigate the effect of the peroxisome proliferator-activator receptor (PPAR)-gamma agonist, pioglitazone, on insulin resistance in low-dose streptozotocin and high sucrose-fat diet induced obese rats. METHODS: Normal female Wistar rats were injected intraperitoneally with low-dose streptozotocin (STZ, 30 mg/kg) and fed with a high sucrose-fat diet for 8 weeks. Pioglitazone (20 mg/kg) was administered orally to the obese and insulin-resistant rats for 28 d. Intraperitoneal glucose tolerance tests, insulin tolerance tests and gluconeogenesis tests were carried out over the last 14 d. At the end of d 28 of the treatment, serums were collected for biochemical analysis. Glucose transporter 4 (GLUT4) and insulin receptor substrate-1 (IRS-1) protein expression in the liver and skeletal muscle were detected using Western blotting. RESULTS: Significant insulin resistance and obesity were observed in low-dose STZ and high sucrose-fat diet induced obese rats. Pioglitazone (20 mg/kg) treatment significantly decreased serum insulin, triglyceride and free fatty acid levels, and elevated high density lipoprotein-cholesterol (HDL-C) levels. Pioglitazone also lowered the lipid contents in the liver and muscles of rats undergoing treatment. Gluconeogenesis was inhibited and insulin sensitivity was improved markedly. The IRS-1 protein contents in the liver and skeletal muscles and the GLUT4 contents in skeletal muscle were elevated significantly. CONCLUSION: The data suggest that treatment with pioglitazone improves insulin sensitivity in low-dose STZ and high sucrose-fat diet induced obese rats. The insulin sensitizing effect may be associated with ameliorating lipid metabolism, reducing hyperinsulinemia, inhibiting gluconeogenesis, and increasing IRS-1 and GLUT4 protein expression in insulin-sensitive tissues.