Psyllium extracts decreased neoplastic phenotypes induced by the Ha-Ras oncogene transfected into a rat liver oval cell line

Ranitidine Loaded Biopolymer Floats: Designing, Characterization, and Evaluation

The float formulation is a strategy to improve the bioavailability of drugs by gastroretentive drug delivery system (GRDDS). A drug delivery model based on swellable and reswellable low density biopolymers has been designed to evaluate its drug release profile using ranitidine (RNT) as a model drug and formulations have been prepared utilizing 32factorial designs. The drug release (DR) data has been subjected to various kinetic models to investigate the DR mechanism. A reduction in rate has been observed by expanding the amounts of PSG and LSG parts, while an expansion has been noted by increasing the concentration of tragacanth (TG) and citric acid (CA) with an increment in floating time. The stearic acid (SA) has been used to decrease the lag time because a decrease in density of system was observed. The kinetic analysis showed that the optimized formulation (S4F3) followed zero-order kinetics and power law was found to be best fitted due to its minimum lag time and maximum floating ability. The resemblance of observed and predicted values indicated the validity of derived equations for evaluating the effect of independent variables while kinetic study demonstrated that the applied models are feasible for evaluating and developing float for RNT.

β-Sitosterol inhibits cell cycle progression of rat aortic smooth muscle cells through increases of p21cip1 protein

Abnormal proliferation of vascular smooth muscle cells (VSMCs) plays a central role in the pathogenesis of atherosclerosis. β-Sitosterol, an important phytosterol found in plant food, is known to exert antiatherosclerosis activity. However, the molecular mechanisms underlying β-sitosterol-induced antiproliferation of VSMCs were still not clear. This study demonstrated that β-sitosterol (1-20 μM) concentration-dependently inhibited proliferation of rat aortic smooth muscle cells (RASMCs) without cytotoxic effect. Flow cytometric analysis revealed that β-sitosterol arrested cell cycle progression through down-regulation of cyclin E and cyclin-dependent kinase (CDK)2 and up-regulation of p21cip1. In the β-sitosterol-treated RASMCs, the formation of the CDK2-p21cip1 complex was increased and the assayable CDK2 activity was decreased. Knockdown of the expression of p21cip1 gene prevented β-sitosterol-induced cell cycle arrest in RASMCs. In conclusion, β-sitosterol inhibited VSMC proliferation by increasing the levels of p21cip1 protein, which in turn inhibited the CDK2 activity, and finally interrupted the progress of the cell cycle.

Targeting specific cell signaling transduction pathways by dietary and medicinal phytochemicals in cancer chemoprevention

Natural phytochemicals derived from dietary sources or medicinal plants have gained significant recognition in the potential management of several human clinical conditions. Much research has also been geared towards the evaluation of plant extracts as effective prophylactic agents since they can act on specific and/or multiple molecular and cellular targets. Plants have been an abundant source of highly effective phytochemicals which offer great potential in the fight against cancer by inhibiting the process of carcinogenesis through the upregulation of cytoprotective genes that encode for carcinogen detoxifying enzymes and antioxidant enzymes. The mechanistic insight into chemoprevention further includes induction of cell cycle arrest and apoptosis or inhibition of signal transduction pathways mainly the mitogen-activated protein kinases (MAPK), protein kinases C (PKC), phosphoinositide 3-kinase (PI3K), glycogen synthase kinase (GSK) which lead to abnormal cyclooxygenase-2 (COX-2), activator protein-1 (AP-1), nuclear factor-kappaB (NF-κB) and c-myc expression. Effectiveness of chemopreventive agents reflects their ability to counteract certain upstream signals that leads to genotoxic damage, redox imbalances and other forms of cellular stress. Targeting malfunctioning molecules along the disrupted signal transduction pathway in cancer represent a rational strategy in chemoprevention. NF-κB and AP-1 provide mechanistic links between inflammation and cancer, and moreover regulate tumor angiogenesis and invasiveness, indicating that signaling pathways that mediate their activation provide attractive targets for new chemotherapeutic approaches. Thus cell signaling cascades and their interacting factors have become important targets of chemoprevention and phenolic phytochemicals and plant extracts seem to be promising in this endeavor.

Beta-sitosterol inhibits cell growth and induces apoptosis in SGC-7901 human stomach cancer cells

Beta-sitosterol is an important phytosterol found in plant food. It has been shown to have antiproliferative effects on cancers of the colon, breast, and prostate, but its effect on stomach cancer cells in vitro is unknown. Proliferation, cytotoxicity, and apoptosis in SGC-7901 human stomach cancer cells were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, clone formation, lactate dehydrogenase (LDH) leakage assay, acridine orange (AO)/ethidium bromide (EB) double staining, 4',6-diamidine-2'-phenylindole dihydrochloride (DAPI) staining, comet assay, and Western blotting. The results showed that beta-sitosterol suppresses the proliferation and induces the cell cytotoxicity of SGC-7901 stomach cancer cells in a time- and dose-dependent manner. Cells treated with different concentrations of beta-sitosterol also showed changes typical of apoptosis: morphological changes, DNA damage, increased expression of pro-caspase-3 and bax (p < 0.05), and activation of pro-caspase-3 and suppression of bcl-2 expression (p < 0.05). This study therefore revealed that beta-sitosterol significantly inhibits the growth and induces the apoptosis of SGC-7901 human stomach cancer cells in vitro. The decrease of the bcl-2/bax ratio and DNA damage may be the critical mechanisms of apoptosis induced by beta-sitosterol in SGC-7901 human stomach cancer cells.

Actin and Vimentin proteins with N-terminal deletion detected in tumor-bearing rat livers induced by intraportal-vein injection of Ha-ras-transfected rat liver cells

The introduction of the tumorigenic v-Ha-ras oncogene-transformed rat liver epithelial cells (WBras), which is deficient in gap junctional intercellular communication (GJIC), into F344 rats, induces significant formation of hepatocellular tumors. GJIC plays a major role in maintaining tissue homeostasis. Using this in vivo tumor model system, we used 2-dimensional electrophoresis with isoelectric focusing in the first dimension and SDS-PAGE in the second dimension to globally identify proteins that are uniquely expressed in the livers of WBras-treated rats as compared to the sham control. Immunoblotting was used to identify Ras and Connexin43, which were the positive and negative marker proteins, respectively, of the introduced WBras cells. As predicted, immunoblotting indicated that the whole liver of tumor-bearing animals exhibited a decreased level of Connexin43 and an increased level of Ras. Connexin43 and GJIC were expressed and functional in normal liver, but not in the tumor. In addition to these 2 markers, an additional 4 proteins exhibited decreased levels and 2 proteins exhibited increased levels in the livers of tumor-bearing animals. N-Terminal sequencing analysis was used to identify these proteins, which were glucose-regulated protein 78, 2 isoforms of heat shock protein 60, and the beta-chain of ATP synthase for the down regulated proteins, and beta-Actin with a 46 amino acid deletion from its N-terminus and Vimentin with a 71 amino acid deletion from its N-terminus for the up regulated proteins. These data offer potentially new markers of liver tumorigenicity, particularly, Vimentin. (

Beneficial health properties of psyllium and approaches to improve its functionalities

Psyllium is an excellent dietary source for both soluble and insoluble fibers and has been used in supplemental and food products for its beneficial health effects. The strong water-absorbing and gelling capacities have made it a great challenge to incorporate psyllium in foods at the level needed to claim health benefits on the label. This review is focused on the approaches to improve the functionality, sensory property, and bioactivity of psyllium. Also included is a brief summary of the health beneficial effects of psyllium, along with its possible adverse effects. The information may be useful for those in psyllium research and functional food development.

Pharmacology of gap junctions. New pharmacological targets for treatment of arrhythmia, seizure and cancer?

Intercellular communication in many organs is maintained via intercellular gap junction channels composed of connexins, a large protein family with a number of isoforms. This gap junction intercellular communication (GJIC) allows the propagation of action potentials (e.g., in brain, heart), and the transfer of small molecules which may regulate cell growth, differentiation and function. The latter has been shown to be involved in cancer growth: reduced GJIC often is associated with increased tumor growth or with de-differentiation processes. Disturbances of GJIC in the heart can cause arrhythmia, while in brain electrical activity during seizures seems to be propagated via gap junction channels. Many diseases or pathophysiological conditions seem to be associated with alterations of gap junction protein expression. Thus, depending on the target disease opening or closure of gap junctions may be of interest, or alteration of connexin expression. GJIC can be affected acutely by changing gap junction conductance or--more chronic--by altering connexin expression and membrane localisation. This review gives an overview on drugs affecting GJIC.

β-Sitosterol From Psyllium Seed Husk (Plantago ovata Forsk) Restores Gap Junctional Intercellular Communication in Ha-ras Transfected Rat Liver Cells

We purified compounds from the husks of psyllium seeds (Plantago ovata Forsk; desert Indian wheat), beginning with an ethanol extraction then followed by HP-20 and silica gel chromatography, which restored gap junctional intercellular communication (GJIC) in v-Ha-ras transfected rat liver epithelial WB-F344 cell line (WB-Ha-ras). GJIC was assessed by a scrape loading dye transfer assay. The active compound was identified as beta-sitosterol based on gas chromatography retention times and electron ionization mass spectroscopy (EI-MS) spectrum of authentic beta-sitosterol. Authentic beta-sitosterol restored GJIC in the tumorigenic WB-Ha-ras GJIC-deficient cells at a dose of 2.4 microM. In addition, a similar phytosterol, stigmasterol, also restored GJIC, albeit at a lower activity. beta-sitosterol and stigmasterol increased the level of connexin43 protein (Cx43) and restored phosphorylation of Cx43 to levels similar to the parental nontransfected cell line. We concluded that the restoration of intercellular communication in the GJIC-deficient, tumorigenic WB-Ha-ras cell line by the ethanol soluble fraction of psyllium seed husks is largely due to the presence of the phytosterol, beta-sitosterol. We discuss implications for dietary modulation of cancer by beta-sitosterol.

Function of oval cells in hepatocellular carcinoma in rats

AIM: To study oval cells pathological characteristics and relationship with the occurrence of hepatocellular carcinoma (HCC); to observe the form and structural characteristics of oval cells; to explore the expression characteristics of C-kit, PCNA mRNA and c-myc gene during the occurrence and development of HCC and the effect of ulinastatin (UTI) on C-kit and PCNA expression.

METHODS: One hundred and twenty-five SD rats fed on 3,3'-diaminobenzidine (DAB) to construct HCC models were divided into control group, cancer-inducing group and UTI intervention group. In each group, rat liver samples were collected at weeks 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22 and 24 respectively to study pathological distribution characteristics of oval cells in the process of carcinogenesis under optical microscope. Oval cells were separated by the methods of improved density gradient centrifugation and their structural characteristics were observed under optical microscope and electronic microscope respectively; the oval cells expressing C-kit and PCNA in the collected samples were observed by the methods of immunohistochemistry and image analysis and the expression of c-myc mRNA was also detected by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS: Oval cells proliferated firstly in the portal area then gradually migrated into hepatic parenchyma in the inducing group and intervention group. The oval cells distributed inside and outside the carcinoma nodes. The oval cells presented the characteristics of undifferentiated cells: a high ratio of nucleolus and cellular plasm and obvious nucleoli, rare organelle in plasm. Only a few mitochondria and endoplasmic reticulum and some villus-like apophysis on surface of cells could be seen. Cells stained with C-kit and PCNA antibody were mainly oval cells distributed in the portal area. The expression of c-myc mRNA increased with the progression of HCC. However, in the intervention group, UTI could retard its increase.

CONCLUSION: Oval cells work throughout the development of HCC, and might play important roles in this process. c-myc gene may be a kind of promoter gene of HCC, and play a key role in hepatic injury and development of HCC. UTI could retard the occurrence of HCC.