فهرست مطالب bahram goliaei

Recently, a subpopulation of monocytes expressing Tie2 receptors has been identified, playing an important role in tumor angiogenesis. Selective depletion of Tie2-expressing monocytes in tumor-bearing mice can inhibit tumor angiogenesis. Some of these macrophages have been shown to be located near the tumor blood vessels, forming vessels in these areas paracrinely during the angiogenesis process.

This study aims to investigate the role of putative phosphorylation sites on Tie2 receptor in tumor- associated macrophages connected to human endothelial cells.

In this study, we used a series of Tie2 mutants. After transfection of tumor-associated macrophages  with these mutants, they were evaluated for physical connection using the surface plasmon resonance technique and by non-contact co-culture of these macrophages with endothelial cells.

Mutation in the tyrosine residues 1106 and 1111 had an inhibitory effect on macrophage binding to endothelial cells, resulting in deterioration of the angiogenic activity of these cells.

Tie2 receptor and its downstream molecular pathways such as AKT/PI3 have a role in the interaction of tumor-associated macrophages with human endothelial cells, directly (via physical binding) and indirectly (through secretion of factors affecting angiogenesis). This emphasize the importance of the molecular mechanisms of Tie2 receptor activation in the interactions of endothelial cells with tumor-associated macrophages and as an anti-angiogenic therapy for cancer.

Breast cancer is one of the most prevalent diseases around the world. Breast cancer patients treated with radiation may face Side effects as well as cancer recurrence. Some polyphenols exhibit antioxidant effects. Citrus and Orthosiphon Stamineus have source of methylated flavone called Sinensetin (SIN). In this research, we designation of Sinensetin as increasing radiation sensitivity.

The cytotoxic effect of Sinensetin was examined in MDA-MB-231 and T47D by MTT assay. As well as, the clonogenic ability of cells were Assessmented in the presence of Sinensetin and combination with radiation. To quantify expression alterations of apoptosis related genes, utilized Real-Time PCR method.

In a dose and time-dependent manner, Sinensetin decreased the viability of MDA-MB-231 and T47D. The survival fraction was decreased in cells treated with Sinensetin (SIN) prior to X-irradiation compared to cells treated with X-ray only. More ever, expression level of, Bcl-2, STAT3, and increased P53 via treated cells with Sinensetin (SIN) and X-ray.

Due to the results, Sinensetin (SIN) can be mentioned as a novel radiosensitizer and its effects may considered increasing apoptosis following DNA damage induced by irradiation.

Radiotherapy is a frequently used therapeutic modality for breast cancer. Dalbergin, a natural antioxidant, inhibits carcinogens and tumor progression. In the present study, we investigated the effect of Dalbergin on the response of T47D and MDA-MB-231 breast cancer cell lines to ionizing radiation. In this experimental in vitro study, doubling time of T47D and MDAMB- 231 were obtained from the growth curve. The cytotoxic effect of Dalbergin on T47D and MDA-MB-231 breast cancer cells were estimated via MTT assay. To determine the clonogenic ability, we treated T47D and MDA-MB-231 with Dalbergin for 48 h prior to irradiation, subsequent to which a colony assay was performed. Real-time polymerase chain reaction was employed to determine the gene expression level. Dalbergin inhibited proliferation of T47D and MDA-MB-231 in a time and concentration-dependent manner. Additionally, the most appropriate time for the treatment of these types of cancer cells was found to be 48 h and the drug's concentration in both cell lines was different. The IC50 values of T47D and MDA-MB-231 cells were 0.001 and 0.0001 μM, respectively. Moreover, this drug radiaosensitizes both cell lines effectively compared with the radiation only. Finally, the gene expression level of p53, Bcl-2, and STAT3 were investigated in cancer cells. Dalbergin showed apoptotic effects probably through the STAT/p53 signaling pathway. Therefore, Dalbergin could be considered as a radiosensitizer and its effects may be owing to increased cell death.

Non-clinical cardiovascular drug safety assessment is the main step in the progress of new pharmaceutical products. Cardiac drug safety testing focuses on a delayed rectifier potassium channel block and QT interval prolongation, whereas optogenetics is a powerful technology for modulating the electrophysiological properties of excitable cells.

For this purpose, the blue light-gated ion channel, channelrhodopsin-2 (ChR2), has been introduced into isolated primary neonatal cardiomyocytes via a lentiviral vector. After being subjected to optical stimulation, transmembrane potential and intracellular calcium were assessed.

Here, we generated cardiomyocytes expressing ChR2 (light-sensitive protein), that upon optical stimulation, the cardiomyocytes depolarized result from alterations of membrane voltage and intracellular calcium.

This cell model was easily adapted to a cell culture system in a laboratory, making this method very attractive for therapeutic research on cardiac optogenetics.

Human Serum Albumin (HSA) is one of the most abundant proteins in the blood vascular system which regulates the transportation of many chemical compounds and molecules. The purpose of this study is to review the studies about the effects of three groups of pesticides (Insecticides, herbicides and fungicides) on the molecular structure of HSA protein. 

This systematic review covers 35 studies of biophysical studies of the effect of pesticides on HSA protein. These papers were searched in PubMed, Science Direct, Web of Science databases and using Google Scholar search engine among those published from 1980 to 2019. 

In this study, all ethical principles were considered.

Given the close relationship between biological activities of HSA and its secondary structure, the most of the reviewed articles analyzed the secondary structures of the HSA using various biophysical methods such as Fourier Transform Infrared (FTIR), Circular Dichroism (CD) and computational analysis. In general, HSA-pesticides interactions can cause a reduction in α-helix structure and an increase in other secondary structures including β-sheet, β-anti, and random coils. In the most reports, it has been proven that the pesticides interact with HSA through hydrophobic and electrostatic interactions and hydrogen bonding. These interactions take place in the IIA subdomain (Site 1) of HSA. The binding constants of these interactions were in the range of 10 3 to 10 6 M-1.

The changes around the single important tryptophan residue of HSA (Trp-214) induce conformational deformity in the IIA subdomain of this protein which causes the loss of its native structure and leads to a decrease in free HSA concentrations which subsequently interrupt the transport of the essential compounds like drugs and hormones in the blood vascular system.

Breast cancer is an important cause of death among women. Prevention of cancer through dietary intervention has recently received increasing interest. Lately, dietary polyphenols have gained much attention for their health benefits, including anticancer properties. Dalbergin as a polyphenol is synthesized from a common neoflavene intermediate. This study aimed to examine whether dalbergin can be useful in the chemotherapy of estrogen receptor-positive T47D cell line. This experimental study was performed at the Laboratory of Biophysics and Molecular Biology, the Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran, from October 2017 to November 2019. The doubling time of T47D cells was obtained from the growth curve. The cytotoxic effect of dalbergin on T47D breast cancer cells was evaluated. To assess the clonogenic ability, T47D cells were treated with dalbergin for 48 hours and then, the colony assay was performed. A Real-Time PCR was used to determine the transcription levels of p53, Bcl-2, and STAT3 genes. The doubling time of T47D cells was 28.02 ± 4.22 hours (P < 0.05). Dalbergin decreased the viability of the T47D cell line. The half-maximal inhibitory concentration (IC50) values of dalbergin for T47D cells were found to be 1 µM in 24 hours, 0.001 µM in 48 hours, and 0.00001 µM in 72 hours of treatment (P < 0.05). In the clonogenic assay, 0.001 µM dalbergin for 48 hours could reduce the surviving fraction of T47D cells (P < 0.05). Additionally, dalbergin could change the mRNA levels of p53, Bcl-2, and STAT3 genes (P < 0.05). Our results indicated that dalbergin has some anticancer effects probably through inducing apoptosis in cancerous cells by changing mRNA levels of apoptosis-related proteins.

Impairments in cell migration processes may cause various diseases, among which cancer cell metastasis, tumor angiogenesis, and the disability of immune cells to infiltrate into tumors are prominent ones. Mathematical modeling has been widely used to analyze the cell migration process. Cell migration is a complicated process and requires statistical methods such as random walk for proper analysis. In this study, we reviewed the studies conducted on the random walk-based stochastic modeling of the eukaryotic cell migration. This statistical modeling can open some perspectives on more detailed modeling approaches and ultimately lead to more comprehensive knowledge about the biophysical and biochemical foundations of cell migration process.

Recently, 6 crystallographic structures of the pharmacologically important human serotonin transporter protein (5-HTT) were reported. In the present survey, two of these crystallographic structures and two homology models were used to study the distribution of 5-HTT’s residues based on their position and orientation. The aim here was to understand the structural and functional roles of membrane helices better in transporters and the costs/benefits of using homology models in such studies.
The membrane helical segments of 5-HTT were identified using a KD-hydropathy plot. The classification of membrane helical residues into 4 groups (Lipid-facing, Lumen-facing, Right and Left) was done using a novel method considering residue positions. Also two 3D structural models of 5-HTT were generated using MODELLER based on templates with 38% and 60% similarities.
Findings: Although the majority of hydrophobic residues in membrane helices were in the Lipid-facing cluster, a considerable percentage of them laid within the Lumen-facing cluster. In the Lipid-facing cluster, Ile, Leu, Val, Thr, Ala and Phe were the most frequent residues, respectively. Thus, their 3D positioning patterns were responsible for most of protein-lipid interactions and the functions of these interactions.
Discussion & Judging by the correlation coefficients, Lipid-facing and Right clusters are the most similar. This suggests that helices may rotate during the outward-inward conformational switch of the transporters. Our model-crystal structure comparisons demonstrate that in the case of membrane transporters, using a template with 38% similarity, results in poor modeling of the membrane helices. These findings can help us understand the structure and function of membrane helices in transporter proteins better.

Influenza is a major cause of morbidity and mortality worldwide. Each year, influenza viruses cause epidemics by evading pre-existing immunity through mutations in major surface glycoprotein hemagglutinin, which helps in attachment of the viral strain on the host cell surface. Due to high mutation rate, only currently circulating strains should be used in the vaccines.
The present study aimed at analyzing a dataset of complete amino acid sequences of HA to assess the extent of diversity among circulating strains of Iran, during years 2006 to 2013, and studying important amino acid changes as well as changes in predicted ligand binding sites that could enhance viral performance.
110 sequences from 17 provinces were downloaded, edited, and classified. The alignment of sequences and creation of phylogenetic trees and similarity matrices were done using bioinformatics software, such as MEGA6.0, BioEdit, DNAsisMAX, and DNAstar. Web-based analyses including SWISS- MODEL, Phyre2, and 3DLigandSite were used for evaluation of the second and third protein structures and prediction of ligand binding sites.
The results showed that 2009 was an important transition year, which classified the selected isolates into two different distinct groups. This shows the importance of changes made during possible mutations in the genomic structure of the virus, which have made it antigenically different from the previous years. This pandemic strain became dominant in the next years, and has been used as a standard vaccine strain from 2010 onwards.
The results of this study can shed further light on better understanding of the antigenic evolution of H1N1 influenza viruses and can be useful for epidemiological studies.

Micro RNAs (miRNAs) are a pivotal part of non-protein-coding endogenous small RNA molecules that regulate the genes involved in plant growth and development, and respond to biotic and abiotic environmental stresses posttranscriptionally.
In the present study, we report the results of a systemic search for identifi cation of new miRNAs in B. rapa using homology-based ESTs (Expressed Sequence Tags) analysis and considering a series of fi ltration criteria.
Plant mature miRNA sequences were searched in non-protein coding ESTs registered in NCBI EST database. Zuker RNA folding algorithm was used to generate the secondary structures of the ESTs. Potential sequences were candidate as miRNA genes and characterized evolutionarily only and if only they fi t some described criteria. Also, the web tool psRNATarget was applied to predict candidate B. rapa miRNA targets.
In this study, 10 novel miRNAs from B. rapa belonging to 6 miRNA families were identifi ed using EST-based homology analysis by considering a series of fi ltration criteria. All potent miRNAs appropriate fold back structure. Several potential targets with known/unknown functions for these novel miRNAs were identifi ed. The target genes mainly encode transcription factors, enzymes, DNA binding proteins, disease resistance proteins, carrier proteins and other biological processes.
MicroRNA having diverse functions in plant species growth, development and evolution by post transcriptionally regulating the levels of specifi c transcriptome so by eff ecting on their translation products. Research in miRNA led to the identifi cation of many miRNAs and their regulating genes from diverse plant species.

Cancer is the most common cause of death in the world, and it incidence has been increasing for many years in economically developed countries. Early detection of cancers greatly increases the chances for successful treatment. So finding cancers before they start to cause symptoms is a most effective treatment. Recent studies have proposed that blood plasma contains a rich source of disease biomarkers for detecting, diagnosing and monitoring diseases. While some researchers have dismissed the low molecular weight serum peptidome as biological trash, recent work using differential scanning calorimetry has indicated that the peptidome may reflect biological event and contain diagnostic biomarkers.
Differential scanning calorimetry (DSC), a highly sensitive tool for analysis of blood plasma and other biofluids has recently been reported. Louisville Bioscience, Inc. (LBIdx™), The Plasma Thermogram™ (pT™) company has made a significant breakthrough in the analysis of blood plasma using differential scanning calorimetry for clinical monitoring and diagnostic applications.
DSC analysis of plasma from diseased individuals revealed significant changes in the thermogram which are suggested to result not from changes in the concentration of the major plasma proteins but from interactions of small molecules or peptides with these proteins. The difference in plasma thermograms between healthy and disease individuals caused this method was recognized as a novel technique for disease diagnosis and monitoring.
Measurement of plasma proteins is a powerful clinical is standard medical practice which hope revolutionizes strategies for early cancer detection.

Protein flexibility, which has been referred as a dynamic behavior has various roles in proteins’ functions. Furthermore, for some developed tools in bioinformatics, such as protein-protein docking software, considering the protein flexibility, causes a higher degree of accuracy. Through undertaking the present work, we have accomplished the quantification plus analysis of the variations in the human Cyclin Dependent Kinase 2 (hCDK2) protein flexibility without affecting a significant change in its initial environment or the protein per se.
The main goal of the present research was to calculate variations in the flexibility for each residue of the hCDK2, analysis of their flexibility variations through clustering, and to investigate the functional aspects of the residues
with high flexibility variations.
Using Gromacs package (version 4.5.4), three independent molecular dynamics (MD) simulations of the hCDK2 protein (PDB ID: 1HCL) was accomplished with no significant changes in their initial environments, structures, or conformations, followed by Root Mean Square Fluctuations (RMSF) calculation of these MD trajectories. The amount of variations in these three curves of RMSF was calculated using two formulas.
More than 50% of the variation in the flexibility (the distance between the maximum and the minimum amount of the RMSF) was found at the region of Val-154. As well, there are other major flexibility fluctuations in other residues.
These residues were mostly positioned in the vicinity of the functional residues. The subsequent works were done, as followed by clustering all hCDK2 residues into four groups considering the amount of their variability with respect to flexibility and their position in the RMSF curves.
This work has introduced a new class of flexibility aspect of the proteins’ residues. It could also help designing and engineering proteins, with introducing a new dynamic aspect of hCDK2, and accordingly, for the other similar globular proteins. In addition, it could provide a better computational calculation of the protein flexibility, which is, especially important in the comparative studies of the proteins’ flexibility.

Human serum albumin (HSA) is a soluble blood protein which can bind to small molecules (such as drugs and toxins) and transfer them within the blood circulation. UV-Vis spectroscopy and FT-IR methods were used to characterize the binding properties of HSA with diazinon(the toxin of organophosphate) and to investigate the changes of protein secondary structure, respectively, in molecular level under physiological condition in two times of first and thirty five days. The binding constant (KDiazinon-HSA = 3.367) was have been calculated based UV-Vis spectroscopy data. In FT-IR method, the proportion of decrease in percentage of α-Helix on the first day was 53.97% to 51.88%, other secondary structures increased, such as Turns from 8.49% to10.21%, ß-Sheet from 13.94% to 14.81%, β-anti from 8.2% to %8.25 and r-coils from 15.4% to % 17.24. These changes for α-Helixes, Turns, ß-Sheet, β- anti and random r-coils after thirty five days were 56.7% to 47.11%, 25.3% to 29.75%, 6.93% to 10.94%, 2% to 2.83% and 9.08% to 10.86%, respectively. Since the content of protein secondary structure relates closely with its biological activity, therefore, a decrease in α-helix and increase in β-sheet structure in the presence of diazinon at high concentration means the decrease of HSA biological activity. Our results suggest that diazinon has a relatively good binding with HSA and it could cause considerable changes in various secondary structures and likely is indicative of a unfolding of protein especially for the samples in thirty five days.

Gene identification represents the first step to a better understanding of the physiological role of the underlying protein and disease pathways, which in turn serves as a starting point for developing therapeutic interventions. Familial hypercholesterolemia is a hereditary metabolic disorder characterized by high low-density lipoprotein cholesterol levels. Hypercholesterolemia is a quantitative trait that is controlled by interactions among several quantitative trait loci. Many biological data is presented in the context of biological networks and evaluation of biological networks is considered as the essential key to understanding complex biological systems. In this research, we used combination of information about quantitative trait loci of hypercholesterolemia with information of gene ontology and protein–protein interaction network for identification of genes associated with hypercholesterolemia. For this disease, we introduced 16 new genes which were in quantitative trait loci regions and were associated with the hypercholesterolemia disease in terms of gene ontology characteristics.

Accurate protein function prediction is an important subject in bioinformatics, especially where sequentially and structurally similar proteins have different functions. Malate dehydrogenase and L-lactate dehydrogenase are two evolutionary related enzymes, which exist in a wide variety of organisms. These enzymes are sequentially and structurally similar and share common active site residues, spatial patterns and molecular mechanisms. Here, we study various features of the active site cavity of 229 PDB chain entries and try to classify them automatically by various classifiers including the support vector machine, k nearest neighbour and random forest methods. The results show that the support vector machine yields the highest predictive performance among mentioned classifiers. Despite very close and conserved patterns among Malate dehydrogenases and L-lactate dehydrogenases, the SVM predicts the function efficiently and achieves 0.973 Matthew’s correlation coefficient and 0.987 F-score. The same approach can be used in other enzyme families for automatic discrimination between homologous enzymes with common active site elements, however, acting on different substrates.

Prostate cancer is one of the most widespread cancers in men and is fundamentally a genetic disease. Identifying regulators in cancer using novel systems biology approaches will potentially lead to new insight into this disease. It was sought to address this by inferring gene regulatory networks (GRNs). Moreover, dynamicalanalysis of GRNs can explain how regulators change among different conditions, suchas cancer subtypes. In our approach, independent gene regulatory networks from each prostate state were reconstructed using one of the current state-of-art reverse engineering approaches. Next, crucial genes involved in this cancer were highlighted by analyzing each network individually and also in comparison with each other. In this paper, a novel network-based approach was introduced to find critical transcription factors involved in prostate cancer. The results led to detection of 38 essential transcription factors based on hub type variation. Additionally, experimentalevidence was found for 29 of them as well as 9 new transcription factors. The results showed that dynamical analysis of biological networks may provide useful information to gain better understanding of the cell.

Prostate cancer is a serious genetic disease known as the first widespread cancer in men, yet the molecular changes required for the cancer progression is not fully understood. Availability of high-throughput gene expression data has led to the development of various computational methods for the identification of critical genes involved in the cancer.In this paper, we show that constructing co-expression networks using Y-chromosome genes provides an alternative strategy for detection of new candidate may involve in prostate cancer. In our approach, we constructed independent co-expression networks from normal and cancerous stages using an engineering approach. We next highlighted crucial genes involved in the prostate cancer by analyzing networks based on party and date hubs.Our results led to the detection of 19 critical genes related to prostate cancer which 12 of them were previously shown to be involved in this cancer. Also, essential Y chromosome genes were searched based on reconstruction of sub-networks which led to the identification of 4 experimentally established as well as 4 new Y chromosome genes may be linked putatively to prostate cancer.Correct inference of master genes whose mediate molecular changes during cancer progression is one of the major challenges in cancer genomics. In this paper, we show the role of Y chromosome genes in finding of prostate cancer susceptibility genes. Application of our approach to the prostate cancer has led to the establishment of the previous knowledge about this cancer as well as prediction of other new genes.

Lithium chloride (LiCl), a drug for bipolar disorder, has antiproliferative and apoptotic effects on certain breast cancer cell lines. This study was conducted to determine the effect of LiCl on radiosensitivity in a human breast cancer cell line in monolayer culture and the more realistic tumor model, multicellular tumor spheroid. Monolayer and spheroid cells were treated with LiCl (20 mM) for 24 hours. The clonogenic assay was used to indicate changes in survival after x-ray radiation. The percentage of apoptotic cells was determined by acridine orange/ethidium bromide double staining. The amounts of DNA damage and repair after exposure to ionizing radiation were assessed by comet assay. Mre11 mRNA level was determined by RT-PCR. GSK-3β and β-catenin protein levels were measured by Western blotting. Treatment with LiCl decreased surviving fraction at 2, 3 and 6 Gy doses of x-ray (P < 0.01). The sensitizer enhancement ratio was higher in spheroids than monolayer culture. LiCl also decreased DNA repair (P < 0.05) and Mre11 mRNA level (P < 0.01) in T47D cells. These decreases were more prominent in spheroids than monolayer culture. Treatment of T47D cells with LiCl sensitized this breast cancer cell line to ionizing radiation in monolayer and especially in the tumor-like spheroid culture. This radiosensitization was attributed, in part, to decline in DNA repair. Decrease in Mre11 mRNA level upon LiCl treatment was suggested to be an important cause for the decreased DNA repair in T47D monolayer and spheroid cells.

The physical interaction of proteins which lead to compiling them into large densely connected networks is a noticeable subject to investigation. Protein interaction networks are useful because of making basic scientific abstraction and improving biological and biomedical applications. Based on principle roles of proteins in biological function, their interactions determine molecular and cellular mechanisms, which control healthy and diseased states in organisms. Therefore, such networks facilitate the understanding of pathogenic (and physiologic) mechanisms that trigger the onset and progression of diseases. Consequently, this knowledge can be translated into effective diagnostic and therapeutic strategies. Furthermore, the results of several studies have proved that the structure and dynamics of protein networks are disturbed in complex diseases such as cancer and autoimmune disorders. Based on such relationship, a novel paradigm is suggested in order to confirm that the protein interaction networks can be the target of therapy for treatment of complex multi-genic diseases rather than individual molecules with disrespect the network.

PROSITE database contains a set of entries corresponding to protein families, which are used to identify the family of a protein from its sequence. Although patterns and profiles are developed to be very selective, each may have false positive or negative hits. Considering false positives as items that reduce the selectiveness of a pattern, then, the more selective pattern we have, a more accuracy in protein family detection we will get. In this paper, we have provided a method for improving the PROSITE patterns by reconstructing them in a manner that they not only still match to true positive hits, but also match to less false positive hits. From 973 PROSITE patterns, 283 have been improved by our method. We have applied the provided method on the PROSITE database and the improved resulting database is available at http://cbp.ut.ac.ir/iPROSITE

PROSITE database contains a set of entries corresponding to protein families, which are used to identify the family of a protein from its sequence. Although patterns and profiles are developed to be very selective, each may have false positive or negative hits. Considering false positives as items that reduce the selectiveness of a pattern, then, the more selective pattern we have, a more accuracy in protein family detection we will get. In this paper, we have provided a method for improving the PROSITE patterns by reconstructing them in a manner that they not only still match to true positive hits, but also match to less false positive hits. From 973 PROSITE patterns, 283 have been improved by our method. We have applied the provided method on the PROSITE database and the improved resulting database is available at http://cbp.ut.ac.ir/iPROSITE.

The purpose of this study was to investigate the enhanced thermal resistance mechanism of the DU145 tumor spheroid cultures as compared to the prostate carcinoma cell line's monolayer cultures. DU145 cells were cultured either as spheroids or monolayers. Cultures were treated with hyperthermia in a precision water bath (at 43°C for 60 minutes) and/or quercetin (50 and 500 μM for monolayer and spheroid cultures respectively). After hyperthermic treatment, the cell viability colony forming ability, and the expression of heat shock protein 70 (Hsp70) were examined in both culture systems. Hsp70 expression was studied using the western blot method. Our results showed that the DU145 monolayer and spheroid cell culture treatment with hyperthermia alone resulted in a marked survival inhibition. Furthermore, the spheroids showed a more significant resistance to hyperthermia compared to the monolayer cultures (p = 0.01). They also produced more Hsp70 than the monolayer cultures. Treatment of cells with quercetin reduced the Hsp70 level in both culture systems. However, with the reduced Hsp70 levels, thermal resistance of the spheroids showed a greater decrease in relation to that of the monolayers. The results suggest that the enhanced hyperthermia resistance mechanism of the spheroid cultures compared to that of the monolayer cultures can be attributed to spheroid's Hsp70 production.

Pectin is composed of complex polysaccharides that can inhibit cancer metastasis and proliferation with no evidence of toxicity. In the present study, the apoptotic and necrotic effects of pectic acid (PA) on the rat pituitary GH3/B6 tumor cells has been investigated. GH3/B6 cells were cultured in the Ham’s F12 medium enriched with 15% horse serum and 2.5% fetal bovine serum for 3 days. Then, they were treated by various amounts of PA in different periods (6, 24 and 48 hours). Bromocriptine was used as positive control and the cell viability was detected by MTT test. The nuclear morphology of cells was explored by florescent stains including acridine orange (AO)/ethidium bromide (EB). In addition, percentages of apoptotic and necrotic cells were studied with triphosphate nick-end labeling (TUNEL) assay, cell cycle analysis and propidium iodide (PI) staining. Long-term incubation with PA results in increased cell death and DNA damage as detected by MTT assay and AO/EB staining. TUNEL assay showed that PA (100 µg/ml to 1 mg/ml) could induce apoptosis in a dose-dependent manner, while higher concentrations of PA (2.5 and 5 mg/ml) induced necrosis which was confirmed by PI staining. Furthermore, cell cycle analysis indicated that PA induced sub G1 events, and DNA fragmentation was also correlated with the number of the apoptotic cells. It can be concluded that PA is responsible for apoptosis in the rat pituitary tumor cells. Therefore, one may suggest that this group of polysaccharides can be used in treatment of pituitary tumors.

Pectic acid extracted from plants increases the secretion of prolactin (PRL) when injected intravenously into ewes or fed to rats. Fragments of ewe hypophysis and lactating rabbit mammary gland incubated in vitro in the presence of pectic acid secreted more PRL and caseins compared to the controls. However, it is not known whether pectic acid directly stimulates PRL secretion in pituitary or interference of factors from hypophysis is required for this process. GH3/B6 cells, a clonal strain of rat pituitary, were cultured and incubated with pectic acid (2.5-100 µg/mL). The integrity of cells was examined under pectic acid treatment microscopically. Controls or pectic acid treated cells were assayed for their ability to produce PRL. The PRL was assayed by Western-blotting and Radioimmunoassay. pectic acid did not have any significant effect on the viability of cells. After being incubated with pectic acid, the cells started to become circular and protuberant shape. The maximum stimulation and PRL secretion occurred at 100 µg/mL concentration within 30 min of incubation with pectic acid. pectic acid could stimulate the release of PRL in GH3/B6 cells in the short-term incubation. This result suggested that pectic acid is a non-toxic agent that could directly stimulate PRL secretion in pituitary cells without any interference of hypophysis