The synergistic effect of chimeras consisting of N-terminal smac and modified KLA peptides in inducing apoptosis in breast cancer cell lines.

Drug resistance is one of the most important obstacles in effective cancer therapy triggered through various mechanisms. One of these mechanisms is caused by the upregulation of Inhibitor of Apoptosis Proteins (IAPs). IAPs, inhibit apoptosis through direct and/or indirect caspase inhibition, which themselves are antagonized by an endogenous protein called Second Mitochondrial-derived Activator of Caspases, Smac/Diablo, mediated by the presence of a tetrapeptide IAP binding motif at its N-terminus. Accordingly, Smac-based peptides are under intense investigation as anti-cancer drugs and have reached Phase 2 clinical trials, although, Smac based peptides or mimetics alone have not been effective as anti-cancer agents. On the other hand, KLA peptide has shown major toxicity against cancer cells through the induction of apoptosis. Consequently, we designed an anti-cancer chimera by fusing an octa-peptide from the N-terminus of mature Smac protein to a modified proapoptotic KLA peptide (KLAKLCKKLAKLCK) to be called Smac-KLA. This chimera, therefore, possesses both proapoptotic and anti-IAP activities. In addition, we dimerized this chimera via intermolecular disulfide bonds in order to enhance their cellular permeability. Both the Smac-KLA monomeric and dimeric peptides exhibited cytotoxic activity against both MCF-7 and MDA-MB231 breast cancer cell lines at low micromolar concentrations. Importantly, the dimerization of the chimeras enhanced their potency 2-4- fold due to higher cellular uptake.

How does caspases regulation play role in cell decisions? apoptosis and beyond.

Caspases are a family of cysteine proteases, and the key factors behind the cellular events which occur during apoptosis and inflammation. However, increasing evidence shows the non-conventional pro-survival action of apoptotic caspases in crucial processes. These cellular events include cell proliferation, differentiation, and migration, which may appear in the form of metastasis, and chemotherapy resistance in cancerous situations. Therefore, there should be a precise and strict control of caspases activity, perhaps through maintaining the threshold below the required levels for apoptosis. Thus, understanding the regulators of caspase activities that render apoptotic caspases as non-apoptotic is of paramount importance both mechanistically and clinically. Furthermore, the functions of apoptotic caspases are affected by numerous post-translational modifications. In the present mini-review, we highlight the various mechanisms that directly impact caspases with respect to their anti- or non-apoptotic functions. In this regard, post-translational modifications (PTMs), isoforms, subcellular localization, transient activity, substrate availability, substrate selection, and interaction-mediated regulations are discussed.

Opposing effects of metformin mediated mTORC1 inhibition on IRES possessing anti-apoptotic proteins in breast cancer cell lines.

Anti-diabetic drug, metformin, has attracted attentions as an anti-cancer agent due to the suppression of mTORC1 as a master switch of cell growth in various cancers. Upon mTORC1 inhibition, translation of proteins possessing IRES elements in their mRNAs still occurs in order to maintain proper cell function. Thus, inhibitor of apoptosis proteins are expected to be upregulated by mTORC1 inhibition due to the possession of IRES elements. Surprisingly, however, inhibition of mTORC1 with metformin in breast cancer cell lines of MDA-MB-231 and MCF-7, caused the downregulation of IRES-element possessing proteins of cIAP1, XIAP and Bcl-2, 24 h post-treatment. Interestingly, a shorter treatment time of 8 h, however, was accompanied by increased expression of these proteins. Importantly, inclusion of the proteasome inhibitor, Bortezomib, caused the upregulation of the tested anti-apoptotic proteins in both cell lines. These observations suggest that mTORC1 inhibition has a bifold effect; first upregulation of IRES-dependent survival proteins to prevent untimely cell death followed by an opposite effect, which is the enhanced proteosomal degradation of these protein in order to maintain a balanced response.

Site Directed Disulfide PEGylation of Interferon-ß-1b with Fork Peptide Linker.

The attachment of PEG to biopharmaceuticals has been applied for enhancement of bioavailability and improved stability. The PEG polymer is highly hydrated; thus effective attachment to inaccessible sites could be hindered. We have devised a scheme to address this issue by introducing a considerable distance between PEG and protein by addition of a linear peptide, appended to long chained reactive linkers. Second, the position of PEG conjugation directly affects biological activity. Accordingly, a disulfide bond could be considered as an ideal choice for site directed PEGylation; but reactivity of both thiol moieties to bridging reagent is critical for maintenance of protein structure. In our design, a forked structure with two arms provides essential flexibility to account for dissociation of reduced cysteines. An efficient yield for disulfide PEGylation of IFN-ß1b was attained and specificity, biophysical characterization, biological activity, and pharmacokinetics were surveyed.

Efficient synthesis, biological evaluation, and docking study of isatin based derivatives as caspase inhibitors.

ABTRACT In this paper, a new series of isatin-sulphonamide based derivatives were designed, synthesised and evaluated as caspase inhibitors. The compounds containing 1-(pyrrolidinyl)sulphonyl and 2-(phenoxymethyl)pyrrolidin-1-yl)sulphonyl substitution at C5 position of isatin core exhibited better results compared to unsubstituted derivatives. According to the results of caspase inhibitory activity, compound 20d showed moderate inhibitory activity against caspase-3 and -7 in vitro compared to Ac-DEVD-CHO (IC50 = 0.016 ± 0.002 µM). Among the studied compounds, some active inhibitors with IC50s in the range of 2.33-116.91 µM were identified. The activity of compound 20d was rationalised by the molecular modelling studies exhibiting the additional van der Waals interaction of N-phenylacetamide substitution along with efficacious T-shaped π-π and pi-cation interactions. The introduction of compound 20d with good caspase inhibitory activity will help researchers to find more potent agents.

An efficient method for recombinant production of human alpha synuclein in Escherichia coli using thioredoxin as a fusion partner.

Herein, we describe a simple and efficient approach to produce recombinant human α-synuclein (hAS) with high purity from Escherichia coli (E. coli). The cDNA for hAS was inserted into plasmid pET32a and expressed in E. coli BL21 (DE3) with an N-terminal tag containing E. coli thioredoxin (trx), followed by a histidine hexapeptide, and a tobacco etch virus (TEV) protease cleavage site (trx-6His-TEV). The fusion protein, trx-hAS, was initially released by osmotic shock treatment from the host cells and subsequently purified using a nickel affinity chromatography. A TEV protease cleavage step was performed to liberate the target protein, hAS, from the fusion partner, trx. Finally, an additional nickel affinity chromatography was performed to further purify the digested product. The yield of this method is ∼25 mg of tag-less protein (with ∼99% purity) per liter of culture volume. Reverse phase HPLC (RP-HPLC) and electrospray ionization (ESI) mass spectrometry confirmed the purity and authenticity of the purified protein. Thioflavin T (ThT) fluorescence assay, transmission electron microscopy (TEM), and circular dichroism (CD) spectroscopy demonstrated that the purified proteins form fibrils. Our protocol not only provides a convenient procedure for preparing highly pure hAS, but also requires very little specialized laboratory techniques.

Effect of glycated insulin on the blood-brain barrier permeability: An in vitro study.

Altered blood-brain barrier (BBB) permeability may contribute to pathogenesis of diabetes-related central nervous system disorders. Considering the presence of glycated insulin in plasma of type 2 diabetic patients, we hypothesized that glycated insulin could induce changes in paracellular permeability in BBB. Therefore, the authors decided to study the effect of glycated insulin on paracellular permeability in a BBB model and the change induced in insulin conformation upon glycation. In this study, the structural modification was examined by fluorescence and circular dichroism spectroscopies and dynamic light scattering. Cell proliferation and production of ROS in astrocytes and HUVEC cells were analyzed by MTT and spectrofluorometric assays, respectively. Apoptosis induction was determined and confirmed by flow cytometry and western blot analyses, respectively. The permeability was measured Lucifer yellow and FITC-Dextran. According to our results, glycated insulin presented altered conformation and more exposed hydrophobic patches than insulin. Formation of oligomeric species and advanced glycated end products (AGEs) were determined. Lower cell viability, higher apoptosis, and more ROS were detected upon treatment of cells with glycated insulin. Finally, glycated insulin led to increased Lucifer yellow and FITC-dextran transportation across the BBB model which could result from ROS producing and apoptosis-inducing activities of AGE-insulin.

Up regulation of Bax and down regulation of Bcl2 during 3-NC mediated apoptosis in human cancer cells.

BACKGROUND: Recently, we have reported the induction of apoptosis by 2-amino-4-(3-nitrophenyl)-3-cyano-7-(dimethylamino)-4H-chromene (3-NC) in HepG2, T47D and HCT116 cells with low nano molar IC50 values. In this study, anti-proliferative effects of modified 4-aryle-4H-chromenes derivatives; 2-amino-4-(3-bromophenyl)-3-cyano-7-(dimethylamino)-4H-chromene (3-BC), 2-amino-4-(3-trifluoromethylphenyl)-3-cyano-7-(dimethylamino)-4H-chromene (3-TFC) and 2-amino-4-(4,5-methylenedioxyphenyl)-3-cyano-7-(dimethylamino)-4H-chromene (4, 5-MC) were investigated in three human cancer cell lines. Compared to 3-NC none of the compounds displayed better anti-proliferative effect, although 3-BC appeared somewhat similar. Therefore 3-NC was selected for further studies. METHODS AND RESULTS: Treatment of HepG2, T47D and HCT116 cells with this compound induced apoptosis as visualized by fluorescence microscopic study of Hoechst 33258 stained cells. Induction of apoptosis was quantified by Annexin V/PI staining using flow cytometry. Western blot analysis also revealed that 3-NC down-regulated the expression of anti-apoptotic protein Bcl2 and up-regulated pro-apoptotic protein Bax, in all of the cell lines. Nonetheless, HepG2 cell line was the most responsive to 3-NC as Bax and Bcl2 showed the most dramatic up and down regulation. CONCLUSION: Our previous finding that 3-NC down regulates Inhibitor of Apoptosis Proteins (IAPs) and the present observation that Bax is upregulated and Bcl2 is down regulated upon 3-NC treatment, this chromene derivative has the potential to overcome chemotherapy resistance caused by up regulation of these proteins.

A Non-Apoptotic Pattern of Caspase-9/Caspase-3 Activation During Differentiation of Human Embryonic Stem Cells into Cardiomyocytes.

In vitro studies have demonstrated that the differentiation of embryonic stem cells (ESCs) into cardiomyocytes requires activation of caspases through the mitochondrial pathway. These studies have relied on synthetic substrates for activity measurements, which can be misleading due to potential none-specific hydrolysis of these substrates by proteases other than caspases. Hence, caspase-9 and caspase-3 activation are investigated during the differentiation of human ESCs (hESCs) by directly assessing caspase-9 and -3 cleavage. Western blot reveals the presence of the cleaved caspase-9 prior to and during the differentiation of human ESCs (hESCs) into cardiomyocytes at early stages, which diminishes as the differentiation progresses, without cleavage and activation of endogenous procaspase-3. Activation of exogenous procaspase-3 by endogenous caspase-9 and subsequent cleavage of chromogenic caspase-3 substrate i.e. DEVD-pNA during the course of differentiation confirmes that endogenous caspase-9 has the potency to recognize and activate procaspase-3, but for reasons that are unknown to us fails to do so. These observations suggest the existence of distinct mechanisms of caspase regulation in differentiation as compared to apoptosis. Bioinformatics analysis suggests the presence of caspase-9 regulators, which may influence proteolytic function under specific conditions.

Integrity of ATP binding site is essential for effective inhibition of the intrinsic apoptosis pathway by NAIP.

The importance of the ATP binding site of human Neuronal Apoptosis Inhibitory Protein (NAIP) on its ability in prevention of intrinsic apoptotic pathway was investigated. Thus, ATP binding lysine 476 of NAIP, which is located at the Nucleotide Binding Oligomerization Domain (NOD) was mutated to threonine and the effect of this mutation on autoproteolysis of procaspase-9 and the cleavage of procaspase-3 by apoptosome was investigated. Formation of apoptosome was induced by the addition of cytochrome c and dATP to lysates of HeLa cells transfected with pcDNA-NAIP or pcDNA-NAIP (K476T). Full length wild type NAIP prevented the cleavage of both procaspase-9 to caspase-9 and procaspase-3 to caspase-3. However, K476T variant of NAIP did not block autocleavage of procaspase-9 efficiently. Furthermore, cleavage pattern of procaspase-9 was altered in the presence of mutant NAIP. Interestingly no effect on the procaspase-3 cleavage by apoptosome was observed. The presence of NOD domain by itself had no effect on autocleavage of procaspase-9 yet slightly reduced the cleavage of procaspase-3 by apoptosome. Pull down experiment showed direct interaction of the NOD domain of NAIP with the CARD-NOD domain of Apoptotic Protease Activating Factor 1 (APAF-1). The physical association of these domains was confirmed by pull-down assays. These observations taken with previous findings indicate that the integrity of the NOD domain is essential for effective inhibition of procaspase-9 and procaspase-3 cleavage by the NAIP protein.

Contribution of Apaf-1 to the pathogenesis of cancer and neurodegenerative diseases.

Deregulation of apoptosis is associated with various pathologies, such as neurodegenerative disorders at one end of the spectrum and cancer at the other end. Generally speaking, differentiated cells like cardiomyocytes, skeletal myocytes and neurons exhibit low levels of Apaf-1 (Apoptotic protease activating factor 1) protein suggesting that down-regulation of Apaf-1 is an important event contributing to the resistance of these cells to apoptosis. Nonetheless, upregulation of Apaf-1 has not emerged as a common phenomenon in pathologies associated with enhanced neuronal cell death, i.e., neurodegenerative diseases. In cancer, on the other hand, Apaf-1 downregulation is a common phenomenon, which occurs through various mechanisms including mRNA hyper-methylation, gene methylation, Apaf-1 localization in lipid rafts, inhibition by microRNAs, phosphorylation, and interaction with specific inhibitors. Due to the diversity of these mechanisms and involvement of other factors, defining the exact contribution of Apaf-1 to the development of cancer in general and neurodegenerative disorders, in particular, is complicated. The current review is an attempt to provide a comprehensive image of Apaf-1's contribution to the pathologies observed in cancer and neurodegenerative diseases with the emphasis on the therapeutic aspects of Apaf-1 as an important target in these pathologies.

Restoration of MiR-34a Expression by 5-Azacytidine Augments Alimta -Induced Cell Death in Non-Small Lung Cancer Cells by Downregulation of HMG B1, A2 and Bcl-2 Pathway.

OBJECTIVE: Alimta (Pemetrexed) as an antifolate drug has been approved for the treatment of lung cancer. The aim of the present study was to investigate the combination effect of 5-Azacytidine (5-aza) and Alimta on the miR-34a and its target genes expression and induction of apoptotic cell death in non-small lung cancer A549 cells. MATERIALS AND METHODS: In this experimental study, lung cancer A549 cells were treated with various concentrations of Alimta alone and combined with 5-Aza. Then, viability was assessed by trypan blue and MTT assays. mRNA expressions were performed by real time-polymerase chain reaction (PCR) and western blot. Flow cytometry used to detect apoptotic/ necrotic cells and cell cycle arrest. RESULTS: Alimta alone reduced viability of the cells in a dose dependent manner with the half-maximal inhibitory concentration (IC50) value of 12 µM. Pretreatment of the cells with 5-aza (5 µM) induced a synergistic cytotoxic effect with IC50 of 3 µM. Sequential exposure of the cells to 5-aza and Alimta enhanced miR-34a expression and significantly downregulated HMGB1, HMGA2 and BCL-2 expressions. Also, it was associated with reduction of nuclear HMGB1 and HMGA2 content. Caspase-3 activation, HMGB1 release into extracellular space and staining of the cells with annexine V/PI suggested that 5-aza reduced late apoptotic/necrotic cell death induced by Alimta. In addition, combination of 5-aza and Alimta arrested the cells at S and sub-G1 phases and inhibited colony formation. CONCLUSION: 5-aza synergistically enhances Alimta induced apoptotic cell death through HMG proteins regulation, MIR34A gene expression and intrinsic apoptosis mechanism, providing a promising combination therapy in clinical lung cancer therapy.

The time course of Akt and ERK activation on XIAP expression in HEK 293 cell line.

The cell growth is controlled by the interaction of survival and cell growth arrest pathways as well as apoptosis mechanisms which determine the outcome of cell faith as proliferation or apoptosis. In this study, we have studied the activity of survival pathways, i.e., Akt and ERK1/2 with regard to XIAP (inhibitor of apoptosis) in serum starved and stimulated conditions. The HEK-293 cells were cultured in RPMI + 10% FBS. The cells were serum starved by switching to medium with 1% FBS for 24 h and serum stimulated by changing the medium to 10% FBS following serum starvation. The expression of p-Akt, p-ERK, Akt, ERK and XIAP was studied in various time points using western blot. The apoptosis was evaluated by DNA condensation using Hoechst 33258 and Caspase-3 assay. In serum starved condition expression of p-Akt and XIAP is very low. Serum stimulation increases p-Akt and p-ERK within 5 min and sustains a high level for 30 min. The expression of total Akt and ERK1/2 has not changed significantly for 24 h. XIAP expression starts at 6 h after serum stimulation, reaches to maximum level at 12 h and decreases to baseline within 24 h. Furthermore, serum starvation for 24 h does not induced apoptosis and DNA condensation. Taken together, the results indicate that serum activates Akt and ERK pathways earlier than XIAP expression. Furthermore, XIAP expression is low in serum starvation unlike p-ERK which suggests a survival role for ERK in serums starvation. The expression pattern of XIAP indicates induction by Akt and/or ERK activation which requires further studies.

Crystal engineering of an adenine-decavanadate molecular device towards label-free chemical sensing and biological screening.

Due to the inherent geometrical interdependencies of nucleic acid structures, the ability to engineer biosensors that rely on the specific interactions of these compounds is of considerable importance. Additionally, sensing or screening in a label-free fashion is a capability of these structures that can be readily achieved by exploiting the fluorescent component. In this work, the [AdH]6[V10O28].4(H2O) (1) supramolecular structure is introduced using adenine and decavanadate moieties that allow probing of selectivity to specific nucleic acid binding events by optical changes. The structure of (1) is an alternating organic-inorganic hybrid architecture of cationic adeninium (AdH+) ribbons and anionic decavanadate (DV)-water sheets. The luminescent screening and anticancer activity of compound (1) on the two human mammary carcinoma cell lines MDA-MB-231 and MCF7 were investigated using fluorescent microscopy and MTT assays, respectively. It was found that compound (1) is cell permeable with no toxicity below 12.5 µM concentration and moderate cytotoxicity at concentrations as high as 200 µM in human breast cancer cell lines, making it a useful tool to study the cell nucleus in real time.

Caspase-dependent apoptosis induced by two synthetic halogenated flavanones, 3',7-dichloroflavanone and 3',6-dichloroflavanone, on human breast and prostate cancer cells.

The destruction of cancer cells with chemotherapeutic agents is normally achieved through apoptosis. We previously introduced two synthetic halogenated flavanone derivatives, 3',7-dichloroflavanone (3'-7 DCF) and 3',6-dichloroflavanone (3'-6 DCF), as potential apoptosis-inducing agents. In the current study, we investigated the ability of these compounds in triggering intrinsic or/and extrinsic pathway of apoptosis in breast and prostate cancer cells. Also, the synergistic effect of 3'-7 DCF with TLR3 (Toll-like receptor 3) agonist in apoptosis induction was evaluated on PC3 and LNCaP human prostate cancer cells. The involved pathway of apoptosis in the treated cells was delineated by caspase-3 activity assay, PARP-1 (poly(ADP-ribose)polymerase-1) cleavage, and procaspase-9 cleavage as markers of the intrinsic pathway and procaspase-8 cleavage as the marker of the extrinsic pathway. With the exception of the normal cells, treatment of all cell lines with both 3'-7 DCF and 3'-6 DCF triggered the cleavage of procaspase-8 and procaspase-9. These results indicate that the intrinsic and the extrinsic pathways of apoptosis are the mechanisms of the toxicity of flavanones in these cancer cell lines. However, the cytoxicity of the compound 3'-7 DCF was not synergistic with TLR3 agonist. Interestingly, the activation of caspases-9 preceeded that of caspase-8 suggesting that the intrinsic pathway is the primary reason for apoptosis induction by the flavanones.

W323S variant of Xiap-Bir3 binds to SMAC but not caspase-9.

The ability of the wild-type XIAP BIR3 domain as well as its Trp323Ser variant in inhibition of human caspase-9, binding to AVPFVASLPN (SMAC-peptide), SMAC protein, and mature caspase-9 was investigated. In order to investigate the role of W323 on these interactions, this residue was mutated to Serine. Circular dichroism as well as thermal denaturation studies showed that W323S mutation did not hamper proper folding of the protein. The dissociation constants for the interaction of the wild type BIR3 as well as its mutant to Smac-type peptide were found to be 1.8 and 27 muM, respectively. The inhibition of and binding to caspase-9 by wild-type BIR3 and its mutant were also compared. While the wild-type protein potently inhibited the enzyme, the mutant failed to do so. The lack of caspase-9 inhibition was due to absence of interaction of the mutant BIR3 with mature caspase-9. These results indicate that Trp323 of BIR3 plays a pivotal role both in maintaining necessary conformation for caspase-9 interaction and to a lesser extent, recognition of Smac-type peptide. Moreover, decreased stability of the mutant compared with the wild type indicates that W323 is essential for maintaining the stability BIR3-Smac-peptide complex.

Mechanism of stabilization of Bacillus circulans xylanase upon the introduction of disulfide bonds.

The introduction of disulfide bonds has been used as a strategy to enhance the stability of Bacillus circulans xylanase. The transition temperature of the S100C/N148C (DS1), V98C/A152C (DS2), and A1GC/G187,C188 (cXl) in comparison to the wild type was increased by 5.0, 4.1 and 3.8 degrees C, respectively. Interestingly, a combination of two disulfide bonds of DS1 and cXl (cDS1, circular disulfide 1) led to a 12 degrees C increase in the transition temperature. Importantly, an increase in the melting point and DeltaDeltaG values of the cDS1 mutant was cooperative. These results suggest that the mechanism of stabilization by disulfide bonds under irreversible denaturation condition is achieved through: (1) a change in the rate-limiting step on the denaturation pathway; (2) destabilizing the unfolded state without affecting the relative rate constants on the denaturation pathway (like cXl mutant); and (3) or combination of the two (cDS1 mutant).

Restoration of p53 functions suppresses tumor growth of pancreatic cells with different p53 status.

Pancreatic tumor cells show a very high frequency of p53 mutation. Our aim in this study was to determine if the restoration of wild-type p53 function could be used to eliminate the tumorigenic phenotype in these cells. Pancreatic tumor cell lines, CRL1420, which contains elevated levels of mutant p53, and CRL1682, with no detectable p53 protein, were stably transfected with the exogenous wild-type p53 gene. The growth rate and tumorigenicity in nude mice of wild-type p53 expressing clones were measured. Our data showed that the expression of wild-type p53 decreased the growth rate of CRL1420 and completely suppressed its potential for tumor formation in nude mice. Moreover, the size of the tumor formed in nude mice by CRL1682 was reduced drastically. G1 arrest as a possible cause for tumor suppression was investigated by flowcytometry. Neither of the cell lines irrespective of the status of p53 was arrested at G1 in response to x-irradiation. Thus, our results provide functional evidence that the deletion or mutational inactivation of the p53 gene represents an important step in the tumorigenicity of pancreatic cancer. Furthermore, the extent of the restoration of p53 function by introduction of the p53 gene depends on both the cell type and the cell settings (in vitro or in vivo conditions).

The effect of wild type P53 gene transfer on growth properties and tumorigenicity of PANC-1 tumor cell line.

BACKGROUND: The p53 protein function is essential for the maintenance of the nontumorigenic cell phenotype. Pancreatic tumor cells show a very high frequency of p53 mutation. To determine if restoration of wild type p53 function can be used to eliminate the tumorigenic phenotype in these cells, pancreatic tumor cell lines, PANC-1 and HTB80, differing in p53 status were stably transfected with exogenous wild type p53 gene. METHODS: The transfection was performed using Polybrene/DMSO-Assisted Gene Transfer method. The wild type p53 gene integration into genomic DNA was detected by Southern blot and PCR. Furthermore, the expression of wild type p53 protein was detected in selected clones by immunohistochemistry and Western blot. RESULTS: While HTB80 cell line failed to produce a stable p53 expressing clone, the PANC-1 cells produced stable lines. Following characterization of clones, the growth rate and tumorigenicity of PANC-1 wild type p53 clones were compared to the control cells. Our data showed that the expression of wild type p53 decreased the growth rate of PANC-1 cells. It was also observed that the expression of wild type p53 in PANC-1 cells suppressed its potential for tumor formation in nude mice, completely, while the parental line leads to the formation of a relatively large tumor. CONCLUSION: Our results suggest that gene therapy based on restoration of wild type p53 protein function in pancreatic tumor cells with high amount of mutant p53 is a feasible option in pancreatic cancer treatment.

Apaf-1: Regulation and function in cell death.

Apoptosis, a form of programmed cell death, is responsible for eliminating damaged or unnecessary cells in multicellular organisms. Various types of intracellular stress trigger apoptosis by induction of cytochrome c release from mitochondria into the cytosol. Apoptotic protease activating factor-1 (Apaf-1) is a key molecule in the intrinsic or mitochondrial pathway of apoptosis, which oligomerizes in response to cytochrome c release and forms a large complex known as apoptosome. Procaspase-9, an initiator caspase in the mitochondrial pathway, is recruited and activated by the apoptosome leading to downstream caspase-3 processing. Various cellular proteins and small molecules can modulate apoptosome formation and function directly or indirectly. Despite recent progress in understanding the mitochondrial pathway of apoptosis, numerous questions such as the molecular mechanism of Apaf-1 oligomerization and caspase-9 activation remain poorly understood. In addition, reports have emerged showing non-apoptotic functions for Apaf-1. The current review summarizes the latest findings regarding structure-function relationship of Apaf-1 as well as its modifiers.