Advances in apoptosis research

Apoptosis, also called programmed cell death, has attracted great attention in recent years. After its discovery by Carl Vogt in 1842, apoptosis research was dormant for more than a century. Its rediscovery in the second half of this century, and the coining of the term apoptosis in 1972 by Kerr, Wyllie, and Currie, ignited an unparalleled interest in this field of science. The number of publications related to apoptosis has been growing exponentially every year ever since. This is mainly due to three major advances, two of which have been made recently and one that is currently seen. First, studies with the small nematode Caenorhabditis elegans have identified a number of apoptosis regulating genes—the first evidence that cell death is an active process under genetic control. Many of these genes have mammalian homologs that, like their worm counterparts, seem to regulate mammalian apoptosis. Second, elucidation of the signal transduction pathways of apoptosis has lead especially to the identification of specific death signaling molecules such as a new family of cysteine proteases, the caspases. Third, it has now become clear that many diseases are characterized by dysregulation of apoptotic programs. Many of these programs involve a family of receptors and their ligands, the death receptor/ligand family. The hope now is to interfere with apoptosis regulation in these systems and to develop new therapeutic concepts.

Cleavage of lamin A by Mch2 alpha but not CPP32: multiple interleukin 1 beta-converting enzyme-related proteases with distinct substrate recognition properties are active in apoptosis.

Although proteases related to the interleukin 1 beta-converting enzyme (ICE) are known to be essential for apoptotic execution, the number of enzymes involved, their substrate specificities, and their specific roles in the characteristic biochemical and morphological changes of apoptosis are currently unknown. These questions were addressed using cloned recombinant ICE-related proteases (IRPs) and a cell-free model system for apoptosis (S/M extracts). First, we compared the substrate specificities of two recombinant human IRPs, CPP32 and Mch2 alpha. Both enzymes cleaved poly-(ADP-ribose) polymerase, albeit with different efficiencies. Mch2 alpha also cleaved recombinant and nuclear lamin A at a conserved VEID decreases NG sequence located in the middle of the coiled-coil rod domain, producing a fragment that was indistinguishable from the lamin A fragment observed in S/M extracts and in apoptotic cells. In contrast, CPP32 did not cleave lamin A. The cleavage of lamin A by Mch2 alpha and by S/M extracts was inhibited by millimolar concentrations of Zn2+, which had a minimal effect on cleavage of poly (ADP-ribose) polymerase by CPP32 and by S/M extracts. We also found that N-(acetyltyrosinylvalinyl-N epsilon-biotinyllysyl)aspartic acid [(2,6-dimethylbenzoyl)oxy]methyl ketone, which derivatizes the larger subunit of active ICE, can affinity label up to five active IRPs in S/M extracts. Together, these observations indicate that the processing of nuclear proteins in apoptosis involves multiple IRPs having distinct preferences for their apoptosis-associated substrates.

Purification and cDNA cloning of a second apoptosis-related cysteine protease that cleaves and activates sterol regulatory element binding proteins.

We have purified from hamster liver a second cysteine protease that cleaves and activates sterol regulatory element binding proteins (SREBPs). cDNA cloning revealed that this enzyme is the hamster equivalent of Mch3, a human enzyme that is related to the interleukin 1beta converting enzyme. We call this enzyme Mch3/SCA-2. It is 54% identical to hamster CPP32/SCA-1, a cysteine protease that was earlier shown to cleave SREBPs at a conserved Asp between the basic helix-loop-helix leucine zipper domain and the membrane attachment domain. This cleavage liberates an NH2-terminal fragment of approximately 460 amino acids that activates transcription of genes encoding the low density lipoprotein receptor and enzymes of cholesterol synthesis. Mch3/SCA-2 and CPP32/SCA-I are synthesized as inactive 30-35 kDa precursors that are thought to be cleaved during apoptosis to generate active fragments of approximately 20 and approximately 10 kDa. The current data lend further support to the notion that SREBPs are cleaved and activated as part of the program in programmed cell death.

Apoptosis of nur77/N10-transgenic thymocytes involves the Fas/Fas ligand pathway.

The orphan nuclear receptor Nur77/N10 has recently been demonstrated to be involved in apoptosis of T cell hybridomas. We report here that chronic expression of Nur77/N10 in thymocytes of transgenic mice results in a dramatic reduction of CD4+CD8+ double-positive as well as CD4+CD8- and CD4-CD8+ single-positive cell populations due to an early onset of apoptosis. CD4-CD8- double-negative and CD25+ precursor cells, however, are unaffected. Moreover, nur77/N10-transgenic thymocytes show increased expression of Fas ligand (FasL), while the levels of the Fas receptor (Fas) are not increased. The mouse spontaneous mutant gld (generalized lymphoproliferative disease) carries a point mutation in the extracellular domain of the FasL gene that abolishes the ability of FasL to bind to Fas. Thymuses from nur77/N10-transgenic mice on a gld/gld background have increased cellularity and an almost normal profile of thymocyte subpopulations. Our results demonstrate that one pathway of apoptosis triggered by Nur77/N10 in double-positive thymocytes occurs through the upregulation of FasL expression resulting in increased signaling through Fas.

Tumor dormancy and cell signaling: anti-mu-induced apoptosis in human B-lymphoma cells is not caused by an APO-1-APO-1 ligand interaction.

Signal transduction initiated by crosslinking of antigen-specific receptors on T- and B-lymphoma cells induces apoptosis. In T-lymphoma cells, such crosslinking results in upregulation of the APO-1 ligand, which then interacts with induced or constitutively expressed APO-1, thereby triggering apoptosis. Here we show that crosslinking the membrane immunoglobulin on human lymphoma cells (Daudi) (that constitutively express APO-1) does not induce synthesis of APO-1 ligand. Further, a noncytotoxic fragment of anti-APO-1 antibody that blocks T-cell-receptor-mediated apoptosis in T-lymphoma cells does not block anti-mu-induced apoptosis. Hence, in B-lymphoma cells, apoptosis induced by signaling via membrane IgM is not mediated by the APO-1 ligand.

Induction of apoptosis by a cachectic-factor in murine myotubes and inhibition by eicosapentaenoic acid

Treatment of C2C12 myotubes with a tumour-derived proteolysis-inducing factor (PIF) at concentrations between 1 and 10 nM was shown to stimulate the activity of the apoptotic initiator caspases-8 and -9 and the apoptotic effector caspases-2,-3 and -6. This increased caspase activity was attenuated in myotubes pretreated with 50 μM eicosapentaenoic acid (EPA). At least part of the increase in caspase activity may be related to the increased proteasome proteolytic activity, since a caspase-3 inhibitor completely attenuated the PIF-induced increase in 'chymotrypsin-like' enzyme activity, the predominant proteolytic activity of the proteasome. However, Western blot analysis showed that PIF induced an increase in expression of the active form of caspase-3, which was also attenuated by EPA. Further Western blot analysis showed PIF increased the cytosolic content of cytochrome c, as well as expression of the pro-apoptotic protein bax but not the antiapoptotic protein bcl-2, which were both attenuated by 50 μM EPA. Induction of apoptosis by PIF in murine myotubes was confirmed by an increase in free nucleasomes formation and increased DNA fragmentation evidenced by a nucleasomal ladder typical of apoptotic cells. This process was again inhibited by pre-incubation with EPA. These results suggest that in addition to activating the proteasome, PIF induces apoptosis in C2C12 myotubes, possibly through the common intermediate arachidonic acid. Both of these processes would contribute to the loss of skeletal muscle in cancer cachexia.

Soybean lunasin mediates colon carcinogenesis by inducing apoptosis and preventing outgrowth of metastasis

Colorectal cancer (CRC) is the third most common cancer worldwide. Various factors such as age, lifestyle and dietary patterns affect the risk of having CRC. Epidemiological studies showed a chemopreventive effect of soy consumption against CRC. However, which component(s) of soybean is associated with this reduced risk is not yet fully delineated. The objective of this research was to evaluate the anti-colon cancer potential of lunasin isolated from defatted soybean flour using in vitro and in vivo models of CRC. Lunasin was isolated from defatted soybean flour by a combination of different chromatographic and ultrafiltration techniques. The anti-colon cancer potential of lunasin was determined using different human colon cancer cell lines in vitro and a CRC liver metastasis model in vivo. Lunasin caused cytotoxicity to different human colon cancer cells with an IC50 value of 13.0, 21.6, 26.3 and 61.7 µM for KM12L4, RKO, HCT-116 and HT-29 human colon cancer cells, respectively. This cytotoxicity correlated with the expression of the α5 integrin on human colon cancer cells with a correlation coefficient of 0.78. The mechanism involved in the cytotoxic effect of lunasin was through cell cycle arrest and induction of the mitochondrial pathway of apoptosis. In KM12L4 human colon cancer cells, lunasin caused a G2/M phase arrest increasing the percentage of cells at G2/M phase from 12% (PBS-treated) to 24% (treated with 10 µM lunasin). This arrest was attributed to the capability of lunasin to increase the expression of cyclin dependent kinase inhibitors p21 and p27. At 10 µM, lunasin increased the expression of p21 and p27 in KM12L4 colon cancer cells by 2.2- and 2.3-fold, respectively. Flow cytometric analysis showed that lunasin at 10 µM increased the percentage of cells undergoing apoptosis from 13.6% to 24.7%. This is further supported by fluorescence microscopic analysis of KM12L4 cells treated with 10 µM lunasin showing chromatin condensation and DNA fragmentation. The mechanism involved is through modification of proteins involved in the mitochondrial pathway of apoptosis in KM12L4 cells as 10 µM lunasin reduced the expression of the anti-apoptotic Bcl-2 protein by 2-fold and increased the expression of the pro-apoptotic proteins Bax, cytochrome c and nuclear clusterin by 2.2-, 2.1- and 2.3- fold, respectively. This led to increased expression and activity of the executioner of apoptosis, caspase-3 by 1.8- and 2.3-fold, respectively. This pro-apoptotic property of lunasin can be attributed to its capability to internalize into the cytoplasm and nucleus of colon cancer cells 24 h and 72 h after treatment, respectively. In addition, lunasin mediated metastasis of colon cancer cells in vitro by inhibiting the focal adhesion kinase activation thereby reducing expression of extracellular regulated kinase and nuclear factor kappa B and finally inhibiting migration of colon cancer cells. In KM12L4 colon cancer cells, 10 µM lunasin resulted in the reduction of phosphorylation of focal adhesion kinase and extracellular regulated kinase by 2.5-fold, resulting in the reduced nuclear translocation of p50 and p65 NF-κB subunits by 3.8- and 1.4-fold, respectively. In an in vivo model of CRC liver metastasis, daily intraperitoneal administration of lunasin at 4 mg/kg body weight resulted in the inhibition of KM12L4 liver metastasis as shown by the reduction of the number of liver metastases from 28 (PBS-treated) to 14 (lunasin-treated, P = 0.047) and reduction in tumor burden as measured by liver weight/body weight from 0.13 (PBS-treated) to 0.10 (lunasin-treated, P = 0.039). Moreover, lunasin potentiated the anti-metastatic effect of the chemotherapeutic drug oxaliplatin given at 5 mg/kg body weight twice per week. Lunasin and oxaliplatin combination resulted in a more potent inhibition of outgrowth of KM12L4 cell metastases to the liver reducing the number of liver metastases by 6-fold and reducing the tumor burden in the liver by 3-fold when compared to PBS-treated group. This can be attributed by the capability of lunasin and oxaliplatin to reduce expression of proliferating cell nuclear antigen in liver-tumor tissue as measured by immunohistochemical staining. The results of this research for the first time demonstrated the anti-colon cancer potential of lunasin isolated from defatted soybean flour which might contribute to the chemopreventive effect of soybean in CRC as seen in different epidemiological studies. In conclusion, lunasin isolated from defatted soybean flour mediated colon carcinogenesis by inducing apoptosis and preventing outgrowth of metastasis. We suggest that the results of this research serve as a basis for further study on the chemopreventive effect of lunasin against CRC and a possible adjuvant role for lunasin in therapy of patients with metastatic CRC.

Diet Carotenoid Lutein Modulates The Expression Of Genes Related To Oxygen Transporters And Decreases Dna Damage And Oxidative Stress In Mice.

Lutein (LT) is a carotenoid obtained by diet and despite its antioxidant activity had been biochemically reported, few studies are available concerning its influence on the expression of antioxidant genes. The expression of 84 genes implicated in antioxidant defense was quantified using quantitative reverse transcription polymerase chain reaction array. DNA damage was measured by comet assay and glutathione (GSH) and thiobarbituric acid reactive substances (TBARS) were quantified as biochemical parameters of oxidative stress in mouse kidney and liver. cDDP treatment reduced concentration of GSH and increased TBARS, parameters that were ameliorated in treatment associated with LT. cDDP altered the expression of 32 genes, increasing the expression of GPx2, APC, Nqo1 and CCs. LT changed the expression of 37 genes with an induction of 13 mainly oxygen transporters. In treatments associating cDDP and LT, 30 genes had their expression changed with a increase of the same genes of the cDDP treatment alone. These results suggest that LT might act scavenging reactive species and also inducing the expression of genes related to a better antioxidant response, highlighting the improvement of oxygen transport. This improved redox state of the cell through LT treatment could be related to the antigenotoxic and antioxidant effects observed.

Defective Apoptosis In Intestinal And Mesenteric Adipose Tissue Of Crohn's Disease Patients.

Crohn's disease (CD) is associated with complex pathogenic pathways involving defects in apoptosis mechanisms. Recently, mesenteric adipose tissue (MAT) has been associated with CD ethiopathology, since adipose thickening is detected close to the affected intestinal area. However, the potential role of altered apoptosis in MAT of CD has not been addressed. To evaluate apoptosis in the intestinal mucosa and MAT of patients with CD. Samples of intestinal mucosa and MAT from patients with ileocecal CD and from non-inflammatory bowel diseases patients (controls) were studied. Apoptosis was assessed by TUNEL assay and correlated with the adipocytes histological morphometric analysis. The transcriptional and protein analysis of selected genes and proteins related to apoptosis were determined. TUNEL assay showed fewer apoptotic cells in CD, when compared to the control groups, both in the intestinal mucosa and in MAT. In addition, the number of apoptotic cells (TUNEL) correlated significantly with the area and perimeter of the adipose cells in MAT. Transcriptomic and proteomic analysis reveal a significantly lower transcript and protein levels of Bax in the intestinal mucosa of CD, compared to the controls; low protein levels of Bax were found localized in the lamina propria and not in the epithelium of this tissue. Furthermore, higher level of Bcl-2 and low level of Caspase 3 were seen in the MAT of CD patients. The defective apoptosis in MAT may explain the singular morphological characteristics of this tissue in CD, which may be implicated in the pathophysiology of the disease.

Fatty Acid Synthase Inhibitors Induce Apoptosis In Non-tumorigenic Melan-a Cells Associated With Inhibition Of Mitochondrial Respiration.

The metabolic enzyme fatty acid synthase (FASN) is responsible for the endogenous synthesis of palmitate, a saturated long-chain fatty acid. In contrast to most normal tissues, a variety of human cancers overexpress FASN. One such cancer is cutaneous melanoma, in which the level of FASN expression is associated with tumor invasion and poor prognosis. We previously reported that two FASN inhibitors, cerulenin and orlistat, induce apoptosis in B16-F10 mouse melanoma cells via the intrinsic apoptosis pathway. Here, we investigated the effects of these inhibitors on non-tumorigenic melan-a cells. Cerulenin and orlistat treatments were found to induce apoptosis and decrease cell proliferation, in addition to inducing the release of mitochondrial cytochrome c and activating caspases-9 and -3. Transfection with FASN siRNA did not result in apoptosis. Mass spectrometry analysis demonstrated that treatment with the FASN inhibitors did not alter either the mitochondrial free fatty acid content or composition. This result suggests that cerulenin- and orlistat-induced apoptosis events are independent of FASN inhibition. Analysis of the energy-linked functions of melan-a mitochondria demonstrated the inhibition of respiration, followed by a significant decrease in mitochondrial membrane potential (ΔΨm) and the stimulation of superoxide anion generation. The inhibition of NADH-linked substrate oxidation was approximately 40% and 61% for cerulenin and orlistat treatments, respectively, and the inhibition of succinate oxidation was approximately 46% and 52%, respectively. In contrast, no significant inhibition occurred when respiration was supported by the complex IV substrate N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD). The protection conferred by the free radical scavenger N-acetyl-cysteine indicates that the FASN inhibitors induced apoptosis through an oxidative stress-associated mechanism. In combination, the present results demonstrate that cerulenin and orlistat induce apoptosis in non-tumorigenic cells via mitochondrial dysfunction, independent of FASN inhibition.

Familial Systemic Mastocytosis With Germline Kit K509i Mutation Is Sensitive To Treatment With Imatinib, Dasatinib And Pkc412.

Mastocytosis are myeloproliferative neoplasms commonly related to gain-of-function mutations involving the tyrosine kinase domain of KIT. We herein report a case of familial systemic mastocytosis with the rare KIT K509I germ line mutation affecting two family members: mother and daughter. In vitro treatment with imatinib, dasatinib and PKC412 reduced cell viability of primary mast cells harboring KIT K509I mutation. However, imatinib was more effective in inducing apoptosis of neoplastic mast cells. Both patients with familial systemic mastocytosis had remarkable hematological and skin improvement after three months of imatinib treatment, suggesting that it may be an effective front line therapy for patients harboring KIT K509I mutation.

Reduced Lrp6 Expression And Increase In The Interaction Of Gsk3β With P53 Contribute To Podocyte Apoptosis In Diabetes Mellitus And Are Prevented By Green Tea.

In diabetes mellitus (DM), podocyte apoptosis leads to albuminuria and nephropathy progression. Low-density lipoprotein receptor-related protein 6 (LRP6) is WNT pathway receptor that is involved in podocyte death, adhesion and motility. Glycogen synthase kinase 3 (GSK3) interaction with p53 (GSK3-p53) promotes apoptosis in carcinoma cells. It is unknown if GSK3-p53 contributes to podocyte apoptosis in DM. In experimental DM, green tea (GT) reduces albuminuria by an unknown mechanism. In the present study, we assessed the role of the GSK3β-p53 in podocyte apoptosis and the effects of GT on these abnormalities. In diabetic spontaneously hypertensive rats (SHRs), GT prevents podocyte's p-LRP6 expression reduction, increased GSK3β-p53 and high p53 levels. In diabetic SHR rats, GT reduces podocyte apoptosis, foot process effacement and albuminuria. In immortalized mouse podocytes (iMPs), high glucose (HG), silencing RNA (siRNA) or blocking LRP6 (DKK-1) reduced p-LRP6 expression, leading to high GSK3β-p53, p53 expression, apoptosis and increased albumin influx. GSK3β blockade by BIO reduced GSK3β-p53 and podocyte apoptosis. In iMPs under HG, GT reduced apoptosis and the albumin influx by blocking GSK3β-p53 following the rise in p-LRP6 expression. These effects of GT were prevented by LRP6 siRNA or DKK-1. In conclusion, in DM, WNT inhibition, via LRP6, increases GSK3β-p53 and podocyte apoptosis. Maneuvers that inactivate GSK3β-p53, such as GT, may be renoprotective in DM.

The inducing NO-vasodilation by chemical reduction of coordinated nitrite ion in cis-[Ru(NO(2))L(bpy)(2)](+) complex

The synthesis of [Ru(NO(2)) L(bpy)(2)](+) (bpy = 2,2'-bipyridine and L = pyridine (py) and pyrazine (pz)) can be accomplished by addition of [Ru(NO) L(bpy) 2](PF(6))(3) to aqueous solutions of physiological pH. The electrochemical processes of [Ru(NO2) L(bpy) 2]+ in aqueous solution were studied by cyclic voltammetry and differential pulse voltammetry. The anodic scan shows a peak around 1.00 V vs. Ag/AgCl attributed to the oxidation process centered on the metal ion. However, in the cathodic scan a second peak around-0.60 V vs. Ag/AgCl was observed and attributed to the reduction process centered on the nitrite ligand. The controlled reduction potential electrolysis at-0.80 V vs. Ag/AgCl shows NO release characteristics as judged by NO measurement with a NO-sensor. This assumption was confirmed by ESI/MS(+) and spectroelectrochemical experiment where cis-[Ru(bpy)(2)L(H(2)O)](2+) was obtained as a product of the reduction of cis-[Ru(II)(NO(2)) L(bpy)(2)](+). The vasorelaxation observed in denuded aortic rings pre-contracted with 0.1 mu mol L(-1) phenylephrine responded with relaxation in the presence of cis-[RuII(NO2) L(bpy) 2]+. The potential of rat aorta cells to metabolize cis-[RuII(NO(2)) L(bpy)(2)](+) was also followed by confocal analysis. The obtained results suggest that NO release happens by reduction of cis-[RuII(NO(2)) L(bpy)(2)](+) inside the cell. The maximum vasorelaxation was achieved with 1 x 10(-5) mol L(-1) of cis-[RuII(NO(2)) L(bpy)(2)](+) complex.

Expression of eight genes of nuclear factor-kappa B pathway in multiple myeloma using bone marrow aspirates obtained at diagnosis

Purpose: To evaluate the expression of NF-kappa B pathway genes in total bone marrow samples obtained from MM at diagnosis using real-time quantitative PCR and to evaluate its possible correlation with disease clinical features and survival. Material and methods: Expression of eight genes related to NF-kappa B pathway (NFKB1, IKB, RANK, RANKL, OPG, IL6, VCAM1 and ICAM1) were studied in 53 bone marrow samples from newly diagnosed MM patients and in seven normal controls, using the Taqman system. Genes were considered overexpressed when tumor expression level was at least four times higher than that observed in normal samples. Results: The percentages of overexpression of the eight genes were: NFKB1 0%, IKB 22.6%, RANK 15.1%, RANKL 31.3%, OPG 7.5%, IL6 39.6%, VCAM1 10% and ICAM1 26%. We found association between IL6 expression level and International Staging System (ISS) (p = 0.01), meaning that MM patients with high ISS scores have more chance of overexpression of IL6. The mean value of ICAM1 relative expression was also associated with the ISS score (p = 0.02). Regarding OS, cases with IL6 overexpression present worse evolution than cases with IL6 normal expression (p = 0.04). Conclusion: We demonstrated that total bone marrow aspirates can be used as a source of material for gene expression studies in MM. In this context, we confirmed that IL6 overexpression was significantly associated with worse survival and we described that it is associated with high ISS scores. Also, ICAM1 was overexpressed in 26% of cases and its level was associated with ISS scores.