Caspase-3 is dually regulated by apoptogenic factors mitochondrial release and by SAPK/JNK metabolic pathway in leukemic cells exposed to etoposide-ionizing radiation combined treatment

β1 integrin- and JNK-dependent tumor growth upon hypofractionated radiation

Radiation therapy is an effective cancer treatment modality although tumors invariably become resistant. Using the transgenic adenocarcinoma of mouse prostate (TRAMP) model system, we report that a hypofractionated radiation schedule (10 Gy/day for 5 consecutive days) effectively blocks prostate tumor growth in wild type (β1^wt /TRAMP) mice as well as in mice carrying a conditional ablation of β1 integrins in the prostatic epithelium (β1^pc-/- /TRAMP). Since JNK is known to be suppressed by β1 integrins and mediates radiation-induced apoptosis, we tested the effect of SP600125, an inhibitor of c-Jun amino-terminal kinase (JNK) in the TRAMP model system. Our results show that SP600125 negates the effect of radiation on tumor growth in β1^pc-/- /TRAMP mice and leads to invasive adenocarcinoma. These effects are associated with increased focal adhesion kinase (FAK) expression and phosphorylation in prostate tumors in β1^pc-/- /TRAMP mice. In marked contrast, radiation-induced tumor growth suppression, FAK expression and phosphorylation are not altered by SP600125 treatment of β1^wt /TRAMP mice. Furthermore, we have reported earlier that abrogation of insulin-like growth factor receptor (IGF-IR) in prostate cancer cells enhances the sensitivity to radiation. Here we further explore the β1/IGF-IR crosstalk and report that β1 integrins promote cell proliferation partly by enhancing the expression of IGF-IR. In conclusion, we demonstrate that β1 integrin-mediated inhibition of JNK signaling modulates tumor growth rate upon hypofractionated radiation.

HuR-targeted small molecule inhibitor exhibits cytotoxicity towards human lung cancer cells

Human antigen (Hu) R is an RNA-binding protein whose overexpression in human cancer correlates with aggressive disease, drug resistance, and poor prognosis. HuR inhibition has profound anticancer activity. Pharmacologic inhibitors can overcome the limitations of genetic inhibition. In this study, we examined the antitumor activity of CMLD-2, a small-molecule inhibitor directed against HuR, using non-small cell lung cancer (NSCLC) as a model. CMLD-2 efficacy was tested in vitro using H1299, A549, HCC827, and H1975 NSCLC cells and MRC-9 and CCD-16 normal human fibroblasts. Treatment of NSCLC cells with CMLD-2 produced dose-dependent cytotoxicity, caused a G1 phase cell-cycle arrest and induced apoptosis. CMLD-2 decreased HuR mRNA and the mRNAs of HuR-regulated proteins (Bcl2 and p27) in tumor cells. Additionally, reduction in the expression of HuR, Bcl2, cyclin E, and Bcl-XL with increased expression of Bax and p27 in CMLD-2-treated NSCLC cells were observed. CMLD-2-treated normal cells, HuR-regulated mRNAs and proteins albeit showed some reduction were less compared to tumor cells. Finally, CMLD-2 treatment resulted in greater mitochondrial perturbation, activation of caspase-9 and -3 and cleavage of PARP in tumor cells compared to normal cells. Our proof-of concept study results demonstrate CMLD-2 represents a promising HuR-targeted therapeutic class that with further development could lead to advanced preclinical studied and ultimately for lung cancer treatment.

Regulation of Cancer Cell Responsiveness to Ionizing Radiation Treatment by Cyclic AMP Response Element Binding Nuclear Transcription Factor

Cyclic AMP response element binding (CREB) protein is a member of the CREB/activating transcription factor (ATF) family of transcription factors that play an important role in the cell response to different environmental stimuli leading to proliferation, differentiation, apoptosis, and survival. A number of studies highlight the involvement of CREB in the resistance to ionizing radiation (IR) therapy, demonstrating a relationship between IR-induced CREB family members' activation and cell survival. Consistent with these observations, we have recently demonstrated that CREB and ATF-1 are expressed in leukemia cell lines and that low-dose radiation treatment can trigger CREB activation, leading to survival of erythro-leukemia cells (K562). On the other hand, a number of evidences highlight a proapoptotic role of CREB following IR treatment of cancer cells. Since the development of multiple mechanisms of resistance is one key problem of most malignancies, including those of hematological origin, it is highly desirable to identify biological markers of responsiveness/unresponsiveness useful to follow-up the individual response and to adjust anticancer treatments. Taking into account all these considerations, this mini-review will be focused on the involvement of CREB/ATF family members in response to IR therapy, to deepen our knowledge of this topic, and to pave the way to translation into a therapeutic context.

The Differential Expression of Galectin-1 and Galectin-3 in Normal Lymphoid Tissue and Non-Hodgkin's and Hodgkin's Lymphomas

The WHO classification of lymphomas was established on the basis of clinical, morphological, immunohistochemical and genetic criteria. However, each entity displays its own spectrum of clinical aggressiveness. Treatment success varies widely and is not predictable. Since galectins are involved in oncogenesis and the physiology of immune cells, we investigated whether galectin-1 and galectin-3 immunohistochemical expression could differ in 25 normal lymphoid tissues, 42 non-Hodgkin's and 14 Hodgkin's lymphomas. Immunohistochemical galectin expression was submitted to semi-quantitative and quantitative (computer-assisted microscopy) evaluations. This study is completed by an analysis (by means of quantitative RT-PCR) of galectin-3 mRNA expression in 3 normal lymph nodes, 3 follicular lymphomas (FLs) and 3 diffuse large B-cell lymphomas (DLBCLs). The data show that in normal lymphoid tissue, lymphocytes do not express galectin-1 and rarely express galectin-3. In contrast, galectin-3 was expressed in 8 of the 16 DLBCL cases and in 1 of the 8 FL cases. Furthermore, galectin-3 mRNA was expressed 3-times more in the DLBCLs than in the FLs. While the blood vessel walls of the lymphomas expressed galectin-1, the vessel walls of normal lymphoid tissues did not. This expression of galectin-1 in blood vessel walls was correlated with vascular density. The present study thus shows that DLBCL can be distinguished from normal lymphoid tissue and other lymphomas on the basis of galectin-3 expression.

CD40-Dependent Activation of Phosphatidylinositol 3-Kinase/Akt Pathway Inhibits Apoptosis of Human Cultured Mesangial Cells Induced by Oxidized LDL

Deposition of atherogenic lipoproteins is associated with various glomerular diseases. In particular, oxidized LDL (oxLDL) may affect mesangial cells and favour the development of glomerulosclerosis. The aim of the present study was to investigate on cultured human mesangial cells (HMC) whether oxLDL induces apoptosis by a mechanism dependent on the inhibition of Akt survival pathway, and whether the engagement of mesangial CD40 by its ligand CD154 inhibits the apoptotic effect of oxLDL. Tunel assays demonstrated that incubation of HMC for 24h with oxLDL, but not with unmodified LDL, induced a dose-dependent increase in apoptosis of HMC associated with a decrease in Akt phosphorylation. Enzymatic kinase assay showed that also the Akt activity was reduced in a dose-dependent manner by treatment with oxLDL. Stimulation of mesangial CD40 with sCD154 rescued HMC from oxLDL-dependent apoptosis, while two unrelated pharmacological inhibitors of PI3K LY294002 and wortmannin abrogated this anti-apoptotic effect, suggesting an involvement of the PI3K/Akt pathway. Moreover CD40 stimulation maintained an elevated phosphorylation of Akt and preserved its enzymatic activity in the presence of oxLDL. Indeed, CD154 induced a rapid enhancement in Akt enzymatic activity, that was temporarily correlated with the association of CD40 with TRAF3, TRAF6, c-Cbl and the p85 subunit of PI3K. In conclusion, these results suggest that CD40 stimulation protects HMC from toxic effects of oxLDL by promoting PI3K/Akt-dependent cell survival.

Protein Kinase Cζ Regulation of Hypertrophic and Apoptotic Events Occurring during Rat Neonatal Heart Development and Growth

The development and growth of the rat heart implies hyperplasia, which stops at birth, and hypertrophy, allowing cardiac mass to grow in response to programmed genetic events along with to haemodynamic overload. Moreover, hypertrophy is accomplished to apoptosis which controls the final number of myocardial cells, deletes vestigial structures, and takes part in remodelling the organ. Since at the basis of all these processes, which lead to the complete development of the heart, the activation of specific signalling pathways underlies, attention has been addressed to the role played in vivo by Protein Kinase Cζ (PKCζ) in regulating NF-kB signalling system and “intrinsic” mitochondrial apoptotic route at days 1, 4, 10 and 22 of rat life. In fact, a role has been assigned to PKCζ in indirectly phosphorylating IKBα, which peaks between 10 and 22 days, through a IKK determining, in turn, NF-kB activation, concomitantly to cytochrome c/Apaf 1 co-localization in the cytoplasm and caspase-9/caspase-3 activation, which leads to the occurrence of apoptosis. Thus a key role for PKCζ in regulating the hypertrophic and apoptotic events leading to establishment of complete function in rat neonatal heart is here suggested.

Serum Evaluation of Angiogenic Cytokines Basic Fibroblast Growth Factor, Hepatocyte Growth Factor and TNF-ALPHA in Patients with Myelodysplastic Syndromes: Correlation with Bone Marrow Microvascular Density

Recent studies have documented that angiogenesis plays a significant role in haematological malignancies, including mylodysplastic syndromes (MDS). Basic fibroblast growth factor (b-FGF), Hepatocyte growth factor (HGF) and Tumor necrosis factor-α (TNF-α) are multifunctional cytokines that potently stimulate angiogenesis. The aim of the present study was to evaluate the microvascular density (MVD) and the serum levels of these angiogenic factors in patients with myelodysplastic syndromes (MDS). In 61 patients with MDS, MVD was measured in bone marrow biopsies and b-FGF, HGF and TNF-α were determined in the serum of the same patients by enzyme-linked immunosorbent assay (ELISA). Serum levels of b-FGF, HGF and TNF-α as well as MVD in the bone marrow were increased in MDS patients compared to healthy controls (p<0.0001). Levels of b-FGF, HGF and TNF-α were also significantly higher in high-risk for leukemic transformation MDS than in low-risk (p<0.0001). Significant differences were also found regarding MVD in high and low risk patients (p<0.001). Both b-FGF and HGF levels were significant predictors of survival (p<0.0005, log-rank test). The present study showed that serum levels of b-FGF, HGF and TNF-α are significantly increased and dependent on the severity of MDS suggesting that the determination of these parameters may offer considerable information regarding disease progression and prognosis.

Omeprazole Induces Apoptosis in Jurkat Cells

We report for the first time a potent apoptotic effect of omeprazole (OM). Apoptosis was induced in Jurkat cells in a time and concentration-dependent mode. Caspase 3 and PARP were rapidly cleaved in response to OM, but apoptosis was only partially inhibited by the caspase 3 inhibitor DEVD-CHO. OM also induced an early lysosomal destabilization which increased progressively and was correlated with a parallel increase in apoptotic cells. The cysteine protease inhibitor E64d gave strong protection against apoptosis thus proving the involvement of lysosomal enzymes in OM-induced apoptosis whereas, it did not impede the caspase 3 cleavage. Instead ZVAD-fmk, a general caspase inhibitor, also able to inhibit cathepsin activity, protected cells completely from OM-induced apoptosis. It therefore seems that both caspases and cysteine cathepsins are involved in the execution stage of OM-induced apoptosis.

A Limited Autoimmunity to p185neu Elicited by DNA and Allogeneic Cell Vaccine Hampers the Progression of Preneoplastic Lesions in HER-2/NEU Transgenic Mice

Prevention of the progression of precancerous lesions by vaccines is a virtually uncharted territory. Their potential, however, is being assessed in transgenic mice which develop autochthonous tumors with defined stages of progression. In this paper we show that the DNA micro-array technology significantly helps assessment of the preventive efficacy of a combined DNA and cell vaccine. All female rat Her-2/neu transgenic BALB/c (BALB-neuT) mice develop an invasive carcinoma in each of their mammary glands within 25 weeks of age. This is elicited by the activated transforming rat Her-2/neu oncogene embedded in their genome. We have previously shown that vaccination of mice bearing multiple in situ carcinomas with DNA plasmids which code for the extracellular and transmembrane domain of rat p185neu, the product of the rat Her-2/neu oncogene, followed by a boost with rat p185neu+ allogeneic cells engineered to secrete interferon-γ, keeps 48% of mice tumor free until week 32. We have now extended our follow-up until mice reach one year of age and show that protection vanishes as time progresses. This observation suggests that the accuracy of the results studying immunotherapy against life-threatening tumors is a function of the length of the follow-up. The application of microarrays, and the concordance of morphologic and gene expression data led us to identify antibody as the main mechanism induced by vaccination. Protection is associated with a break of tolerance and a limited autoimmunity against the

Expression of the High-Affinity Laminin Receptor (67 kDa) in Normal Human Skin and Appendages

The interaction of cells with extracellular matrix components plays a significant role in the regulation of cell biology. Laminin is a large glycoprotein involved in fundamental interactions between cells and the basement membrane. Several cell surface receptors are responsible for cell-matrix interactions. The 67 kDa high affinity laminin receptor, 67LR, is involved in the adhesion of normal cells to the laminin network and is also associated with the metastatic phenotype of some tumoral cells. We have investigated the expression of laminin and of the 67LR in normal human skin using immunoperoxidase staining. Twenty samples of skin were analyzed. Antibody against laminin reacted in a continuous linear band at the dermal-epidermal junction, as well as basement membranes of hair follicles, sebaceous and eccrine sweat glands, and dermal blood vessels. The epidermis and the follicular epithelium were negative for laminin. The 67LR seemed not to be expressed on the basal surface of basal keratinocytes. The major expression of this receptor may be detected in the upper half of the spinous layer and in the granular layer. The cells of the outer root sheath in hair follicle showed the same immunohistochemical pattern described for epidermis. In sebaceous glands and in eccrine sweat glands the secreting epithelium was positive. Endothelial cells of dermal blood vessels were routinely positive for 67LR. We observed that the expression of the 67LR in normal human skin is mostly located in epidermal areas in which the keratinizing process was particularly advanced.

High-dose etoposide in allogeneic stem cell transplantation

The anti-leukemic effect of etoposide is well documented. High-dose etoposide 60 mg/kg in combination with fractionated total body irradiation (TBI), usually single fractions of 1.2 Gy up to a total of 13.2 Gy, is used as conditioning therapy for allogeneic stem cell transplantation. Most studies of this conditioning regimen have included patients with acute leukemia receiving bone marrow or mobilized stem cell grafts derived from family or matched unrelated donors, and the treatment is then effective even in patients with high-risk disease. The most common adverse effects are fever with hypotension and rash, nausea and vomiting, sialoadenitis, neuropathy and metabolic acidosis. A small minority of patients develop severe allergic reactions. Etoposide has also been tested in a wide range of combination regimens, but for many of these combinations, relatively few patients are included, and some combinations have only been tested in patients who have undergone autologous transplants. However, the general conclusion is that many of these combinations are effective in patients with high-risk malignancies and the toxicity often seems acceptable. Thus, etoposide-based conditioning therapy should be further evaluated in patients having allogeneic transplants, but randomized trials are needed and the design of future trials should be based on the well-characterized TBI + high-dose etoposide regimen.

The regulatory mechanism of β-eudesmol is through the suppression of caspase-1 activation in mast cell-mediated inflammatory response

β-Eudesmol is sesquiterpenoid alcohol which contains the rhizome of Atractylodes lancea. Although it has multiple pharmacological effects, the anti-inflammatory effect of β-eudesmol and its molecular mechanisms are poorly elucidated. In this study, we investigated the regulatory mechanism of β-eudesmol on mast cell-mediated inflammatory response. The results indicated that β-eudesmol inhibited the production and expression of interleukin (IL)-6 on phorbol 12-myristate 13-acetate and calcium ionophore A23187-stimulated human mast cell (HMC). In activated HMC-1 cells, β-eudesmol suppressed activation of p38 mitogen-activated protein kinase (MAPKs) and nuclear factor-κB. In addition, β-eudesmol suppressed the activation of caspase-1 and expression of receptor-interacting protein-2. These results provide new insights into the pharmacological actions of β-eudesmol as a potential molecule for use in therapy in mast cell-mediated inflammatory diseases.

Ionizing radiation induces apoptotic signal through protein kinase Cdelta (delta) and survival signal through Akt and cyclic-nucleotide response element-binding protein (CREB) in Jurkat T cells

Although ionizing radiation induces a loss of proliferative capacity as well as cell death by apoptosis and necrosis, cells can oppose the damaging effects by activating survival signal pathways. Here we report the effect of 1.5- and 6-Gy doses of ionizing radiation on apoptotic protein kinase Cdelta (PKCdelta) and survival cyclic-nucleotide response element-binding protein (CREB) signal in Jurkat T cells. Cell cycle analysis, performed by flow cytometry, showed a significant G2M arrest 24 h after exposure to 6 Gy. This arrest was accompanied by dead cells, which increased in number up to 7 days, when cell viability was further reduced. The response was apparently promoted by caspase-3-mediated PKCdelta activation, and thus apoptosis. Moreover, the presence of viable cells up to 7 days in samples exposed to 6 Gy is explained by Akt activation, which may influence the nuclear transcription factor CREB, leading to resistance to ionizing radiation. Thus, the knowledge of apoptotic and survival pathways activated in tumor cells may help in establishing specific therapies by combining selective inhibitors or stimulators of key signaling proteins with conventional chemotherapy, hormone therapy, and radiotherapy.

Omeprazole Induces Apoptosis in Normal Human Polymorphonuclear Leucocytes

We investigated in vitro apoptosis in human polymorphonuclear neutrophils (PMN) induced by omeprazole. This drug, both in the native (OM) and acidified (OM-HCl) form, is a potent inducer of PMN apoptosis. The effect is time- and dose-dependent. OM-HCl is more efficient than OM in inducing PMN apoptosis. In fact, after 24 h incubation in vitro at 1×10 −4M OM-HCl induces apoptosis in 70% of the cell population compared to 37% induced by OM. Apoptosis induced by both forms of the drug is caspase dependent being significantly reduced by pretreating cells with the caspase 3 inhibitor (DEVDH-CHO). However, some differences in the apoptosis mechanisms between the two forms of the drug seem to exist because PMN treatment with the specific caspase 8 inhibitor (Z-IETD-FMK) only blocks OM-HCl mediated apoptosis. We observed cleavage of caspase 8 only in the cells incubated with OM-HCl while the executioner caspase 3 was activated with both forms of the drug. Furthermore, pretreatment with GM-CSF, a known activator of intracellular survival pathways in PMN, partially protected cells from OM-HCl induced apoptosis but did not contrast the apoptotic effect of OM. Cysteine cathepsin proteases also seem involved in the apoptotic mechanism of both drug forms since the specific inhibitor E64d gave a significant protection. To verify if OM-HCl induced apoptosis was dependent on the sulfenamide bound with the cell sulfhydryl groups we used molecules with thiol groups such as β-mercaptoethanol (β-ME) and reduced glutathione (GSH). Reactions of OM-HCl with cellular sulfhydryl groups are strongly involved in both the triggering and evolving phase of the apoptotic mechanism since significant protection from apoptosis was obtained when PMN were pretreated for 1h with β-ME (lipid-permeable) or GSH (lipid-impermeable). These results show that OM and OM-HCl induce apoptosis in human PMN and suggest that the second binds the sulfhydryl groups, present on the cell membrane, to then penetrate the cell thus causing a further significant increase in apoptosis. OM-induced PMN apoptosis during the treatment of gastric inflammatory disease could be an advantage for the resolution of the phlogosis state. However, this aspect should be further elucidated to assess the optimal therapeutical regimen for gastric diseases which are related to infective agents.

Nuclear protein kinase C-delta: a possible check-point of cell cycle progression

Protein kinase Cs (PKCs) belong to a serine/threonine kinase family, ubiquitously expressed and claimed to be involved in physiological processes including apoptosis, cell growth and differentiation. The question of the subcellular localization and activity of PKCs remains to be clarified. Here we report that nuclear PKC-delta cooperates to regulate the S-G2/M phase transition of cell cycle, apparently being associated to chromosome condensation and alignment on the metaphase plate.

JNK/p53 mediated cell death response in K562 exposed to etoposide-ionizing radiation combined treatment

The study of the ability of chemotherapeutic agents and/or ionizing radiation (IR) to induce cell death in tumor cells is essential for setting up new and more efficient therapies against human cancer. Since drug and ionizing radiation resistance is an impediment to successful chemotherapy against cancer, we wanted to check if etoposide/ionizing radiation combined treatment could have a synergic effect to improve cell death in K562, a well-known human erythroleukemia ionizing radiation resistant cell line. In this study, we examined the role played by JNK/SAPK, p53, and mitochondrial pathways in cell death response of K562 cells to etoposide and IR treatment. Our results let us suppose that the induction of cell death, already evident in 15 Gy exposed cells, mainly in 15 Gy plus etoposide, may be mediated by JNK/SAPK pathway. Moreover, p53 is a potential substrate for JNK and may act as a JNK target for etoposide and ionizing radiation. Thus further investigation on these and other molecular mechanisms underlying the cell death response following etoposide and ionizing radiation exposure could be useful to overcome resistance mechanisms in tumor cells.