The Bcl-2 protein family and its role in the development of neoplastic disease

The Role of JAK/STAT Signaling Pathway and Its Downstream Influencing Factors in the Treatment of Atherosclerosis

Atherosclerosis is now widely considered to be a chronic inflammatory disease, with increasing evidence suggesting that lipid alone is not the main factor contributing to its development. Rather, atherosclerotic plaques contain a significant amount of inflammatory cells, characterized by the accumulation of monocytes and lymphocytes on the vessel wall. This suggests that inflammation may play a crucial role in the occurrence and progression of atherosclerosis. As research deepens, other pathological factors have also been found to influence the development of the disease. The Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway is a recently discovered target of inflammation that has gained attention in recent years. Numerous studies have provided evidence for the causal role of this pathway in atherosclerosis, and its downstream signaling factors play a significant role in this process. This brief review aims to explore the crucial role of the JAK/STAT pathway and its representative downstream signaling factors in the development of atherosclerosis. It provides a new theoretical basis for clinically affecting the development of atherosclerosis by interfering with the JAK/STAT signaling pathway.

Crosstalk of the Wnt/β-Catenin Signaling Pathway in the Induction of Apoptosis on Cancer Cells

The Wnt/β-catenin signaling pathway plays a major role in cell survival and proliferation, as well as in angiogenesis, migration, invasion, metastasis, and stem cell renewal in various cancer types. However, the modulation (either up- or downregulation) of this pathway can inhibit cell proliferation and apoptosis both through β-catenin-dependent and independent mechanisms, and by crosstalk with other signaling pathways in a wide range of malignant tumors. Existing studies have reported conflicting results, indicating that the Wnt signaling can have both oncogenic and tumor-suppressing roles, depending on the cellular context. This review summarizes the available information on the role of the Wnt/β-catenin pathway and its crosstalk with other signaling pathways in apoptosis induction in cancer cells and presents a modified dual-signal model for the function of β-catenin. Understanding the proapoptotic mechanisms induced by the Wnt/β-catenin pathway could open new therapeutic opportunities.

Phenethyl isothiocyanate synergistically induces apoptosis with Gefitinib in non-small cell lung cancer cells via endoplasmic reticulum stress-mediated degradation of Mcl-1

Isothiocyanates (ITCs) are natural compounds abundant in cruciferous vegetables. Numerous studies have shown that ITCs exhibit anticancer activity by affecting multiple pathways including apoptosis and oxidative stress, and are expected to be developed into novel anticancer drugs. In our previous studies, we demonstrated that ITCs effectively inhibit the proliferation of non-small cell lung cancer (NSCLC) cells, also induce apoptosis and autophagy. In the present study, we found that phenethyl isothiocyanate (PEITC) had significant synergistic effects with epidermal growth factor receptor tyrosine kinase inhibitor Gefitinib in NSCLC cell lines NCI-H1299 and SK-MES-1; and the degradation of antiapoptotic factor myeloid cell leukemia 1 (Mcl-1) caused by PEITC treatment played key roles in the sensitivity of NSCLC cells to Gefitinib. We further illustrated that PEITC regulated the expression of Mcl-1 through protein kinase RNA-like endoplasmic reticulum kinase (PERK)-eukaryotic translation initiation factor 2α-CHOP-Noxa pathway by a posttranscriptional modulation. Pretreatment with endoplasmic reticulum stress (ER stress) inhibitor tauroursodeoxycholic acid and knockdown of PERK expression attenuated the degradation of Mcl-1 caused by PEITC. In in vivo study, nude mice bearing NCI-H1299 xenograft were administrated with PEITC (50 mg/kg, ip) and Gefitinib (50 mg/kg, ig) for 15 days, the PEITC-Gefitinib combination treatment resulted in a significant synergistic reduction in tumor growth, and significantly induced both ER stress and Mcl-1 degradation in tumor tissues. In conclusion, we explored the prospect of PEITC in improving the efficacy of targeted drug therapy and demonstrated the synergistic effects and underlined mechanisms of PEITC combined with Gefitinib in NSCLC cells treatment. This study provided useful information for developing novel therapy strategies by combination treatment of PEITC with targeted drugs.

Taiwanin C elicits apoptosis in arecoline and 4-nitroquinoline-1-oxide-induced oral squamous cell carcinoma cells and hinders proliferation via epidermal growth factor receptor/PI3K suppression

Oral Squamous Cell Carcinoma (OSSC) is a major life-threatening disease with high incidence in the Southeast Asian countries. Chronic exposure to arecoline causes genetic changes in the epithelial cells of the oral mucosa, induces proliferation through activation of the EGF receptor and promotes downstream COX-2 expression. Taiwanin C, a podophyllotoxin derived from Taiwania cryptomerioides Hayata is known to inhibit COX activity and to hinder PGE2 production in macrophages. In this study a tumor cell line T28 and a non-tumor cell line N28 derived from mice OSCC models were used to study the effect of Taiwanin C on PGE₂ associated COX-2 expression and cell cycle regulators. Taiwanin C activated p21 protein expression, down-regulated cell cycle regulatory proteins, elevated apoptosis and down-regulated p-PI3K/p-Akt survival mechanism in T28 oral cancer cells. Our results therefore emphasize the therapeutic potential of Taiwanin C against arecoline-induced oral cancer.

Conditioned media from adipocytes promote proliferation, migration, and invasion in melanoma and colorectal cancer cells

Epidemiological evidence suggests that obesity can significantly increase the risk of various cancers, although the mechanisms underlying this link are completely unknown. Here, we analyzed the effect of adipocytes on melanoma and colon cancer cells proliferation, migration, and invasion. The potential effects of conditioned media (CM) obtained from differentiated mouse 3T3-L1 cells and human adipose tissue-derived mesenchymal stem cells (hAMSC) on the proliferation, migration, and invasion of B16BL6 melanoma and colon 26-L5 cancer cells were investigated. The 3T3-L1 and hAMSC CM increased cell proliferation, migration, and invasion in both the cell lines. In addition, adipocytes CM increased matrix metalloproteinase 9 (MMP-9) and MMP-2 activity in both B16BL6 and colon 26-L5 cells. These effects were found to be associated with an increased expression of various oncogenic proteins in B16BL6 and colon 26-L5 cells. Also, adipocyte CM induced Akt and mTOR activation in both tumor cell lines, and the pharmacological inhibition of Akt and mTOR blocked the CM induced Akt as well as mTOR activation and CM-stimulated melanoma and colon cancer cell proliferation, migration, and invasion. These data suggest that adipocyte promotes melanoma and colon cancer progression through modulating the expression of diverse proteins associated with cancer growth and metastasis as well as modulation of the Akt/mTOR signaling.

Asiatic acid abridges pre-neoplastic lesions, inflammation, cell proliferation and induces apoptosis in a rat model of colon carcinogenesis

The utmost aim of this present study was to investigate the anti-inflammatory, antiproliferative and proapoptotic potential of Asiatic acid (AA) on 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in experimental rats. Rats were divided into six groups and received modified pellet diet for 32 weeks. Group 1 served as control rats. Group 2 received AA (4 mg/kg b.w. p.o.). Group 3-6 rats received 15 DMH (20 mg/kg b.w., s.c.) injections once a week starting from the 4th week. Besides DMH, rats received AA (4 mg/kg b.w. p.o.) in group 4 starting 2 weeks before carcinogen treatment till the end of the last DMH; group 5 starting 2 days after last DMH till the end of the experiment; and group 6 throughout the experiment. Pre-neoplastic lesions, xenobiotic metabolizing enzymes, inflammation, cell proliferation and apoptotic markers were analysed in our study. Our results ascertained AA supplementation to DMH-exposed rats significantly decreased the incidence of aberrant crypt foci (ACF) and phase I xenobiotic enzymes; and increased the phase II xenobiotic enzymes and mucin content as compared to DMH-alone-exposed rats. Moreover the increased expressions of mast cells, argyrophilic nucleolar organizer regions (AgNORs), proliferating cell nuclear antigen (PCNA) and cyclin D1 observed in the DMH-alone-exposed rats were reverted and were comparable with those of the control rats, when treated with AA. Concordantly AA also induced apoptosis by downregulating the expression of Bcl-2 and upregulating Bax, cytochrome c, caspase-3 and -9 in the DMH-alone-exposed rats. Thus AA was able to inhibit DMH-induced colon carcinogenesis by detoxifying the carcinogen, decreasing the preneoplastic lesions by virtue of its anti-inflammatory, antiproliferative and proapoptotic effects. Therefore our findings suggest that AA could be used as an effective chemopreventive agent against DMH induced colon carcinogenesis.

Detection of phosphatidylserine in the plasma membrane of single apoptotic cells using electrochemiluminescence

Phosphatidylserine in the plasma membrane of single apoptotic cells was detected using luminol electrochemiluminescence.

Phenylethyl isothiocyanate reverses cisplatin resistance in biliary tract cancer cells via glutathionylation-dependent degradation of Mcl-1

Biliary tract cancer (BTC) is a highly malignant cancer. BTC exhibits a low response rate to cisplatin (CDDP) treatment, and therefore, an understanding of the mechanism of CDDP resistance is urgently needed. Here, we show that BTC cells develop CDDP resistance due, in part, to upregulation of myeloid cell leukemia 1 (Mcl-1). Phenylethyl isothiocyanate (PEITC), a natural compound found in watercress, could enhance the efficacy of CDDP by degrading Mcl-1. PEITC-CDDP co-treatment also increased the rate of apoptosis of cancer stem-like side population (SP) cells and inhibited xenograft tumor growth without obvious toxic effects. In vitro, PEITC decreased reduced glutathione (GSH), which resulted in decreased GSH/oxidized glutathione (GSSG) ratio and increased glutathionylation of Mcl-1, leading to rapid proteasomal degradation of Mcl-1. Furthermore, we identified Cys16 and Cys286 as Mcl-1 glutathionylation sites, and mutating them resulted in PEITC-mediated degradation resistant Mcl-1 protein. In conclusion, we demonstrate for the first time that CDDP resistance is partially associated with Mcl-1 in BTC cells and we identify a novel mechanism that PEITC can enhance CDDP-induced apoptosis via glutathionylation-dependent degradation of Mcl-1. Hence, our results provide support that dietary intake of watercress may help reverse CDDP resistance in BTC patients.

The effects of buthionine sulfoximine on the proliferation and apoptosis of biliary tract cancer cells induced by cisplatin and gemcitabine

Patients with biliary tract cancer (BTC) have a poor prognosis. Advanced BTC patients have been treated with cisplatin in combination with gemcitabine, however, the treatment has had little impact on survival rates, and more effective treatments are urgently required for this disease. Previous studies discovered that buthionine sulfoximine (BSO), a potent inhibitor of glutathione (GSH) synthesis, was able to enhance the cytotoxic effect of various drugs in cancer cells. Phase I studies demonstrated that continuous-infusion of BSO was relatively non-toxic and resulted in the depletion of tumor GSH. However, the synergistic effect of BSO and cisplatin in BTC cells remains unknown, and no reports are available regarding sensitization to gemcitabine by BSO. In the present study, the effect of BSO in combination with cisplatin or gemcitabine in the treatment of BTC cells was examined in vitro. Cytotoxic effects were measured using an MTT assay, Annexin V assay and fluorescence-activated cell sorting analysis. Antiapoptotic protein expression levels were examined using western blot analysis. The results revealed that a sub-toxic concentration of BSO was capable of significantly enhancing cisplatin-induced apoptosis in BTC cells. The mechanisms of BSO's effect on BTC cells may be attributable to the reduction of GSH levels and downregulation of the expression of antiapoptotic proteins (Bcl-2, Bcl-xL and Mcl-1). Furthermore, BSO enhanced the antiproliferative effect of gemcitabine. In conclusion, the present data are the first results to indicate that BSO may sensitize BTC cells to standard first-line chemotherapeutic agents (cisplatin and gemcitabine). Combining BSO with cisplatin and gemcitabine is a promising therapeutic strategy for the treatment of BTC.

The synergistic antitumor effects of all-trans retinoic acid and C-phycocyanin on the lung cancer A549 cells in vitro and in vivo

The anticancer effects and mechanism of all-trans retinoic acid (ATRA), C-phycocyanin (C-PC) or ATRA+C-PC on the growth of A549 cells were studied in in vitro and in vivo experiments. The effects of C-PC and ATRA on the growth of A549 cells were determined. The expression of CDK-4 and caspase-3, and the cellular apoptosis levels were detected. The tumor model was established by subcutaneous injection of A549 cells to the left axilla of the NU/NU mice. The weights of tumor and the spleen were tested. The viabilities of T-cells and spleen cells, TNF levels, the expression of Bcl-2 protein and Cyclin D1 gene were examined. Results showed both C-PC and ATRA could inhibit the growth of tumor cells in vivo and in vitro. ATRA+C-PC cooperatively showed a higher antitumor activity. The dosage of ATRA was reduced when it was administered with C-PC together, and the toxicity was reduced as well. ATRA+C-PC could decrease CDK-4 but increase caspase-3 protein expression level and induce cell apoptosis. ATRA alone could lower the activities of T lymphocytes and spleen weights, but the combination with C-PC could effectively promote viability of T cells and spleen. C-PC+ATRA could up-regulate TNF, and down-regulate Bcl-2 and Cyclin D1 gene. The combination might inhibit tumor growth by inhibiting the progress of cell cycle, inducing cell apoptosis and enhancing the body immunity.

Induction of apoptosis in HCT-116 colon cancer cells by polysaccharide of Larimichthys crocea swim bladder

Larimichthys crocea swim bladder is a traditional food and medicine widely used in China. The in vitro anticancer effects of polysaccharide of L. crocea swim bladder (PLCSB) in HCT-116 human colon cancer cells was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. At concentrations ranging between 0 and 800 μg/ml PLCSB, cancer cell viability was decreased by PLCSB in a concentration-dependent manner. In particular, 400 μg/ml PLCSB significantly (P<0.05) induced apoptosis, which was demonstrated by 4,6-diamidino-2-phenylindole staining and flow cytometry analysis. To elucidate the mechanisms underlying the anticancer effect of PLCSB in HCT-116 cancer cells, the expression of apoptosis and metastasis-associated genes was analyzed by reverse transcription-polymerase chain reaction and western blot analysis. A total of 400 μg/ml PLCSB significantly induced apoptosis in HCT-116 cells (P<0.05) via the upregulation Bax, p53, p21, apoptotic protease activating factor 1, caspase-3, -8, and -9, as well as Fas and the downregulation of B-cell lymphoma 2 (Bcl-2), Bcl-extra large and Fas ligand (L). The results of this study demonstrated that PLCSB exhibits an anticancer effect on HCT-116 colon cancer cells, in vitro.

Heat shock response associated with hepatocarcinogenesis in a murine model of hereditary tyrosinemia type I

Hereditary Tyrosinemia type 1 (HT1) is a metabolic liver disease caused by genetic defects of fumarylacetoacetate hydrolase (FAH), an enzyme necessary to complete the breakdown of tyrosine. The severe hepatic dysfunction caused by the lack of this enzyme is prevented by the therapeutic use of NTBC (2-[2-nitro-4-(trifluoromethyl)benzoyl] cyclohexane-1,3-dione). However despite the treatment, chronic hepatopathy and development of hepatocellular carcinoma (HCC) are still observed in some HT1 patients. Growing evidence show the important role of heat shock proteins (HSPs) in many cellular processes and their involvement in pathological diseases including cancer. Their survival-promoting effect by modulation of the apoptotic machinery is often correlated with poor prognosis and resistance to therapy in a number of cancers. Here, we sought to gain insight into the pathophysiological mechanisms associated with liver dysfunction and tumor development in a murine model of HT1. Differential gene expression patterns in livers of mice under HT1 stress, induced by drug retrieval, have shown deregulation of stress and cell death resistance genes. Among them, genes coding for HSPB and HSPA members, and for anti-apoptotic BCL-2 related mitochondrial proteins were associated with the hepatocarcinogenetic process. Our data highlight the variation of stress pathways related to HT1 hepatocarcinogenesis suggesting the role of HSPs in rendering tyrosinemia-affected liver susceptible to the development of HCC.

Expression of COX-2 and bcl-2 in oral lichen planus lesions and lichenoid reactions

Oral lichen planus and lichenoid reactions are autoimmune type inflammatory conditions of the oral mucosa with similar clinical and histological characteristics. Recent data suggest that oral lichenoid reactions (OLR) present a greater percentage of malignant transformation than oral lichen planus (OLP).

Targeting mitochondria as therapeutic strategy for metabolic disorders

Mitochondria are critical regulator of cell metabolism; thus, mitochondrial dysfunction is associated with many metabolic disorders. Defects in oxidative phosphorylation, ROS production, or mtDNA mutations are the main causes of mitochondrial dysfunction in many pathological conditions such as IR/diabetes, metabolic syndrome, cardiovascular diseases, and cancer. Thus, targeting mitochondria has been proposed as therapeutic approach for these conditions, leading to the development of small molecules to be tested in the clinical scenario. Here we discuss therapeutic interventions to treat mitochondrial dysfunction associated with two major metabolic disorders, metabolic syndrome, and cancer. Finally, novel mechanisms of regulation of mitochondrial function are discussed, which open new scenarios for mitochondria targeting.

Molecular mechanism of inhibitory effects of C-phycocyanin combined with all-trans-retinoic acid on the growth of HeLa cells in vitro

We studied the effects of all-trans-retinoic acid (ATRA), C-phycocyanin (C-PC), or ATRA+C-PC on the growth of cervical cells (HeLa cells), cell cycle distribution, and apoptosis. The anticancer mechanism of the drug combination was revealed. MTT assay was adopted to determine the effects of C-PC and ATRA on the growth of HeLa cells. The expression quantities of cyclin-dependent kinase (CDK) 4, cyclin D1, Bcl-2, caspase-3, and CD59 were determined by in situ hybridization, immunofluorescence, immunohistochemistry staining, Western blot, and RT-PCR. TUNEL assay was adopted to determine the cellular apoptosis levels. Both C-PC and ATRA could inhibit the growth of HeLa cells, and the combination of ATRA+C-PC functioned cooperatively to induce apoptosis in HeLa cells. The dosage of ATRA was reduced when it cooperated with C-PC to reduce the toxicity. ATRA treated with C-PC could induce more cell cycle arrests than the single drug used by decrease in cyclin D1 and CDK4 expression. The combination of the two drugs could upregulate caspase-3 and downregulate the Bcl-2 gene and induce cell apoptosis. Moreover, the combination therapy has an important immunological significance in decreased expression of the CD59 protein. Singly, C-PC or ATRA could inhibit the growth of HeLa cells, and the effects of treatment were further enhanced in the combination group. In combination with C-PC, the dosage of ATRA was effectively reduced. The C-PC + ATRA combination might take effect by inhibiting the progress of the cell cycle, inducing cell apoptosis and promoting complement-mediated cytolysis.

Molecular mechanisms underlying antiproliferative and differentiating responses of hepatocarcinoma cells to subthermal electric stimulation

Capacitive Resistive Electric Transfer (CRET) therapy applies currents of 0.4–0.6 MHz to treatment of inflammatory and musculoskeletal injuries. Previous studies have shown that intermittent exposure to CRET currents at subthermal doses exert cytotoxic or antiproliferative effects in human neuroblastoma or hepatocarcinoma cells, respectively. It has been proposed that such effects would be mediated by cell cycle arrest and by changes in the expression of cyclins and cyclin-dependent kinase inhibitors. The present work focuses on the study of the molecular mechanisms involved in CRET-induced cytostasis and investigates the possibility that the cellular response to the treatment extends to other phenomena, including induction of apoptosis and/or of changes in the differentiation stage of hepatocarcinoma cells. The obtained results show that the reported antiproliferative action of intermittent stimulation (5 m On/4 h Off) with 0.57 MHz, sine wave signal at a current density of 50 µA/mm², could be mediated by significant increase of the apoptotic rate as well as significant changes in the expression of proteins p53 and Bcl-2. The results also revealed a significantly decreased expression of alpha-fetoprotein in the treated samples, which, together with an increased concentration of albumin released into the medium by the stimulated cells, can be interpreted as evidence of a transient cytodifferentiating response elicited by the current. The fact that this type of electrical stimulation is capable of promoting both, differentiation and cell cycle arrest in human cancer cells, is of potential interest for a possible extension of the applications of CRET therapy towards the field of oncology.

A phase I study of AT-101 with cisplatin and etoposide in patients with advanced solid tumors with an expanded cohort in extensive-stage small cell lung cancer

BACKGROUND

A phase I, dose-escalation study of AT-101 with cisplatin and etoposide was conducted to determine the maximum tolerated dose (MTD)/recommended phase 2 dose (RP2D), safety and pharmacokinetics in patients with advanced solid tumors, with an expanded cohort in patients with extensive-stage small cell lung cancer (ES-SCLC) to assess preliminary activity.

METHODS

In the dose escalation portion, increasing doses of AT-101 were administered orally BID on days 1-3 along with cisplatin on day 1 and etoposide on days 1-3 of a 21 day cycle. At the RP2D, an additional 7 patients with untreated ES-SCLC were enrolled.

RESULTS

Twenty patients were enrolled in the dose-escalation cohort, and 7 patients with ES-SCLC were enrolled in the expanded cohort. The MTD/RP2D was established at AT-101 40 mg BID days 1-3 with cisplatin 60 mg/m2 and etoposide 120 mg/m2 on day 1 of a 21 day cycle with pegfilgrastim support. Two DLTs of neutropenic fever were seen at dose level 1. After the addition of pegfilgrastim, no additional DLTs were observed. Grade 3/4 treatment-related toxicities included: diarrhea, increased AST, neutropenia, hypophosphatemia, hyponatremia, myocardial infarction and pulmonary embolism. No apparent PK interactions were observed between the agents. Preliminary activity was observed with PRs in patients with ES-SCLC, high-grade neuroendocrine tumor, esophageal cancer and NSCLC.

CONCLUSIONS

AT-101 with cisplatin and etoposide is well tolerated with growth factor support. Anti-tumor activity was observed in a variety of cancers including ES-SCLC, supporting further investigation with BH-3 mimetics in combination with standard chemotherapy for ES-SCLC.

NK4 regulates 5-fluorouracil sensitivity in cholangiocarcinoma cells by modulating the intrinsic apoptosis pathway

The aim of the present study was to investigate the role of NK4, an antagonist for hepatocyte growth factor (HGF) and the Met receptor, in regulating the response of cholangiocarcinoma (CCA) cells to 5-fluorouracil (5-FU). We established the CCA cell line, HuCC-T1, to produce abundant NK4 (Hu-NK4). Cell proliferation, cell cycle distribution, apoptosis, 5-FU metabolism and intracellular signaling were examined. There were no significant differences in the mRNA levels of thymidylate synthase, thymidine phosphorylase and dihydropyrimidine dehydrogenase between the mock-transfected control Hu-Em cells and Hu-NK4 cells, suggesting that NK4 expression does not alter 5-FU metabolism. Moreover, cell cycle analysis showed that 5-FU treatment caused a decrease in the proportion of cells in the G2/M phase while NK4 gene expression had little effect on the cell cycle distribution. However, 5-FU-induced apoptosis was significantly increased in the Hu-NK4 cells when compared to that in the Hu-Em cells. Further investigation revealed that NK4 gene expression enhanced 5-FU-induced caspase-3 and caspase-9 activation, and that the apoptosis of cells was associated with modulation of expression of the Bcl-2 family members. Furthermore, western blot analysis revealed that both NK4 and 5-FU were inhibitors for HGF-induced phosphorylation of Met, but they may be independent factors. Collectively, these results suggest that following 5-FU treatment in CCA cell lines, NK4 was involved in apoptosis induction through the intrinsic mitochondrial pathway. This indicates that NK4 may be an important mediator of 5-FU-induced cell death. Moreover, downregulation of NK4 in response to 5-FU may represent an intrinsic mechanism of resistance to this anticancer drug.

Leptin stimulates ovarian cancer cell growth and inhibits apoptosis by increasing cyclin D1 and Mcl-1 expression via the activation of the MEK/ERK1/2 and PI3K/Akt signaling pathways

Obesity is known to be an important risk factor for many types of cancer, such as breast, prostate, liver and endometrial cancer. Recently, epidemiological studies have indicated that obesity correlates with an increased risk of developing ovarian cancer, the most lethal gynecological cancer in developed countries. Leptin is predominantly produced by adipocytes and acts as a growth factor and serum leptin levels positively correlate with the amount of body fat. In this study, we investigated the effects of leptin on the growth of ovarian cancer cells and the underlying mechanism(s) of action. Our results showed that leptin stimulated the growth of the OVCAR-3 ovarian cancer cell line using MTT assay and trypan blue exclusion. Using western blot analysis, we found that leptin enhanced the expression of cyclin D1 and Mcl-1, which are important regulators of cell proliferation and the inhibition of apoptosis. To investigate the signaling pathways that mediate the effects of leptin, cells were treated with leptin plus specific inhibitors of JAK2, PI3K/Akt and MEK/ERK1/2 and analysis of the phosphorylation state of proteins was carried out by western blot assays. We showed that the activation of the MEK/ERK1/2 and PI3K/Akt signaling pathways were involved in the growth-stimulating effect of leptin on ovarian cancer cell growth and the specific inhibitors of PI3K/Akt and MEK/ERK1/2 revealed that these two pathways interacted with each other. Our data demonstrate that leptin upregulates the expression of cyclin D1 and Mcl-1 to stimulate cell growth by activating the PI3K/Akt and MEK/ERK1/2 pathways in ovarian cancer.

Altered expression of cellular Bcl-2 in the progression of hamster cholangiocarcinogenesis

Bcl-2 is an intracytoplasmic and membrane-associated apoptosis suppressor, and its overexpression is closely associated with survival of malignant tumors, in particular their aggressive behavior and poor prognosis. The role of Bcl-2 is, however, still controversial in cholangiocarcinogenesis because of the discrepancies in the expression of the protein. In the present study, alteration in the expression of Bcl-2 in cholangiocarcinogenesis was investigated by studying the immunoreactivities of this protein in normal, hyperplastic bile ducts with or without dysplastic changes, and neoplastic bile duct cells from a hamster cholangiocarcinoma (ChC) model. Cytoplasmic staining, which reflects high-Bcl-2 immunoreactivity, was negative to very weak in normal and hyperplastic bile ducts without dysplastic changes, while hyperplastic bile ducts with dysplasia indicated heterogeneously strong expression. On the other hand, most of the neoplastic cells of invasive cholangiocarcinomas were negative to weak as much as the level of normal bile ducts. The results suggest that the antiapoptotic factor Bcl-2 plays a limited role in the survival of highly proliferative, potentially dysplastic bile duct cells. However, the role of Bcl-2 in biliary cancer cells was not significant.

Downregulation of Mcl-1 synergizes the apoptotic response to combined treatment with cisplatin and a novel fiber chimeric oncolytic adenovirus

The aim of this study was to examine the effects of SG511, a novel fiber chimeric oncolytic adenovirus with E1B 55-kDa deleted, combined with cisplatin on cancer cells and to identify their underlying mechanisms. The combined effect of SG511 and cisplatin on HeLa and HT-29 cells was assessed by a crystal violet assay and an MTT assay, followed by combination index analysis. Cell apoptosis was evaluated by DAPI staining and visualized by fluorescein-mediated signal detection. Mitochondrial membrane potential was detected by flow cytometric analysis of Rhodamine 123 accumulation. The activation of the caspase pathway and the expression of Bcl-2 family proteins were examined by western blotting. Results show that SG511 vector infected various human cancer cell lines and induced growth inhibition effectively. Of note, SG511 synergistically enhanced the anti-proliferative activity of cisplatin, a DNA-damaging agent, against HeLa and HT-29 cells in vitro, concomitantly with increased apoptosis and activation of the mitochondrial pathway. Furthermore, treatment with SG511 alone or in combination with cisplatin resulted in reduced expression the anti-apoptotic Bcl-2 family member Mcl-1 in HeLa and HT-29 cells. Importantly, this combination did not increase the growth inhibitory effects of cisplatin on human normal liver cells. Collectively, SG511, a novel fiber chimeric oncolytic adenovirus, sensitizes cancer cells to apoptosis by reducing anti-apoptotic Mcl-1 protein levels.

Ellagic acid coordinately attenuates Wnt/β-catenin and NF-κB signaling pathways to induce intrinsic apoptosis in an animal model of oral oncogenesis

PURPOSE

Constitutive activation of the Wnt signaling pathway and its downstream effectors plays a key role in neoplastic transformation. The objective of this study was to investigate the effect of ellagic acid, a plant-derived polyphenol on Wnt/β-catenin signaling and its downstream circuits- NF-κB and mitochondrial apoptosis in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis model.

METHODS

Hamsters were divided into six groups. The right buccal pouches of animals in groups 1-4 were painted with 0.5% DMBA three times a week for 14 weeks. Animals in groups 2-4 received in addition basal diet containing ellagic acid at a concentration of 0.1, 0.2, and 0.4% in the diet. Group 5 animals were given 0.4% ellagic acid alone. Group 6 animals served as control. The expression of the members of Wnt and NF-κB signaling and intrinsic apoptosis was evaluated by western blot analysis.

RESULTS

Dietary supplementation of 0.4% ellagic acid suppressed the development of HBP carcinomas by preventing the constitutive activation of Wnt pathway through the downregulation of Fz, Dvl-2, GSK-3β and nuclear translocation of β-catenin. Abrogation of Wnt signaling by ellagic acid was also associated with inactivation of NF-κB and modulation of key components of the mitochondrial apoptotic network.

CONCLUSIONS

Our findings suggest a functional crosstalk between Wnt and NF-κB signaling pathways in HBP carcinomas that is blocked by ellagic acid supplementation. Dietary ellagic acid that targets the Wnt/β-catenin pathway as well as its downstream signaling mediators is a unique candidate for cancer chemoprevention.

Preferential killing of cancer cells with mitochondrial dysfunction by natural compounds

Mitochondria play essential roles in cellular metabolism, redox homeostasis, and regulation of cell death. Emerging evidences suggest that cancer cells exhibit various degrees of mitochondrial dysfunctions and metabolic alterations, which may serve as a basis to develop therapeutic strategies to preferentially kill the malignant cells. Mitochondria as a therapeutic target for cancer treatment is gaining much attention in the recent years, and agents that impact mitochondria with anticancer activity have been identified and tested in vitro and in vivo using various experimental systems. Anticancer agents that directly target mitochondria or indirectly affect mitochondrial functions are collectively classified as mitocans. This review article focuses on several natural compounds that preferentially kill cancer cells with mitochondrial dysfunction, and discusses the possible underlying mechanisms and their therapeutic implications in cancer treatment. Mitocans that have been comprehensively reviewed recently are not included in this article. Important issues such as therapeutic selectivity and the relevant biochemical basis are discussed in the context of future perspectives.

Effects of paeonol and 5-FU on the proliferation and apoptosis of human esophageal carcinoma EC9706 cells

AIM: To investigate the effects of paeonol alone or in combination with 5-fluorouracil (5-FU) on the proliferation and apoptosis of human esophageal carcinoma EC9706 cells.

METHODS: Six different concentrations of paeonol (7.81, 15.63, 31.25, 62.50, 125.00 and 250.00 mg/L, respectively), three different concentrations of 5-FU (12.50, 25.00 and 50.00 mg/L, respectively), and paeonol (31.25 mg/L) in combination with 5-FU (12.50 mg/L) were used to treat EC9706 cells for different durations (24, 48 and 72 h). Untreated EC9706 cells were used as the control group. The proliferation of EC9706 cells was detected by methyl thiazolyl tetrazolium (MTT) assay after treatment for different durations. After treatment of EC9706 cells with paeonol at concentrations of 31.25, 62.50, 125.00 and 250.00 mg/L for 72 hours, the cell cycle was analyzed by flow cytometry; cell morphological changes were observed using an inverted microscope; the morphology of apoptotic cells was observed by HE staining and light microscopy. The expression of apoptosis-associated proteins Bcl-2 and Bax was detected by immunocytochemistry after treatment of EC9706 cells with paeonol (31.25 mg/L) and 5-FU (12.50 mg/L), alone or in combination, for 48 hours.

RESULTS: Paeonol or 5-FU could significantly inhibit the proliferation of EC9706 cells in a concentration- and time-dependent manner (both P < 0.05). Paeonol in combination with 5-FU showed more significant inhibitory effects on the proliferation of EC9706 cells when compared with paeonol or 5-FU alone (both P < 0.05). Paeonol (125.00 mg/L) treatment altered the cell cycle distribution of EC9706 cells: the percentages of cells in G₀/G₁ and G₂/M phases decreased, while that of cells in S phase increased (G₀/G₁ phase: 21.18% ± 2.28% vs 62.17% ± 5.23%; G₂/M phase: 0.76% ± 0.54% vs 9.92% ± 3.10%; S phase 78.06% ± 2.82% vs 27.91% ± 2.13%; all P < 0.05). Typical apoptotic changes were observed in EC9706 cells treated with paeonol. Both paeonol and 5-FU down-regulated the expression of Bcl-2 and up-regulated the expression of Bax, which was especially prominent in the combination group (2.21 ± 0.14 vs 5.67 ± 0.30 and 4.22 ± 0.34; 8.55 ± 0.33 vs 3.90 ± 0.27 and 6.28 ± 0.26, all P < 0.05).

CONCLUSION: Paeonol can significantly inhibit the proliferation and induce the apoptosis of human esophageal carcinoma EC9706 cells. Paeonol in combination with 5-FU shows a synergistic effect in suppressing the proliferation and promoting the apoptosis of EC9706 cells.

Therapeutic modulation of apoptosis: targeting the BCL-2 family at the interface of the mitochondrial membrane

A vast portion of human disease results when the process of apoptosis is defective. Disorders resulting from inappropriate cell death range from autoimmune and neurodegenerative conditions to heart disease. Conversely, prevention of apoptosis is the hallmark of cancer and confounds the efficacy of cancer therapeutics. In the search for optimal targets that would enable the control of apoptosis, members of the BCL-2 family of anti- and pro-apoptotic factors have figured prominently. Development of BCL-2 antisense approaches, small molecules, and BH3 peptidomimetics has met with both success and failure. Success-because BCL-2 proteins play essential roles in apoptosis. Failure-because single targets for drug development have limited scope. By examining the activity of the BCL-2 proteins in relation to the mitochondrial landscape and drawing attention to the significant mitochondrial membrane alterations that ensue during apoptosis, we demonstrate the need for a broader based multi-disciplinary approach for the design of novel apoptosis-modulating compounds in the treatment of human disease.

Epigallocatechin-3-gallate induces apoptosis and cell cycle arrest in HTLV-1-positive and -negative leukemia cells

The objective of this study is to evaluate the efficacy of epigallocatechin gallate against ATL cells. The anti-proliferative and pro-apoptotic effects of EGCG were evaluated in HTLV-1-positive and -negative cells. EGCG exhibited a marked decrease in proliferation of ATL cells at 96 h of treatment. The results indicated that TGF-alpha was down-regulated whereas levels of TGF-beta2 increased. Cell cycle distribution analysis revealed an increase in cells in the pre-G(1) phase which was confirmed by ELISA. The results on proteins showed an up-regulation of p53, Bax and p21 protein levels while the levels of Bcl-2alpha were down-regulated.

Livin and Bcl-2 expression in high-grade osteosarcoma

AIMS

The evaluation of prognosis in patients with osteosarcoma is limited to clinical parameters. Although numerous molecular markers have been studied, none are currently in routine clinical use. The aim of this study was to determine if Livin and Bcl-2, acting as antiapoptotic proteins through different mechanisms, are expressed in osteosarcoma, and whether they can be used as prognostic markers in human osteosarcoma.

METHODS

Tumor specimens of 29 patients with high-grade central osteosarcoma, with complete clinical follow-up for a minimum of 5 years, were studied. The localization and distribution of Livin and Bcl-2 were investigated using immunohistochemistry. Results were correlated with the histological response to chemotherapy, 5-year disease-free and 5-year overall survival.

RESULTS

Bcl-2 was expressed only in the cytoplasm of 16/29 cases and there was no statistically significant correlation between expression and any of the studied parameters. Livin was detected in 17/29 cases, in the cytoplasm of all 17 and in the nucleus of only 3 cases. Nuclear expression was significantly correlated with a decreased overall survival (P < 0.0002) compared with those patients without nuclear expression.

CONCLUSIONS

The results of this study indicate that Bc1-2 and Livin are highly expressed in osteosarcoma cells and that possibly, the evaluation of nuclear Livin expression might be a useful prognostic marker in osteosarcoma.

Apoptotic cell death and its relationship to gastric carcinogenesis

AIM: To investigate the apoptotic process of cells within the intestinal metaplasia areas co-localizing with chronic gastritis and gastric carcinomas and to analyze the involvement of proteins regulating apoptosis in the process of intestinal metaplasia related gastric carcinogenesis.

METHODS: Forty-two gastric carcinoma and seventeen chronic gastritis cases were included in this study. All cases were examined for the existence of intestinal metaplasia. Ten cases randomly selected from each group were processed for TUNEL assay. TUNEL positive cells within the intestinal metaplasia areas, co-localizing either to gastric carcinoma or chronic gastritis, were counted and converted to apoptotic indices. In addition, p53, bcl-2 and bax expression patterns within these tissues were analyzed on the basis of immunohistochemistry.

RESULTS: Twenty-eight of the cases were intestinal and 14 of the cases were diffuse type adenocarcinomas. 64% (27/42) of the gastric carcinoma cases had intestinal metaplasia. Intestinal metaplasia co-localized more with intestinal type carcinomas compared with diffuse type carcinomas [75% (21/28) vs 42% (6/14), respectively; P≤ 0.05]. The mean apoptotic index in tumor cells was 0.70 ± 0.08. The mean apoptotic index in intestinal metaplasias co-localizing to tumors was significantly higher than that of intestinal metaplasias co-localizing to chronic gastritis (0.70 ± 0.03 vs 0.09 ± 0.01, respectively; P≤ 0.05). p53 positivity was not observed in areas of intestinal metaplasia adjacent to tumors or chronic gastritis. Intestinal metaplasia areas adjacent to tumors showed lower cytoplasmic bcl-2 positivity compared to intestinal metaplasia areas adjacent to chronic gastritis [55.5% (15/27) vs 70.5% (12/17), respectively]. On the other hand, intestinal metaplasia areas adjacent to tumors showed significantly higher cytoplasmic bax positivity compared to intestinal metaplasia areas adjacent to chronic gastritis [44.4% (12/27) vs 11.7% (2/17), respectively; P≤ 0.05].

CONCLUSION: Existence of apoptotic cells on the basis of TUNEL positivity is shown in intestinal metaplasias co-localizing to both diffuse and intestinal type gastric cancers in this study. Our results also suggested bax expression dependent induction of apoptosis especially in intestinal metaplasia areas adjacent to tumors. These findings strongly support the involvement of apoptotic mechanisms in the process of gastric carcinogenesis especially in the transition from intestinal metaplasia to gastric cancer. It may be suggested that induction of apoptosis in intestinal metaplasia areas adjacent to tumors may involve different mechanisms than induction by chronic inflammation.

Multifaceted targeting in cancer: the recent cell death players meet the usual oncogene suspects

Recent complicated advances towards the blueprinting of the altered molecular networks that lie behind cancer development have paved the way for targeted therapy in cancer. This directed a significant part of the research community to the development of specialized targeted agents, many of which are already available or in clinical trials. The prospect of patient-tailored therapeutic strategies, although very close to becoming a reality also raises the level of complexity of the therapeutic approach. This review summarizes the functions, in vivo expression patterns and aberrations of factors presently targeted or representing potential targets by therapeutic agents, focusing on those implicated in death receptor-induced apoptosis. The authors overview the regulation of these factors and death receptor-induced apoptosis by classical oncogenes (e.g., RAS, MYC, HER2) and their effectors/regulators, most of which are also being targeted. In addition, the importance of orthologic systemic approaches in future patient-tailored therapies are discussed.

Inhibition of the growth of human gastric carcinoma in vivo and in vitro by swainsonine

In Europe, swainsonine has been studied widely for prevention of metastasis and cancer therapy. In order to investigate the effects and mechanisms of swainsonine on the human gastric carcinoma SGC-7901 cell, we carried out in vivo and in vitro experiments. After treatment with swainsonine, an effective dose and IC50 value of swainsonine for SGC-7901 cells were examined by MTT assay. Cell-cycle distribution and apoptotic rates were analyzed using FCM, and [Ca2+]i was measured using LSCM. The expression of p53, c-myc and Bcl-2 were determined using an immunocytochemical method. Simultaneously, 50 mice were divided randomly into five groups. Three groups were administrated swainsonine at dose of 3, 6 and 12 mg/kg body wt., two control groups were administrated N.S. 20 ml/kg body wt. and 5-Fu 20 mg/kg body wt., respectively, by intraperitoneal injection. The inhibition rate was calculated and pathological sections were observed. The growth of SGC-7901 cell is inhibited by swainsonine in vitro, with an IC50 value at 24 h of 0.84 microg/ml, and complete inhibition concentration is 6.2 microg/ml. After treatment with swainsonine at the concentrations of 0.5, 1.5 and 4.5 microg/ml for 24 h, the expression of apoptosis inhibiting gene p53 and bcl-2 decreases, and the apoptotic trigger gene c-myc increases markedly (p<0.05), as well as [Ca2+]i overloading, SGC-7901 cell is induced to apoptosis in the end. It is also found that the percentages of S phase are 38.8%, 39.7% and 29.6%, respectively (20.0% in control group and 23.2% in 5-Fu group). The rates of inhibition were 13.2%, 28.9%, 27.3%, respectively, when the nude mice were administered swainsonine (p<0.05 or 0.01). The structure of the tumor showed hemorrhage, necrosis and inflammatory cell infiltration. We therefore conclude that swainsonine could inhibit cell proliferation in vitro and the growth of human gastric carcinoma in vivo. The mechanisms of swainsonine-induced apoptosis may relate to [Ca2+]i overloading and the expression of apoptosis-related genes.

[The role of matrix metalloproteinases and tissue inhibitors of metalloproteinases in invasion of tumours of neuroepithelial tissue]

Tumour invasion requires degradation of extracellular matrix components and migration of cells through degraded structures into surrounding tissues. Matrix metalloproteinases (MMP) constitute a family of zinc and calcium-dependent endopeptidases that play a key role in the breakdown of extracellular matrix, and in processing of cytokines, growth factors, chemokines and cell surface receptors. Their activity is regulated at the levels of transcription, activation and inhibition by tissue inhibitors of metalloproteinases (TIMP). Changes in expression of MMP and TIMP are implicated in tumour invasion, because they may contribute to both migration of tumour cells and angiogenesis. Alterations of MMP expression observed in brain tumours arouse interest in the development and evaluation of synthetic matrix metalloproteinase inhibitors as antitumour agents.

Bcl-2 protein family: implications in vascular apoptosis and atherosclerosis

Apoptosis has been recognized as a central component in the pathogenesis of atherosclerosis, in addition to the other human pathologies such as cancer and diabetes. The pathophysiology of atherosclerosis is complex, involving both apoptosis and proliferation at different phases of its progression. Oxidative modification of lipids and inflammation differentially regulate the apoptotic and proliferative responses of vascular cells during progression of the atherosclerotic lesion. Bcl-2 proteins act as the major regulators of extrinsic and intrinsic apoptosis signalling pathways and more recently it has become evident that they mediate the apoptotic response of vascular cells in response to oxidation and inflammation either in a provocative or an inhibitory mode of action. Here we address Bcl-2 proteins as major therapeutic targets for the treatment of atherosclerosis and underscore the need for the novel preventive and therapeutic interventions against atherosclerosis, which should be designed in the light of molecular mechanisms regulating apoptosis of vascular cells in atherosclerotic lesions.

MG132 induced apoptosis is associated with p53-independent induction of pro-apoptotic Noxa and transcriptional activity of beta-catenin

Noxa is a pro-apoptotic BH3-only member of the Bcl-2 family of proteins that is up-regulated at a transcriptional level by the nuclear protein p53 in response to cellular stresses such as DNA damage or growth factor deprivation. Noxa is able to interact with anti-apoptotic members of the Bcl-2 family and causes release of cytochrome c into the cytosol, leading to the activation of caspases and induction of apoptosis. Here we demonstrate that MG132, a proteasomal inhibitor, rapidly induces Noxa mRNA and protein in two human cell lines, T/C28a and Saos2. The induction of Noxa is associated with a significant reduction in the number of metabolically active cells over the first 24 h of exposure to MG132 and progressive activation of caspase-3, a hallmark of caspase-dependent apoptosis. Partial rescue of the phenotype is observed when cells are transfected with Noxa siRNA prior to treatment with MG132, indicating functional significance of the induction of Noxa. p53 has previously been shown to be non-functional in the T/C28a cell line and is absent by Western blotting in Saos2 cells, suggesting that the induction of Noxa is through a p53 independent mechanism. Western blotting and confocal microscopy showed that total beta-catenin protein is increased in both cell lines at the time of Noxa induction, with the bulk of the beta-catenin present in the nucleus. Transfection with the Tcf reporter vector pTOPFLASH confirms that treatment with MG132 leads to early increased transcriptional activity of beta-catenin in both T/C28a and Saos2 cells. However, although over-expression of transcriptionally active beta-catenin in T/C28a cells also induced apoptosis through a p53-independent mechanism, the levels of Noxa protein were unchanged, suggesting that beta-catenin mediated signaling and Noxa may play independent roles in MG132 induced apoptosis. In summary, our results demonstrate that MG132 induces the pro-apoptotic protein Noxa via a p53-independent mechanism that leads to caspase-dependent apoptosis. This is the first report showing that treatment with MG132 induces Noxa. This study also provides further evidence for a link between beta-catenin mediated signaling and the induction of apoptosis.

Herceptin sensitizes ErbB2-overexpressing cells to apoptosis by reducing antiapoptotic Mcl-1 expression

PURPOSE

Monoclonal antibodies, such as herceptin and trastuzumab, against the epidermal growth factor receptor ErbB2 (also known as HER2/neu) are an effective therapy for breast cancer patients with overexpression of ErbB2. Herceptin, in combination with standard chemotherapy, such as taxol or etoposide, gives a synergistically apoptotic response in breast tumors.

EXPERIMENTAL DESIGN

The mechanism underlying this synergy between chemotherapy and herceptin treatment is not well understood. Herein, we have determined that addition of herceptin, sensitized breast cancer cell lines MDA-MB-231 and MCF-7 to etoposide- or taxol-induced apoptosis.

RESULTS

This treatment resulted in reduced expression of ErbB2 and the antiapoptotic Bcl-2 family member Mcl-1 in MDA-MB-231 cells. Using antisense oligonucleotides against Mcl-1, MDA-MB-231 cells were rendered sensitive to etoposide-induced apoptosis similar to herceptin, but combined treatment of antisense against Mcl-1 and herceptin failed to give a significant increase in apoptosis. In 29 human breast tumors immunostained for ErbB2 and Mcl-1, we found that when ErbB2 was overexpressed, there was a corresponding increase in Mcl-1 expression.

DISCUSSION

Using murine fibroblasts that express human ErbB2, but no other ErbB family member (NE2), these cells showed resistance to both taxol- and etoposide-induced apoptosis compared with parental cells. In addition, NE2 cells preferentially express the antiapoptotic Bcl-2 family member Mcl-1 compared with parental cells, and treatment with herceptin reduces Mcl-1 expression. Taken together, these results suggest that herceptin sensitizes ErbB2-overexpressing cells to apoptosis by reducing antiapoptotic Mcl-1 protein levels.

Antiproliferation effects of oridonin on HPB-ALL cells and its mechanisms of action

Oridonin, an ent-kaurane diterpenoid derived from the herbal Rabdosia rubescens, has been recently reported to have antitumor effects on a large variety of cancer cells. The present study was undertaken to investigate the in vitro antiproliferation and apoptosis inducing effects of oridonin on HPB-ALL cell lines and its mechanisms of action. HPB-ALL cells in culture medium in vitro were treated with different concentrations of oridonin (16-56 micromol/L). MTT assay was used to detect the cell growth inhibitory rate, and the cell viability was assessed by the trypan blue dye-exclusion method. Cell apoptosis and the mitochondrial membrane potential (delta psi m) were investigated by flow cytometry (FCM), Hoechst 33258 staining, and DNA fragmentation analysis. The expression of caspase-3 and different apoptosis modulators, including Fas and Bcl-2 family members, was analyzed by Western blotting. The results revealed that oridonin could significantly inhibit the growth of HPB-ALL cells and cause apoptosis, and the suppression was both time- and dose-dependent. After treatment with oridonin for 48 hr, the percentage of disruption of delta psi m gradually increased in a dose-dependent manner along with marked changes of cell apoptosis, and necrotic cells increased remarkably after the cells were treated with oridonin for 72 hr; Western blotting showed cleavage of the caspase-3 zymogen protein (32 kDa) with the appearance of its 20-kDa subunit when apoptosis occurred; expression of Bcl-2 and Bcl-XL was downregulated remarkably while expression of Bax and Bid was upregulated concurrently after the cells were treated with oridonin for 24 hr. Of note, the expressions of Fas and other Bcl-2 family members including Bak and Bad remained constant before and after apoptosis occurred. We therefore conclude that oridonin has significant antiproliferation effects on HPB-ALL cells by induction of apoptosis as well as directly causing cell necrosis and that oridonin-induced apoptosis on HPB-ALL cells is mainly related to the disruption of delta psi m and activation of caspase-3 as well as downregulation of anti-apoptotic protein Bcl-2, Bcl-XL, and upregulation of pro-apoptotic proteins Bax and Bid. The results indicate that oridonin may serve as a potential antileukemia reagent.

Inhibition of CWR22Rnu1 tumor growth and PSA secretion in athymic nude mice by green and black teas

Cancer of the prostate gland (CaP), the most common invasive malignancy and a major cause of cancer related deaths in male population in the USA, is an ideal candidate disease for chemoprevention because it is typically detected in elderly population with a relatively slower rate of growth and progression. Many dietary phytochemicals are showing promising chemopreventive effects, at-least in pre-clinical models of CaP. Our published data in cell culture and animal studies, supported by the work from other laboratories, as well as epidemiological observations and case-control studies, suggest that polyphenols present in green tea possess CaP chemopreventive and possibly therapeutic effects. This present study was designed to compare CaP cancer chemopreventive effects of green tea polyphenols (GTP), water extract of black tea, and their major constituents epigallocatechin-3-gallate and theaflavins, respectively, in athymic nude mice implanted with androgen-sensitive human CaP CWR22Rnu1 cells. Our data demonstrated that the treatment with all the tea ingredients resulted in (i) significant inhibition in growth of implanted prostate tumors, (ii) reduction in the level of serum prostate specific antigen, (iii) induction of apoptosis accompanied with upregulation in Bax and decrease in Bcl-2 proteins, and (iv) decrease in the levels of VEGF protein. Furthermore, we also found that GTP (0.01 or 0.05% w/v; given after establishment of CWR22Rnu1 tumor) causes a significant regression of tumors suggesting therapeutic effects of GTP at human achievable concentrations.

HOXA1 is required for E-cadherin-dependent anchorage-independent survival of human mammary carcinoma cells

Forced expression of HOXA1 is sufficient to stimulate oncogenic transformation of immortalized human mammary epithelial cells and subsequent tumor formation. We report here that the expression and transcriptional activity of HOXA1 are increased in mammary carcinoma cells at full confluence. This confluence-dependent expression of HOXA1 was abrogated by incubation of cells with EGTA to produce loss of intercellular contact and rescued by extracellular addition of Ca2+. Increased HOXA1 expression at full confluence was prevented by an E-cadherin function-blocking antibody and attachment of non-confluent cells to a substrate by homophilic ligation of E-cadherin increased HOXA1 expression. E-cadherin-directed signaling increased HOXA1 expression through Rac1. Increased HOXA1 expression consequent to E-cadherin-activated signaling decreased apoptotic cell death and was required for E-cadherin-dependent anchorage-independent proliferation of human mammary carcinoma cells. HOXA1 is therefore a downstream effector of E-cadherin-directed signaling required for anchorage-independent proliferation of mammary carcinoma cells.

BETA.-D-Xylopyranosyl-(1.RAR.3)-.BETA.-D-glucuronopyranosyl Echinocystic Acid Isolated from the Roots of Codonopsis lanceolata Induces Caspase-Dependent Apoptosis in Human Acute Promyelocytic Leukemia HL-60 Cells

We previously demonstrated that beta-D-xylopyranosyl-(1-->3)-beta-D-glucuronopyranosyl echinocystic acid (codonoposide 1c), a biologically active compound isolated from the roots of Codonopsis lanceolata, is cytotoxic to cancer cells. In the present study, we investigated the effects of codonoposide 1c on the induction of apoptosis, and its putative action pathway in HL-60 human promyelocytic leukemia cells. Codonoposide 1c-treated HL-60 cells displayed several features of apoptosis, including DNA fragmentation, formation of DNA ladders by agarose gel electrophoresis, and externalization of annexin-V targeted phosphatidylserine (PS) residues. We observed that codonoposide 1c caused activation of caspase-8, caspase-9, and caspase-3. A broad caspase inhibitor (z-VAD-fmk), caspase-8 inhibitor (z-IETD-fmk), and caspase-3 inhibitor (z-DEVD-fmk) almost completely suppressed codonoposide 1c-induced DNA fragmentation. We further found that codonoposide 1c induces mitochondrial translocation of Bid from cytosol, reduction of cytosolic Bax, and cytochrome c release from mitochondria. Interestingly, codonoposide 1c also triggered the mitochondrial release of Smac/DIABLO (second mitochondria-derived activator of caspases/direct inhibitor of apoptosis-binding protein with a low isoelectric point) into cytosol, and a reduction in X-linked inhibitor of apoptosis protein (XIAP). Taken together, our data indicate that codonoposide 1c is a potent inducer of apoptosis and facilates its activity via Bid cleavage and translocation to mitochondria, Bax reduction in cytosol, release of cytochrome c and Smac/DIABLO into the cytosol, and subsequently caspase activation, providing a potential mechanism for the cytotoxic activity of codonoposide 1c.