Involvement of both intrinsic and extrinsic pathways in IFN-γ-induced apoptosis that are enhanced with cisplatin

Extrinsic apoptosis and senescence involved in growth kinetics of seminoma to cisplatin

Seminoma is the most common type of testicular germ cell tumour and is highly sensitive to cisplatin therapy, which has not been fully elucidated. In this study, we comprehensively monitored dynamic changes of TCam-2 cells after cisplatin treatment. At an early stage, we found that both low and high concentrations of cisplatin induced the S-phase arrest in TCam-2 cells. By contrast, the G0G1 arrest was caused by cisplatin in teratoma NTERA-2 cells. Afterwards, high concentrations of cisplatin promoted the extrinsic apoptosis and high expressions of related genes (Fas/FasL-caspase-8/-3) in TCam-2 cells. However, when decreasing the cisplatin, the apoptotic cells were significantly reduced, and accompanied by cells showing senescence-like morphology, positive SA-β-gal staining and up-regulation of senescence-related genes (p53, p21 and p16). Furthermore, the cell cycle analysis revealed that most of the senescent TCam-2 cells were irreversibly arrested in the G2M phase. G2M arrest was also observed in NTERA-2 cells treated with a low concentration of cisplatin, while no senescence-related phenotype was discovered. In addition, we detected the γ-H2AX, a DNA damage marker protein, and reactive oxygen species (ROS) and found both of which were elevated with the increase of cisplatin in TCam-2 cells. In conclusion, the extrinsic apoptosis and senescence are involved in the growth kinetics of TCam-2 cells to cisplatin, which provide some implications for studies on cisplatin and seminoma.

IFN-γ inhibits ovarian cancer progression via SOCS1/JAK/STAT signaling pathway

PURPOSE

Ovarian cancer (OC) is a common malignancy, and IFN-γ, a multifunctional cytokine, is unveiled to impede the multiplication and enhance apoptosis in diverse tumor cells in previous research. Nonetheless, its function and mechanism in OC are blurred.

METHODS

OC cell lines SKOV3 and OVCAR3 were dealt with different concentrations (0-40 ng/ml) of IFN-γ. CCK-8 experiment was utilized to examine cell multiplication; Flow cytometry was executed to detect apoptosis and cell cycle; Wound healing assay was utilized to detect cell migration; and Transwell experiment was implemented to examine cell invasion. qRT-PCR analysis was applied to detect STAT5, STAT3, JAK2 and JAK3 mRNA expression in OC cell lines. Western blot experiment was applied to detect the protein and phosphorylation levels of SOCS1, STAT5 and STAT3.

RESULTS

IFN-γ suppressed OC cell multiplication in a concentration-dependent manner. Relative to the control group, IFN-γ restrained OC cell migration, invasion, enhanced apoptosis and prevented cell transformation from G0/G1 to S phase. Further analysis revealed that IFN-γ up-modulated SOCS1 expression and impeded STAT5 and STAT3 protein phosphorylation levels, and knockdown of SOCS1 partially counteracted the inhibitory effect of IFN-γ on STAT5 and STAT3 protein phosphorylation levels.

CONCLUSION

IFN-γ represses OC progression by facilitating SOCS1 to suppress STAT3 and STAT5 protein phosphorylation.

Phosphatidylcholine causes adipocyte-specific lipolysis and apoptosis in adipose and muscle tissues

Phosphatidylcholine (PPC) formula has been therapeutically used to reduce areas of localized fat. However, no single research has been carried out on its effect on a variety of cells in adipose and muscle tissues. Herein, the current study aimed to explore the activity of PPC on different cells in adipose and muscle tissues and to investigate the molecular mechanisms contributing to the effects of PPC on lipolysis and apoptosis. mRNA expression levels of various genes were measured by quantitative real-time PCR. Protein expression levels were observed through Western blotting and cell viability was measured by MTT assay. Lipolysis and caspase 3 activity assay were performed using commercial kits. PPC induces lipolysis and apoptosis in adipocytes (3T3-L1), but not in the other tested cells, including skeletal muscle cells (C2C12 myocytes), endothelial cells (HUVEC), and fibroblasts (BJ). The possible role of TNFα and IL-1β-mediated pathways on the effects of PPC was also revealed. We confirmed that treatment with PPC caused lipolysis and apoptosis in a dose-dependent manner (only in 3T3-L1 adipocytes). The effect of PPC observed in 3T3-L1 adipocytes was not evident in C2C12 myocytes, HUVEC, and fibroblasts. PPC also increased TNFα and IL-1β expression and release in 3T3-L1 adipocytes in a dose-dependent fashion, but not in C2C12 myocytes, HUVEC, and BJ. Suppression of TNFα or IL-1β reversed PPC-induced lipolysis and apoptosis in 3T3-L1 adipocytes, suggesting that PPC could promote adipocyte-specific lipolysis and apoptosis through TNFα and IL-1β-mediated signaling. We conclude that the specific activity of PPC on adipocyte in adipose without other tissue damages can be an effective approach for melting lipid.

Tat is a multifunctional viral protein that modulates cellular gene expression and functions

The human immunodeficiency virus type I (HIV-1) has developed several strategies to condition the host environment to promote viral replication and spread. Viral proteins have evolved to perform multiple functions, aiding in the replication of the viral genome and modulating the cellular response to the infection. Tat is a small, versatile, viral protein that controls transcription of the HIV genome, regulates cellular gene expression and generates a permissive environment for viral replication by altering the immune response and facilitating viral spread to multiple tissues. Studies carried out utilizing biochemical, cellular, and genomic approaches show that the expression and activity of hundreds of genes and multiple molecular networks are modulated by Tat via multiple mechanisms.

Highly functionalized pyrrolidine analogues: stereoselective synthesis and caspase-dependent apoptotic activity

Spiropyrrolidines were synthesized employing a new class of azomethine ylide for the first time and were tested for their anticancer activity, where the cell death mechanism revealed that it is occurring through the caspase-3 dependent pathway.

Improved therapeutic efficacy of mammalian expressed-recombinant interferon gamma against ovarian cancer cells

Human interferon gamma (hIFNγ) affects tumour cells and modulates immune responses, showing promise as an anti-cancer biotherapeutic. This study investigated the effect of glycosylation and expression system of recombinant hIFNγ in ovarian carcinoma cell lines, PEO1 and SKOV3. The efficacy of E. coli- and mammalian-expressed hIFNγ (hIFNγ-CHO and HEK293, glycosylated/de-glycosylated) on cytostasis, cell death (MTT, and Guava-ViaCount^® flow-cytometry) and apoptotic signalling (Western blot of Cdk2, histone H3, procaspase-3, FADD, cleaved PARP, and caspase-3) was examined. Hydrophilic Interaction Liquid Chromatography determined the structure of N-linked glycans present in HEK293-expressed hIFNγ (hIFNγ-HEK). PEO1 was more sensitive to hIFNγ than SKOV3, but responses were dose-dependent and expression platform/glycosylation status-independent, whereas SKOV3 responded to mammalian-expressed hIFNγ in a dose-independent manner, only. Complex-type oligosaccharides dominated the N-glycosylation pattern of hIFNγ-HEK with some terminal sialylation and core fucosylation. Cleaved PARP and cleaved caspase-3 were not detected in either cell line, but FADD was expressed in SKOV3 with levels increased following treatment. In conclusion, hIFNγ did not induce apoptosis in either cell line. Mammalian- expressed hIFNγ increased cell death in the drug-resistant SKOV3. The presence of FADD in SKOV3, which may inhibit apoptosis through activation of NF-κB, could serve as a novel therapeutic target.

Cytokine Regulation of Metastasis and Tumorigenicity

The human body combats infection and promotes wound healing through the remarkable process of inflammation. Inflammation is characterized by the recruitment of stromal cell activity including recruitment of immune cells and induction of angiogenesis. These cellular processes are regulated by a class of soluble molecules called cytokines. Based on function, cell target, and structure, cytokines are subdivided into several classes including: interleukins, chemokines, and lymphokines. While cytokines regulate normal physiological processes, chronic deregulation of cytokine expression and activity contributes to cancer in many ways. Gene polymorphisms of all types of cytokines are associated with risk of disease development. Deregulation RNA and protein expression of interleukins, chemokines, and lymphokines have been detected in many solid tumors and hematopoetic malignancies, correlating with poor patient prognosis. The current body of literature suggests that in some tumor types, interleukins and chemokines work against the human body by signaling to cancer cells and remodeling the local microenvironment to support the growth, survival, and invasion of primary tumors and enhance metastatic colonization. Some lymphokines are downregulated to suppress tumor progression by enhancing cytotoxic T cell activity and inhibiting tumor cell survival. In this review, we will describe the structure/function of several cytokine families and review our current understanding on the roles and mechanisms of cytokines in tumor progression. In addition, we will also discuss strategies for exploiting the expression and activity of cytokines in therapeutic intervention.

Combination therapy induces unfolded protein response and cytoskeletal rearrangement leading to mitochondrial apoptosis in prostate cancer

Development of therapeutic resistance is responsible for most prostate cancer (PCa) related mortality. Resistance has been attributed to an acquired or selected cancer stem cell phenotype. Here we report the histone deacetylase inhibitor apicidin (APC) or ER stressor thapsigargin (TG) potentiate paclitaxel (TXL)-induced apoptosis in PCa cells and limit accumulation of cancer stem cells. TXL-induced responses were modulated in the presence of TG with increased accumulation of cells at G1-phase, rearrangement of the cytoskeleton, and changes in cytokine release. Cytoskeletal rearrangement was associated with modulation of the cytoplasmic and mitochondrial unfolded protein response leading to mitochondrial dysfunction and release of proapoptotic proteins from mitochondria. TXL in combination with APC or TG enhanced caspase activation. Importantly, TXL in combination with TG induced caspase activation and apoptosis in X-ray resistant LNCaP cells. Increased release of transforming growth factor-beta (TGF-β) was observed while phosphorylated β-catenin level was suppressed with TXL combination treatments. This was accompanied by a decrease in the CD44(+)CD133(+) cancer stem cell-like population, suggesting treatment affects cancer stem cell properties. Taken together, combination treatment with TXL and either APC or TG induces efficient apoptosis in both proliferating and cancer stem cells, suggesting this therapeutic combination may overcome drug resistance and recurrence in PCa.

Antitumor potential of a synthetic interferon-alpha/PLGF-2 positive charge peptide hybrid molecule in pancreatic cancer cells

Pancreatic cancer is the most aggressive malignant disease, ranking as the fourth leading cause of cancer-related death among men and women in the United States. Interferon alpha (IFNα) has been used to treat pancreatic cancer, but its clinical application has been significantly hindered due to the low antitumor activity. We used a "cDNA in-frame fragment library" screening approach to identify short peptides that potentiate the antitumor activity of interferons. A short positively charged peptide derived from the C-terminus of placental growth factor-2 (PLGF-2) was selected to enhance the activity of IFNα. For this, we constructed a synthetic interferon hybrid molecule (SIFα) by fusing the positively charged PLGF-2 peptide to the C-terminus of the human IFNα. Using human pancreatic cell lines (ASPC and CFPAC1) as a model system, we found that SIFα exhibited a significantly higher activity than did the wild-type IFNα in inhibiting the tumor cell growth. The enhanced activity of the synthetic SIFα was associated with the activation of interferon pathway target genes and the increased binding of cell membrane receptor. This study demonstrates the potential of a synthetic SIFα as a novel antitumor agent.

Adenovirus-mediated interferon-γ gene therapy induced human pancreatic carcinoma Capan-2 cell apoptosis in vitro and in vivo

Pancreatic cancer is one of the most lethal human malignancies with a very low 5-year survival rate, which highlights urgent needs for more effective therapeutic strategies. In this study, we examined the potential therapeutic effects of an adenovirus encoding human interferon gamma (Ad-IFNγ) on pancreatic carcinoma cells Capan-2 in vitro and in vivo. The results indicated that Ad-IFNγ could significantly inhibit tumor cell growth via inducing cell apoptosis. After infection, IFNγ expressed durably and stably in xenografts, predominantly in tumor tissue, while much less in blood and liver. Thus, adenovirus-mediated intratumoral injection of human IFNγ gene could be an effective gene therapeutic system for the treatment of pancreatic carcinoma.

Adenovirus-mediated delivery of interferon-γ gene inhibits the growth of nasopharyngeal carcinoma

Background

Interferon-γ (IFN-γ) is regarded as a potent antitumor agent, but its clinical application is limited by its short half-life and significant side effects. In this paper, we tried to develop IFN-γ gene therapy by a replication defective adenovirus encoding the human IFN-γ (Ad-IFNγ), and evaluate the antitumoral effects of Ad-IFNγ on nasopharyngeal carcinoma (NPC) cell lines in vitro and in xenografts model.

Methods

The mRNA levels of human IFN-γ in Ad-IFNγ-infected NPC cells were detected by reverse transcription-polymerase chain reaction (RT-PCR), and IFN-γ protein concentrations were measured by enzyme-linked immunosorbent assay (ELISA) in the culture supernatants of NPC cells and tumor tissues and bloods of nude mice treated with Ad-IFNγ. The effects of Ad-IFNγ on NPC cell proliferation was determined using MTT assay, cell cycle distribution was determined by flow cytometry analysis for DNA content, and cells apoptosis were analyzed by Annexin V-FITC/7-AAD binding assay and hoechst 33342/PI double staining. The anti-tumor effects and toxicity of Ad-IFNγ were evaluated in BALB/c nude mice carrying NPC xenografts.

Results

The results demonstrated that Ad-IFNγ efficiently expressed human IFN-γ protein in NPC cell lines in vitro and in vivo. Ad-IFNγ infection resulted in antiproliferative effects on NPC cells by inducing G1 phase arrest and cell apoptosis. Intratumoral administration of Ad-IFNγ significantly inhibited the growth of CNE-2 and C666-1 cell xenografts in nude mice, while no significant toxicity was observed.

Conclusions

These findings indicate IFN-γ gene therapy mediated by replication defective adenoviral vector is likely a promising approach in the treatment of nasopharyngeal carcinoma.

Gallium compound GaQ(3) -induced Ca(2+) signalling triggers p53-dependent and -independent apoptosis in cancer cells

BACKGROUND AND PURPOSE A novel anti-neoplastic gallium complex GaQ(3) (KP46), earlier developed by us, is currently in phase I clinical trial. GaQ(3) induced S-phase arrest and apoptosis via caspase/PARP cleavage in a variety of cancers. However, the underlying mechanism of apoptosis is unknown. Here, we have explored the mechanism(s) of GaQ(3) -induced apoptosis in cancer cells, focusing on p53 and intracellular Ca(2+) signalling. EXPERIMENTAL APPROACH GaQ(3) -induced cytotoxicity and apoptosis were determined in cancer cell lines, with different p53 status (p53(+/+) , p53(-/-) and p53 mutant). Time course analysis of intracellular Ca(2+) calcium release, p53 promoter activation, p53-nuclear/cytoplasmic movements and reactive oxygen species (ROS) were conducted. Ca(2+) -dependent formation of the p53-p300 transcriptional complex was analysed by co-immunoprecipitation and chromatin immunoprecipitation. Ca(2+) signalling, p53, p300 and ROS were serially knocked down to study Ca(2+) -p53-ROS ineractions in GaQ(3) -induced apoptosis. KEY RESULTS GaQ(3) triggered intracellular Ca(2+) release stabilizing p53-p300 complex and recruited p53 to p53 promoter, leading to p53 mRNA and protein synthesis. p53 induced higher intracellular Ca(2+) release and ROS followed by activation of p53 downstream genes including those for the micro RNA mir34a. In p53(-/-) and p53 mutant cells, GaQ(3) -induced Ca(2+) -signalling generated ROS. ROS further increased membrane translocation of FAS and FAS-mediated extrinsic apoptosis. CONCLUSIONS AND IMPLICATIONS This study disclosed a novel mechanism of Ca(2+) -signalling-mediated p53 activation and ROS up-regulation. Understanding the mechanism of GaQ(3) -induced apoptosis will help establish this gallium-based organic compound as a potent anti-cancer drug.

Silencing of Apoptosis-Inducing factor and poly(ADP-ribose) glycohydrolase reveals novel roles in breast cancer cell death after chemotherapy

Background

Cell death induced by poly(ADP-ribose) (PAR) and mediated by apoptosis-inducing factor (AIF) is well-characterized in models of ischemic tissue injury, but their roles in cancer cell death after chemotherapy are less understood.

Methods

Here we investigated the roles of PAR and AIF by RNA interference (RNAi) in MDA-MB-231 and MCF-7 breast adenocarcinoma cells after chemotherapy. Differences in effects were statistically tested by analysis-of-variance and unpaired student’s t-test.

Results

Silencing of AIF by RNAi led to decreased MDA-MB-231 and MCF-7 breast cancer cell death after chemotherapy, which demonstrates a critical role for AIF. RNAi silencing of PAR glycohydrolase (PARG), the primary enzyme that catalyzes the hydrolysis of PAR, led to increased PAR levels but decreased cell death. Further investigation into the possible role of PAR in apoptosis revealed decreased caspase-3/7/8/9 activity in PARG-null cells. Interestingly, the pharmacologic inhibition of caspase activity in PARG-silenced breast cancer cells led to increased cell death after chemotherapy, which indicates that an alternative cell death pathway is activated due to elevated PAR levels and caspase inhibition. AIF silencing in these cells led to profound protection from chemotherapy, which demonstrates that the increased cell death after PARG silencing and caspase inhibition was mediated by AIF.

Conclusions

The results show a role for AIF in breast cancer cell death after chemotherapy, the ability of PAR to regulate caspase activity, and the ability of AIF to substitute as a primary mediator of breast cancer cell death in the absence of caspases. Thus, the induction of cell death by PAR/AIF may represent a novel strategy to optimize the eradication of breast tumors by activating an alternative cell death pathway.

Chitooligosaccharides and N-acetyl-D-glucosamine stimulate peripheral blood mononuclear cell-mediated antitumor immune responses

The aim of the present study was to evaluate the anticancer effects of chitooligosaccharides (COS) and N-acetyl-D-glucosamine (NAG), as well as to investigate the possible mechanisms involved. MTT assay and flow cytometry were used to evaluate the effect of various concentrations of COS and NAG on the proliferation and differentiation of peripheral blood mononuclear cells (PBMCs). In addition, sarcoma 180 cells were transplanted into mice to establish a tumor model. COS and NAG were administered by gavage of various doses. The tumor inhibition rate, thymus and spleen indexes, natural killer (NK) cell activity, and interleukin-2 (IL-2) and interferon-γ (IFN-γ) serum levels were detected. Vascular endothelial growth factor (VEGF) expression levels, an important marker of angiogenesis, were also detected. As shown by immunohistochemistry, VEGF mRNA expression was decreased following treatment with COS and NAG, indicating that COS and NAG have an inhibitory effect on the expression of VEGF. The results from this study indicate that COS administered at a dose of 100 mg/kg and NAG at a dose of 300 mg/kg or 500 mg/kg can not only promote the differentiation of PBMCs and the secretion of IL-2 and IFN-γ, but can also inhibit the expression of VEGF mRNA in sarcoma 180 tumors. Our results show that the antitumor and immunoregulatory effects of COS and NAG are dose-dependent. Furthermore, the antitumor effect is achieved by the improvement of immunoregulation indirectly.

Micro-calpain regulates caspase-dependent and apoptosis inducing factor-mediated caspase-independent apoptotic pathways in cisplatin-induced apoptosis

Cisplatin, an effective anticancer agent, can induce tumor cell apoptosis via caspase-dependent and-independent pathways. However, the precise mechanism that regulates the pathways remains unclear. In this study, we showed that micro-calpain mediated both caspase-dependent and-independent pathways during cisplatin-induced apoptosis in human lung adenocarcinoma cells. After cisplatin treatment, calpain activation, as measured by a fluorescent substrate, was an early event, taking place well before apoptosis inducing factor (AIF) release and caspase-9/-3 activation. Confocal imaging of cells transfected with AIF-GFP demonstrated that AIF release occurred about 9 hr after cisplatin treatment. The increase of micro-calpain activity proved to be a crucial event in the apoptotic machinery, as demonstrated by the significant protection of cell death in samples suppressed the endogenous micro-calpain expression level, as well as cotreated with the calpain inhibitors, calpeptin and PD150606. Inhibition of mu-calpain not only significantly reduced caspase-9/-3 activities but also completely blocked AIF redistribution. Our study also showed that endogenous mitochondrial micro-calpain could directly induce the truncation and release of AIF, while caspases and cathepsins were not necessary for this process. In conclusion, the study demonstrated that activation of micro-calpain played an essential role in regulating both caspase-dependent and AIF-mediated caspase-independent apoptotic pathways in cisplatin-induced apoptosis.

Cisplatin-induced hair cell death requires STAT1 and is attenuated by epigallocatechin gallate

Cisplatin is a chemotherapy drug that frequently causes auditory impairment due to the death of mechanosensory hair cells. Cisplatin ototoxicity may result from oxidative stress, DNA damage, and inflammatory cytokines. The transcription factor STAT1, an important mediator of cell death, can regulate all of these processes in other cell types. We used cultured utricles from mature Swiss Webster mice to investigate the role of STAT1 in cisplatin-induced hair cell death. We show that STAT1 phosphorylation is an early event in both hair cells and support cells after exposure of utricles to cisplatin. STAT1 phosphorylation peaked after 4 h of cisplatin exposure and returned to control levels by 8 h of exposure. The STAT1 inhibitor epigallocatechin gallate (EGCG) attenuated STAT1 phosphorylation in cisplatin-treated utricles and resulted in concentration-dependent increases in hair cell survival at 24 h postexposure. Furthermore, we show that utricular hair cells from STAT1-deficient mice are resistant to cisplatin toxicity. EGCG failed to provide additional protection from cisplatin in STAT1-deficient mice, further supporting the hypothesis that the protective effects of EGCG are due to its inhibition of STAT1. Treatment with IFN-gamma, which also causes STAT1 activation, also induced hair cell death in wild-type but not STAT1-deficient mice. These results show that STAT1 is required for maximal cisplatin-induced hair cell death in the mouse utricle and suggest that treatment with EGCG may be a useful strategy for prevention of cisplatin ototoxicity.

IFN-gamma induces apoptosis in HL-60 cells through decreased Bcl-2 and increased Bak expression

Interferons (IFNs) are pleiotropic cytokines responsible for inducing innate and adaptive immunities against a wide range of viruses and other microbial pathogens. In addition, IFNs also exert antitumor activities due to their antiproliferative, immunomodulatory, proapoptotic functions. In the last decades, the successful clinical application of IFNs for treatment of cancer, particularly leukemia, has improved the quality and longevity of life for many patients. The induction of tumor cell apoptosis by IFNs is believed to contribute, at least in part, to the beneficial effects. IFN subtypes, such as IFN-alpha, IFN-beta, and IFN-gamma, induce apoptosis through cell type-specific signaling pathways, and several putative IFN-stimulated genes (ISGs) with proapoptotic functions have been identified. Here, we analyzed the ability of IFN-alpha, IFN-beta, or IFN-gamma to induce apoptosis in several malignant hematologic cell lines. We found that treatment with IFN-gamma, but not IFN-alpha, or IFN-beta, specifically induces HL-60 leukemia cells to undergo apoptosis. Roughly 30% of HL-60 cells treated for 48 h with IFN-gamma, but not IFN-gamma, or IFN-beta, underwent apoptosis as monitored by annexin V labeling to determine changes in phosphatidylserine (PS) asymmetry and TUNEL assay to detect DNA fragmentation. Consistent with these results, treatment with IFN-gamma, but not IFN-alpha or IFN-beta, induced the release of cytochrome c, activation of caspase-3, and cleavage of poly (ADP-ribose) polymerase (PARP), a well-characterized caspase-3 substrate. Further investigation into the potential mechanism responsible for mitochondrial disruption revealed that treatment with IFN-gamma caused decreased levels of Bcl-2 and increased levels of Bak. This study thus provides the basis for additional research to uncover the molecular mechanism by which IFN-gamma regulates the expression of Bcl-2 family members in various cell types.

Randomized phase 3 trial of interferon gamma-1b plus standard carboplatin/paclitaxel versus carboplatin/paclitaxel alone for first-line treatment of advanced ovarian and primary peritoneal carcinomas: results from a prospectively designed analysis of progression-free survival

OBJECTIVES

Interferon gamma (IFN-gamma) is a pleiotropic cytokine with antiproliferative, immunostimulatory, and chemosensitization properties. This trial was designed to evaluate IFN-gamma 1b plus carboplatin and paclitaxel in treatment-naive ovarian cancer (OC) and primary peritoneal carcinoma (PPC) patients.

METHODS

Eligible patients were randomized to 6 cycles of carboplatin/paclitaxel every 3 weeks or the same in combination with IFN-gamma 1b (100 microg 3x/wk subcutaneously). The primary endpoint was overall survival (OS) time (target hazard ratio (HR)=0.77). Secondary endpoints included progression-free survival (target HR=0.7), based on blinded review of serial imaging scans, physical exams, and CA-125 levels.

RESULTS

847 patients were enrolled (OC 774, PPC 73) in Europe (n=539) and North/South America (n=308) from January 29, 2002 to March 31, 2004 and stratified according to: optimal debulking (n=271) versus suboptimal debulking with plans for interval debulking (PID) (n=238) or no PID (n=338). The study stopped early following a protocol-defined second interim analysis which revealed significantly shorter OS time in patients receiving IFN-gamma 1b plus chemotherapy compared to chemotherapy alone (1138 days vs. not estimable, HR=1.45, 95% CI=1.15-1.83). At the time of the analysis, 169 of 426 (39.7%) patients in the IFN-gamma 1b plus chemotherapy group had died compared to 128 of 421 (30.4%) in the chemotherapy alone group. Serious adverse events were more common in the IFN-gamma 1b plus chemotherapy group (48.5% vs. 35.4%), primarily due to a higher incidence of serious hematological toxicities (34.5% vs. 22.7%).

CONCLUSIONS

Treatment with IFN-gamma 1b in combination with carboplatin/paclitaxel does not have a role in the first-line treatment of advanced ovarian cancer.

Regulation of apoptosis-inducing factor-mediated, cisplatin-induced apoptosis by Akt

Cisplatin is a first-line chemotherapeutic for ovarian cancer, although chemoresistance limits treatment success. Apoptosis, an important determinant of cisplatin sensitivity, occurs via caspase-dependent and -independent mechanisms. Activation of the protein kinase Akt, commonly observed in ovarian tumours, confers resistance to ovarian cancer cells via inhibition of caspase-dependent apoptosis. However, the effect of Akt on cisplatin-induced, caspase-independent apoptosis remains unclear. We show that in chemosensitive ovarian cancer cells, cisplatin induces the mitochondrial release and nuclear translocation of apoptosis-inducing factor (AIF), a mediator of caspase-independent apoptosis, and AIF-dependent apoptosis. Cisplatin failed to induce these effects in the chemoresistant variant cells. Overexpression of AIF sensitised resistant cells to cisplatin-induced apoptosis. Finally, activation of Akt attenuated the cisplatin-induced mitochondrial release and nuclear accumulation of AIF and apoptosis in chemosensitive cells, whereas inhibition of Akt activity facilitated these effects and sensitised chemoresistant cells to AIF-dependent, cisplatin-induced apoptosis. These results suggest that cisplatin-induced apoptosis proceeds, in part, via a caspase-independent mechanism involving AIF, and that Akt activation confers resistance to cisplatin-induced apoptosis by blocking this pathway. These results provide insights into the molecular mechanism of chemoresistance, and suggest that inhibition of Akt activity may represent a novel therapeutic approach to the treatment of cisplatin-resistant ovarian cancer.

Minicircle-IFNgamma induces antiproliferative and antitumoral effects in human nasopharyngeal carcinoma

PURPOSE

The aims of this work were to investigate the antitumor effect of IFNgamma gene transfer on human nasopharyngeal carcinoma (NPC) and to assess the potential of minicircle vector for antitumor gene therapy.

EXPERIMENTAL DESIGN

We developed a recombinant minicircle vector carrying the human IFNgamma gene and evaluated the effects of minicircle-mediated IFNgamma gene transfer on NPC cell lines in vitro and on xenografts in vivo.

RESULTS

Relative to p2PhiC31-IFNgamma, minicircle-mediated IFNgamma gene transfer in vitro resulted in 19- to 102-fold greater IFNgamma expression levels in transfected cells (293, NIH 3T3, CNE-1, CNE-2, and C666-1) and inhibited the growth of CNE-1, CNE-2, and C666-1 cells more efficiently, reducing relative growth rates to 7.1 +/- 1.6%, 2.7 +/- 1.0%, and 6.1 +/- 1.6%, respectively. Flow cytometry and caspase-3 activity assays suggested that the antiproliferative effects of IFNgamma gene transfer on NPC cell lines could be attributed to G(0)-G(1) arrest and apoptosis. Minicircle-mediated intratumoral IFNgamma expression in vivo was 11 to 14 times higher than p2PhiC31-IFNgamma in CNE-2- and C666-1-xenografted mice and lasted for 21 days. Compared with p2PhiC31-IFNgamma treatment, minicircle-IFNgamma treatment significantly increased survival and achieved inhibition rates of 77.5% and 83%, respectively.

CONCLUSIONS

Our data indicate that IFNgamma gene transfer exerts antiproliferative effects on NPC cells in vitro and leads to a profound antitumor effect in vivo. Minicircle-IFNgamma is more efficient than corresponding conventional plasmids due to its capability of mediating long-lasting high levels of IFNgamma gene expression. Therefore, minicircle-mediated IFNgamma gene transfer is a promising novel approach in the treatment of NPC.

Utilization of Interferon in Gynecologic and Breast Cancer

The usual treatment of gynecologic cancer has been surgery, chemotherapy and radiotherapy. New therapies are being developed to improve efficacy of treatment. Interferons are inducible secretory glycoproteins that have immunomodulatory, antiviral, anti-angiogenic and anti-proliferative effects. Their potential antitumor effect has been demonstrated in many studies. Some patients obtain beneficial effects; in other patients the treatment failure can occur. IFNs can modulate the immune response and inhibition of tumor angiogenesis. When any alteration in gene expression occurs, there is modulation of the receptors of other cytokines and enzymes that control cell function. These alterations can influence the differentiation, cell proliferation rate and apoptosis. The molecular mechanisms that control apoptotic cell death can be improved through cancer management using IFN in single, combination or adjuvant treatment. Malignant cells generally present defects in programmed cell death and apoptosis. Immunomodulation and angiogenesis inhibition are indirect antitumor mechanisms mediated by apoptosis. With regard to immunomodulation, IFNs can have antitumor effects through increases in cytotoxic T cells, natural killer cells and dendritic cells. Angiogenesis inhibition can result from endothelial cell apoptosis. This factor is important in inhibiting tumor genesis and forming metastases. The aim of this review is to discuss the role of Interferon in the treatment of gynecologic malignancies/breast cancer and mechanisms of action.

Immune escape associated with functional defects in antigen-processing machinery in head and neck cancer

Recent revival of interest in the role of immune surveillance in the pathogenesis and control of malignant diseases has focused attention on escape mechanisms used by tumor cells to evade immune recognition. Defects in the host's tumor antigen-specific immune responses and abnormalities in tumor cell expression of HLA class I molecules and tumor antigen are known to contribute to tumor progression. However, the mechanism(s) responsible for the lack of tumor cell recognition by functional HLA class I antigen-restricted, tumor antigen-specific CTLs despite expression of the restricting HLA class I allele and targeted tumor antigen by tumor cells remain(s) unexplained. In squamous cell carcinomas of the head and neck (SCCHN), this type of tumor escape is a rule rather than the exception. Here, we discuss evidence pointing to functional defects in the antigen-processing machinery as one mechanism underlying resistance of SCCHN cells to recognition and lysis by HLA class I antigen-restricted, tumor antigen-specific CTL. In addition, based on the restoration by IFN-gamma of SCCHN cell sensitivity to recognition by these CTL, we suggest strategies that may improve the clinical course of the disease by enhancing susceptibility of malignant cells to immune recognition.

Loss of IFN gamma receptor is an independent prognostic factor in ovarian cancer

PURPOSE

There is evidence that IFN gamma plays an important role in ovarian cancer development. IFN gamma produces numerous antitumor effects and it may be evasion of these effects which allows tumor progression. We postulate that genetic instability in tumor cells may lead to modulation of expression of the IFN gamma receptor, thus leading to altered tumor biology and patient prognosis. This hypothesis would support the theory of immunoediting in ovarian cancer.

EXPERIMENTAL DESIGN

Using tissue microarray technology of 339 primary ovarian cancers, the expression of IFN gamma receptor was assessed immunohistochemically. Coupled to a comprehensive database of clinicopathologic variables, its effect on these factors was studied.

RESULTS

Tumors expressing high levels of IFN gamma receptor had significantly improved survival (P=0.017) compared with tumors expressing low levels of the receptor; this was also seen with complete receptor loss (P=0.014). Factors shown to predict prognosis independently of each other were the following: age, International Federation of Gynecologists and Obstetricians stage, and the absence of macroscopic disease after surgery. The level of IFN gamma receptor expression and complete receptor loss were independently predictive of prognosis on multivariate analysis. There was no correlation between receptor status and any of the standard clinicopathologic variables.

CONCLUSIONS

Loss of IFN gamma receptor independently predicts poor prognosis in ovarian cancer. Loss of receptor expression may be responsible for the limited success in the therapeutic use of IFN gamma in ovarian cancer trials and highlights a subgroup of high expressing IFN gamma receptor tumors which are more likely to be susceptible to such treatments.

Iressa induces cytostasis and augments Fas-mediated apoptosis in acinic cell adenocarcinoma overexpressing HER2/neu

Understanding the role of signal transduction in regulating pathways responsible for cell growth, survival and apoptosis is critical for cancer therapy. We developed and characterized a HER2/neu and Fas overexpressing cell line (BNT.888 ACA2) from a salivary gland adenocarcinoma that arose in a HER2/neu transgenic mouse. We evaluated the effects of Iressa on signal transduction networks downstream of the activated HER2 and the impact on proliferation, cell cycle and apoptosis. Iressa treatment diminished phosphorylation of the HER2/neu and EGFR. Phosphorylation of STAT-3 also decreased and mitogenic signaling through the MAPK pathways was greatly reduced. Cyclin D1 levels decreased, and cells were arrested in G0 and failed to enter S-phase because of hypophosphorylation of Rb and to traverse the G2M checkpoint because of degradation of cyclin B1. Cytostasis occurred within 48 hr at 250-500 nM Iressa. Levels of proapoptotic factors (bim and bax) increased and levels of antiapoptotic factors (bcl-2 and bcl-xL) decreased in a dose-dependent manner. Higher doses of Iressa diminished phosphorylation of Akt slightly, but failed to induce apoptosis. Fas antibody was a potent agonist of apoptosis. Pretreatment with Iressa (1 microM, 24 hr) greatly enhanced Fas-mediated apoptosis as determined by Annexin V binding, cleavage of caspase-3 and PARP. Augmentation of apoptosis was associated with increased Fas expression and membrane localization. Iressa pretreatment increased bid activation, cleavage of caspases -3, -9 and -12 and stress signaling via c Jun. These data showing that Iressa induces cytostasis and primes the extrinsic (Fas) and intrinsic (mitochondrial and endoplasmic reticulum) apoptotic pathways should lead to the development of novel therapeutic targets and strategies.