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The role of tweety homolog 3 (TTYH3) has been studied in several cancers, including hepatocellular carcinoma, cholangiocarcinoma, and gastric cancer. The results showed that TTYH3 is highly expression in cervical cancer tissues and cells and high TTYH3 expression correlates with poor prognosis in patients with cervical cancer. TTYH3 markedly reduced the apoptosis rate and promoted proliferation, migration, and invasion. Silencing of TTYH3 has been shown to have an inhibitory effect on cervical cancer progression. Moreover, TTYH3 enhanced EMT and activated Wnt/β-catenin signaling. Furthermore, TTYH3 knockdown inhibited the tumor growth in vivo. In conclusion, TTYH3 promoted cervical cancer progression by activating the Wnt/β-catenin signaling. HIGHLIGHTS: TTYH3 is upregulated in cervical cancer tissue and cells. TTYH3 promotes cervical cancer cell proliferation. TTYH3 inhibits cervical cancer cell apoptosis. TTYH3 induces cervical cancer cell migration and invasion. TTYH3 activates the Wnt signaling in cervical cancer cell. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is an extremely toxic metal, capable of severely damaging several organs, including the brain. Studies have shown that Cd disrupts intracellular free calcium ([Ca2+]i) homeostasis, leading to apoptosis in a variety of cells including primary murine neurons. Calcium is a ubiquitous intracellular ion which acts as a signaling mediator in numerous cellular processes including cell proliferation, differentiation, and survival/death. However, little is known about the role of calcium signaling in Cd-induced apoptosis in neuronal cells. Thus we investigated the role of calcium signaling in Cd-induced apoptosis in primary rat cerebral cortical neurons. Consistent with known toxic properties of Cd, exposure of cerebral cortical neurons to Cd caused morphological changes indicative of apoptosis and cell death. It also induced elevation of [Ca2+]i and inhibition of Na+/K+-ATPase and Ca2+/Mg2+-ATPase activities. This Cd-induced elevation of [Ca2+]i was suppressed by an IP3R inhibitor, 2-APB, suggesting that ER-regulated Ca2+ is involved. In addition, we observed elevation of reactive oxygen species (ROS) levels, dysfunction of cytochrome oxidase subunits (COX-I/II/III), depletion of mitochondrial membrane potential (ΔΨm), and cleavage of caspase-9, caspase-3 and poly (ADP-ribose) polymerase (PARP) during Cd exposure. Z-VAD-fmk, a pan caspase inhibitor, partially prevented Cd-induced apoptosis and cell death. Interestingly, apoptosis, cell death and these cellular events induced by Cd were blocked by BAPTA-AM, a specific intracellular Ca2+ chelator. Furthermore, western blot analysis revealed an up-regulated expression of Bcl-2 and down-regulated expression of Bax. However, these were not blocked by BAPTA-AM. Thus Cd toxicity is in part due to its disruption of intracellular Ca2+ homeostasis, by compromising ATPases activities and ER-regulated Ca2+, and this elevation in Ca2+ triggers the activation of the Ca2+-mitochondria apoptotic signaling pathway. This study clarifies the signaling events underlying Cd neurotoxicity, and suggests that regulation of Cd-disrupted [Ca2+]i homeostasis may be a new strategy for prevention of Cd-induced neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Conclusion: Fas ligand (FasL) gene therapy may provide a new efficient therapeutic model for head and neck squamous cell cancer (HNSCC). Acid ceramidase (AC) may not play an important role in the sensitivity of HNSCC cell lines to Fas-induced apoptosis. Objectives: The aims of this study were to investigate the efficacy of FasL gene therapy for HNSCC in vitro and to determine whether the expression of AC in different kinds of HNSCC cell lines is related to the sensitivity of HNSCC cell lines to Fas-mediated apoptotic induction. Methods: Three HNSCC cell lines (Hep-2, MMSI, and SCCVII) were transfected with pEGFP-FasL, a plasmid containing a modified human FasL gene fused to enhanced green fluorescent protein (GFP). pEGFP-C1, a plasmid containing the GFP gene alone, was used as a control. Cell death was observed by fluorescence imaging and quantified using a tetrazolium-based (MTS) assay. SCCVII cells were analyzed by flow cytometry to determine the presence of apoptotic induction. Hep-2 and MMSI cells were evaluated by quantitative real-time PCR to evaluate the expression of AC. Results: Transfection of pEGFP-FasL plasmid was shown to be able to induce cell death, the sensitivity of Fas-mediated apoptosis in HNSCC was different, and the level of AC did not correlate with the sensitivity of HNSCC cells to Fas-induced apoptosis. [ABSTRACT FROM AUTHOR]

Bullacta exarata has been consumed in Asia, not only as a part of the normal diet, but also as a traditional Chinese medicine with liver- and kidney-benefitting functions. Several scientific investigations involving extraction of biomolecules from this mollusk and pharmacological studies on their biological activities have been carried out. However, little is known regarding the antitumor properties of polysaccharides from B. exarata, hence the polysaccharides from B. exarata have been investigated here. One polysaccharide conjugate BEPS-IA was isolated and purified from B. exarata. It mainly consisted of mannose and glucose in a molar ratio of 1:2, with an average molecular weight of 127 kDa. Thirteen general amino acids were identified to be components of the protein-bound polysaccharide. Methylation and NMR studies revealed that BEPS-IA is a heteropolysaccharide consisting of 1,4-linked-α-D-Glc, 1,6-linked-α-D-Man, 1,3,6-linked-α-D-Man, and 1-linked-α-D-Man residue, in a molar ratio of 6:1:1:1. In order to test the antitumor activity of BEPS-IA, we investigated its effect against the growth of human hepatocellular carcinoma cells HepG2 in vitro. The result showed that BEPS-IA dose-dependently exhibited an effective HepG2 cells growth inhibition with an IC50 of 112.4 μg/mL. Flow cytometry analysis showed that BEPS-IA increased the populations of both apoptotic sub-G1 and G1 phase. The result obtained from TUNEL assay corroborated apoptosis which was shown in flow cytometry. Western blot analysis suggested that BEPS-IA induced apoptosis and growth inhibition were associated with up-regulation of p53, p21 and Bax, down-regulation of Bcl-2. These findings suggest that BEPS-IA may serve as a potential novel dietary agent for hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]

Anti-apoptotic Bcl-2 family proteins, in particular, Mcl-1, are known to play a critical role in resistance of human melanoma cells to induction of apoptosis by endoplasmic reticulum stress and other agents. The present study examined whether the BH3 mimetics, Obatoclax and ABT-737, which inhibit multiple anti-apoptotic Bcl-2 family proteins, would overcome resistance to apoptosis. We report that both agents induced a strong unfolded protein response (UPR) and that RNAi knockdown of UPR signalling proteins ATF6, IRE1α and XBP-1 inhibited Mcl-1 upregulation and increased sensitivity to the agents. These results demonstrate that inhibition of anti-apoptotic Bcl-2 proteins by Obatoclax and ABT-737 appears to elicit a protective feedback response in melanoma cells, by upregulation of Mcl-1 via induction of the UPR. We also report that Obatoclax, but not ABT-737, strongly induces autophagy, which appears to play a role in determining melanoma sensitivity to the agents. [ABSTRACT FROM AUTHOR]

Endometriosis (EMs) is characterized by inflammatory lesions, dysmenorrhea, infertility, and chronic pelvic pain. Single-target medications often fail to provide systemic therapeutic results owing to the complex mechanism underlying endometriosis. Although traditional Chinese medicines—such as Juan-Tong-Yin (JTY)—have shown promising results, their mechanisms of action remain largely unknown. To elucidate the therapeutic mechanism of JTY in EMs, focusing on endoplasmic reticulum (ER) stress-induced autophagy. The major components of JTY were detected using high-performance liquid chromatography–mass spectrometry (HPLC–MS). The potential mechanism of JTY in EMs treatment was predicted using network pharmacological analysis. Finally, the pathogenesis of EMs was validated in a clinical case-control study and the molecular mechanism of JTY was validated in vitro using endometrial stromal cells (ESCs). In total, 241 compounds were analyzed and identified from JTY using UPLC–MS. Network pharmacology revealed 288 targets between the JTY components and EMs. Results of the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses indicated that regulating autophagy, migration, apoptosis, and inflammation were the key mechanisms of JTY in treating EMs. Meanwhile, we found that protein kinase R-like endoplasmic reticulum kinase (PERK), Beclin-1, and microtubule-associated protein light chain 3 B (LC3B) expressions were lower in endometria of patients with EMs than in those with normal eutopic endometria (p < 0.05). Additionally, during in vitro experiments, treatment with 20% JTY-containing serum significantly suppressed ESC proliferation, achieving optimal effects after 48 h. Electron microscopy revealed significantly increased autophagy flux in the JTY group compared with the control group. Moreover, JTY treatment significantly reduced the migratory and invasive abilities of ESCs and upregulated protein expression of PERK, eukaryotic initiation factor 2α (eIF2α)/phospho-eukaryotic initiation factor 2α (p-eIF2α), activating Transcription Factor-4 (ATF4), Beclin-1, and LC3BII/I, while subsequently downregulating NOD-like receptor thermal protein domain associated protein 3 (NLRP3) and interleukin 18 (IL-18) expression. However, administration of GSK2656157—a highly selective PERK inhibitor—reversed these changes. JTY ameliorates EMs by activating PERK associated with unfolded protein reaction, enhancing cell ER stress and autophagy, improving the inflammatory microenvironment, and decreasing the migration and invasion of ESCs. [Display omitted] • We examined the therapeutic mechanism of Juan-Tong-Yin in endometriosis. • Juan-Tong-Yin suppressed endometrial cell proliferation. • Juan-Tong-Yin increased autophagy in endometrial stromal cells. • Juan-Tong-Yin ameliorates endometriosis by activating the unfolded protein reaction triggered endoplasmic reticulum stress. [ABSTRACT FROM AUTHOR]

Background: This study aimed to investigate the neuroprotective function of a synthesized glucocorticoid‐induced leucine zipper peptide (GILZ‐p) in a light‐induced retinal degeneration model. Methods: The GILZ98‐134 peptide was synthesized and injected intravitreally into Sprague Dawley rats. Retinal injury was then induced in the rats by exposing their eyes to constant white light (5000 lux) for 24 h. The activation of retinal caspases‐9/3 and the release of cytochrome c from the mitochondria to the cytosol were measured at 1, 3, 5 and 7 d after light injury. Photoreceptor apoptosis was evaluated with terminal‐deoxynucleotidyl‐transferase‐mediated deoxyuridine triphosphate‐biotin nick end labelling (TUNEL) staining at 3 d after injury. Haematoxylin and eosin staining and electroretinography were used to observe the changes in the retinal morphology and function, respectively, at 7 and 14 d after light injury. Results: The intravitreally injected synthesized GILZ‐p successfully penetrated to the retina and significantly inhibited the activation of retinal caspase‐3 and caspase‐9 at 1, 3, 5 and 7 d after light injury, and reduced the number of TUNEL‐positive photoreceptors at 3 d after light injury. GILZ‐p pre‐treatment also alleviated cytochrome c release and rescued mitochondria‐mediated apoptosis after injury. Simultaneously, GILZ‐p pre‐treatment also mitigated the light‐induced thinning of the outer nuclear layer and the loss of retinal function at 7 and 14 d after light injury, respectively. Conclusions: The synthesized GILZ‐p prevented light‐induced photoreceptor apoptosis and protected retinal function from degeneration, and is therefore a potential therapeutic option for degenerative retinal diseases. [ABSTRACT FROM AUTHOR]

Chemoresistance remains a formidable hurdle against cancer therapy. Seeking for novel therapy strategies is an urgent need for those who no longer benefit from chemotherapy. Chemoresistance is usually associated with the dysfunction of intrinsic apoptosis. Targeting extrinsic apoptosis via TRAIL signaling and the death receptors could be a potential solution to treat chemoresistant cancer. A highly biocompatible nano system for codelivery of the TRAIL DNA and the death receptor sensitizer monensin was developed, in which low-molecular-weight PEI (LMW-PEI) was crosslinked by the sulfhydryl cyclodextrin via disulfide bonds, and then bound with DNA, thus forming the bioreducible polyplex cores. In addition, the cyclodextrin also functioned as a carrier for the hydrophobic monensin via host-guest inclusion. Poly-γ-glutamic acid (γ-PGA) was used to modify the polyplex core via charge interaction. The γ-PGA corona can specifically bind with the tumor-associated gamma-glutamyl transpeptidase (GGT) overexpressed on the tumor cells, and achieve tumor-targeting delivery. Moreover, the tumor-homing peptide RGD-modified γ-PGA was also prepared as the surface coating materials for further improving gene delivery efficiency. This gene delivery system was characterized by the dual ligand-targeting, dual stimuli-responsive features. The ligands of RGD and γ-PGA can target the tumor-associated receptors (i.e., integrin and GGT). The conformation of γ-PGA is pH-sensitive, and the tumor acidic micro environments could trigger the detachment of surface-coating γ-PGA. The disulfide crosslinking LMW-PEI is redox-sensitive, and its fast disassembling in the tumor cells could favor the efficient gene delivery. The anti-tumor efficacy was demonstrated both in vitro and in vivo. Moreover, MYC-mediated synthetic lethality could be an important mechanism for overcoming the drug resistance. An important finding of our studies is the demonstration of the in vivo treatment efficacy of TRAIL/monensin, thus providing a potential novel therapeutic strategy for overcoming drug-resistant cancer. [ABSTRACT FROM AUTHOR]

Background Recent evidence suggests that aberrant activation of Hedgehog (Hh) signaling by Gli transcription factors is characteristic of a variety of aggressive human carcinomas including gastric cancer. Speckle-type POZ protein, SPOP, is an E3 ubiquitin ligase adaptor, and it is found to inhibit oncogenic signaling. However, the molecular mechanisms are largely unknown. Methods In this study, we characterized the expression of SPOP in 88 pairs of gastric cancer tissues and adjacent tissues by immunohistochemical staining and Western blotting. The relationship between SPOP expression and clinical pathologic factors was analyzed. Transfected gastric cancer cell lines were used in cell viability, wound healing and colony formation assays. The interaction of SPOP with Gli2 and other related apoptotic proteins was assessed by immunoprecipitation, Western blotting, real-time PCR and dual luciferase reporter assays. Intracellular interaction of SPOP and Gli2 was visualized by immunofluorescent staining in gastric cancer cells. Results Immunohistochemical staining of SPOP can be detected in gastric cancer tissues but much less than adjacent gastric tissues (P < 0.01). High SPOP expression is negatively correlated with lymph node metastasis, poor histological differentiation, and tumor malignancy according to TNM staging. In vitro experiments revealed that over-expression of SPOP prevented tumor cells from proliferation, migration and colony formation in gastric cancer cell lines. Likewise, repression of SPOP promoted cell viability, migration, proliferation, and attenuated apoptosis. Mechanistic studies revealed that increasing SPOP accelerated Gli2 degradation but regardless of Gli2 synthesis. Furthermore, cytoplasmic Gli2 decreased markedly along with the abundant expression of SPOP in MKN45 cells. Conclusions Our findings indicate that SPOP plays critical roles in suppressing gastric tumorigenesis through inhibiting Hh/Gli2 signaling pathway. It may provide an alternative strategy for developing therapeutic agents of gastric cancer in future. [ABSTRACT FROM AUTHOR]

Objectives Vitexin-2″- O-rhamnoside ( VOR) and vitexin-4″- O-glucoside ( VOG) are the two main flavonoid glycosides of the leaves of C ratagus pinnatifida Bge. var. major N. E. Br. that has been widely used for the treatment of cardiovascular system diseases. In this study, we simultaneously investigated the influence of VOR and VOG on human adipose-derived stem cells (h ADSCs) injury induced by hydrogen peroxide ( H2O2) to further characterize their anti-oxidative and anti-apoptotic activity. Methods h ADSCs were isolated, cultured in vitro and pretreated with 62.5 μ m VOR or 120 μ m VOG for 24 h and then exposed to 500 μ m H2O2 for an additional 4 h. Key findings Pretreatment of h ADSCs with VOR and VOG was demonstrated to significantly ameliorate the toxicity and apoptosis effects, such as morphological distortion, nuclear condensation, decreased intracellular caspase-3 activity and percentage of cells in apoptosis/necrosis by using morphological assay, immunocytochemistry and flow cytometric evaluation. In addition, VOR and VOG caused no cytotoxic effect on hADSCs at concentrations up to 250 and 480 μ m, respectively. Conclusions Our results indicated that both VOR and VOG contribute to the protection against H2O2-mediated oxidative stress damage and could be safely used for a wide range of concentrations. [ABSTRACT FROM AUTHOR]

The activation of caspase-3 is an important hallmark in Parkinson’s disease. It could induce neuron death by apoptosis and microglia activation by inflammation. As a result, inhibition the activation of caspase-3 would exert synergistic dual effect in brain in order to prevent the progress of Parkinson’s disease. Silencing caspase-3 genes by RNA interference could inhibit the activation of caspase-3. We developed a brain-targeted gene delivery system based on non-viral gene vector, dendrigraft poly-L-lysines. A rabies virus glycoprotein peptide with 29 amino-acid linked to dendrigraft poly-L-lysines could render gene vectors the ability to get across the blood brain barrier by specific receptor mediated transcytosis. The resultant brain-targeted vector was complexed with caspase-3 short hairpin RNA coding plasmid DNA, yielding nanoparticles. In vivo imaging analysis indicated the targeted nanoparticles could accumulate in brain more efficiently than non-targeted ones. A multiple dosing regimen by weekly intravenous administration of the nanoparticles could reduce activated casapse-3 levels, significantly improve locomotor activity and rescue dopaminergic neuronal loss and in Parkinson’s disease rats’ brain. These results indicated the rabies virus glycoprotein peptide modified brain-targeted nanoparticles were promising gene delivery system for RNA interference to achieve anti-apoptotic and anti-inflammation synergistic therapeutic effects by down-regulation the expression and activation of caspase-3. [ABSTRACT FROM AUTHOR]

Abstract: TNF-related apoptosis-inducing ligand (TRAIL) appears to be a promising anticancer agent as it specifically kills a wide variety of cancer cells. However, resistance of subpopulations of cancer cells to TRAIL-induced cell death remains a major obstacle for successful treatment of cancer using TRAIL-based therapy. In this report we show that the hexokinase inhibitor 2-deoxy-d-glucose (2-DG) efficiently enhances TRAIL-induced apoptosis through downregulation of receptor-interacting protein kinase 1 (RIP1) in breast cancer cells. Although 2-DG alone did not kill breast cancer cells, it sensitized the cells to TRAIL-induced cell death. This could be efficiently inhibited by blockage of the caspase cascade, suggesting 2-DG augments TRAIL-mediated apoptotic signaling. Indeed, treatment with 2-DG resulted in upregulation of TRAIL receptor 2 (TRAIL-R2), downregulation of cIAP1 and XIAP, and reduction in RIP1. The latter appeared to play an important role in regulating sensitivity of breast cancer cells to TRAIL, in that knockdown of RIP1 recapitulated, at least in part, the effect of 2-DG on TRAIL-induced apoptosis. Taken together, these results indicate that 2-DG enhances TRAIL-induced apoptosis in breast cancer cells by multiple mechanisms including suppression of RIP1, and highlight the potential therapeutic benefit of combinations of 2-DG and TRAIL in the treatment of breast cancer. [Copyright &y& Elsevier]

Emerging evidence has pointed to biological roles of melanoma-associated antigens (MAGEs) in cancer development, progression and resistance to treatment. However, the mechanisms involved remain to be fully elucidated. In this report, we show that one of the MAGE proteins, MAGE-D2, suppresses the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) death receptor 2 (TRAIL-R2) and plays an important role in protecting melanoma cells from apoptosis induced by TRAIL. MAGE-D2 was commonly expressed at increased levels in melanoma cells compared with melanocytes. Although its inhibition by small interfering RNA (siRNA) did not cause cell death, it rendered melanoma cells more sensitive to TRAIL-induced apoptosis. This was associated with enhanced formation of TRAIL death-inducing signaling complex and up-regulation of TRAIL-R2, and was blocked by a recombinant TRAIL-R2/Fc chimeric protein or siRNA knockdown of TRAIL-R2. Regulation of TRAIL-R2 by MAGE-D2 appeared to be mediated by p53, in that knockdown MAGE-D2 did not up-regulate TRAIL-R2 in p53-null or mutant p53 melanoma cells. In addition, inhibition of MAGE-D2 did not result in up-regulation of TRAIL-R2 in wild-type p53 cell lines with p53 inhibited by short hairpin RNA. Indeed, knockdown of MAGE-D2 led to up-regulation of p53 due to a transcriptional increase. The regulatory effect of MAGE-D2 on TRAIL-R2 expression and TRAIL-induced apoptosis was recapitulated in studies on fresh melanoma isolates. Taken together, these results identify the expression of MAGE-D2 as an important mechanism that inhibit TRAIL-induced apoptosis and suggest that targeting MAGE-D2 may be a useful strategy in improving the therapeutic efficacy of TRAIL in melanoma. [ABSTRACT FROM PUBLISHER]

Abstract: Gene therapy offers a promising cure of brain glioma and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is able to induce cell apoptosis of glioma selectively without affecting the normal cells. In this study, the nanoscopic high-branching dendrimer, polyamidoamine (PAMAM), was selected as the principal vector. Angiopep-2, which can target to the low-density lipoprotein receptor-related protein-1 (LRP1) expressed on BCECs and glial cells, was exploited as the targeting ligand to conjugate PAMAM via bifunctional polyethyleneglycol (PEG) and then complexed with the DNA, designated as PAMAM-PEG-Angiopep/DNA nanoparticles (NPs). The cellular uptake mechanism explored in glial cells showed that the DNA of PAMAM-PEG-Angiopep/DNA NPs entered into the nuclei through the endosome/lysosome pathway. The in vivo biodistribution of PAMAM-PEG-Angiopep/DNA NPs in the brain especially the tumor site was higher than that of PAMAM-PEG/DNA NPs and PAMAM/DNA NPs. Furthermore, the TUNEL analysis showed a more wide-extended apoptosis in the PAMAM-PEG-Angiopep/pORF-TRAIL NPs treated group, compared to other groups including commercial Temozolomide-treated one. The median survival time of PAMAM-PEG-Angiopep/pORF-TRAIL NPs and Temozolomide treated on brain tumor-bearing mice was 61 and 49 days respectively, significantly longer than that of other groups. Besides, the NPs suggested low cytotoxicity after in vitro transfection. Thus, the results showed that Angiopep-2 could be exploited as a specific ligand to cross the BBB and targeted to glial cells, and PAMAM-PEG-Angiopep/DNA NPs can be a potential non-viral delivery system for gene therapy of glial tumor. [Copyright &y& Elsevier]

Abstract: A combination cancer therapy was investigated via co-delivery of therapeutic gene encoding human tumor necrosis factor-related apoptosis-inducing ligand (pORF-hTRAIL) and doxorubicin (DOX) using a tumor-targeting carrier, peptide HAIYPRH (T7)-conjugated polyethylene glycol-modified polyamidoamine dendrimer (PAMAM-PEG-T7). T7, a transferrin receptor-specific peptide, was chosen as the ligand to target the co-delivery system to the tumor cells expressing transferrin receptors. The result of fluorescence scanning showed that about 375 DOX molecules were bound to one pORF-hTRAIL molecule. The co-delivery system was constructed based on the electrostatic interactions between pORF-hTRAIL–DOX complex and cationic PAMAM-PEG-T7. T7-modified co-delivery system showed higher efficiency in cellular uptake and gene expression than unmodified co-delivery system in human liver cancer Bel-7402 cells, and accumulated in tumor more efficiently in vivo. In comparison with single DOX or pORF-hTRAIL delivery system, co-delivery system induced apoptosis of tumor cells in vitro and inhibited tumor growth in vivo more efficiently. In mice bearing Bel-7402 xenografts, lower doses of co-delivery system (4 μg DOX/mouse, about 0.16 mg/kg) effectively inhibited tumor growth comparable to high doses (5 mg/kg) of free doxorubicin (77% versus 69%). These results suggested that T7-mediated co-delivery system of DOX and pORF-hTRAIL was a simply prepared, combined delivery platform which can significantly improve the anti-tumor effect. This co-delivery system might widen the therapeutic window and allow for the selective destruction of cancer cells. [ABSTRACT FROM AUTHOR]

We previously demonstrated that AKT2, a member of protein kinase B family, is activated by a number of growth factors via Ras and PI 3-kinase signaling pathways. Here, we report the frequent activation of AKT2 in human primary ovarian cancer and induction of apoptosis by inhibition of phosphoinositide-3-OH kinase (PI 3-kinase)/Akt pathway. In vitro AKT2 kinase assay analyses in 91 ovarian cancer specimens revealed elevated levels of AKT2 activity (>3-fold) in 33 cases (36.3%). The majority of tumors displaying activated AKT2 were high grade and stages III and IV. Immunostaining and Western blot analyses using a phospho-ser-473 Akt antibody that detects the activated form of AKT2 (AKT2 phosphorylated at serine-474) confirmed the frequent activation of AKT2 in ovarian cancer specimens. Phosphorylated AKT2 in tumor specimens localized to the cell membrane and cytoplasm but not the nucleus. To address the mechanism of AKT2 activation, we measured in vitro PI 3-kinase activity in 43 ovarian cancer specimens, including the 33 cases displaying elevated AKT2 activation. High levels of PI 3-kinase activity were observed in 20 cases, 15 of which also exhibited AKT2 activation. The remaining five cases displayed elevated AKT1 activation. Among the cases with elevated AKT2, but not PI 3-kinase activity (18 cases), three showed down-regulation of PTEN protein expression. Inhibition of PI 3-kinase/AKT2 by wortmannin or LY294002 induces apoptosis in ovarian cancer cells exhibiting activation of the PI 3-kinase/AKT2 pathway. These findings demonstrate for the first time that activation of AKT2 is a common occurrence in human ovarian cancer and that PI 3-kinase/Akt pathway may be an important target for ovarian cancer intervention. Oncogene (2000) 19, 2324–2330 [ABSTRACT FROM AUTHOR]