Targeting STAT3 enhances NDV-induced immunogenic cell death in prostate cancer cells.

Oncolytic Newcastle disease virus (NDV) induces immunogenic cell death (ICD), liberating danger-associated molecular patterns (DAMPs) that provokes defiance in neoplastic malignancy. The present study aims to investigate whether and how oncolytic NDV triggers ICD in prostate cancer cells. We show that NDV/FMW, an oncolytic NDV strain FMW, elicited the expression and release of several ICD markers, that is calreticulin (CRT), heat shock proteins (HSP70/90) and high-mobility group box 1 (HMGB1), in prostate cancer cells. Furthermore, pharmacological repression of apoptosis, necroptosis, autophagy or endoplasmic reticulum (ER) stress exerted diverse effects on the HMGB1 and HSP70/90 evacuation in NDV/FMW-infected prostate cancer cells. Moreover, ICD markers induced in prostate cancer cells upon NDV/FMW infection, were enhanced by either treatment with a STAT3 (signal transducer and activator of transcription 3) inhibitor or shRNA-mediated knockdown of STAT3. In nude mice bearing prostate cancer cell-derived tumours, the tumours injected with the supernatants of NDV/FMW-infected cells grew smaller than mock-treated tumours. These results indicate that oncolytic NDV provokes the expression of ICD makers in prostate cancer cells. Our data also suggest that a combination of inhibition of STAT3 with oncolytic NDV could boost NDV-based anti-tumour effects against prostate cancer.

miR-285-Yki/Mask double-negative feedback loop mediates blood-brain barrier integrity in Drosophila.

The Hippo signaling pathway is highly conserved from Drosophila to mammals and plays a central role in maintaining organ size and tissue homeostasis. The blood-brain barrier (BBB) physiologically isolates the brain from circulating blood or the hemolymph system, and its integrity is strictly maintained to perform sophisticated neuronal functions. Until now, the underlying mechanisms of subperineurial glia (SPG) growth and BBB maintenance during development are not clear. Here, we report an miR-285-Yorkie (Yki)/Multiple Ankyrin repeats Single KH domain (Mask) double-negative feedback loop that regulates SPG growth and BBB integrity. Flies with a loss of miR-285 have a defective BBB with increased SPG ploidy and disruptive septate junctions. Mechanistically, miR-285 directly targets the Yki cofactor Mask to suppress Yki activity and down-regulates the expression of its downstream target cyclin E, a key regulator of cell cycle. Disturbance of cyclin E expression in SPG causes abnormal endoreplication, which leads to aberrant DNA ploidy and defective septate junctions. Moreover, the expression of miR-285 is increased by knockdown of yki or mask and is decreased with yki overexpression, thus forming a double-negative feedback loop. This regulatory loop is crucial for sustaining an appropriate Yki/Mask activity and cyclin E level to maintain SPG ploidy and BBB integrity. Perturbation of this signaling loop, either by dysregulated miR-285 expression or Yki activity, causes irregular SPG ploidy and BBB disruption. Furthermore, ectopic expression of miR-285 promotes canonical Hippo pathway-mediated apoptosis independent of the p53 or JNK pathway. Collectively, these results reveal an exquisite regulatory mechanism for BBB maintenance through an miR-285-Yki/Mask regulatory circuit.

Sirtuin1 activator SRT2183 suppresses glioma cell growth involving activation of endoplasmic reticulum stress pathway.

BACKGROUND: Glioblastoma (GBM) is an extremely deadly form of brain cancer with limited treatment options and thus novel therapeutic modalities are necessary. Histone deacetylase inhibitors (HDACi) have demonstrated clinical and preclinical activities against GBM. (Silent mating type information regulation 2 homolog, Sirt1) abbreviated as Sirtuin 1, has been implicated in GBM. We explored the activity of the Sirt1 activator SRT2183 in glioma cell lines in terms of biological response. METHODS: The effects of SRT2183 on glioma cell growth and neurosphere survival were evaluated in vitro using the CCK-8, clonogenic and neurosphere assays, respectively. Glioma cell cycle arrest and apoptosis were determined by flow cytometry. SRT2183-induced autophagy was investigated by detection of GFP-microtubule-associated protein 1 light chain 3 (GFP-LC3) puncta, conversion of the nonlipidated form of LC3 (LC3-I) to the phosphatidylethanolamine-conjugated form (LC3-II). Acetylation of STAT3 and NF-κB in SRT2183-treated glioma cells was examined using immunoprecipitation. The expression levels of anti-apoptotic proteins were assayed by immunoblotting. RESULTS: SRT2183 suppressed glioma cell growth and destroyed neurospheres in vitro. Furthermore, SRT2183 induced glioma cell cycle arrest and apoptosis, accompanying by upregulation of the pro-apoptotic Bim and downregulation of Bcl-2 and Bcl-xL. Notably, ER stress was triggered in glioma cells upon exposure to SRT2183 while the pre-exposure to 4-PBA, an ER stress inhibitor, significantly antagonized SRT2183-mediated growth inhibition in glioma cells. In addition, SRT2183 induced autophagy in glioma cells and pharmacological modulation of autophagy appeared not to affect SRT2183-inhibited cell growth. Of interest, the acetylation and phosphorylation of p65 NF-κB and STAT3 in glioma cells were differentially affected by SRT2183. CONCLUSIONS: Our data suggest the ER stress pathway is involved in SRT2183-mediated growth inhibition in glioma. Further investigation in vivo is needed to consolidate the data.

Recombinant oncolytic Newcastle disease virus displays antitumor activities in anaplastic thyroid cancer cells.

BACKGROUND: Anaplastic thyroid cancer (ATC) is one of the most aggressive of all solid tumors for which no effective therapies are currently available. Oncolytic Newcastle disease virus (NDV) has shown the potential to induce oncolytic cell death in a variety of cancer cells of diverse origins. However, whether oncolytic NDV displays antitumor effects in ATC remains to be investigated. We have previously shown that the oncolytic NDV strain FMW (NDV/FMW) induces oncolytic cell death in several cancer types. In the present study, we investigated the oncolytic effects of NDV/FMW in ATC. METHODS: In this study, a recombinant NDV expressing green fluorescent protein (GFP) was generated using an NDV reverse genetics system. The resulting virus was named after rFMW/GFP and the GFP expression in infected cells was demonstrated by direct fluorescence and immunoblotting. Viral replication was evaluated by end-point dilution assay in DF-1 cell lines. Oncolytic effects were examined by biochemical and morphological experiments in cultural ATC cells and in mouse models. RESULTS: rFMW/GFP replicated robustly in ATC cells as did its parent virus (NDV/FMW) while the expression of GFP protein was detected in lungs and spleen of mice intravenously injected with rFMW/GFP. We further showed that rFMW/GFP infection substantially increased early and late apoptosis in the ATC cell lines, THJ-16 T and THJ-29 T and increased caspase-3 processing and Poly (ADP-ribose) polymerase (PARP) cleavage in ATC cells as assessed by immunoblotting. In addition, rFMW/GFP induced lyses of spheroids derived from ATC cells in three-dimensional (3D) cultures. We further demonstrated that rFMW/GFP infection resulted in the activation of p38 MAPK signaling, but not Erk1/2 or JNK, in THJ-16 T and THJ-29 T cells. Notably, inhibition of p38 MAPK activity by SB203580 decreased rFMW/GFP-induced cleavage of caspase-3 and PARP in THJ-16 T and THJ-29 T cells. Finally, both rFMW/GFP and its parent virus inhibited tumor growth in mice bearing THJ-16 T derived tumors. CONCLUSION: Taken together, these data indicate that both the recombinant reporter virus rFMW/GFP and its parent virus NDV/FMW, display oncolytic activities in ATC cells in vitro and in vivo and suggest that oncolytic NDV may have potential as a novel therapeutic strategy for ATC.

E2F transcription factor 1 regulates cellular and organismal senescence by inhibiting Forkhead box O transcription factors.

E2F1 and FOXO3 are two transcription factors that have been shown to participate in cellular senescence. Previous report reveals that E2F1 enhanced cellular senescence in human fibroblast cells, while FOXO transcription factors play against senescence by regulation reactive oxygen species scavenging proteins. However, their functional interplay has been unclear. Here we use E2F1 knock-out murine Embryonic fibroblasts (MEFs), knockdown RNAi constructs, and ectopic expression of E2F1 to show that it functions by negatively regulating FOXO3. E2F1 attenuates FOXO3-mediated expression of MnSOD and Catalase without affecting FOXO3 protein stability, subcellular localization, or phosphorylation by Akt. We mapped the interaction between E2F1 and FOXO3 to a region including the DNA binding domain of E2F1 and the C-terminal transcription-activation domain of FOXO3. We propose that E2F1 inhibits FOXO3-dependent transcription by directly binding FOXO3 in the nucleus and preventing activation of its target genes. Moreover, knockdown of the Caenorhabditis elegans E2F1 ortholog efl-1 significantly extends lifespan in a manner that requires the activity of the C. elegans FOXO gene daf-16. We conclude that there is an evolutionarily conserved signaling connection between E2F1 and FOXO3, which regulates cellular senescence and aging by regulating the activity of FOXO3. We speculate that drugs and/or therapies that inhibit this physical interaction might be good candidates for reducing cellular senescence and increasing longevity.

Autophagy benefits the replication of Newcastle disease virus in chicken cells and tissues.

Newcastle disease virus (NDV) is an important avian pathogen. We previously reported that NDV triggers autophagy in U251 glioma cells, resulting in enhanced virus replication. In this study, we investigated whether NDV triggers autophagy in chicken cells and tissues to enhance virus replication. We demonstrated that NDV infection induced steady-state autophagy in chicken-derived DF-1 cells and in primary chicken embryo fibroblast (CEF) cells, evident through increased double- or single-membrane vesicles, the accumulation of green fluorescent protein (GFP)-LC3 dots, and the conversion of LC3-I to LC3-II. In addition, we measured autophagic flux by monitoring p62/SQSTM1 degradation, LC3-II turnover, and GFP-LC3 lysosomal delivery and proteolysis, to confirm that NDV infection induced the complete autophagic process. Inhibition of autophagy by pharmacological inhibitors and RNA interference reduced virus replication, indicating an important role for autophagy in NDV infection. Furthermore, we conducted in vivo experiments and observed the conversion of LC3-I to LC3-II in heart, liver, spleen, lung, and kidney of NDV-infected chickens. Regulation of the induction of autophagy with wortmannin, chloroquine, or starvation treatment affects NDV production and pathogenesis in tissues of both lung and intestine; however, treatment with rapamycin, an autophagy inducer of mammalian cells, showed no detectable changes in chicken cells and tissues. Moreover, administration of the autophagy inhibitor wortmannin increased the survival rate of NDV-infected chickens. Our studies provide strong evidence that NDV infection induces autophagy which benefits NDV replication in chicken cells and tissues.

Gamabufotalin, a bufadienolide compound from toad venom, suppresses COX-2 expression through targeting IKKß/NF-κB signaling pathway in lung cancer cells.

BACKGROUND: Gamabufotalin (CS-6), a major bufadienolide of Chansu, has been used for cancer therapy due to its desirable metabolic stability and less adverse effect. However, the underlying mechanism of CS-6 involved in anti-tumor activity remains poorly understood. METHODS: The biological functions of gamabufotalin (CS-6) were investigated by migration, colony formation and apoptosis assays in NSCLC cells. The nuclear localization and interaction between transcriptional co-activator p300 and NF-κB p50/p65 and their binding to COX-2 promoter were analyzed after treatment with CS-6. Molecular docking study was used to simulate the interaction of CS-6 with IKKß. The in vivo anti-tumor efficacy of CS-6 was also analyzed in xenografts nude mice. Western blot was used to detect the protein expression level. RESULTS: Gamabufotalin (CS-6) strongly suppressed COX-2 expression by inhibiting the phosphorylation of IKKß via targeting the ATP-binding site, thereby abrogating NF-κB binding and p300 recruitment to COX-2 promoter. In addition, CS-6 induced apoptosis by activating the cytochrome c and caspase-dependent apoptotic pathway. Moreover, CS-6 markedly down-regulated the protein levels of COX-2 and phosphorylated p65 NF-κB in tumor tissues of the xenograft mice, and inhibited tumor weight and size. CONCLUSIONS: Our study provides pharmacological evidence that CS-6 exhibits potential use in the treatment of COX-2-mediated diseases such as lung cancer.

Pharmacological modulation of autophagy enhances Newcastle disease virus-mediated oncolysis in drug-resistant lung cancer cells.

BACKGROUND: Oncolytic viruses represent a promising therapy against cancers with acquired drug resistance. However, low efficacy limits its clinical application. The objective of this study is to investigate whether pharmacologically modulating autophagy could enhance oncolytic Newcastle disease virus (NDV) strain NDV/FMW virotherapy of drug-resistant lung cancer cells. METHODS: The effect of NDV/FMW infection on autophagy machinery in A549 lung cancer cell lines resistant to cisplatin (A549/DDP) or paclitaxel (A549/PTX) was investigated by detection of GFP-microtubule-associated protein 1 light chain 3 (GFP-LC3) puncta, formation of double-membrane vesicles and conversion of the nonlipidated form of LC3 (LC3-I) to the phosphatidylethanolamine-conjugated form (LC3-II). The effects of autophagy inhibitor chloroquine (CQ) and autophagy inducer rapamycin on NDV/FMW-mediated antitumor activity were evaluated both in culture cells and in mice bearing drug-resistant lung cancer cells. RESULTS: We show that NDV/FMW triggers autophagy in A549/PTX cells via dampening the class I PI3K/Akt/mTOR/p70S6K pathway, which inhibits autophagy. On the contrary, NDV/FMW infection attenuates the autophagic process in A549/DDP cells through the activation of the negative regulatory pathway. Furthermore, combination with CQ or knockdown of ATG5 significantly enhances NDV/FMW-mediated antitumor effects on A549/DDP cells, while the oncolytic efficacy of NDV/FMW in A549/PTX cells is significantly improved by rapamycin. Interestingly, autophagy modulation does not increase virus progeny in these drug resistant cells. Importantly, CQ or rapamycin significantly potentiates NDV/FMW oncolytic activity in mice bearing A549/DDP or A549/PTX cells respectively. CONCLUSIONS: These results demonstrate that combination treatment with autophagy modulators is an effective strategy to augment the therapeutic activity of NDV/FMW against drug-resistant lung cancers.

Osimertinib induces paraptosis and TRIP13 confers resistance in glioblastoma cells.

The efficacy of osimertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor, has been evaluated in glioblastoma (GBM) through preclinical and clinical trials. However, the underlying mechanism of osimertinib-induced GBM cell death and the underlying resistance mechanism to osimertinib remains unclear. Here, we demonstrate that Osimertinib induces paraptosis in GBM cells, as evidenced by the formation of cytoplasmic vacuoles, accumulation of ubiquitinated proteins, and upregulation of endoplasmic reticulum (ER) stress markers like CHOP. Additionally, neither apoptosis nor autophagy was involved in the osimertinib-induced cell death. RNAseq analysis revealed ER stress was the most significantly downregulated pathway upon exposure to osimertinib. Consistently, pharmacologically targeting the PERK-eIF2α axis impaired osimertinib-induced paraptosis. Notably, we show that the expression of thyroid receptor-interacting protein 13 (TRIP13), an AAA+ATPase, alleviated osimertinib-triggered paraptosis, thus conferring resistance. Intriguingly, MK-2206, an AKT inhibitor, downregulated TRIP13 levels and synergized with Osimertinib to suppress TRIP13-induced high GBM cell growth in vitro and in vivo. Together, our findings reveal a novel mechanism of action associated with the anti-GBM effects of osimertinib involving ER stress-regulated paraptosis. Furthermore, we identify a TRIP13-driven resistance mechanism against Osimertinib in GBM and offer a combination strategy using MK-2206 to overcome such resistance.

Interleukin-22 protects rat PC12 pheochromocytoma cells from serum deprivation-induced cell death.

Interleukin-22 (IL-22), an IL-10 family cytokine, mediates the crosstalk between leukocytes and epithelial cells. Previous studies reported that IL-22 expresses in mouse brain, and the rat PC12 cells are responsive to IL-22 stimulation. However, the biological roles of IL-22 in neuronal cells remain largely unknown. We show here that IL-22 activates Stat3, p38 mitogen-activated protein kinases (MAPK), and Akt pathways and inhibits Erk/MAPK pathway in naïve PC12 cells. We further demonstrate that IL-22 protects naïve PC12 cells from serum starvation-induced cell death via the Jak1/Stat3 and Akt pathways. We also show that IL-22 has no effects on naïve PC12 cell proliferation and cannot protect naïve PC12 cells from 1-methyl-4-phenylpyridinium (MPP(+))-induced cytotoxicity. However, IL-22 exerts a dose-dependent protective effect on MPP(+)-induced neurodegeneration in nerve growth factor-differentiated PC12 cells. Overall, our data suggest that IL-22 might play a role in neurological processes. To our knowledge, this is the first report showing that IL-22 confers a neuroprotective function, which may provide a new therapeutic option for treatment of neurodegenerative diseases.

Participation of Gab1 and Gab2 in IL-22-mediated keratinocyte proliferation, migration, and differentiation.

Interleukin-22 (IL-22) is one of the key mediators of keratinocyte alterations in psoriasis. IL-22 inhibits keratinocyte differentiation and induces the migration of human keratinocytes. Grb2-associated binder 1 (Gab1) has been shown to mediate epidermal growth factor-induced epidermal growth and differentiation via interaction with the Src homology-2-containing protein-tyrosine phosphatase (Shp2). In this investigation, we explore the role of Gab1 and Gab2 in IL-22-mediated keratinocyte activities. We show that both Gab1 and Gab2 were tyrosine phosphorylated in IL-22-stimulated HaCaT cells and human primary epidermal keratinocytes and contributed to the activation of Extracellular signal regulated kinase 1/2 (Erk1/2) through interaction with Shp2. We further demonstrate that HaCaT cells infected with adenoviruses expressing Shp2-binding-defective Gab1/2 mutants exhibited decreased cell proliferation and migration, as well as increased differentiation. Moreover, similar results were observed in HaCaT cells infected with adenovirus-based small interfering RNAs targeting Gab1 and/or Gab2. Altogether, these data underscore the critical roles of Gab1 and Gab2 in IL-22-mediated HaCaT cell proliferation, migration, and differentiation.

Apoptin enhances the oncolytic properties of Newcastle disease virus.

OBJECTIVE: Naturally occurring strains of Newcastle disease virus (NDV) have demonstrated the potential to kill cancer cells in both preclinical and clinical studies. Previous studies showed that apoptin, the VP3 protein of chicken infectious anemia virus, is a p53-independent, Bcl-2-insensitive apoptotic protein with the ability to specifically induce apoptosis in transformed cells. In this study, we tested the hypothesis that apoptin enhances NDV-mediated tumor cell death. METHODS: Reverse genetics was used to engineer an oncolytic NDV strain, FMW, to express apoptin. The antitumor effects of the recombinant virus (rFMW/AP) were also evaluated in the tumor cell lines and tumor-bearing mice. RESULTS: Compared to the parental strain FMW, rFMW/AP was more potent in killing A459 and SMMC7721 tumor cells. Recombinant NDV also exhibited higher efficacy in suppressing tumor growth in mice bearing A549-induced tumors. Furthermore, rFMW/AP did not display apparent toxic effects in either normal cells or control mice. CONCLUSION: Our results suggest that the recombinant NDV expressing apoptin is a promising novel antitumor agent.

Avian reovirus triggers autophagy in primary chicken fibroblast cells and Vero cells to promote virus production.

Avian reovirus (ARV) is an important cause of disease in poultry. Although ARV is known to induce apoptosis in infected cells, the interaction between ARV and its target cells requires further elucidation. In this report, we show that the ARV isolate strain GX/2010/1 induces autophagy in both Vero and primary chicken embryonic fibroblast (CEF) cells based on the appearance of an increased number of double-membrane vesicles, the presence of GFP-microtubule-associated protein 1 light chain 3 (GFP-LC3) dot formation, and the elevated production of LC3II. We further demonstrate that the class I phosphoinositide 3-kinase (PI3K)/Akt/mTOR pathway contributes to autophagic induction by ARV infection. Moreover, treatment of ARV-infected cells with the autophagy inducer rapamycin increased viral yields, while inhibition of the autophagosomal pathway using chloroquine led to a decrease in virus production. Altogether, our studies strongly suggest that autophagy may play a critical role in determining viral yield during ARV infection.

Newcastle disease virus triggers autophagy in U251 glioma cells to enhance virus replication.

Newcastle disease virus (NDV) can replicate in tumor cells and induce apoptosis in late stages of infection. However, the interaction between NDV and cells in early stages of infection is not well understood. Here, we report that, shortly after infection, NDV triggers the formation of autophagosomes in U251 glioma cells, as demonstrated by an increased number of double-membrane vesicles, GFP-microtubule-associated protein 1 light chain 3 (GFP-LC3) a dot formations, and elevated production of LC3II. Moreover, modulation of NDV-induced autophagy by rapamycin, chloroquine or small interfering RNAs targeting the genes critical for autophagosome formation (Atg5 and Beclin-1) affects virus production, indicating that autophagy may be utilized by NDV to facilitate its own production. Furthermore, the class III phosphatidylinositol 3-kinase (PI3K)/Beclin-1 pathway plays a role in NDV-induced autophagy and virus production. Collectively, our data provide a unique example of a paramyxovirus that uses autophagy to enhance its production.

SUFU suppresses ferroptosis sensitivity in breast cancer cells via Hippo/YAP pathway.

Ferroptosis is a new kind of regulated cell death that is characterized by highly iron-dependent lipid peroxidation. Cancer cells differ in their sensitivity to ferroptosis. Here we showed that the Suppressor of fused homolog (SUFU), a critical component in Hedgehog signaling, regulates ferroptosis sensitivity of breast cancer cells. Ectopic SUFU expression suppressed, whereas depletion of SUFU enhanced the sensitivity of breast cancer cells to RSL3-triggered ferroptosis through deregulation of ACSL4. Moreover, SUFU depletion promoted the activation of Yes-associated protein (YAP), thereby increasing the expression of ACSL4. Mechanistically, SUFU is associated with LATS1. Deletion of a region comprising residues 174-385 in SUFU disrupted SUFU binding to LATS1, thus abrogating SUFU-mediated downregulation of the YAP-ACSL4 axis and sensitivity to ferroptosis. Noteworthy, we showed that vincristine downregulated SUFU, thus increasing breast cancer cell sensitivity to RSL3 in vitro and in vivo. Together, our findings uncover SUFU as a novel regulator in ferroptosis sensitivity.

Biphasic activation of PI3K/Akt and MAPK/Erk1/2 signaling pathways in bovine herpesvirus type 1 infection of MDBK cells.

Many viruses have been known to control key cellular signaling pathways to facilitate the virus infection. The possible involvement of signaling pathways in bovine herpesvirus type 1 (BoHV-1) infection is unknown. This study indicated that infection of MDBK cells with BoHV-1 induced an early-stage transient and a late-stage sustained activation of both phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen activated protein kinases/extracellular signal-regulated kinase 1/2 (MAPK/Erk1/2) signaling pathways. Analysis with the stimulation of UV-irradiated virus indicated that the virus binding and/or entry process was enough to trigger the early phase activations, while the late phase activations were viral protein expression dependent. Biphasic activation of both pathways was suppressed by the selective inhibitor, Ly294002 for PI3K and U0126 for MAPK kinase (MEK1/2), respectively. Furthermore, treatment of MDBK cells with Ly294002 caused a 1.5-log reduction in virus titer, while U0126 had little effect on the virus production. In addition, the inhibition effect of Ly294002 mainly occurred at the post-entry stage of the virus replication cycle. This revealed for the first time that BoHV-1 actively induced both PI3K/Akt and MAPK/Erk1/2 signaling pathways, and the activation of PI3K was important for fully efficient replication, especially for the post-entry stage.

Caspase- and p38-MAPK-dependent induction of apoptosis in A549 lung cancer cells by Newcastle disease virus.

Newcastle disease virus (NDV) has a potential oncolytic effect due to its ability to induce apoptosis in tumor cells. However, previous studies have indicated discrepancies regarding the apoptosis signaling pathways induced by NDV in tumor cells. Here, we show that NDV infection induces simultaneous activation of intrinsic and extrinsic death pathways in A549 human lung cancer cells. In contrast, endoplasmic reticulum (ER) stress is not activated in NDV-induced apoptosis. We demonstrate for the first time that mitogen-activated protein kinase (MAPK) pathways are activated in NDV-infected A549 cells, and p38 MAPK is involved in NDV-induced cell death. Together, our findings provide novel insights into the underlying mechanisms by which NDV induces apoptosis in tumor cells.

The kynurenine derivative 3-HAA sensitizes hepatocellular carcinoma to sorafenib by upregulating phosphatases.

Objectives: Sorafenib is the only FDA-approved first-line target drug for HCC patients. However, sorafenib merely confers 3-5 months of survival benefit with less than 30% of HCC patients sensitive to sorafenib therapy. Thus, it's necessary to develop a sensitizer for hepatocellular carcinoma (HCC) to sorafenib. Methods: The principal component analysis, gene ontology, and KEGG analysis are utilized following RNA-sequencing. The mass spectrometry analysis following immunoprecipitation is performed to discover the phosphatase targets. Most importantly, both the cell line-derived xenograft (CDX) and the patient-derived xenograft (PDX) mouse model are used to determine the effect of 3-HAA on sorafenib-resistant HCC in vivo. Results: In nude mice carrying HCC xenograft, tumor growth is inhibited by sorafenib or 3-HAA alone. When used in combination, the treatment particularly prevents the xenograft from growing. Combined treatment also suppresses the growth of sorafenib-resistant (≥30mg/kg) PDXs. In a set of mechanistic experiments, we find enhanced AKT activation and decreased apoptotic cells in de novo and acquired sorafenib-resistant HCC cells and tissues. 3-HAA decreases AKT phosphorylation and increases the apoptosis of HCC in both cultured cells and mouse xenografts by upregulation of phosphatases PPP1R15A/DUSP6. PPP1R15A/PPP1α directly reduces Akt phosphorylation while DUSP6 decreases Akt activity through inhibiting PDK1. The AKT activator abolishes 3-HAA inhibition of HCC growth in vitro and in mice. Conclusion: This study demonstrates that 3-HAA sensitizes HCC cells to sorafenib by upregulation of phosphatases, suggesting it as a promising molecule for HCC therapy.

Newcastle-disease-virus-induced ferroptosis through nutrient deprivation and ferritinophagy in tumor cells.

A number of new cell death processes have been discovered in recent years, including ferroptosis, which is characterized by the accumulation of lipid peroxidation products derived from iron metabolism. The evidence suggests that ferroptosis has a tumor-suppressor function. However, the mechanism by which ferroptosis mediates the response of tumor cells to oncolytic viruses remains poorly understood. The Newcastle disease virus (NDV) can selectively replicate in tumor cells. We show that NDV-induced ferroptosis acts through p53-SLC7A11-GPX4 pathway. Meanwhile, the levels of intracellular reactive oxygen species and lipid peroxides increased in tumor cells. Ferritinophagy was induced by NDV promotion of ferroptosis through the release of ferrous iron and an enhanced Fenton reaction. Collectively, these observations demonstrated that the NDV can kill tumor cells through ferroptosis. Our study provides novel insights into the mechanisms of NDV-induced ferroptosis and highlights the critical role of viruses in treating therapy-resistant cancers.