Targeting PARG induces tumor cell growth inhibition and antitumor immune response by reducing phosphorylated STAT3 in ovarian cancer.

BACKGROUND: Ovarian cancer is the most lethal gynecological malignancy, with limited treatment options after failure of standard therapies. Despite the potential of poly(ADP-ribose) polymerase inhibitors in treating DNA damage response (DDR)-deficient ovarian cancer, the development of resistance and immunosuppression limit their efficacy, necessitating alternative therapeutic strategies. Inhibitors of poly(ADP-ribose) glycohydrolase (PARG) represent a novel class of inhibitors that are currently being assessed in preclinical and clinical studies for cancer treatment. METHODS: By using a PARG small-molecule inhibitor, COH34, and a cell-penetrating antibody targeting the PARG's catalytic domain, we investigated the effects of PARG inhibition on signal transducer and activator of transcription 3 (STAT3) in OVCAR8, PEO1, and Brca1-null ID8 ovarian cancer cell lines, as well as in immune cells. We examined PARG inhibition-induced effects on STAT3 phosphorylation, nuclear localization, target gene expression, and antitumor immune responses in vitro, in patient-derived tumor organoids, and in an immunocompetent Brca1-null ID8 ovarian mouse tumor model that mirrors DDR-deficient human high-grade serous ovarian cancer. We also tested the effects of overexpressing a constitutively activated STAT3 mutant on COH34-induced tumor cell growth inhibition. RESULTS: Our findings show that PARG inhibition downregulates STAT3 activity through dephosphorylation in ovarian cancer cells. Importantly, overexpression of a constitutively activated STAT3 mutant in tumor cells attenuates PARG inhibitor-induced growth inhibition. Additionally, PARG inhibition reduces STAT3 phosphorylation in immune cells, leading to the activation of antitumor immune responses, shown in immune cells cocultured with ovarian cancer patient tumor-derived organoids and in immune-competent mice-bearing mouse ovarian tumors. CONCLUSIONS: We have identified a novel antitumor mechanism underlying PARG inhibition beyond its primary antitumor effects through blocking DDR in ovarian cancer. Furthermore, targeting PARG activates antitumor immune responses, thereby potentially increasing response rates to immunotherapy in patients with ovarian cancer.

Fluoxetine Inhibits STAT3-mediated Survival and Invasion of Osteosarcoma Cells.

BACKGROUND/AIM: Osteosarcoma (OS) is a common primary malignancy of bone in adolescents. Its highly metastatic characteristics can lead to treatment failure and poor prognosis. Although standard treatments, including surgery, radiotherapy, and chemotherapy, have progressed in the past decade, treatment options to overcome metastatic progression remain sparse. Fluoxetine, an anti-depressant, has been widely used in patients with cancer for their mental issues and was reported to possess antitumor potential. However, the effect of fluoxetine on OS remains unclear. MATERIALS AND METHODS: In this study, we used cell viability, invasion/migration transwell, wound-healing and aortic ring assays to identify the effects of fluoxetine on metastasis and progression in OS. RESULTS: Fluoxetine induced cytotoxicity in OS cells by activating both extrinsic/intrinsic apoptosis signaling pathways. Proliferation and anti-apoptosis-related factors such as cyclin D1 and X-linked inhibitor of apoptosis were suppressed by fluoxetine. Additionally, fluoxetine suppressed the invasive/migratory abilities of OS and inhibited the development of angiogenesis by reducing the phosphorylation of signal transducer and activator of transcription 3 (STAT3). Metastasis-associated factors, vascular endothelial growth factors, matrix metallopeptidase 2 and -9, were all reduced in OS cells by fluoxetine treatment. CONCLUSION: Fluoxetine not only induces cytotoxicity and apoptosis of OS cells, but also suppresses metastasis and angiogenesis by targeting STAT3.

Osteocalcin inhibits myocyte aging through promotion of starvation-induced autophagy via IL-6/STAT3 signaling.

This study aimed to investigate the effects and mechanisms of osteocalcin on autophagy in myoblasts, as well as its possible therapeutic effects in aging muscle. Starved murine myoblast C2C12 cells with or without interleukin (IL)-6 siRNA were treated with osteocalcin. Expression of the autophagy protein marker LC3, as well as IL-6 and phosphorylated STAT3 were detected by immunoblotting, immunofluorescence, or immunohistochemistry. Autophagosomes were observed with transmission electron microscopy. Levels of reactive oxygen species (ROS) were detected by flow cytometry. Fasted young mice were injected intraperitoneally with osteocalcin, with or without the JAK inhibitor CP-690550 to inhibit IL-6 signaling. Older mice were treated with osteocalcin and muscle mass, grip strength and muscle structure were assessed. The results revealed that compared to control and serum-starved cells, osteocalcin treatment significantly increased the relative expression of LC3-II/LC3-I protein, the numbers of autophagosomes, and levels of intracellular ROS. Osteocalcin injection in mice also resulted in increased relative LC3-II/LC3-I protein expression and autophagosome numbers. Osteocalcin treatment significantly increased the secretion of IL-6 in muscle cells and tissue, and activated STAT3 signaling. Moreover, knockdown of IL-6 or blocking IL-6 signaling inhibited the phosphorylation of STAT3, and further inhibited autophagy in starved myoblasts and fasting-treated murine muscle tissue. In addition, osteocalcin treatment significantly increased muscle mass and grip strength in both aged mice and aged fasting mice. In conclusion, the inhibition of osteocalcin on muscle cell aging is accompanied by the induction of IL-6-STAT3-dependent autophagy, indicating osteocalcin might be a promising therapeutic candidate for aging-related myopathies.

The synthesis of novel thioderivative chalcones and their influence on NF-κB, STAT3 and NRF2 signaling pathways in colorectal cancer cells.

This study aimed to synthesize new thioderivative chalcones and analyze their impact on the NF-κB, STAT3, EGFR and Nrf2 signaling pathways in colorectal cancer cells. Among the studied compounds, derivatives 4 and 5 decreased the activation of NF-κB and the expression of the target gene COX-2. In the case of STAT3, we observed the inhibition of activation of this signaling pathway after influencing derivative 4. Increased activation of the Nrf2 signaling pathway was demonstrated for derivatives 5 and 7 in DLD-1 and HCT116 cells. The results of this study indicated that new chalcone derivatives, especially compounds 4, 5, and-to some degree-7, possess potential applications in the prevention of colorectal cancer.

Design and optimization of cranberry extract loaded bile salt augmented liposomes for targeting of MCP-1/STAT3/VEGF signaling pathway in DMN-intoxicated liver in rats.

Cranberry extract (CBE) is a major source of the antioxidant polyphenolics but suffers from limited bioavailability. The goal of this research was to encapsulate the nutraceutical (CBE), into bile salt augmented liposomes (BSALs) as a promising oral delivery system to potentiate its hepatoprotective impact against dimethylnitrosamine (DMN) induced liver injury in rats. The inclusion of bile salt in the liposomal structure can enhance their stability within the gastrointestinal tract and promote CBE permeability. CBE loaded BSALs formulations were fabricated utilizing a (23) factorial design to explore the impact of phospholipid type (X1), phospholipid amount (X2), and sodium glycocholate (SGC) amount (X3) on BSALs properties, namely; entrapment efficiency percent, (EE%); vesicle size, (VS); polydispersity index; (PDI); zeta potential, (ZP); and release efficiency percent, (RE%). The optimum formulation (F1) exhibited spherical vesicles with EE% of 71.27 ± 0.32%, VS; 148.60 ± 6.46 nm, PDI; 0.38 ± 0.02, ZP; -18.27 ± 0.67 mV and RE%; 61.96 ± 1.07%. Compared to CBE solution, F1 had attenuated DMN-induced hepatic injury, as evidenced by the significant decrease in serum level of ALT, AST, ALP, MDA, and elevation of GSH level, as well as SOD and GPX activities. Furthermore, F1 exhibited an anti-inflammatory character by suppressing TNF-α, MCP-1, and IL-6, as well as downregulation of VEGF-C, STAT-3, and IFN-γ mRNA levels. This study verified that when CBE was integrated into BSALs, F1, its hepatoprotective effect was significantly potentiated to protect the liver against DMN-induced damage. Therefore, F1 could be deliberated as an antioxidant, antiproliferative, and antifibrotic therapy to slow down the progression of hepatic damage.

Inhibition of GP130/STAT3 and EMT by combined bazedoxifene and paclitaxel treatment in ovarian cancer.

The interleukin 6 (IL­6)/glycoprotein 130 (GP130)/signal transducer and activator of transcription 3 (STAT3) signalling pathway, with GP130 as an intermediate membrane receptor, is involved in the survival, metastasis, and resistance of ovarian cancer. Bazedoxifene, an FDA­approved drug, is an inhibitor of GP130 and a selective estrogen modulator (SERM). We studied the mechanism of the combination therapy of bazedoxifene and paclitaxel in inhibiting the IL­6­mediated GP130/STAT3 signaling pathway in ovarian cancer. Surface plasmon resonance (SPR) was used to assess the binding of bazedoxifene to GP130. Migration, invasion, and apoptosis of ovarian cancer cells were assessed using bazedoxifene and paclitaxel. In addition, we determined the effects of bazedoxifene and paclitaxel alone or in combination on the GP130/STAT3 pathway and epithelial­mesenchymal transition (EMT). The results revealed that the combination of bazedoxifene and paclitaxel suppressed cell viability, migration, and invasion in the ovarian cancer cells. In addition, the combination treatment increased apoptosis. Furthermore, bazedoxifene combined with paclitaxel inhibited the growth of ovarian cancer cells in a xenograft tumour model. This combination reduced STAT3 phosphorylation and suppressed gene expression and EMT. In conclusion, inhibition of GP130/STAT3 signalling and EMT via a combination of bazedoxifene and paclitaxel could be used as a therapeutic strategy by which to overcome ovarian cancer.

Sensitivity of eight types of ALK fusion variant to alectinib in ALK-transformed cells.

Tyrosine kinase inhibitors of anaplastic lymphoma kinase (ALK-TKIs) including alectinib have been the standard therapy against ALK fusion gene-positive non-small cell lung cancers (NSCLCs). Many ALK fusion variants have been identified in NSCLCs, and the predominant variants are echinoderm microtubule-associated protein-like 4-ALK (EML4-ALK) variant 1 (V1), V2 and V3a/b. However, there have been conflicting reports on the clinical responses of these variants to ALK-TKIs, and there are few reports on other less common ALK variants. To examine the influence of ALK variants on the efficacy of ALK-TKIs, we analyzed the sensitivity to alectinib of eight types of ALK variant: three major variants (V1, V2 and V3a) and five less common variants (V4; kinesin family member 5-ALK; kinesin light chain 1-ALK; striatin, calmodulin-binding protein-ALK; and tropomyosin-receptor kinase fused gene-ALK). Analysis was done by cell-free kinase assays using the recombinant proteins and by cell, growth assays using murine Ba/F3 cells expressing ALK variants. The kinase activity of each recombinant protein was significantly inhibited by alectinib. Intracellular ALK phosphorylation levels and its downstream signaling mediators, STAT3 and ERK, were suppressed by alectinib in each ALK variant-expressing Ba/F3 cell. Each cellular proliferation was markedly inhibited by alectinib treatment. There was no significant difference in the IC50 values between cells, with a <3.6-fold difference in responsiveness. In conclusion, these eight ALK variants had similar sensitivity to alectinib in vitro, indicating that it may not be possible to predict the response to alectinib just by determination of the ALK variant type in ALK fusion-positive NSCLCs.

Epac activation ameliorates tubulointerstitial inflammation in diabetic nephropathy.

Tubulointerstitial inflammation plays an important role in the progression of diabetic nephropathy (DN), and tubular epithelial cells (TECs) are crucial promoters of the inflammatory cascade. Exchange protein activated by cAMP (Epac) has been shown to suppress the angiotensin II (Ang-II)-induced release of inflammatory cytokines in tubular cells. However, the role of Epac in TEC-mediated tubulointerstitial inflammation in DN remains unknown. We found that administering the Epac agonist 8-pCPT-2'-O-Me-cAMP (8-O-cAMP) to db/db mice inhibited tubulointerstitial inflammation characterized by macrophage infiltration and increased inflammatory cytokine release and consequently alleviated tubulointerstitial fibrosis in the kidney. Furthermore, 8-O-cAMP administration restored CCAAT/enhancer binding protein ß (C/EBP-ß) expression and further upregulated the expression of Suppressor of cytokine signaling 3 (SOCS3), while inhibiting p-STAT3, MCP-1, IL-6, and TNF-α expression in the kidney cortex in db/db mice. And in vitro study showed that macrophage migration and MCP-1 expression induced by high glucose (HG, 30 mM) were notably reduced by 8-O-cAMP in human renal proximal tubule epithelial (HK-2) cells. In addition, 8-O-cAMP treatment restored C/EBP-ß expression in HK-2 cells and promoted C/EBP-ß translocation to the nucleus, where it transcriptionally upregulated SOCS3 expression, subsequently inhibiting STAT3 phosphorylation. Under HG conditions, siRNA-mediated knockdown of C/EBP-ß or SOCS3 in HK-2 cells partially blocked the inhibitory effect of Epac activation on the release of MCP-1. In contrast, SOCS3 overexpression inhibited HG-induced activation of STAT3 and MCP-1 expression in HK-2 cells. These findings indicate that Epac activation via 8-O-cAMP ameliorates tubulointerstitial inflammation in DN through the C/EBP-ß/SOCS3/STAT3 pathway.

miR-4486 enhances cisplatin sensitivity of gastric cancer cells by restraining the JAK3/STAT3 signalling pathway.

Along with the occurrence of cisplatin resistance, treatment on gastric cancer (GC) becomes difficult. Therefore, researches on new therapeutic methods to revert cisplatin resistance are becoming increasingly urgent. qRT-PCR was used to quantify the expression of miR-4486, JAK3 in SGC-7901 or SGC-7901/DDP cell lines. WB was utilized to analyze the expression of JAK3, STAT3 and p-STAT3 in SGC-7901/DDP cell lines. CCK-8 assay was used to determine the IC50 of cisplatin on both cell lines and cell viability of SGC-7901/DDP cell lines. The target relationship between miR-4486 and JAK3 was determined by luciferase assay. MiR-4486 expression on apoptosis of SGC-7901/DDP cell lines was determined by flow cytometry. qRT-PCR testified that miR-4486 decreased in SGC-7901/DDP cells, and the expression of miR-4486 mimic increased significantly compared with miR-4486 NC. By CCK-8 assay, the IC50 of cisplatin on both cell lines were 9 µg/mL and 81.3 µg/mL, and overexpression of miR-4486 decreased the viability of SGC-7901/DDP cells. Compared with DDP group, the expression of miR-4486 accelerated SGC-7901/DDP cells apoptosis. Dual-luciferase assay suggested that JAK3 was the target gene of miR-4486. qRT-PCR and WB proved that miR-4486/JAK3 axis inhibit the activation of JAK3/STAT3 pathway, and JAK3 overexpression can partly reverse this. As shown by CCK-8 and flow cytometry, miR-4486 overexpression decreased viability and stimulated apoptosis of SGC-7901/DDP cells. However, JAK3 overexpression can also partly revert this. miR-4486 overexpression could decrease viability and improve apoptosis of SGC-7901/DDP cells to revert its cisplatin-resistance, and the mechanism may be related to JAK3/STAT3 signalling pathway.

Loss of aryl hydrocarbon receptor suppresses the response of colonic epithelial cells to IL22 signaling by upregulating SOCS3.

IL22 signaling plays an important role in maintaining gastrointestinal epithelial barrier function, cell proliferation, and protection of intestinal stem cells from genotoxicants. Emerging studies indicate that the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, promotes production of IL22 in gut immune cells. However, it remains to be determined if AhR signaling can also affect the responsiveness of colonic epithelial cells to IL22. Here, we show that IL22 treatment induces the phosphorylation of STAT3, inhibits colonic organoid growth, and promotes colonic cell proliferation in vivo. Notably, intestinal cell-specific AhR knockout (KO) reduces responsiveness to IL22 and compromises DNA damage response after exposure to carcinogen, in part due to the enhancement of suppressor of cytokine signaling 3 (SOCS3) expression. Deletion of SOCS3 increases levels of pSTAT3 in AhR KO organoids, and phenocopies the effects of IL22 treatment on wild-type (WT) organoid growth. In addition, pSTAT3 levels are inversely associated with increased azoxymethane/dextran sulfate sodium (AOM/DSS)-induced colon tumorigenesis in AhR KO mice. These findings indicate that AhR function is required for optimal IL22 signaling in colonic epithelial cells and provide rationale for targeting AhR as a means of reducing colon cancer risk.NEW & NOTEWORTHY AhR is a key transcription factor controlling expression of IL22 in gut immune cells. In this study, we show for the first time that AhR signaling also regulates IL22 response in colonic epithelial cells by modulating SOCS3 expression.

A novel aryl-guanidinium derivative, VP79s, targets the signal transducer and activator of transcription 3 signaling pathway, downregulates myeloid cell leukaemia-1 and exhibits preclinical activity against multiple myeloma.

AIMS: We have recently described a novel guanidinium-based compound, VP79s, which induces cytotoxicity in various cancer cell lines. Here, we aim to investigate the activity of VP79s and associated mechanisms of action in multiple myeloma (MM) cells in vitro and ex vivo. MAIN METHODS: The effects of VP79s on cell viability and induction of apoptosis was examined in a panel of drug-sensitive and drug-resistant MM cell lines, as well as ex vivo patient samples and normal donor lymphocytes and platelets. Cell signaling pathways associated with the biological effects of VP79s were analysed by immunoblotting and flow cytometry. Gene expression changes were assessed by quantitative real-time PCR analysis. KEY FINDINGS: VP79s was found to rapidly inhibit both constitutively active and IL-6-induced STAT3 signaling with concurrent downregulation of the IL-6 receptors, CD130 and CD126. VP79s induced a rapid and dose-dependent downregulation of anti-apoptotic Bcl-2 family member, myeloid cell leukaemia-1 (MCL-1). VP79s enhanced bortezomib induced cell death and was also found to overcome bone marrow stromal cell induced drug resistance. VP79s exhibited activity in ex vivo patient samples at concentrations which had no effect on peripheral blood mononuclear cells, lymphocytes and platelets isolated from healthy donors. SIGNIFICANCE: As VP79s resulted in rapid inhibition of the key IL-6/STAT3 signaling pathway and downregulation of MCL-1 expression with subsequent selective anti-myeloma activity, VP79s may be a potential therapeutic agent with a novel mechanism of action in MM cells.

The mechanism underlying arsenic-induced PD-L1 upregulation in transformed BEAS-2B cells.

Chronic exposure to arsenic promotes lung cancer. Human studies have identified immunosuppression as a risk factor for cancer development. The immune checkpoint pathway of Programmed cell death 1 ligand (PD-L1) and its receptor (programmed cell death receptor 1, PD-1) is the most studied mechanism of immunosuppression. We have previously shown that prolonged arsenic exposure induced cell transformation of BEAS-2B cells, a human lung epithelial cell line. More recently our study further showed that arsenic induced PD-L1 up-regulation, inhibited T cell effector function, and enhanced lung tumor formation in the mice. In the current study, using arsenic-induced BEAS-2B transformation as a model system we investigated the mechanism underlying PD-L1 up-regulation by arsenic. Our data suggests that Lnc-DC, a long non-coding RNA, and signal transducer and activator of transcription 3 (STAT3) mediates PD-L1 up-regulation by arsenic.

Thymoquinone Induces Downregulation of BCR-ABL/JAK/STAT Pathway and Apoptosis in K562 Leukemia Cells.

OBJECTIVE: BCR ABL oncogene encodes the BCR-ABL chimeric protein, which is a constitutively activated non-receptor tyrosine kinase. The BCR-ABL oncoprotein is a key molecular basis for the pathogenesis of chronic myeloid leukemia (CML) via activation of several downstream signaling pathways including JAK/STAT pathway. Development of leukemia involves constitutive activation of signaling molecules including, JAK2, STAT3, STAT5A and STAT5B. Thymoquinone (TQ) is a bioactive constituent of Nigella sativa that has shown anticancer properties in various cancers. The present study aimed to evaluate the effect of TQ on the expression of BCR ABL, JAK2, STAT3, STAT5A and STAT5B genes and their consequences on the cell proliferation and apoptosis in K562 CML cells. METHODS: BCR-ABL positive K562 CML cells were treated with TQ. Cytotoxicity was determined by Trypan blue exclusion assay. Apoptosis assay was performed by annexin V-FITC/PI staining assay and analyzed by flow cytometry. Transcription levels of BCR ABL, JAK2, STAT3, STAT5A and STAT5B genes were evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Protein levels of JAK2 and STAT5 were determined by Jess Assay analysis. RESULTS: TQ markedly decreased the cell proliferation and induced apoptosis in K562 cells (P < 0.001) in a concentration dependent manner. TQ caused a significant decrease in the transcriptional levels of BCR ABL, JAK2, STAT3, STAT5A and STAT5B genes (P < 0.001). TQ induced a significant decrease in JAK2 and STAT5 protein levels (P < 0.001). CONCLUSION: our results indicated that TQ inhibited cell growth of K562 cells via downregulation of BCR ABL/ JAK2/STAT3 and STAT5 signaling and reducing JAK2 and STAT5 protein levels.

Curcumin inhibits proliferation and invasion of papillary thyroid carcinoma cells by inhibiting the JAK2 / STAT3 pathway.

PURPOSE: The purpose of this study was to analyze the function of curcumin to suppress the proliferative and invasive abilities of papillary thyroid carcinoma (PTC) through inhibiting the JAK2/STAT3 pathway. METHODS: After treatment of different doses of curcumin in TPC-1 and SW1736 cells, changes in viability, clonality, cell cycle, apoptosis, wound healing and invasion were determined. Western blot analyses were performed to detect protein levels of apoptosis-associated genes, JAK2 and STAT3 in TPC-1 and SW1736 cells treated with different doses of curcumin. RESULTS: Curcumin treatment dose-dependently reduced viability, clonality and metastatic ability in TPC-1 and SW1736 cells. After treatment of 10 µM or 20 µM curcumin, PTC cells were blocked in G2/M phase, and their apoptotic rate increased. Curcumin treatment downregulated Bcl-2 and upregulated Bax in PTC cells. In addition, curcumin treatment downregulated p-JAK2 and p-STAT3 in TPC-1 and SW1736 cells. CONCLUSIONS: Curcumin treatment blocks PTC cells to proliferate and invade via inhibiting the JAK2/STAT3 pathway.

Recombinant human IL-37 inhibited endometriosis development in a mouse model through increasing Th1/Th2 ratio by inducing the maturation of dendritic cells.

BACKGROUND: Endometriosis is a serious reproductive and general health consequences. Recombinant human IL-37 (rhIL-37) is an inhibitor of inflammation. METHODS: ELISA assay was performed to detect the concentration of cytokines. Flow cytometry was used to analyze cell proportion. Besides, qRT-PCR and western blotting assay were used to detect the level of gene and protein, respectively. Transwell co-culture system was used for the co-culture of dendritic cells (DCs) and CD4+T cells. RESULTS: Our data showed that rhIL-37 inhibited the development of ectopic lesions in the mice with endometriosis, increased Th1/Th2 ratio and induced DCs maturation. The co-culture system of DCs and CD4+T cells demonstrated that rhIL-37 increased Th1/Th2 cell ratio through promoting DCs maturation. Moreover, the expression of IL-4 in the DCs derived from healthy mice was inhibited by rhIL-37 treatment. rhIL-37 increased Th1/Th2 cell ratio through inhibiting IL-4 in DCs. Subsequently, our results proved that rhIL-37 promoted the maturation of DCs via inhibiting phosphorylation of STAT3. Activation of STAT3 could reverse rhIL-37-induced maturation of DCs. CONCLUSION: Overall, rhIL-37 could protect against endometriosis through increasing the ratio of Th1/Th2 cells via inducing DCs maturation and inhibiting IL-4 expression in the DCs. Furthermore, rhIL-37 induced DCs maturation by inhibiting STAT3 phosphorylation. Our data confirmed the protective effect of rhIL-37 in endometriosis. These data may provide a novel idea for the treatment of the disease.

The Interleukin-6/Signal Transducer and Activator of Transcription-3/Cystathionine γ-Lyase Axis Deciphers the Transformation Between the Sensitive and Resistant Phenotypes of Breast Cancer Cells.

Drug resistance of cancer cells is associated with redox homeostasis. The mechanism of acquired resistance of cancer cells to antitumor drugs is not well understood. Our previous studies revealed that drug resistance and highly expressed P-glycoprotein (P-gp) of MCF-7 breast cancer cells was dependent on intracellular redox homeostasis and declined capacity for scavenging reactive oxygen species (ROS). Recently, we observed that, unlike nontumorigenic cells MCF-10A, three tumorigenic breast cancer cells (MCF-7S, BT474, MDA-MB-231) reprogrammed their metabolism, highly expressed cystathionine-γ-lyase (CTH), and acquired a particular specialty to use methionine (Met) to synthesize glutathione (GSH) through the transsulfuration pathway. Interestingly, doxorubicin (adriamycin) further reprogrammed metabolism of MCF-7 cells sensitive to adriamycin (MCF-7S) and induced them to be another MCF-7 cell line resistant to adriamycin (MCF-7R) with dramatically downregulated CTH. The two MCF-7 cell lines showed distinctly different phenotypes in terms of intracellular GSH, ROS levels, expression and activity of P-gp and CTH, and drug resistance. We showed that CTH modulation or the methionine supply brought about the interconversion between MCF-7S and MCF-7R. Methionine deprivation or CTH silencing induced a resistant MCF-7R and lowered paclitaxel activity, yet methionine supplementation or CTH overexpression reversed the above effects, induced a sensitive phenotype of MCF-7S, and significantly increased the cytotoxicity of paclitaxel both in vitro and in vivo. Interleukin-6 (IL-6)/signal transducer and activator of transcription-3 (STAT3) initiated CTH expression and activity, and the effect on the resistant phenotype was exclusively dependent on CTH and ROS. This study suggests that the IL-6/STAT3/CTH axis plays a key role in the transformation between sensitive and resistant MCF-7 cells. SIGNIFICANCE STATEMENT: Cystathionine γ-lyase (CTH) plays a key role in transformation between the sensitive and resistant phenotypes of MCF-7 cells and is dependent on the interleukin-6 (IL-6)/signal transducer and activator of transcription-3 (STAT3) signaling axis. Modulation of the transsulfuration pathway on CTH or IL-6/STAT3 or methionine supplementation is beneficial for reversing the resistance of MCF-7 cells, which indicates a clinical translation potential.

TLR2 deficiency promotes IgE and inhibits IgG1 class-switching following ovalbumin sensitization.

BACKGROUND: To explore the roles of Toll-like receptor (TLR)2 in Th2 cytokine production and immunoglobulin (Ig) class switching following ovalbumin (OVA) sensitization. METHODS: TLR2-/- and wild-type C57BL/6 mice were sensitized by intraperitoneal injection with OVA. Lung pathology was assessed by hematoxylin and eosin staining. Abundance of interleukin (IL)4, IL5, IL13, and IL21 transcripts in the lungs was quantified by RT-PCR. OVA-specific IgG1, IgG2a, IgG2b, IgE and IgM were quantified by enzyme-linked immunosorbent assay. Phosphorylated signal transducer and activator of transcription (STAT)3 in lung tissue was detected by immunohistochemistry staining and nuclear factor (NF) κB activation was measured by immunofluorescence staining. STAT3 activation was inhibited using cryptotanshinone (CPT) treatment. Germline transcripts (Iµ-Cµ, Iγ-Cγ, Iα-Cα or Iε-Cε), post-recombination transcripts (Iµ-Cγ, Iµ-Cα or Iµ- Cε) and mature transcripts (VHDJH-Cγ, VHDJH-Cα or VHDJH-Cε) were analyzed from splenic B cells of OVA-sensitized wild-type mice (with or without CPT treatment) and TLR2-/- mice (with or without IL21 treatment). RESULTS: The lungs of TLR2-/- mice showed a lesser degree of inflammation than wild-type mice after OVA sensitization. Following OVA sensitization, levels of IL4, IL13, and IL21, but not IL5, were significantly lower in TLR2-/- compared with wild-type mice. Moreover, OVA-specific IgG1 and IgE titers were markedly lower and higher, respectively, in TLR2-/- mice. TLR2 deficiency inhibited STAT3 activation but not NF-κB p65 activation. CPT treatment reduced IgG1 titers via inhibition of Stat3 phosphorylation. Both TLR2 knockout and CPT treatment reduced the frequencies of Iγ1-Cγ1, Iγ3-Cγ3 and Iα-Cα transcripts, but IL21 treatment compensated for the effects of TLR2 deficiency. CONCLUSION: These results suggest a role of TLR2 in restricting OVA-sensitized lung inflammation via promotion of IgG1 and inhibition of IgE class switching regulated by IL21 and STAT3.

Atiprimod triggered apoptotic cell death via acting on PERK/eIF2α/ATF4/CHOP and STAT3/NF-ΚB axis in MDA-MB-231 and MDA-MB-468 breast cancer cells.

PURPOSE: The constitutive activation of STAT3 through receptor tyrosine kinases triggered breast cancer cell growth and invasion-metastasis. Atiprimod impacts anti-proliferative, anti-carcinogenic effects in hepatocellular carcinoma, lymphoma, multiple myeloma via hindering the biological activity of STAT3. Dose-dependent atiprimod evokes first autophagy as a survival mechanism and then apoptosis due to prolonged ER stress in pituitary adenoma cells. The therapeutic efficiency and mechanistic action of atiprimod in breast cancer cells have not been investigated yet. Thus, we aimed to modulate the pivotal role of ER stress in atiprimod-triggered apoptosis in MDA-MB-231 and MDA-MB-468 breast cancer cells. RESULTS: Dose- and time-dependent atiprimod treatment inhibits cell viability and colony formation in MDA-MB-468 and MDA-MB-231 breast cancer cells. A moderate dose of atiprimod (2 µM) inhibited STAT3 phosphorylation at Tyr705 residue and also suppressed the total expression level of p65. In addition, nuclear localization of STAT1, 3, and NF-κB was prevented by atiprimod exposure in MDA-MB-231 and MDA-MB-468 cells. Atiprimod evokes PERK, BiP, ATF-4, CHOP upregulation, and PERK (Thr980), eIF2α (Ser51) phosphorylation's. However, atiprimod suppressed IRE1α-mediated Atg-3, 5, 7, 12 protein expressions and no alteration was observed on Beclin-1, p62 expression levels. PERK/eIF2α/ATF4/CHOP axis pivotal role in atiprimod-mediated G1/S arrest and apoptosis via Bak, Bax, Bim, and PUMA upregulation in MDA-MB-468 cells. Moreover, atiprimod renders MDA-MB-231 more vulnerable to type I programmed cell death by plasmid-mediated increased STAT3 expression. CONCLUSION: Atiprimod induced prolonged ER stress-mediated apoptosis via both activating PERK/eIF2α/ATF4/CHOP axis and suppressing STAT3/NF-κB transcription factors nuclear migration in TBNC cells.

Resveratrol Is a Natural Inhibitor of Human Intestinal Mast Cell Activation and Phosphorylation of Mitochondrial ERK1/2 and STAT3.

Mast cells play a critical role as main effector cells in allergic and other inflammatory diseases. Usage of anti-inflammatory nutraceuticals could be of interest for affected patients. Resveratrol, a natural polyphenol found in red grapes, is known for its positive properties. Here, we analyzed the effects of resveratrol on FcεRI-mediated activation of mature human mast cells isolated from intestinal tissue (hiMC). Resveratrol inhibited degranulation and expression of cytokines and chemokines such as CXCL8, CCL2, CCL3, CCL4, and TNF-α in a dose-dependent manner. Further, resveratrol inhibited the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and signal transducer and activator of transcription (STAT) 3. ERK1/2 is known to be involved in cytokine expression of hiMC and to directly interact with STAT3. Mitochondrial STAT3 is phosphorylated by ERK1/2 and contributes to mast cell degranulation. We were able to isolate mitochondrial fractions from small hiMC numbers and could show that activation of mitochondrial STAT3 and ERK1/2 in hiMC was also inhibited by resveratrol. Our results indicate that resveratrol inhibits hiMC activation by inhibiting the phosphorylation of mitochondrial and nuclear ERK1/2 and STAT3, and it could be considered as an anti-inflammatory nutraceutical in the treatment of mast cell-associated diseases.

Inflammatory repercussions in female steroid responsive glands after perinatal exposure to bisphenol A and 17-ß estradiol.

The mammary gland (MG) and female prostate are plastic reproductive organs which are highly responsive to hormones. Thus, endocrine disruptors, such as bisphenol A (BPA) and exogenous estrogens, negatively affect glandular homeostasis. In addition to previously described alterations, changes in inflammatory markers expression also trigger the development of a microenvironment that contributes to tumor progression. The current work aimed to evaluate the inflammatory responses of the MG and prostate gland to BPA (50 µg/kg) and 17-ß estradiol (35 µg/kg) exposure during the perinatal window of susceptibility. The results showed that at 6 months of age there was an increase in the number of phospho-STAT3 (P-STAT3) positive cells in the female prostate from animals perinatally exposed to 50 µg/kg BPA daily. In addition, the number of macrophages increased in these animals in comparison with nonexposed animals, as shown by the F4/80 marker. Despite an increase in the incidence of lobuloalveolar and intraductal hyperplasia, the MG did not show any difference in the expression of the four inflammatory markers evaluated: tumor necrosis factor-α, COX-2, P-STAT3, and F4/80. Analysis of both glands from the same animal led to the conclusion that exposure to endocrine disruptors during the perinatal window of susceptibility leads to different inflammatory responses in different reproductive organs. As the prostate is more susceptible to these inflammatory mechanisms, it is reasonable to affirm that possible neoplastic alterations in this organ are related to changes in the inflammatory pattern of the stroma, a characteristic that is not evident in the MG.