H19 promotes cholestatic liver fibrosis by preventing ZEB1-mediated inhibition of epithelial cell adhesion molecule

Based on our recent finding that disruption of bile acid (BA) homeostasis in mice results in the induction of hepatic long noncoding RNA H19 expression, we sought to elucidate the role of H19 in cholestatic liver fibrosis. Hepatic overexpression of H19RNA augmented bile duct ligation (BDL)-induced liver fibrosis, which was accompanied by the elevation of serum alanine aminotransferase, aspartate aminotransferase, bilirubin, and BA levels. Multiple genes related to liver fibrosis, inflammation, and biliary hyperplasia were increased in H19-BDL versus null-BDL mice, whereas genes in BA synthesis were decreased. Livers and spleens of H19-BDL mice showed significant enrichment of CD3+γδ+, interleukin-4, and interleukin-17 producing CD4+ and CD8+ immune cell populations. H19 down-regulated hepatic zinc finger E-box-binding homeobox 1 (ZEB1) but up-regulated epithelial cell adhesion molecule (EpCAM) and SRY (sex determining region Y)-box 9 expression. Mechanistically, ZEB1 repressed EpCAM promoter activity and gene transcription. H19RNA impeded ZEB1's inhibitory action by interacting with ZEB1 protein to prevent its binding to the EpCAM promoter. Hepatic overexpression of ZEB1 or knockdown of EpCAM diminished H19-induced fibrosis; the latter was also prevented in H19^-/- mice. H19RNA was markedly induced by bile acids in mouse small cholangiocytes and to a lesser extent in mouse large cholangiocytes. The up-regulation of H19RNA and EpCAM correlated positively with the down-regulation of ZEB1 in primary sclerosing cholangitis and primary biliary cirrhosis liver specimens.

CONCLUSION

The activation of hepatic H19RNA promoted cholestatic liver fibrosis in mice through the ZEB1/EpCAM signaling pathway. (Hepatology 2017;66:1183-1196).

TLR7 Signaling Regulates Th17 Cells and Autoimmunity: Novel Potential for Autoimmune Therapy

Innate regulation through TLR signaling has been shown to be important for promoting T cell subset development and function. However, limited information is known about whether differential TLR signaling can selectively inhibit Th17 and/or Th1 cells, which are important for controlling excessive inflammation and autoimmune responses. In this article, we demonstrate that activation of TLR7 signaling in T cells can inhibit Th17 cell differentiation from naive T cells and IL-17 production in established Th17 cells. We further report that downregulation of STAT3 signaling is responsible for TLR7-mediated inhibition of Th17 cells due to induction of suppressor of cytokine signaling 3 and 5. TLR7-mediated suppression of Th17 cells does not require dendritic cell involvement. In addition, we show that TLR7 signaling can suppress Th1 cell development and function through a mechanism different from Th17 cell suppression. Importantly, our complementary in vivo studies demonstrate that treatment with the TLR7 ligand imiquimod can inhibit Th1 and Th17 cells, resulting in the prevention of, and an immunotherapeutic reduction in, experimental autoimmune encephalomyelitis. These studies identify a new strategy to manipulate Th17/Th1 cells through TLR7 signaling, with important implications for successful immunotherapy against autoimmune and inflammatory diseases.

Controlling T cell development and function via innate Toll-like receptor signaling for autoimmune therapy

Innate regulation through Toll-like receptor (TLR) signaling has been shown to be important for promoting T cell subset development and function. However, limited information is known about whether differential TLR signaling can selectively inhibit Th17 and/or Th1 cells, important for controlling excessive inflammation and autoimmune responses. Here we demonstrate that activation of TLR7 signaling in T cells can inhibit both Th17 cell differentiation from naïve T cells and IL-17 production in established Th17 cells. We further report that down-regulation of STAT3 signaling is responsible for TLR7-mediated inhibition of Th17 cells due to induction of SOCS3 and SOCS5. TLR7-mediated suppression of Th17 cells does not require DC involvement. In addition, we show that TLR7 signaling can suppress Th1 cell development and function due to a mechanism different from Th17 cell suppression. Importantly, our complementary in vivo studies demonstrate that treatment with the TLR7 ligand imiquimod can inhibit both Th1 and Th17 cells, resulting in prevention of and immunotherapeutic reduction in experimental autoimmune encephalomyelitis (EAE). These studies identify a new strategy to manipulate Th17/Th1 cells through TLR7 signaling, with important implications for successful immunotherapy against autoimmune and inflammatory diseases.

Inhibition of DNA2 nuclease as a therapeutic strategy targeting replication stress in cancer cells

Replication stress is a characteristic feature of cancer cells, which is resulted from sustained proliferative signaling induced by activation of oncogenes or loss of tumor suppressors. In cancer cells, oncogene-induced replication stress manifests as replication-associated lesions, predominantly double-strand DNA breaks (DSBs). An essential mechanism utilized by cells to repair replication-associated DSBs is homologous recombination (HR). In order to overcome replication stress and survive, cancer cells often require enhanced HR repair capacity. Therefore, the key link between HR repair and cellular tolerance to replication-associated DSBs provides us with a mechanistic rationale for exploiting synthetic lethality between HR repair inhibition and replication stress. DNA2 nuclease is an evolutionarily conserved essential enzyme in replication and HR repair. Here we demonstrate that DNA2 is overexpressed in pancreatic cancers, one of the deadliest and more aggressive forms of human cancers, where mutations in the KRAS are present in 90–95% of cases. In addition, depletion of DNA2 significantly reduces pancreatic cancer cell survival and xenograft tumor growth, suggesting the therapeutic potential of DNA2 inhibition. Finally, we develop a robust high-throughput biochemistry assay to screen for inhibitors of the DNA2 nuclease activity. The top inhibitors were shown to be efficacious against both yeast Dna2 and human DNA2. Treatment of cancer cells with DNA2 inhibitors recapitulates phenotypes observed upon DNA2 depletion, including decreased DNA double strand break end resection and attenuation of HR repair. Similar to genetic ablation of DNA2, chemical inhibition of DNA2 selectively attenuates the growth of various cancer cells with oncogene-induced replication stress. Taken together, our findings open a new avenue to develop a new class of anticancer drugs by targeting druggable nuclease DNA2. We propose DNA2 inhibition as new strategy in cancer therapy by targeting replication stress, a molecular property of cancer cells that is acquired as a result of oncogene activation instead of targeting currently undruggable oncoprotein itself such as KRAS.

Molecular Pathophysiology of Congenital Long QT Syndrome

Ion channels represent the molecular entities that give rise to the cardiac action potential, the fundamental cellular electrical event in the heart. The concerted function of these channels leads to normal cyclical excitation and resultant contraction of cardiac muscle. Research into cardiac ion channel regulation and mutations that underlie disease pathogenesis has greatly enhanced our knowledge of the causes and clinical management of cardiac arrhythmia. Here we review the molecular determinants, pathogenesis, and pharmacology of congenital Long QT Syndrome. We examine mechanisms of dysfunction associated with three critical cardiac currents that comprise the majority of congenital Long QT Syndrome cases: 1) IKs, the slow delayed rectifier current; 2) IKr, the rapid delayed rectifier current; and 3) INa, the voltage-dependent sodium current. Less common subtypes of congenital Long QT Syndrome affect other cardiac ionic currents that contribute to the dynamic nature of cardiac electrophysiology. Through the study of mutations that cause congenital Long QT Syndrome, the scientific community has advanced understanding of ion channel structure-function relationships, physiology, and pharmacological response to clinically employed and experimental pharmacological agents. Our understanding of congenital Long QT Syndrome continues to evolve rapidly and with great benefits: genotype-driven clinical management of the disease has improved patient care as precision medicine becomes even more a reality.

The Influenza A Virus Non-structural Protein NS1 Upregulates The Expression of Collagen Triple Helix Repeat Containing 1 Protein

Influenza A virus (IAV) infection induces a strong immune response and regulates the expression of many host proteins. The collagen triple helix repeat containing 1 (CTHRC1) protein is a secreted protein that exhibits increased expression during the viral infection process. However, the regulatory function of IAV on CTHRC1 expression is obscure. In this study, we investigated the effect of IAV on CTHRC1 expression and its regulatory mechanism. A total of 106 serum specimens from healthy people and 80 serum specimens from patients infected with IAV were collected. The CTHRC1 levels in the sera from the IVA patients and healthy individuals were measured using an enzyme-linked immunosorbent assay (ELISA), and the differences were statistically analysed. A549 cells were infected with the IAV or delNS1 virus. Additionally, A549 cells were cotransfected with a eukaryotic non-structural NS1 protein gene expression plasmid and the CTHRC1 gene promoter reporter plasmid (pCTHRC1-Luc), and, the luciferase activities were assessed. The CTHRC1 mRNA and protein expression were detected using reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. The serum CTHRC1 level was significantly higher in the IAV patients than in the healthy individuals. IAV upregulated the CTHRC1 mRNA and protein expression. The non-structural NS1 protein specifically activated CTHRC1 gene promoter activity and upregulated CTHRC1 mRNA and protein expression. The activation function had a dose-dependent effect, indicating that influenza virus upregulated CTHRC1 expression through its NS1 protein.

Abstract 5125: Immunomodulatory activity of bitter melon extract in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer and leading cause of cancer related mortality worldwide. Despite the advancement in treatment procedures the overall survival rate of patients has not considerably enhanced in the past few decades. Therefore, new strategies to achieve a favorable response for the improvement in the prognosis of HNSCC are urgently needed. In this study we examined the immune modulatory activity of bitter melon extract (BME) in HNSCC tumor microenvironment. For this, mouse head and neck cancer (SCCVII) cells were subcutaneously injected into the flanks of C3H mice. BME was fed orally, and tumor growth was evaluated. We observed that BME treatment significantly inhibits the tumor growth in BME fed mice as compared to control group. Flow cytometry data showed that BME treatment not only decreases the infiltrating T regulatory (Treg) cells in the tumor but also in splenocytes. Additionally, BME treatment reduces Th17 cell population in the tumor and augments in the spleen. However, BME treatment did not alter Th1 and Th2 populations. Further study suggested that BME inhibits cell proliferation as evident from low expression of PCNA and c-Myc in the tumors of BME fed mice as compared to that of control group. To our knowledge, this is the first report showing BME exerts immunomodulatory effect in regressing HNSCC tumor growth in preclinical model.

Citation Format: Sourav Bhattacharya, Robert Steele, Naoshad Muhammad, Guangyong Peng, Ratna B. Ray. Immunomodulatory activity of bitter melon extract in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5125.

Abstract 375: Combination of MEK and PI3K inhibition in BRAF wild-type and mutant melanoma

Introduction: Targeted therapy against BRAF-mutated melanoma with BRAF and MEK inhibitors has shown clinical efficacy. However, resistance to therapy occurred and lead to therapy failure. We evaluated the effect of combining downstream inhibition of RAS/RAF pathways with MEK (AZD6244) and PI3K (XL765) inhibition on BRAF wild-type and mutant melanoma with variable expression of NRAS as possible therapeutic option.

Methods: Fifteen melanoma cell lines were screened for BRAF mutation status and NRAS expression. BRAF wildtype (Mel628, Mel1098) and BRAF-mutated (Mel1861, Mel1890) cell lines were selected. Drug concentration study with AZD6244 (A, 2.5-40 uM) and XL765 (X, 2.5-40 uM) were performed on Mel628 cells. Subsequently, cells were treated with A (5 uM), X (5 uM), or combination. Cell proliferation assay was performed using Cell Titer Blue assay. Western blotting was performed to for expression of PARP, caspase-9, LC3A/B, Beclin1, pMEK/MEK, pERK/ERK, p-P70S6/P70S6, and p4EBP1/4EBP1. GAPDH was used as internal control. Apoptosis was analyzed using FITC Annexin V Apoptosis Detection Kit (BD Biosciences). Cell migration assay was performed by artificial wounding of melanoma cell monolayer and observing migration of cells into the wound up to 72 hours. Data were presented as means ± SD for the three separate experiments. For comparison between groups, the student's t test was used and p< 0.05 was considered to be statically significant.

Results: There was dose-dependent inhibition of melanoma cell proliferation with both A and X. Combination A and X had synergistic effect on the anti-melanoma proliferative effect of BRAF mutated cells regardless of expression level of NRAS. Significantly increased apoptosis by Annnexin V assay was detected in BRAF mutated cells (Mel 1860 and Mel1890). Significantly increased expression (p<0.05) of apoptosis markers (PARP and caspases-9) were observed in cells treated with A+X compared with A or X alone. Enhanced phosphorylation of ERK and P70S6 were observed in BRAF mutated cells. No significant difference in autophagy markers (LC3A/B and Beclin1) were observed between A, X, or combination. Variable to minimal additive effect of the combination treatment was observed in BRAF wild-type cells in terms of proliferation, apoptosis, and autophagy. The combination of A and X significantly inhibited melanoma migration compared with either drug alone regardless of BRAF mutation status in the wounding assay model.

Conclusion: We have observed a synergistic effect on suppressing BRAF-mutated melanoma proliferation with combined inhibition of MEK and PI3K. The effect is not dependent on NRAS expression levels of melanoma.

Citation Format: Yanping Zhang, Guangyong Peng, Eddy C. Hsueh. Combination of MEK and PI3K inhibition in BRAF wild-type and mutant melanoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 375.

Vasohibin-1 suppresses colon cancer

Vasohibin-1 (VASH1) is an endogenous angiogenesis inhibitor.However, the clinical relevance of VASH1 in colon cancer and its regulations on cancer angiogenesis and cancer cell biological characteristics are still unknown. Here we showed that stromal VASH1 levels were negatively correlated with tumor size, advanced clinical stage and distant metastases in colon cancer patients. Overexpression of VASH1 in colon cancer cells induced apoptosis and senescence, inhibiting cancer cell growth and colony formation in vitro and tumor growth in vivo. In addition, knockdown of VASH1 in cancer cells promoted cell growth, adhesion and migration in vitro, and enhanced tumorigenesis and metastasis in vivo.

CD4+ and CD8+ T cells have opposing roles in breast cancer progression and outcome

The Cancer Immunoediting concept has provided critical insights suggesting dual functions of immune system during the cancer initiation and development. However, the dynamics and roles of CD4⁺ and CD8⁺ T cells in the pathogenesis of breast cancer remain unclear. Here we utilized two murine breast cancer models (4T1 and E0771) and demonstrated that both CD4⁺ and CD8⁺ T cells were increased and involved in immune responses, but with distinct dynamic trends in breast cancer development. In addition to cell number increases, CD4⁺ T cells changed their dominant subsets from Th1 in the early stages to Treg and Th17 cells in the late stages of the cancer progression. We also analyzed CD4⁺ and CD8⁺ T cell infiltration in primary breast cancer tissues from cancer patients. We observed that CD8⁺ T cells are the key effector cell population mediating effective anti-tumor immunity resulting in better clinical outcomes. In contrast, intra-tumoral CD4⁺ T cells have negative prognostic effects on breast cancer patient outcomes. These studies indicate that CD4⁺ and CD8⁺ T cells have opposing roles in breast cancer progression and outcomes, which provides new insights relevant for the development of effective cancer immunotherapeutic approaches.

Targeting T cell senescence in the tumor microenvironment for tumor immunotherapy

Understanding the molecular mechanisms involved in creating and sustaining the tumor suppressive microenvironment is critical for the development of novel anti-tumor therapeutic strategies. Regulatory T cells (Treg) are a key player for the tumor immunosuppressive microenvironment. However, the molecular processes and functions of suppressed responder T cells mediated by Treg cells remain largely unknown. We discovered a novel suppressive mechanism whereby human Treg cells induce senescence in naïve and effector T cells that then exhibit potent suppressive activity and amplify immune suppression. Treg-induced senescent T cells were distinctly different from the exhausted or anergic T cells based on the transcriptome analyses and phenotypic profiles. We further identified that the nuclear kinase ataxia-telangiectasia mutated protein (ATM)-induced DNA damage was critical and the main cause for the induction of responder T cell senescence and dysfunction mediated by human Treg cells. In addition, MAPK ERK1/2 and p38 were involved in the regulation of senescence process in responder T cells. Importantly, we further revealed that human Treg-induced senescence and suppressor function could be blocked by specific ATM signaling and/or ERK1/2 and p38 signaling inhibition in vitro and in vivo in animal models. Our studies identify a novel molecular mechanism responsible for human Treg cell suppression, and provide new insights relevant for the development of strategies capable of preventing and/or reversing Treg-induced immune suppression for tumor immunotherapy.

Funding Support: Supported by the grants from the Melanoma Research Alliance, American Cancer Society and the National Institutes of Health.

Probenecid protects against cerebral ischemia/reperfusion injury by inhibiting lysosomal and inflammatory damage in rats

Probenecid has been used for decades to treat gout, and recent studies have revealed it is also a specific inhibitor of the pannexin-1 channel. It has been reported that the pannexin-1 channel is involved in ischemic injury. Here, we investigated the neuroprotective effect and the possible mechanisms of action of probenecid in global cerebral ischemia/reperfusion (I/R) injury in rats. Twenty minutes of transient global cerebral I/R injury was induced using the four-vessel occlusion (4-VO) method in male Sprague-Dawley rats. Different doses of probenecid were administered intravenously, intraperitoneally, or by gavage before or after reperfusion. Probenecid via all three routes protected against CA1 neuronal death when given before reperfusion. This protective effect continued when probenecid was given at 2h after reperfusion, but not at 6h. Interestingly, the protective effect regained if probenecid was given continuously for 7days after reperfusion. The release of cathepsin B and overexpression of calpain-1 after reperfusion were inhibited, while the upregulation of Hsp70 was strengthened by probenecid pre-treatment. Furthermore, the activation and proliferation of microglia and astrocytes after I/R injury were suppressed by continuous given for 7days, but only partly by a single dose at 6h of reperfusion. Thus, our data indicate that probenecid protects against transient global cerebral I/R injury probably by inhibiting calpain-cathepsin pathway and the inflammatory reaction.

Abstract 1196: Enhancement of anti-melanoma effect of BRAF and MEK inhibition by metformin

Introduction: Metformin has been shown to inhibit human cancer cell growth via activation of MAP kinase with resultant inhibition of mTOR signaling pathway. Recent clinical evidence demonstrated the anti-melanoma effect of combined mutant BRAF inhibition and MEK inhibition. We determined the effect of metformin in combination with mutant BRAF and MEK inhibition on melanoma proliferation and the possible mechanisms.

Methods: Human melanoma cells (SK-23, Mel888, Mel1861) were treated with Metformin (1-20 mM), PLX4032 (a mutant BRAF inhibitor, 1-20 uM), AZD6244 (a MEK inhibitor, 1-20 uM), or combination. Cell proliferation assay was performed using Cell Titer Blue assay. Western blotting was performed to determine the expression of PARP, caspases-9, LC3A/B,Beclin1, pERK, pMEK, AMPKa, p70S6, and p4E-BP1. GAPDH was used as internal control. Autophagy was further analyzed with immunofluorescence with LC-3 and NECN1 anti-antibody for visualization of lysosomal morphology and evaluated under the Nikon Eclipse Ti microscope (20×). DAPI was used to counter stain the nucleus. Apoptosis was further analyzed with flow cytometry using FITC Annexin V Apoptosis Detection Kit (BD Biosciences). Data were presented as means ± SD for the three separate experiments. For comparison between groups, the student's t test was used and p< 0.05 was considered to be statically significant.

Results: There was dose-dependent inhibition of melanoma cell proliferation with either metformin(M), PLX4032(P), and AZD6244(A). Addition of M to PA combination had synergistic effect on the anti-melanoma proliferative effect of PA. Significantly increased expression (p<0.05) of apoptosis markers (PARP and caspases-9) and autophagy markers (LC3B and Beclin1) were observed in cells treated with PAM compared with PA. Enhanced induction of autophagy with the triple drugs was confirmed by visualization of autophagosome and autolysosome formation on immunofluorescence. Synergistic effect on apoptosis was confirmed on Annexin V assay. The PAM combination treatment also lead to significant enhancement of AMPK activation and increased phosphorylation of AMPKα at Thr-172 compared with metformin alone (p<0.01). The addition of M to PA combination resulted in inhibition of mTOR signaling with decreased phosphorylation of p70S6K and 4E-BP1 in treated cancer cells, when compared with PA or M alone.

Conclusion: We have observed a synergistic effect on suppressing human melanoma proliferation with the addition of metformin to combined inhibition of mutant BRAF and MEK. The synergism is due to enhanced inhibition of mTOR signaling pathways.

Citation Format: Yanping Zhang, Guangyong Peng, Eddy C. Hsueh. Enhancement of anti-melanoma effect of BRAF and MEK inhibition by metformin. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1196. doi:10.1158/1538-7445.AM2015-1196

TLR8 signaling enhances tumor immunity by preventing tumor-induced T-cell senescence

Accumulating evidence suggests the immunosuppressive microenvironments created by malignant tumors represent a major obstacle for effective anti-tumor immunity. A better understanding of the suppressive mechanisms mediated by tumor microenvironments and the development of strategies to reverse the immune suppression are major challenges for the success of tumor immunotherapy. Here, we report that human tumor cells can induce senescence in naïve/effector T cells, exhibiting potent suppressive function in vitro and in vivo. We further show that tumor-derived endogenous cyclic adenosine monophosphate (cAMP) is responsible for the induction of T-cell senescence. Importantly, activation of TLR8 signaling in tumor cells can block the induction and reverse the suppression of senescent naïve and tumor-specific T cells in vitro and in vivo, resulting in enhanced anti-tumor immunity. These studies identify a novel mechanism of human tumor-mediated immune suppression and provide a new strategy to reverse tumor immunosuppressive effects for tumor immunotherapy.

Efficacy and Safety of Abacavir Plus Lamivudine Versus Didanosine Plus Stavudine When Combined with a Protease Inhibitor, a Nonnucleoside Reverse Transcriptase Inhibitor, or Both in HIV-1 Positive Antiretroviral-Naive Persons

PURPOSE

The combination of abacavir + lamivudine (ABC+3TC) versus didanosine + stavudine (ddI+d4T), each combined with other classes of antiretrovirals (ARVs) in ARV-naive patients, was compared for the combined endpoint of time to plasma HIV RNA >50 copies/mL (at or after the 8-month visit) or death (primary endpoint) in a nested substudy of an ongoing multicenter randomized trial.

METHOD

The substudy enrolled 182 patients; mean HIV RNA and CD4+ cell counts at baseline were 5.1 log10 copies/mL and 212 cells/mm3, respectively.

RESULTS

After a median follow-up of 28 months, rates of primary endpoint were 57.2 and 67.8 per 100 person-years for the ABC+3TC and ddI+d4T groups (hazard ratio [HR]=0.81, 95% confidence interval [CI] 0.58-1.14, p=.23).

CONCLUSION

There was a trend for treatments containing ABC+3TC to be better than treatments containing ddI+d4T with respect to HIV RNA decreases, CD4+ cell count increases, and tolerability.

Controlling T cell senescence in the tumor microenvironment for tumor immunotherapy

Understanding molecular mechanisms involved in creating and sustaining the tumor suppressive microenvironment is critical for the development of novel antitumor therapeutic strategies. We have identified the induction of T cell senescence as a novel mechanism utilized by human tumor cells to induce immune suppression, and provided a new strategy using TLR8 ligands to reverse tumor immunosuppressive effects for tumor immunotherapy.

Benzo(a)pyrene-7,8-diol-9,10-epoxide induced p53-independent necrosis via the mitochondria-associated pathway involving Bax and Bak activation

Benzo(a)pyrene-7,8-diol-9,10-epoxide (BPDE) is a highly reactive DNA damage agent and can induce cell death through both p53-independent and -dependent pathways. However, little is known about the molecular mechanisms of p53-independent pathways in BPDE-induced cell death. To understand the p53-independent mechanisms, we have now examined BPDE-induced cytotoxicity in p53-deficient baby mouse kidney (BMK) cells. The results showed that BPDE could induce Bax and Bak activation, cytochrome c release, caspases activation, and necrotic cell death in the BMK cells. Bax and Bak, two key molecules of mitochondrial permeability transition pore, were interdependently activated by BPDE, with Bax and Bak translocation to and Bax/Bak homo-oligomerization in mitochondria, release of cytochrome c was induced. Importantly, cytochrome c release and necrotic cell death were diminished in BMK cells (Bax−/−), BMK cells (Bak−/−), and BMK cells (Bax−/−/Bak−/−). Furthermore, overexpression of Bcl-2 could ameliorate BPDE-induced cytochrome c release and necrosis. Together the findings suggested that BPDE-induced necrosis was modulated by the p53-independent pathway, which was related to the translocation of Bax and Bak to mitochondria, release of cytochrome c, and activation of caspases.

Targeting gammadelta regulatory T cell recruitment for breast cancer immunotherapy (TUM2P.904)

Immunosuppressive microenvironments induced by regulatory T cells (Treg) present a major barrier for successful anti-tumor immunotherapy. Understanding the mechanisms for the accumulation of different subtypes of Treg cells in the immunosuppressive tumor microenvironment is essential to improving cancer treatment. Enriched gammadelta1 T cell populations in tumor-infiltrating lymphocytes (TILs) suppress T cell responses and dendritic cell maturation in breast cancer, where their presence is correlated negatively with clinical outcomes. However, mechanism(s) that explain the increase in this class of gammadelta Treg cells in breast cancer patients have yet to be elucidated. In this study, we showed that IP-10 secreted by breast cancer cells attracted gammadelta Treg cells. Using neutralizing antibodies against chemokines secreted by breast cancer cells, we found that IP-10 was the only functional chemokine that causes gammadelta Treg cells to migrate toward breast cancer cells. In a humanized NSG mouse model, human breast cancer cells attracted gammadelta Treg cells as revealed by a live cell imaging system. IP-10 neutralization in vivo inhibited migration and trafficking of gammadelta Treg cells into breast tumor sites, enhancing tumor immunity mediated by tumor-specific T cells. Together, our studies show how gammadelta Treg cells accumulate in breast tumors, providing a rationale for their immunological targeting to relieve immunosuppression in the tumor microenvironment.

Synthesis factors affecting the catalytic performance and stability of Ru/C catalysts for supercritical water gasification

Improvement of the catalytic performance of Ru/C catalysts by selecting acetone as a solvent during the catalyst preparation.