A Combination of Glutaminase Inhibitor 968 and PD-L1 Blockade Boosts the Immune Response against Ovarian Cancer.

Programmed cell death 1 ligand (PD-L1) blockade has been used therapeutically in the treatment of ovarian cancer, and potential combination treatment approaches are under investigation to improve the treatment response rate. The increased dependence on glutamine is widely observed in various type of tumors, including ovarian cancer. Kidney-type glutaminase (GLS), as one of the isotypes of glutaminase, is found to promote tumorigenesis. Here, we have demonstrated that the combined treatment with GLS inhibitor 968 and PD-L1 blockade enhances the immune response against ovarian cancer. Survival analysis using the Kaplan-Meier plotter dataset from ovarian cancer patients revealed that the expression level of GLS predicts poor survival and correlates with the immunosuppressive microenvironment of ovarian cancer. 968 inhibits the proliferation of ovarian cancer cells and enhances granzyme B secretion by CD8+ T cells as detected by XTT assay and flow cytometry, respectively. Furthermore, 968 enhances the apoptosis-inducing ability of CD8+ T cells toward cancer cells and improves the treatment effect of anti-PD-L1 in treating ovarian cancer as assessed by Annexin V apoptosis assay. In vivo studies demonstrated the prolonged overall survival upon combined treatment of 968 with anti-PD-L1 accompanied by increased granzyme B secretion by CD4+ and CD8+ T cells isolated from ovarian tumor xenografts. Additionally, 968 increases the infiltration of CD3+ T cells into tumors, possibly through enhancing the secretion of CXCL10 and CXCL11 by tumor cells. In conclusion, our findings provide a novel insight into ovarian cancer cells influence the immune system in the tumor microenvironment and highlight the potential clinical implication of combination of immune checkpoints with GLS inhibitor 968 in treating ovarian cancer.

HPV-induced Nurr1 promotes cancer aggressiveness, self-renewal, and radioresistance via ERK and AKT signaling in cervical cancer.

Human papillomavirus (HPV) is the etiological agent of cervical cancer; however, the mechanisms underlying HPV-mediated carcinogenesis remain poorly understood. Here, we showed that nuclear receptor related-1 protein (Nurr1) was upregulated in primary cervical cancer tissue-derived spheroid cells and HPV-positive cell lines, and Nurr1 upregulation was correlated with cancer grade. Nurr1 promoted cell proliferation, migration, invasion, and anchorage-independent cell growth. In addition to its effect on cancer aggressiveness, Nurr1 enhanced the self-renewal ability of cells in vitro and in vivo, underscoring the importance of Nurr1 in maintaining the stemness of cancer stem-like cells (CSLCs). Mechanistically, Nurr1 independently activated the MEK/ERK and PI3K/Akt/mTOR signaling cascades. The MEK inhibitor trametinib (GSK) and PI3K/mTOR dual inhibitor dactolisib (BEZ) were shown to abrogate Nurr1-augmented tumorigenesis by upregulating p21 and p27 expression and by suppressing MMP9 and KLF4 expression. We provided further evidence that BEZ, but not GSK, could abolish Nurr1-enhanced radioresistance, suggesting its potential value for radiosensitizing CSLCs in the clinical setting. This study highlights the unprecedented roles of Nurr1 and elucidates mechanisms by which Nurr1 promotes tumor progression and radioresistance, providing a novel therapeutic strategy for cervical cancer treatment.

Role of Nurr1 in Carcinogenesis and Tumor Immunology: A State of the Art Review.

Nuclear receptor related-1 protein (Nurr1), coded by an early response gene, is involved in multiple cellular and physiological functions, including proliferation, survival, and self-renewal. Dysregulation of Nurr1 has been frequently observed in many cancers and is attributed to multiple transcriptional and post-transcriptional mechanisms. Besides, Nurr1 exhibits extensive crosstalk with many oncogenic and tumor suppressor molecules, which contribute to its potential pro-malignant behaviors. Furthermore, Nurr1 is a key player in attenuating antitumor immune responses. It not only potentiates immunosuppressive functions of regulatory T cells but also dampens the activity of cytotoxic T cells. The selective accessibility of chromatin by Nurr1 in T cells is closely associated with cell exhaustion and poor efficacy of cancer immunotherapy. In this review, we summarize the reported findings of Nurr1 in different malignancies, the mechanisms that regulate Nurr1 expression, and the downstream signaling pathways that Nurr1 employs to promote a wide range of malignant phenotypes. We also give an overview of the association between Nurr1 and antitumor immunity and discuss the inhibition of Nurr1 as a potential immunotherapeutic strategy.

CD109 mediates tumorigenicity and cancer aggressiveness via regulation of EGFR and STAT3 signalling in cervical squamous cell carcinoma.

BACKGROUND: CD109 was involved in the tumorigenesis and progression of various cancers via TGF-ß1 signalling and STAT3 activation. As CD109 is strongly expressed in cervical squamous cell carcinoma, this study was conducted to investigate its functional characteristics in cervical cancer. METHODS: CD109 expression was examined by immunohistochemistry (IHC) with cervical tissue microarray. The effects of CD109 expression were examined on migration, cell proliferation, spheroid formation and soft-agar colony-formation assay. Meanwhile, cervical cancer cell lines with high CD109 expression were chosen for the functional study using siRNA knockdown and CRISPR/Cas9 knockout. RESULTS: IHC demonstrated an upregulation of CD109 in the cell membrane of cervical squamous cell carcinoma. CD109( + ) cells isolated by flow-cytometric sorting displayed enhanced migration, cell proliferation, sphere-forming and anchorage-independent cell growth ability. In contrast, silencing of CD109 expression could reverse the in vitro and in vivo tumorigenic and aggressive properties. Furthermore, CD109 induced EGFR-mediated STAT3 phosphorylation known to be responsible for cell migration, proliferation and maintenance of CSC phenotype. CONCLUSION: Abundant CD109( + ) populations in cervical cancer cells potentially contributed to carcinogenesis and aggressiveness, whereas silencing of CD109 expression could reverse those properties. CD109 mediates cervical tumorigenicity and aggressiveness via CD109/EGFR/STAT3 signalling.

Infiltration of T cells promotes the metastasis of ovarian cancer cells via the modulation of metastasis-related genes and PD-L1 expression.

Due to its high ability to disseminate, ovarian cancer remains one of the largest threats to women's health, worldwide. Evidence showed that the immune cells infiltrating the tumor microenvironment are crucial in mediating metastasis. Therefore, it is necessary to understand which types of immune cells are involved in metastasis, and to determine the mechanisms by which they influence the process. By immunohistochemistry, we found that higher concentrations of intratumoral CD8+ T cells were found to be correlated with an advanced grade and stage of ovarian cancer. Additionally, the infiltration of stromal CD8+ T cells was also significantly higher in tissues with advanced stages and metastatic tumors. A positive correlation between the infiltration of FoxP3+ Treg cells and histological grade was also observed, regardless of location. PD-L1 expression in metastatic tumors was also higher than that in paired primary ovarian tumors. Transwell migration and invasion assays revealed the increased migration and invasion of ovarian cancer cell lines (A2780CP and ES2) and ascites-derived ovarian cancer cells following co-culturing with CD8+ T cells. Enhanced expression of MMP-9, uPA, VEGF, bFGF, IL-8, IL-10, and PD-L1 by cancer cells following co-culturing with CD8+ T cells were also detected by qPCR, ELISA or flow cytometry. In conclusion, our findings suggest that the infiltrated T cells could promote the development of ovarian cancer, and provide another mechanism of immune evasion mediated by T cells.

Ascites-derived ALDH+CD44+ tumour cell subsets endow stemness, metastasis and metabolic switch via PDK4-mediated STAT3/AKT/NF-κB/IL-8 signalling in ovarian cancer.

BACKGROUND: Ovarian cancer is characterised by frequent recurrence due to persistent presence of residual cancer stem cells (CSCs). Here, we identify and characterise tumour subsets from ascites-derived tumour cells with stemness, metastasis and metabolic switch properties and to delineate the involvement of pyruvate dehydrogenase kinase 4 (PDK4) in such process. METHODS: Ovarian cancer cells/cell lines derived from ascites were used for tumourspheres/ALDH+CD44+ subset isolation. The functional roles and downstream signalling of PDK4 were explored. Its association with clinical outcome of ovarian cancer was analysed. RESULTS: We demonstrated enhanced CSC characteristics of tumour cells derived from ovarian cancer ascites, concomitant with ALDH and CD44 subset enrichment and high PDK4 expression, compared to primary tumours. We further showed tumourspheres/ALDH+CD44+ subsets from ascites-derived tumour cells/cell lines with CSC properties and enhanced glycolysis. Clinically, PDK4 expression was correlated with aggressive features. Notably, blockade of PDK4 in tumourspheres/ALDH+CD44+ subsets led to inhibition of CSC characteristics, glycolysis and activation of STAT3/AKT/NF-κB/IL-8 (signal transducer and activator of transcription 3/protein kinases B/nuclear factor-κB/interleukin-8) signalling. Conversely, overexpression of PDK4 in ALDH-CD44- subsets exerted the opposite effects. CONCLUSION: Ascites-derived ALDH+CD44+ tumour cell subsets endow stemness, metastatic and metabolic switch properties via PDK4-mediated STAT3/AKT/NF-κB/IL-8 signalling, suggesting PDK4 as a viable therapeutic molecular target for ovarian cancer management.

CD71+ Population Enriched by HPV-E6 Protein Promotes Cancer Aggressiveness and Radioresistance in Cervical Cancer Cells.

A subpopulation of cells within tumors has been suggested to possess the ability to initiate tumorigenesis and contribute to resistance to cancer therapy. Identification and isolation of this subpopulation in cancer cells can be achieved by detecting specific cell-surface markers. In this study, flow cytometry analysis revealed an abundant CD71+ subpopulation in human papillomavirus (HPV)-positive cervical cancer cells, while limited CD71+ cells were detected in HPV-negative cervical cancer cells. Furthermore, ectopic expression of the HPV-E6 protein in HPV-negative C33A cells enriched the CD71+subpopulation. The CD71+ subpopulation isolated from the C33A cell line and an HPV-E6-overexpressing clone exhibited enhanced transforming ability, proliferation, and resistance to irradiation. In contrast, suppression of CD71 in HPV-positive SiHa cells and the HPV-E6-overexpressing stable clone inhibited spheroid formation and in vitro and in vivo tumorigenicity and sensitized cells to irradiation treatment. CRISPR/Cas9 knockout of CD71 in SiHa cells also produced similar inhibitory effects on tumorigenicity. Double knockout of CD71 and CD55 reversed the oncogenic properties of the HPV-E6-overexpressing clone. These findings suggest that the HPV-E6 protein enriches the subpopulation of CD71+cells in cervical cancer, which exhibit cancer stem-like cell properties and are resistant to irradiation treatment. Targeting the CD71+ subpopulation in cervical cancer cells with siRNAs or CRISPR/Cas9 may provide new insights for the development of novel therapeutic approaches for treating cervical cancer. IMPLICATIONS: We describe the enrichment of CD71+ population by HPV-E6 protein in cervical cancer cells that promotes cancer aggressiveness and resistance to irradiation treatment.

Human papillomavirus E6 protein enriches the CD55(+) population in cervical cancer cells, promoting radioresistance and cancer aggressiveness.

Accumulating evidence indicates that the human papillomavirus (HPV) E6 protein plays a crucial role in the development of cervical cancer. Subpopulations of cells that reside within tumours are responsible for tumour resistance to cancer therapy and recurrence. However, the identity of such cells residing in cervical cancer and their relationship with the HPV-E6 protein have not been identified. Here, we isolated sphere-forming cells, which showed self-renewal ability, from primary cervical tumours. Gene expression profiling revealed that cluster of differentiation (CD) 55 was upregulated in primary cervical cancer sphere cells. Flow-cytometric analysis detected abundant CD55(+) populations among a panel of HPV-positive cervical cancer cell lines, whereas few CD55(+) cells were found in HPV-negative cervical cancer and normal cervical epithelial cell lines. The CD55(+) subpopulation isolated from the C33A cell line showed significant sphere-forming ability and enhanced tumourigenicity, cell migration, and radioresistance. In contrast, the suppression of CD55 in HPV-positive CaSki cells inhibited tumourigenicity both in vitro and in vivo, and sensitized cells to radiation treatment. In addition, ectopic expression of the HPV-E6 protein in HPV-negative cervical cancer cells dramatically enriched the CD55(+) subpopulation. CRISPR/Cas9 knockout of CD55 in an HPV-E6-overexpressing stable clone abolished the tumourigenic effects of the HPV-E6 protein. Taken together, our data suggest that HPV-E6 protein expression enriches the CD55(+) population, which contributes to tumourigenicity and radioresistance in cervical cancer cells. Targeting CD55 via CRISPR/Cas9 may represent a novel avenue for developing new strategies and effective therapies for the treatment of cervical cancer. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Hypermethylation of SOX2 Promoter in Endometrial Carcinogenesis.

This paper aimed at investigating the expression and methylation profiles of SOX2, a gene coding for the stem cell-related transcription factor SOX2, in endometrial carcinomas. By methylation-specific polymerase chain reaction (MS-PCR), the methylation status of SOX2 promoter region in 72 endometrial carcinomas and 12 normal endometrial samples was examined. Methylated allele was found in 37.5% (27/72) of endometrial carcinomas but only in 8.3% (1/12) of normal endometrial, significantly more frequent in cancers (P = .0472). SOX2 mRNA level was significantly reduced in endometrial carcinoma compared with nonneoplastic endometrium (P = .045). A significant correlation between SOX2 mRNA expression and hypermethylation of SOX2 was found (P = .024). Hypermethylation of SOX2 tended to be more frequently found in type II serous or clear cell adenocarcinoma. SOX2 methylation was also significantly correlated with shorter survival of patients (P = .046). In conclusion, epigenetic mechanisms may play a crucial role on the transcriptional regulation of SOX2 and loss of SOX2 expression may be related to endometrial carcinogenesis.

Overexpression of the Parkinson disease protein DJ-1 and its regulator PTEN in gestational trophoblastic disease.

DJ-1 is found to be important in human neurodegenerative diseases and cancers by regulating oxidative damage and apoptosis. DJ-1 is also a regulator of PTEN, a frequently mutated tumor suppressor gene in cancers. In this study, we investigated the expression of DJ-1 and PTEN in normal placentas and gestational trophoblastic disease in relation to apoptotic indices and p53 status. A total of 95 trophoblastic samples were retrieved for immunohistochemical study whereas 79 trophoblastic samples, 3 normal trophoblastic and 2 choriocarcinoma cell lines were collected for quantitative real time reverse transcription polymerase chain reaction detection. There was a significant correlation between DJ-1 and PTEN immunostaining indices in the trophoblastic samples (P=0.013). Significantly higher DJ-1 and PTEN immunoreactivity indices were found in the complete mole (P<0.01) and choricarcinoma (P<0.01) compared with the first trimester placenta. Quantitative real time reverse transcription polymerase chain reaction also detected significantly higher messenger ribonucleic acid expressions of DJ-1 and PTEN in hydatidiform moles (P<0.05) and choriocarcinomas (P<0.05) compared with the first trimester placentas. A significant negative correlation was found between DJ-1 and the apoptosis resistant gene Bcl-2 (P=0.031), whereas a positive correlation was shown between PTEN and wild-type p53 (P=0.019). Significant correlations between PTEN and embryonic stem cell transcription factors, Stat3 and Nanog, were also displayed (P=0.001, 0.015). Our findings showed, for the first time, overexpression of DJ-1 at both transcriptional and protein levels in gestational trophoblastic disease. Overexpressed DJ-1 may play a role in regulating apoptotic activities of trophoblasts in relation to PTEN and p53.

P63 expression in gestational trophoblastic disease: correlation with proliferation and apoptotic dynamics.

p63 regulates cell growth and differentiation and contributes to tumorigenesis through its complex isoforms. Gestational trophoblastic disease encompasses a heterogeneous family of lesions with different malignant potential that arise from various trophoblast subpopulations. This study investigated the expression of p63 isoforms in various trophoblastic diseases and correlated with clinical progress, proliferation, and apoptotic activities. 4A4 and anti-p40 antibodies were applied to assess expressions of total and DeltaNp63 isoforms in 20 placentas, 62 hydatidiform moles, 9 choriocarcinomas, 5 placenta site trophoblastic tumors, and 2 epithelioid trophoblastic tumors immunohistochemically. The immunoreactivity of p63 was localized to the nuclei of cytotrophoblast, villous, and chorionic-type intermediate trophoblasts with significant correlation between 2 p63 indices (P<0.001). p63 indices were significantly lower in placentas of advanced gestational age (P<0.001). Hydatidiform moles demonstrated significantly higher p63 indices than normal placentas (P<0.001). Epithelioid trophoblastic tumors displayed the highest p63 indices (45%-80%) whereas immunoreactivity was only focal in choriocarcinoma (0%-5.62%) and was essentially absent in placenta site trophoblastic tumors. There was no significant correlation between p63 indices and subsequent development of trophoblastic neoplasia in hydatidiform moles (P>0.05). Both p63 indices positively correlated with the proliferative index (Ki67) (P<0.05), apoptotic index (M30) (P<0.005), p53 (P<0.005), and p21(WAF1/CIP1) expression (P<0.005). Our results indicate that DeltaNp63, the dominant isoforms expressed in trophoblasts, display heterogeneous expression patterns in relation to trophoblast subtypes. We also demonstrate for the first time the possible role of p63 in the pathogenesis of gestational trophoblastic disease (GTD) through its interaction with p53-dependent proliferation and apoptotic activities.

Hypermethylation of RAS effector related genes and DNA methyltransferase 1 expression in endometrial carcinogenesis.

Epigenetic aberration is known to be important in human carcinogenesis. Promoter methylation status of RAS effector related genes, RASSF1A, RASSF2A, hDAB2IP (m2a and m2b regions) and BLU, was evaluated in 76 endometrial carcinomas and their non-neoplastic endometrial tissue by methylation specific PCR. Hypermethylation of at least one of the 5 genes was detected in 73.7% of carcinomas. There were significant correlations between methylation of hDAB2IP and RASSF1A, RASSF2A (p = 0.042, p = 0.012, respectively). Significantly, more frequent RASSF1A hypermethylation was found in Type I endometrioid carcinomas than Type II carcinomas (p = 0.049). Among endometrioid cancers, significant association between RASSF1A hypermethylation and advanced stage, as well as between methylation of hDAB2IP at m2a region with deep myometrial invasion (p < 0.05) was observed. mRNA expression of RASSF1A, RASSF2A and BLU in endometrial cancer cell lines significantly increased after treatment with the demethylating agent 5-Aza-2'-deoxycytidine supporting the repressive effect of hypermethylation on their transcription. Immunohistochemical study of DNMT1 on eight normal endometrium, 16 hyperplastic endometrium without atypia, 40 atypical complex hyperplasia and 79 endometrial carcinomas showed progressive increase in DNMT1 immunoreactivity from normal endometrium to endometrial hyperplasia and endometrioid carcinomas (p = 0.001). Among carcinomas, distinctly higher DNMT1 expression was observed in Type I endometrioid carcinomas (p < 0.001). DNMT1 immunoreactivity correlated with RASSF1A and RASSF2A methylation (p < 0.05). The data suggested that hypermethylation of RAS related genes, particularly RASSF1A, was involved in endometrial carcinogenesis with possible divergent patterns in different histological types. DNMT1 protein overexpression might contribute to such aberrant DNA hypermethylation of specific tumor suppressor genes in endometrial cancers.