Expression of hypoxia-inducible factor 1alpha, hypoxia-inducible factor 2alpha, and von Hippel-Lindau protein in epithelial ovarian neoplasms and allelic loss of von Hippel-Lindau gene: nuclear expression of hypoxia-inducible factor 1alpha is an independent prognostic factor in ovarian carcinoma

Characterization of adnexal lesions using photoacoustic imaging to improve sonographic O-RADS risk assessment

OBJECTIVE

To assess the impact of photoacoustic imaging (PAI) on the assessment of ovarian/adnexal lesion(s) of different risk categories using the sonographic ovarian-adnexal imaging-reporting-data system (O-RADS) in women undergoing planned oophorectomy.

METHOD

This prospective study enrolled women with ovarian/adnexal lesion(s) suggestive of malignancy referred for oophorectomy. Participants underwent clinical ultrasound (US) examination followed by coregistered US and PAI prior to oophorectomy. Each ovarian/adnexal lesion was graded by two radiologists using the US O-RADS scale. PAI was used to compute relative total hemoglobin concentration (rHbT) and blood oxygenation saturation (%sO2 ) colormaps in the region of interest. Lesions were categorized by histopathology into malignant ovarian/adnexal lesion, malignant Fallopian tube only and several benign categories, in order to assess the impact of incorporating PAI in the assessment of risk of malignancy with O-RADS. Malignant and benign histologic groups were compared with respect to rHbT and %sO2 and logistic regression models were developed based on tumor marker CA125 alone, US-based O-RADS alone, PAI-based rHbT with %sO2 , and the combination of CA125, O-RADS, rHbT and %sO2. Areas under the receiver-operating-characteristics curve (AUC) were used to compare the diagnostic performance of the models.

RESULTS

There were 93 lesions identified on imaging among 68 women (mean age, 52 (range, 21-79) years). Surgical pathology revealed 14 patients with malignant ovarian/adnexal lesion, two with malignant Fallopian tube only and 52 with benign findings. rHbT was significantly higher in malignant compared with benign lesions. %sO2 was lower in malignant lesions, but the difference was not statistically significant for all benign categories. Feature analysis revealed that rHbT, CA125, O-RADS and %sO2 were the most important predictors of malignancy. Logistic regression models revealed an AUC of 0.789 (95% CI, 0.626-0.953) for CA125 alone, AUC of 0.857 (95% CI, 0.733-0.981) for O-RADS only, AUC of 0.883 (95% CI, 0.760-1) for CA125 and O-RADS and an AUC of 0.900 (95% CI, 0.815-0.985) for rHbT and %sO2 in the prediction of malignancy. A model utilizing all four predictors (CA125, O-RADS, rHbT and %sO2 ) achieved superior performance, with an AUC of 0.970 (95% CI, 0.932-1), sensitivity of 100% and specificity of 82%.

CONCLUSIONS

Incorporating the additional information provided by PAI-derived rHbT and %sO2 improves significantly the performance of US-based O-RADS in the diagnosis of adnexal lesions. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Zinc fingers and homeoboxes 2 inhibition could suppress the proliferation of ovarian cancer cells by apoptosis pathway

OBJECTIVE

The Zinc fingers and homeoboxes (ZHX) protein family has been reported to be involved in tumor development; however, it remains controversial whether these proteins can act as promoters or inhibitors of cancer development. The current study focused on the biological role of ZHX2 in ovarian cancer.

METHODS

Tissue microarrays were established using 154 ovarian cancer samples. Immunohistochemical analysis was employed to determine the expression levels of ZHX2 in ovarian cancer samples. The prognostic analysis was performed using the Kaplan-Meier method and compared with a log-rank test. The specific role of ZHX2 in ovarian cancer was investigated in cell lines in vitro.

RESULTS

It was found that ZHX2 was not significantly overexpressed in ovarian cancer samples; however, its expression was significantly correlated with advanced tumor grade. Patient survival analysis indicated that patients with high expression of ZHX2 exhibited worse overall survival rate compared with those with low expression of ZHX2. Furthermore, univariate and multivariate analyses demonstrated that ZHX2 was an independent prognostic factor of progression-free survival in patients with ovarian cancer. In vitro experiments indicated that inhibition of ZHX2 could significantly suppress ovarian cancer cell proliferation via induction of the apoptotic pathway.

CONCLUSIONS

The data indicated that ZHX2 may be considered a promising biomarker in ovarian cancer and that inhibition of its expression may be a potential therapeutic target in ovarian cancer treatment.

Hypoxia-Related lncRNA Prognostic Model of Ovarian Cancer Based on Big Data Analysis

Background

Hypoxia is regarded as a key factor in promoting the occurrence and development of ovarian cancer. In ovarian cancer, hypoxia promotes cell proliferation, epithelial to mesenchymal transformation, invasion, and metastasis. Long non-coding RNAs (lncRNAs) are extensively involved in the regulation of many cellular mechanisms, i.e., gene expression, cell growth, and cell cycle.

Materials and Methods

In our study, a hypoxia-related lncRNA prediction model was established by applying LASSO-penalized Cox regression analysis in public databases. Patients with ovarian cancer were divided into two groups based on the median risk score. The survival rate was analyzed in the Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) datasets, and the mechanisms were investigated.

Results

Through the prognostic analysis of DElncRNAs (differentially expressed long non-coding RNAs), a total of 5 lncRNAs were found to be closely associated with OS (overall survival) in ovarian cancer patients. It was evaluated through Kaplan-Meier analysis that low-risk patients can live longer than high-risk patients (TCGA: p = 1.302e - 04; ICGC: 1.501e - 03). The distribution of risk scores and OS status revealed that higher risk score will lead to lower OS. It was evaluated that low-risk group had higher immune score (p = 0.0064) and lower stromal score (p = 0.00023).

Conclusion

It was concluded that a hypoxia-related lncRNA model can be used to predict the prognosis of ovarian cancer. Our designed model is more accurate in terms of age, grade, and stage when predicting the overall survival of the patients of ovarian cancer.

Updated perspective of EPAS1 and the role in pulmonary hypertension

Pulmonary hypertension (PH) is a group of syndromes characterized by irreversible vascular remodeling and persistent elevation of pulmonary vascular resistance and pressure, leading to ultimately right heart failure and even death. Current therapeutic strategies mainly focus on symptoms alleviation by stimulating pulmonary vessel dilation. Unfortunately, the mechanism and interventional management of vascular remodeling are still yet unrevealed. Hypoxia plays a central role in the pathogenesis of PH and numerous studies have shown the relationship between PH and hypoxia-inducible factors family. EPAS1, known as hypoxia-inducible factor-2 alpha (HIF-2α), functions as a transcription factor participating in various cellular pathways. However, the detailed mechanism of EPAS1 has not been fully and systematically described. This article exhibited a comprehensive summary of EPAS1 including the molecular structure, biological function and regulatory network in PH and other relevant cardiovascular diseases, and furthermore, provided theoretical reference for the potential novel target for future PH intervention.

Differential Expression of HIF1A, EPAS1, and VEGF Genes in Benign and Malignant Ovarian Neoplasia

Simple Summary

Ovarian cancer (OC) has the highest mortality rate of all gynecological malignancies. Moreover, at the time of the first clinical manifestation, most patients have an advanced stage of the disease. Our study examined differences in mRNA levels of hypoxia-inducible factor 1-alpha (HIF1A); endothelial PAS domain protein 1, also known as hypoxia-inducible factor 2-alpha (HIF2A/EPAS1); and vascular endothelial growth factor A (VEGFA) between cancerous tissue, benign hyperplastic changes in the ovary, and normal tissue. We found that gene expression changes were visible not only in the case-control study, but also along with changes in severity. We observed disturbances in the expression levels of interdependent genes. Our findings suggest that mutual association in the expression of both HIF1A and HIF2A/EPAS1 with VEGFA has prognostic importance for patients with OC. Our observations may help identify patients for clinical trials aimed at inhibiting the hypoxia-induced neovascularization-dependent pathways.

Abstract

Ovarian cancer (OC) has the highest mortality rate of all gynecological malignancies. Moreover, at the time of the first clinical manifestation, most patients have an advanced stage of the disease. Our study examined differences in mRNA levels of hypoxia-inducible factor 1-alpha (HIF1A); endothelial PAS domain protein 1, also known as hypoxia-inducible factor 2-alpha (HIF2A/EPAS1); and vascular endothelial growth factor A (VEGFA) between cancerous tissue, benign hyperplastic changes in the ovary, and normal tissue. Our cohorts consisted of 52 patients diagnosed with OC (n = 55), benign non-cancerous changes (n = 21), and normal tissue samples (n = 38). The mRNA expression level was evaluated using RT-qPCR. We found that gene expression changes were visible not only in the case-control study, but also along with changes in severity. Additionally, the gene expression was differentiated in age, BMI, menopausal status, and the number of comorbidy-related groups. Furthermore, our findings demonstrate that analyzing the correlation between genes is essential. In a case-to-case and case-to-control study, we observed disturbances in the expression levels of interdependent genes. Our findings suggest that mutual association in the expression of both HIF1A and HIF2A/EPAS1 with VEGFA has prognostic importance for patients with OC. Our observations may help identify patients for clinical trials aimed at inhibiting the hypoxia-induced neovascularization-dependent pathways.

USP33 deubiquitinates and stabilizes HIF-2alpha to promote hypoxia response in glioma stem cells

Hypoxia regulates tumor angiogenesis, metabolism, and therapeutic response in malignant cancers including glioblastoma, the most lethal primary brain tumor. The regulation of HIF transcriptional factors by the ubiquitin-proteasome system is critical in the hypoxia response, but hypoxia-inducible deubiquitinases that counteract the ubiquitination remain poorly defined. While the activation of ERK1/2 also plays an important role in hypoxia response, the relationship between ERK1/2 activation and HIF regulation remains elusive. Here, we identified USP33 as essential deubiquitinase that stabilizes HIF-2alpha protein in an ERK1/2-dependent manner to promote hypoxia response in cancer cells. USP33 is preferentially induced in glioma stem cells by hypoxia and interacts with HIF-2alpha, leading to its stabilization through deubiquitination. The activation of ERK1/2 upon hypoxia promoted HIF-2alpha phosphorylation, enhancing its interaction with USP33. Silencing of USP33 disrupted glioma stem cells maintenance, reduced tumor vascularization, and inhibited glioblastoma growth. Our findings highlight USP33 as an essential regulator of hypoxia response in cancer stem cells, indicating a novel potential therapeutic target for brain tumor treatment.

HIF-1α Is a Rational Target for Future Ovarian Cancer Therapies

Ovarian cancer is the eighth most commonly diagnosed cancer among women worldwide. Even with the development of novel drugs, nearly one-half of the patients with ovarian cancer die within five years of diagnosis. These situations indicate the need for novel therapeutic agents for ovarian cancer. Increasing evidence has shown that hypoxia-inducible factor-1α(HIF-1α) plays an important role in promoting malignant cell chemoresistance, tumour metastasis, angiogenesis, immunosuppression and intercellular interactions. The unique microenvironment, crosstalk and/or interaction between cells and other characteristics of ovarian cancer can influence therapeutic efficiency or promote the disease progression. Inhibition of the expression or activity of HIF-1α can directly or indirectly enhance the therapeutic responsiveness of tumour cells. Therefore, it is reasonable to consider HIF-1α as a potential therapeutic target for ovarian cancer. In this paper, we summarize the latest research on the role of HIF-1α and molecules which can inhibit HIF-1α expression directly or indirectly in ovarian cancer, and drug clinical trials about the HIF-1α inhibitors in ovarian cancer or other solid malignant tumours.

Immunomodulatory Effects of Perioperative Dexmedetomidine in Ovarian Cancer: An In Vitro and Xenograft Mouse Model Study

Background

The surgical stress response (SSR) causes immunosuppression which may cause residual tumor growth and micrometastasis after cancer surgery. We investigated whether dexmedetomidine affects cancer cell behavior and immune function in an ovarian cancer xenograft mouse model.

Methods

The effect of dexmedetomidine on cell viability and cell cycle was assessed using SK-OV-3 cells at drug concentrations of 0.5, 0.1, 5, and 10 µg mL^-1. BALB/c nude mice were used for the ovarian cancer model with the Dexmedetomidine group (n=6) undergoing surgery with dexmedetomidine infusion and the Control group (n=6) with saline infusion for 4 weeks. Natural killer (NK) cell activity, serum proinflammatory cytokines, and cortisol were measured at predetermined time points and tumor burden was assessed 4 weeks after surgery.

Results

Dexmedetomidine had no effect on cell viability or cell cycle. Following a sharp decrease on postoperative day (POD) 1, NK cell activity recovered faster in the Dexmedetomidine group with significant difference vs. the Control group on POD 3 (P=0.028). In the Dexmedetomidine group, cortisol levels were lower on POD 3 (P=0.004) and TNF-α levels were lower at 4 weeks after surgery (P<0.001) compared to the Control group. The Dexmedetomidine group showed lower tumor burden at 4 weeks vs. the Control group as observed by both tumor weight (P<0.001) and the in vivo imaging system (P=0.03).

Conclusions

Dexmedetomidine infusion may improve ovarian cancer surgery outcome by suppressing the SSR and stress mediator release. Further studies are needed to elucidate the mechanisms by which dexmedetomidine acts on cancer and immune cells.

Histone deacetylase inhibitor induced pVHL-independent degradation of HIF-1α and hierarchical quality control of pVHL via chaperone system

The mortality rate of ovarian cancer is increasing and the role of hypoxia inducible factor-1α (HIF-1α) in tumor progression has been confirmed. von Hippel-Lindau tumor suppressor protein (pVHL) binds HIF-1α and mediates proteasome degradation of HIF-1α. Besides, histone deacetylase inhibitor (HDACi) mitigates tumor growth via targeting HIF-1α, whereas underlying mechanism still requires investigation. In this research, we exposed ovarian cancer cell lines OV-90 and SKOV-3 to escalating concentrations of HDACi LBH589. As a result, cell viability was significantly suppressed and expression of HIF-1α was remarkably reduced along with decreased levels of signal molecules, including phosphoinositide 3-kinase (PI3K) and glycogen synthase kinase 3β (GSK3β) (P = 0.000). Interestingly, pVHL was expressed in a notably declining tendency (P = 0.000). Chaperone heat shock protein-70 (HSP70) was expressed in an ascending manner, whereas expression of chaperonin TCP-1α was reduced clearly (P = 0.000). Besides, co-inhibition of pVHL plus HDAC did not contribute to a remarkable difference in HIF-1α expression as compared with single HDAC inhibition. Furthermore, both cell lines were transfected with plasmids of VHL plus VHL binding protein-1 (VBP-1). Consequently, the expression of HIF-1α as well as lactate dehydrogenase-A (LDHA) was remarkably decreased (P = 0.000). These findings indicate HDACi may repress expression of HIF-1α via inhibiting PI3K and GSK3β and promote degradation of HIF-1α via HSP70, independent of pVHL. Additionally, a sophisticated network of HDAC and chaperones may involve in pVHL quality control.

Temporal Quantitative Proteomics Reveals Proteomic and Phosphoproteomic Alterations Associated with Adaptive Response to Hypoxia in Melanoma Cells

Simple Summary

Most solid tumours, including melanoma (skin cancer), are riddled with areas lacking adequate oxygen supply due to insufficient vasculature. Cancer cells in these regions are resistant to therapies and contribute to cancer spread and poor treatment response in patients. Understanding the mechanisms by which cancer cells adapt to survive in such a hostile environment will provide novel avenues for treatment. In this study, we investigated mechanisms that melanoma cells use to adapt and survive in an oxygen-poor environment. We used four different melanoma cell lines and studied how protein levels and phosphorylation patterns on thousands of proteins change when the cells are exposed to poor oxygen conditions. This revealed potential mechanisms on which cancer cells are dependent for survival. These survival mechanisms can be potentially targeted to achieve durable response to therapy. We demonstrate this by targeting one such mechanism required for cancer cell survival.

Abstract

Hypoxia is a common feature in various solid tumours, including melanoma. Cancer cells in hypoxic environments are resistant to both chemotherapy and radiation. Hypoxia is also associated with immune suppression. Identification of proteins and pathways that regulate cancer cell survival in hypoxic environments can reveal potential vulnerabilities that can be exploited to improve the efficacy of anticancer therapies. We carried out temporal proteomic and phosphoproteomic profiling in melanoma cell lines to identify hypoxia-induced protein expression and phosphorylation changes. By employing a TMT-based quantitative proteomics strategy, we report the identification and quantitation of >7000 proteins and >10,000 phosphosites in melanoma cell lines grown in hypoxia. Proteomics data show metabolic reprogramming as one of the prominent adaptive responses in hypoxia. We identify several novel hypoxia-mediated phosphorylation changes that have not been reported before. They reveal kinase signalling pathways that are potentially involved in modulating cellular response to hypoxia. In addition to known protein expression changes, we identify several novel proteomic alterations associated with adaptive response to hypoxia. We show that cancer cells require the ubiquitin–proteasome system to survive in both normoxia and hypoxia. Inhibition of proteasome activity affects cell survival and may provide a novel therapeutic avenue to target cancer cells in hypoxia. Our study can serve as a valuable resource to pursue novel candidates to target hypoxia in cancers and improve the efficacy of anticancer therapies.

IL-6 promotes nuclear translocation of HIF-1α to aggravate chemoresistance of ovarian cancer cells

The inflammatory milieu in tumor modulates the resistance to the conventional antitumoral therapies. Interleukin-6 (IL-6), a pleiotropic pro-inflammatory cytokine and a crucial mediator of tumor development, has been targeted as a therapeutic strategy to overcome chemoresistance in the treatment of tumors. The protein levels and nuclear translocation of HIFs (hypoxia-inducible factors), such as HIF-1α, are linked to the drug resistance of tumor cells. However, whether IL-6 promotes the nuclear translocation of HIF-1α and the related mechanism remain to be investigated. We applied two ovarian cancer (OvCa) cell lines, A2780 cells and SKOV3 cells for the in vivo and in vitro studies. We found that IL-6 up-regulates the HIF-1α expression via the signal transducer and activator of transcription 3 (STAT3) signaling under hypoxia in either endogenous or exogenous way, and then we proved that IL-6 enhances the transcriptional activity of HIF-1α via the STAT3 signaling. Further mechanism research revealed that IL-6 promotes the nuclear translocation of HIF-1α through the STAT3 signaling under hypoxia. Proliferation assay and apoptosis assay were applied and proved that IL-6 enhances the chemoresistance of OvCa cells against cisplatin through the upregulation of HIF-1α via the STAT3 signaling in vitro. The In vivo studies confirmed the effect of IL-6 in increasing the chemoresistance of OvCa cells against cisplatin through the IL-6/STAT3/HIF-1α loop in the animal models. Our data elucidates the explicit mechanism of IL-6/STAT3/HIF-1α loop in OvCa and also provides new insights into the development of different approaches for the inflammation-induced and hypoxia-induced resistance in tumor therapies.

Characterizing Endocrine Status, Tumor Hypoxia and Immunogenicity for Therapy Success in Epithelial Ovarian Cancer

Epithelial ovarian cancer is predominantly diagnosed at advanced stages which creates significant therapeutic challenges. As a result, the 5-year survival rate is low. Within ovarian cancer, significant tumor heterogeneity exists, and the tumor microenvironment is diverse. Tumor heterogeneity leads to diversity in therapy response within the tumor, which can lead to resistance or recurrence. Advancements in therapy development and tumor profiling have initiated a shift from a "one-size-fits-all" approach towards precision patient-based therapies. Here, we review aspects of ovarian tumor heterogeneity that facilitate tumorigenesis and contribute to treatment failure. These tumor characteristics should be considered when designing novel therapies or characterizing mechanisms of treatment resistance. Individual patients vary considerably in terms of age, fertility and contraceptive use which innately affects the endocrine milieu in the ovary. Similarly, individual tumors differ significantly in their immune profile, which can impact the efficacy of immunotherapies. Tumor size, presence of malignant ascites and vascular density further alters the tumor microenvironment, creating areas of significant hypoxia that is notorious for increasing tumorigenesis, resistance to standard of care therapies and promoting stemness and metastases. We further expand on strategies aimed at improving oxygenation status in tumors to dampen downstream effects of hypoxia and set the stage for better response to therapy.

Prognostic and Clinicopathological Significance of Hypoxia-Inducible Factor-1α in Endometrial Cancer: A Meta-Analysis

Background

Current reports on the prognostic and predictive value of hypoxia-inducible factor-1α (HIF-1α) in endometrial carcinoma are inconsistent. Therefore, we conducted this meta-analysis to precisely evaluate the association of HIF-1α expression with susceptibility, clinical features, and prognosis of endometrial cancer.

Methods

Eligible studies that assessed the role of HIF-1α protein expression, immunohistochemistry detection, disease susceptibility, clinical features, and prognosis of endometrial cancer were searched from the Embase, Pubmed, and Web of Science databases. Stata 14.0 software was used to merge and compute pooled hazard ratios (HR) and odds ratios (OR). Information including HIF-1α protein expression and clinical progression of endometrial cancer was extracted. The pooled HR and OR with corresponding 95% confidence intervals (CI) were used to estimate the strength of these associations.

Results

A total of 25 studies were included in the analysis. HIF-1α protein expression in endometrial cancer tissue was significantly higher than that in normal tissues (OR = 15.79, 95% CI = 8.44–29.52, P < 0.05). Endometrial cancer patients with higher HIF-1α protein expression had poorer prognosis compared to patients with low HIF-1α protein expression (HR = 2.29, 95% CI = 1.68–2.90, P < 0.05). In addition, high HIF-1α protein expression was significantly associated with endometrial cancer grade, lymph node metastasis, and myometrial invasion (grade in Caucasians: OR = 3.09, 95% CI = 1.63–5.85, P < 0.05; lymph node metastasis: OR = 3.09, 95% CI = 1.63–5.85, P < 0.05; myometrial invasion: OR = 2.26, 95% CI = 2.15–5.08, P < 0.05).

Conclusions

HIF-1α overexpression was significantly associated with increased risk, advanced clinical progression, and poor prognosis in endometrial cancer patients.

The Drug-Resistance Mechanisms of Five Platinum-Based Antitumor Agents

Platinum-based anticancer drugs, including cisplatin, carboplatin, oxaliplatin, nedaplatin, and lobaplatin, are heavily applied in chemotherapy regimens. However, the intrinsic or acquired resistance severely limit the clinical application of platinum-based treatment. The underlying mechanisms are incredibly complicated. Multiple transporters participate in the active transport of platinum-based antitumor agents, and the altered expression level, localization, or activity may severely decrease the cellular platinum accumulation. Detoxification components, which are commonly increasing in resistant tumor cells, can efficiently bind to platinum agents and prevent the formation of platinum–DNA adducts, but the adducts production is the determinant step for the cytotoxicity of platinum-based antitumor agents. Even if adequate adducts have formed, tumor cells still manage to survive through increased DNA repair processes or elevated apoptosis threshold. In addition, autophagy has a profound influence on platinum resistance. This review summarizes the critical participators of platinum resistance mechanisms mentioned above and highlights the most potential therapeutic targets or predicted markers. With a deeper understanding of the underlying resistance mechanisms, new solutions would be produced to extend the clinical application of platinum-based antitumor agents largely.

Ovarian Cancer, Cancer Stem Cells and Current Treatment Strategies: A Potential Role of Magmas in the Current Treatment Methods

Epithelial ovarian cancer (EOC) constitutes 90% of ovarian cancers (OC) and is the eighth most common cause of cancer-related death in women. The cancer histologically and genetically is very complex having a high degree of tumour heterogeneity. The pathogenic variability in OC causes significant impediments in effectively treating patients, resulting in a dismal prognosis. Disease progression is predominantly influenced by the peritoneal tumour microenvironment rather than properties of the tumor and is the major contributor to prognosis. Standard treatment of OC patients consists of debulking surgery, followed by chemotherapy, which in most cases end in recurrent chemoresistant disease. This review discusses the different origins of high-grade serous ovarian cancer (HGSOC), the major sub-type of EOC. Tumour heterogeneity, genetic/epigenetic changes, and cancer stem cells (CSC) in facilitating HGSOC progression and their contribution in the circumvention of therapy treatments are included. Several new treatment strategies are discussed including our preliminary proof of concept study describing the role of mitochondria-associated granulocyte macrophage colony-stimulating factor signaling protein (Magmas) in HGSOC and its unique potential role in chemotherapy-resistant disease.

Dynamic contrast-enhanced perfusion parameters in ovarian cancer: Good accuracy in identifying high HIF-1α expression

BACKGROUND

Hypoxia significantly influences treatment response and clinical outcome in solid tumors. A noninvasive marker for hypoxia will help physicians in treatment planning and encourage the efficient use of hypoxia targeted therapies. The purpose of this study was to investigate whether pharmacokinetic dynamic contrast-enhanced (DCE) perfusion parameters are associated with a specific marker of hypoxia, hypoxia-inducible factor 1 alpha (HIF-1α) in ovarian cancer (OC).

MATERIALS AND METHODS

Thirty-eight patients with primary OC were enrolled in this prospective study approved by the local ethical committee. Patients underwent dynamic gadolinium-enhanced 3.0 T MRI as part of their staging investigations. Pharmacokinetic perfusion parameters, including a rate constant for transfer of contrast agent from plasma to extravascular extracellular space (EES) (Ktrans) and a rate constant from EES to plasma (Kep), were measured by drawing two types of regions of interest (ROIs): a large solid lesion (L-ROI) and a solid, most enhancing small area (S-ROI) (NordicICE platform). Tissue samples for immunohistochemical analysis were collected during surgery. Kruskal-Wallis, Mann-Whitney U and Chi-square tests were used in statistical analyses. Receiver Operating Characteristic curve analyzes were done for DCE parameters to discriminate high HIF-1α expression.

RESULTS

Pharmacokinetic perfusion parameters Ktrans and Kep were inversely associated with HIF-1α expression (Ktrans L-ROI P = 0.021; Ktrans S-ROI P = 0.018 and Kep L-ROI P = 0.032; Kep S-ROI P = 0.033). Ktrans and Kep showed good accuracy in identifying high HIF-1α expression (AUC = 0.832 Ktrans L-ROI; 0.840 Ktrans S-ROI; 0.808 Kep L-ROI and 0.808 Kep L-ROI).

CONCLUSION

This preliminary study demonstrated that pharmacokinetic DCE-MRI perfusion parameters are associated with the hypoxia specific marker, HIF-1α in OC. DCE-MRI may be a useful supplementary tool in the characterization of OC tumors in a staging investigation.

A GPX4-dependent cancer cell state underlies the clear-cell morphology and confers sensitivity to ferroptosis

Clear-cell carcinomas (CCCs) are a histological group of highly aggressive malignancies commonly originating in the kidney and ovary. CCCs are distinguished by aberrant lipid and glycogen accumulation and are refractory to a broad range of anti-cancer therapies. Here we identify an intrinsic vulnerability to ferroptosis associated with the unique metabolic state in CCCs. This vulnerability transcends lineage and genetic landscape, and can be exploited by inhibiting glutathione peroxidase 4 (GPX4) with small-molecules. Using CRISPR screening and lipidomic profiling, we identify the hypoxia-inducible factor (HIF) pathway as a driver of this vulnerability. In renal CCCs, HIF-2α selectively enriches polyunsaturated lipids, the rate-limiting substrates for lipid peroxidation, by activating the expression of hypoxia-inducible, lipid droplet-associated protein (HILPDA). Our study suggests targeting GPX4 as a therapeutic opportunity in CCCs, and highlights that therapeutic approaches can be identified on the basis of cell states manifested by morphological and metabolic features in hard-to-treat cancers.

Clear-cell carcinomas are aggressive tumours characterised by high accumulation of lipids and glycogen. Here, the authors report that these cancers have a common vulnerability to GPX4 inhibition-induced ferroptosis and using CRISPR screen and lipodomic profiling, they identify HIF-2α- HILPDA axis promotes ferroptosis via enrichment of PUFA lipids.

Genome-Wide Interrogation of Human Cancers Identifies EGLN1 Dependency in Clear Cell Ovarian Cancers

We hypothesized that candidate dependencies for which there are small molecules that are either approved or in advanced development for a nononcology indication may represent potential therapeutic targets. To test this hypothesis, we performed genome-scale loss-of-function screens in hundreds of cancer cell lines. We found that knockout of EGLN1, which encodes prolyl hydroxylase domain-containing protein 2 (PHD2), reduced the proliferation of a subset of clear cell ovarian cancer cell lines in vitro. EGLN1-dependent cells exhibited sensitivity to the pan-EGLN inhibitor FG-4592. The response to FG-4592 was reversed by deletion of HIF1A, demonstrating that EGLN1 dependency was related to negative regulation of HIF1A. We also found that ovarian clear cell tumors susceptible to both genetic and pharmacologic inhibition of EGLN1 required intact HIF1A. Collectively, these observations identify EGLN1 as a cancer target with therapeutic potential. SIGNIFICANCE: These findings reveal a differential dependency of clear cell ovarian cancers on EGLN1, thus identifying EGLN1 as a potential therapeutic target in clear cell ovarian cancer patients.

Collagen Remodeling in the Hypoxic Tumor-Mesothelial Niche Promotes Ovarian Cancer Metastasis

Peritoneal metastases are the leading cause of morbidity and mortality in high-grade serous ovarian cancer (HGSOC). Accumulating evidence suggests that mesothelial cells are an important component of the metastatic microenvironment in HGSOC. However, the mechanisms by which mesothelial cells promote metastasis are unclear. Here, we report that the HGSOC tumor-mesothelial niche was hypoxic, and hypoxic signaling enhanced collagen I deposition by mesothelial cells. Specifically, hypoxic signaling increased expression of lysyl oxidase (LOX) in mesothelial and ovarian cancer cells to promote collagen crosslinking and tumor cell invasion. The mesothelial niche was enriched with fibrillar collagen in human and murine omental metastases. Pharmacologic inhibition of LOX reduced tumor burden and collagen remodeling in murine omental metastases. These findings highlight an important role for hypoxia and mesothelial cells in the modification of the extracellular matrix and tumor invasion in HGSOC. SIGNIFICANCE: This study identifies HIF/LOX signaling as a potential therapeutic target to inhibit collagen remodeling and tumor progression in HGSOC.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/9/2271/F1.large.jpg.

Association of the hypoxia-inducible factor-1α (HIF-1α) gene polymorphisms with prognosis in ovarian clear cell carcinoma

Background

Ovarian clear cell carcinoma (OCCC) is the second most common ovarian cancer after serous carcinoma in Japan. OCCC has a more unfavorable clinical outcome due to a poor response to platinum-based chemotherapy, compared with serous carcinoma. Hypoxia inducible factor-1α (HIF-1α) is a key regulator of cellular response to hypoxia and plays an important role in tumor growth, and HIF-1α gene single-nucleotide polymorphisms (SNPs) adversely affect the outcome in some cancers. Herein, we investigated the association of the HIF-1α gene SPNs with clinical outcome in OCCCs. Eighty-nine patients with OCCC were recruited in whom pathological diagnosis was confirmed with surgically resected specimen.

Results

The SNPs of C1772T and G1790A in the HIF-1α gene occurred in 23.6 and 3.3% of the patients, respectively. In the univariate analysis, overall survival was associated with stage and surgical residual tumor but not with the SNPs C1772T, G1790A, C1772T and/or G1790A. In the multivariate survival analysis, a significant association was observed between outcome and FIGO stage and/or surgical residual tumor; however, no association was obtained between HIF-1α gene SNPs and these factors.

Conclusion

In conclusion, unlike the other cancers in which HIF-1α gene SNPs were demonstrated to be associated with the outcome, OCCC prognosis may not be affected by HIF-1α gene SNPs. Further studies need to be performed to clarify the association of HIF-1α expression with the unfavorable prognosis in OCCCs, in terms of transcriptional/translational activity, nuclear translocation of the protein, and protein degradation.

Prognostic Role of Hypoxia-Inducible Factor-2α Tumor Cell Expression in Cancer Patients: A Meta-Analysis

Hypoxia-inducible factor-2α (HIF-2α) plays an important role in tumor progression and metastasis. A number of studies have evaluated the correlation between HIF-2α overexpression and clinical outcome in cancer patients but yielded inconsistent results. To comprehensively and quantitatively summarize the evidence on the capability of HIF-2α to predict the prognosis of cancer patients with solid tumors, a meta-analysis was carried out. Renal cell carcinoma (CC-RCC) was separately analyzed due to an alternative mechanism of regulation. Systematic literature searches were performed in PubMed and Embase databases for relevant original articles until February 2018. Forty-nine studies with 6,052 patients were included in this study. The pooled hazard ratios (HRs) with corresponding confidence intervals were calculated to assess the prognostic value of HIF-2α protein expression in tumor cells. The meta-analysis revealed strong significant negative associations between HIF-2α expression and five endpoints: overall survival [HR = 1.69, 95% confidence interval (95% CI) 1.39-2.06], disease-free survival (HR = 1.87, 95% CI 1.2-2.92), disease-specific survival (HR = 1.57, 95% CI 1.06-2.34), metastasis-free survival (HR = 2.67, 95% CI 1.32-5.38), and progression-free survival (HR = 2.18, 95% CI 1.25-3.78). Subgroup analyses revealed similar associations in the majority of tumor sites. Overall, these data demonstrate a negative prognostic role of HIF-2α in patients suffering from different types of solid tumors.

ΔNp73 enhances HIF-1α protein stability through repression of the ECV complex

Cellular responses to low oxygen conditions are mainly regulated by the Hypoxia-inducible factors (HIFs). Induction of HIF-1α in tumor cells activates the angiogenic switch and allows for metabolic adaptations. HIF-1α protein levels are tightly regulated through ubiquitin-mediated proteosomal degradation; however, high levels of HIF-1α is a common feature in many solid tumors and is thought to enhance cancer cell proliferation, migration, and survival. Here, we report that the oncogenic p73 isoform, ∆Np73, increases HIF-1α protein stability. We found that ∆Np73 represses expression of genes encoding subunits of the ECV complex, in particular Elongin C, Elongin B, Cullin 2, and Rbx1. The ECV complex is an E3 ligase complex responsible for polyubiquitinating HIF-1α. Loss of ∆Np73 increases ubiquitination of HIF-1α, leading to its degradation via the proteosomal pathway, and subsequent decrease of HIF-1α target genes. Taken together, our data demonstrates that high levels of ∆Np73 stabilize HIF-1α protein, allowing for it to accumulate and further potentiating its transcriptional activity and supporting tumor progression.

Hypoxia-inducible factor 1 alpha is required for the tumourigenic and aggressive phenotype associated with Rab25 expression in ovarian cancer

The small GTPase Rab25 has been functionally linked to tumour progression and aggressiveness in ovarian cancer and promotes invasion in three-dimensional environments. This type of migration has been shown to require the expression of the hypoxia-inducible factor 1 alpha (HIF-1α). In this report we demonstrate that Rab25 regulates HIF-1α protein expression in an oxygen independent manner in a panel of cancer cell lines. Regulation of HIF-1α protein expression by Rab25 did not require transcriptional upregulation, but was dependent on de novo protein synthesis through the Erbb2/ERK1/2 and p70S6K/mTOR pathways. Rab25 expression induced HIF-1 transcriptional activity, increased cisplatin resistance, and conferred intraperitoneal growth to the A2780 cell line in immunocompromised mice. Targeting HIF1 activity by silencing HIF-1β re-sensitised cells to cisplatin in vitro and reduced tumour formation of A2780-Rab25 expressing cells in vivo in a mouse ovarian peritoneal carcinomatosis model. Similar effects on cisplatin resistance in vitro and intraperitoneal tumourigenesis in vivo were obtained after HIF1b knockdown in the ovarian cancer cell line SKOV3, which expresses endogenous Rab25 and HIF-1α at atmospheric oxygen concentrations. Our results suggest that Rab25 tumourigenic potential and chemoresistance relies on HIF1 activity in aggressive and metastatic ovarian cancer. Targeting HIF-1 activity may potentially be effective either alone or in combination with standard chemotherapy for aggressive metastatic ovarian cancer.

Protective effects of Paeoniflorin against AOPP-induced oxidative injury in HUVECs by blocking the ROS-HIF-1α/VEGF pathway

BACKGROUND

Paeoniflorin, a monoterpene glycoside, exerts protective vascular effects, showing good antioxidant properties. However, whether Paeoniflorin has protective effect against the oxidative damage induced by advanced oxidation protein products (AOPPs) in Human umbilical vein endothelial cells (HUVECs) is unknown, as is the underlying mechanism.

PURPOSE

The present study was designed to investigate the effect of Paeoniflorin on oxidative damage of HUVECs and elucidate its underlying molecular mechanisms.

METHODS

The fluorescence intensity of 2', 7'-dichlorofluorescein-diacetate (DCFH-DA) staining was detected for intracellular reactive oxygen species (ROS) production. The increases mitochondrial membrane potential (MMP) was measured via flow cytometry and confocal microscopy using MitoTracker® Deep Red/ MitoTracker® Green staining. The intracellular adenosine triphosphate (ATP) was measured by ATP Determination Kit according to the manufacturer's protocol. Nox2, Nox4, hypoxia inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) and nuclear factor-κB (NF-κB) p65 expressions were detected by western blot.

RESULTS

Our results showed that Paeoniflorin increases MMP and ATP levels of HUVECs induced by AOPPs, and attenuates NF-κB p65 expression on HUVECs might mainly result from its antioxidant capability by suppressing ROS production. Moreover, we also found that Paeoniflorin can suppress HIF-1α and VEGF protein expression through a decrease of ROS production via down-regulation of Nox2/Nox4 expression in HUVECs. AOPP-induced RAGE mRNA up-regulation was blocked by Paeoniflorin treatment in HUVECs.

CONCLUSION

Our results provided the first experimental that Paeoniflorin protects against AOPP-induced oxidative damage in HUVECs, mainly through a mechanism involving a decrease in ROS production by the inhibition of Nox2/Nox4 and RAGE expression; restored ATP depletion and mitochondria dysfunction via ROS suppression; and down-regulated HIF-1α/VEGF, possibly via the ROS-NF-κB axis.

Hypoxic pathobiology of breast cancer metastasis

Dissemination of breast cancer cells (BCCs) to distant sites (metastasis) is the ultimate cause of mortality in patients with breast cancer. Hypoxia (low O₂) is a microenvironmental hallmark of most solid cancers arising as a mismatch between cellular O₂ consumption and supply. Hypoxic selection of BCCs triggers molecular and cellular adaptations dependent upon hypoxia-inducible factors (HIFs), a family of evolutionarily conserved transcriptional activators that coordinate the expression of numerous genes controlling each step of the metastatic process. In this review, we summarize current advances in the understanding of HIF-driven molecular mechanisms that promote BCC metastatic dissemination and patient mortality. In addition, we discuss the clinical and therapeutic implications of HIF targeting in breast cancers.

Potential Coagulation Factor-Driven Pro-Inflammatory Responses in Ovarian Cancer Tissues Associated with Insufficient O₂ and Plasma Supply

Tissue factor (TF) is a cell surface receptor for coagulation factor VII (fVII). The TF-activated fVII (fVIIa) complex is an essential initiator of the extrinsic blood coagulation process. Interactions between cancer cells and immune cells via coagulation factors and adhesion molecules can promote progression of cancer, including epithelial ovarian cancer (EOC). This process is not necessarily advantageous, as tumor tissues generally undergo hypoxia due to aberrant vasculature, followed by reduced access to plasma components such as coagulation factors. However, hypoxia can activate TF expression. Expression of fVII, intercellular adhesion molecule-1 (ICAM-1), and multiple pro-inflammatory cytokines can be synergistically induced in EOC cells in response to hypoxia along with serum deprivation. Thus, pro-inflammatory responses associated with the TF-fVIIa-ICAM-1 interaction are expected within hypoxic tissues. Tumor tissue consists of multiple components such as stromal cells, interstitial fluid, albumin, and other micro-factors such as proton and metal ions. These factors, together with metabolism reprogramming in response to hypoxia and followed by functional modification of TF, may contribute to coagulation factor-driven inflammatory responses in EOC tissues. The aim of this review was to describe potential coagulation factor-driven inflammatory responses in hypoxic EOC tissues. Arguments were extended to clinical issues targeting this characteristic tumor environment.

Molecular targeting of hypoxia in radiotherapy

Hypoxia (low O₂) is an essential microenvironmental driver of phenotypic diversity in human solid cancers. Hypoxic cancer cells hijack evolutionarily conserved, O₂- sensitive pathways eliciting molecular adaptations that impact responses to radiotherapy, tumor recurrence and patient survival. In this review, we summarize the radiobiological, genetic, epigenetic and metabolic mechanisms orchestrating oncogenic responses to hypoxia. In addition, we outline emerging hypoxia- targeting strategies that hold promise for individualized cancer therapy in the context of radiotherapy and drug delivery.

The role of hypoxia-inducible factors in tumor angiogenesis and cell metabolism

Hypoxia-inducible factor (HIF) is a main heterodimeric transcription factor that regulates the cellular adaptive response to hypoxia by stimulating the transcription of a series of hypoxia-inducible genes. HIF is frequently upregulated in solid tumors, and the overexpression of HIF can promote tumor progression or aggressiveness by blood vessel architecture and altering cellular metabolism. In this review, we focused on the pivotal role of HIF in tumor angiogenesis and energy metabolism. Furthermore, we also emphasized the possibility of HIF pathway as a potential therapeutic target in cancer.

Expression of HIF-1α and HIF-2α correlates to biological and clinical significance in papillary thyroid carcinoma

BACKGROUND

The aim of this study was to detect the expression of hypoxia-inducible factor (HIF)-1α and HIF-2α in papillary thyroid carcinoma (PTC) compared with normal thyroid tissues.

METHODS

The mRNA levels and protein levels of HIF-1α and HIF-2α were detected by real-time PCR and Western blot separately in 30 pairs of PTCs and normal thyroid cases. The protein levels were also detected by immunohistochemistry (IHC) using 92 samples of PTC group and 46 normal samples as control group for analyzing the biological and clinical significance of the expression of HIF-1α/HIF-2α.

RESULTS

Real-time PCR results showed the mRNA level of HIF-1α and HIF-2α were significantly higher in PTC than normal group (P<0.001). Also, significantly higher positive rates (73%/65%) of HIF-1α and HIF-2α were observed in PTC compared with the control group (27%/35%) by IHC (P<0.01); the consistent results were gotten with Western blot. Although we did not find a significant correlation between the expression of HIF-1α and HIF-2α with gender, age, calcification, or Hashimoto's disease in the present study (P>0.05), both of their expressions were correlated to lymph node metastasis (P<0.05), capsular invasion (P<0.05), and TNM stage (P<0.05).

CONCLUSIONS

Overexpression of HIF-1α and HIF-2α are associated with the carcinogenesis of PTC, served as potential biomarkers of PTC.

4.1N suppresses hypoxia-induced epithelial-mesenchymal transition in epithelial ovarian cancer cells

Protein 4.1N (4.1N) is a member of the protein 4.1 family and is essential for the regulation of cell adhesion, motility and signaling. Previous studies have suggested that 4.1N may serve a tumor suppressor role. However, the molecular mechanisms remain unclear. In the current study, the role of 4.1N in the downregulation of hypoxia‑induced factor 1α (HIF‑1α) under hypoxic conditions and therefore the suppression of hypoxia induced epithelial‑mesenchymal transition (EMT) was investigated. The data were obtained from overexpressed and knockdown 4.1N epithelial ovarian cancer (EOC) cell lines. It was identified that 4.1N was capable of regulating the sub‑cellular localization and expression levels of HIF‑1α, by which 4.1N served a dominant role in the suppression of hypoxia‑induced EMT and associated genes. Collectively, the data of the current study identified 4.1N as an inhibitor of hypoxia‑induced tumor progression in EOC cells and highlighted its potential role in EOC therapy.

Peritumoral Neuropilin-1 and VEGF receptor-2 expression increases time to recurrence in hepatocellular carcinoma patients undergoing curative hepatectomy

PURPOSE

To determined Neuropilin-1 (NRP-1) and vascular endothelial growth factor receptor 2 (VEGFR-2) expression in the tumoral and peritumoral tissues of 214 treatment-naïve HCC patients and its correlation with overall survival (OS) and time to recurrence (TTR).

EXPERIMENTAL DESIGN

NRP-1 and VEGFR-2 expression were examined by tissue microarray and peritumoral hypoxia by pimonidazole staining and angiogenesis by microvessel density (MVD). OS and TTR were evaluated by Kaplan-Meier analysis and log-rank test.

RESULTS

Peritumoral NRP-1 and VEGFR-2 expression were significantly higher than that of the tumoral tissue (p < 0.001 for both), and high peritumoral expression of both factors was negatively associated with tumor size (p < 0.001 for both). Patients with high peritumoral expression of both proteins had the longest median OS (>94.0 months) and TTR (>84.0 months). The multivariate Cox proportional hazards analysis revealed that patients with high peritumoral expression of both NRP-1 and VEGFR-2 were more than 4 times less likely to have recurrence (p = 0.004) and more than 10 times likely to survive (p < 0.001).

CONCLUSIONS

Peritumoral NRP-1 and VEGFR-2 expression is associated with prolonged TTR and extended OS of HCC patients and both may be useful as predictors of surgical outcome of HCC patients and explored as potential therapeutic targets.

Clinicopathological characteristics of gynecological cancer associated with hypoxia-inducible factor 1α expression: a meta-analysis including 6,612 subjects

BACKGROUND

Gynecological cancer is characterized by tumor hypoxia. However, the role of hypoxia-inducible factor 1α (HIF-1α) in gynecological cancer remains unclear.

METHOD

Electronic databases including Cochrane Library, PUBMED, Web of Knowledge and clinical trial registries were searched from inception through October 2014 for published, case-control studies assessing the association between HIF-1α and the clinicopathological characteristics of gynecological cancer. We pooled results from 59 studies using fixed or random-effects models and present results as odds ratios (ORs) following the PRISMA guidelines.

RESULTS

Our meta-analysis, which included 6,612 women, demonstrated that the expression of HIF-1α was associated with the clinicopathological characteristics of gynecological cancer. The expression of HIF-1α in cancer or borderline tissue was significantly higher than that in normal tissue (cancer vs. normal: odds ratio (OR) =9.59, 95% confidence interval (CI): 5.97, 15.39, p<0.00001; borderline vs. normal: OR=4.13, 95% (CI): 2.43, 7.02, p<0.00001; cancer vs. borderline: OR=2.70, 95% (CI): 1.69, 4.31, p<0.0001). The expression of HIF-1α in III-IV stage or lymph node metastasis was significantly higher than that in I-II stage or that without lymph node metastasis, respectively (OR=2.66, 95% (CI): 1.87,3.79, p<0.00001; OR= 3.98, 95% (CI): 2.10,12.89, p<0.0001). HIF-1α was associated with histological grade of cancer (Grade 3 vs. Grade 1: OR=3.77, 95% (CI): 2.76,5.16, p<0.00001; Grade 3 vs. Grade 2: OR=1.62, 95% (CI): 1.20,2.19, p=0.002; Grade 2 vs. Grade 1: OR=2.34, 95% (CI): 1.82,3.00, p<0.00001),5-years disease free survival (DFS) rates (OR=2.93, 95% (CI):1.43,6.01, p=0.001) and 5-years overall survival (OS) rates (OR=5.53, 95% (CI): 2.48,12.31, p<0.0001).

CONCLUSION

HIF-1α is associated with the malignant degree, FIGO stage, histological grade, lymph node metastasis, 5-years survival rate and recurrence rate of gynecological cancer. It may play an important role in clinical treatment and prognostic evaluation.

HIF1α is an independent prognostic factor for overall survival in advanced primary epithelial ovarian cancer - a study of the OVCAD Consortium

PURPOSE

Hypoxia is a common phenomenon encountered in solid cancers, leading to chemotherapy resistance and therefore to aggressiveness of the disease. The homeostatic response to hypoxia is mediated by hypoxiainducible factor-1 (HIF-1). The aim of this study was to investigate the impact of HIF1α in patients with primary epithelial ovarian cancer.

METHODS

In this multicentric study, 275 patients with advanced primary epithelial ovarian cancer were included. All patients underwent cytoreductive surgery with maximal surgical effort and adjuvant platinum-based chemotherapy. HIF1α expression was analyzed in tissue lysates, using an enzyme-linked immunosorbent assay.

RESULTS

HIF1α was detected in 79.3% of the tissue samples. Patients with increased HIF1α expression (cutoff: 80 pg/mg protein) in tumoral tissue lysates were more likely to have less favorable survival. HIF1α (P=0.009, hazard ratio [HR] 2.505, 95% confidence interval [95% CI] 1.252-5.013) together with International Federation of Gynecology and Obstetrics (III versus IV) (P=0.013, HR 0.540, 95% CI 0.332-0.878), histology (P=0.007, HR 2.748, 95% CI 1.315-5.743), presence of peritoneal carcinomatosis (P=0.014, HR 2.176, 95% CI 1.170-4.046), residual tumor mass (P=0.017, HR 1.641, 95% CI 1.091-2.468), and response to platinum-based chemotherapy (P<0.001, HR 8.131, 95% CI 5.13-12.88) were independent prognosis factors for overall survival. The independent prognostic factors for progression-free survival were International Federation of Gynecology and Obstetrics stage (P=0.01), histological subtypes (P=0.016), and presence of peritoneal carcinomatosis (P<0.05).

CONCLUSION

HIF1α overexpression in ovarian cancer is associated with poor overall survival, underlining the importance of hypoxia in this angiogenesis driven disease.

Hypoxia-induced miR-210 in epithelial ovarian cancer enhances cancer cell viability via promoting proliferation and inhibiting apoptosis

miR-210 is upregulated in a HIF-1α-dependent way in several types of cancers. In addition, upregulated miR-210 promotes cancer proliferation, via its anti-apoptotic effects. It is blind to the regulation of miR-210 under hypoxia conditions for ovarian cancer cells and to the effect of miR-210 on ovarian cancer growth. In the present study, we determined the expression of miR-210 in epithelial ovarian cancer specimens, and in ovarian cancer cell lines under hypoxia conditions, and determined in detail the effect of miR-210 overexpression on tumor cell proliferation, and the possible mechanisms of tumor growth by miR-210 regulation. It was shown that miR-210 expression is upregulated, in response to hypoxia conditions in epithelial ovarian cancer specimens as well as epithelial ovarian cancer cell lines, with an association to HIF-1α overexpression. Furthermore, upregulated miR-210 promoted tumor growth in vitro via targeting PTPN1 and inhibiting apoptosis. Therefore, our findings shed light on the mechanism of ovarian cancer adaptation to hypoxia.

Prognostic role of hypoxic inducible factor expression in non-small cell lung cancer: a meta-analysis

INTRODUCTION

Reported prognostic roles of hypoxic inducible factor (HIF) expression in non-small cell lung cancer (NSCLC) have varied. This meta-analysis aimed to examine the relationship between HIF expression and clinical outcome in NSCLC patients.

METHODS

PubMed were used to identify relevant literature with the last report up to December 20th, 2012. After careful review, survival data were collected from eligible studies. We completed the meta-analysis using Stata statistical software (Version 11) and combined hazard ratio (HR) for overall survival (OS). Subgroup specificity, heterogeneity and publication bias were also assessed. All of the results were verified by two persons to ensure accuracy.

RESULTS

Eight studies were finally stepped into this meta-analysis in which seven had available data for HIF-1α and three for HIF-2α. Combined HRs suggested that higher expression of HIF1α had a negative impact on NSCLC patient survival (HR=1.50; 95%CI =1.07-2.10; p=0.019). The expression of HIF-2α was also relative to a poorer survival (HR=2.02; 95%CI =1.47-2.77; p=0.000). No bias existed in either of the two groups.

CONCLUSION

This study suggests that elevations of HIF-1α and HIF- 2α expression are both associated with poor outcome for patients with NSCLC. The data support further and high quality investigation of HIF expression for predicting poor outcome in patients with NSCLC.

Inactivation of von Hippel-Lindau increases ovarian cancer cell aggressiveness through the HIF1α/miR-210/VMP1 signaling pathway

The inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene not only results in tumor initiation, but also mediates tumor metastasis. However, the mechanisms by which VHL inactivation leads to metastasis have not yet been well defined. In this study, the silencing of VHL in 3AO and SKOV3 ovarian cancer cells was found to promote cell motility and to increase the expression of matrix metalloproteinase (MMP)2, MMP9, hypoxia-inducible factor 1-α (HIF-1α) and microRNA (miR)-210. The suppression of HIF-1α with its inhibitor 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1) in VHL-silenced 3AO cells antagonized the pro-migratory activity induced by the VHL deficiency and reversed the upregulation of MMP2, MMP9, HIF-1α and miR-210; however, it had no obvious effect on the VHL protein level. The introduction of miR-210 inhibitor into VHL-silenced 3AO cells resulted in similar changes as those induced by YC-1. Furthermore, vacuole membrane protein 1 (VMP1) was found to be diminished by VHL silencing in a HIF-1α/miR-210-dependent manner. Taken together, our data demonstrate that the loss of VHL stimulates ovarian cancer cell migration by stabilizing HIF-1α, upregulating miR-210 and decreasing VMP1 expression. These results indicate that the aberrant signaling of the VHL/HIF-1α/miR-210/VMP1 pathway may be involved in ovarian cancer aggressiveness.

Hypoxia-related gene expression profile in childhood acute lymphoblastic leukemia: prognostic implications

A cellular hypoxic condition is a key event in several human cancers, but knowledge about its role in childhood acute lymphoblastic leukemia (ALL) is very limited. In the present study, the gene expression profile of hypoxia-related genes (HIF1A, CA9, VEGF and SCL2A1) was evaluated in bone marrow samples of 113 pediatric patients. HIF1A mRNA up-regulation was significantly associated with higher 5-year event-free survival rates in patients with B-ALL as well as in the overall ALL population in both univariate and multivariate analysis (p = 0.023 and p = 0.041, respectively). In gene expression analysis, low oxygen levels promoted HIF1A activation in a time-dependent manner, in both ALL cell lines. In vitro cytotoxic assays suggested an initial trend toward hypoxia-related resistance in the first 24 h, but evaluation at later time points (48-72 h) clearly showed that there was no relevant difference in drug response when comparing hypoxic and normal oxygen level conditions. Modulation of mRNA expression of several hypoxia-related genes was also observed after hypoxic exposure in a cell specific manner, suggesting that HIF1A mRNA expression could play a different role in specific subtypes of leukemia. Despite the remaining questions regarding hypoxia-mediated mechanisms, these findings could be helpful to provide new insights into the role of hypoxia in childhood ALL.

HE4 (WFDC2) gene overexpression promotes ovarian tumor growth

Selective overexpression of Human epididymal secretory protein E4 (HE4) points to a role in ovarian cancer tumorigenesis but little is known about the role the HE4 gene or the gene product plays. Here we show that elevated HE4 serum levels correlate with chemoresistance and decreased survival rates in EOC patients. HE4 overexpression promoted xenograft tumor growth and chemoresistance against cisplatin in an animal model resulting in reduced survival rates. HE4 displayed responses to tumor microenvironment constituents and presented increased expression as well as nuclear translocation upon EGF, VEGF and Insulin treatment and nucleolar localization with Insulin treatment. HE4 interacts with EGFR, IGF1R, and transcription factor HIF1α. Constructs of antisense phosphorothio-oligonucleotides targeting HE4 arrested tumor growth in nude mice. Collectively these findings implicate increased HE4 expression as a molecular factor in ovarian cancer tumorigenesis. Selective targeting directed towards the HE4 protein demonstrates therapeutic benefits for the treatment of ovarian cancer.

Expression of hypoxia-inducible factor-1α and vascular density in mammary adenomas and adenocarcinomas in bitches

Background

The study aimed at examining hypoxia-inducible factor (HIF)1α expression in adenocarcinomas and adenomas in bitches in regard to tumour malignancy grade, proliferation, apoptosis and vascularisation. Therefore, paraffin sections of 15 adenomas and 64 adenocarcinomas sampled from 79 dogs aged 6 to 16 years were analysed.

Results

A significantly higher HIF-1α expression was noted in adenocarcinomas in comparison to adenomas (P < 0.0004). Moreover, HIF-1α expression in adenocarcinomas correlated positively with tumour malignancy grade (r = 0.59, P < 0.05), Ki-67 antigen expression (r = 0.43; P < 0.0005), TUNEL-positive cells (r = 0.62, P < 0001) and tumour vascularity measured by quantification of vessels characterized by the expression of von Willebrand Factor (r = 0.57, P < 0.05).

Conclusion

Results of this study indicate a similar biological role of HIF-1α in dogs and in humans, which may confirm suitability of the animal model in investigations on progression of tumours in humans.

Alterations of Hypoxia-Induced Factor Signaling Pathway Due to Mammalian Target of Rapamycin (mTOR) Suppression in Ovarian Clear Cell Adenocarcinoma: In Vivo and in Vitro Explorations for Clinical Trial

Objectives

Before setting into the clinical trial using a combination of mammalian target of rapamycin (mTOR) inhibitors (rapamycin and everolimus) and other anticancer drugs, this study was conducted to confirm the efficacy of the new therapeutic strategy for ovarian clear cell adenocarcinoma (CCA), which targeted mTOR–hypoxia-induced factor (HIF) signal transduction system.

Materials and Methods

Using the cultured cells of CCA and animal models, alteration of mTOR-HIF cofactors and cell proliferation under the mTOR inhibitor–treated condition were analyzed.

Results

Mammalian target of rapamycin–HIF cofactors were inhibited dependent on concentration by mTOR inhibitor, resulting in suppression of the cultured CCA proliferation. However, von Hippel-Lindau was up-regulated at the messenger RNA level. In the nude mice with subcutaneously implanted CCA cells, apoptosis and necrosis were detected especially around the center of the tumors in the mTOR inhibitor–treated group more conspicuously than in the nontreated group. In the assessment of combination therapy with other antitumor agents, a combined treatment with mTOR inhibitor and chemotherapeutic agents caused a significant decrease in tumor size compared to the chemotherapeutic agents–only group.

Conclusions

Treatment by mTOR inhibitor is expected to down-regulate the cell proliferation of the CCA as a new therapeutic strategy.

Oxygen sensing, hypoxia-inducible factors, and disease pathophysiology

Hypoxia-inducible factors (HIFs) are transcriptional activators that function as master regulators of oxygen homeostasis, which is disrupted in disorders affecting the circulatory system and in cancer. The role of HIFs in these diseases has been elucidated by clinical studies and by analyses of mouse models. HIFs play a protective role in the pathophysiology of myocardial ischemia due to coronary artery disease, limb ischemia due to peripheral arterial disease, pressure-overload heart failure, wound healing, and chronic rejection of organ transplants. In contrast, HIFs contribute to the pathogenesis of pulmonary arterial hypertension, systemic hypertension associated with sleep apnea, ocular neovascularization, hereditary erythrocytosis, and cancer.

Overexpression of CD147 in ovarian cancer is initiated by the hypoxic microenvironment

Ovarian cancer is a lethal malignant tumour characterised by activated invasion, distant metastasis, anti-cancer drug resistance, angiogenesis and metabolism. CD147, an extracellular matrix metalloproteinase inducer, is overexpressed in most ovarian tumours and plays an important role in the progression of ovarian cancer and other malignant tumours. However, the factor(s) initiating this overexpression is unknown. Because of rapid reproduction and their hypoxic microenvironment, malignant tumours use glycolysis for energy, and lactic acid produced is harmful to the cells. For survival, excessive lactate needs to be transported by monocarboxylate transporters (MCTs). Functioning of MCT1 and MCT4 require the ancillary of CD147. The gene for CD147 possesses two hypoxia-inducible factors binding sites in its 3'-flank. It is logical to postulate that the hypoxic microenvironment is a major initiator of the overexpression of CD147, thus conferring on ovarian cancers their malignant properties. A model that can represent spontaneous ovarian cancer is necessary to verify this hypothesis.

The biological kinship of hypoxia with CSC and EMT and their relationship with deregulated expression of miRNAs and tumor aggressiveness

Hypoxia is one of the fundamental biological phenomena that are intricately associated with the development and aggressiveness of a variety of solid tumors. Hypoxia-inducible factors (HIF) function as a master transcription factor, which regulates hypoxia responsive genes and has been recognized to play critical roles in tumor invasion, metastasis, and chemo-radiation resistance, and contributes to increased cell proliferation, survival, angiogenesis and metastasis. Therefore, tumor hypoxia with deregulated expression of HIF and its biological consequence lead to poor prognosis of patients diagnosed with solid tumors, resulting in higher mortality, suggesting that understanding of the molecular relationship of hypoxia with other cellular features of tumor aggressiveness would be invaluable for developing newer targeted therapy for solid tumors. It has been well recognized that cancer stem cells (CSCs) and epithelial-to-mesenchymal transition (EMT) phenotypic cells are associated with therapeutic resistance and contribute to aggressive tumor growth, invasion, metastasis and believed to be the cause of tumor recurrence. Interestingly, hypoxia and HIF signaling pathway are known to play an important role in the regulation and sustenance of CSCs and EMT phenotype. However, the molecular relationship between HIF signaling pathway with the biology of CSCs and EMT remains unclear although NF-κB, PI3K/Akt/mTOR, Notch, Wnt/β-catenin, and Hedgehog signaling pathways have been recognized as important regulators of CSCs and EMT. In this article, we will discuss the state of our knowledge on the role of HIF-hypoxia signaling pathway and its kinship with CSCs and EMT within the tumor microenvironment. We will also discuss the potential role of hypoxia-induced microRNAs (miRNAs) in tumor development and aggressiveness, and finally discuss the potential effects of nutraceuticals on the biology of CSCs and EMT in the context of tumor hypoxia.

Hypoxia-inducible factor 1 alpha mediates epidermal growth factor-induced down-regulation of E-cadherin expression and cell invasion in human ovarian cancer cells

Hypoxia-inducible factor 1α (HIF-1α) regulates the transcription of a number of genes under hypoxia and other extracellular stimulations. It has been shown that E-cadherin is down-regulated by epidermal growth factor receptor (EGF) stimulation, and that cells with low E-cadherin expression are more invasive. Our recent study demonstrated a novel mechanism by which EGF down-regulates E-cadherin expression through production of hydrogen peroxide (H(2)O(2)) and the activation of p38 MAPK in human ovarian cancer cells. In this study, we were interested in examining the potential role of HIF-1α in cell invasion under normoxic conditions, specifically when cells are treated with EGF, which is known to down-regulate E-cadherin and increase invasiveness. We show that EGF treatment induces HIF-1α expression in two human ovarian cancer cell lines (SKOV3 and OVCAR5), and that this effect is diminished by treatment with a membrane-permeable H(2)O(2) scavenger, PEG-catalase. However, the induction of HIF-1α by EGF did not require the activation of p38 MAPK. Treatment with siRNA targeting HIF-1α reduces both basal and EGF-induced HIF-1α levels. Importantly, treatment with HIF-1α siRNA diminishes the up-regulation of Snail and Slug as well as the down-regulation of E-cadherin by EGF. The involvement of HIF-1α in the down-regulation of E-cadherin was confirmed with cobalt chloride (CoCl(2)), a hypoxia-mimetic reagent. Finally, we also show that EGF-induced cell invasion is attenuated by treatment with HIF-1α siRNA. This study demonstrates an important role for HIF-1α in mediating the effects of EGF on Snail, Slug and E-cadherin expression as well as invasiveness in human ovarian cancer cells.

Aberrant expression of the mammalian target of rapamycin, hypoxia-inducible factor-1α, and glucose transporter 1 in the development of ovarian clear-cell adenocarcinoma

Ovarian clear-cell adenocarcinoma (CCA) is known to be a type of cancer in humans with a high frequency of expression of the mammalian target of rapamycin (mTOR), hypoxia-inducible factor-1 (HIF-1), and glucose transporter 1 (Glut1). In this study, we aimed to determine how these alterations contribute to tumor development of CCAs. Immunohistochemical expressions of phosphorylated-mTOR (p-mTOR), HIF-1α, and Glut1 were analyzed in 36 CCAs and 60 coexistent putative precursor lesions: 19 nonatypical and 16 atypical endometriotic lesions, and 11 benign and 14 borderline clear-cell adenofibroma (CCAF) components. Twenty-one cases with solitary endometriosis were also examined. The frequencies of immunopositivity for p-mTOR (in cytoplasm or nucleus), HIF-1α (in nucleus), and Glut1 increased in accordance with higher cytological atypia in the putative precursors: 58%, 5%, and 16% in the nonatypical endometriosis; 63%, 37%, and 50% in the atypical endometriosis; 77%, 95%, and 95% in the endometriosis-associated CCAs; 27%, 0%, and 0% in the benign-CCAF components; 64%, 79%, and 43% in the borderline CCAF components; and 71%, 100%, and 93% in the CCAF-associated CCAs, respectively. p-mTOR, HIF-1α (in the nucleus), and Glut1 were positive in 10%, 5%, and 19% of the solitary endometriosis, respectively. In the putative precursor lesions coexisting with CCA, a strong correlation in the expression between p-mTOR and HIF-1α and between HIF-1α and Glut1 was identified. Expressions of p-mTOR, HIF-1α, and Glut1 have already been evident in the putative precursor lesions of CCA, and these alterations cumulatively occur in the development of ovarian CCA.

Inhibition of the Rho/ROCK pathway enhances the efficacy of cisplatin through the blockage of hypoxia-inducible factor-1α in human ovarian cancer cells

Rho, a Ras-related small GTPase, and Rho-associated coiled coil-containing protein kinase (Rho kinase, ROCK1 and ROCK2) are key regulators of focal adhesion, actomyosin contraction, and thus cell motility. Rho/ROCK kinases also play roles in proliferation, differentiation, apoptosis and oncogenic transformation. In the present study, we have shown that Rho/ROCK pathway inhibition by fasudil, an orally administered inhibitor of Rho kinases, enhanced cisplatin-induced growth inhibition and apoptosis in human ovarian cancer cell lines. Fasudil inhibited hypoxia inducible factor (HIF)-1α protein expression. Knockdown of RhoA, ROCK1 or ROCK2 also attenuated the expression of HIF-1α. Furthermore, knockdown of HIF-1α using small interfering RNA enhanced cisplatin-induced growth inhibition and apoptosis as did inhibition of the Rho/ROCK pathway by fasudil, the Rho/ROCK inhibitor Y27632, or by Rho/ROCK knockdown. Therefore, the Rho/ROCK pathway may modulate HIF-1α signal transduction and blockade of Rho/ROCK enhances the efficacy of cisplatin by inhibiting HIF-1α in ovarian cancer cells. Our findings suggested that the Rho/ROCK pathway may be a new target for molecular targeting therapies against ovarian cancer.