Hypoxia is involved in the reduction of HtrA3 in patients with endometrial hyperplasia and cancer

Exploring the Role of HtrA Family Genes in Cancer: A Systematic Review

PURPOSE

HtrA1, HtrA2, HtrA3 and HtrA4 appear to be involved in the development of pathologies such as cancer. This systematic review reports the results of a literature search performed to compare the expression of HtrA family genes and proteins in cancer versus non-cancer tissues and cell lines, assess relationships between HtrA expression and cancer clinical features in cancer, and analyse the molecular mechanism, by which HtrA family affects cancer.

METHODS

The literature search was conducted according to the PRISMA statement among four databases (PubMed, Web of Science, Embase and Scopus).

RESULTS

A total of 38 articles met the inclusion criteria and involved the expression of HtrA family members and concerned the effect of HtrA expression on cancer and metastasis development or on the factor that influences it. Additionally, 31 reports were retrieved manually. Most articles highlighted that HtrA1 and HtrA3 exhibited tumour suppressor activity, while HtrA2 was associated with tumour growth and metastasis. There were too few studies to clearly define the role of the HtrA4 protease in tumours.

CONCLUSION

Although the expression of serine proteases of the HtrA family was dependent on tumour type, stage and the presence of metastases, most articles indicated that HtrA1 and HtrA3 expression in tumours was downregulated compared with healthy tissue or cell lines. The expression of HtrA2 was completely study dependent. The limited number of studies on HtrA4 expression made it impossible to draw conclusions about differences in expression between healthy and tumour tissue. The conclusions drawn from the study suggest that HtrA1 and HtrA3 act as tumour suppressors.

Deficiency of HtrA3 Attenuates Bleomycin-Induced Pulmonary Fibrosis Via TGF-β1/Smad Signaling Pathway

PURPOSE

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive interstitial lung disease characterized by excessive extracellular matrix deposition. No effective treatments are currently available for IPF. High-temperature requirement A3 (HtrA3) suppresses tumor development by antagonizing transforming growth factor β (TGF-β) signaling; however, little is known about the role of HtrA3 in IPF. This study investigated the role of HtrA3 in IPF and underlying mechanisms.

METHODS

Lung tissues were collected from patients with IPF and mice with bleomycin (BLM)-induced pulmonary fibrosis, and HtrA3 expression was measured in tissue samples. Then, HtrA3 gene knockout mice were treated with BLM to induce pulmonary fibrosis and explore the effects and underlying mechanism of HtrA3 on pulmonary fibrosis.

RESULTS

HtrA3 was up-regulated in the lung tissues of patients with IPF and the pulmonary fibrotic mouse model compared to corresponding control groups. HtrA3 knockout decreased pulmonary fibrosis-related protein expression, alleviated the symptoms of pulmonary fibrosis, and inhibited epithelial-mesenchymal transition (EMT) in BLM-induced lung tissue compared with BLM-induced wild-type mice. The TGF-β1/Smad signaling pathway was activated in fibrotic lung tissue, whereas HtrA3 knockout inhibited this pathway.

CONCLUSION

The expression level of HtrA3 is increased in fibrotic lungs. HtrA3 knockout alleviates the symptoms of pulmonary fibrosis probably via the TGF-β1/Smad signaling pathway. Therefore, HtrA3 inhibition is a potential therapeutic target for pulmonary fibrosis.

Establishment of a prognostic prediction system based on tumor microenvironment of pancreatic cancer

BACKGROUND

Pancreatic cancer (PC) is an inflammatory tumor. Tumor microenvironment (TME) plays an important role in the development of PC. This study aims to explore hub genes of TME and establish a prognostic prediction system for PC.

METHODS

High throughput RNA-sequencing and clinical data of PC were downloaded from The Cancer Genome Atlas and International Cancer Genome Consortium database, respectively. PC patients were divided into high- and low-score group by using stromal, immune scores system based on ESTIMATE. Differentially expressed genes between high- and low-score patients were screened and survival-related differentially expressed genes were identified as candidate genes by univariate Cox regression analysis. Final variables for establishment of the prognostic prediction system were determined by LASSO analysis and multivariate Cox regression analysis. The predictive power of the prognostic system was evaluated by internal and external validation.

RESULTS

A total of 210 candidate genes were identified by stromal, immune scores system, and survival analyses. Finally, the prognostic risk score system was constructed by the following genes: FAM57B, HTRA3, CXCL10, GABRP, SPRR1B, FAM83A, and LY6D. In process of internal validation, Harrell concordance index (C-index) of this prognostic risk score system was 0.73, and the area under the receiver operating characteristic curve value of 1-year, 2-year, and 3-year overall survival period was 0.67, 0.76 and 0.86, respectively. In the external validation set, the survival prediction C-index was 0.71, and the area under the curve was 0.81, 0.72, and 0.78 at 1-year, 2-year, and 3-year, respectively.

CONCLUSION

This prognostic risk score system based on TME demonstrated a good predictive capacity to the prognosis of PC. It may provide information for the treatment strategy and follow-up for patients with PC.

Allosteric inhibition of HTRA1 activity by a conformational lock mechanism to treat age-related macular degeneration

The trimeric serine protease HTRA1 is a genetic risk factor associated with geographic atrophy (GA), a currently untreatable form of age-related macular degeneration. Here, we describe the allosteric inhibition mechanism of HTRA1 by a clinical Fab fragment, currently being evaluated for GA treatment. Using cryo-EM, X-ray crystallography and biochemical assays we identify the exposed LoopA of HTRA1 as the sole Fab epitope, which is approximately 30 Å away from the active site. The cryo-EM structure of the HTRA1:Fab complex in combination with molecular dynamics simulations revealed that Fab binding to LoopA locks HTRA1 in a non-competent conformational state, incapable of supporting catalysis. Moreover, grafting the HTRA1-LoopA epitope onto HTRA2 and HTRA3 transferred the allosteric inhibition mechanism. This suggests a conserved conformational lock mechanism across the HTRA family and a critical role of LoopA for catalysis, which was supported by the reduced activity of HTRA1-3 upon LoopA deletion or perturbation. This study reveals the long-range inhibition mechanism of the clinical Fab and identifies an essential function of the exposed LoopA for activity of HTRA family proteases.

Glucose transporters: Important regulators of endometrial cancer therapy sensitivity

Glucose is of great importance in cancer cellular metabolism. Working together with several glucose transporters (GLUTs), it provides enough energy for biological growth. The main glucose transporters in endometrial cancer (EC) are Class 1 (GLUTs 1–4) and Class 3 (GLUTs 6 and 8), and the overexpression of these GLUTs has been observed. Apart from providing abundant glucose uptake, these highly expressed GLUTs also participate in the activation of many crucial signaling pathways concerning the proliferation, angiogenesis, and metastasis of EC. In addition, overexpressed GLUTs may also cause endometrial cancer cells (ECCs) to be insensitive to hormone therapy or even resistant to radiotherapy and chemoradiotherapy. Therefore, GLUT inhibitors may hopefully become a sensitizer for EC precision-targeted therapies. This review aims to summarize the expression regulation, function, and therapy sensitivity of GLUTs in ECCs, aiming to provide a new clue for better diagnosis and treatment of EC.

Overview of Human HtrA Family Proteases and Their Distinctive Physiological Roles and Unique Involvement in Diseases, Especially Cancer and Pregnancy Complications

The mammalian high temperature requirement A (HtrA) proteins are a family of evolutionarily conserved serine proteases, consisting of four homologs (HtrA1-4) that are involved in many cellular processes such as growth, unfolded protein stress response and programmed cell death. In humans, while HtrA1, 2 and 3 are widely expressed in multiple tissues with variable levels, HtrA4 expression is largely restricted to the placenta with the protein released into maternal circulation during pregnancy. This limited expression sets HtrA4 apart from the rest of the family. All four HtrAs are active proteases, and their specific cellular and physiological roles depend on tissue type. The dysregulation of HtrAs has been implicated in many human diseases such as cancer, arthritis, neurogenerative ailments and reproductive disorders. This review first discusses HtrAs broadly and then focuses on the current knowledge of key molecular characteristics of individual human HtrAs, their similarities and differences and their reported physiological functions. HtrAs in other species are also briefly mentioned in the context of understanding the human HtrAs. It then reviews the distinctive involvement of each HtrA in various human diseases, especially cancer and pregnancy complications. It is noteworthy that HtrA4 expression has not yet been reported in any primary tumour samples, suggesting an unlikely involvement of this HtrA in cancer. Collectively, we accentuate that a better understanding of tissue-specific regulation and distinctive physiological and pathological roles of each HtrA will improve our knowledge of many processes that are critical for human health.

Multi-omics analysis reveals prognostic value of tumor mutation burden in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) was the sixth common malignancies characteristic with highly aggressive in the world. It was well established that tumor mutation burden (TMB) act as indicator of immunotherapeutic responsiveness in various tumors. However, the role of TMB in tumor immune microenvironment (TIME) is still obscure.

METHOD

The mutation data was analyzed by employing "maftools" package. Weighted gene co-expression network analysis (WGCNA) was implemented to determine candidate module and significant genes correlated with TMB value. Differential analysis was performed between different level of TMB subgroups employing R package "limma". Gene ontology (GO) enrichment analysis was implemented with "clusterProfiler", "enrichplot" and "ggplot2" packages. Then risk score signature was developed by systematical bioinformatics analyses. K-M survival curves and receiver operating characteristic (ROC) plot were further analyzed for prognostic validity. To depict comprehensive context of TIME, XCELL, TIMER, QUANTISEQ, MCPcounter, EPIC, CIBERSORT, and CIBERSORT-ABS algorithm were employed. Additionally, the potential role of risk score on immune checkpoint blockade (ICB) immunotherapy was further explored. The quantitative real-time polymerase chain reaction was performed to detect expression of HTRA3.

RESULTS

TMB value was positively correlated with older age, male gender and early T status. A total of 75 intersection genes between TMB-related genes and differentially expressed genes (DEGs) were screened and enriched in extracellular matrix-relevant pathways. Risk score based on three hub genes significantly affected overall survival (OS) time, infiltration of immune cells, and ICB-related hub targets. The prognostic performance of risks score was validated in the external testing group. Risk-clinical nomogram was constructed for clinical application. HTRA3 was demonstrated to be a prognostic factor in HCC in further exploration. Finally, mutation of TP53 was correlated with risk score and do not interfere with risk score-based prognostic prediction.

CONCLUSION

Collectively, a comprehensive analysis of TMB might provide novel insights into mutation-driven mechanism of tumorigenesis further contribute to tailored immunotherapy and prognosis prediction of HCC.

The role of hypoxia in endometrial cancer

Endometrial cancer represents the most frequent neoplasia from the corpus uteri, and comprises the 14th leading cause of death in women worldwide. Risk factors that contribute to the disease include early menarche, late menopause, nulliparity, and menopausal hormone use, as well as hypertension and obesity comorbidities. The clinical effectiveness of chemotherapy is variable, suggesting that novel molecular targeted therapies against specific cellular processes associated with the maintenance of cancer cell survival and therapy resistance urged to ameliorate the rates of success in endometrial cancer treatment. In the course of tumor growth, cancer cells must adapt to decreased oxygen availability in the microenvironment by upregulation of hypoxia-inducible factors, which orchestrate the activation of a transcriptional program leading to cell survival. During this adaptative process, the hypoxic cancer cells may acquire invasive and metastatic properties as well as increased cell proliferation and resistance to chemotherapy, enhanced angiogenesis, vasculogenic mimicry, and maintenance of cancer cell stemness, which contribute to more aggressive cancer phenotypes. Several studies have shown that hypoxia-inducible factor 1 alpha (HIF-1α) protein is aberrantly overexpressed in many solid tumors from breast, prostate, ovarian, bladder, colon, brain, and pancreas. Thus, it has been considered an important therapeutic target. Here, we reviewed the current knowledge of the relevant roles of cellular hypoxia mechanisms and HIF-1α functions in diverse processes associated with endometrial cancer progression. In addition, we also summarize the role of microRNAs in the posttranscriptional regulation of protein-encoding genes involved in the hypoxia response in endometrial cancer. Finally, we pointed out the need for urgent targeted therapies to impair the cellular processes activated by hypoxia in the tumor microenvironment.

Hsa-miR-494-3p attenuates gene HtrA3 transcription to increase inflammatory response in hypoxia/reoxygenation HK2 Cells

The occurrence of cardiac surgery-associated acute kidney injury (CSA-AKI) increases hospital stay and mortality. MicroRNAs has a crucial role in AKI. This objective of the current study is to explore the function of hsa-miR-494-3p in inflammatory response in human kidney tubular epithelial (HK2) cells with hypoxia/reoxygenation. According to KDIGO standard, patients after cardiac surgery with cardiopulmonary bypass were divided into two groups: AKI (n = 10) and non-AKI patients (n = 8). HK2 were raised in the normal and hypoxia/reoxygenation circumstances and mainly treated by overexpression ofmiR-494-3p and HtrA3. The relationship between miR-494-3p and HtrA3 was determined by dual-luciferase reporter assay. Our result showed that Hsa-miR-494-3p was elevated in the serum of patients with CSA-AKI, and also induced in hypoxic reoxygenated HK2 cells. Hsa-miR-494-3p also increased a hypoxia-reoxygenation induced inflammatory response in HK2 cells. Moreover, as a target gene of miR-494-3p, overexpression of HtrA3 downregulated the hypoxia-reoxygenation induced inflammatory response in HK2 cells. Overexpression of hsa-miR-494-3p-induced inflammatory response was inhibited by overexpression of HtrA3. Collectively, we identified that hsa-miR-494-3p, a miRNA induced in both circulation of AKI patients and hypoxia-reoxygenation-treated HK2 cells, enhanced renal inflammation by targeting HtrA3, which may suggest a possible role as a new therapeutic target for CSA-AKI.

HTRA3 Is a Prognostic Biomarker and Associated With Immune Infiltrates in Gastric Cancer

HtrA serine peptidase 3 (HTRA3) participates in multiple signal pathways and plays an important regulatory role in various malignancies; however, its role on prognosis and immune infiltrates in gastric cancer (GC) remains unclear. The study investigated HTRA3 expression in tumor tissues and its association with immune infiltrates, and determined its prognostic roles in GC patients. Patients with GC were collected from the cancer genome atlas (TCGA). We compared the expression of HTRA3 in GC and normal gastric mucosa tissues with Wilcoxon rank sum test. And logistic regression was used to evaluate the relationship between HTRA3 and clinicopathological characters. Gene ontology (GO) term analysis, Gene set enrichment analysis (GSEA), and single-sample Gene Set Enrichment Analysis (ssGSEA) was conducted to explain the enrichmental pathways and functions and quantify the extent of immune cells infiltration for HTRA3. Kaplan-Meier analysis and Cox regression were performed to evaluate the correlation between HTRA3 and survival rates. A nomogram, based on Cox multivariate analysis, was used to predict the impact of HTRA3 on prognosis. High HTRA3 expression was significantly correlated with tumor histological type, histological grade, clinical stage, T stage, and TP53 status (P < 0.05). HTRA3-high GC patients had a lower 10-year progression-free interval [PFI; hazard ratio (HR): 1.46; 95% confidence interval (CI): 1.02–2.08; P = 0.038], disease-specific survival (DSS; HR: 1.65; CI: 1.08–2.52; P = 0.021) and overall survival (OS; HR: 1.59; CI: 1.14–2.22; P = 0.006). Multivariate survival analysis showed that HTRA3 was an independent prognostic marker for PFI (HR: 1.456; CI: 1.021–2.078; P = 0.038), DSS (HR: 1.650; CI: 1.079–2.522; P = 0.021) and OS [hazard ratio (HR): 1.590; 95% confidence interval (CI):1.140–2.219; P = 0.006]. The C-indexes and calibration plots of the nomogram based on multivariate analysis indicated an effective predictive performance for GC patients. GSEA showed that High HTRA3 expression may activate NF-κB pathway, YAP1/WWTR1/TAZ pathway, and TGFβ pathway. There was a negative correlation between the HTRA3 expression and the abundances of adaptive immunocytes (T helper cell 17 cells) and a positive correlation with abundances of innate immunocytes (natural killer cells, macrophages etc.). HTRA3 plays a vital role in GC progression and prognosis and could be a moderate biomarker for prediction for survival after gastrectomy.

Endometrial Cancer Cells Promote M2-Like Macrophage Polarization by Delivering Exosomal miRNA-21 under Hypoxia Condition

Increasing evidence has demonstrated that hypoxia was an aggressive feature in endometrial cancer (EC), which is significantly associated with the tumor grade, lymph node metastasis, and tumor resistance to chemotherapy. However, the relationship between hypoxia and the immune microenvironment in EC is not very clear. Exosomes are small membrane vesicles secreted from a variety of cell types which mediate cell-to-cell communication through transported biomolecules. Here, we investigated whether exosomes can play an immunomodulatory role in intercellular communication between EC cells and macrophages. EC KEL cells were cultured under hypoxia or normoxic condition to collect exosomes. After identification, the exosomes derived from hypoxic or normoxic KEL cells were cultured with the monocyte cell line THP-1 to study the immunoregulation function of KEL cells. The results showed that the total number of exosomes produced by hypoxic KEL cells was significantly higher than that in normoxic condition. In addition, hypoxia markedly stimulated the increase in miRNA-21 expression in the exosomes. After coculture, we found that exosomal miRNA-21 could be horizontally transferred into THP-1 cells. And then, the notably enhanced mRNA expression levels of IL-10 and CD206 in THP-1 cells were observed, suggestive of M2 polarization. To further study the effect of miRNA-21-containing exosomes, we transfected miRNA-21 mimics or inhibitor into THP-1 cells. The results showed that miRNA-21 mimics promoted IL-10 and CD206 mRNA expression levels, and the miRNA-21 inhibitor significantly prevented the alteration induced by intake of hypoxic KEL cell-derived exosomes. In summary, we found that endometrial cancer KEL cells in hypoxic condition promoted monocyte THP-1 cell transformation to M2-like polarization macrophages through delivering exosomal miRNA-21, which may be a potential mechanism of the formation of the immune microenvironment in EC progression.

A Five-Gene Signature Based on Stromal/Immune Scores in the Tumor Microenvironment and Its Clinical Implications for Liver Cancer

Increasing evidence highlights the clinical significance of stromal cells and immune cells in the liver cancer microenvironment. However, reliable prognostic models have not been well established. This study aimed to develop a gene signature for liver cancer based on stromal and immune scores. Using the estimation of stromal and immune cells in malignant tumor tissues using expression data (ESTIMATE) algorithm, stromal and immune scores were estimated based on the transcriptome profile of The Cancer Genome Atlas (TCGA) liver cancer cohort. Stromal-/immune-related differentially expressed genes were identified, followed by functional enrichment analysis. The Cox regression model was used to select prognostic genes and construct a gene signature. Its predictive potential was evaluated by receiver operating characteristic (ROC). The correlation between the risk score and immune cell infiltration was analyzed using Tumor Immune Estimation Resource (TIMER). Three hundred sixty-four upregulated and 10 downregulated stromal-/immune-related genes were identified, were mainly enriched in immune-related processes and pathways. Through univariate and multivariate cox survival analysis, a five-gene risk score was constructed, composed of FABP3, HTRA3, OLFML2B, PDZD4 and SLAMF6. Patients with high score indicated a poorer prognosis than those with low risk score. The areas under the ROC curves of overall survival (OS), progression-free interval, 3-, 5-year, OS status were 0.68, 0.57, 0.72, 0.74 and 0.728, indicating its well performance on predicting patients' prognoses. Furthermore, the risk score and the five genes were significantly correlated with immune cell infiltration in the tumor microenvironment. In this study, we proposed a prognostic five-gene signature based on stromal/immune scores in the liver cancer microenvironment.

Uterine fibroids may play a protecting role against endometrial carcinoma in Chinese women with gynecological diseases

Background: It has been reported that uterine fibroids (UFs) may increase the risk of endometrial carcinoma (EC) with the underlying mechanism largely unknown. Here, we explore whether UF could be an influential factor for EC.

Methods: We have collected and analyzed clinical data from 4537 Chinese patients to study the co-incidence of UF and EC. Then, a large-scale literature-based data mining was conducted to identify genes implicated as UF downstream regulating targets and EC upstream regulators. In addition, a meta-analysis has been conducted for each of the EC-specific genes, using six independent UF expression datasets. The meta-analysis results, together with literature-based pathway analysis, were used to explore the potential explanation of the clinical data.

Results: Our results showed that the incidence rate of EC in the case of UF was 50.53% lower than without UF, which suggested a protective role of UF in EC patients. The meta-analysis identified three significantly overexpressed genes (HTRA3, HOPX, and PCNA) in the case of UF, which were implicated as EC inhibitors in the pathway analysis. Multiple linear regression (MLR) analysis showed that, compared with UF, aging might be a stronger influential factor for EC.

Conclusion: Among women with gynecological diseases, UFs may play a protecting role against EC in the Chinese population.

Identification of a distal allosteric ligand binding pocket in HtrA3

Human HtrA3 (High temperature requirement protease A3) is a trimeric PDZ bearing propapoptotic serine protease, which is involved in various diseases including cancer and pre-eclampsia. Proposed to be a tumor suppressor, its role as a potential therapeutic target is strongly advocated. Therefore, it becomes imperative to gain insights into its mechanism of action and regulation. Allostery is a well-known mechanism of catalytic activation for many HtrA3 homologs, which opens up avenues for manipulating enzyme functions for therapeutic intervention. In our study, through in silico and biochemical approaches, we have reported for the first time that HtrA3 shows allosteric behaviour. We identified a novel selective binding pocket, which triggers conformational reorientations through signal propagation to the distantly situated active-site pocket via the functionally important loop regions. Using molecular docking, simulation studies and biochemical studies we have identified the regulatory movements at and around the active site pocket. Our study is the first one to report a non-classical binding site for HtrA3, which is instrumental for formation of a catalytically efficient orthosteric pocket upon substrate binding.