Role of discoidin domain receptor 2 (DDR2) and microRNA-182 in survival of women with high-grade serous ovarian cancer

Strategies for data normalization and missing data imputation and consequences for potential diagnostic microRNA biomarkers in epithelial ovarian cancer

MicroRNAs (miRNAs) are small non-coding RNA molecules regulating gene expression with diagnostic potential in different diseases, including epithelial ovarian carcinomas (EOC). As only a few studies have been published on the identification of stable endogenous miRNA in EOC, there is no consensus which miRNAs should be used aiming standardization. Currently, U6-snRNA is widely adopted as a normalization control in RT-qPCR when investigating miRNAs in EOC; despite its variable expression across cancers being reported. Therefore, our goal was to compare different missing data and normalization approaches to investigate their impact on the choice of stable endogenous controls and subsequent survival analysis while performing expression analysis of miRNAs by RT-qPCR in most frequent subtype of EOC: high-grade serous carcinoma (HGSC). 40 miRNAs were included based on their potential as stable endogenous controls or as biomarkers in EOC. Following RNA extraction from formalin-fixed paraffin embedded tissues from 63 HGSC patients, RT-qPCR was performed with a custom panel covering 40 target miRNAs and 8 controls. The raw data was analyzed by applying various strategies regarding choosing stable endogenous controls (geNorm, BestKeeper, NormFinder, the comparative ΔCt method and RefFinder), missing data (single/multiple imputation), and normalization (endogenous miRNA controls, U6-snRNA or global mean). Based on our study, we propose hsa-miR-23a-3p and hsa-miR-193a-5p, but not U6-snRNA as endogenous controls in HGSC patients. Our findings are validated in two external cohorts retrieved from the NCBI Gene Expression Omnibus database. We present that the outcome of stability analysis depends on the histological composition of the cohort, and it might suggest unique pattern of miRNA stability profiles for each subtype of EOC. Moreover, our data demonstrates the challenge of miRNA data analysis by presenting various outcomes from normalization and missing data imputation strategies on survival analysis.

Discoidin Domain Receptor 2: A New Target in Cancer

BACKGROUND

Discoidin domain receptor is a new and unique type of receptor tyrosine kinases, which binds to collagen, the main compose of an extracellular matrix. DDR1 was identified to mediate cell aggregation, and dysregulation of DDR2 has also been shown to be involved in tumor pathogenesis, although its role in cancer development and progression remains controversial.

SUMMARY

Abnormal expression and mutations of DDR2 have been reported in several cancer types and its participation in different aspects of tumor progression, including proliferation, migration, invasion, metastasis, epithelial-mesenchymal transition, and chemotherapy resistance. Moreover, novel DDR2 inhibitors have been designed and indicate a therapeutic effect for the cancer treatment. Key Messages: In this review, we summarize the current knowledge on the role of DDR2 in cancer promotion and the potential therapeutic value of targeting DDR2.

Transcriptomic analysis of patient plasma reveals circulating miR200c as a potential biomarker for high-grade serous ovarian cancer

Background

High-grade serous tubo-ovarian cancer (HGSC) is the most common histological subtype of epithelial ovarian cancer, and highly lethal. Currently there is no effective screening test and prognosis is poor as the majority of cases are diagnosed at the advanced stage. Cell free RNAs including microRNAs (miRNAs) are dysregulated in ovarian cancer tissue and are detectable in the circulation. This study aimed to determine whether circulating cell free miRNAs may be potential biomarkers for the detection of HGSC.

Methods

Plasma was collected from women with HGSC (Grade 3, n = 24), and benign ovarian masses (n = 24). RNA was extracted from patient plasma and subjected to miRNA targeted next generation sequencing (NGS). A subsequent validation cohort was assessed using plasma collected from women with HGSC (n = 14) and controls (with a benign ovarian mass; n = 15). RNA was extracted and assessed using quantitative RT-PCR.

Results

Differential gene expression (DGE) of the NGS data revealed a significant increase in the miRNA, miR200c, in the circulation of women with HGSC (p less than 0.05) compared to controls. In the validation cohort miR200c expression by qPCR was found to also be increased in the circulation of women with HGSC compared to controls (p = 0.0023).

Conclusions

Circulating miR200c may be a promising candidate biomarker for the detection of HGSC. Further larger cohort studies exploring earlier stages are needed to determine whether circulating miR200c may be a sensitive and specific biomarker of tubo-ovarian cancer.

Recent Advances in the Role of Discoidin Domain Receptor Tyrosine Kinase 1 and Discoidin Domain Receptor Tyrosine Kinase 2 in Breast and Ovarian Cancer

Discoidin domain receptor tyrosine kinases (DDRs) are a class of receptor tyrosine kinases (RTKs), and their dysregulation is associated with multiple diseases (including cancer, chronic inflammatory conditions, and fibrosis). The DDR family members (DDR1a-e and DDR2) are widely expressed, with predominant expression of DDR1 in epithelial cells and DDR2 in mesenchymal cells. Structurally, DDRs consist of three regions (an extracellular ligand binding domain, a transmembrane domain, and an intracellular region containing a kinase domain), with their kinase activity induced by receptor-specific ligand binding. Collagen binding to DDRs stimulates DDR phosphorylation activating kinase activity, signaling to MAPK, integrin, TGF-β, insulin receptor, and Notch signaling pathways. Abnormal DDR expression is detected in a range of solid tumors (including breast, ovarian, cervical liver, gastric, colorectal, lung, and brain). During tumorigenesis, abnormal activation of DDRs leads to invasion and metastasis, via dysregulation of cell adhesion, migration, proliferation, secretion of cytokines, and extracellular matrix remodeling. Differential expression or mutation of DDRs correlates with pathological classification, clinical characteristics, treatment response, and prognosis. Here, we discuss the discovery, structural characteristics, organizational distribution, and DDR-dependent signaling. Importantly, we highlight the key role of DDRs in the development and progression of breast and ovarian cancer.

Prognostic and Clinicopathologic Significance of Discoidin Domain Receptors in Different Human Malignancies: A Meta-Analysis

Background

Discoidin domain receptors (DDRs) belong to the receptor tyrosine kinases family and are activated by different types of collagens, which play roles in various physiological processes. An abnormal expression of DDRs is reported in different types of cancers. Despite many reports about the association and roles of high DDR expression levels in cancers, the prognostic values of DDRs are still unclear. This meta-analysis was performed to evaluate the prognostic effect of DDRs in different tissue cancers.

Method

A literature search was performed in several related databases to find eligible English articles. Based on our research, 20 appropriate studies with 2,602 patients were selected till October 5, 2020. The pooled hazard ratio (HR) with a corresponding 95% confidence interval (CI) was computed to evaluate the strength of correlation between DDRs and survival of cancer patients.

Result

Pooling results showed that a high DDR expression was significantly associated with poorer overall survival (OS) (HR = 1.304, 95% CI 1.007-1.69, p = 0.04). Subgroup analysis based on cancer type revealed a significant link between a high DDR expression level and poor OS both in gastrointestinal (pooled HR = 1.78, 95% CI 1.214-2.624, p = 0.003) and urological cancers (pooled HR = 1.42, 95% CI 1.062-1.82, p = 0.018).

Conclusion

Our meta-analysis results suggest that high DDRs expression has the potential to be used as a biomarker of poor prognosis in cancers.

MicroRNAs as Biomarkers for Early Diagnosis, Prognosis, and Therapeutic Targeting of Ovarian Cancer

Ovarian cancer is the major cause of gynecologic cancer-related mortality. Regardless of outstanding advances, which have been made for improving the prognosis, diagnosis, and treatment of ovarian cancer, the majority of the patients will die of the disease. Late-stage diagnosis and the occurrence of recurrent cancer after treatment are the most important causes of the high mortality rate observed in ovarian cancer patients. Unraveling the molecular mechanisms involved in the pathogenesis of ovarian cancer may help find new biomarkers and therapeutic targets for ovarian cancer. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression, mostly at the posttranscriptional stage, through binding to mRNA targets and inducing translational repression or degradation of target via the RNA-induced silencing complex. Over the last two decades, the role of miRNAs in the pathogenesis of various human cancers, including ovarian cancer, has been documented in multiple studies. Consequently, these small RNAs could be considered as reliable markers for prognosis and early diagnosis. Furthermore, given the function of miRNAs in various cellular pathways, including cell survival and differentiation, targeting miRNAs could be an interesting approach for the treatment of human cancers. Here, we review our current understanding of the most updated role of the important dysregulation of miRNAs and their roles in the progression and metastasis of ovarian cancer. Furthermore, we meticulously discuss the significance of miRNAs as prognostic and diagnostic markers. Lastly, we mention the opportunities and the efforts made for targeting ovarian cancer through inhibition and/or stimulation of the miRNAs.

Discoidin Domain Receptor 2 Mediates Lysophosphatidic Acid-Induced Ovarian Cancer Aggressiveness

Lysophosphatidic acid (LPA), a bioactive lipid produced extracellularly by autotaxin (ATX), has been known to induce various pathophysiological events, including cancer cell invasion and metastasis. Discoidin domain receptor 2 (DDR2) expression is upregulated in ovarian cancer tissues, and is closely associated with poor clinical outcomes in ovarian cancer patients. In the present study, we determined a critical role and signaling cascade for the expression of DDR2 in LPA-induced ovarian cancer cell invasion. We also found ectopic expression of ATX or stimulation of ovarian cancer cells with LPA-induced DDR2 expression. However, the silencing of DDR2 expression significantly inhibited ATX- and LPA-induced ovarian cancer cell invasion. In addition, treatment of the cells with pharmacological inhibitors of phosphoinositide 3-kinase (PI3K), Akt, and mTOR abrogated LPA-induced DDR2 expression. Moreover, we observed that HIF-1α, located downstream of the mTOR, is implicated in LPA-induced DDR2 expression and ovarian cancer cell invasion. Finally, we provide evidence that LPA-induced HIF-1α expression mediates Twist1 expression to upregulate DDR2 expression. Collectively, the present study demonstrates that ATX, and thereby LPA, induces DDR2 expression through the activation of the PI3K/Akt/mTOR/HIF-1α/Twist1 signaling axes, aggravating ovarian cancer cell invasion.

Research Progress in Prognostic Factors and Biomarkers of Ovarian Cancer

Ovarian cancer is a serious threat to women's health; its early diagnosis rate is low and prone to metastasis and recurrence. The current conventional treatment for ovarian cancer is a combination of platinum and paclitaxel chemotherapy based on surgery. The recurrence and progression of ovarian cancer with poor prognosis is a major challenge in treatment. With rapid advances in technology, understanding of the molecular pathways involved in ovarian cancer recurrence and progression has increased, biomarker-guided treatment options can greatly improve the prognosis of patients. This review systematically discusses and summarizes existing and new information on prognostic factors and biomarkers of ovarian cancer, which is expected to improve the clinical management of patients and lead to effective personalized treatment.

Revisiting chemoresistance in ovarian cancer: Mechanism, biomarkers, and precision medicine

Among the gynecological cancers, ovarian cancer is the most lethal. Its therapeutic options include a combination of chemotherapy with platinum-based compounds and cytoreductive surgery. Most ovarian cancer patients exhibit an initial response to platinum-based therapy, however, platinum resistance has led to up to 80% of this responsive cohort becoming refractory. Ovarian cancer recurrence and drug resistance to current chemotherapeutic options is a global challenge. Chemo-resistance is a complex phenomenon that involves multiple genes and signal transduction pathways. Therefore, it is important to elucidate on the underlying molecular mechanisms involved in chemo-resistance. This inform decisions regarding therapeutic management and help in the identification of novel and effective drug targets. Studies have documented the individual biomarkers of platinum-resistance in ovarian cancer that are potential therapeutic targets. This review summarizes the molecular mechanisms of platinum resistance in ovarian cancer, novel drug targets, and clinical outcomes.

miR-519 regulates the proliferation of breast cancer cells via targeting human antigen R

Breast cancer is one of the most prevalent types of cancer among women that leads to millions of deaths worldwide every year. The mechanisms of breast cancer pathogenesis remain unclear. It has been reported that aberrant expression of miR-519, is associated with breast cancer development; however, the effects of miR-519 on breast cancer cell proliferation remain unknown. Therefore, the present study aimed to determine whether miR-519 could regulate breast cancer cell proliferation. A total of 20 pairs of primary breast cancer and adjacent normal tissues were collected from patients with breast cancer. miR-519 expression level was determined by reverse transcription-quantitative polymerase chain reaction. Furthermore, miR-519 mimics or inhibitors were transfected into breast cancer MCF-7 cells in order to up- or downregulate miR-519 expression. Subsequently, human antigen R (HUR), BCL-2 and BAX protein levels were analyzed by western blotting. MCF-7 cell proliferation was assessed using MTT and colony formation assays. A luciferase assay was performed to verify whether miR-519 could directly bind to HUR mRNA. The results demonstrated that miR-519 expression level was lower in primary breast cancer tissues compared with adjacent normal tissues. Furthermore, miR-519 overexpression and downregulation inhibited and stimulated MCF-7 cell proliferation, respectively. In addition, the results from luciferase assay demonstrated that HUR was a target of miR-519. HUR overexpression could reverse the effect of miR-519 mimics on MCF-7 cell proliferation, whereas HUR silencing could rescue the effect of miR-519 inhibitors on MCF-7 cell proliferation. These findings suggested that miR-519 may regulate MCF-7 cell proliferation by targeting HUR.