Roflumilast enhances cisplatin-sensitivity and reverses cisplatin-resistance of ovarian cancer cells via cAMP/PKA/CREB-FtMt signalling axis

cAMP-PKA/EPAC signaling and cancer: the interplay in tumor microenvironment

Cancer is a complex disease resulting from abnormal cell growth that is induced by a number of genetic and environmental factors. The tumor microenvironment (TME), which involves extracellular matrix, cancer-associated fibroblasts (CAF), tumor-infiltrating immune cells and angiogenesis, plays a critical role in tumor progression. Cyclic adenosine monophosphate (cAMP) is a second messenger that has pleiotropic effects on the TME. The downstream effectors of cAMP include cAMP-dependent protein kinase (PKA), exchange protein activated by cAMP (EPAC) and ion channels. While cAMP can activate PKA or EPAC and promote cancer cell growth, it can also inhibit cell proliferation and survival in context- and cancer type-dependent manner. Tumor-associated stromal cells, such as CAF and immune cells, can release cytokines and growth factors that either stimulate or inhibit cAMP production within the TME. Recent studies have shown that targeting cAMP signaling in the TME has therapeutic benefits in cancer. Small-molecule agents that inhibit adenylate cyclase and PKA have been shown to inhibit tumor growth. In addition, cAMP-elevating agents, such as forskolin, can not only induce cancer cell death, but also directly inhibit cell proliferation in some cancer types. In this review, we summarize current understanding of cAMP signaling in cancer biology and immunology and discuss the basis for its context-dependent dual role in oncogenesis. Understanding the precise mechanisms by which cAMP and the TME interact in cancer will be critical for the development of effective therapies. Future studies aimed at investigating the cAMP-cancer axis and its regulation in the TME may provide new insights into the underlying mechanisms of tumorigenesis and lead to the development of novel therapeutic strategies.

A contrast set mining based approach for cancer subtype analysis

The task of detecting common and unique characteristics among different cancer subtypes is an important focus of research that aims to improve personalized therapies. Unlike current approaches mainly based on predictive techniques, our study aims to improve the knowledge about the molecular mechanisms that descriptively led to cancer, thus not requiring previous knowledge to be validated. Here, we propose an approach based on contrast set mining to capture high-order relationships in cancer transcriptomic data. In this way, we were able to extract valuable insights from several cancer subtypes in the form of highly specific genetic relationships related to functional pathways affected by the disease. To this end, we have divided several cancer gene expression databases by the subtype associated with each sample to detect which gene groups are related to each cancer subtype. To demonstrate the potential and usefulness of the proposed approach we have extensively analysed RNA-Seq gene expression data from breast, kidney, and colon cancer subtypes. The possible role of the obtained genetic relationships was further evaluated through extensive literature research, while its prognosis was assessed via survival analysis, finding gene expression patterns related to survival in various cancer subtypes. Some gene associations were described in the literature as potential cancer biomarkers while other results have been not described yet and could be a starting point for future research.

A novel view of ferritin in cancer

Since its discovery more than 85 years ago, ferritin has principally been known as an iron storage protein. However, new roles, beyond iron storage, are being uncovered. Novel processes involving ferritin such as ferritinophagy and ferroptosis and as a cellular iron delivery protein not only expand our thinking on the range of contributions of this protein but present an opportunity to target these pathways in cancers. The key question we focus on within this review is whether ferritin modulation represents a useful approach for treating cancers. We discussed novel functions and processes of this protein in cancers. We are not limiting this review to cell intrinsic modulation of ferritin in cancers, but also focus on its utility in the trojan horse approach in cancer therapeutics. The novel functions of ferritin as discussed herein realize the multiple roles of ferritin in cell biology that can be probed for therapeutic opportunities and further research.

Toosendanin reduces cisplatin resistance in ovarian cancer through modulating the miR-195/ERK/β-catenin pathway

BACKGROUND

Cisplatin (DDP) resistance is prevalent in ovarian cancer (OC) patients and contributes to the poor prognosis. Therefore, it is of great significance to develop new agent to intervene and even reverse DDP resistance in OC. Toosendanin (TSN), a triterpenoid extracted from the bark or fruits of Melia toosendan Sieb et Zucc, has been proved to possess significant antitumor activities. However, the efficacy of TSN on DDP resistance in OC has not been reported yet.

PURPOSE

The aim of this study is to investigate the effects of TSN on DDP resistance in OC and explore the molecular mechanism in vitro and in vivo.

METHODS

Human OC cell line (SKOV3) and DDP-resistant cell line (SKOV3/DDP) were used. Cell proliferation was measured by CCK-8 and colony formation assay. Annexin V/PI double staining and hoechst 33342 nuclear staining were employed to detect cell apoptosis. Transwell and wound-healing assay were used to determine the invasion and migration potential of cells respectively. Quantitative real-time PCR (qPCR) and western blotting were performed to detect the expression of molecules related to miR-195/ERK/β-catenin pathway. The effects and mechanism of TSN on DDP resistance of OC in vivo was investigated using xenograft model, TUNEL staining assay and immunohistochemistry.

RESULTS

TSN improved the DDP sensitivity of SKOV3/DDP cells in vitro and in vivo, reflected in promoting inhibition of proliferation, invasion, migration and epithelial mesenchymal transformation (EMT) as well as induction of apoptosis by DDP. TSN could modulate the miR-195/ERK/β-catenin axis by upregulating the miR-195-5p expression and then suppressing ERK/GSK3β/β-catenin pathway which were activated in SKOV3/DDP cells. Moreover, co-treatment of β-catenin pathway activator LiCl or miR-195-5p silencing partially recovered the DDP resistance which was previously repressed by TSN.

CONCLUSION

Both in vitro and in vivo data demonstrated that TSN could reduce DDP resistance in OC through regulating the miR-195/ERK/β-catenin pathway, highlighting the potential of TSN as an effective agent for favoring overcoming clinical DDP resistance in OC.

Anlotinib induces apoptosis and second growth/mitosis phase block in cisplatin-resistant ovarian cancer cells via the aurora kinase A/p53 pathway

BACKGROUND

Cisplatin (DDP) resistance in ovarian cancer (OC) patients usually leads to treatment failure and increased mortality. Anlotinib has been shown to improve progression-free survival and overall survival in patients with platinum-resistant ovarian cancer, but the mechanism is unclear. This study aims to explore the mechanism by which anlotinib ameliorates platinum resistance in OC cells.

METHODS

Cell viability was detected by the 3-4,5-dimethylthiazol-2,5-diphenyltetrazolium bromide (MTT) method, and the apoptosis rate and changes in the cell cycle distribution were evaluated by flow cytometry. Bioinformatics analysis was used to predict the potential gene target of anlotinib in DDP-resistance SKOV3 cells, and its expression was verifies it by RT-qPCR, western blotting and immunofluorescence staining. Finally, ovarian cancer cells overexpressing AURKA were constructed, and the predicted results were verified by animal experiments.

RESULTS

Anlotinib effectively induced apoptosis and G2/M arrest in OC cells and decreased the proportion of EdU-positive cells. AURKA was identified as a possible key target of anlotinib for inhibiting tumorigenic behaviors in SKOV3/DDP cells. Through combined immunofluorescence and western blot analyses, it was demonstrated that anlotinib could effectively inhibit the protein expression of AURKA and upregulate the expression of p53/p21, CDK1, and Bax protein. After overexpression of AURKA in OC cells, the induction of apoptosis and G2/M arrest by anlotinib were significantly inhibited. Anlotinib also effectively inhibited the growth of tumors in nude mice injected with OC cells.

CONCLUSIONS

This study demonstrated that anlotinib can induce apoptosis and G2/M arrest in cisplatin-resistant ovarian cancer cells through the AURKA/p53 pathway.

cAMP-Dependent Signaling and Ovarian Cancer

cAMP-dependent pathway is one of the most significant signaling cascades in healthy and neoplastic ovarian cells. Working through its major effector proteins-PKA and EPAC-it regulates gene expression and many cellular functions. PKA promotes the phosphorylation of cAMP response element-binding protein (CREB) which mediates gene transcription, cell migration, mitochondrial homeostasis, cell proliferation, and death. EPAC, on the other hand, is involved in cell adhesion, binding, differentiation, and interaction between cell junctions. Ovarian cancer growth and metabolism largely depend on changes in the signal processing of the cAMP-PKA-CREB axis, often associated with neoplastic transformation, metastasis, proliferation, and inhibition of apoptosis. In addition, the intracellular level of cAMP also determines the course of other pathways including AKT, ERK, MAPK, and mTOR, that are hypo- or hyperactivated among patients with ovarian neoplasm. With this review, we summarize the current findings on cAMP signaling in the ovary and its association with carcinogenesis, multiplication, metastasis, and survival of cancer cells. Additionally, we indicate that targeting particular stages of cAMP-dependent processes might provide promising therapeutic opportunities for the effective management of patients with ovarian cancer.

Phosphodiesterase 10A (PDE10A) as a novel target to suppress β-catenin and RAS signaling in epithelial ovarian cancer

A leading theory for ovarian carcinogenesis proposes that inflammation associated with incessant ovulation is a driver of oncogenesis. Consistent with this theory, nonsteroidal anti-inflammatory drugs (NSAIDs) exert promising chemopreventive activity for ovarian cancer. Unfortunately, toxicity is associated with long-term use of NSAIDs due to their cyclooxygenase (COX) inhibitory activity. Previous studies suggest the antineoplastic activity of NSAIDs is COX independent, and rather may be exerted through phosphodiesterase (PDE) inhibition. PDEs represent a unique chemopreventive target for ovarian cancer given that ovulation is regulated by cyclic nucleotide signaling. Here we evaluate PDE10A as a novel therapeutic target for ovarian cancer. Analysis of The Cancer Genome Atlas (TCGA) ovarian tumors revealed PDE10A overexpression was associated with significantly worse overall survival for patients. PDE10A expression also positively correlated with the upregulation of oncogenic and inflammatory signaling pathways. Using small molecule inhibitors, Pf-2545920 and a novel NSAID-derived PDE10A inhibitor, MCI-030, we show that PDE10A inhibition leads to decreased ovarian cancer cell growth and induces cell cycle arrest and apoptosis. We demonstrate these pro-apoptotic properties occur through PKA and PKG signaling by using specific inhibitors to block their activity. PDE10A genetic knockout in ovarian cancer cells through CRISP/Cas9 editing lead to decreased cell proliferation, colony formation, migration and invasion, and in vivo tumor growth. We also demonstrate that PDE10A inhibition leads to decreased Wnt-induced β-catenin nuclear translocation, as well as decreased EGF-mediated activation of RAS/MAPK and AKT pathways in ovarian cancer cells. These findings implicate PDE10A as novel target for ovarian cancer chemoprevention and treatment.

Targeting Adenylate Cyclase Family: New Concept of Targeted Cancer Therapy

The adenylate cyclase (ADCY) superfamily is a group of glycoproteins regulating intracellular signaling. ADCYs act as key regulators in the cyclic adenosine monophosphate (cAMP) signaling pathway and are related to cell sensitivity to chemotherapy and ionizing radiation. Many members of the superfamily are detectable in most chemoresistance cases despite the complexity and unknownness of the specific mechanism underlying the role of ADCYs in the proliferation and invasion of cancer cells. The overactivation of ADCY, as well as its upstream and downstream regulators, is implicated as a major potential target of novel anticancer therapies and markers of exceptional responders to chemotherapy. The present review focuses on the oncogenic functions of the ADCY family and emphasizes the possibility of the mediating roles of deleterious nonsynonymous single nucleotide polymorphisms (nsSNPs) in ADCY as a prognostic therapeutic target in modulating resistance to chemotherapy and immunotherapy. It assesses the mediating roles of ADCY and its counterparts as stress regulators in reprogramming cancer cell metabolism and the tumor microenvironment. Additionally, the well-evaluated inhibitors of ADCY-related signaling, which are under clinical investigation, are highlighted. A better understanding of ADCY-induced signaling and deleterious nsSNPs (p.E1003K and p.R1116C) in ADCY6 provides new opportunities for developing novel therapeutic strategies in personalized oncology and new approaches to enhance chemoimmunotherapy efficacy in treating various cancers.

GANT61 elevates chemosensitivity to cisplatin through regulating the Hedgehog, AMPK and cAMP pathways in ovarian cancer

Background: This study aimed to explore the effect of GANT61 on ovarian cancer (OC) chemosensitivity. Materials & methods: OC cells (Caov-3 and SKOV-3) were treated by GANT61 alone or combined with cisplatin/taxol. The mRNA sequencing was conducted, followed by rescue experiments. Results: GANT61 reduced OC cell viability in a dose-dependent manner and enhanced chemosensitivity to cisplatin but not to taxol. In total, 545 dysregulated genes were identified after the addition of GANT61 to cisplatin-treated OC cells, which were enriched in the AMPK, Hedgehog and cAMP pathways, then further validated by western blot. Furthermore, rescue experiments observed that AMPK pathway inhibitor and cAMP pathway inhibitor attenuated GANT61's chemosensitivity to cisplatin. Conclusion: GANT61 enforces OC chemosensitivity to cisplatin by regulating the Hedgehog, AMPK and cAMP pathways.

Silencing of miR-1246 Induces Cell Cycle Arrest and Apoptosis in Cisplatin-Resistant Ovarian Cancer Cells by Promoting ZNF23 Transcription

Ovarian cancer (OC) is the most frequent cause of death among patients with gynecologic malignancies. In recent years, the development of cisplatin (DDP) resistance has become an important reason for the poor prognosis of OC patients. Therefore, it is vital to explore the mechanism of DDP resistance in OC. In this study, microRNA-1246 (miR-1246) expression in OC and DDP-resistant OC cells was determined by RT-qPCR, and chemosensitivity to DDP was assessed by the CCK-8 assay. A dual-luciferase reporter assay was performed to confirm the interaction between miR-1246 and zinc finger 23 (ZNF23), while changes in ZNF23 expression were monitored by RT-qPCR, immunofluorescence, and western blot assays. Moreover, cell proliferation, cycle phase, and apoptosis were determined by EdU staining, flow cytometry, TUNEL staining, and Hoechst staining. Our data showed that miR-1246 was highly expressed in DDP-resistant OVCAR-3 and TOV-112D cells. Functionally, overexpression of miR-1246 markedly enhanced DDP resistance and cell proliferation, and suppressed cell cycle arrest and apoptosis of OC cells. Inhibition of miR-1246 expression significantly attenuated DDP resistance and cell proliferation, and increased cell cycle arrest and apoptosis in DDP-resistant OC cells. Furthermore, ZNF23 was identified as a target gene of miR-1246, and ZNF23 protein expression was notably downregulated in DDP-resistant OC cells. Moreover, overexpression of miR-1246 significantly downregulated the ZNF23 levels in OVCAR-3 and TOV-112D cells, and inhibition of miR-1246 upregulated the ZNF23 levels in the DDP-resistant OVCAR-3 and TOV-112D cells. In conclusion, miR-1246 might be a novel regulator of DDP-resistant OC that functions by regulating ZNF23 expression in DDP-resistant cells, as well as cell proliferation, cell cycle progression, and apoptosis.

Roflumilast, a type of phosphodiesterase 4 inhibitor, can reduce intestinal injury caused by sepsis

Sepsis is a systemic inflammatory response syndrome caused by infection, which has a complex mechanism. The gastrointestinal tract is commonly the first organ affected by sepsis, but intestinal disease itself can also induce sepsis. Roflumilast has been found to exert anti-inflammatory effects and, thus, the present study sought to examine its effect on intestinal damage caused by sepsis. In vivo studies were conducted using cecal ligation and puncture rat models, and in vitro experiments were performed using IEC-6 cells. The intestinal cells were first induced with lipopolysaccharide and the induced cells were then treated with roflumilast to evaluate its effects on phosphodiesterase (PDE)4 expression, intestinal function indices, release of inflammatory factors and cell apoptosis. The expression level of PDE4 in the small intestinal tissue of septic rats was found to be significantly higher compared with that in the normal group, suggesting that PDE4 may play a key role in intestinal injury caused by sepsis. It was found that roflumilast reduced PDE4 expression, as well as the levels of intestinal function indices, including lactate dehydrogenase, diamino oxidase and intestinal fatty acid-binding protein, in intestinal cells. Moreover, roflumilast reduced cellular damage, the release of inflammatory factors and apoptosis. In summary, the findings of the present study indicated that roflumilast can relieve the inflammation and apoptosis of intestinal cells caused by sepsis and can promote their functional recovery. These findings may promote the expansion of the clinical application of roflumilast in the future.

Multi-Omics Analysis Identifying Key Biomarkers in Ovarian Cancer

Ovarian cancer is one of the most common malignant tumors. Here, we aimed to study the expression and function of the CREB1 gene in ovarian cancer via the bioinformatic analyses of multiple databases. Previously, the prognosis of ovarian cancer was based on single-factor or single-gene studies. In this study, different bioinformatics tools (such as TCGA, GEPIA, UALCAN, MEXPRESS, and Metascape) have been used to assess the expression and prognostic value of the CREB1 gene. We used the Reactome and cBioPortal databases to identify and analyze CREB1 mutations, copy number changes, expression changes, and protein-protein interactions. By analyzing data on the CREB1 differential expression in ovarian cancer tissues and normal tissues from 12 studies collected from the "Human Protein Atlas" database, we found a significantly higher expression of CREB1 in normal ovarian tissues. Using this database, we collected information on the expression of 25 different CREB-related proteins, including TP53, AKT1, and AKT3. The enrichment of these factors depended on tumor metabolism, invasion, proliferation, and survival. Individualized tumors based on gene therapy related to prognosis have become a new possibility. In summary, we established a new type of prognostic gene profile for ovarian cancer using the tools of bioinformatics.

Natural borneol sensitizes human glioma cells to cisplatin-induced apoptosis by triggering ROS-mediated oxidative damage and regulation of MAPKs and PI3K/AKT pathway

Context: Cisplatin-based chemotherapy was widely used in treating human malignancies. However, side effects and chemoresistance remains the major obstacle.Objective: To verify whether natural borneol (NB) can enhance cisplatin-induced glioma cell apoptosis and explore the mechanism.Materials and methods: Cytotoxicity of cisplatin and/or NB towards U251 and U87 cells were determined with the MTT assay. Cells were treated with 0.25-80 μg/mL cisplatin and/or 5-80 μM NB for 48 h. The effects of NB and/or cisplatin on apoptosis and cell cycle distribution were quantified by flow cytometric analysis. Protein expression was detected by western blotting. ROS generation was conducted by measuring and visualising an oxidation-sensitive fluorescein DCFH-DA.Results: NB synergistically enhanced the anticancer efficacy of cisplatin in human glioma cells. Co-treatment of 40 μg/mL NB and 40 μg/mL cisplatin significantly inhibited U251 cell viability from 100% to 28.2% and increased the sub-G1 population from 1.4% to 59.3%. Further detection revealed that NB enhanced cisplatin-induced apoptosis by activating caspases and triggering reactive oxygen species (ROS) overproduction as evidenced by the enhancement of green fluorescence intensity from 265% to 645%. ROS-mediated DNA damage was observed as reflected by the activation of ATM/ATR, p53 and histone. Moreover, MAPKs and PI3K/AKT pathways also contributed to co-treatment-induced U251 cell growth inhibition. ROS inhibition by antioxidants effectively improved MAPKs and PI3K/AKT functions and cell viability, indicating that NB enhanced cisplatin-induced cell growth in a ROS-dependent manner.Discussion and conclusions: Natural borneol had the potential to sensitise human glioma cells to cisplatin-induced apoptosis with potential application in the clinic.

MicroRNA-mediated autophagy regulation in cancer therapy: The role in chemoresistance/chemosensitivity

Chemoresistance has doubled the effort needed to reach an effective treatment for cancer. Now, scientists should consider molecular pathways and mechanisms involved in chemoresistance to overcome cancer. Autophagy is a "self-digestion" mechanism in which potentially toxic and aged organelles and macromolecules are degraded. Increasing evidence has shown that autophagy possesses dual role in cancer cells (onco-suppressor or oncogene). So, it is vital to identify its role in cancer progression and malignancy. MicroRNAs (miRs) are epigenetic factors capable of modulation of autophagy in cancer cells. In the current review, we emphasize on the relationship between miRs and autophagy in cancer chemotherapy. Besides, we discuss upstream mediators of miR/autophagy axis in cancer chemotherapy including long non-coding RNAs, circular RNAs, Nrf2 c-Myc, and HIF-1α. At the final section, we provide a discussion about how anti-tumor compounds affect miR/autophagy axis in ensuring chemosensitivity. These topics are described in this review to show how autophagy inhibition/induction can lead to chemosensitivity/chemoresistance, and miRs are considered as key players in these discussions.

Identification of novel genes in testicular cancer microenvironment based on ESTIMATE algorithm-derived immune scores

Testicular cancer is the most common solid malignancy among young men. We downloaded data of testicular cancer patients from The Cancer Genome Atlas database to find novel genes in the testicular cancer microenviroment based on ESTIMATE algorithm-derived immune scores. A total of 156 cases of testicular cancer were included in this study and 165 cases of normal testicular tissues were used. We divided the testicular cancer patients into high- and low-score groups based on their immune scores. We identified 1,226 differentially expressed genes (fold change > 2, false discovery rate < 0.05), including 688 downregulated genes and 538 upregulated genes, between these two groups. The top Gene Ontology terms were involved in the immune response-regulating cell surface receptor signaling pathway, immune response-activating cell surface receptor signaling pathway, external side of the plasma membrane, and receptor ligand activity. By performing the Kyoto Encyclopedia of Genes and Genomes analysis, we demonstrated that cAMP signaling pathway was highly enriched among these differentially expressed genes. High expression of LINC01564, LINC02208, ODAM, RNA5SP111, and RNU6-196P were found to be associated with poor overall survival. The expression of genes was further validated by the Human Protein Atlas and only ALB and IFNG were demonstrated to be differentially expressed between testis tissue and testicular cancer tissue.

Glucocorticoid Receptor α Mediates Roflumilast's Ability to Restore Dexamethasone Sensitivity in COPD

Background

Glucocorticoids are commonly prescribed to treat inflammation of the respiratory system; however, they are mostly ineffective for controlling chronic obstructive pulmonary disease (COPD)-associated inflammation. This study aimed to elucidate the molecular mechanisms responsible for such glucocorticoid inefficacy in COPD, which may be instrumental to providing better patient outcomes. Roflumilast is a selective phosphodiesterase-4 (PDE4) inhibitor with anti-inflammatory properties in severe COPD patients who have a history of exacerbations. Roflumilast has a suggested ability to mitigate glucocorticoid resistance, but the mechanism is unknown.

Methods

To understand the mechanism that mediates roflumilast-induced restoration of glucocorticoid sensitivity in COPD, we tested the role of glucocorticoid receptor α (GRα). Roflumilast's effects on GRα expression and transcriptional activity were assessed in bronchial epithelial cells from COPD patients.

Results

We found that both GRα expression and activity are downregulated in bronchial epithelial cells from COPD patients and that roflumilast stimulates both GRα mRNA synthesis and GRα's transcriptional activity in COPD bronchial epithelial cells. We also demonstrate that roflumilast enhances dexamethasone's ability to suppress pro-inflammatory mediator production, in a GRα-dependent manner.

Discussion

Our findings highlight the significance of roflumilast-induced GRα upregulation for COPD therapeutic strategies by revealing that roflumilast restores glucocorticoid sensitivity by sustaining GRα expression.

A perspective profile of ADCY1 in cAMP signaling with drug-resistance in lung cancer

Adenylate cyclase 1 (ADCY1 or AC1) is a member of ADCY superfamily and was primarily found to be expressed in the brain. ADCY1 is responsible for catalyzing ATP to cyclic AMP (cAMP). As a secondary messenger, cAMP can regulate plenty of cellular activities. cAMP can perform its regulation in cellular transport through the binding to cAMP dependent protein kinases (PKAs), cAMP-activated guanine exchange factors (EPACs) and cyclic nucleotide-gated channels functioning in transduction of sensory signals (CNGs). Lung cancer is one of the leading factors of cancer-related death worldwide. Platinum-based chemotherapy is the first-line treatment for advanced lung cancer patients. In addition, surgical treatment, radiation treatment, and molecular targeted therapy are also therapeutic options for lung cancer patients in clinical settings. However, drug resistance and toxicity are the major obstacles that affect chemotherapy outcome and prognosis of lung cancer patients. And the therapeutic efficiency and adverse effects are varying with each individual. In recent years, investigations based on genetic sequencing have revealed the emerging role of ADCY1 mutations in affecting drug efficiency in various cancers such as lung cancer, esophageal cancer and colorectal cancer. The potential function of ADCY1 in chemotherapy resistance is of great importance to be noticed and investigated.

GPRC5A facilitates cell proliferation through cell cycle regulation and correlates with bone metastasis in prostate cancer

The prognosis of patients with progressive prostate cancers that are hormone refractory and/or have bone metastasis is poor. Multiple therapeutic targets to improve prostate cancer patient survival have been investigated, including orphan GPCRs. In our study, we identified G Protein-Coupled Receptor Class C Group 5 Member A (GPRC5A) as a candidate therapeutic molecule using integrative gene expression analyses of registered data sets for prostate cancer cell lines. Kaplan-Meier analysis of TCGA data sets revealed that patients who have high GPRC5A expression had significantly shorter overall survival. PC3 prostate cancer cells with CRISPR/Cas9-mediated GPRC5A knockout exhibited significantly reduced cell proliferation both in vitro and in vivo. RNA-seq revealed that GPRC5A KO PC3 cells had dysregulated expression of cell cycle-related genes, leading to cell cycle arrest at the G2/M phase. Furthermore, the registered gene expression profile data set showed that the expression level of GPRC5A in original lesions of prostate cancer patients with bone metastasis was higher than that without bone metastasis. In fact, GPRC5A KO PC3 cells failed to establish bone metastasis in xenograft mice models. In addition, our clinical study revealed that GPRC5A expression levels in prostate cancer patient samples were significantly correlated with bone metastasis as well as the patient's Gleason score (GS). Combined assessment with the immunoreactivity of GPRC5A and GS displayed higher specificity for predicting the occurrence of bone metastasis. Together, our findings indicate that GPRC5A can be a possible therapeutic target and prognostic marker molecule for progressive prostate cancer.

Roflumilast enhances cisplatin-sensitivity and reverses cisplatin-resistance of ovarian cancer cells via cAMP/PKA/CREB-FtMt signalling axis

OBJECTIVE

We previously demonstrated the roflumilast inhibited cell proliferation and increased cell apoptosis in ovarian cancer. In this study, we aimed to investigate the roles of roflumilast in development of cisplatin (DDP)-sensitive and -resistant ovarian cancer.

METHODS

OVCAR3 and SKOV3 were selected and the corresponding DDP-resistant cells were constructed. Cell viability, proliferation, apoptosis, cycle were performed. Expression cAMP, PKA, CREB, phosphorylation of CREB and FtMt were detected. The roles of roflumilast in development of DDP-sensitive and -resistant ovarian cancer were confirmed by xenograft model.

RESULTS

Roflumilast + DDP inhibited cell proliferation, and induced cell apoptosis and G0/G1 arrest in OVCAR3 and SKOV3 cells, roflumilast induced expression of FtMt, the activity of cAMP and PKA and phosphorylation of CREB in ovarian cancer cells and the above-effect were inhibited by H89. Downregulation of CREB inhibited the roflumilast-increased DDP sensitivity of ovarian cancer cells, and the roflumilast-induced FtMt expression and phosphorylation of CREB. Also, roflumilast reversed cisplatin-resistance, and induced expression of FtMt and activation of cAMP/PKA/CREB in DDP-resistant ovarian cancer cells. Similarly, treated with H89 or downregulation of CREB inhibited the changes induced by roflumilast. In vivo, roflumilast inhibited the development of SKOV3 or SKOV3-DDP-R xenograft models.

CONCLUSIONS

Roflumilast enhanced DDP sensitivity and reversed the DDP resistance of ovarian cancer cells via activation of cAMP/PKA/CREB pathway and upregulation of the downstream FtMt expression, which has great promise in clinical treatment.