Identification of candidate biomarkers of therapeutic response to docetaxel by proteomic profiling

Clinical validation of circulating GDF15/MIC-1 as a marker of response to docetaxel and survival in men with metastatic castration-resistant prostate cancer

BACKGROUND

Elevated circulating growth differentiation factor (GDF15/MIC-1), interleukin 4 (IL4), and IL6 levels were associated with resistance to docetaxel in an exploratory cohort of men with metastatic castration-resistant prostate cancer (mCRPC). This study aimed to establish level 2 evidence of cytokine biomarker utility in mCRPC.

METHODS

IntVal: Plasma samples at baseline (BL) and Day 21 docetaxel (n = 120). ExtVal: Serum samples at BL and Day 42 of docetaxel (n = 430). IL4, IL6, and GDF15 levels were measured by ELISA. Monocytes and dendritic cells were treated with 10% plasma from men with high or low GDF15 or recombinant GDF15.

RESULTS

IntVal: Higher GDF15 levels at BL and Day 21 were associated with shorter overall survival (OS) (BL; p = 0.03 and Day 21; p = 0.004). IL4 and IL6 were not associated with outcomes. ExtVal: Higher GDF15 levels at BL and Day 42 predicted shorter OS (BL; p < 0.0001 and Day 42; p < 0.0001). Plasma from men with high GDF15 caused an increase in CD86 expression on monocytes (p = 0.03), but was not replicated by recombinant GDF15.

CONCLUSIONS

Elevated circulating GDF15 is associated with poor prognosis in men with mCRPC receiving docetaxel and may be a marker of changes in the innate immune system in response to docetaxel resistance. These findings provide a strong rationale to consider GDF15 as a biomarker to guide a therapeutic trial of drugs targeting the innate immune system in combination with docetaxel in mCRPC.

Unveiling Gene Regulatory Networks That Characterize Difference of Molecular Interplays Between Gastric Cancer Drug Sensitive and Resistance Cell Lines

Gastric cancer is a leading cause of cancer-related deaths globally and chemotherapy is widely accepted as the standard treatment for gastric cancer. However, drug resistance in cancer cells poses a significant obstacle to the success of chemotherapy, limiting its effectiveness in treating gastric cancer. Although many studies have been conducted to unravel the mechanisms of acquired drug resistance, the existing studies were based on abnormalities of a single gene, that is, differential gene expression (DGE) analysis. Single gene-based analysis alone is insufficient to comprehensively understand the mechanisms of drug resistance in cancer cells, because the underlying processes of the mechanism involve perturbations of the molecular interactions. To uncover the mechanism of acquired gastric cancer drug resistance, we perform for identification of differentially regulated gene networks between drug-sensitive and drug-resistant cell lines. We develop a computational strategy for identifying phenotype-specific gene networks by extending the existing method, CIdrgn, that quantifies the dissimilarity of gene networks based on comprehensive information of network structure, that is, regulatory effect between genes, structure of edge, and expression levels of genes. To enhance the efficiency of identifying differentially regulated gene networks and improve the biological relevance of our findings, we integrate additional information and incorporate knowledge of network biology, such as hubness of genes and weighted adjacency matrices. The outstanding capabilities of the developed strategy are validated through Monte Carlo simulations. By using our strategy, we uncover gene regulatory networks that specifically capture the molecular interplays distinguishing drug-sensitive and drug-resistant profiles in gastric cancer. The reliability and significance of the identified drug-sensitive and resistance-specific gene networks, as well as their related markers, are verified through literature. Our analysis for differentially regulated gene network identification has the capacity to characterize the drug-sensitive and resistance-specific molecular interplays related to mechanisms of acquired drug resistance that cannot be revealed by analysis based solely on abnormalities of a single gene, for example, DGE analysis. Through our analysis and comprehensive examination of relevant literature, we suggest that targeting the suppressors of the identified drug-resistant markers, such as the Melanoma Antigen (MAGE) family, Trefoil Factor (TFF) family, and Ras-Associated Binding 25 (RAB25), while enhancing the expression of inducers of the drug sensitivity markers [e.g., Serum Amyloid A (SAA) family], could potentially reduce drug resistance and enhance the effectiveness of chemotherapy for gastric cancer. We expect that the developed strategy will serve as a useful tool for uncovering cancer-related phenotype-specific gene regulatory networks that provide essential clues for uncovering not only drug resistance mechanisms but also complex biological systems of cancer.

The potential of using circulating tumour cells and their gene expression to predict docetaxel response in metastatic prostate cancer

Background

Docetaxel improves overall survival (OS) in castration-resistant prostate cancer (PCa) (CRPC) and metastatic hormone-sensitive PCa (mHSPC). However, not all patients respond due to inherent and/or acquired resistance. There remains an unmet clinical need for a robust predictive test to stratify patients for treatment. Liquid biopsy of circulating tumour cell (CTCs) is minimally invasive, can provide real-time information of the heterogeneous tumour and therefore may be a potentially ideal docetaxel response prediction biomarker.

Objective

In this study we investigate the potential of using CTCs and their gene expression to predict post-docetaxel tumour response, OS and progression free survival (PFS).

Methods

Peripheral blood was sampled from 18 mCRPC and 43 mHSPC patients, pre-docetaxel treatment, for CTC investigation. CTCs were isolated using the epitope independent Parsortix^® system and gene expression was determined by multiplex RT-qPCR. We evaluated CTC measurements for post-docetaxel outcome prediction using receiver operating characteristics and Kaplan Meier analysis.

Results

Detection of CTCs pre-docetaxel was associated with poor patient outcome post-docetaxel treatment. Combining total-CTC number with PSA and ALP predicted lack of partial response (PR) with an AUC of 0.90, p= 0.037 in mCRPC. A significantly shorter median OS was seen in mCRPC patients with positive CTC-score (12.80 vs. 37.33 months, HR= 5.08, p= 0.0005), ≥3 total-CTCs/7.5mL (12.80 vs. 37.33 months, HR= 3.84, p= 0.0053), ≥1 epithelial-CTCs/7.5mL (14.30 vs. 37.33 months, HR= 3.89, p= 0.0041) or epithelial to mesenchymal transitioning (EMTing)-CTCs/7.5mL (11.32 vs. 32.37 months, HR= 6.73, p= 0.0001). Significantly shorter PFS was observed in patients with ≥2 epithelial-CTCs/7.5mL (7.52 vs. 18.83 months, HR= 3.93, p= 0.0058). mHSPC patients with ≥5 CTCs/7.5mL had significantly shorter median OS (24.57 vs undefined months, HR= 4.14, p= 0.0097). In mHSPC patients, expression of KLK2, KLK4, ADAMTS1, ZEB1 and SNAI1 was significantly associated with shorter OS and/or PFS. Importantly, combining CTC measurements with clinical biomarkers increased sensitivity and specificity for prediction of patient outcome.

Conclusion

While it is clear that CTC numbers and gene expression were prognostic for PCa post-docetaxel treatment, and CTC subtype analysis may have additional value, their potential predictive value for docetaxel chemotherapy response needs to be further investigated in large patient cohorts.

Emerging Proteins in CRPC: Functional Roles and Clinical Implications

Prostate cancer (PCa) is the most common cancer in men in the western world, but the lack of specific and sensitive markers often leads to overtreatment of prostate cancer which eventually develops into castration-resistant prostate cancer (CRPC). Novel protein markers for diagnosis and management of CRPC will be promising. In this review, we systematically summarize and discuss the expression pattern of emerging proteins in tissue, cell lines, and serum when castration-sensitive prostate cancer (CSPC) progresses to CRPC; focus on the proteins involved in CRPC growth, invasion, metastasis, metabolism, and immune microenvironment; summarize the current understanding of the regulatory mechanisms of emerging proteins in CSPC progressed to CRPC at the molecular level; and finally summarize the clinical applications of emerging proteins as diagnostic marker, prognostic marker, predictive marker, and therapeutic marker.

Macrophage inhibitory cytokine-1 in cancer: Beyond the cellular phenotype

Despite technological advances in diagnostic abilities and improved treatment methods, the burden of cancers remains high, leading to significant morbidity and mortality. One primary reason is that cancer cell secretory factors modulate the tumor microenvironment, supporting tumor growth and circumvents anticancer activities of conventional therapies. Macrophage inhibitory cytokine-1 (MIC-1) is a pleiotropic cytokine elevated in various cancers. MIC-1 regulates various cancer hallmarks, including sustained proliferation, tumor-promoting inflammation, avoiding immune destruction, inducing invasion, metastasis, angiogenesis, and resisting cell death. Despite these facts, the molecular regulation and downstream signaling of MIC-1 in cancer remain elusive, partly because its receptor (GFRAL) was unknown until recently. Binding of MIC-1 to GFRAL recruits the coreceptor tyrosine kinase RET to execute its downstream signaling. So far, studies have shown that GFRAL expression is restricted to the brain stem and is responsible for MIC-1/GFRAL/RET-mediated metabolic disorders. Nevertheless, abundant levels of MIC-1 expression have been reported in all cancer types and have been proposed as a surrogate biomarker. Given the ubiquitous expression of MIC-1 in cancers, it is crucial to understand both upstream regulation and downstream MIC-1/GFRAL/RET signaling in cancer hallmark traits.

Proteome profiling of enzalutamide-resistant cell lines and serum analysis identified ALCAM as marker of resistance in castration-resistant prostate cancer

Enzalutamide (ENZA) is a frequently used therapy in metastatic castration‐resistant prostate cancer (mCRPC). Baseline or acquired resistance to ENZA have been observed, but the molecular mechanisms of resistance are poorly understood. We aimed to identify proteins involved in ENZA resistance and to find therapy‐predictive serum markers. We performed comparative proteome analyses on ENZA‐sensitive parental (LAPC4, DuCaP) and ‐resistant prostate cancer cell lines (LAPC4‐ENZA, DuCaP‐ENZA) using liquid chromatography tandem mass spectrometry (LC‐MS/MS). The top four most promising candidate markers were selected using bioinformatic approaches. Serum concentrations of selected markers (ALCAM, AGR2, NDRG1, IDH1) were measured in pretreatment samples of 72 ENZA‐treated mCRPC patients using ELISA. In addition, ALCAM serum levels were measured in 101 Abiraterone (ABI) and 100 Docetaxel (DOC)‐treated mCRPC patients' baseline samples. Results were correlated with clinical and follow‐up data. The functional role of ALCAM in ENZA resistance was assessed in vitro using siRNA. Our proteome analyses revealed 731 significantly differentially abundant proteins between ENZA‐sensitive and ‐resistant cells and our filtering methods identified four biomarker candidates. Serum analyses of these proteins revealed only ALCAM to be associated with poor patient survival. Furthermore, higher baseline ALCAM levels were associated with poor survival in ABI‐ but not in DOC‐treated patients. In LAPC4‐ENZA resistant cells, ALCAM silencing by siRNA knockdown resulted in significantly enhanced ENZA sensitivity. Our analyses revealed that ALCAM serum levels may help to identify ENZA‐ and ABI‐resistant patients and may thereby help to optimize future clinical decision‐making. Our functional analyses suggest the possible involvement of ALCAM in ENZA resistance.

Inflammatory molecules facilitate the development of docetaxel-resistant prostate cancer cells in vitro and in vivo

Numerous molecular mechanisms have been found to contribute to docetaxel-induced resistance in prostate cancer (PCa). In this study, the changes in gene expression profiles of multidrug resistant PCa cells that were established in response to docetaxel were determined using microarray analysis. In addition to alterations in the expression of multidrug resistance-associated genes, the expression levels of multiple inflammatory molecules, in particular IL-6, significantly increased in resistant cells in vitro and in vivo, which further increased with the development of drug resistance following microarray, qRT-PCR and ELISA analysis. Compared with parental cells, resistant cells also presented with stronger activation of multiple IL-6-associated signaling pathways STAT1/3, NF-κB, and PI3K/AKT. Inactivation of IL-6 using a neutralizing antibody resulted in a slight effect on the sensitivity of resistant cells to docetaxel, while blockade of of STAT1/3, NF-κB, or PI3K/AKT signaling significantly resensitized resistant cells to docetaxel. Of note, simultaneous inactivation of IL-6 and STAT1/3, PI3K/AKT or NF-κB further enhanced the sensitivity of the resistant cells to docetaxel. Thus, inflammatory molecules, in particular IL-6, and IL-6-associated signaling pathways NF-κB, STAT1/3, and PI3K/AKT, are crucial mediators of the development of docetaxel-resistance in PCa. Targeting inflammatory molecules and signaling pathways could be a potential therapeutic option for the intervention of drug resistance in PCa.

Pathophysiological role of growth differentiation factor 15 (GDF15) in obesity, cancer, and cachexia

Growth differentiation factor 15 or macrophage inhibitory cytokine-1 (GDF15/MIC-1) is a divergent member of the transforming growth factor β superfamily and has a diverse pathophysiological roles in cancers, cardiometabolic disorders, and other diseases. GDF15 controls hematopoietic growth, energy homeostasis, adipose tissue metabolism, body growth, bone remodeling, and response to stress signals. The role of GDF15 in cancer development and progression is complicated and depends on the specific cancer type, stage, and tumor microenvironment. Recently, research on GDF15 and GDF15-associated signaling has accelerated due to the identification of the GDF15 receptor: glial cell line-derived neurotrophic factor (GDNF) family receptor α-like (GFRAL). Therapeutic interventions to target GDF15 and/or GFRAL revealed the mechanisms that drive its activity and might improve overall outcomes of patients with metabolic disorders and cancer. This review highlights the structure and functions of GDF15 and its receptor, emphasizing the pleiotropic role of GDF15 in obesity, tumorigenesis, metastasis, immunomodulation, and cachexia.

Mechanism-Centric Approaches for Biomarker Detection and Precision Therapeutics in Cancer

Biomarker discovery is at the heart of personalized treatment planning and cancer precision therapeutics, encompassing disease classification and prognosis, prediction of treatment response, and therapeutic targeting. However, many biomarkers represent passenger rather than driver alterations, limiting their utilization as functional units for therapeutic targeting. We suggest that identification of driver biomarkers through mechanism-centric approaches, which take into account upstream and downstream regulatory mechanisms, is fundamental to the discovery of functionally meaningful markers. Here, we examine computational approaches that identify mechanism-centric biomarkers elucidated from gene co-expression networks, regulatory networks (e.g., transcriptional regulation), protein-protein interaction (PPI) networks, and molecular pathways. We discuss their objectives, advantages over gene-centric approaches, and known limitations. Future directions highlight the importance of input and model interpretability, method and data integration, and the role of recently introduced technological advantages, such as single-cell sequencing, which are central for effective biomarker discovery and time-cautious precision therapeutics.

Which Way to Choose for the Treatment of Metastatic Prostate Cancer: A Case Report and Literature Review

Background

Prostate cancer (PCa) is the second most common cancer among males in the world and the majority of patients will eventually progress to the metastatic phase. How to choose an effective way for the treatment of metastatic PCa, especially in the later stage of the disease is still confusing. Herein we reported the case of a patient diagnosed with metastatic PCa and conducted a literature review on this issue.

Case Presentation

A 57-year-old man with metastatic PCa had been managed by Dr. J.P. since April 2012 when the patient was admitted to the Third Affiliated Hospital of Sun Yat-sen University by aggravating frequent urination and dysuria. The prostate-specific antigen (PSA) concentration was 140 ng/ml, and the diagnosis of PCa was confirmed by prostate biopsy, with Gleason score 4 + 5 = 9. Chest CT and bone scan indicated multiple metastases in the lungs and bones. Triptorelin, bicalutamide, zoledronic acid, and docetaxel were then administered, six cycles later, the metastatic tumors in the lungs disappeared and those in the bones lessened significantly, along with a remarkable reduction in PSA level (< 2 ng/ml). Intermittent androgen deprivation was subsequently conducted until August 2018, when the serum PSA level was found to be 250 ng/ml, again docetaxel 75 mg/m² was administered immediately but the patient was intolerant this time. Instead, abiraterone was administered until March 2019 because of intolerable gastrointestinal side-effects and increasing PSA level. In October 2019, the patient came to our center, a modified approach of docetaxel (day 1 40 mg/m² + day 8 35 mg/m²) was administered. Luckily, the PSA level decreased rapidly, the bone pain was greatly relieved, and no obvious side effects occurred. However, four cycles later, docetaxel failed to work anymore, the metastatic tumor in the liver progressed. We proposed several regimens as alternatives, but they were soon denied due to the high prices or unavailability or uncertain effect of the drugs. In addition, the patient’s condition deteriorated speedily and can no longer bear any aggressive treatment. Finally, the patient died of multiple organ failure in August 2020.

Conclusion

The experiences of this case provide valuable evidence and reference for the treatment choices of metastatic PCa, in some circumstances modified and advanced regimens may produce unexpected effects.

Macrophage inhibitory cytokine-1 induced by a high-fat diet promotes prostate cancer progression by stimulating tumor-promoting cytokine production from tumor stromal cells

Background

Recent studies have indicated that a high‐fat diet (HFD) and/or HFD‐induced obesity may influence prostate cancer (PCa) progression, but the role of HFD in PCa microenvironment is unclear. This study aimed to delineate the molecular mechanisms of PCa progression under HFD milieus and define the stromal microenvironment focusing on macrophage inhibitory cytokine‐1 (MIC‐1) activation.

Methods

We investigated the effects of HFD on PCa stromal microenvironment and MIC‐1 signaling activation using PC‐3M‐luc‐C6 PCa model mice fed with HFD or control diet. Further, we explored the effect of periprostatic adipocytes derived from primary PCa patients on activation and cytokine secretion of prostate stromal fibroblasts. Expression patterns and roles of MIC‐1 signaling on human PCa stroma activation and progression were also investigated.

Results

HFD stimulated PCa cell growth and invasion as a result of upregulated MIC‐1 signaling and subsequently increased the secretion of interleukin (IL)‐8 and IL‐6 from prostate stromal fibroblasts in PC‐3M‐luc‐C6 PCa mouse model. In addition, periprostatic adipocytes directly stimulated MIC‐1 production from PC‐3 cells and IL‐8 secretion in prostate stromal fibroblasts through the upregulation of adipose lipolysis and free fatty acid release. The increased serum MIC‐1 was significantly correlated with human PCa stroma activation, high serum IL‐8, IL‐6, and lipase activity, advanced PCa progression, and high body mass index of the patients. Glial‐derived neurotrophic factor receptor α‐like (GFRAL), a specific receptor of MIC‐1, was highly expressed in both cytoplasm and membrane of PCa cells and surrounding stromal fibroblasts, and the expression level was decreased by androgen deprivation therapy and chemotherapy.

Conclusion

HFD‐mediated activation of the PCa stromal microenvironment through metabolically upregulated MIC‐1 signaling by increased available free fatty acids may be a critical mechanism of HFD and/or obesity‐induced PCa progression.

Challenges and Opportunities in Clinical Applications of Blood-Based Proteomics in Cancer

Simple Summary

The traditional approach in identifying cancer related protein biomarkers has focused on evaluation of a single peptide/protein in tissue or circulation. At best, this approach has had limited success for clinical applications, since multiple pathological tumor pathways may be involved during initiation or progression of cancer which diminishes the significance of a single candidate protein/peptide. Emerging sensitive proteomic based technologies like liquid chromatography mass spectrometry (LC-MS)-based quantitative proteomics can provide a platform for evaluating serial serum or plasma samples to interrogate secreted products of tumor–host interactions, thereby revealing a more “complete” repertoire of biological variables encompassing heterogeneous tumor biology. However, several challenges need to be met for successful application of serum/plasma based proteomics. These include uniform pre-analyte processing of specimens, sensitive and specific proteomic analytical platforms and adequate attention to study design during discovery phase followed by validation of discovery-level signatures for prognostic, predictive, and diagnostic cancer biomarker applications.

Abstract

Blood is a readily accessible biofluid containing a plethora of important proteins, nucleic acids, and metabolites that can be used as clinical diagnostic tools in diseases, including cancer. Like the on-going efforts for cancer biomarker discovery using the liquid biopsy detection of circulating cell-free and cell-based tumor nucleic acids, the circulatory proteome has been underexplored for clinical cancer biomarker applications. A comprehensive proteome analysis of human serum/plasma with high-quality data and compelling interpretation can potentially provide opportunities for understanding disease mechanisms, although several challenges will have to be met. Serum/plasma proteome biomarkers are present in very low abundance, and there is high complexity involved due to the heterogeneity of cancers, for which there is a compelling need to develop sensitive and specific proteomic technologies and analytical platforms. To date, liquid chromatography mass spectrometry (LC-MS)-based quantitative proteomics has been a dominant analytical workflow to discover new potential cancer biomarkers in serum/plasma. This review will summarize the opportunities of serum proteomics for clinical applications; the challenges in the discovery of novel biomarkers in serum/plasma; and current proteomic strategies in cancer research for the application of serum/plasma proteomics for clinical prognostic, predictive, and diagnostic applications, as well as for monitoring minimal residual disease after treatments. We will highlight some of the recent advances in MS-based proteomics technologies with appropriate sample collection, processing uniformity, study design, and data analysis, focusing on how these integrated workflows can identify novel potential cancer biomarkers for clinical applications.

Molecular insights into cancer drug resistance from a proteomics perspective

INTRODUCTION

Resistance to chemotherapy and development of specific and effective molecular targeted therapies are major obstacles facing current cancer treatment. Comparative proteomic approaches have been employed for the discovery of putative biomarkers associated with cancer drug resistance and have yielded a number of candidate proteins, showing great promise for both novel drug target identification and personalized medicine for the treatment of drug-resistant cancer. Areas covered: Herein, we review the recent advances and challenges in proteomics studies on cancer drug resistance with an emphasis on biomarker discovery, as well as understanding the interconnectivity of proteins in disease-related signaling pathways. In addition, we highlight the critical role that post-translational modifications (PTMs) play in the mechanisms of cancer drug resistance. Expert opinion: Revealing changes in proteome profiles and the role of PTMs in drug-resistant cancer is key to deciphering the mechanisms of treatment resistance. With the development of sensitive and specific mass spectrometry (MS)-based proteomics and related technologies, it is now possible to investigate in depth potential biomarkers and the molecular mechanisms of cancer drug resistance, assisting the development of individualized therapeutic strategies for cancer patients.

Glyceryl trinitrate‑induced cytotoxicity of docetaxel‑resistant prostatic cancer cells is associated with differential regulation of clusterin

Metastatic castration resistant prostate cancer (mCRPC) relapse due to acquired resistance to chemotherapy, such as docetaxel, remains a major threat to patient survival. Resistance of mCRPC to docetaxel can be associated with elevated levels of soluble clusterin (sCLU) and growth differentiation factor‑15 (GDF‑15). Any strategies aiming to modulate sCLU and/or GDF‑15 in docetaxel‑resistant prostate cancer cells present a therapeutic interest. The present study reports the cytotoxic effect of a nitric oxide donor, glyceryl trinitrate (GTN), on docetaxel‑resistant mCRPC human cell lines and demonstrates that GTN displays greater inhibition of cell viability toward docetaxel‑resistant mCRPC cells than on mCRPC cells. It is also demonstrated that GTN modulates the level of expression of clusterin (CLU) which is dependent of GDF‑15, two markers associated with docetaxel resistance in prostate cancer. The results indicate that GTN represses the level of expression of the cytoprotective isoform of CLU (sCLU) and can increase the level of expression of the cytotoxic isoform (nuclear CLU) in docetaxel resistant cells. Furthermore, it was observed that GTN differentially regulates the level of the precursor form of GDF‑15 between resistant and parental cells, and that recombinant GDF‑15 can modulate the expression of CLU isoforms and counteract GTN‑induced cytotoxicity in resistant cells. A link was established between GDF‑15 and the expression of CLU isoforms. The present study thus revealed GTN as a potential therapeutic strategy to overcome docetaxel‑resistant mCRPC.

Proteasome inhibition boosts autophagic degradation of ubiquitinated-AGR2 and enhances the antitumor efficiency of bevacizumab

Anterior gradient 2 (AGR2), a protein belonging to the protein disulfide isomerase (PDI) family, is overexpressed in multiple cancers and promotes angiogenesis to drive cancer progression. The mechanisms controlling AGR2 abundance in cancer remain largely unknown. Here, we observed that AGR2 expression is significantly suppressed by proteasome inhibitor MG132/bortezomib at mRNA and protein levels in lung cancer cells. MG132-mediated repression of AGR2 transcription was independent of ROS generation and ER stress induction, but partially resulted from the downregulated E2F1. Further investigation revealed that MG132 facilitated polyubiquitinated AGR2 degradation through activation of autophagy, as evidenced by predominant restoration of AGR2 level in cells genetic depletion of Atg5 and Atg7, or by autophagy inhibitors. Activation of autophagy by rapamycin noticeably reduced the AGR2 protein in cells and in the mouse tissue samples administrated with bortezomib. We also provided evidence identifying the K48-linked polyubiquitin chains conjugating onto K89 of AGR2 by an E3 ligase UBR5. In addition, an autophagy receptor NBR1 was demonstrated to be important in polyubiquitinated AGR2 clearance in response to MG132 or bortezomib. Importantly, downregulation of AGR2 by proteasome inhibition significantly enhanced antitumor activity of bevacizumab, highlighting the importance of AGR2 as a predictive marker for selection of subgroup patients in chemotherapy.

Chemotherapy and Inflammatory Cytokine Signalling in Cancer Cells and the Tumour Microenvironment

Cancer is the result of a cell's acquisition of a variety of biological capabilities or 'hallmarks' as outlined by Hanahan and Weinberg. These include sustained proliferative signalling, the ability to evade growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, and the ability to invade other tissue and metastasize. More recently, the ability to escape immune destruction has been recognized as another important hallmark of tumours. It is suggested that genome instability and inflammation accelerates the acquisition of a variety of the above hallmarks. Inflammation, is a product of the body's response to tissue damage or pathogen invasion. It is required for tissue repair and host defense, but prolonged inflammation can often be the cause for disease. In a cancer patient, it is often unclear whether inflammation plays a protective or deleterious role in disease progression. Chemotherapy drugs can suppress tumour growth but also induce pathways in tumour cells that have been shown experimentally to support tumour progression or, in other cases, encourage an anti-tumour immune response. Thus, with the goal of better understanding the context under which each of these possible outcomes occurs, recent progress exploring chemotherapy-induced inflammatory cytokine production and the effects of cytokines on drug efficacy in the tumour microenvironment will be reviewed. The implications of chemotherapy on host and tumour cytokine pathways and their effect on the treatment of cancer patients will also be discussed.

miR-217 sensitizes chronic myelogenous leukemia cells to tyrosine kinase inhibitors by targeting pro-oncogenic anterior gradient 2

BCR-ABL1-independent mechanisms had been thought to mediate drug resistance to tyrosine kinase inhibitors (TKIs) in patients with chronic myelogenous leukemia (CML). The pro-oncogenic anterior gradient 2 (AGR2) mediates drug resistance of cancer cells. In this study, we observed an increased level of AGR2 in TKI-resistant CML cells. Silence of AGR2 in dasatinib-resistant K562 (K562DR) cells led to restored sensitivity to dasatinib both in vitro and in vivo. Exposure to dasatinib induced upregulation of AGR2 in K562 cells, which indicated a probable treatment-related drug resistance. We further investigated the potential interaction between microRNA (miRNA) and AGR2 in K562DR cells and found that downregulation of miR-217 was associated with overexpression of AGR2 in K562DR cells. Luciferase reporter assay identified that miR-217 negatively regulated expression of AGR2 through binding the 3'-untranslated region of AGR2. Hypermethylation of the CpG island on the promoter region of the MIR217 gene is a probable reason for the downregulation of miR-217 in dasatinib-treated K562 cells. Forced expression of miR-217 led to decreased expression of AGR2 as well as compromised TKI-resistant potential of K562DR cells. Similarly, overexpression of miR-217 resensitized K562DR cells to dasatinib treatment in a murine xenograft transplantation model. TKI treatment-induced drug resistance is correlated with a decrease of miR-217 and upregulation of AGR2. The miR-217/AGR2 interaction might be a potential therapeutic target in treating CML patients with TKI resistance.

Promise and Implementation of Proteomic Prostate Cancer Biomarkers

Prostate cancer is one of the most commonly diagnosed malignancy and the fifth leading cause of cancer mortality in men. Despite the broad use of prostate-specific antigen test that resulted in an increase in number of diagnosed cases, disease management needs to be improved. Proteomic biomarkers alone and or in combination with clinical and pathological risk calculators are expected to improve on decreasing the unnecessary biopsies, stratify low risk patients, and predict response to treatment. To this end, significant efforts have been undertaken to identify novel biomarkers that can accurately discriminate between indolent and aggressive cancer forms and indicate those men at high risk for developing prostate cancer that require immediate treatment. In the era of “big data” and “personalized medicine” proteomics-based biomarkers hold great promise to provide clinically applicable tools, as proteins regulate all biological functions, and integrate genomic information with the environmental impact. In this review article, we aim to provide a critical assessment of the current proteomics-based biomarkers for prostate cancer and their actual clinical applicability. For that purpose, a systematic review of the literature published within the last 10 years was performed using the Web of Science Database. We specifically discuss the potential and prospects of use for diagnostic, prognostic and predictive proteomics-based biomarkers, including both body fluid- and tissue-based markers.

Matrix metalloproteinase 7, soluble Fas and Fas ligand serum levels for predicting docetaxel resistance and survival in castration-resistant prostate cancer

OBJECTIVE

To assess the predictive value of pre-chemotherapy matrix metalloproteinase 7 (MMP-7), soluble Fas (sFas) and Fas ligand (FasL) serum levels, as well as their changes during therapy.

PATIENTS AND METHODS

Serum levels of MMP-7, Fas and FasL were determined by ELISA in 96 patients with castration-resistant prostate cancer (CRPC): 21 docetaxel-resistant patients who received one single series and 75 docetaxel-sensitive patients who received repeated series of docetaxel. In addition to the 96 pretreatment serum samples, 987 sera collected during chemotherapy were also analysed.

RESULTS

Higher pretreatment serum MMP-7, sFas and prostate-specific antigen (PSA) levels were significantly associated with both docetaxel resistance (P = 0.007, P = 0.001, P < 0.001, respectively) and shorter cancer-specific survival (P < 0.001, P = 0.041, P < 0.001, respectively). High MMP-7 level remained an independent predictor of both docetaxel resistance (hazard ratio [HR] 2.298, 95% confidence interval [CI]: 1.354-3.899; P = 0.002) and poor cancer-specific survival (HR 2.11, 95% CI: 1.36-3.30; P = 0.001) in multivariable analyses. Greater increase in MMP-7 levels in the second treatment holiday and greater increase in PSA levels in the first and second treatment holidays were predictive of survival.

CONCLUSIONS

Pretreatment serum MMP-7 levels may help to select patients with CRPC who are likely to benefit from docetaxel chemotherapy. Furthermore, MMP-7 levels alone or in combination with PSA levels could be used for therapy monitoring. Correlative studies embedded in clinical trials are necessary to validate these biomarkers for clinical decision-making.

Elevated growth differentiating factor 15 expression predicts long-term benefit of docetaxel, cisplatin and 5-fluorouracil induction chemotherapy in patients with oral cancer

Our previous phase 3 trial (NCT01542931) failed to demonstrate improved survival when docetaxel, cisplatin and 5-fluorouracil (TPF) induction chemotherapy was introduced prior to surgery and postoperative radiotherapy in patients with locally advanced oral squamous cell carcinoma (OSCC). The aim of the present study was to investigate the long-term predictive value of GDF15 expression for potential personalized treatment strategies in OSCC. A total of 256 patients with stage III/IVA OSCC from our phase 3 trial were enrolled in the present study. Immunohistochemical staining against GDF15 was performed in the biopsy samples from 230/256 patients. Kaplan-Meier analysis, followed by the log-rank test, and the Cox proportional hazards model were used for outcome analysis using the statistical SPSS 18.0 software package for Windows. Among the 230 patients, low GDF15 expression was detected in 68 patients and high GDF15 expression was detected in 162 patients. With a median follow-up period of 67 months, the patients with low GDF15 expression exhibited a higher survival rate than those with high GDF15 expression, including 5-year overall survival (73.4 vs. 57.7%; P=0.059), 5-year disease-free survival (64.5 vs. 49.2%; P=0.033), 5-year locoregional recurrence-free survival (66.0 vs. 51.5%; P=0.043) and 5-year distant metastasis-free survival (73.4 vs. 56.6%; P=0.038) rates. Furthermore, the cT3/4N0M0 patients with high GDF15 expression benefited significantly from TPF induction chemotherapy, including overall survival (HR=0.233; P=0.02), disease-free survival (HR=0.296; P=0.014), locoregional recurrence-free survival (HR=0.347; P=0.035) and distant metastasis-free survival (HR=0.212; P=0.013) rates. The results of the present study suggested that elevated GDF15 expression may be used as a long-term prognostic biomarker for poor clinical outcomes in patients with locally advanced OSCC. Elevated GDF15 expression in cT3/4N0M0 patients predicts significant long-term benefit of survival from TPF induction chemotherapy.

Splicing of platelet resident pre-mRNAs upon activation by physiological stimuli results in functionally relevant proteome modifications

Platelet activation triggers thrombus formation in physiological and pathological conditions, such as acute coronary syndromes. Current therapies still fail to prevent thrombotic events in numerous patients, indicating that the mechanisms modulating platelet response during activation need to be clarified. The evidence that platelets are capable of de novo protein synthesis in response to stimuli raised the issue of how megakaryocyte-derived mRNAs are regulated in these anucleate cell fragments. Proteogenomics was applied here to investigate this phenomeon in platelets activated in vitro with Collagen or Thrombin Receptor Activating Peptide. Combining proteomics and transcriptomics allowed in depth platelet proteome characterization, revealing a significant effect of either stimulus on proteome composition. In silico analysis revealed the presence of resident immature RNAs in resting platelets, characterized by retained introns, while unbiased proteogenomics correlated intron removal by RNA splicing with changes on proteome composition upon activation. This allowed identification of a set of transcripts undergoing maturation by intron removal during activation and resulting in accumulation of the corresponding peptides at exon-exon junctions. These results indicate that RNA splicing events occur in platelets during activation and that maturation of specific pre-mRNAs is part of the activation cascade, contributing to a dynamic fine-tuning of the transcriptome.

Duration of response to first androgen deprivation therapy, time to castration resistance prostate cancer, and outcome of metastatic castration resistance prostate cancer patients treated with abiraterone acetate

Abiraterone acetate (AA) demonstrated its efficacy in the treatment of patients with metastatic castration resistance prostate cancer (mCRPC) in predocetaxel and postdocetaxel setting. However, we learn from pivotal studies that forms of primary and acquired resistance to this drug exist. Patient selection becomes so crucial to optimize treatment results. Potential predictive biomarkers have been identified but are not yet validated. In this scenario, clinical features and disease characteristics may still be of value in selecting patients for different treatments. The objective of this retrospective study was to assess whether or not a correlation between duration of response to first androgen deprivation therapy (ADT), time to castration-resistant prostate cancer (TTCRPC), and outcome of AA therapy exists. A retrospective analysis of clinical data of mCRPC patients treated with AA at two Italian cancer centers was carried out. The Kaplan-Meier method and Cox proportional hazard model were used to analyze survival data. Correlation between median duration of response to first ADT or median TTCRPC and the outcome of patients treated with AA was analyzed. From January 2015 to November 2015, data of 59 patients with mCRPC were collected. We observed no differences in patient's median progression-free survival (PFS) and biochemical progression-free survival (bPFS), according to both median duration of response to first-line ADT (duration of first ADT<13 months: median PFS and bPFS were 11 and 5 months, respectively; duration of ADT≥13 months: median PFS and bPFS were 9 and 6 months, respectively) and median TTCRPC (TTCRPC<28 months: median PFS and bPFS were 8 and 5 months, respectively; TTCRPC≥28 months: median PFS and bPFS were 10 and 9 months, respectively). Overall survival, in the same group, did not differ between patients with a duration of response to first ADT over or under 13 months (P=0.90) but in patients with a TTCRPC of 28 months or more, there was a trend toward longer survival than patients with TTCRPC less than 28 months (5-year overall survival was 74 vs. 50%; P=0.14). The duration of response to first-line ADT and the TTCRPC showed no significant association with outcome of AA therapy in patients with mCRPC. However, large prospective trials are desirable to confirm these data.

Generation of Prostate Cancer Cell Models of Resistance to the Anti-mitotic Agent Docetaxel

Microtubule targeting agents (MTAs) are a mainstay in the treatment of a wide range of tumors. However, acquired resistance to chemotherapeutic drugs is a common mechanism of disease progression and a prognostic-determinant feature of malignant tumors. In prostate cancer (PC), resistance to MTAs such as the taxane Docetaxel dictates treatment failure as well as progression towards lethal stages of disease that are defined by a poor prognosis and high mortality rates. Though studied for decades, the array of mechanisms contributing to acquired resistance are not completely understood, and thus pose a significant limitation to the development of new therapeutic strategies that could benefit patients in these advanced stages of disease. In this protocol, we describe the generation of Docetaxel-resistant prostate cancer cell lines that mimic lethal features of late-stage prostate cancer, and therefore can be used to study the mechanisms by which acquired chemoresistance arises. Despite potential limitations intrinsic to a cell based model, such as the loss of resistance properties over time, the Docetaxel-resistant cell lines produced by this method have been successfully used in recent studies and offer the opportunity to advance our molecular understanding of acquired chemoresistance in lethal prostate cancer.

Ginger Phytochemicals Inhibit Cell Growth and Modulate Drug Resistance Factors in Docetaxel Resistant Prostate Cancer Cell

Ginger has many bioactive compounds with pharmacological activities. However, few studies are known about these bioactive compounds activity in chemoresistant cells. The aim of the present study was to investigate the anticancer properties of ginger phytochemicals in docetaxel-resistant human prostate cancer cells in vitro. In this study, we isolated 6-gingerol, 10-gingerol, 4-shogaol, 6-shogaol, 10-shogaol, and 6-dehydrogingerdione from ginger. Further, the antiproliferation activity of these compounds was examined in docetaxel-resistant (PC3R) and sensitive (PC3) human prostate cancer cell lines. 6-gingerol, 10-gingerol, 6-shogaol, and 10-shogaol at the concentration of 100 μM significantly inhibited the proliferation in PC3R but 6-gingerol, 6-shogaol, and 10-shogaol displayed similar activity in PC3. The protein expression of multidrug resistance associated protein 1 (MRP1) and glutathione-S-transferase (GSTπ) is higher in PC3R than in PC3. In summary, we isolated the bioactive compounds from ginger. Our results showed that 6-gingerol, 10-gingerol, 6-shogaol, and 10-shogaol inhibit the proliferation of PC3R cells through the downregulation of MRP1 and GSTπ protein expression.

Prostate cancer proteomics: Current trends and future perspectives for biomarker discovery

The clinical and fundamental research in prostate cancer - the most common urological cancer in men - is currently entering the proteomic and genomic era. The focus has switched from one single marker (PSA) to panels of biomarkers (including proteins involved in ribosomal function and heat shock proteins). Novel genetic markers (such as Transmembrane protease serine 2 (TMPRSS2)-ERG fusion gene mRNA) or prostate cancer gene 3 (PCA3) had already entered the clinical practice, raising the question whether subsequent protein changes impact the evolution of the disease and the response to treatment. Proteomic technologies such as MALDI-MS, SELDI-MS, i-TRAQ allow a qualitative/quantitative analysis of the proteome variations, in both serum and tumor tissue. A new trend in prostate cancer research is proteomic analysis of prostasomes (prostate-specific exosomes), for the discovery of new biomarkers. This paper provides an update of novel clinical tests used in research and clinical diagnostic, as well as of potential tissue or fluid biomarkers provided by extensive proteomic research data.

Comprehensive Proteome Profiling of Platelet Identified a Protein Profile Predictive of Responses to An Antiplatelet Agent Sarpogrelate

Sarpogrelate is an antiplatelet agent widely used to treat arterial occlusive diseases. Evaluation of platelet aggregation is essential to monitor therapeutic effects of sarpogrelate. Currently, no molecular signatures are available to evaluate platelet aggregation. Here, we performed comprehensive proteome profiling of platelets collected from 18 subjects before and after sarpogrelate administration using LC-MS/MS analysis coupled with extensive fractionation. Of 5423 proteins detected, we identified 499 proteins affected by sarpogrelate and found that they strongly represented cellular processes related to platelet activation and aggregation, including cell activation, coagulation, and vesicle-mediated transports. Based on the network model of the proteins involved in these processes, we selected three proteins (cut-like homeobox 1; coagulation factor XIII, B polypeptide; and peptidylprolyl isomerase D) that reflect the platelet aggregation-related processes after confirming their alterations by sarpogrelate in independent samples using Western blotting. Our proteomic approach provided a protein profile predictive of therapeutic effects of sarpogrelate.

Macrophage Inhibitory Cytokine-1 as a Novel Diagnostic and Prognostic Biomarker in Stage I and II Nonsmall Cell Lung Cancer

BACKGROUND

Increased level of serum macrophage inhibitory cytokine-1 (MIC-1), a member of transforming growth factor-μ superfamily, was found in patients with epithelial tumors. This study aimed to evaluate whether serum level of MIC-1 can be a candidate diagnostic and prognostic indicator for early-stage nonsmall cell lung cancer (NSCLC).

METHODS

A prospective study enrolled 152 patients with Stage I-II NSCLC, who were followed up after surgical resection. Forty-eight patients with benign pulmonary disease (BPD) and 105 healthy controls were also included in the study. Serum MIC-1 levels were measured using an enzyme-linked immunosorbent assay, and the association with clinical and prognostic features was analyzed.

RESULTS

In patients with NSCLC, serum protein levels of MIC-1 were significantly increased compared with healthy controls and BPD patients (all P< 0.001). A threshold of 1000 pg/ml of MIC-1 was found in patients with early-stage (Stage I and II) NSCLC, with sensitivity and specificity of 70.4% and 99.0%, respectively. The serum levels of MIC-1 were associated with age (P = 0.001), gender (P = 0.030), and T stage (P = 0.022). Serum MIC-1 threshold of 1465 pg/ml was found in patients with poor early outcome, with sensitivity and specificity of 72.2% and 66.1%, respectively. The overall 3-year survival rate of NSCLC patients with high serum levels of MIC-1 (≥1465 pg/ml) was lower than that of NSCLC patients with low serum MIC-1 levels (77.6% vs. 94.8%). Multivariate Cox regression survival analysis showed that a high serum level of MIC-1 was an independent risk factor for reduced overall survival (hazard ratio = 3.37, 95% confidential interval: 1.09-10.42, P= 0.035).

CONCLUSION

The present study suggested that serum MIC-1 may be a potential diagnostic and prognostic biomarker for patients with early-stage NSCLC.

Persistent Neutrophil to Lymphocyte Ratio >3 during Treatment with Enzalutamide and Clinical Outcome in Patients with Castration-Resistant Prostate Cancer

The baseline value of neutrophil to lymphocyte ratio (NLR) has been found to be prognostic in patients with metastatic castration resistant prostate cancer (CRPC). We evaluated the impact of baseline NLR and its change in patients receiving enzalutamide. We included consecutive metastatic CRPC patients treated with enzalutamide after docetaxel and studies the change of NLR (>3 vs ≤3) after week 4 and 12 weeks. Progression-free survival (PFS), overall survival (OS) and their 95% Confidence Intervals (95% CI) were estimated by the Kaplan-Meier method and compared with the log-rank test. The impact of NLR on PFS and OS was evaluated by Cox regression analyses and on prostate-specific antigen response rates (PSA RR; PSA decline >50%) were evaluated by binary logistic regression. Data collected on 193 patients from 9 centers were evaluated. Median age was 73.1 years (range, 42.8–90.7). The median baseline NLR was 3.2. The median PFS was 3.2 months (95% CI = 2.7–4.2) in patients with baseline NLR >3 and 7.4 months (95% CI = 5.5–9.7) in those with NLR ≤3, p < 0.0001. The median OS was 10.4 months (95% CI = 6.5–14.9) in patients with baseline NLR >3 and 16.9 months (95% CI = 11.2–20.9) in those with baseline NLR ≤3, p < 0.0001. In multivariate analysis, changes in NLR at 4 weeks were significant predictors of both PFS [hazard ratio (HR) 1.24, 95% confidence interval (95% CI) 1.07–1.42, p = 0.003, and OS (HR 1.29, 95% CI 1.10–1.51, p = 0.001. A persistent NLR >3 during treatment with enzalutamide seems to have both prognostic and predictive value in CRPC patients.

LC-MS analysis of Hep-2 and Hek-293 cell lines treated with Brazilian red propolis reveals differences in protein expression

Objective

Red propolis, an exclusive variety of propolis found in the northeast of Brazil has shown to present antitumour activity, among several other biological properties. This article aimed to help to evaluate the underlying molecular mechanisms of the potential anticancer effects of red propolis on tumour, Hep-2, and non-tumour cells, Hek-293.

Methods

Differentially expressed proteins in human cell lines were identified through label-free quantitative MS-based proteomic platform, and cells were stained with Giemsa to show morphological changes.

Key findings

A total of 1336 and 773 proteins were identified for Hep-2 and Hek-293, respectively. Among the proteins here identified, 16 were regulated in the Hep-2 cell line and 04 proteins in the Hek-293 line. Over a total of 2000 proteins were identified under MS analysis, and approximately 1% presented differential expression patterns. The GO annotation using Protein Analysis THrough Evolutionary Relationships classification system revealed predominant molecular function of catalytic activity, and among the biological processes, the most prominent was associated to cell metabolism.

Conclusion

The proteomic profile here presented should help to elucidate further molecular mechanisms involved in inhibition of cancer cell proliferation by red propolis, which remain unclear to date.

Growth differentiation factor 15 is a promising diagnostic and prognostic biomarker in colorectal cancer

Although various studies have demonstrated that growth differentiation factor 15 (GDF15) might be a potential diagnostic and prognostic marker in colorectal cancer (CRC) patients, the results are inconsistent and the statistical power of individual studies is also insufficient. An original study was conducted to explore the diagnostic and prognostic value of serum GDF15 in CRC patients. We also conducted a meta‐analysis study which aimed to summarize the diagnostic and prognostic performance of serum GDF15 in CRC. We searched PubMed and ISI Web of Knowledge up to 1 November 2014 for eligible studies. In order to explore the diagnostic performance of GDF15, standardized mean difference (SMD) and their 95% confidence intervals (CI) were estimated and receiver‐operating characteristic (ROC) curves were constructed. For prognostic meta‐analysis, study‐specific hazard ratios (HRs) of serum GDF15 for survival were summarized. A total of eight studies were included in the meta‐analyses. Our results revealed that serum GDF15 levels in CRC patients were higher than those in healthy controls (SMD = 1.08, 95% CI: 0.56–1.59, P < 0.001). For discriminating CRC from healthy controls, the AUC of GDF15 was 0.816 (95% CI: 0.792–0.838). The sensitivity and specificity were 58.9% (95% CI: 55.0–62.8) and 92.08% (95% CI: 89.2–94.4), respectively, when a cut‐off value of 1099 pg/ml was established. Besides, higher GDF15 expression level was associated with worse overall survival for CRC patients (pooled HR = 2.09, 95% CI: 1.47–2.96). In conclusion, the present meta‐analysis suggests that serum GDF15 may be a useful diagnostic and prognostic biomarker for CRC.

Cytokine profiling of docetaxel-resistant castration-resistant prostate cancer

Background:

Docetaxel improves symptoms and survival in metastatic castration-resistant prostate cancer (CRPC). However, ∼50% of patients are chemoresistant. This study examined whether changes in cytokine levels predict for docetaxel resistance in vitro and in a clinical cohort.

Methods:

PC3 cells or their docetaxel-resistant subline (PC3Rx) were co-cultured with U937 monocytes, with and without docetaxel treatment, and cytokine levels were measured. The circulating levels of 28 cytokines were measured pre-/post cycle 1 of docetaxel from 55 men with CRPC, and compared with prostate-specific antigen (PSA) response.

Results:

PC3Rx-U937 co-culture expressed more cytokines, chiefly markers of alternative macrophage differentiation, compared with PC3-U937 co-culture. Docetaxel treatment enhanced cytokine production by PC3Rx-U937 co-culture, while reducing cytokine levels in PC3-U937. In patients, changes in the levels of seven circulating cytokines (macrophage inhibitory cytokine 1 (MIC1), interleukin (IL)-1ra, IL-1β, IL-4, IL-6, IL-12 and IFNγ) after cycle 1 of docetaxel were associated with progressive disease (all P<0.05). The combination of changes in MIC1, IL-4 and IL-6 most strongly predicted PSA response (P=0.002).

Conclusions:

In vitro studies suggest docetaxel resistance is mediated, at least in part, by cytokines induced by the interaction between the docetaxel-resistant tumour cells and macrophages. Early changes in circulating cytokine levels were associated with docetaxel resistance in CRPC patients. When considered together, these data suggest a significant role for the inflammatory response and macrophages in the development of docetaxel resistance in CRPC.

Absolute quantification of DcR3 and GDF15 from human serum by LC-ESI MS

Biomarkers are widely used in clinical diagnosis, prognosis and therapy monitoring. Here, we developed a protocol for the efficient and selective enrichment of small and low concentrated biomarkers from human serum, involving a 95% effective depletion of high-abundant serum proteins by partial denaturation and enrichment of low-abundant biomarkers by size exclusion chromatography. The recovery of low-abundance biomarkers was above 97%. Using this protocol, we quantified the tumour markers DcR3 and growth/differentiation factor (GDF)15 from 100 μl human serum by isotope dilution mass spectrometry, using ¹⁵N metabolically labelled and concatamerized fingerprint peptides for the both proteins. Analysis of three different fingerprint peptides for each protein by liquid chromatography electrospray ionization mass spectrometry resulted in comparable concentrations in three healthy human serum samples (DcR3: 27.23 ± 2.49 fmol/ml; GDF15: 98.11 ± 0.49 fmol/ml). In contrast, serum levels were significantly elevated in tumour patients for DcR3 (116.94 ± 57.37 fmol/ml) and GDF15 (164.44 ± 79.31 fmol/ml). Obtained data were in good agreement with ELISA and qPCR measurements, as well as with literature data. In summary, our protocol allows the reliable quantification of biomarkers, shows a higher resolution at low biomarker concentrations than antibody-based strategies, and offers the possibility of multiplexing. Our proof-of-principle studies in patient sera encourage the future analysis of the prognostic value of DcR3 and GDF15 for colon cancer patients in larger patient cohorts.

Combination therapy of prostate cancer with HPMA copolymer conjugates containing PI3K/mTOR inhibitor and docetaxel

Combination therapies have been investigated to address the current challenges of anti-cancer therapeutics. In particular, a novel paradigm of combination therapy targeting both cancer stem/progenitor cells and bulk tumor cells is promising to improve the long-term therapeutic benefit against prostate cancer. Among the therapeutic agents with anti-CSC activities, the PI3K/mTOR inhibitors exhibit preferential inhibitory effect on prostate cancer stem/progenitor cells and potent cytotoxicity against bulk tumor cells. The combination of PI3K/mTOR inhibitor and traditional chemotherapy docetaxel may show superior therapeutic effect over single drug treatment. Aiming to further improve the combinational anti-tumor and anti-CSC effect, we developed the combination therapy containing two HPMA copolymer-drug conjugates, incorporated with PI3K/mTOR inhibitor GDC-0980 (P-(GDC-0980)) and docetaxel (P-DTX), respectively. The anti-tumor and anti-CSC effects of the single and combination therapy were investigated in vitro and on PC-3 prostate cancer xenografts in nude mice. Our evaluations showed that P-(GDC-0980) suppressed CD133+ prostate stem/progenitor cell growth even at the low dose which does not cause significant growth inhibition in bulk tumor cells. The combination therapy exhibited effective anti-CSC effect as well as enhanced anti-bulk tumor effect in vitro. Among all the single and combination dosing regimens of free drugs and conjugates, the macromolecular combination therapy showed significantly prolonged mice survival in vivo.

Knockdown of platinum-induced growth differentiation factor 15 abrogates p27-mediated tumor growth delay in the chemoresistant ovarian cancer model A2780cis

Molecular mechanisms underlying the development of resistance to platinum-based treatment in patients with ovarian cancer remain poorly understood. This is mainly due to the lack of appropriate in vivo models allowing the identification of resistance-related factors. In this study, we used human whole-genome microarrays and linear model analysis to identify potential resistance-related genes by comparing the expression profiles of the parental human ovarian cancer model A2780 and its platinum-resistant variant A2780cis before and after carboplatin treatment in vivo. Growth differentiation factor 15 (GDF15) was identified as one of five potential resistance-related genes in the A2780cis tumor model. Although A2780-bearing mice showed a strong carboplatin-induced increase of GDF15 plasma levels, the basal higher GDF15 plasma levels of A2780cis-bearing mice showed no further increase after short-term or long-term carboplatin treatment. This correlated with a decreased DNA damage response, enhanced AKT survival signaling and abrogated cell cycle arrest in the carboplatin-treated A2780cis tumors. Furthermore, knockdown of GDF15 in A2780cis cells did not alter cell proliferation but enhanced cell migration and colony size in vitro. Interestingly, in vivo knockdown of GDF15 in the A2780cis model led to a basal-enhanced tumor growth, but increased sensitivity to carboplatin treatment as compared to the control-transduced A2780cis tumors. This was associated with larger necrotic areas, a lobular tumor structure and increased p53 and p16 expression of the carboplatin-treated shGDF15-A2780cis tumors. Furthermore, shRNA-mediated GDF15 knockdown abrogated p27 expression as compared to control-transduced A2780cis tumors. In conclusion, these data show that GDF15 may contribute to carboplatin resistance by suppressing tumor growth through p27. These data show that GDF15 might serve as a novel treatment target in women with platinum-resistant ovarian cancer.

Cytotoxic chemotherapy in the contemporary management of metastatic castration-resistant prostate cancer (mCRPC)

For several years, docetaxel was the only treatment shown to improve survival of patients with metastatic castration-resistant prostate cancer (mCRPC). There are now several novel agents available, although chemotherapy with docetaxel and cabazitaxel continues to play an important role. However, the increasing number of available agents will inevitably affect the timing of chemotherapy and therefore it may be important to offer this approach before declining performance status renders patients ineligible for chemotherapy. Patient selection is also important to optimise treatment benefit. The role of predictive biomarkers has assumed greater importance due to the development of multiple agents and resistance to available agents. In addition, the optimal sequence of treatments remains undefined and requires further study in order to maximize long-term outcomes. We provide an overview of the clinical data supporting the role of chemotherapy in the treatment of mCRPC and the emerging role in metastatic castration-sensitive prostate cancer. We review the key issues in the management of patients including selection of patients for chemotherapy, when to start chemotherapy, and how best to sequence treatments to maximise outcomes. In addition, we briefly summarise the promising new chemotherapeutic agents in development in the context of emerging therapies.

Nuclear Eg5 (kinesin spindle protein) expression predicts docetaxel response and prostate cancer aggressiveness

Novel biomarkers predicting prostate cancer (PCa) aggressiveness and docetaxel therapy response of PCa patients are needed. In this study the correlation between nuclear Eg5-expression, PCa docetaxel response and PCa aggressiveness was assessed. Immunohistochemical staining for nuclear Eg5 was performed on 117 archival specimens from 110 PCa patients treated with docetaxel between 2004 and 2012. Samples were histologically categorized as positive/negative. Median follow-up time from diagnosis was 11.6 years. Nuclear Eg5-expression was significantly related to docetaxel response (p=0.036) in tissues acquired within three years before docetaxel initiation. Nuclear Eg5-expression was not related to Gleason-score (p=0.994). Survival of patients after docetaxel initiation did not differ based on nuclear Eg5-expression (p=0.540). Analyzing samples taken before hormonal therapy, overall survival and time to docetaxel use were significantly decreased in patients with nuclear Eg5-expressing tumors (p<0.01). Eg5-positive nuclei were found more frequently in T4-staged tumors (p=0.04), Gleason 8-10 tumors (p=0.08), and in metastasized tumors (p<0.01). Multivariate analyses indicated that nuclear Eg5-expression may be an independent parameter for tumor aggressiveness. Limitations of a retrospective analysis apply. In conclusion, nuclear Eg5-expression may be a predictive biomarker for docetaxel response in metastatic castrate-resistant PCa patients and a prognostic biomarker for hormone-naive PCa patients. Prospective validation studies are needed.

Local and systemic protumorigenic effects of cancer-associated fibroblast-derived GDF15

The tumor stroma is vital to tumor development, progression, and metastasis. Cancer-associated fibroblasts (CAF) are among the abundant cell types in the tumor stroma, but the range of their contributions to cancer pathogenicity has yet to be fully understood. Here, we report a critical role for upregulation of the TGFβ/BMP family member GDF15 (MIC-1) in tumor stroma. GDF15 was found upregulated in situ and in primary cultures of CAF from prostate cancer. Ectopic expression of GDF15 in fibroblasts produced prominent paracrine effects on prostate cancer cell migration, invasion, and tumor growth. Notably, GDF15-expressing fibroblasts exerted systemic in vivo effects on the outgrowth of distant and otherwise indolent prostate cancer cells. Our findings identify tumor stromal cells as a novel source of GDF15 in human prostate cancer and illustrate a systemic mechanism of cancer progression driven by the tumor microenvironment. Further, they provide a functional basis to understand GDF15 as a biomarker of poor prognosis and a candidate therapeutic target in prostate cancer.

Circulating microRNAs are associated with docetaxel chemotherapy outcome in castration-resistant prostate cancer

Background:

Docetaxel is the first-line chemotherapy for castration-resistant prostate cancer (CRPC). However, response rates are ∼50% and determined quite late in the treatment schedule, thus non-responders are subjected to unnecessary toxicity. The potential of circulating microRNAs as early biomarkers of docetaxel response in CRPC patients was investigated in this study.

Methods:

Global microRNA profiling was performed on docetaxel-resistant and sensitive cell lines to identify candidate circulating microRNA biomarkers. Custom Taqman Array MicroRNA cards were used to measure the levels of 46 candidate microRNAs in plasma/serum samples, collected before and after docetaxel treatment, from 97 CRPC patients.

Results:

Fourteen microRNAs were associated with serum prostate-specific antigen (PSA) response or overall survival, according to Mann–Whitney U or log-rank tests. Non-responders to docetaxel and patients with shorter survival generally had high pre-docetaxel levels of miR-200 family members or decreased/unchanged post-docetaxel levels of miR-17 family members. Multivariate Cox regression with bootstrapping validation showed that pre-docetaxel miR-200b levels, post-docetaxel change in miR-20a levels, pre-docetaxel haemoglobin levels and visceral metastasis were independent predictors of overall survival when modelled together.

Conclusions:

Our study suggests that circulating microRNAs are potential early predictors of docetaxel chemotherapy outcome, and warrant further investigation in clinical trials.

Anti-inflammatory effect of Marchantin M contributes to sensitization of prostate cancer cells to docetaxel

As pro-inflammatory cytokines and chemokines contribute to the malignancy of many types of human cancer, we examined the anti-inflammatory effect of bisbibenzyls, a diverse bioactive group of naturally occurring compounds. Marchantin M (Mar M) was identified through a screening process of these compounds as a potent anti-inflammatory agent based on its capacity to inhibit LPS-induced IL6, IL1β and CCL2 expression in HUVECs and PBMCs without affecting cell proliferation. Since Mar M has been found to exhibit anticancer activity, we observed that Mar M treatment also resulted in decreases in the expressions of IL6, IL1β and TNFα in metastatic prostate cancer (PCa) cells. This effect was further confirmed in other cancer cell lines that express high level of pro-inflammatory cytokines. Furthermore, inactivation of NF-κB, a critical transcription factor controlling many pro-inflammatory cytokine expressions, was observed in Mar M-treated PCa cells as evidenced by decreased phosphor-p65 and subsequently phosphor-STAT3. Mar M also suppressed phosphorylation of IKBα, an inhibitor of NF-κB in the cytosol. However, reduced phosphor-p65 by Mar M was slightly increased when knockdown of IKBα, suggesting that Mar M may target upstream molecules of IKBα/NF-κB signaling. Finally, treatment with Mar M resulted in more enhanced-sensitivity of PCa cells to docetaxel-induced apoptosis than that of the IL6 blocking. Our study demonstrates the potential of the anti-inflammatory agent Mar M as an adjuvant to improve the efficacy of traditional anticancer agents such as docetaxel.

GDF15 is a potential predictive biomarker for TPF induction chemotherapy and promotes tumorigenesis and progression in oral squamous cell carcinoma

BACKGROUND

Randomized trials have not shown major survival benefits when induction chemotherapy plus standard therapy is compared with standard therapy alone in patients with oral squamous cell carcinoma (OSCC). Induction chemotherapy is likely to be effective for biologically distinct subgroups and biomarker development may lead to identification of patients whose tumors are likely to respond to a particular treatment.

PATIENTS AND METHODS

We evaluated immunohistochemical staining for GDF15 in pretreatment biopsy specimens of 230 of 256 OSCC patients who were treated in a prospective, randomized, phase III trial on induction chemotherapy including docetaxel, cisplatin and 5-fluorouracil (TPF). Relationship between GDF15 intervention and cell proliferation, migration, invasion, colony formation and tumorigenicity was analyzed using in vitro and in vivo OSCC models.

RESULTS

Low GDF15 expression predicted a better survival in OSCC patients, especially overall survival [P = 0.049, hazard ratio (HR) = 0.597] and distant metastasis-free survival (DMFS; P = 0.031, HR = 0.562). cN+ patients with low GDF15 expression benefitted from induction TPF in overall survival (P = 0.039, HR = 0.247) and DMFS (P = 0.039, HR = 0.247), cN- patients with high GDF15 expression benefitted from induction TPF in overall survival (P = 0.019, HR = 0.231), disease-free survival (P = 0.011, HR = 0.281), locoregional recurrence-free survival (P = 0.035, HR = 0.347) and DMFS (P = 0.009, HR = 0.197). Decreased GDF15 expression in OSCC lines significantly inhibited cell proliferation, migration, invasion, colony formation and tumorigenesis through increased phosphorylation of AKT and ERK1/2 (P < 0.05). Likewise, overexpression of GDF15 significantly promoted cell proliferation, migration, invasion and colony formation through decreased phosphorylation of AKT and ERK1/2 (P < 0.05).

CONCLUSIONS

GDF15 expression can be used as a prognostic biomarker for OSCC, and as a predictive biomarker for benefitting from TPF induction chemotherapy. GDF15 promotes tumorigenesis and progression through phosphorylation of AKT and ERK1/2 in OSCC. The clinical trial in this study was registered with www.ClinicalTrials.gov (NCT01542931).

Diagnostic performance of serum macrophage inhibitory cytokine-1 in pancreatic cancer: a meta-analysis and meta-regression analysis

Many existing studies have demonstrated that the macrophage inhibitory cytokine-1 (MIC-1) might be a powerful diagnostic biomarker in patients with pancreatic cancer; but individually published results are inconclusive. This meta-analysis aimed to derive a more precise estimation of the diagnostic performance of serum MIC-1 in pancreatic cancer. We searched CISCOM, CINAHL, Web of Science, PubMed, Google Scholar, EBSCO, Cochrane Library, China BioMedicine (CBM), and China National Knowledge Infrastructure (CNKI) databases from their inception through August 1st, 2013. Meta-analysis was performed using Meta-Disc version 1.4 and STATA version 12.0 software. Crude standardized mean difference (SMD) and their 95% confidence intervals (CI) were estimated. Data from selected studies were pooled to yield summary sensitivity, specificity, positive and negative likelihood ratio (LR), diagnostic odds ratio (DOR), and receiver operating characteristic (SROC) curve. Ten case-control studies were included in this meta-analysis with a total of 1235 pancreatic cancer patients and 730 healthy subjects. Our meta-analysis results revealed that serum MIC-1 levels in pancreatic patients were higher than those of healthy subjects (SMD=1.38, 95% CI=1.15-1.62, p<0.001). The area under the SROC curve was 0.92 (SE=0.020); the pooled sensitivity was 0.79 (95% CI=0.77-0.82); and the pooled specificity was 0.86 (95% CI=0.84-0.88). The pooled positive LR was 6.20 (95% CI=1.24-30.91); the pooled DOR was 35.73 (95% CI=18.52-68.93). In conclusion, the present meta-analysis suggests that serum MIC-1 may be a useful diagnostic biomarker with high sensitivity and specificity for identifying pancreatic cancer.

Morphological effects on expression of growth differentiation factor 15 (GDF15), a marker of metastasis

Cancer cells typically demonstrate altered morphology during the various stages of disease progression as well as metastasis. While much is known about how altered cell morphology in cancer is a result of genetic regulation, less is known about how changes in cell morphology affect cell function by influencing gene expression. In this study, we altered cell morphology in different types of cancer cells by disrupting the actin cytoskeleton or by modulating attachment and observed a rapid up-regulation of growth differentiation factor 15 (GDF15), a member of the transforming growth factor-beta (TGF-β) super-family. Strikingly, this up-regulation was sustained as long as the cell morphology remained altered but was reversed upon allowing cell morphology to return to its typical configuration. The potential significance of these findings was examined in vivo using a mouse model: a small number of cancer cells grown in diffusion chambers that altered morphology increased mouse serum GDF15. Taken together, we propose that during the process of metastasis, cancer cells experience changes in cell morphology, resulting in the increased production and secretion of GDF15 into the surrounding environment. This indicates a possible relationship between serum GDF15 levels and circulating tumor cells may exist. Further investigation into the exact nature of this relationship is warranted.