ABCC5 supports osteoclast formation and promotes breast cancer metastasis to bone

Multiple influence of immune cells in the bone metastatic cancer microenvironment on tumors

Bone is a common organ for solid tumor metastasis. Malignant bone tumor becomes insensitive to systemic therapy after colonization, followed by poor prognosis and high relapse rate. Immune and bone cells in situ constitute a unique immune microenvironment, which plays a crucial role in the context of bone metastasis. This review firstly focuses on lymphatic cells in bone metastatic cancer, including their function in tumor dissemination, invasion, growth and possible cytotoxicity-induced eradication. Subsequently, we examine myeloid cells, namely macrophages, myeloid-derived suppressor cells, dendritic cells, and megakaryocytes, evaluating their interaction with cytotoxic T lymphocytes and contribution to bone metastasis. As important components of skeletal tissue, osteoclasts and osteoblasts derived from bone marrow stromal cells, engaging in 'vicious cycle' accelerate osteolytic bone metastasis. We also explain the concept tumor dormancy and investigate underlying role of immune microenvironment on it. Additionally, a thorough review of emerging treatments for bone metastatic malignancy in clinical research, especially immunotherapy, is presented, indicating current challenges and opportunities in research and development of bone metastasis therapies.

Multidrug resistance protein 5 affects cell proliferation, migration and gemcitabine sensitivity in pancreatic cancer MIA Paca‑2 and PANC‑1 cells

Gemcitabine‑based chemotherapy has been widely adopted as the standard and preferred chemotherapy regimen for treating advanced pancreatic cancer. However, the contribution of multidrug resistance protein 5 (MRP5) to gemcitabine resistance and pancreatic cancer progression remains controversial. In the present study, the effect of silencing MRP5 on gemcitabine resistance and cell proliferation and migration of human pancreatic cancer MIA Paca‑2 and PANC‑1 cells was investigated by using short‑hairpin RNA delivered by lentiviral vector transduction. The knockdown of MRP5 was confirmed on both mRNA and protein levels using qPCR and surface staining assays, respectively. MRP5‑regulated gemcitabine sensitivity was assessed by MTT, PrestoBlue and apoptosis assays. The effect of MRP5 on pancreatic cancer cell proliferation and migration was determined using colony‑formation, wound‑healing and Transwell migration assays. The interaction of gemcitabine and cyclic guanosine monophosphate (cGMP) with MRP5 protein was explored using molecular docking. The results indicated that the MRP5 mRNA and protein levels were significantly reduced in all the MIA Paca‑2 and PANC‑1 clones. MRP5 affected gemcitabine cytotoxicity and the rate of gemcitabine‑induced apoptosis. Silencing MRP5 decreased cell proliferation and migration in both MIA Paca‑2 and PANC‑1 cells. Docking studies showed high binding affinity of cGMP towards MRP5, indicating the potential of MRP5‑mediated cGMP accumulation in the microenvironment. In conclusion, MRP5 has an important role in cancer proliferation and migration in addition to its drug efflux functions in two widely available pancreatic tumour cell lines (MIA Paca‑2 and PANC‑1).

MRI-based breast cancer radiogenomics using RNA profiling: association with subtypes in a single-center prospective study

BACKGROUND

There are few prospective studies on the correlations between MRI features and whole RNA-sequencing data in breast cancer according to molecular subtypes. The purpose of our study was to explore the association between genetic profiles and MRI phenotypes of breast cancer and to identify imaging markers that influences the prognosis and treatment according to subtypes.

METHODS

From June 2017 to August 2018, MRIs of 95 women with invasive breast cancer were prospectively analyzed, using the breast imaging-reporting and data system and texture analysis. Whole RNA obtained from surgical specimens was analyzed using next-generation sequencing. The association between MRI features and gene expression profiles was analyzed in the entire tumor and subtypes. Gene networks, enriched functions, and canonical pathways were analyzed using Ingenuity Pathway Analysis. The P value for differential expression was obtained using a parametric F test comparing nested linear models and adjusted for multiple testing by reporting Q value.

RESULTS

In 95 participants (mean age, 53 years ± 11 [standard deviation]), mass lesion type was associated with upregulation of CCL3L1 (sevenfold) and irregular mass shape was associated with downregulation of MIR421 (sixfold). In estrogen receptor-positive cancer with mass lesion type, CCL3L1 (21-fold), SNHG12 (11-fold), and MIR206 (sevenfold) were upregulated, and MIR597 (265-fold), MIR126 (12-fold), and SOX17 (fivefold) were downregulated. In triple-negative breast cancer with increased standard deviation of texture analysis on precontrast T1-weighted imaging, CLEC3A (23-fold), SRGN (13-fold), HSPG2 (sevenfold), KMT2D (fivefold), and VMP1 (fivefold) were upregulated, and IGLC2 (73-fold) and PRDX4 (sevenfold) were downregulated (all, P < 0.05 and Q < 0.1). Gene network and functional analysis showed that mass type estrogen receptor-positive cancers were associated with cell growth, anti-estrogen resistance, and poor survival.

CONCLUSION

MRI characteristics are associated with the different expressions of genes related to metastasis, anti-drug resistance, and prognosis, depending on the molecular subtypes of breast cancer.

The Role of Thrombomodulin in Estrogen-Receptor-Positive Breast Cancer Progression, Metastasis, and Curcumin Sensitivity

Estrogen and estrogen receptors (ER) play a key role in breast cancer progression, which can be treated with endocrine therapy. Nevertheless, resistance to endocrine therapies is developed over time. The tumor expression of thrombomodulin (TM) is correlated with favorable prognosis in several types of cancer. However, this correlation has not yet been confirmed in ER-positive (ER⁺) breast cancer. This study aims to evaluate the role of TM in ER⁺ breast cancer. Firstly, we found that lower TM expression correlates to poor overall survival (OS) and relapse-free survival (RFS) rates in ER⁺ breast cancer patients through Kaplan-Meier survival analysis (p < 0.05). Silencing TM in MCF7 cells (TM-KD) increased cell proliferation, migration, and invasion ability. Additionally, TM-KD MCF7 cells showed higher sensitivity (IC₅₀ 15 μM) to the anti-cancer agent curcumin than the scrambled control cells. Conversely, overexpression of TM (TM-over) in T47D cells leads to decreased cell proliferation, migration, and invasion ability. Furthermore, TM-over T47D cells showed more resistance (IC₅₀ > 40 μM) to the curcumin treatment. The PI staining, DAPI, and tunnel assay also confirmed that the curcumin-induced apoptosis in TM-KD MCF7 cells was higher (90.34%) than in the scrambled control cells (48.54%). Finally, the expressions of drug-resistant genes (ABCC1, LRP1, MRP5, and MDR1) were determined by qPCR. We found that the relative mRNA expression levels of ABCC1, LRP1, and MDR1 genes after curcumin treatment were higher in scrambled control cells than in TM-KD cells. In conclusion, our results demonstrated that TM plays a suppressive role in the progression and metastasis of ER⁺ breast cancer, and it regulates curcumin sensitivity by interfering with ABCC1, LRP1, and MDR1 gene expression.

Adaptive and non-adaptive gene expression responses in prostate cancer during androgen deprivation

Androgen deprivation therapy is the cornerstone treatment of advanced prostate cancer. Eventually prostate cancer cells overcome androgen deprivation therapy, giving rise to castration resistant prostate cancer (CRPC) characterized by increased androgen receptor (AR) activity. Understanding the cellular mechanisms leading to CRPC is needed for development of novel treatments. We used long-term cell cultures to model CRPC; a testosterone-dependent cell line (VCaP-T) and cell line adapted to grow in low testosterone (VCaP-CT). These were used to uncover persistent and adaptive responses to testosterone level. RNA was sequenced to study AR-regulated genes. Expression level changed due to testosterone depletion in 418 genes in VCaP-T (AR-associated genes). To evaluate significance for CRPC growth, we compared which of them were adaptive i.e., restored expression level in VCaP-CT. Adaptive genes were enriched to steroid metabolism, immune response and lipid metabolism. The Cancer Genome Atlas Prostate Adenocarcinoma data were used to assess the association with cancer aggressiveness and progression-free survival. Expressions of 47 AR-associated or association gaining genes were statistically significant markers for progression-free survival. These included genes related to immune response, adhesion and transport. Taken together, we identified and clinically validated multiple genes being linked with progression of prostate cancer and propose several novel risk genes. Possible use as biomarkers or therapeutic targets should be studied further.

Circular Sponge against miR-21 Enhances the Antitumor Activity of Doxorubicin against Breast Cancer Cells

Breast cancer is the most common type of cancer in women, with chemotherapy being the main strategy. However, its effectiveness is reduced by drug resistance mechanisms. miR-21 is upregulated in breast cancer that has been linked to drug resistance and carcinogenic processes. Our aim was to capture miR-21 with a circular sponge (Circ-21) and thus inhibit the carcinogenic processes and drug resistance mechanisms in which it participates. Proliferation, migration, colony formation, cell cycle, and poly [ADP-ribose] polymerase 1 (PARP-1) and vascular endothelial growth factor (VEGF) detection assays were performed with MCF7 breast cancer cells and MCF10A non-tumor cells. In addition, doxorubicin resistance tests and detection of drug resistance gene expression were performed in MCF7 cells. Reduction in proliferation, as well as migration and colony formation, increased PARP-1 expression, inhibition of VEGF expression and cell cycle arrest in G2/M phase were displayed in the Circ-21 MCF7, which were not observed in the MCF10A cells. Furthermore, in the MCF7 cells, the Circ-21 enhanced the antitumor activity of doxorubicin and decreased the expression of resistance genes: ABCA1, ABCC4, and ABCC5. Based on these results, the use of Circ-21 can be considered a first step for the establishment of an effective gene therapy in the treatment of breast cancer.

Variational Bayes for high-dimensional proportional hazards models with applications within gene expression

MOTIVATION

Few Bayesian methods for analyzing high-dimensional sparse survival data provide scalable variable selection, effect estimation and uncertainty quantification. Such methods often either sacrifice uncertainty quantification by computing maximum a posteriori estimates, or quantify the uncertainty at high (unscalable) computational expense.

RESULTS

We bridge this gap and develop an interpretable and scalable Bayesian proportional hazards model for prediction and variable selection, referred to as sparse variational Bayes. Our method, based on a mean-field variational approximation, overcomes the high computational cost of Markov chain Monte Carlo, whilst retaining useful features, providing a posterior distribution for the parameters and offering a natural mechanism for variable selection via posterior inclusion probabilities. The performance of our proposed method is assessed via extensive simulations and compared against other state-of-the-art Bayesian variable selection methods, demonstrating comparable or better performance. Finally, we demonstrate how the proposed method can be used for variable selection on two transcriptomic datasets with censored survival outcomes, and how the uncertainty quantification offered by our method can be used to provide an interpretable assessment of patient risk.

AVAILABILITY AND IMPLEMENTATION

our method has been implemented as a freely available R package survival.svb (https://github.com/mkomod/survival.svb).

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Non-drug efflux function of ABCC5 promotes enzalutamide resistance in castration-resistant prostate cancer via upregulation of P65/AR-V7

Drug resistance is responsible for castration-resistant prostate cancer (CRPC)-associated mortality. While ATP binding cassette subfamily C member 5 (ABCC5) has been reported to regulate multiple drug resistance, its drug-efflux function may not be the main reason underlying resistance to enzalutamide, an androgen receptor inhibitor. Here, we aimed to determine whether the non-drug efflux function of ABCC5 affects enzalutamide resistance. The ABCC5 expression data in patients with prostate cancer (PCa) were retrieved from The Cancer Genome Atlas and Gene Expression Omnibus, and their correlation with disease prognosis was analyzed. Immunohistochemical staining was performed on a cohort of 80 patient samples. Proliferation of enzalutamide-resistant 22RV1 and C4-2B cells was investigated using CCK-8, EdU, and colony formation assays. The effect of ABCC5 silencing on enzalutamide resensitization was evaluated in vitro and in vivo. Functional assays indicated that ABCC5 depletion resensitized enzalutamide-resistant cells to inhibit cell growth and impeded xenograft tumor proliferation. Mechanistically, luciferase and ChIP assays confirmed that P65 regulated AR expression and activity by binding to its promoter, while ABCC5-mediated resistance effected by AR-V7 (one of the widely studied AR splicing variants that meditate AR antagonist resistance) upregulation could be reversed by P65 knockdown. Furthermore, activation of the NF-κB pathway reversed the effects of ABCC5 knockdown by extra AR-V7 expression. Thus, ABCC5 might be a novel target for enzalutamide-resistant CRPC treatment.

Adenosine triphosphate-binding cassette subfamily C members in liver hepatocellular carcinoma: Bioinformatics-driven prognostic value

Aberrant expression of adenosine triphosphate-binding cassette subfamily C (ABCC), one of the largest superfamilies and transporter gene families of membrane proteins, is associated with various tumors. However, its relationship with liver hepatocellular carcinoma (LIHC) remains unclear.We used the Oncomine, UALCAN, Human Protein Atlas, GeneMANIA, GO, Kyoto Encyclopedia of Genes and Genomes (KEGG), TIMER, and Kaplan-Meier Plotter databases. On May 20, 2021, we searched these databases for the terms ABCC1, ABCC2, ABCC3, ABCC4, ABCC5, ABCC6, ABCC7, ABCC8, ABCC9, ABCC10, ABCC11, ABCC12, ABCC13, and "liver cancer." The exposure group comprised LIHC patients, and the control group comprised normal patients (those with noncancerous liver tissue). All patients shown in the retrieval language search were included. We compared the mRNA expression of these proteins in LIHC and control patients to examine the potential role of ABCC1-13 in LIHC.Relative to the normal liver tissue, mRNA expression of ABCC1/2/3/4/5/6/10 was significantly upregulated (P < .001), and that of ABCC9/11 significantly downregulated (both P < .001), in LIHC. ABCC mRNA expression varied with gender (P < .05), except for ABCC11-13; with tumor grade (P < 0.05), except for ABCC7/12/13; with tumor stage (P < .05), except for ABCC11-13; and with lymph node metastasis status (P < .05), except for ABCC7/8/11/12/13. Based on KEGG enrichment analysis, these genes were associated with the following pathways: ABC transporters, Bile secretion, Antifolate resistance, and Peroxisome (P < .05). Except for ABCC12/13, the ABCCs were significantly associated with B cell, CD8+ T cell, CD4+ T cell, macrophage, neutrophil, and dendritic cell infiltration (P < .05). High mRNA expression of ABCC1/4/5/8 (P < .05) and low expression of ABCC6/7/9/12/13 (P < .05) indicated poor prognosis. Prognostic significance was indicated for ABCC2/13 for both men and women (P < .05); for ABCC1/6/12/13 for tumor grades 1-3 (P < .05); for ABCC5/11/12/13 for all tumor stages (P < .05); for ABCC1/11/12/13 for American Joint Committee on Cancer T stages 1-3 (P < .05); and for ABCC1/5/6/13 for vascular invasion. None showed prognostic significance for microvascular invasion (P < .05).We identified ABCC1/2/3/4/5/6/9/10/11 as potential diagnostic markers, and ABCC1/4/5/6/7/8/9/12/13 as prognostic markers, of LIHC. Our future work will promote the use of ABCCs in the diagnosis and treatment of LIHC.

A Unified Transcriptional, Pharmacogenomic, and Gene Dependency Approach to Decipher the Biology, Diagnostic Markers, and Therapeutic Targets Associated with Prostate Cancer Metastasis

Simple Summary

This manuscript demonstrates how integrated bioinformatic and statistical reanalysis of publicly available genomic datasets can be utilized to identify molecular pathways and biomarkers that may be clinically relevant to metastatic prostate cancer (mPrCa) progression. The most notable observation is that the transition from primary prostate cancer to mPrCa is characterized by upregulation of processes associated with DNA replication, metastasis, and events regulated by the serine/threonine kinase PLK1. Moreover, our analysis also identified over-expressed genes that may be exploited for potential targeted therapeutics and minimally invasive diagnostics and monitoring of mPrCa. The primary data analyzed were two transcriptional datasets for tissues derived from normal prostate, primary prostate cancer, and mPrCa. Also incorporated in the analysis were the transcriptional, gene dependency, and drug response data for hundreds of cell lines, including those derived from prostate cancer tissues.

Abstract

Our understanding of metastatic prostate cancer (mPrCa) has dramatically advanced during the genomics era. Nonetheless, many aspects of the disease may still be uncovered through reanalysis of public datasets. We integrated the expression datasets for 209 PrCa tissues (metastasis, primary, normal) with expression, gene dependency (GD) (from CRISPR/cas9 screen), and drug viability data for hundreds of cancer lines (including PrCa). Comparative statistical and pathways analyses and functional annotations (available inhibitors, protein localization) revealed relevant pathways and potential (and previously reported) protein markers for minimally invasive mPrCa diagnostics. The transition from localized to mPrCa involved the upregulation of DNA replication, mitosis, and PLK1-mediated events. Genes highly upregulated in mPrCa and with very high average GD (~1) are potential therapeutic targets. We showed that fostamatinib (which can target PLK1 and other over-expressed serine/threonine kinases such as AURKA, MELK, NEK2, and TTK) is more active against cancer lines with more pronounced signatures of invasion (e.g., extracellular matrix organization/degradation). Furthermore, we identified surface-bound (e.g., ADAM15, CD276, ABCC5, CD36, NRP1, SCARB1) and likely secreted proteins (e.g., APLN, ANGPT2, CTHRC1, ADAM12) that are potential mPrCa diagnostic markers. Overall, we demonstrated that comprehensive analyses of public genomics data could reveal potentially clinically relevant information regarding mPrCa.

MAPK1/3 kinase-dependent ULK1 degradation attenuates mitophagy and promotes breast cancer bone metastasis

The function of mitophagy in cancer is controversial. ULK1 is critical for induction of macroautophagy/autophagy and has a more specific role in mitophagy in response to hypoxia. Here, we show that ULK1 deficiency induces an invasive phenotype of breast cancer cells under hypoxia and increases osteolytic bone metastasis. Mechanistically, ULK1 depletion attenuates mitophagy ability during hypoxia. As a result, the accumulation of damaged, ROS-generating mitochondria leads to activation of the NLRP3 inflammasome, which induces abnormal soluble cytokines secretion, then promotes the differentiation and maturation of osteoclasts, and ultimately results in bone metastasis. Notably, phosphorylation of ULK1 by MAPK1/ERK2-MAPK3/ERK1 kinase triggers its interaction with BTRC and subsequent K48-linked ubiquitination and proteasome degradation. Also, a clearly negative correlation between the expression levels of ULK1 and p-MAPK1/3 was observed in human breast cancer tissues. The MAP2K/MEK inhibitor trametinib is sufficient to restore mitophagy function via upregulation of ULK1, leading to inhibition of NLRP3 inflammasome activation, thereby reduces bone metastasis. These results indicate that ULK1 knockout-mediated mitophagy defect promotes breast cancer bone metastasis and provide evidence to explore MAP2K/MEK- MAPK1/3 pathway inhibitors for therapy, especially in cancers displaying low levels of ULK1.Abbreviations: ATG: autophagy-related; Baf A1: bafilomycin A₁; BTRC/β-TrCP: beta-transducin repeat containing E3 ubiquitin protein ligase; CHX: cycloheximide; CM: conditioned media; FBXW7/FBW7: F-box and WD repeat domain containing 7; MAPK1: mitogen-activated protein kinase 1; MTDR: MitoTracker Deep Red; mtROS: mitochondrial reactive oxygen species; microCT: micro-computed tomography; mtROS: mitochondrial reactive oxygen species; OCR: oxygen consumption rate; SQSTM1: sequestosome 1; ACP5/TRAP: acid phosphatase, tartrate resistant; ULK1: unc-51 like autophagy activating kinase 1.

Identification and Validation of Esophageal Squamous Cell Carcinoma Targets for Fluorescence Molecular Endoscopy

Dysplasia and intramucosal esophageal squamous cell carcinoma (ESCC) frequently go unnoticed with white-light endoscopy and, therefore, progress to invasive tumors. If suitable targets are available, fluorescence molecular endoscopy might be promising to improve early detection. Microarray expression data of patient-derived normal esophagus (n = 120) and ESCC samples (n = 118) were analyzed by functional genomic mRNA (FGmRNA) profiling to predict target upregulation on protein levels. The predicted top 60 upregulated genes were prioritized based on literature and immunohistochemistry (IHC) validation to select the most promising targets for fluorescent imaging. By IHC, GLUT1 showed significantly higher expression in ESCC tissue (30 patients) compared to the normal esophagus adjacent to the tumor (27 patients) (p < 0.001). Ex vivo imaging of GLUT1 with the 2-DG 800CW tracer showed that the mean fluorescence intensity in ESCC (n = 17) and high-grade dysplasia (HGD, n = 13) is higher (p < 0.05) compared to that in low-grade dysplasia (LGD) (n = 7) and to the normal esophagus adjacent to the tumor (n = 5). The sensitivity and specificity of 2-DG 800CW to detect HGD and ESCC is 80% and 83%, respectively (ROC = 0.85). We identified and validated GLUT1 as a promising molecular imaging target and demonstrated that fluorescent imaging after topical application of 2-DG 800CW can differentiate HGD and ESCC from LGD and normal esophagus.

A Role for TGFβ Signaling in Preclinical Osteolytic Estrogen Receptor-Positive Breast Cancer Bone Metastases Progression

While tumoral Smad-mediated transforming growth factor β (TGFβ) signaling drives osteolytic estrogen receptor α-negative (ER-) breast cancer bone metastases (BMETs) in preclinical models, its role in ER+ BMETs, representing the majority of clinical BMETs, has not been documented. Experiments were undertaken to examine Smad-mediated TGFβ signaling in human ER+ cells and bone-tropic behavior following intracardiac inoculation of estrogen (E2)-supplemented female nude mice. While all ER+ tumor cells tested (ZR-75-1, T47D, and MCF-7-derived) expressed TGFβ receptors II and I, only cells with TGFβ-inducible Smad signaling (MCF-7) formed osteolytic BMETs in vivo. Regulated secretion of PTHrP, an osteolytic factor expressed in >90% of clinical BMETs, also tracked with osteolytic potential; TGFβ and E2 each induced PTHrP in bone-tropic or BMET-derived MCF-7 cells, with the combination yielding additive effects, while in cells not forming BMETs, PTHrP was not induced. In vivo treatment with 1D11, a pan-TGFβ neutralizing antibody, significantly decreased osteolytic ER+ BMETs in association with a decrease in bone-resorbing osteoclasts at the tumor-bone interface. Thus, TGFβ may also be a driver of ER+ BMET osteolysis. Moreover, additive pro-osteolytic effects of tumoral E2 and TGFβ signaling could at least partially explain the greater propensity for ER+ tumors to form BMETs, which are primarily osteolytic.

Varied clinical significance of ATP-binding cassette C sub-family members for lung adenocarcinoma

Lung adenocarcinoma (LUAD) is a lethal malignancy worldwide and a major public health concern. We explored the potential clinical significance for LUAD of ATP-binding cassette (ABC), sub-family C, consisting of ABCC1-6, 8-12, and cystic fibrosis transmembrane conductance regulator (CFTR).Five hundred LUAD patients from The Cancer Genome Atlas database were used for analysis, including differential expression and diagnostic and prognostic significance. Oncomine and MERAV databases were used to validate differential expression and diagnostic significance. A risk score model was constructed using prognosis-related ABCC members. Prognosis-related genes were further explored to correlate their expression with tumor stage progression. Interaction networks, including biological processes and metabolic pathways, were constructed using Cytoscape software and STRING website.ABCC1-3 consistently showed high expression in tumor tissues (all P ≤ 0.05). Most datasets indicated that ABCC5, 10, and 11 were highly expressed in tumor tissues whereas ABCC6, 9, and CFTR were highly expressed in nontumor tissues (all P ≤ 0.05). Diagnostic significance of ABCC3 and ABCC5 was consistently assessed and validated in three datasets (all area under the curve > 0.700) whereas ABCC6, 8, 10, 11, and CFTR were assessed in The Cancer Genome Atlas dataset and validated in one dataset (all area under the curve > 0.700). Prognostic analysis indicated that ABCC2, 6, and 8 mRNA expression was associated with survival of LUAD (all adjusted P ≤ .037). The risk score model constructed using ABCC2, 6, and 8 suggested prognostic significance for survival predictions. ABCC2 expression was associated with tumor stage, whereas ABCC6 and 8 were not. Interaction networks indicated that they were involved in establishment of localization, ion transport, plasma membrane, apical plasma membrane, adenylyl nucleotide binding, ABC transporters, ABC transporter disorders, ABC-family-protein-mediated transport, and bile secretion.Differentially expressed ABCC2 and ABCC5 might be diagnostic whereas ABCC2, 6, and 8 may be prognostic biomarkers for LUAD, possibly through ABC-family-mediated transporter disorders.

Pleiotropic Roles of ABC Transporters in Breast Cancer

Chemotherapeutics are the mainstay treatment for metastatic breast cancers. However, the chemotherapeutic failure caused by multidrug resistance (MDR) remains a pivotal obstacle to effective chemotherapies of breast cancer. Although in vitro evidence suggests that the overexpression of ATP-Binding Cassette (ABC) transporters confers resistance to cytotoxic and molecularly targeted chemotherapies by reducing the intracellular accumulation of active moieties, the clinical trials that target ABCB1 to reverse drug resistance have been disappointing. Nevertheless, studies indicate that ABC transporters may contribute to breast cancer development and metastasis independent of their efflux function. A broader and more clarified understanding of the functions and roles of ABC transporters in breast cancer biology will potentially contribute to stratifying patients for precision regimens and promote the development of novel therapies. Herein, we summarise the current knowledge relating to the mechanisms, functions and regulations of ABC transporters, with a focus on the roles of ABC transporters in breast cancer chemoresistance, progression and metastasis.

MAPK1/3 kinase-dependent ULK1 degradation attenuates mitophagy and promotes breast cancer bone metastasis

The function of mitophagy in cancer is controversial. ULK1 is critical for induction of macroautophagy/autophagy and has a more specific role in mitophagy in response to hypoxia. Here, we show that ULK1 deficiency induces an invasive phenotype of breast cancer cells under hypoxia and increases osteolytic bone metastasis. Mechanistically, ULK1 depletion attenuates mitophagy ability during hypoxia. As a result, the accumulation of damaged, ROS-generating mitochondria leads to activation of the NLRP3 inflammasome, which induces abnormal soluble cytokines secretion, then promotes the differentiation and maturation of osteoclasts, and ultimately results in bone metastasis. Notably, phosphorylation of ULK1 by MAPK1/ERK2-MAPK3/ERK1 kinase triggers its interaction with BTRC and subsequent K48-linked ubiquitination and proteasome degradation. Also, a clearly negative correlation between the expression levels of ULK1 and p-MAPK1/3 was observed in human breast cancer tissues. The MAP2K/MEK inhibitor trametinib is sufficient to restore mitophagy function via upregulation of ULK1, leading to inhibition of NLRP3 inflammasome activation, thereby reduces bone metastasis. These results indicate that ULK1 knockout-mediated mitophagy defect promotes breast cancer bone metastasis and provide evidence to explore MAP2K/MEK- MAPK1/3 pathway inhibitors for therapy, especially in cancers displaying low levels of ULK1.Abbreviations: ATG: autophagy-related; Baf A1: bafilomycin A₁; BTRC/β-TrCP: beta-transducin repeat containing E3 ubiquitin protein ligase; CHX: cycloheximide; CM: conditioned media; FBXW7/FBW7: F-box and WD repeat domain containing 7; MAPK1: mitogen-activated protein kinase 1; MTDR: MitoTracker Deep Red; mtROS: mitochondrial reactive oxygen species; microCT: micro-computed tomography; mtROS: mitochondrial reactive oxygen species; OCR: oxygen consumption rate; SQSTM1: sequestosome 1; ACP5/TRAP: acid phosphatase, tartrate resistant; ULK1: unc-51 like autophagy activating kinase 1.

Breast cancer prognosis signature: linking risk stratification to disease subtypes

Breast cancer is a very complex and heterogeneous disease with variable molecular mechanisms of carcinogenesis and clinical behaviors. The identification of prognostic risk factors may enable effective diagnosis and treatment of breast cancer. In particular, numerous gene-expression-based prognostic signatures were developed and some of them have already been applied into clinical trials and practice. In this study, we summarized several representative gene-expression-based signatures with significant prognostic value and separately assessed their ability of prognosis prediction in their originally targeted populations of breast cancer. Notably, many of the collected signatures were originally designed to predict the outcomes of estrogen receptor positive (ER+) patients or the whole breast cancer cohort; there are no typical signatures used for the prognostic prediction in a specific population of patients with the intrinsic subtype. We thus attempted to identify subtype-specific prognostic signatures via a computational framework for analyzing multi-omics profiles and patient survival. For both the discovery and an independent data set, we confirmed that subtype-specific signature is a strong and significant independent prognostic factor in the corresponding cohort. These results indicate that the subtype-specific prognostic signature has a much higher resolution in the risk stratification, which may lead to improved therapies and precision medicine for patients with breast cancer.

Prognostic role of alternative splicing events in head and neck squamous cell carcinoma

Background

Aberrant alternative splicing (AS) is implicated in biological processes of cancer. This study aims to reveal prognostic AS events and signatures that may serve as prognostic predictors for head and neck squamous cell carcinoma (HNSCC).

Methods

Prognostic AS events in HNSCC were identified by univariate COX analysis. Prognostic signatures comprising prognostic AS events were constructed for prognosis prediction in patients with HNSCC. The correlation between the percent spliced in (PSI) values of AS events and the expression of splicing factors (SFs) was analyzed by Pearson correlation analysis. Gene functional annotation analysis was performed to reveal pathways in which prognostic AS is enriched.

Results

A total of 27,611 AS events in 15,873 genes were observed, and there were 3433 AS events in 2624 genes significantly associated with overall survival (OS) for HNSCC. Moreover, we found that AS prognostic signatures could accurately predict HNSCC prognosis. SF-AS regulatory networks were constructed according to the correlation between PSI values of AS events and the expression levels of SFs.

Conclusions

Our study identified prognostic AS events and signatures. Furthermore, it established SF-AS networks in HNSCC that were valuable in predicting the prognosis of patients with HNSCC and elucidating the regulatory mechanisms underlying AS in HNSCC.

Extracellular Vesicle microRNAs Contribute to the Osteogenic Inhibition of Mesenchymal Stem Cells in Multiple Myeloma

Osteolytic bone disease is the major complication associated with the progression of multiple myeloma (MM). Recently, extracellular vesicles (EVs) have emerged as mediators of MM-associated bone disease by inhibiting the osteogenic differentiation of human mesenchymal stem cells (hMSCs). Here, we investigated a correlation between the EV-mediated osteogenic inhibition and MM vesicle content, focusing on miRNAs. By the use of a MicroRNA Card, we identified a pool of miRNAs, highly expressed in EVs, from MM cell line (MM1.S EVs), expression of which was confirmed in EVs from bone marrow (BM) plasma of patients affected by smoldering myeloma (SMM) and MM. Notably, we found that miR-129-5p, which targets different osteoblast (OBs) differentiation markers, is enriched in MM-EVs compared to SMM-EVs, thus suggesting a selective packaging correlated with pathological grade. We found that miR-129-5p can be transported to hMSCs by MM-EVs and, by the use of miRNA mimics, we investigated its role in recipient cells. Our data demonstrated that the increase of miR-129-5p levels in hMSCs under osteoblastic differentiation stimuli inhibited the expression of the transcription factor Sp1, previously described as a positive modulator of osteoblastic differentiation, and of its target the Alkaline phosphatase (ALPL), thus identifying miR-129-5p among the players of vesicle-mediated bone disease.

Causal Inference Network of Genes Related with Bone Metastasis of Breast Cancer and Osteoblasts Using Causal Bayesian Networks

Background

The causal networks among genes that are commonly expressed in osteoblasts and during bone metastasis (BM) of breast cancer (BC) are not well understood. Here, we developed a machine learning method to obtain a plausible causal network of genes that are commonly expressed during BM and in osteoblasts in BC.

Methods

We selected BC genes that are commonly expressed during BM and in osteoblasts from the Gene Expression Omnibus database. Bayesian Network Inference with Java Objects (Banjo) was used to obtain the Bayesian network. Genes registered as BC related genes were included as candidate genes in the implementation of Banjo. Next, we obtained the Bayesian structure and assessed the prediction rate for BM, conditional independence among nodes, and causality among nodes. Furthermore, we reported the maximum relative risks (RRs) of combined gene expression of the genes in the model.

Results

We mechanistically identified 33 significantly related and plausibly involved genes in the development of BC BM. Further model evaluations showed that 16 genes were enough for a model to be statistically significant in terms of maximum likelihood of the causal Bayesian networks (CBNs) and for correct prediction of BM of BC. Maximum RRs of combined gene expression patterns showed that the expression levels of UBIAD1, HEBP1, BTNL8, TSPO, PSAT1, and ZFP36L2 significantly affected development of BM from BC.

Conclusions

The CBN structure can be used as a reasonable inference network for accurately predicting BM in BC.

Transcriptomic and functional network features of lung squamous cell carcinoma through integrative analysis of GEO and TCGA data

Lung squamous cell carcinoma (LUSC) is associated with poor clinical prognosis and lacks available targeted therapy. Novel molecules are urgently required for the diagnosis and prognosis of LUSC. Here, we conducted our data mining analysis for LUSC by integrating the differentially expressed genes acquired from Gene Expression Omnibus (GEO) database by comparing tumor tissues versus normal tissues (GSE8569, GSE21933, GSE33479, GSE33532, GSE40275, GSE62113, GSE74706) into The Cancer Genome Atlas (TCGA) database which includes 502 tumors and 49 adjacent non-tumor lung tissues. We identified intersections of 129 genes (91 up-regulated and 38 down-regulated) between GEO data and TCGA data. Based on these genes, we conducted our downstream analysis including functional enrichment analysis, protein-protein interaction, competing endogenous RNA (ceRNA) network and survival analysis. This study may provide more insight into the transcriptomic and functional features of LUSC through integrative analysis of GEO and TCGA data and suggests therapeutic targets and biomarkers for LUSC.

Data integration by multi-tuning parameter elastic net regression

Background

To integrate molecular features from multiple high-throughput platforms in prediction, a regression model that penalizes features from all platforms equally is commonly used. However, data from different platforms are likely to differ in effect sizes, the proportion of predictive features, and correlations structures. Subtle but important features may be missed by shrinking all features equally.

Results

We propose an Elastic net (EN) model with separate tuning parameter penalties for each platform that is fit using standard software. In a comprehensive simulation study, we evaluated the performance of EN logistic regression with multiple tuning penalties. We found that when the number of informative features differs among the platforms, and when there is no notable correlation between the features from different platforms, the multi-tuning parameter EN yields more predictive models. Moreover, the multi-tuning parameter EN is robust, in the sense that there is no loss of predictivity relative to a single tuning parameter EN when features across all platforms have similar effects. We also investigated the performance of multi-tuning parameter EN using real cancer datasets.

Conclusion

The proposed multi-tuning parameter EN model, fit using standard penalized regression software, can achieve better prediction in sample classification when integrating multiple genomic platforms, compared to the traditional method where a single penalty parameter is used for all features in different platforms.

Electronic supplementary material

The online version of this article (10.1186/s12859-018-2401-1) contains supplementary material, which is available to authorized users.

Maternal western-style diet enhances the effects of chemically-induced mammary tumors in female rat offspring through transcriptome changes

Previous studies have shown that early life intake of high-fat diet or western-style diet (WD) enhances the development of mammary tumors in adult female rats. Thus, we hypothesized that maternal WD throughout pregnancy and the lactation period could speed up the development of MNU-induced mammary tumors and alter their gene expression. For this, the present study investigated the gene expression profile of chemically-induced mammary tumors in female rat offspring from dams fed a WD or a control diet. Pregnant female Sprague-Dawley rats received a WD (high-fat, low-fiber and oligoelements) or a control diet from gestational day 12 until post-natal day (PND) 21. At PND 21, female offspring received a single dose of N-Methyl-N-Nitrosourea (MNU, 50 mg/kg body weight) and were fed a control diet for 13 weeks. Tumor incidence, multiplicity, and latency were recorded and mammary gland samples were collected for histopathology and gene expression analysis. Tumor multiplicity and histological grade were significantly higher and tumor latency was lower in WD offspring compared to control offspring. Transcriptome profiling identified 57 differentially expressed genes in tumors from WD offspring as compared to control offspring. There was also an increase in mRNA expression of genes such as Emp3, Ccl7, Ets1, Abcc5, and Cyr61, indicative of more aggressive disease detected in tumors from WD offspring. Thus, maternal WD diet increased MNU-induced mammary carcinogenesis in adult female offspring through transcriptome changes that resulted in a more aggressive disease.

Loss of miR-516a-3p mediates upregulation of ABCC5 in prostate cancer and drives its progression

To gain a comprehensive understanding of whether ABCC5 can regulate prostate cancer (PCa) progression, we performed microarray data analyses and identified that ABCC5 was drastically increased in primary PCa relative to normal samples, metastatic PCa relative to primary PCa, and castration-resistant PCa relative to hormone naïve PCa, respectively. Multivariate Cox regression analysis suggested that ABCC5 overexpression in PCa was an independent prognostic factor for both poor biochemical recurrence-free and overall survival. We demonstrated that ABCC5 knockdown significantly inhibits PCa cell proliferation, migration, and invasion in vitro and suppresses tumor growth and metastasis in vivo. We also demonstrated that miR-516a-3p was significantly downregulated in PCa. We finally demonstrated that ABCC5 was a direct target of miR-516a-3p. miR-516a-3p overexpression can phenotypically copy ABCC5 knockdown-induced phenotypes, whereas forced expression of ABCC5 can drastically reverse the inhibitory effects of miR-516a-3p. miR-516a-3p may modulate the sensitivity of cancer cells to adriamycin and docetaxel by targeting ABCC5 with important implications in the design of new therapeutic agents. Taken together, our results indicated that loss of miR-516a-3p expression and thus uncontrolled ABCC5 upregulation might drive PCa progression and influence chemosensitivity.

Development of liposomal pemetrexed for enhanced therapy against multidrug resistance mediated by ABCC5 in breast cancer

Purpose

Breast cancer is the most common cancer among women. Pemetrexed, a new generation antifolate drug, is one of the primary treatments for breast cancer. However, multidrug resistance (MDR) in breast cancer greatly hampers the therapeutic efficacy of chemotherapies such as pemetrexed. Nanomedicine is emerging as a promising alternative technique to overcome cancer MDR. Thus, pemetrexed-loaded d-alpha tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS) liposomes (liposomal pemetrexed) were developed as a strategy to overcome MDR to pemetrexed in breast cancer.

Materials and methods

Liposomal pemetrexed was developed using the calcium acetate gradient method. The cytotoxic effects, apoptosis-inducing activity, in vivo distribution, and antitumor activity of liposomal pemetrexed were investigated.

Results

Liposomal pemetrexed was small in size (160.77 nm), with a small polydispersity of <0.1. The encapsulation efficacy of liposomal pemetrexed was 63.5%, which is rather high for water-soluble drugs in liposomes. The IC₅₀ of liposomal pemetrexed following treatment with MDR breast cancer cells (MCF-7 cells overexpressing ABCC5) was 2.6-fold more effective than pemetrexed. The in vivo biodistribution study showed that the liposomes significantly accumulated in tumors 24 h after injection. The antitumor assay in mice bearing MDR breast cancer xenograft tumors confirmed the superior antitumor activity of liposomal pemetrexed over pemetrexed. It was also found that the improved therapeutic effect of liposomal pemetrexed may be attributed to apoptosis through both extrinsic and intrinsic pathways.

Conclusion

Liposomal pemetrexed represents a potential therapeutic approach for overcoming breast cancer MDR.

Nitric Oxide Synthase-2-Derived Nitric Oxide Drives Multiple Pathways of Breast Cancer Progression

SIGNIFICANCE

Breast cancer is the second leading cause of cancer-related deaths among women in the United States. Development and progression of malignancy are associated with diverse cell signaling pathways that control cell proliferation, survival, motility, invasion, and metastasis. Recent Advances: An increasing number of clinical studies have implicated a strong relationship between elevated tumor nitric oxide synthase-2 (NOS2) expression and poor patient survival.

CRITICAL ISSUES

Herein, we review what we believe to be key mechanisms in the role(s) of NOS2-derived nitric oxide (NO) as a driver of breast cancer disease progression. High NO increases cyclooxygenase-2 activity, hypoxia inducible factor-1 alpha protein stabilization, and activation of important cell signaling pathways, including phosphoinositide 3-kinase/protein kinase B, mitogen-activated protein kinase, epidermal growth factor receptor, and Ras, through post-translational protein modifications. Moreover, dysregulated NO flux within the tumor microenvironment has other important roles, including the promotion of angiogenesis and modulation of matrix metalloproteinase/tissue inhibitor matrix metalloproteinase associated with tumor progression.

FUTURE DIRECTIONS

The elucidation of these and other NO-driven pathways implicates NOS2 as a key driver of breast cancer disease progression and provides a new perspective in the identification of novel targets that may be therapeutically beneficial in the treatment of estrogen receptor-negative disease. Antioxid. Redox Signal. 26, 1044-1058.

5'-Inositol phosphatase SHIP2 recruits Mena to stabilize invadopodia for cancer cell invasion

Invadopodia are membrane protrusions used by cancer cells to remodel and invade the extracellular matrix. Here, Rajadurai et al. show that the lipid phosphatase SHIP2 recruits the Ena/VASP-family actin regulatory protein Mena to stabilize invadopodia membrane protrusions and promote cell invasion.

Invadopodia are specialized membrane protrusions that support degradation of extracellular matrix (ECM) by cancer cells, allowing invasion and metastatic spread. Although early stages of invadopodia assembly have been elucidated, little is known about maturation of invadopodia into structures competent for ECM proteolysis. The localized conversion of phosphatidylinositol(3,4,5)-triphosphate and accumulation of phosphatidylinositol(3,4)-bisphosphate at invadopodia is a key determinant for invadopodia maturation. Here we investigate the role of the 5′-inositol phosphatase, SHIP2, and reveal an unexpected scaffold function of SHIP2 as a prerequisite for invadopodia-mediated ECM degradation. Through biochemical and structure-function analyses, we identify specific interactions between SHIP2 and Mena, an Ena/VASP-family actin regulatory protein. We demonstrate that SHIP2 recruits Mena, but not VASP, to invadopodia and that disruption of SHIP2–Mena interaction in cancer cells leads to attenuated capacity for ECM degradation and invasion in vitro, as well as reduced metastasis in vivo. Together, these findings identify SHIP2 as a key modulator of carcinoma invasiveness and a target for metastatic disease.

Unleashing Cancer Cells on Surfaces Exposing Motogenic IGDQ Peptides

Thiolated peptides bearing the Ile-Gly-Asp (IGD) motif, a highly conserved sequence of fibronectin, are used for the preparation of anisotropic self-assembled monolayers (SAM gradients) to study the whole-population migratory behavior of metastatic breast cancer cells (MDA-MB-231 cells). Ile-Gly-Asp-Gln-(IGDQ)-exposing SAMs sustain the adhesion of MDA-MB-231 cells by triggering focal adhesion kinase phosphorylation, similarly to the analogous Gly-Arg-Gly-Asp-(GRGD)-terminating surfaces. However, the biological responses of different cell lines interfaced with the SAM gradients show that only those exposing the IGDQ sequence induce significant migration of MDA-MB-231 cells. In particular, the observed migratory behavior suggests the presence of cell subpopulations associated with a "stationary" or a "migratory" phenotype, the latter determining a considerable cell migration at the sub-cm length scale. These findings are of great importance as they suggest for the first time an active role of biological surfaces exposing the IGD motif in the multicomponent orchestration of cellular signaling involved in the metastatic progression.

ATP-binding Cassette Subfamily C Member 5 (ABCC5) Functions as an Efflux Transporter of Glutamate Conjugates and Analogs

The ubiquitous efflux transporter ABCC5 (ATP-binding cassette subfamily C member 5) is present at high levels in the blood-brain barrier, neurons, and glia, but its in vivo substrates and function are not known. Using untargeted metabolomic screens, we show that Abcc5(-/-) mice accumulate endogenous glutamate conjugates in several tissues, but brain in particular. The abundant neurotransmitter N-acetylaspartylglutamate was 2.4-fold higher in Abcc5(-/-) brain. The metabolites that accumulated in Abcc5(-/-) tissues were depleted in cultured cells that overexpressed human ABCC5. In a vesicular membrane transport assay, ABCC5 also transported exogenous glutamate analogs, like the classic excitotoxic neurotoxins kainic acid, domoic acid, and NMDA; the therapeutic glutamate analog ZJ43; and, as previously shown, the anti-cancer drug methotrexate. Glutamate conjugates and analogs are of physiological relevance because they can affect the function of glutamate, the principal excitatory neurotransmitter in the brain. After CO2 asphyxiation, several immediate early genes were expressed at lower levels in Abcc5(-/-) brains than in wild type brains, suggesting altered glutamate signaling. Our results show that ABCC5 is a general glutamate conjugate and analog transporter that affects the disposition of endogenous metabolites, toxins, and drugs.

Deregulation of miR-128 in ovarian cancer promotes cisplatin resistance

OBJECTIVE

Platinum-based chemotherapy is the standard treatment in advanced ovarian cancer, but most patients will relapse with drug-resistant disease. MicroRNAs have been demonstrated to function in chemoresistance in cancers. In this study, we focused on the role of miR-128 in cisplatin-resistant ovarian cancer.

MATERIALS AND METHODS

The expression of miR-128 RNA and its targeted genes, the polycomb ring finger oncogene Bmi-1 and ATP-binding cassette subfamily C member 5 (ABCC5), were investigated in the epithelial ovarian cancer cells and ovarian carcinomas.

RESULTS

miR-128 expression was significantly reduced in the cisplatin-resistant human epithelial ovarian cancer cell line SKOV3/CP compared with parental SKOV3 cells and decreased upon treatment with cisplatin in a concentration-dependent manner in SKOV3, OVCAR3, and PEO14 cells. Overexpression of miR-128 resensitized SKOV3/CP cells to cisplatin and reduced the expression of cisplatin-resistant-related proteins ABCC5 and Bmi-1, whereas miR-128 inhibitors increased cisplatin resistance in SKOV3 cells. Cisplatin combined with miR-128 agomirs inhibited the growth of SKOV3/CP xenograft tumors more effectively than cisplatin alone. Diminished expression of ABCC5 and Bmi-1 and higher cisplatin concentrations were observed in tumor tissue of mice treated with miR-128 agomirs in addition to cisplatin.

CONCLUSIONS

Taken together, our findings suggest that miR-128 may act as a promising therapeutic target for improvement of tumor sensitivity to cisplatin.

N-lactoyl-amino acids are ubiquitous metabolites that originate from CNDP2-mediated reverse proteolysis of lactate and amino acids

Despite technological advances in metabolomics, large parts of the human metabolome are still unexplored. In an untargeted metabolomics screen aiming to identify substrates of the orphan transporter ATP-binding cassette subfamily C member 5 (ABCC5), we identified a class of mammalian metabolites, N-lactoyl-amino acids. Using parallel protein fractionation in conjunction with shotgun proteomics on fractions containing N-lactoyl-Phe-forming activity, we unexpectedly found that a protease, cytosolic nonspecific dipeptidase 2 (CNDP2), catalyzes their formation. N-lactoyl-amino acids are ubiquitous pseudodipeptides of lactic acid and amino acids that are rapidly formed by reverse proteolysis, a process previously considered to be negligible in vivo. The plasma levels of these metabolites strongly correlate with plasma levels of lactate and amino acid, as shown by increased levels after physical exercise and in patients with phenylketonuria who suffer from elevated Phe levels. Our approach to identify unknown metabolites and their biosynthesis has general applicability in the further exploration of the human metabolome.

A First Step toward Personalized Medicine in Osteosarcoma: Pharmacogenetics as Predictive Marker of Outcome after Chemotherapy-Based Treatment

PURPOSE

Overall survival in patients with osteosarcoma is only 60%. Poor response to chemotherapy is the dominant risk factor for poor survival. Pharmacogenetic research can offer possibilities to optimize treatment and improve outcome. We applied a pathway-based approach to evaluate the cumulative effect of genes involved in the metabolism of cisplatin and doxorubicin in relationship to clinical outcome.

EXPERIMENTAL DESIGN

We included 126 patients with osteosarcoma. To comprehensively assess common genetic variation in the 54 genes selected, linkage disequilibrium (LD; r(2) = 0.8)-based tag-single nucleotide polymorphisms (SNP) strategy was used. A final set of 384 SNPs was typed using Illumina Beadarray platform. SNPs significantly associated with 5-year progression-free survival (PFS) were replicated in another 64 patients with osteosarcoma.

RESULTS

We identified five variants in FasL, MSH2, ABCC5, CASP3, and CYP3A4 that were associated with 5-year PFS. Risk stratification based on the combined effects of the risk alleles showed a significant improvement of 5-year PFS. Patients that carried no or only one risk allele had a 5-year PFS of 100% compared with a 5-year PFS of 84.4% for carriers of two or three risk alleles, 66.7% PFS if a patient carried four to five alleles, and a 5-year PFS of 41.8% for patients with >5 risk alleles (P < 0.001).

CONCLUSIONS

We identified several genes that showed association with PFS in patients with osteosarcoma. These pharmacogenetic risk factors might be useful to predict treatment outcome and to stratify patients immediately after diagnosis and offer the possibility to improve treatment and outcome.

Granulocytic immune infiltrates are essential for the efficient formation of breast cancer liver metastases

Introduction

Breast cancer cells display preferences for specific metastatic sites including the bone, lung and liver. Metastasis is a complex process that relies, in part, on interactions between disseminated cancer cells and resident/infiltrating stromal cells that constitute the metastatic microenvironment. Distinct immune infiltrates can either impair the metastatic process or conversely, assist in the seeding, colonization and growth of disseminated cancer cells.

Methods

Using in vivo selection approaches, we previously isolated 4T1-derived breast cancer cells that preferentially metastasize to these organs and tissues. In this study, we examined whether the propensity of breast cancer cells to metastasize to the lung, liver or bone is associated with and dependent on distinct patterns of immune cell infiltration. Immunohistocytochemistry and immunohistofluorescence approaches were used to quantify innate immune cell infiltrates within distinct metastases and depletion of Gr1⁺ (Ly-6C and Ly-6G) or specifically Ly-6G⁺ cells was performed to functionally interrogate the role of Ly-6G⁺ infiltrates in promoting metastasis to these organs.

Results

We show that T lymphocytes (CD3⁺), myeloid-derived (Gr-1⁺) cells and neutrophils (Ly-6G⁺ or NE⁺) exhibit the most pronounced recruitment in lung and liver metastases, with markedly less recruitment within bone metastatic lesions. Interestingly, these infiltrating cell populations display different patterns of localization within soft tissue metastases. T lymphocytes and granulocytic immune infiltrates are localized around the periphery of liver metastases whereas they were dispersed throughout the lung metastases. Furthermore, Gr-1⁺ cell-depletion studies demonstrate that infiltrating myeloid-derived cells are essential for the formation of breast cancer liver metastases but dispensable for metastasis to the lung and bone. A specific role for the granulocytic component of the innate immune infiltrate was revealed through Ly-6G⁺ cell-depletion experiments, which resulted in significantly impaired formation of liver metastases. Finally, we demonstrate that the CD11b⁺/Ly-6G⁺ neutrophils that infiltrate and surround the liver metastases are polarized toward an N2 phenotype, which have previously been shown to enhance tumor growth and metastasis.

Conclusions

Our results demonstrate that the liver-metastatic potential of breast cancer cells is heavily reliant on interactions with infiltrating Ly-6G⁺ cells within the liver microenvironment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-015-0558-3) contains supplementary material, which is available to authorized users.

DENND2B activates Rab13 at the leading edge of migrating cells and promotes metastatic behavior

DENND2B, in a complex with the Rab13 effector MICAL-L2, activates Rab13 at the cell periphery, promoting the dynamic remodeling of the cell’s leading edge during tumor cell migration both in vitro and in vivo.

The small guanosine triphosphatase Rab13 functions in exocytic vesicle trafficking in epithelial cells. Alterations in Rab13 activity have been observed in human cancers, yet the mechanism of Rab13 activation and its role in cancer progression remain unclear. In this paper, we identify the DENN domain protein DENND2B as the guanine nucleotide exchange factor for Rab13 and develop a novel Förster resonance energy transfer–based Rab biosensor to reveal activation of Rab13 by DENND2B at the leading edge of migrating cells. DENND2B interacts with the Rab13 effector MICAL-L2 at the cell periphery, and this interaction is required for the dynamic remodeling of the cell’s leading edge. Disruption of Rab13-mediated trafficking dramatically limits the invasive behavior of epithelial cells in vitro and the growth and migration of highly invasive cancer cells in vivo. Thus, blocking Rab13 activation by DENND2B may provide a novel target to limit the spread of epithelial cancers.

cGMP signaling as a target for the prevention and treatment of breast cancer

One in eight women in the United States will be diagnosed with invasive breast cancer in her lifetime. Advances in therapeutic strategies, diagnosis, and improved awareness have resulted in a significant reduction in breast cancer related mortality. However, there is a continued need for more effective and less toxic drugs for both the prevention and the treatment of breast cancer in order to see a continued decline in the morbidity and mortality associated with this disease. Recent studies suggest that the cGMP signaling pathway may be aberrantly regulated in breast cancer. As such, this pathway may serve as a source of novel targets for future breast cancer drug discovery efforts. This review provides an overview of cGMP signaling in normal physiology and in breast cancer as well as current strategies being investigated for targeting this pathway in breast cancer.

SF3B1 mutations are associated with alternative splicing in uveal melanoma

Uveal melanoma, the most common eye malignancy, causes severe visual morbidity and is fatal in approximately 50% of patients. Primary uveal melanoma can be cured by surgery or radiotherapy, but the metastatic disease is treatment refractory. To understand comprehensively uveal melanoma genetics, we conducted single-nucleotide polymorphism arrays and whole-genome sequencing on 12 primary uveal melanomas. We observed only approximately 2,000 predicted somatic single-nucleotide variants per tumor and low levels of aneuploidy. We did not observe an ultraviolet radiation DNA damage signature, but identified SF3B1 mutations in three samples and a further 15 mutations in an extension cohort of 105 samples. SF3B1 mutations were associated with good prognosis and were rarely coincident with BAP1 mutations. SF3B1 encodes a component of the spliceosome, and RNA sequencing revealed that SF3B1 mutations were associated with differential alternative splicing of protein coding genes, including ABCC5 and UQCC, and of the long noncoding RNA CRNDE.

SIGNIFICANCE

Our data show that despite its dismal prognosis, uveal melanoma is a relatively simple genetic disease characterized by recurrent chromosomal losses and gains and a low mutational burden. We show that SF3B1 is recurrently mutated in uveal melanoma, and the mutations are associated with aberrant alternative splicing.

Bone-Targeted Agents for the Management of Breast Cancer Patients with Bone Metastases

Despite advances in adjuvant therapy for breast cancer, bone remains the most common site of recurrence. The goal of therapy for these patients is palliative and focused on maximizing the duration and quality of their life, while concurrently minimizing any disease or treatment-related complications. Bone metastases predispose patients to reduced survival, pain, impaired quality of life and the development of skeletal-related events. With an increased understanding of the pathophysiology of bone metastasis, effective treatments for their management have evolved and are now in widespread clinical use. This article will discuss the pathogenesis of bone metastases and review the key clinical evidence for the efficacy and safety of currently available systemic bone-targeted therapies in breast cancer patients with an emphasis on bisphosphonates and the receptor activator of nuclear factor kappa B ligand (RANKL) inhibitors. We will also discuss novel strategies and therapies currently in development.