Astrocytes promote progression of breast cancer metastases to the brain via a KISS1-mediated autophagy

Crosstalk between breast cancer-derived microRNAs and brain microenvironmental cells in breast cancer brain metastasis

Breast cancer is the most frequent malignancy in women, constituting 15.2% of all new cancers diagnosed in the United States. Distant breast cancer metastasis accounts for the majority of breast cancer-related deaths; brain metastasis is the third most common site for metastatic breast cancer but is associated with worst prognosis of approximately eight months of survival. Current treatment options for breast cancer brain metastasis (BCBM) are limited and ineffective. To help identify new and effective therapies for BCBM, it is important to investigate the mechanisms by which breast cancer cells metastasize to the brain and thrive in the brain microenvironment. To this end, studies have reported that primary breast tumor cells can prime brain microenvironmental cells, including, astrocytes and microglia, to promote the formation of BCBM through the release of extracellular vesicle-microRNAs (miRNAs). Breast tumor-derived miRNAs can also promote breast cancer cell invasion through the blood-brain barrier by disrupting the integrity of the brain microvascular endothelial cells. In this review, we summarize current literature on breast cancer-derived BCBM-promoting miRNAs, cover their roles in the complex steps of BCBM particularly their interactions with microenvironmental cells within the brain metastatic niche, and finally discuss their therapeutic applications in the management of BCBM.

The Role of Microglia in Brain Metastases: Mechanisms and Strategies

Brain metastases and related complications are one of the major fatal factors in cancer. Patients with breast cancer, lung cancer, and melanoma are at a high risk of developing brain metastases. However, the mechanisms underlying the brain metastatic cascade remain poorly understood. Microglia, one of the major resident macrophages in the brain parenchyma, are involved in multiple processes associated with brain metastasis, including inflammation, angiogenesis, and immune modulation. They also closely interact with metastatic cancer cells, astrocytes, and other immune cells. Current therapeutic approaches against metastatic brain cancers, including small-molecule drugs, antibody-coupled drugs (ADCs), and immune-checkpoint inhibitors (ICIs), have compromised efficacy owing to the impermeability of the blood-brain barrier (BBB) and complex brain microenvironment. Targeting microglia is one of the strategies for treating metastatic brain cancer. In this review, we summarize the multifaceted roles of microglia in brain metastases and highlight them as potential targets for future therapeutic interventions.

The role of microRNAs in brain metastasis

Brain metastasis (BM) is the most common type of brain tumor and frequently foreshadows disease progression and poor overall survival with patients having a median survival of 6 months. 70,000 new cases of BM are diagnosed each year in the United States (US) and the incidence rate for BM is increasing with improved detection. MicroRNAs (miRNAs) are small non-coding RNAs that serve as critical regulators of gene expression and can act as powerful oncogenes and tumor suppressors. MiRNAs have been heavily implicated in cancer and proposed as biomarkers or therapeutic targets or agents. In this review, we summarize an extensive body of scientific work investigating the role of microRNAs in BM. We discuss miRNA dysregulation, functions, targets, and mechanisms of action in BM and present the current standing of miRNAs as biomarkers and potential therapeutics for BM. We conclude with future directions of miRNA basic and clinical research in BM.

Metastasis suppressor genes in clinical practice: are they druggable?

Since the identification of NM23 (now called NME1) as the first metastasis suppressor gene (MSG), a small number of other gene products and non-coding RNAs have been identified that suppress specific parameters of the metastatic cascade, yet which have little or no ability to regulate primary tumor initiation or maintenance. MSG can regulate various pathways or cell biological functions such as those controlling mitogen-activated protein kinase pathway mediators, cell-cell and cell-extracellular matrix protein adhesion, cytoskeletal architecture, G-protein-coupled receptors, apoptosis, and transcriptional complexes. One defining facet of this gene class is that their expression is typically downregulated, not mutated, in metastasis, such that any effective therapeutic intervention would involve their re-expression. This review will address the therapeutic targeting of MSG, once thought to be a daunting task only facilitated by ectopically re-expressing MSG in metastatic cells in vivo. Examples will be cited of attempts to identify actionable oncogenic pathways that might suppress the formation or progression of metastases through the re-expression of specific metastasis suppressors.

Navigating the Blood-Brain Barrier: Challenges and Therapeutic Strategies in Breast Cancer Brain Metastases

Breast cancer (BC) is the most common cancer in women, with metastatic BC being responsible for the highest number of deaths. A frequent site for BC metastasis is the brain. Brain metastasis derived from BC involves the cooperation of multiple genetic, epigenetic, angiogenic, and tumor-stroma interactions. Most of these interactions provide a unique opportunity for development of new therapeutic targets. Potentially targetable signaling pathways are Notch, Wnt, and the epidermal growth factor receptors signaling pathways, all of which are linked to driving BC brain metastasis (BCBM). However, a major challenge in treating brain metastasis remains the blood-brain barrier (BBB). This barrier restricts the access of unwanted molecules, cells, and targeted therapies to the brain parenchyma. Moreover, current therapies to treat brain metastases, such as stereotactic radiosurgery and whole-brain radiotherapy, have limited efficacy. Promising new drugs like phosphatase and kinase modulators, as well as BBB disruptors and immunotherapeutic strategies, have shown the potential to ease the disease in preclinical studies, but remain limited by multiple resistance mechanisms. This review summarizes some of the current understanding of the mechanisms involved in BC brain metastasis and highlights current challenges as well as opportunities in strategic designs of potentially successful future therapies.

The tumor-nerve circuit in breast cancer

It is well established that innervation is one of the updated hallmarks of cancer and that psychological stress promotes the initiation and progression of cancer. The breast tumor environment includes not only fibroblasts, adipocytes, endothelial cells, and lymphocytes but also neurons, which is increasingly discovered important in breast cancer progression. Peripheral nerves, especially sympathetic, parasympathetic, and sensory nerves, have been reported to play important but different roles in breast cancer. However, their roles in the breast cancer progression and treatment are still controversial. In addition, the brain is one of the favorite sites of breast cancer metastasis. In this review, we first summarize the innervation of breast cancer and its mechanism in regulating cancer growth and metastasis. Next, we summarize the neural-related molecular markers in breast cancer diagnosis and treatment. In addition, we review drugs and emerging technologies used to block the interactions between nerves and breast cancer. Finally, we discuss future research directions in this field. In conclusion, the further research in breast cancer and its interactions with innervated neurons or neurotransmitters is promising in the clinical management of breast cancer.

Role of mitochondrial stress and the NLRP3 inflammasome in lung diseases

BACKGROUND

As an organelle essential for intracellular energy supply, mitochondria are involved in intracellular metabolism and inflammation, and cell death. The interaction of mitochondria with the NLRP3 inflammasome in the development of lung diseases has been extensively studied. However, the exact mechanism by which mitochondria mediate the activation of the NLRP3 inflammasome and trigger lung disease is still unclear.

METHODS

The literatures related to mitochondrial stress, NLRP3 inflammasome and lung diseases were searched in PubMed.

RESULTS

This review aims to provide new insights into the recently discovered mitochondrial regulation of the NLRP3 inflammasome in lung diseases. It also describes the crucial roles of mitochondrial autophagy, long noncoding RNA, micro RNA, altered mitochondrial membrane potential, cell membrane receptors, and ion channels in mitochondrial stress and regulation of the NLRP3 inflammasome, in addition to the reduction of mitochondrial stress by nuclear factor erythroid 2-related factor 2 (Nrf2). The effective components of potential drugs for the treatment of lung diseases under this mechanism are also summarized.

CONCLUSION

This review provides a resource for the discovery of new therapeutic mechanisms and suggests ideas for the development of new therapeutic drugs, thus promoting the rapid treatment of lung diseases.

KISS1 metastasis suppressor in tumor dormancy: a potential therapeutic target for metastatic cancers?

Present therapeutic approaches do not effectively target metastatic cancers, often limited by their inability to eliminate already-seeded non-proliferative, growth-arrested, or therapy-resistant tumor cells. Devising effective approaches targeting dormant tumor cells has been a focus of cancer clinicians for decades. However, progress has been limited due to limited understanding of the tumor dormancy process. Studies on tumor dormancy have picked up pace and have resulted in the identification of several regulators. This review focuses on KISS1, a metastasis suppressor gene that suppresses metastasis by keeping tumor cells in a state of dormancy at ectopic sites. The review explores mechanistic insights of KISS1 and discusses its potential application as a therapeutic against metastatic cancers by eliminating quiescent cells or inducing long-term dormancy in tumor cells.

Advances in Brain Metastases Diagnosis: Non-coding RNAs As Potential Biomarkers

Brain metastasis is considered the most common brain tumor. They arise from different primary cancers. The most common primary tumors giving brain metastases include breast, colorectal, lung, melanoma, and renal cancer. Depending only on history, physical examination, and conventional imaging modalities makes brain tumors diagnosis difficult. Rapid and non-invasive promising modalities could diagnose and differentiate between different brain metastases without exposing the patients to unnecessary brain surgeries for biopsies. One of these promising modalities is non-coding RNAs (ncRNAs). NcRNAs can determine brain metastases' prognosis, chemoresistance, and radioresistance. It also helps us to understand the pathophysiology of brain metastases development. Additionally, ncRNAs may work as potential therapeutic targets for brain metastases treatment and prevention. Herein, we present deregulated ncRNAs in different brain metastases, including microRNAs and long non-coding RNAs (lncRNAs), such as gastric adenocarcinoma, colorectal, breast, melanoma, lung, and prostate cancer. Additionally, we focus on serum and cerebrospinal fluid (CSF) expression of these ncRNAs in patients with brain metastases compared to patients with primary tumors. Moreover, we discuss the role of ncRNAs in modulating the immune response in the brain microenvironment. More clinical studies are encouraged to assess the specificity and sensitivity of these ncRNAs.

The Role of Autophagy in Breast Cancer Metastasis

Patient morbidity and mortality is significantly increased in metastatic breast cancer. The metastasis process of breast cancer is very complicated and is delicately controlled by various factors. Autophagy is one of the important regulatory factors affecting metastasis in breast cancer by engaging in cell mobility, metabolic adaptation, tumor dormancy, and cancer stem cells. Here, we discuss the effects of autophagy on metastasis in breast cancer and assess the potential use of autophagy modulators for metastasis treatment.

5'-tRF-GlyGCC promotes breast cancer metastasis by increasing fat mass and obesity-associated protein demethylase activity

tRNA-derived fragments (tRFs) are a class of regulatory non-coding RNAs that play essential biological functions in cancer and stress-induced diseases. Several lines of evidence suggest that 5'-tRF-GlyGCC participates in tumor progression; however, its molecular mechanisms remain unclear. In this study, we explored the function of 5'-tRF-GlyGCC in breast cancer (BC) progression and studied the related potential molecular mechanisms. 5'-tRF-GlyGCC expression increased in human BC, and it promoted the proliferation, migration, and invasion of BC cells in vitro and tumor growth and metastasis in vivo. 5'-tRF-GlyGCC was found for the first time to bind directly to fat mass and obesity-associated proteins, and increase the activity of FTO demethylase, reducing eIF4G1 methylation, inhibiting autophagy, and promoting BC proliferation and metastasis. These findings suggest that 5'-tRF-GlyGCC might be a therapeutic target for treating BC.

Mesenchymal stem cells derived from adipose tissue accelerate the progression of colon cancer by inducing a MTCAF phenotype via ICAM1/STAT3/AKT axis

Previous studies have shown that the risk of colon cancer is greatly increased in people with obesity, and fat content in colorectal cancer tissue is increased in people with obesity. As an important part of tumor microenvironment, adipose-derived mesenchymal stem cells (MSCs) are also another important source of cancer-associated fibroblasts (CAFs), which may be one of the important mechanisms of affecting tumor progression. However, the mechanism is poorly defined. In the present study, CAFs were transformed from MSCs [MSC-transformed CAFs (MTCAFs)] by co-culturing with HCT116 cells. Bioinformatics and Western blotting analysis indicated a positive correlation between intercellular adhesion molecule-1(ICAM-1) and the progression of colon cancer. In clinical colon cancer specimens, we found that ICAM-1 was highly expressed and related to shorter disease-free survival, which might act as an indication for the progression of clinical colon cancer. Our data showed that ICAM-1 secreted from MTCAFs could positively promote the proliferation, migration, and invasion of colon cancer cells by activating signal transducer and activator of transcription 3 (STAT3) and Serine/threonine-protein kinase (AKT) signaling and that blocking ICAM-1 in MTCAFs reversed these effects. We further verified that ICAM-1 secreted from MTCAFs promoted tumor progression in vivo. Taken together, ICAM-1 plays a critical role in regulating tumor growth and metastasis, which could be a potential therapeutic target in colon cancer.

Structural Characterization and Anti-breast Cancer Activity in vitro of a Novel Polysaccharide From Cymbopogon citratus

Cymbopogon citratus is an important functional food, widely used for flavoring in Africa and South America. In this study, a novel high-molecular-weight polysaccharide (CCP) from C. citratus was extracted, and its structural characteristics and anti-breast cancer activity in vitro were investigated. CCP contained both α and β configurations and mainly composed of galactose (36.89%), arabinose (23.97%), glucose (18.35%) and rhamnose (9.36%) with an average molecular weight of 1.98 × 10⁶ Da. The main glycosyl residues of CCP detected by methylation analysis were 1,3,6-linked Galp, 1,3-linked Glcp, 1,5-linked Araf , T-Araf , and T-Rhap. In vitro experiments suggested that CCP significantly inhibited the proliferation of MDA-MB-231 cells, decreased the expressions of cyclin D1 and CDK4 and stocked cells at G₀/G₁ phase. Meanwhile, the typical morphological features of apoptotic cells were also observed. Combining with the consequences of Annexin V-FITC/PI staining, Hoechst 33258 staining and western blot analysis, CCP induced apoptosis of MDA-MB-231 cells by triggering the Fas/FasL-mediated death receptor pathway. Overall, these results provide a theoretical basis for the application of C. citratus polysaccharide as a potential anti-breast cancer agent in functional food and medicine.

Chemokines in Triple-Negative Breast Cancer Heterogeneity: New Challenges for Clinical Implications

Tumor heterogeneity is a hallmark of cancer and one of the primary causes of resistance to therapies. Triple-negative breast cancer (TNBC), which accounts for 15% to 20% of all breast cancers and is the most aggressive subtype, is very diverse, connected to metastatic potential and response to therapy. It is a very diverse disease at the molecular, pathologic, and clinical levels. TNBC is substantially more likely to recur and has a worse overall survival rate following diagnosis than other breast cancer subtypes. Chemokines, low molecular weight proteins that stimulate chemotaxis, have been shown to control the cues responsible for TNBC heterogeneity. In this review, we have focused on tumor heterogeneity and the role of chemokines in modulating tumor heterogeneity, since this is the most critical issue in treating TNBC. Additionally, we examined numerous cues mediated by chemokine networks that contribute to the heterogeneity of TNBC. Recent developments in our knowledge of the chemokine networks that regulate TNBC heterogeneity may pave the door for developing difficult-to-treat TNBC treatment options.

Light-switchable diphtherin transgene system combined with losartan for triple negtative breast cancer therapy based on nano drug delivery system

Breast cancer is a common malignancy in women. The abnormally dense collagen network in breast cancer forms a therapeutic barrier that hinders the penetration and anti-tumor effect of drugs. To overcome this hurdle, we adopted a therapeutic strategy to treat breast cancer which combined a light-switchable transgene system and losartan. The light-switchable transgene system could regulate expression of the diphtheria toxin A fragment (DTA) gene with a high on/off ratio under blue light and had great potential for spatiotemporally controllable gene expression. We developed a nanoparticle drug delivery system to achieve tumor microenvironment-responsive and targeted delivery of DTA-encoded plasmids (pDTA) to tumor sites via dual targeting to cluster of differentiation-44 and α_vβ₃ receptors. In vivo studies indicated that the combination of pDTA and losartan reduce the concentration of collagen type I from 5.9 to 1.9 µg/g and decreased the level of active transforming growth factor-β by 75.0% in tumor tissues. Moreover, deeper tumor penetration was achieved, tumor growth was inhibited, and the survival rate was increased. Our combination strategy provides a novel and practical method for clinical treatment of breast cancer.

Insights into the Steps of Breast Cancer-Brain Metastases Development: Tumor Cell Interactions with the Blood-Brain Barrier

Brain metastases (BM) represent a growing problem for breast cancer (BC) patients. Recent studies have demonstrated a strong impact of the BC molecular subtype on the incidence of BM development. This study explores the interaction between BC cells of different molecular subtypes and the blood–brain barrier (BBB). We compared the ability of BC cells of different molecular subtypes to overcome several steps (adhesion to the brain endothelium, disruption of the BBB, and invasion through the endothelial layer) during cerebral metastases formation, in vitro as well as in vivo. Further, the impact of these cells on the BBB was deciphered at the molecular level by transcriptome analysis of the triple-negative (TNBC) cells themselves as well as of hBMECs after cocultivation with BC cell secretomes. Compared to luminal BC cells, TNBC cells have a greater ability to influence the BBB in vitro and consequently develop BM in vivo. The brain-seeking subline and parental TNBC cells behaved similarly in terms of adhesion, whereas the first showed a stronger impact on the brain endothelium integrity and increased invasive ability. The comparative transcriptome revealed potential brain-metastatic-specific key regulators involved in the aforementioned processes, e.g., the angiogenesis-related factors TNXIP and CXCL1. In addition, the transcriptomes of the two TNBC cell lines strongly differed in certain angiogenesis-associated factors and in several genes related to cell migration and invasion. Based on the present study, we hypothesize that the tumor cell’s ability to disrupt the BBB via angiogenesis activation, together with increased cellular motility, is required for BC cells to overcome the BBB and develop brain metastases.

Autophagy: a multifaceted player in the fate of sperm

BACKGROUND

Autophagy is an intracellular catabolic process of degrading and recycling proteins and organelles to modulate various physiological and pathological events, including cell differentiation and development. Emerging data indicate that autophagy is closely associated with male reproduction, especially the biosynthetic and catabolic processes of sperm. Throughout the fate of sperm, a series of highly specialized cellular events occur, involving pre-testicular, testicular and post-testicular events. Nonetheless, the most fundamental question of whether autophagy plays a protective or harmful role in male reproduction, especially in sperm, remains unclear.

OBJECTIVE AND RATIONALE

We summarize the functional roles of autophagy in the pre-testicular (hypothalamic–pituitary–testis (HPG) axis), testicular (spermatocytogenesis, spermatidogenesis, spermiogenesis, spermiation) and post-testicular (sperm maturation and fertilization) processes according to the timeline of sperm fate. Additionally, critical mechanisms of the action and clinical impacts of autophagy on sperm are identified, laying the foundation for the treatment of male infertility.

SEARCH METHODS

In this narrative review, the PubMed database was used to search peer-reviewed publications for summarizing the functional roles of autophagy in the fate of sperm using the following terms: ‘autophagy’, ‘sperm’, ‘hypothalamic–pituitary–testis axis’, ‘spermatogenesis’, ‘spermatocytogenesis’, ‘spermatidogenesis’, ‘spermiogenesis’, ‘spermiation’, ‘sperm maturation’, ‘fertilization’, ‘capacitation’ and ‘acrosome’ in combination with autophagy-related proteins. We also performed a bibliographic search for the clinical impact of the autophagy process using the keywords of autophagy inhibitors such as ‘bafilomycin A1’, ‘chloroquine’, ‘hydroxychloroquine’, ‘3-Methyl Adenine (3-MA)’, ‘lucanthone’, ‘wortmannin’ and autophagy activators such as ‘rapamycin’, ‘perifosine’, ‘metformin’ in combination with ‘disease’, ‘treatment’, ‘therapy’, ‘male infertility’ and equivalent terms. In addition, reference lists of primary and review articles were reviewed for additional relevant publications. All relevant publications until August 2021 were critically evaluated and discussed on the basis of relevance, quality and timelines.

OUTCOMES

(i) In pre-testicular processes, autophagy-related genes are involved in the regulation of the HPG axis; and (ii) in testicular processes, mTORC1, the main gate to autophagy, is crucial for spermatogonia stem cell (SCCs) proliferation, differentiation, meiotic progression, inactivation of sex chromosomes and spermiogenesis. During spermatidogenesis, autophagy maintains haploid round spermatid chromatoid body homeostasis for differentiation. During spermiogenesis, autophagy participates in acrosome biogenesis, flagella assembly, head shaping and the removal of cytoplasm from elongating spermatid. After spermatogenesis, through PDLIM1, autophagy orchestrates apical ectoplasmic specialization and basal ectoplasmic specialization to handle cytoskeleton assembly, governing spermatid movement and release during spermiation. In post-testicular processes, there is no direct evidence that autophagy participates in the process of capacitation. However, autophagy modulates the acrosome reaction, paternal mitochondria elimination and clearance of membranous organelles during fertilization.

WIDER IMPLICATIONS

Deciphering the roles of autophagy in the entire fate of sperm will provide valuable insights into therapies for diseases, especially male infertility.

Identification of Protein Biomarker Signatures for Acute Myeloid Leukemia (AML) Using Both Nontargeted and Targeted Approaches

Acute myeloid leukemia (AML) is characterized by an increasing number of clonal myeloid blast cells which are incapable of differentiating into mature leukocytes. AML risk stratification is based on genetic background, which also serves as a means to identify the optimal treatment of individual patients. However, constant refinements are needed, and the inclusion of significant measurements, based on the various omics approaches that are currently available to researchers/clinicians, have the potential to increase overall accuracy with respect to patient management. Using both nontargeted (label-free mass spectrometry) and targeted (multiplex immunoassays) proteomics, a range of proteins were found to be significantly changed in AML patients with different genetic backgrounds. The inclusion of validated proteomic biomarker panels could be an important factor in the prognostic classification of AML patients. The ability to measure both cellular and secreted analytes, at diagnosis and during the course of treatment, has advantages in identifying transforming biological mechanisms in patients, assisting important clinical management decisions.

Association of human breast cancer CD44-/CD24- cells with delayed distant metastasis

Tumor metastasis remains the main cause of breast cancer-related deaths, especially delayed breast cancer distant metastasis. The current study assessed the frequency of CD44^-/CD24^- breast cancer cells in 576 tissue specimens for associations with clinicopathological features and metastasis and investigated the underlying molecular mechanisms. The results indicated that higher frequency (≥19.5%) of CD44^-/CD24^- cells was associated with delayed postoperative breast cancer metastasis. Furthermore, CD44^-/CD24^-triple negative breast cancer (TNBC) cells spontaneously converted into CD44⁺/CD24^-cancer stem cells (CSCs) with properties similar to CD44⁺/CD24^-CSCs from primary human breast cancer cells and parental TNBC cells in terms of stemness marker expression, self-renewal, differentiation, tumorigenicity, and lung metastasis in vitro and in NOD/SCID mice. RNA sequencing identified several differentially expressed genes (DEGs) in newly converted CSCs and RHBDL2, one of the DEGs, expression was upregulated. More importantly, RHBDL2 silencing inhibited the YAP1/USP31/NF-κB signaling and attenuated spontaneous CD44^-/CD24^- cell conversion into CSCs and their mammosphere formation. These findings suggest that the frequency of CD44^-/CD24^- tumor cells and RHBDL2 may be valuable for prognosis of delayed breast cancer metastasis, particularly for TNBC.

Breast cancer brain metastasis: insight into molecular mechanisms and therapeutic strategies

Breast cancer is one of the most prevalent malignancies in women worldwide. Early-stage breast cancer is considered a curable disease; however, once distant metastasis occurs, the 5-year overall survival rate of patients becomes significantly reduced. There are four distinct metastatic patterns in breast cancer: bone, lung, liver and brain. Among these, breast cancer brain metastasis (BCBM) is the leading cause of death; it is highly associated with impaired quality of life and poor prognosis due to the limited permeability of the blood-brain barrier and consequent lack of effective treatments. Although the sequence of events in BCBM is universally accepted, the underlying mechanisms have not yet been fully elucidated. In this review, we outline progress surrounding the molecular mechanisms involved in BCBM as well as experimental methods and research models to better understand the process. We further discuss the challenges in the management of brain metastases, as well as providing an overview of current therapies and highlighting innovative research towards developing novel efficacious targeted therapies.

GLIPR1 and SPARC expression profile reveals a signature associated with prostate Cancer Brain metastasis

Despite advances in treatment of lethal prostate cancer, the incidence of prostate cancer brain metastases is increasing. In this sense, we analyzed the molecular profile, as well as the functional consequences involved in the reciprocal interactions between prostate tumor cells and human astrocytes. We observed that the DU145 cells, but not the LNCaP cells or the RWPE-1 cells, exhibited more pronounced, malignant and invasive phenotypes along their interactions with astrocytes. Moreover, global gene expression analysis revealed several genes that were differently expressed in our co-culture models with the overexpression of GLIPR1 and SPARC potentially representing a molecular signature associated with the invasion of central nervous system by prostate malignant cells. Further, these results were corroborated by immunohistochemistry and in silico analysis. Thus, we conjecture that the data here presented may increase the knowledge about the molecular mechanisms associated with the invasion of CNS by prostate malignant cells.

Infrared spectroscopic imaging study of BV-2 microglia altering tumor cell biological activity and cellular fraction

Tumor brain metastasis is a severe threat to patients' neurological function, in which microglia may be involved in the process of tumor cell metastasis among nerve cells. Our study focused on the interaction between microglia and breast and lung cancer cells. Changes in the proliferation and migration ability of cocultured tumor cells were examined; synchrotron radiation-based fourier transform infrared microspectroscopy (SR-FTIR) was used to detect changes in the structures and contents of biomolecules within the tumor cells. The experimental results showed that the proliferation and migration ability of tumor cells increased after coculture, and the structures and contents of biological macromolecules in tumor cells changed. The absorption peak positions of the amide Ⅱ and amide Ⅰ bands observed for the four kinds of tumor cells changed, and the absorption intensities were significantly enhanced, indicating changes in the secondary structures and contents of proteins in tumor cells, which may be the root cause of the change in tumor cell characteristics. Therefore, the metabolites of microglia may be involved in the progression of tumor cells in the nervous system. In this study, we focused on the interaction between microglia and tumor cells by using SR-FTIR and provided a new understanding of the mechanism of brain metastasis.

Regulation of breast cancer metastasis signaling by miRNAs

Despite the decline in death rate from breast cancer and recent advances in targeted therapies and combinations for the treatment of metastatic disease, metastatic breast cancer remains the second leading cause of cancer-associated death in U.S. women. The invasion-metastasis cascade involves a number of steps and multitudes of proteins and signaling molecules. The pathways include invasion, intravasation, circulation, extravasation, infiltration into a distant site to form a metastatic niche, and micrometastasis formation in a new environment. Each of these processes is regulated by changes in gene expression. Noncoding RNAs including microRNAs (miRNAs) are involved in breast cancer tumorigenesis, progression, and metastasis by post-transcriptional regulation of target gene expression. miRNAs can stimulate oncogenesis (oncomiRs), inhibit tumor growth (tumor suppressors or miRsupps), and regulate gene targets in metastasis (metastamiRs). The goal of this review is to summarize some of the key miRNAs that regulate genes and pathways involved in metastatic breast cancer with an emphasis on estrogen receptor α (ERα+) breast cancer. We reviewed the identity, regulation, human breast tumor expression, and reported prognostic significance of miRNAs that have been documented to directly target key genes in pathways, including epithelial-to-mesenchymal transition (EMT) contributing to the metastatic cascade. We critically evaluated the evidence for metastamiRs and their targets and miRNA regulation of metastasis suppressor genes in breast cancer progression and metastasis. It is clear that our understanding of miRNA regulation of targets in metastasis is incomplete.

The Network of Cytokines in Brain Metastases

Brain metastases are the most common of all intracranial tumors and a major cause of death in patients with cancer. Cytokines, including chemokines, interferons, interleukins, lymphokines, and tumor necrosis factors are key regulators in the formation of brain metastases. They regulate the infiltration of different cellular subsets into the tumor microenvironment and affect the therapeutic outcomes in patients. Elucidating the cancer cell-cytokine interactions in the setting of brain metastases is crucial for the development of more accurate diagnostics and efficacious therapies. In this review, we focus on cytokines that are found in the tumor microenvironment of brain metastases and elaborate on their trends of expression, regulation, and roles in cellular recruitment and tumorigenesis. We also explore how cytokines can alter the anti-tumor response in the context of brain metastases and discuss ways through which cytokine networks can be manipulated for diagnosis and treatment.

Autophagy-mediated tumor cell survival and progression of breast cancer metastasis to the brain

Brain metastases represent a substantial amount of morbidity and mortality in breast cancer (BC). Metastatic breast tumor cells committed to brain metastases are unique because they escape immune surveillance, can penetrate the blood-brain barrier, and also adapt to the brain tissue microenvironment (TME) for colonization and outgrowth. In addition, dynamic intracellular interactions between metastatic cancer cells and neighboring astrocytes in the brain are thought to play essential roles in brain tumor progression. A better understanding of the above mechanisms will lead to developing more effective therapies for brain metastases. Growing literature suggests autophagy, a conserved lysosomal degradation pathway involved in cellular homeostasis under stressful conditions, plays essential roles in breast tumor metastatic transformation and brain metastases. Cancer cells must adapt under various microenvironmental stresses, such as hypoxia, and nutrient (glucose) deprivation, in order to survive and progress. Clinical studies reveal that tumoral expression of autophagy-related proteins is higher in brain metastasis compared to primary breast tumors. In this review, we outline the molecular mechanisms underlying autophagy-mediated BC cell survival and metastasis to the brain.

Regulators at Every Step-How microRNAs Drive Tumor Cell Invasiveness and Metastasis

Tumor cell invasiveness and metastasis are the main causes of mortality in cancer. Tumor progression is composed of many steps, including primary tumor growth, local invasion, intravasation, survival in the circulation, pre-metastatic niche formation, and metastasis. All these steps are strictly controlled by microRNAs (miRNAs), small non-coding RNA that regulate gene expression at the post-transcriptional level. miRNAs can act as oncomiRs that promote tumor cell invasion and metastasis or as tumor suppressor miRNAs that inhibit tumor progression. These miRNAs regulate the actin cytoskeleton, the expression of extracellular matrix (ECM) receptors including integrins and ECM-remodeling enzymes comprising matrix metalloproteinases (MMPs), and regulate epithelial-mesenchymal transition (EMT), hence modulating cell migration and invasiveness. Moreover, miRNAs regulate angiogenesis, the formation of a pre-metastatic niche, and metastasis. Thus, miRNAs are biomarkers of metastases as well as promising targets of therapy. In this review, we comprehensively describe the role of various miRNAs in tumor cell migration, invasion, and metastasis.

Regulators at Every Step—How microRNAs Drive Tumor Cell Invasiveness and Metastasis

Tumor cell invasiveness and metastasis are the main causes of mortality in cancer. Tumor progression is composed of many steps, including primary tumor growth, local invasion, intravasation, survival in the circulation, pre-metastatic niche formation, and metastasis. All these steps are strictly controlled by microRNAs (miRNAs), small non-coding RNA that regulate gene expression at the post-transcriptional level. miRNAs can act as oncomiRs that promote tumor cell invasion and metastasis or as tumor suppressor miRNAs that inhibit tumor progression. These miRNAs regulate the actin cytoskeleton, the expression of extracellular matrix (ECM) receptors including integrins and ECM-remodeling enzymes comprising matrix metalloproteinases (MMPs), and regulate epithelial–mesenchymal transition (EMT), hence modulating cell migration and invasiveness. Moreover, miRNAs regulate angiogenesis, the formation of a pre-metastatic niche, and metastasis. Thus, miRNAs are biomarkers of metastases as well as promising targets of therapy. In this review, we comprehensively describe the role of various miRNAs in tumor cell migration, invasion, and metastasis.

The Signaling Duo CXCL12 and CXCR4: Chemokine Fuel for Breast Cancer Tumorigenesis

Simple Summary

Breast cancer remains the most common malignancy in women. In this review, we explore the role of the CXCL12/CXCR4 pathway in breast cancer. We show that the CXCL12/CXCR4 cascade is involved in nearly every aspect of breast cancer tumorigenesis including proliferation, cell motility and distant metastasis. Moreover, we summarize current knowledge about the CXCL12/CXCR4-targeted therapies. Due to the critical roles of this pathway in breast cancer and other malignancies, we believe that audiences in different fields will find this overview helpful.

Abstract

The CXCL12/CXCR4 signaling pathway has emerged in the recent years as a key player in breast cancer tumorigenesis. This pathway controls many aspects of breast cancer development including cancer cell proliferation, motility and metastasis to all target organs. Moreover, the CXCL12/CXCR4 cascade affects both immune and stromal cells, creating tumor-supporting microenvironment. In this review, we examine state-of-the-art knowledge about detrimental roles of the CXCL12/CXCR4 signaling, discuss its therapeutic potential and suggest further research directions beneficial both for basic research and personalized medicine in breast cancer.

Kisspeptin preserves mitochondrial function by inducing mitophagy and autophagy in aging rat brain hippocampus and human neuronal cell line

It has become amply clear that mitochondrial function defined by quality, quantity, dynamics, homeostasis, and regulated by mitophagy and mitochondrial biogenesis is a critical metric of human aging and disease. As a consequence, therapeutic interventions that can improve mitochondrial function can have a profound impact on human health and longevity. Kisspeptins are neuropeptides belonging to the family of metastasis suppressors that are known to regulate functions like fertility, reproduction, and metabolism. Using SKNSH cell line, hippocampus explant cultures and hippocampus of aging Wistar rat models, we show that Kisspeptin-10 (Kp) induces autophagy and mitophagy via calcium, Ca²⁺/CaM-dependent protein kinase kinase β (CaMKKβ), AMP-activated protein kinase (AMPK), and Unc-51 like autophagy activating kinase (ULK1) signaling pathway that is independent of mammalian target of rapamycin (mTOR). Intriguingly, Kp administration in vivo also results in the enhancement of mitochondrial number, complex I activity, and Adenosine Triphosphate (ATP) levels. This study uncovers potential effects of Kp in protecting mitochondrial health and as a possible therapeutic intervention to hippocampus associated impairments such as memory, cognitive aging, and other diseases linked to mitochondrial dysfunction.

Autophagy and Tumour Chemotherapy

Chemotherapy is an important means of treating malignant tumours. The main role of chemotherapy drugs is to induce cell death. However, the apoptotic pathways of many tumour cells are often severely impaired, leading to failure of chemotherapy-induced apoptosis. With the in-depth study of autophagy in recent years, this process has been found to play an important role in the chemoresistance of tumours. Autophagy may have different effects on tumour cells depending on the specific environment. In addition, tumour stem cells and the tumour microenvironment are closely related to tumour recurrence and metastasis. It is also important to study the role of autophagy in tumour stem cells and the microenvironment to investigate chemotherapy resistance.

A Novel Risk Model Based on Autophagy Pathway Related Genes for Survival Prediction in Lung Adenocarcinoma

Background

Autophagy has a principal role in mediating tumor cell metabolism. However, the role of autophagy-pathway-related genes (APRGs) as prognostic markers remains obscure in lung adenocarcinoma (LUAD). More potential prognostic biomarkers are needed to deepen our understanding to explore the prognostic role of APRGs in LUAD.

Material/Methods

We used The Cancer Genome Atlas (TCGA) database to identify differentially expressed APRGs. Cox proportional hazard regression was used to identify prognostic APRGs, and then a risk model was constructed. The efficacy of the risk model was confirmed using a testing group. Lastly, we explored mutational signatures of prognostic of APRGs. T-tests were used to analyze all the expression patterns of genes by SPSS 19.0.

Results

Using TCGA database, 5 differently expressed APRGs were identified in LUAD patients, and functional enrichment analyze of the genes that were closely associated with the survival status in LUAD patients. Cox proportional hazard regression was facilitated to identify 9 APRGs (CCR2, LAMP1, RELA, ATG12, ATG9A, NCKAP1, ATG10, DNAJB9, and MBTPS2). Multivariate Cox proportional hazards regression analyses further identified 5 key prognostic APRGs (CCR2, LAMP1, RELA, ATG12, and MBTPS2) that were closely related to the survival status in LUAD. Then the prognostic scores based on the 5 genes as independent prognostic indicators were constructed for overall survival (OS) of LUAD patients; area under the curve (AUC) values >0.70 (all P<0.05). The efficacy of prognostic scores was confirmed by data from the testing group and showed significant differences between the low-risk and the high-risk groups for OS (P<0.05).

Conclusions

The risk model based on the construction of 5 APRGs can predict the prognosis of patients with LUAD, which may potentially predict prognostic signatures for LUAD.

KISS1 in metastatic cancer research and treatment: potential and paradoxes

The significance of KISS1 goes beyond its original discovery as a metastasis suppressor. Its function as a neuropeptide involved in diverse physiologic processes is more well studied. Enthusiasm regarding KISS1 has cumulated in clinical trials in multiple fields related to reproduction and metabolism. But its cancer therapeutic space is unsettled. This review focuses on collating data from cancer and non-cancer fields in order to understand shared and disparate signaling that might inform clinical development in the cancer therapeutic and biomarker space. Research has focused on amino acid residues 68-121 (kisspeptin 54), binding to the KISS1 receptor and cellular responses. Evidence and counterevidence regarding this canonical pathway require closer look at the covariates so that the incredible potential of KISS1 can be realized.

The KiSS-1/GPR54 system: Essential roles in physiological homeostasis and cancer biology

KiSS-1, first identified as an anti-metastasis gene in melanoma, encodes C-terminally amidated peptide products, including kisspeptin-145, kisspeptin-54, kisspeptin-14, kisspeptin-13 and kisspeptin-10. These products are endogenous ligands coupled to G protein-coupled receptor 54 (GPR54)/hOT7T175/AXOR12. To date, the regulatory activities of the KiSS-1/GPR54 system, such as puberty initiation, antitumor metastasis, fertility in adulthood, hypothalamic-pituitary-gonadal axis (HPG axis) feedback, and trophoblast invasion, have been investigated intensively. Accumulating evidence has demonstrated that KiSS-1 played a key role in reproduction and served as a promising biomarker relative to the diagnosis, identification of therapeutic targets and prognosis in various carcinomas, while few studies have systematically summarized its subjective factors and concluded the functions of KiSS-1/GPR54 signaling in physiology homeostasis and cancer biology. In this review, we retrospectively summarized the regulators of the KiSS-1/GPR54 system in different animal models and reviewed its functions according to physiological homeostasis regulations and above all, cancer biology, which provided us with a profound understanding of applying the KiSS-1/GPR54 system into medical applications.

MicroRNA 345 (miR345) regulates KISS1-E-cadherin functional interaction in breast cancer brain metastases

Brain metastases manifest the advanced stage of breast cancer disease with poor prognosis for patient survival. Recent reports demonstrate that some therapeutic agents can activate the expression of several breast cancer-associated genes, whose products are involved in the onset and development of brain metastases. In this study, we discovered a functional link between KISS1 and E-cadherin that could be observed in both primary brain metastatic lesions and paired cell lines, such as parental CN34TGL and MDA-MB-231 and their respective brain metastatic subclones CN34Brm2Ctgl and MDA-MB-231Br. Remarkably, expression of KISS1 and E-cadherin genes consistently showed an inverse correlation in all of the above cell/tissue types. While E-cadherin expression was strongly upregulated in metastatic clones isolated from blood and brain, the levels of this protein in parental MDA-MB-231 cell line was low. Furthermore, E-cadherin upregulation can be artificially induced in MDA-MB-231Br and CN34Brm2Ctgl cell populations by knocking down KISS1 expression directly or through overexpressing the miR345 mimic. In the aggregate, our data suggest that the tumor microenvironment, which controls breast cancer spreading via miR345-regulated KISS1 expression, might modulate metastatic spreading by a mechanism(s) involving upregulation of E-cadherin production.

Role of the tumor microenvironment in regulating the anti-metastatic effect of KISS1

KISS1, a metastasis suppressor gene, has been shown to block metastasis without affecting primary tumor formation. Loss of KISS1 leads to invasion and metastasis in multiple cancers, which is the leading cause of cancer morbidity and mortality. The discovery of KISS1 has provided a ray of hope for early clinical diagnosis and for designing effective treatments targeting metastatic cancer. However, this goal requires greater holistic understanding of its mechanism of action. In this review, we go back into history and highlight some key developments, from the discovery of KISS1 to its role in regulating multiple physiological processes including cancer. We discuss key emerging roles for KISS1, specifically interactions with tissue microenvironment to promote dormancy and regulation of tumor cell metabolism, acknowledged as some of the key players in tumor progression and metastasis. We finally discuss strategies whereby KISS1 might be exploited clinically to treat metastasis.

Autophagy-associated circRNA circCDYL augments autophagy and promotes breast cancer progression

BACKGROUND

Although both circular RNAs (circRNAs) and autophagy are associated with the function of breast cancer (BC), whether circRNAs regulate BC progression via autophagy remains unknown. In this study, we aim to explore the regulatory mechanisms and the clinical significance of autophagy-associated circRNAs in BC.

METHODS

Autophagy associated circRNAs were screened by circRNAs deep sequencing and validated by qRT-PCR in BC tissues with high- and low- autophagic level. The biological function of autophagy associated circRNAs were assessed by plate colony formation, cell viability, transwells, flow cytometry and orthotopic animal models. For mechanistic study, RNA immunoprecipitation, circRNAs pull-down, Dual luciferase report assay, Western Blot, Immunofluorescence and Immunohistochemical staining were performed.

RESULTS

An autophagy associated circRNA circCDYL was elevated by 3.2 folds in BC tissues as compared with the adjacent non-cancerous tissues, and circCDYL promoted autophagic level in BC cells via the miR-1275-ATG7/ULK1 axis; Moreover, circCDYL enhanced the malignant progression of BC cells in vitro and in vivo. Clinically, increased circCDYL in the tumor tissues and serum of BC patients was associated with higher tumor burden, shorter survival and poorer clinical response to therapy.

CONCLUSIONS

circCDYL promotes BC progression via the miR-1275-ATG7/ULK1-autophagic axis and circCDYL could act as a potential prognostic and predictive molecule for breast cancer patients.

The network of non-coding RNAs and their molecular targets in breast cancer

Background

Non-coding RNAs are now recognized as fundamental components of the cellular processes. Non-coding RNAs are composed of different classes, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Their detailed roles in breast cancer are still under scrutiny.

Main body

We systematically reviewed from recent literature the many functional and physical interactions of non-coding RNAs in breast cancer. We used a data driven approach to establish the network of direct, and indirect, interactions. Human curation was essential to de-convolute and critically assess the experimental approaches in the reviewed articles. To enrol the scientific papers in our article cohort, due to the short time span (shorter than 5 years) we considered the journal impact factor rather than the citation number.

The outcome of our work is the formal establishment of different sub-networks composed by non-coding RNAs and coding genes with validated relations in human breast cancer. This review describes in a concise and unbiased fashion the core of our current knowledge on the role of lncRNAs, miRNAs and other non-coding RNAs in breast cancer.

Conclusions

A number of coding/non-coding gene interactions have been investigated in breast cancer during recent years and their full extent is still being established. Here, we have unveiled some of the most important networks embracing those interactions, and described their involvement in cancer development and in its malignant progression.

Alpha-lipoic acid inhibits lung cancer growth via mTOR-mediated autophagy inhibition

Lung cancer is the leading cause of cancer‐related death, and there remains a need for novel therapies for this malignancy. Here, we examined the effects of alpha‐lipoic acid (LA), a drug used for treating human diabetic complications, on lung cancer growth. We report that LA limited lung cancer growth in xenograft mice and reduced lung cancer A549 cell viability. We observed autophagy activation in human lung cancers, and report that LA inactivated autophagy in A549 cells. In addition, LA activated mammalian target of rapamycin (mTOR)/p70S6K signaling. Inhibition of mTOR with rapamycin reversed LA‐induced inactivation of autophagy and abolished LA‐induced suppression of A549 cell viability. Altogether, the data suggest that LA exerts an anti‐lung cancer effect through mTOR‐mediated inhibition of autophagy, and thus LA may have therapeutic potential for lung cancer management.

microRNAs Orchestrate Pathophysiology of Breast Cancer Brain Metastasis: Advances in Therapy

Brain metastasis (BM) predominantly occurs in triple-negative (TN) and epidermal growth factor 2 (HER2)-positive breast cancer (BC) patients, and currently, there is an unmet need for the treatment of these patients. BM is a complex process that is regulated by the formation of a metastatic niche. A better understanding of the brain metastatic processes and the crosstalk between cancer cells and brain microenvironment is essential for designing a novel therapeutic approach. In this context, the aberrant expression of miRNA has been shown to be associated with BM. These non-coding RNAs/miRNAs regulate metastasis through modulating the formation of a metastatic niche and metabolic reprogramming via regulation of their target genes. However, the role of miRNA in breast cancer brain metastasis (BCBM) is poorly explored. Thus, identification and understanding of miRNAs in the pathobiology of BCBM may identify a novel candidate miRNA for the early diagnosis and prevention of this devastating process. In this review, we focus on understanding the role of candidate miRNAs in the regulation of BC brain metastatic processes as well as designing novel miRNA-based therapeutic strategies for BCBM.

KISS1 in breast cancer progression and autophagy

Tumor suppressors are cellular proteins typically expressed in normal (non-cancer) cells that not only regulate such cellular functions as proliferation, migration and adhesion, but can also be secreted into extracellular space and serve as biomarkers for pathological conditions or tumor progression. KISS1, a precursor for several shorter peptides, known as metastin (Kisspeptin-54), Kisspeptin-14, Kisspeptin-13 and Kisspeptin-10, is one of those metastasis suppressor proteins, whose expression is commonly downregulated in the metastatic tumors of various origins. The commonly accepted role of KISS1 in metastatic tumor progression mechanism is the ability of this protein to suppress colonization of disseminated cancer cells in distant organs critical for the formation of the secondary tumor foci. Besides, recent evidence suggests involvement of KISS1 in the mechanisms of tumor angiogenesis, autophagy and apoptosis regulation, suggesting a possible role in both restricting and promoting cancer cell invasion. Here, we discuss the role of KISS1 in regulating metastases, the link between KISS1 expression and the autophagy-related biology of cancer cells and the perspectives of using KISS1 as a potential diagnostic marker for cancer progression as well as a new anti-cancer therapeutics.

BIRC7 promotes epithelial-mesenchymal transition and metastasis in papillary thyroid carcinoma through restraining autophagy

Papillary thyroid carcinoma (PTC) is the most common cancer of the endocrine system, which is usually associated with a favorable therapeutic response and prognosis. However, metastatic spreading occurs in around 5% of the PTC patients. Identification of molecular markers could early predict the metastatic potential, which is essential for reducing the patient's overtreatment. Baculoviral IAP Repeat Containing 7 (BIRC7) is an inhibitor of apoptosis protein (IAP) family gene that is known to be linked to tumor progression, but its role in the setting of PTC metastasis remains unknown. This study, therefore, aims to explore the role of BIRC7 in the metastasis and autophagy of PTC and elucidate its underlying molecular mechanisms. BIRC7 expression was assessed in fresh samples of human PTC and normal tissues via qRT-PCR and immunohistochemistry. In addition, BIRC7 was overexpressed and silenced in PTC cell lines followed by transmission electron microscopy, western blotting, immunofluorescence microscopy, wound healing and invasion assays. We further explored the relevance of BIRC7 in vivo using a tumor xenograft model. Our results demonstrated that BIRC7 plays a pro-invasive role in PTC. BIRC7 expression is significantly upregulated in PTC compared with matched thyroid normal tissues. In addition, we found that BIRC7 knockdown induced a significant reduction in PTC cell EMT and metastasis in vitro and in vivo, while overexpression of BIRC7 markedly enhanced PTC cell migration and invasion. Moreover, our data showed that BIRC7 was able to suppress autophagy through modulating the expression of ATG5 and BECN1, and that this suppression is responsible for BIRC7 silence induced suppression of EMT and metastasis of PTC cell. We further found that targeting both BIRC7 and mTOR enhances autophagy in PTC cells and to achieve synergistic antimetastatic efficacy in vitro and in vivo. These findings indicate that the suppression of autophagy by BIRC7 drives the invasion and metastasis of PTC cells, thus suggesting that the activation of autophagy may inhibit metastasis of PTC with high BIRC7 expression.

Kisspeptin-Activated Autophagy Independently Suppresses Non-Glucose-Stimulated Insulin Secretion from Pancreatic β-Cells

Previous studies have demonstrated the important role of kisspeptin in impaired glucose-stimulated insulin secretion (GSIS). In addition, it was reported that the activation of autophagy in pancreatic β-cells decreases insulin secretion by selectively degrading insulin granules. However, it is currently unknown whether kisspeptin suppresses GSIS in β-cells by activating autophagy. To investigate the involvement of autophagy in kisspeptin-regulated insulin secretion, we overexpressed Kiss1 in NIT-1 cells to mimic the long-term exposure of pancreatic β-cells to kisspeptin during type 2 diabetes (T2D). Interestingly, our data showed that although kisspeptin potently decreases the intracellular proinsulin and insulin ((pro)insulin) content and insulin secretion of NIT-1 cells, autophagy inhibition using bafilomycin A1 and Atg5 siRNAs only rescues basal insulin secretion, not kisspeptin-impaired GSIS. We also generated a novel in vivo model to investigate the long-term exposure of kisspeptin by osmotic pump. The in vivo data demonstrated that kisspeptin lowers GSIS and (pro)insulin levels and also activated pancreatic autophagy in mice. Collectively, our data demonstrated that kisspeptin suppresses both GSIS and non-glucose-stimulated insulin secretion of pancreatic β-cells, but only non-glucose-stimulated insulin secretion depends on activated autophagic degradation of (pro)insulin. Our study provides novel insights for the development of impaired insulin secretion during T2D progression.

Malignant invasion of the central nervous system: the hidden face of a poorly understood outcome of prostate cancer

Malignancies of the central nervous system include primary brain tumors and brain metastases, the latter being the major cause of intracranial neoplasms in adults. Although prostate cancer (PCa) brain metastases are not the most common source, recent data show that the relevance of prostate cancer brain metastases (PCBM) cannot be neglected. In this review, we focus on the molecular repertory as well as on the phenotypical similarities between PCBM and primary PCa, such as the cellular evolution and the maintenance of androgen-receptor expression. Moreover, the simultaneous occurrence of PCBM with other PCa metastatic sites and the significance of the clinical heterogeneity of the disease are also discussed. In addition, a potential relationship between the heterogeneous behavior exhibited by PCBM and the co-occurrence of malignant cell clusters with distinct genetic profiles is also hypothesized, as well as the prominent role of astrocytes in the establishment of PCBM.

The biology and therapeutic management of melanoma brain metastases

The recent years have seen significant progress in the development of systemic therapies to treat patients with advanced melanoma. Use of these new treatment modalities, which include immune checkpoint inhibitors and small molecule BRAF inhibitors, lead to increased overall survival and better outcomes. Although revolutionary, these therapies are often less effective against melanoma brain metastases, and frequently the CNS is the major site of treatment failure. The development of brain metastases remains a serious complication of advanced melanoma that is associated with significant morbidity and mortality. New approaches to both prevent the development of brain metastases and treat established disease are urgently needed. In this review we will outline the mechanisms underlying the development of melanoma brain metastases and will discuss how new insights into metastasis biology are driving the development of new therapeutic strategies. Finally, we will describe the latest data from the ongoing clinical trials for patients with melanoma brain metastases.