Central and peripheral nervous systems: master controllers in cancer metastasis

The relationship between the tumor and its innervation: historical, methodical, morphological, and functional assessments - A minireview

The acceptance of the tumor as a non-isolated structure within the organism has opened a space for the study of a wide spectrum of potential direct and indirect interactions, not only between the tumor tissue and its vicinity, but also between the tumor and its macroenvironment, including the nervous system. Although several lines of evidence have implicated the nervous system in tumor growth and progression, for many years, researchers believed that tumors lacked innervation and the notion of indirect neuro-neoplastic interactions via other systems (e.g., immune, or endocrine) predominated. The original idea that tumors are supplied not only by blood and lymphatic vessels, but also autonomic and sensory nerves that may influence cancer progression, is not a recent phenomenon. Although in the past, mainly due to the insufficiently sensitive methodological approaches, opinions regarding the presence of nerves in tumors were inconsistent. However, data from the last decade have shown that tumors are able to stimulate the formation of their own innervation by processes called neo-neurogenesis and neo-axonogenesis. It has also been shown that tumor infiltrating nerves are not a passive, but active components of the tumor microenvironment and their presence in the tumor tissue is associated with an aggressive tumor phenotype and correlates with poor prognosis. The aim of the present review was to 1) summarize the available knowledge regarding the course of tumor innervation, 2) present the potential mechanisms and pathways for the possible induction of new nerve fibers into the tumor microenvironment, and 3) highlight the functional significance/consequences of the nerves infiltrating the tumors.

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.

Nerves in gastrointestinal cancer: from mechanism to modulations

Maintenance of gastrointestinal health is challenging as it requires balancing multifaceted processes within the highly complex and dynamic ecosystem of the gastrointestinal tract. Disturbances within this vibrant environment can have detrimental consequences, including the onset of gastrointestinal cancers. Globally, gastrointestinal cancers account for ~19% of all cancer cases and ~22.5% of all cancer-related deaths. Developing new ways to more readily detect and more efficiently target these malignancies are urgently needed. Whereas members of the tumour microenvironment, such as immune cells and fibroblasts, have already been in the spotlight as key players of cancer initiation and progression, the importance of the nervous system in gastrointestinal cancers has only been highlighted in the past few years. Although extrinsic innervations modulate gastrointestinal cancers, cells and signals from the gut's intrinsic innervation also have the ability to do so. Here, we shed light on this thriving field and discuss neural influences during gastrointestinal carcinogenesis. We focus on the interactions between neurons and components of the gastrointestinal tract and tumour microenvironment, on the neural signalling pathways involved, and how these factors affect the cancer hallmarks, and discuss the neural signatures in gastrointestinal cancers. Finally, we highlight neural-related therapies that have potential for the management of gastrointestinal cancers.

The theory of tumor ecosystem

Cancer cells can be conceived as “living organisms” interacting with cellular or non‐cellular components in the host internal environment, not only the local tumor microenvironment but also the distant organ niches, as well as the immune, nervous and endocrine systems, to construct a self‐sustainable tumor ecosystem. With increasing evidence for the systemic tumor‐host interplay, we predict that a new era of cancer therapy targeting the ecosystemic vulnerability of human malignancies has come. Revolving around the tumor ecosystem scoped as different hierarchies of primary, regional, distal and systemic onco‐spheres, we comprehensively review the tumor‐host interaction among cancer cells and their local microenvironment, distant organ niches, immune, nervous and endocrine systems, highlighting material and energy flow with tumor ecological homeostasis as an internal driving force. We also substantiate the knowledge of visualizing, modelling and subtyping this dynamically intertwined network with recent technological advances, and discuss ecologically rational strategies for more effective cancer therapies.

Is Infantile Hemangioma a Neuroendocrine Tumor?

Infantile hemangioma (IH) is the most common infantile tumor, affecting 5–10% of newborns. Propranolol, a nonselective β-adrenergic receptor (ADRB) antagonist, is currently the first-line treatment for severe IH; however, both its mechanism of action and its main cellular target remain poorly understood. Since betablockers can antagonize the effect of natural ADRB agonists, we postulated that the catecholamine produced in situ in IH may have a role in the propranolol response. By quantifying catecholamines in the IH tissues, we found a higher amount of noradrenaline (NA) in untreated proliferative IHs than in involuted IHs or propranolol-treated IHs. We further found that the first three enzymes of the catecholamine biosynthesis pathway are expressed by IH cells and that their levels are reduced in propranolol-treated tumors. To study the role of NA in the pathophysiology of IH and its response to propranolol, we performed an in vitro angiogenesis assay in which IH-derived endothelial cells, pericytes and/or telocytes were incorporated. The results showed that the total tube formation is sensitive to propranolol only when exogenous NA is added in the three-cell model. We conclude that the IH’s sensitivity to propranolol depends on crosstalk between the endothelial cells, pericytes and telocytes in the context of a high local amount of local NA.

Chronic stress promotes breast carcinoma metastasis by accumulating myeloid-derived suppressor cells through activating β-adrenergic signaling

Numerous studies have found that chronic stress could promote tumor progression and this may be related to inhibtion of immune system. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells with immunosuppressive activity. MDSCs may represent a key link between chronic stress and tumor progression. However, the role of stress-induced MDSCs in breast cancer progression is unclear. The present study showed that pre-exposure of chronic stress could lead to MDSCs elevation and facilitated breast cancer metastasis in tumor-bearing mice. Adoptive transfer of MDSCs could significantly increase lung metastatic foci. In contrast, lung metastasis could be alleviated by depleting endogenous MDSCs with Gr-1 antibody. The concentration of norepinephrine in serum and the expression of tyrosine hydroxylase in bone marrow could be significantly elevated by chronic stress. Moreover, propranolol, an inhibitor of β-adrenergic signaling, could inhibit breast carcinoma metastasis and prevent the expansion of chronic stress-induced MDSCs. Further study revealed that the expressions of IL-6 and JAK/STAT3 signaling pathways were upregulated by chronic stress in mice, and this upregulation could be inhibited by propranolol. Blocking the IL-6 signal or inhibiting the activation of the JAK/STAT3 signaling pathway could reduce tumor growth and metastasis by attenuating the accumulation of MDSCs in vivo. Besides, propranolol inhibited the expression of IL-6 in supernatant of 4T1 cells induced by isoproterenol and reduced the proportion of inducible MDSCs in vitro. Taken together, these data indicated that chronic stress may accumulate MDSCs via activation of β-adrenergic signaling and IL-6/STAT3 pathway, thereby promoting breast carcinoma metastasis.

3D tumor angiogenesis models: recent advances and challenges

The development of blood vessels, referred to as angiogenesis, is an intricate process regulated spatially and temporally through a delicate balance between the qualitative and quantitative expression of pro and anti-angiogenic molecules. As angiogenesis is a prerequisite for solid tumors to grow and metastasize, a variety of tumor angiogenesis models have been formulated to better understand the underlying mechanisms and associated clinical applications. Studies have demonstrated independent mechanisms inducing angiogenesis in tumors such as (a) HIF-1/VEGF mediated paracrine interactions between a cancer cell and endothelial cells, (b) recruitment of progenitor endothelial cells, and (c) vasculogenic mimicry. Moreover, single-cell sequencing technologies have indicated endothelial cell heterogeneity among organ systems including tumor tissues. However, existing angiogenesis models often rely upon normal endothelial cells which significantly differ from tumor endothelial cells exhibiting distinct (epi)genetic and metabolic signatures. Besides, the existence of intra-individual variations necessitates the development of improved tumor vascular model systems for personalized medicine. In the present review, we summarize recent advancements of 3D tumor vascular model systems which include (a) tissue engineering-based tumor models; (b) vascular organoid models, and (c) organ-on-chips and their importance in replicating the tumor angiogenesis along with the associated challenges to design improved models.

Neurobiology of Cancer: the Role of β-Adrenergic Receptor Signaling in Various Tumor Environments

The development and progression of cancer depends on both tumor micro- and macroenvironments. In addition, psychosocial and spiritual “environments” might also affect cancer. It has been found that the nervous system, via neural and humoral pathways, significantly modulates processes related to cancer at the level of the tumor micro- and macroenvironments. The nervous system also mediates the effects of psychosocial and noetic factors on cancer. Importantly, data accumulated in the last two decades have clearly shown that effects of the nervous system on cancer initiation, progression, and the development of metastases are mediated by the sympathoadrenal system mainly via β-adrenergic receptor signaling. Here, we provide a new complex view of the role of β-adrenergic receptor signaling within the tumor micro- and macroenvironments as well as in mediating the effects of the psychosocial and spiritual environments. In addition, we describe potential preventive and therapeutic implications.

The Neuroimmune Axis in the Tumor Microenvironment

Cancer is a complex ecosystem and should be considered in the context of its cellular and molecular microenvironment, which includes the nerves. Peripheral nerves can modulate phenotype and behavior of the malignant cells and thus affect tumor growth and metastasis. Only recently has the role of neuroimmune cross-talk surfaced as a key contributor to cancer progression. However, little is known about the immunomodulatory role of the neuroglial cells in cancer progression and metastasis and the response to therapy. Schwann cells, the principal glial cells of the peripheral nervous system, are now considered to be important players in the tumor microenvironment. They can directly accelerate malignant cell migration and the formation of metastases. Better understanding of the neuroimmune circuits in the tumor milieu will be instrumental in the development of novel therapeutic approaches for the malignancies known to be associated with inflammation and dysregulated immune responses.

Can stress promote the pathophysiology of brain metastases? A critical review of biobehavioral mechanisms

Chronic stress can promote tumor growth and progression through immunosuppressive effects and bi-directional interactions between tumor cells and their microenvironment. β-Adrenergic receptor signaling plays a critical role in mediating stress-related effects on tumor progression. Stress-related mechanisms that modulate the dissemination of tumor cells to the brain have received scant attention. Brain metastases are highly resistant to chemotherapy and contribute considerably to morbidity and mortality in various cancers, occurring in up to 20% of patients in some cancer types. Understanding the mechanisms promoting brain metastasis could help to identify interventions that improve disease outcomes. In this review, we discuss biobehavioral, sympathetic, neuroendocrine, and immunological mechanisms by which chronic stress can impact tumor progression and metastatic dissemination to the brain. The critical role of the inflammatory tumor microenvironment in tumor progression and metastatic dissemination to the brain, and its association with stress pathways are delineated. We also discuss translational implications for biobehavioral and pharmacological interventions.

β2AR-HIF-1α-CXCL12 signaling of osteoblasts activated by isoproterenol promotes migration and invasion of prostate cancer cells

Background

Chronic stress is well known to promote tumor progression, however, little is known whether chronic stress-mediated regulation of osteoblasts contributes to the migration and invasion of metastatic cancer cells.

Methods

The proliferation, migration and invasion of prostate cancer cells were assessed by CCK-8 and transwell assay. HIF-1α expression of osteoblasts and epithelial-mesenchymal transition (EMT) markers of prostate cancer cells were examined by Western blot. The mRNA level of cytokines associated with bone metastasis in osteoblasts and EMT markers in PC-3 and DU145 cells were performed by qRT-PCR. Functional rescue experiment of cells were performed by using siRNA, plasmid transfection and inhibitor treatment.

Results

Isoproterenol (ISO), a pharmacological surrogate of sympathetic nerve activation induced by chronic stress, exhibited no direct effect on migration and invasion of PC-3 and DU145 prostate cancer cells. Whereas, osteoblasts pretreated with ISO promoted EMT, migration and invasion of PC-3 and DU145 cells, which could be inhibited by β2AR inhibitor. Mechanistically, ISO increased the secretion of CXCL12 via the β2AR-HIF-1α signaling in osteoblasts. Moreover, overexpression of HIF-1α osteoblasts promoted migration and invasion of PC-3 and DU145 cells, which was inhibited by addition of recombinant knockdown of CXCR4 in PC-3 and DU145 cells, and inhibiting CXCL12-CXCR4 signaling with LY2510924 blunted the effects of osteoblasts in response to ISO on EMT and migration as well as invasion of PC-3 and DU145 cells.

Conclusions

These findings demonstrated that β2AR-HIF-1α-CXCL12 signaling in osteoblasts facilitates migration and invasion as well as EMT of prostate cancer cells, and may play a potential role in affecting bone metastasis of prostate cancer.

Vasoactive intestinal peptide increases apoptosis of hepatocellular carcinoma by inhibiting the cAMP/Bcl-xL pathway

Vasoactive intestinal peptide (VIP) is a modulator of inflammatory responses. VIP receptors are expressed in several tumor types, such as colorectal carcinoma. The study described herein was conducted to confirm the presence of VIP and its receptors (VPAC1 and VPAC2) in surgically resected hepatocellular carcinoma (HCC) tissues and in the HCC cell line Huh7. The mechanism responsible for apoptosis of HCC cells was then examined because VIP treatment (10^-10  M) significantly suppressed proliferation of Huh7 cells. In examining apoptosis-related proteins, we found caspase-3 to be significantly increased and Bcl-xL and cyclic AMP (cAMP) response element-binding protein (CREB) to be significantly decreased in Huh7 cells cultured with VIP. Furthermore, the CREB level and phosphorylation were reduced. These effects were reversed by the addition of VIP receptor antagonist or cAMP antagonist Rp-cAMPS. Pretreatment with cAMP analogue blocked the increased apoptosis, suggesting that VIP induces apoptosis via a PKA-independent signaling mechanism. Our data indicate that VIP prevents the progression of HCC by apoptosis through the cAMP/Bcl-xL pathway.

Neural regulation of drug resistance in cancer treatment

The treatment of cancer has made great progress. However, drug resistance remains problematic. Multiple physiologic processes of tumor development can be dominated by central and sympathetic nervous systems. The interactions between the nervous system, immune system, and tumor occur consistently and dynamically. Recent evidence suggests that nerves and neural signals are intimately involved in the development of resistance to cancer therapies. In this review, we will provide an overview of the recent progress in this rapidly growing area and discuss the potential new strategies for targeting the neural signaling pathway to improve the effectiveness of chemotherapies, targeted therapies, and immunotherapies.

Identification of the Gene Expression Rules That Define the Subtypes in Glioma

As a common brain cancer derived from glial cells, gliomas have three subtypes: glioblastoma, diffuse astrocytoma, and anaplastic astrocytoma. The subtypes have distinctive clinical features but are closely related to each other. A glioblastoma can be derived from the early stage of diffuse astrocytoma, which can be transformed into anaplastic astrocytoma. Due to the complexity of these dynamic processes, single-cell gene expression profiles are extremely helpful to understand what defines these subtypes. We analyzed the single-cell gene expression profiles of 5057 cells of anaplastic astrocytoma tissues, 261 cells of diffuse astrocytoma tissues, and 1023 cells of glioblastoma tissues with advanced machine learning methods. In detail, a powerful feature selection method, Monte Carlo feature selection (MCFS) method, was adopted to analyze the gene expression profiles of cells, resulting in a feature list. Then, the incremental feature selection (IFS) method was applied to the obtained feature list, with the help of support vector machine (SVM), to extract key features (genes) and construct an optimal SVM classifier. Several key biomarker genes, such as IGFBP2, IGF2BP3, PRDX1, NOV, NEFL, HOXA10, GNG12, SPRY4, and BCL11A, were identified. In addition, the underlying rules of classifying the three subtypes were produced by Johnson reducer algorithm. We found that in diffuse astrocytoma, PRDX1 is highly expressed, and in glioblastoma, the expression level of PRDX1 is low. These rules revealed the difference among the three subtypes, and how they are formed and transformed. These genes are not only biomarkers for glioma subtypes, but also drug targets that may switch the clinical features or even reverse the tumor progression.

Isoproterenol-induced beta-2 adrenergic receptor activation negatively regulates interleukin-2 signaling

Regulation of intracellular signaling pathways in lymphocytes is critical for cell homeostasis and immune response. Interleukin-2 (IL-2), a key regulator of lymphocytes, signals following receptor-ligand engagement and subsequent recruitment and activation of effector proteins including JAKs and STATs. Lymphocytes can also be regulated by the central nervous system through the β2 adrenergic receptor (β2AR) pathway which can affect cell trafficking, proliferation, differentiation, and cytokine production. The cross-talk between these two signaling pathways represents an important mechanism that has yet to be fully elucidated. The present study provides evidence for communication between the IL-2 receptor (IL-2R) and β2AR. Treatment of human lymphoid cell lines with the β2AR agonist isoproterenol (ISO) alone increased cAMP levels and mediated a stimulatory response by activating AKT and ERK to promote cell viability. Interestingly, ISO activation of β2AR also induced threonine phosphorylation of the IL-2Rβ. In contrast, ISO treatment prior to IL-2 stimulation produced an inhibitory signal that disrupted IL-2 induced activation of the JAK/STAT, MEK/ERK, and PI3K pathways by inhibiting the formation of the IL-2R beta-gamma chain complex, and subsequently cell proliferation. Moreover, γ_c-family cytokines-mediated STAT5 activation was also inhibited by ISO. These results suggest a molecular mechanism by which β2AR signaling can both stimulate and suppress lymphocyte responses and thus explain how certain therapeutic agents, such as vasodilators, may impact immune responsiveness.

Chronic psychological stress promotes lung metastatic colonization of circulating breast cancer cells by decorating a pre-metastatic niche through activating β-adrenergic signaling

Numerous studies have indicated that primary tumors induce the formation of a pre-metastatic niche in distant organs by secreting tumor-derived factors. The present study shows that pre-exposure to chronic stress enhanced lung colonization efficiency by circulating tumor cells, suggesting that chronic stress critically influences pre-metastatic lungs before the arrival of disseminated tumor cells. Ablation of the sympathetic nerve function by 6-OHDA or blockage of the β-adrenergic signaling by propranolol remarkably suppressed stress-induced lung metastasis. Depletion of circulating monocytes or lung macrophages strongly abolished stress-induced lung seeding by tumor cells, whereas treatment of mice with the β-adrenergic agonist isoproterenol (ISO) during the pre-metastatic phase promoted the infiltration of macrophages to the lung. Meanwhile, the numbers of monocytes in peripheral blood, spleen, and bone marrow were remarkably increased in response to ISO stimulation. These data indicate that the β-adrenergic signaling promotes lung metastatic colonization by tumor cells through increased output of monocytes in the pre-metastatic phase and infiltration of macrophages into the pre-metastatic lung. Mechanistic studies revealed that ISO stimulation upregulated the expression of CCL2 in pulmonary stromal cells and CCR2 in monocytes/macrophages, leading to the recruitment and infiltration of macrophages into the pre-metastatic lung. By inducing a response of monocytes/macrophages driven by the CCL2/CCR2 axis, stress-related catecholamine may act as a crucial factor in regulating the pre-metastatic niche for and lung colonization by tumor cells. Our data demonstrate that disturbance of host macro-environmental homeostasis has an influence on future metastatic organs. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

β2-AR activation induces chemoresistance by modulating p53 acetylation through upregulating Sirt1 in cervical cancer cells

It has been suggested that β2‐adrenergic receptor (β2‐AR)‐mediated signaling induced by catecholamines regulates the degradation of p53. However, the underlying molecular mechanisms were not known. In the present study, we demonstrated that catecholamines upregulated the expression of silent information regulator 1 (Sirt1) through activating β2‐AR‐mediated signaling pathway, since selective β2‐AR antagonist ICI 118, 551 and non‐selective β‐blocker proprenolol effectively repressed isoproterenol (ISO)‐induced Sirt1 expression. Catecholamines inhibited doxorubicin (DOX)‐induced p53 acetylation and transcription‐activation activities by inducing the expression of Sirt1. Knockdown of the Sirt1 expression by the specific siRNA remarkably blocked the inhibitory effects of ISO on DOX‐induced p53 acetylation. In addition, we demonstrated that catecholamines induced resistance of cervical cancer cells to chemotherapeutics both in vitro and in vivo and that β2‐AR was overexpressed in cervical cancer tissues. Our data suggest that the p53‐dependent, chemotherapeutics‐induced cytotoxicity in cervical cancer cells may be compromised by catecholamines‐induced upregulation of the Sirt1 expression through activating the β2‐AR signaling.

Neuropeptide gastrin-releasing peptide induces PI3K/reactive oxygen species-dependent migration in lung adenocarcinoma cells

Nerve fibers and neurotransmitters have increasingly been shown to have a role in tumor progression. Gastrin-releasing peptide is a neuropeptide linked to tumor aggressiveness, acting as an autocrine tumor growth factor by binding to its receptor, gastrin-releasing peptide receptor, expressed by many tumors. Although neuropeptides have been previously linked to tumor cell proliferation, more recent studies have uncovered roles for neuropeptides in chemotaxis and metastasis. Understanding the precise roles of such peptides in cancer is crucial to optimizing targeted therapy design. We have previously described that gastrin-releasing peptide acts directly as a chemotactic factor for neutrophils, dependent on PI3K, ERK, and p38. In this study, we investigated roles for gastrin-releasing peptide in lung adenocarcinoma. We asked if gastrin-releasing peptide would act as a proliferative and/or chemotactic stimulus for gastrin-releasing peptide receptor-expressing tumor cells. In A549 cells, a non-small cell lung carcinoma line, the treatment with gastrin-releasing peptide leads to activation of AKT and ERK1/2, and production of reactive oxygen species. Gastrin-releasing peptide induced migration of A549 cells, dependent on gastrin-releasing peptide receptor and PI3K, but not ERK. However, no proliferation was observed in these cells in response to gastrin-releasing peptide, and gastrin-releasing peptide did not promote resistance to treatment with a chemotherapy drug. Our results suggest that, similar to what happens in neutrophils, gastrin-releasing peptide is a migratory, rather than a proliferative, stimulus, for non-small cell lung carcinoma cells, indicating a putative role for gastrin-releasing peptide and gastrin-releasing peptide receptor in metastasis.

Effect of the autonomic nervous system on cancer progression depends on the type of tumor: solid are more affected then ascitic tumors

OBJECTIVES

A number of recently published studies have shown that the sympathetic nervous system may influence cancer progression. There are, however, some ambiguities about the role of the parasympathetic nerves in the modulation of growth of different tumor types. Moreover, tumor models used for investigation of the autonomic neurotransmission role in the processes related to the cancer growth and progression are mainly of the solid nature. The knowledge about the nervous system involvement in the modulation of the development and progression of malignant ascites is only fragmental. Therefore, the aim of the present article was to summarize the results of our experimental studies focused on the elucidation of the role of the autonomic nervous system in the modulation of tumor growth in animals. We are summarizing data from studies, in which not only different experimental approaches in order to influence the autonomic neurotransmission, but also different tumor models have been used.

METHODS

Three different types of tumor models, namely solid rat intra-abdominal fibrosarcoma, solid murine subcutaneous melanoma, and rat ascites hepatoma, and three types of interventions have been used in order to modulate the autonomic neurotransmission, specifically chemical sympathectomy, subdiaphragmatic vagotomy, or the electric stimulation of the vagus nerve.

RESULTS

We have proved a strong stimulatory effect of the sympathetic nerves on the development and growth in both solid tumors, rat fibrosarcoma as well as murine melanoma, and significant inhibitory impact on the survival time of tumor-bearing animals. The progression of ascites hepatoma in rats was not influenced by chemical sympathectomy. Modulation of parasympathetic signalization by vagotomy or vagal nerve stimulation does not affect fibrosarcoma and ascites hepatoma growth and survival of the tumor-bearing rats.

CONCLUSIONS

Based on the obtained data, it seems that the solid types of tumors are suitable substrate for the direct action of neurotransmitters released especially from the sympathetic nerves. In contrast, it appears that the malignant ascites are not under the direct autonomic nerves control; however, an indirect action via the immune functions modulation cannot be excluded.

Anxiety and serum catecholamines as predictors of survival and recurrence in hepatocellular carcinoma

OBJECTIVE

Increasing evidence suggests that psychological factors are involved in tumor progression. This study investigated the influence of anxiety and serum catecholamines (CAs) on the prognosis of hepatocellular carcinoma (HCC).

METHOD

We enrolled 110 HCC patients who underwent tumor resection at the Affiliated Hospital of Nantong University, China, in this long-term investigation between 2005 and 2009. We evaluated anxiety using the Hamilton Anxiety Rating Scale (HAMA) and analyzed CA levels using an ELISA kit. We then assessed the association of each of them with overall survival (OS) and time to recurrence (TTR), as well as with other clinical variables.

RESULTS

The HAMA scores significantly correlated with metastasis (P = 0.015), hepatitis B surface antigens (HBsAg) (P = 0.045), and the tumor-node-metastasis stage (P = 0.032), whereas the CA levels also significantly associated with tumor differentiation (P < 0.001). Univariate and multivariate analyses revealed that HAMA scores and CA levels were significant predictors of OS and TTR in HCC patients, with high levels of each being strongly correlated with poor prognosis.

CONCLUSION

The HAMA scores and the CA levels were elevated in HCC patients and correlated with OS and TTR, suggesting that they are candidate prognostic markers of HCC.

The potential anticancer effect of beta-blockers and the genetic variations involved in the interindividual difference

β-ARs are extensively spread in different tissues of our body, which could be activated by neurotransmitters norepinephrine and epinephrine to mediate physiological function and abnormal states including cancer. Recently, β-AR blockers could have significant implications in cancer therapy. But the precise molecular mechanisms are far from being fully understood. Through identifying the β-AR system signal pathways relevant to cancer, we can understand the mechanisms of β-blockers used for cancer treatment. What's more, retrospective clinical data made β-blockers jump out of the traditional field of cardiovascular disease and strengthened our confidence in cancer therapy. At last, genetic studies of β-adrenergic system offered crucial genes to analyze the effects of polymorphisms on cancer susceptibility, therapy response and prognosis of cancer patients.

A Her2-let-7-β2-AR circuit affects prognosis in patients with Her2-positive breast cancer

Background

Our previous studies show that β2-adrenergic receptor (β2-AR) is highly expressed in most Her2-overexpressing breast cancers. However, the mechanisms underlying upregulation of the β2-AR expression in Her2-overexpressing breast cancer cells are not fully understood. The clinical significance of the β2-AR overexpression in breast cancer is unclear.

Methods

Human breast cancer cells MCF-7 and MCF-7/Her2 were transfected with the let-7 mimics or inhibitors. The expression of β2-AR was analyzed by Western blot. The β2-AR status in primary and metastatic sites of breast cancer and the human breast cancer tissue microarrays containing 49 primary tumors and 50 metastatic lymph node tissues was analyzed by immunohistochemistry. The correlation of lymph node metastasis with the β2-AR level was determined in 59 primary tumor tissues from the patients with Her2-positive breast cancer. The clinical prognostic significance of the β2-AR overexpression in the patients with Her2-positive breast cancers was evaluated by a retrospective study.

Results

The let-7f level in Her2-overexpressing breast cancer cells SKBR3 and BT474 was significantly lower than that in MCF-7 cells, which express low level of Her2. Ectopic expression of Her2 in MCF-7 cells (MCF-7/Her2) represses the expression of microRNA let-7f, which is previously identified to regulate baseline β2-AR expression. The treatment with MEK1/2 inhibitors PD98059 or PD184352 effectively restored the let-7f level, suggesting that Her2-overexpression-mediated ERK constitutive activation inhibited let-7f, leading to the upregulation of the β2-AR expression. The transfection with the let-7f mimics markedly downregulated the β2-AR level, whereas the let-7 inhibitor significantly upregulated the β2-AR expression in both parental MCF-7 and MCF-7/Her2 cells. In addition, treatment of MCF-7/Her2 cells with isoproterenol resulted in a concentration-dependent reduction of the let-7f expression, demonstrating that the inhibitory effect of Her2 overexpression on let-7f can be reinforced by agonist-triggered β2-AR activation. We further demonstrate that high level of β2-AR associates with lymph node metastasis and poor outcome in the patients with Her2-positive breast cancer.

Conclusions

The mutual and reciprocal interaction between Her2, β2-AR, and let-7f may maintain a high level of β2-AR in breast cancer cells. Our data suggest that β2-AR may be a new useful biomarker for predicting prognosis in Her2-positive breast cancer and may also be a promising selective therapeutic target for the aggressive subtype of breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1869-6) contains supplementary material, which is available to authorized users.

β2-AR signaling controls trastuzumab resistance-dependent pathway

Currently, trastuzumab resistance is a major clinical problem in the treatment of Her2-overexpressing breast cancer. The underlying molecular mechanisms are not fully understood. Our previous study demonstrates that β2-adrenergic receptor (β2-AR) and Her2 comprise a positive feedback loop in human breast cancer cells and that crosstalk between Her2 and β2-AR affects the bio-behaviors of breast cancer cells, suggesting that the β2-AR activation may be involved in trastuzumab resistance. In this study, we show that the expression of β2-AR, which mediates most catecholamine-induced effects, negatively correlates with trastuzumab response in the patients with Her2-overexpressing breast cancer. Catecholamines potently antagonize the anti-proliferative effects of trastuzumab both in vitro and in vivo. Catecholamine stimulation upregulates the expression of miR-21 and MUC-1 by activating Her2 and STAT3, leading to deficiency of phosphatase and tensin homolog and activation of phosphatidylinositol-3-kinase (PI3K) and Akt. Through inhibition of miR-199a/b-3p, catecholamines induce the mammalian target of rapamycin (mTOR) activation. Thus, trastuzumab resistance-dependent PI3K/Akt/mTOR pathway is controlled by catecholamine-induced β2-AR activation. The data indicate that β2-AR is a reliable molecular marker for prediction of response probability to trastuzumab-based therapy in breast cancer. We also demonstrate that β-blocker propranolol not only enhances the antitumor activities of trastuzumab but also re-sensitizes the resistant cells to trastuzumab. Our retrospective study shows that concurrent treatment of β-blocker and trastuzumab significantly improved progression-free survival and overall survival in the patients with Her2-overexpressing metastatic breast cancer, implicating the possibility for combination therapy with trastuzumab plus β-blocker in Her2-overexpressing breast cancer.

Depressive symptoms and short telomere length are associated with increased mortality in bladder cancer patients

BACKGROUND

Depression is associated with an increased risk of mortality in patients with cancer; it has been hypothesized that depression-associated alterations in cell aging mechanisms, in particular, the telomere/telomerase maintenance system, may underlie this increased risk. We evaluated the association of depressive symptoms and telomere length to mortality and recurrence/progression in 464 patients with bladder cancer.

METHODS

We used the Center for Epidemiologic Studies Depression Scale (CES-D) and Structured Clinical Interview for DSM-IV Disorder (SCID) to assess current depressive symptoms and lifetime major depressive disorder (MDD), respectively, and telomere length was assessed from peripheral blood lymphocytes. Multivariate Cox regression was used to assess the association of depression and telomere length to outcomes and the joint effect of both. Kaplan-Meier plots and log-rank tests were used to compare survival time of subgroups by depression variables and telomere length.

RESULTS

Patients with depressive symptoms (CES-D ≥ 16) had a 1.83-fold [95% confidence interval (CI), 1.08-3.08; P = 0.024] increased risk of mortality compared with patients without depressive symptoms (CES-D < 16) and shorter disease-free survival time (P = 0.004). Patients with both depressive symptoms and lifetime history of MDD were at 4.88-fold (95% CI, 1.40-16.99; P = 0.013) increased risk compared with patients with neither condition. Compared to patients without depressive symptoms and long telomere length, patients with depressive symptoms and short telomeres exhibited a 4-fold increased risk of mortality (HR, 3.96; 95% CI, 1.86-8.41; P = 0.0003) and significantly shorter disease-free survival time (P < 0.001).

CONCLUSION

Short telomere length and depressive symptoms are associated with bladder cancer mortality individually and jointly.

IMPACT

Further investigation of interventions that impact depression and telomere length may be warranted in patients with cancer.

The role of neural-related factors in the metastasis of the gastrointestinal cancer

Neurotransmitters are identified to be endogenous chemicals and act on neurons to transmit signals to each other or to a target cell across synapse. They are involved in many brain functions including analgesia, reward, food intake, metabolism, reproduction, social behaviors, learning, and memory. Recently, sympathetic nerve fibers were detected in many solid tumors including gastrointestinal cancer, supporting the idea that neural system has effects on tumor progression. Neurotransmitters were secreted from the sympathetic nerve fibers and subsequently infiltrated into tumor tissues. Further studies disclosed the different mechanisms of various kinds of neurotransmitters in the progression of carcinogenesis, including tumor cell proliferation, angiogenesis, and tumor invasion and metastasis. Neurotransmitters are mainly subdivided into four types, amino acids, monoamines, peptides, and others, each of which contains multiple chemicals. For this reason, we cannot describe each in detail. In this review, we will focus on several important neurotransmitters including tachykinis, neuropeptide Y, and b-adrenergic receptors. How they function and their crosstalks with the immune system in the progression, especially the metastasis of gastrointestinal cancer, will be described. Finally, we will summarize the clinical implications in the treatment of gastrointestinal cancer.

Adrenergic signaling promotes angiogenesis through endothelial cell-tumor cell crosstalk

Angiogenesis is an important factor in invasive tumor growth, progression, and metastasis. Multiple proangiogenic mechanisms are involved in tumor angiogenesis. In this study, we showed that the neurotransmitter norepinephrine upregulated VEGF (VEGFA) expression in breast cancer cells and that the culture supernatant from norepinephrine-treated breast cancer cells promoted the formation of the capillary-like network of endothelial cells. However, the effects of norepinephrine were further enhanced when the endothelial cells were cocultured with breast cancer cells, indicating a critical role of tumor cell-endothelial cell contacts in norepinephrine-induced tumor angiogenesis. Interestingly, norepinephrine dramatically induced the activation of the Notch pathway, which is a cell-contact-mediated intercellular signaling pathway and tightly linked to tumor cell-stromal cell interaction and angiogenesis, in the endothelial cells that had been cocultured with breast cancer cells. Furthermore, the expression of the Notch ligand Jagged 1 was significantly upregulated by norepinephrine at both mRNA and protein levels in breast cancer cells. Inhibitors of β2-adrenergic receptor (β2-AR), protein kinase A (PKA), and mTOR could reverse norepinephrine-induced Jagged 1 upregulation, indicating that the β2-AR-PKA-mTOR pathway participates in this process. Knockdown of Jagged 1 expression in breast cancer cells not only repressed norepinephrine-induced activation of the Notch pathway in cocultured endothelial cells but also evidently impaired the effects of norepinephrine on capillary-like sprout formation. These data demonstrate that tumor angiogenesis mediated by the Jagged 1/Notch intercellular signaling is governed by the norepinephrine-activated β2-AR-PKA-mTOR pathway.

β-Adrenergic system, a backstage manipulator regulating tumour progression and drug target in cancer therapy

β-Adrenoceptors are broadly distributed in various tissues of the body. Stress hormones regulate a panel of important physiological functions and disease states including cancer. Nicotine and its derivatives could stimulate the release of stress hormones from cancer cells, leading to the promotion of cancer development. β-Blockers have been widely used to control hypertension for decades. Recently, these agents could have significant implications in cancer therapy through blockade of adrenoceptors in tumour tissues. In this review, we summarize recent advancements about the influence of stress hormones, nicotine and β-adrenoceptors on cancer cell proliferation, apoptosis, invasion and metastasis, and also tumour vasculature normalization. Relevant signal pathways and potential value of β-blockers in the treatment of cancer are also discussed in this review.