Sympathetic Signaling Reactivates Quiescent Disseminated Prostate Cancer Cells in the Bone Marrow

β‑adrenergic receptor activation promotes the proliferation of HepG2 cells via the ERK1/2/CREB pathways

Primary liver cancer is one of the most frequently diagnosed malignant tumors seen in clinics, and typically exhibits aggressive invasive behaviors, a poor prognosis, and is associated with high mortality rates. Long-term stress exposure causes norepinephrine (NE) release and activates the β-Adrenergic receptor (β-AR), which in turn exacerbates the occurrence and development of different types of cancers; however, the molecular mechanisms of β-AR in liver cancer are not fully understood. In the present study, reverse transcription (RT)-PCR and RT-quantitative PCR showed that β-AR expression was upregulated in human liver cancer cells (HepG2) compared with normal liver cells (LO2). Moreover, NE treatment promoted the growth of HepG2 cells, which could be blocked by propranolol, a β-AR antagonist. Notably, NE had no significant effect on the migration and epithelial-mesenchymal transition in HepG2 cells. Further experiments revealed that NE increased the phosphorylation levels of the extracellular signal-regulated kinase 1/2 (ERK1/2) and cyclic adenosine monophosphate response element-binding protein (CREB), while inhibition of ERK1/2 and CREB activation significantly blocked NE-induced cell proliferation. In summary, the findings of the present study suggested that β-adrenergic receptor activation promoted the proliferation of HepG2 cells through ERK1/2/CREB signaling pathways.

Inhibition of Mertk Signaling Enhances Bone Healing after Tooth Extraction

Regeneration of alveolar bone is an essential step in restoring healthy function following tooth extraction. Growth of new bone in the healing extraction socket can be variable and often unpredictable when systemic comorbidities are present, leading to the need for additional therapeutic targets to accelerate the regenerative process. One such target is the TAM family (Tyro3, Axl, Mertk) of receptor tyrosine kinases. These proteins have been shown to help resolve inflammation and maintain bone homeostasis and thus may have therapeutic benefits in bone regeneration following extraction. Treatment of mice with a pan-TAM inhibitor (RXDX-106) led to accelerated alveolar bone fill following first molar extraction in a mouse model without changing immune infiltrate. Treatment of human alveolar bone mesenchymal stem cells with RXDX-106 upregulated Wnt signaling and primed the cells for osteogenic differentiation. Differentiation of human alveolar bone mesenchymal stem cells with osteogenic media and TAM-targeted inhibitor RXDX-106 (pan-TAM), ASP-2215 (Axl specific), or MRX-2843 (Mertk specific) showed enhanced mineralization with pan-TAM or Mertk-specific inhibitors and no change with Axl-specific inhibitor. First molar extractions in Mertk-/- mice had increased alveolar bone regeneration in the extraction socket relative to wild type controls 7 d postextraction. Flow cytometry of 7-d extraction sockets showed no difference in immune cell numbers between Mertk-/- and wild type mice. RNAseq of day 7 extraction sockets showed increased innate immune-related pathways and genes associated with bone differentiation in Mertk-/- mice. Together, these results indicate that TAM receptor signaling, specifically through Mertk, can be targeted to enhance bone regeneration after injury.

Awakening of Dormant Breast Cancer Cells in the Bone Marrow

Up to 40% of patients with breast cancer (BC) have metastatic cells in the bone marrow (BM) at the initial diagnosis of localized disease. Despite definitive systemic adjuvant therapy, these cells survive in the BM microenvironment, enter a dormant state and recur stochastically for more than 20 years. Once they begin to proliferate, recurrent macrometastases are not curable, and patients generally succumb to their disease. Many potential mechanisms for initiating recurrence have been proposed, but no definitive predictive data have been generated. This manuscript reviews the proposed mechanisms that maintain BC cell dormancy in the BM microenvironment and discusses the data supporting specific mechanisms for recurrence. It addresses the well-described mechanisms of secretory senescence, inflammation, aging, adipogenic BM conversion, autophagy, systemic effects of trauma and surgery, sympathetic signaling, transient angiogenic bursts, hypercoagulable states, osteoclast activation, and epigenetic modifications of dormant cells. This review addresses proposed approaches for either eliminating micrometastases or maintaining a dormant state.

The Secretome of Parental and Bone Metastatic Breast Cancer Elicits Distinct Effects in Human Osteoclast Activity after Activation of β2 Adrenergic Signaling

The sympathetic nervous system (SNS), particularly through the β2 adrenergic receptor (β2-AR), has been linked with breast cancer (BC) and the development of metastatic BC, specifically in the bone. Nevertheless, the potential clinical benefits of exploiting β2-AR antagonists as a treatment for BC and bone loss-associated symptoms remain controversial. In this work, we show that, when compared to control individuals, the epinephrine levels in a cohort of BC patients are augmented in both earlier and late stages of the disease. Furthermore, through a combination of proteomic profiling and functional in vitro studies with human osteoclasts and osteoblasts, we demonstrate that paracrine signaling from parental BC under β2-AR activation causes a robust decrease in human osteoclast differentiation and resorption activity, which is rescued in the presence of human osteoblasts. Conversely, metastatic bone tropic BC does not display this anti-osteoclastogenic effect. In conclusion, the observed changes in the proteomic profile of BC cells under β-AR activation that take place after metastatic dissemination, together with clinical data on epinephrine levels in BC patients, provided new insights on the sympathetic control of breast cancer and its implications on osteoclastic bone resorption.

Locally sourced: site-specific immune barriers to metastasis

Tumour cells migrate very early from primary sites to distant sites, and yet metastases often take years to manifest themselves clinically or never even surface within a patient's lifetime. This pause in cancer progression emphasizes the existence of barriers that constrain the growth of disseminated tumour cells (DTCs) at distant sites. Although the nature of these barriers to metastasis might include DTC-intrinsic traits, recent studies have established that the local microenvironment also controls the formation of metastases. In this Perspective, I discuss how site-specific differences of the immune system might be a major selective growth restraint on DTCs, and argue that harnessing tissue immunity will be essential for the next stage in immunotherapy development that reliably prevents the establishment of metastases.

ADRB2 Regulates the Proliferation and Metastasis of Gastrointestinal Stromal Tumor Cells by Enhancing the ETV1-c-KIT Signaling

Background

Gastrointestinal stromal tumor (GIST) originates from a pacemaker cell, the Cajal cell. However, little is known about the cancer neuroscience in GIST. In this study, we aimed to elucidate the clinical and biological roles of adrenoceptor beta 2 (ADRB2) in GIST.

Methods

Immunohistochemistry was used to evaluate the expression of ADRB2 in GIST tissues. The biological effects of ADRB2 on GIST cell proliferation, migration, invasion, and apoptosis were explored using Cell Counting Kit -8, plate colony formation assay, transwell invasion assay, and flow cytometry. We also explored the growth and metastasis of xenograft tumors in nude mice. Western blotting was used to quantify protein expression and phosphorylation.

Results

ADRB2 is generally highly expressed in GIST. High ADRB2 expression was significantly associated with risk level, tumor size, mitotic count, and metastasis. Overexpression of ADRB2 promoted GIST cell proliferation, migration, invasion, and apoptosis, while silencing ADRB2 expression showed the opposite effects. Furthermore, we found that silencing endogenous ADRB2 inhibited GIST progression and metastasis in nude mice. ADRB2-induced ETV1 upregulation enhanced the activation of c-KIT.

Conclusion

ADRB2 plays an important role in the proliferation and metastasis of GIST and is expected to be a potential target for the treatment of GIST.

Inhibition of signaling downstream of beta-2 adrenoceptor by propranolol in prostate cancer cells

BACKGROUND

There is accumulating evidence that propranolol, an antagonist of beta-1 and beta-2 adrenoreceptors, extends survival of patients with prostate cancer; yet it is not known whether propranolol inhibits beta-adrenergic signaling in prostate cancer cells, or systemic effects of propranolol play the leading role in slowing down cancer progression. Recently initiated clinical studies offer a possibility to test whether administration of propranolol inhibits signaling pathways in prostate tumors, however, there is limited information on the dynamics of signaling pathways activated downstream of beta-2 adrenoreceptors in prostate cancer cells and on the inactivation of these pathways upon propranolol administration.

METHODS

Western blot analysis was used to test the effects of epinephrine and propranolol on activation of protein kinase (PKA) signaling in mouse prostates and PKA, extracellular signal-regulated kinase (ERK), and protein kinase B/AKT (AKT) signaling in prostate cancer cell lines.

RESULTS

In prostate cancer cell lines epinephrine induced robust phosphorylation of PKA substrates pS133CREB and pS157VASP that was evident 2 min after treatments and lasted for 3-6 h. Epinephrine induced phosphorylation of AKT in PTEN-positive 22Rv1 cells, whereas changes of constitutive AKT phosphorylation were minimal in PTEN-negative PC3, C42, and LNCaP cells. A modest short-term increase of pERK in response to epinephrine was observed in all tested cell lines. Incubation of prostate cancer cells with 10-fold molar excess of propranolol for 30 min inhibited all downstream pathways activated by epinephrine. Subjecting mice to immobilization stress induced phosphorylation of S133CREB, whereas injection of propranolol at 1.5 mg/kg prevented the stress-induced phosphorylation.

CONCLUSIONS

The analysis of pS133CREB and pS157VASP allows measuring activation of PKA signaling downstream of beta-2 adrenoreceptors. Presented results on the ratio of propranolol/epinephrine and the time needed to inhibit signaling downstream of beta-2 adrenoreceptors will help to design clinical studies that examine the effects of propranolol on prostate tumors.

An Overview of the Molecular Cues and Their Intracellular Signaling Shared by Cancer and the Nervous System: From Neurotransmitters to Synaptic Proteins, Anatomy of an All-Inclusive Cooperation

We propose an overview of the molecular cues and their intracellular signaling involved in the crosstalk between cancer and the nervous system. While "cancer neuroscience" as a field is still in its infancy, the relation between cancer and the nervous system has been known for a long time, and a huge body of experimental data provides evidence that tumor-nervous system connections are widespread. They encompass different mechanisms at different tumor progression steps, are multifaceted, and display some intriguing analogies with the nervous system's physiological processes. Overall, we can say that many of the paradigmatic "hallmarks of cancer" depicted by Weinberg and Hanahan are affected by the nervous system in a variety of manners.

Osteoblasts and osteoclasts: an important switch of tumour cell dormancy during bone metastasis

Bone metastasis occurs when tumour cells dissociate from primary tumours, enter the circulation (circulating tumour cells, CTCs), and colonize sites in bone (disseminated tumour cells, DTCs). The bone marrow seems to be a particularly dormancy-inducing environment for DTCs, yet the mechanisms of dormancy initiation, reactivation, and interaction within the bone marrow have to be elucidated. Intriguingly, some evidence has suggested that dormancy is a reversible state that is switched 'on' or 'off' depending on the presence of various bone marrow resident cells, particularly osteoclasts and osteoblasts. It has become clear that these two cells contribute to regulating dormant tumour cells in bone both directly (interaction) and indirectly (secreted factors). The involved mechanisms include TGFβ signalling, the Wnt signalling axis, the Notch2 pathway, etc. There is no detailed review that specifically focuses on ascertaining the dynamic interactions between tumour cell dormancy and bone remodelling. In addition, we highlighted the roles of inflammatory cytokines during this 'cell-to-cell' communication. We also discussed the potential clinical relevance of remodelling the bone marrow niche in controlling dormant tumour cells. Understanding the unique role of osteoclasts and osteoblasts in regulating tumour dormancy in bone marrow will provide new insight into preventing and treating tumour bone metastasis.

Stress-induced epinephrine promotes epithelial-to-mesenchymal transition and stemness of CRC through the CEBPB/TRIM2/P53 axis

Background

Previous studies have indicated that chronic emotional stressors likely participate in the occurrence of cancers. However, direct evidence connecting stress and colorectal cancer development remains almost completely unexplored.

Methods

Chronic stress mouse model was used to investigate the influence of stress on tumorigenesis. Several major agonists and antagonists of adrenergic receptors were applied to investigate the effects of β-adrenergic signaling on the development of CRC. Chromatin immunoprecipitation assays (CHIP) were used to investigate the binding of p53 and CEBPB to TRIM2 promoter. Mammosphere cultures, Cell Counting Kit-8 (CCK-8) assay, colony-formation assay, scratch wound healing assays, qPCR, immunofluorescence, coimmunoprecipitation and western blotting were used to explore the effect of stress-induced epinephrine on the CEBPB/TRIM2/P53 axis and the progress of CRC cells.

Results

In this study, we found that stress-induced epinephrine (EPI) promotes the proliferation, metastasis and CSC generation of CRC primarily through the β2-adrenergic receptor. Furthermore, our studies also confirmed that chronic stress decreased the stability of p53 protein by promoting p53 ubiquitination. Results of transcriptome sequencing indicated that TRIM2 was overexpressed in cells treated with EPI. Further studies indicated that TRIM2 could regulate the stability of p53 protein by promoting p53 ubiquitination. Finally, we further proved that CEBPB was regulated by EPI and acts as the upstream transcription factor of TRIM2.

Conclusions

Our studies proved that stress-induced EPI promotes the development and stemness of CRC through the CEBPB/TRIM2/P53 axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03467-8.

Patterns of indolence in prostate cancer (Review)

Although prostate cancer is a major cause of cancer-related mortality worldwide, most patients will have a relatively indolent clinical course. Contrary to most other types of cancer, even the diagnosis of locally advanced or metastatic disease is not always lethal. The present review aimed to summarize what is known regarding the underlying mechanisms related to the indolent course of subsets of prostate cancer, at various stages. The data suggested that no specific gene alteration by itself was responsible for carcinogenesis or disease aggressiveness. However, pathway analysis identified genetic aberrations in multiple critical pathways that tend to accumulate over the course of the disease. The progression from indolence into aggressive disease is associated with a complex interplay in which genetic and epigenetic factors are involved. The effect of the immune tumor microenvironment is also very important. Emerging evidence has suggested that the upregulation of pathways related to cellular aging and senescence can identify patients with indolent disease. In addition, a number of tumors enter a long-lasting quiescent state. Further research will determine whether halting tumor evolution is a feasible option, and whether the life of patients can be markedly prolonged by inducing tumor senescence or long-term dormancy.

Acquired and congenital spinal cord injury is associated with lower likelihood of PSA screening

PURPOSE

Studies have demonstrated lower prevalence of prostate cancer among patients with spinal cord injury but more advanced stage at diagnosis. However, there is a lack of literature on prostate cancer screening among these patients. We sought to evaluate prostate cancer screening occurrence in patients with spinal cord injury at our institution compared to a matched, unaffected population.

METHODS

We conducted a retrospective review of patients with the criteria: male, age 50-70, and diagnosis of cerebral palsy, spina bifida, or quadriplegia. A control cohort was matched by age, race, insurance, and co-morbidities. PSA screening, PSA value, prostate MRI, prostate biopsy, and biopsy outcome were compared. Multivariate logistic regression analysis was performed to determine the association between patient variables and PSA screening.

RESULTS

The study cohort and control cohort included 2180 patients each. Patients with spinal cord injury had significantly lower rates of PSA screening (15% vs 24%, p < 0.00001), MRI (0.1% vs 0.6%, p = 0.02), and biopsy (0.6% vs 1.3%, p = 0.01) compared to control. Spinal cord injury was associated with a lower likelihood of PSA screening (OR = 0.56, CI = 0.48 - 0.65, p < 0.00001). There were no significant differences in PSA value and biopsy outcomes.

CONCLUSION

Patients with spinal cord injury had a lower likelihood of PSA screening compared to a matched control population. Since PSA screening is a shared-decision making process, providers should consider the increasing life expectancy of patients with spinal cord injury and risks of under-testing for prostate cancer.

Current challenges in metastasis research and future innovation for clinical translation

While immense strides have been made in understanding tumor biology and in developing effective treatments that have substantially improved the prognosis of cancer patients, metastasis remains the major cause of cancer-related death. Improvements in the detection and treatment of primary tumors are contributing to a growing, detailed understanding of the dynamics of metastatic progression. Yet challenges remain in detecting metastatic dissemination prior to the establishment of overt metastases and in predicting which patients are at the highest risk of developing metastatic disease. Further improvements in understanding the mechanisms governing metastasis have great potential to inform the adaptation of existing therapies and the development of novel approaches to more effectively control metastatic disease. This article presents a forward-looking perspective on the challenges that remain in the treatment of metastasis, and the exciting emerging approaches that promise to transform the treatment of metastasis in cancer patients.

Chronic Stress Effects on Tumor: Pathway and Mechanism

Chronic stress is an emotional experience that occurs when people encounter something they cannot adapt to. Repeated chronic stress increases the risk of a variety of diseases, such as cardiovascular disease, depression, endocrine disease, inflammation and cancer. A growing body of research has shown that there is a link between chronic stress and tumor occurrence in both animal studies and clinical studies. Chronic stress activates the neuroendocrine system (hypothalamic-pituitary-adrenal axis) and sympathetic nervous system. Stress hormones promote the occurrence and development of tumors through various mechanisms. In addition, chronic stress also affects the immune function of the body, leading to the decline of immune monitoring ability and promote the occurrence of tumors. The mechanisms of chronic stress leading to tumor include inflammation, autophagy and epigenetics. These factors increase the proliferation and invasion capacity of tumor cells and alter the tumor microenvironment. Antagonists targeting adrenergic receptors have played a beneficial role in improving antitumor activity, as well as chemotherapy resistance and radiation resistance. Here, we review how these mechanisms contribute to tumor initiation and progression, and discuss whether these molecular mechanisms might be an ideal target to treat tumor.

Association of β-Blocker Use at Time of Radical Prostatectomy With Rate of Treatment for Prostate Cancer Recurrence

IMPORTANCE

The perioperative period has gained attention as a window of opportunity to prevent cancer recurrence. Evidence in support of a role for nonselective β-blockers (nsBBs) in cancer treatment is increasing, and counteracting cancer recurrence associated with perioperative stress and catecholamine is one of the suggested mechanisms of action.

OBJECTIVE

To explore whether use of nsBBs at the time of radical prostatectomy is associated with a lower rate of treatment for prostate cancer recurrence.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study analyzed prospectively collected data from the Cancer Registry of Norway, Norwegian Patient Registry, Norwegian Prescription Database, and Norwegian Cause of Death Registry. Of 12 298 eligible patients, this study included 11 117 treatment-naive patients with prostate cancer (ie, no prior hormonal therapy, radiotherapy, or chemotherapy) who underwent radical prostatectomy in Norway from January 1, 2008, to December 31, 2015, with a minimum progression-free follow-up of 6 months. Data analysis was performed from April 20, 2020, to April 30, 2021.

EXPOSURES

Use of nsBBs and selective β-blockers (sBBs) at time of radical prostatectomy.

MAIN OUTCOMES AND MEASURES

Treatment for cancer recurrence after radical prostatectomy (defined as initiation of hormonal therapy, radiotherapy, or chemotherapy) or, if no treatment was identified, cancer-specific mortality.

RESULTS

The study included 11 117 men with prostate cancer (median [IQR] age at radical prostatectomy, 64.8 [60.4-68.3] years). Of these, 1622 (14.6%) later received treatment for cancer recurrence during a median follow-up of 4.3 years (IQR, 2.4-6.3 years). Use of nsBBs at time of surgery among 209 patients was significantly associated with a lower risk of treatment for cancer recurrence (adjusted hazard ratio [aHR], 0.64; 95% CI, 0.42-0.96; P = .03). No such association was observed for use of sBBs (aHR, 0.96; 95% CI, 0.84-1.11; P = .62). Subanalyses with (1) relaxed inclusion criteria allowing for inclusion also of patients with early progression (within 6 months) and (2) only the healthiest patients (Eastern Cooperative Oncology Group performance status of 0) supported the main findings.

CONCLUSIONS AND RELEVANCE

In this cohort study, use of nsBB but not sBBs at the time of radical prostatectomy was associated with less treatment initiation for cancer recurrence. This finding, together with accumulated preclinical and clinical evidence, provides a foundation for initiation of an interventional study.

Prostate cancer dormancy and recurrence

Prostate cancer can progress rapidly after diagnosis, but can also become undetectable after curative intent radiation or surgery, only to recur years or decades later. This capacity to lie dormant and recur long after a patient was thought to be cured, is relatively unique to prostate cancer, with estrogen receptor positive breast cancer being the other common and well-studied example. Most investigators agree that the bone marrow is an important site for dormant tumor cells, given the frequency of bone metastases and that multiple studies have reported disseminated tumor cells in patients with localized disease. However, while more difficult to study, lymph nodes and the prostate bed are likely to be important reservoirs as well. Dormant tumor cells may be truly quiescent and in the G0 phase of the cell cycle, which is commonly called cellular dormancy. However, tumor growth may also be held in check through a balance of proliferation and cell death (tumor mass dormancy). For induction of cellular dormancy, prostate cancer cells respond to signals from their microenvironment, including TGF-β2, BMP-7, GAS6, and Wnt-5a, which result in signals transduced in part through p38 MAPK and pluripotency associated transcription factors including SOX2 and NANOG, which likely affect the epi-genome through histone modification. Clinical use of adjuvant radiation or androgen deprivation has been modestly successful to prevent recurrence. With the rapid pace of discovery in this field, systemic adjuvant therapy is likely to continue to improve in the future.

Thorny ground, rocky soil: Tissue-specific mechanisms of tumor dormancy and relapse

Disseminated tumor cells (DTCs) spread systemically yet distinct patterns of metastasis indicate a range of tissue susceptibility to metastatic colonization. Distinctions between permissive and suppressive tissues are still being elucidated at cellular and molecular levels. Although there is a growing appreciation for the role of the microenvironment in regulating metastatic success, we have a limited understanding of how diverse tissues regulate DTC dormancy, the state of reversible quiescence and subsequent awakening thought to contribute to delayed relapse. Several themes of microenvironmental regulation of dormancy are beginning to emerge, including vascular association, co-option of pre-existing niches, metabolic adaptation, and immune evasion, with tissue-specific nuances. Conversely, DTC awakening is often associated with injury or inflammation-induced activation of the stroma, promoting a proliferative environment with DTCs following suit. We review what is known about tissue-specific regulation of tumor dormancy on a tissue-by-tissue basis, profiling major metastatic organs including the bone, lung, brain, liver, and lymph node. An aerial view of the barriers to metastatic growth may reveal common targets and dependencies to inform the therapeutic prevention of relapse.

Stress and cancer: mechanisms, significance and future directions

The notion that stress and cancer are interlinked has dominated lay discourse for decades. More recent animal studies indicate that stress can substantially facilitate cancer progression through modulating most hallmarks of cancer, and molecular and systemic mechanisms mediating these effects have been elucidated. However, available clinical evidence for such deleterious effects is inconsistent, as epidemiological and stress-reducing clinical interventions have yielded mixed effects on cancer mortality. In this Review, we describe and discuss specific mediating mechanisms identified by preclinical research, and parallel clinical findings. We explain the discrepancy between preclinical and clinical outcomes, through pointing to experimental strengths leveraged by animal studies and through discussing methodological and conceptual obstacles that prevent clinical studies from reflecting the impacts of stress. We suggest approaches to circumvent such obstacles, based on targeting critical phases of cancer progression that are more likely to be stress-sensitive; pharmacologically limiting adrenergic-inflammatory responses triggered by medical procedures; and focusing on more vulnerable populations, employing personalized pharmacological and psychosocial approaches. Recent clinical trials support our hypothesis that psychological and/or pharmacological inhibition of excess adrenergic and/or inflammatory stress signalling, especially alongside cancer treatments, could save lives.

The Relationship Between Mesenchymal Stem Cells and Tumor Dormancy

Tumor dormancy, a state of tumor, is clinically undetectable and the outgrowth of dormant tumor cells into overt metastases is responsible for cancer-associated deaths. However, the dormancy-related molecular mechanism has not been clearly described. Some researchers have proposed that cancer stem cells (CSCs) and disseminated tumor cells (DTCs) can be seen as progenitor cells of tumor dormancy, both of which can remain dormant in a non-permissive soil/niche. Nowadays, research interest in the cancer biology field is skyrocketing as mesenchymal stem cells (MSCs) are capable of regulating tumor dormancy, which will provide a unique therapeutic window to cure cancer. Although the influence of MSCs on tumor dormancy has been investigated in previous studies, there is no thorough review on the relationship between MSCs and tumor dormancy. In this paper, the root of tumor dormancy is analyzed and dormancy-related molecular mechanisms are summarized. With an emphasis on the role of the MSCs during tumor dormancy, new therapeutic strategies to prevent metastatic disease are proposed, whose clinical application potentials are discussed, and some challenges and prospects of the studies of tumor dormancy are also described.

Psychosocial Stress and Age Influence Depression and Anxiety-Related Behavior, Drive Tumor Inflammatory Cytokines and Accelerate Prostate Cancer Growth in Mice

Prostate cancer (PCa) prevalence is higher in older men and poorer coping with psychosocial stressors effect prognosis. Yet, interactions between age, stress and PCa progression are underexplored. Therefore, we characterized the effects of age and isolation combined with restraint (2 h/day) for 14 days post-tumor inoculation on behavior, tumor growth and host defense in the immunocompetent, orthotopic RM-9 murine PCa model. All mice were tumor inoculated. Isolation/restraint increased sympathetic and hypothalamic-pituitary-adrenal cortical activation, based on elevated serum 3-methoxy-4-hydroxyphenylglycol/norepinephrine ratios and corticosterone levels, respectively. Elevated zero maze testing revealed age-related differences in naïve C57Bl/6 mice, and increased anxiety-like behavior in tumor-bearing mice. In open field testing, old stressed mice were less active throughout the 30-min test than young non-stressed and stressed, and old non-stressed mice, suggesting greater anxiety in old stressed mice. Old (18 month) mice demonstrated more depression-like behavior than young mice with tail suspension testing, without effects of isolation/restraint stress. Old mice developed larger tumors, despite similar tumor expression of tumor vascular endothelial growth factor or transforming growth factor-beta1 across age. Tumor chemokine/cytokine expression, commonly prognostic for poorer outcomes, were uniquely age- and stress-dependent, underscoring the need for PCa research in old animals. Macrophages predominated in RM-9 tumors. Macrophages, and CD4⁺ and CD4⁺FoxP3⁺ T-cell tumor infiltration were greater in young mice than in old mice. Stress increased macrophage infiltration in old mice. Conversely, stress reduced intratumoral CD4⁺ and CD4⁺FoxP3⁺ T-cell numbers in young mice. CD8⁺ T-cell infiltration was similar across treatment groups. Our findings support that age- and psychological stress interacts to affect PCa outcomes by interfering with neural-immune mechanisms and affecting behavioral responses.

Osmotic pressure modulates single cell cycle dynamics inducing reversible growth arrest and reactivation of human metastatic cells

Biophysical cues such as osmotic pressure modulate proliferation and growth arrest of bacteria, yeast cells and seeds. In tissues, osmotic regulation takes place through blood and lymphatic capillaries and, at a single cell level, water and osmoregulation play a critical role. However, the effect of osmotic pressure on single cell cycle dynamics remains poorly understood. Here, we investigate the effect of osmotic pressure on single cell cycle dynamics, nuclear growth, proliferation, migration and protein expression, by quantitative time-lapse imaging of single cells genetically modified with fluorescent ubiquitination-based cell cycle indicator 2 (FUCCI2). Single cell data reveals that under hyperosmotic stress, distinct cell subpopulations emerge with impaired nuclear growth, delayed or growth arrested cell cycle and reduced migration. This state is reversible for mild hyperosmotic stress, where cells return to regular cell cycle dynamics, proliferation and migration. Thus, osmotic pressure can modulate the reversible growth arrest and reactivation of human metastatic cells.

Prostate Cancer Dormancy and Reactivation in Bone Marrow

Prostate cancer has a variable clinical course, ranging from curable local disease to lethal metastatic spread. Eradicating metastatic cells is a unique challenge that is rarely met with the available therapies. Thus, targeting prostate cancer cells in earlier disease states is a crucial window of opportunity. Interestingly, cancer cells migrate from their primary site during pre-cancerous and malignant phases to seed secondary organs. These cells, known as disseminated cancer cells (DCCs), may remain dormant for months or decades before activating to form metastases. Bone marrow, a dormancy-permissive site, is the major organ for housed DCCs and eventual metastases in prostate cancer. The dynamic interplay between DCCs and the primary tumor microenvironment (TME), as well as that between DCCs and the secondary organ niche, controls the conversion between states of dormancy and activation. Here, we discuss recent discoveries that have improved our understanding of dormancy signaling and the role of the TME in modulating the epigenetic reprogramming of DCCs. We offer potential strategies to target DCCs in prostate cancer.

Slow-cycling (dormant) cancer cells in therapy resistance, cancer relapse and metastasis

It is increasingly appreciated that cancer cell heterogeneity and plasticity constitute major barriers to effective clinical treatments and long-term therapeutic efficacy. Research in the past two decades suggest that virtually all treatment-naive human cancers harbor subsets of cancer cells that possess many of the cardinal features of normal stem cells. Such stem-like cancer cells, operationally defined as cancer stem cells (CSCs), are frequently quiescent and dynamically change and evolve during tumor progression and therapeutic interventions. Intrinsic tumor cell heterogeneity is reflected in a different aspect in that tumors also harbor a population of slow-cycling cells (SCCs) that are not in the proliferative cell cycle and thus are intrinsically refractory to anti-mitotic drugs. In this Perspective, we focus our discussions on SCCs in cancer and on various methodologies that can be employed to enrich and purify SCCs, compare the similarities and differences between SCCs, CSCs and cancer cells undergoing EMT, and present evidence for the involvement of SCCs in surviving anti-neoplastic treatments, mediating tumor relapse, maintaining tumor dormancy and mediating metastatic dissemination. Our discussions make it clear that an in-depth understanding of the biological properties of SCCs in cancer will be instrumental to developing new therapeutic strategies to prevent tumor relapse and distant metastasis.

Crosstalk between Bone and Nerves within Bone

For the past two decades, the function of intrabony nerves on bone has been a subject of intense research, while the function of bone on intrabony nerves is still hidden in the corner. In the present review, the possible crosstalk between bone and intrabony peripheral nerves will be comprehensively analyzed. Peripheral nerves participate in bone development and repair via a host of signals generated through the secretion of neurotransmitters, neuropeptides, axon guidance factors and neurotrophins, with additional contribution from nerve-resident cells. In return, bone contributes to this microenvironmental rendezvous by housing the nerves within its internal milieu to provide mechanical support and a protective shelf. A large ensemble of chemical, mechanical, and electrical cues works in harmony with bone marrow stromal cells in the regulation of intrabony nerves. The crosstalk between bone and nerves is not limited to the physiological state, but also involved in various bone diseases including osteoporosis, osteoarthritis, heterotopic ossification, psychological stress-related bone abnormalities, and bone related tumors. This crosstalk may be harnessed in the design of tissue engineering scaffolds for repair of bone defects or be targeted for treatment of diseases related to bone and peripheral nerves.

Targeting Intercellular Communication in the Bone Microenvironment to Prevent Disseminated Tumor Cell Escape from Dormancy and Bone Metastatic Tumor Growth

Metastasis to the bone is a common feature of many cancers including those of the breast, prostate, lung, thyroid and kidney. Once tumors metastasize to the bone, they are essentially incurable. Bone metastasis is a complex process involving not only intravasation of tumor cells from the primary tumor into circulation, but extravasation from circulation into the bone where they meet an environment that is generally suppressive of their growth. The bone microenvironment can inhibit the growth of disseminated tumor cells (DTC) by inducing dormancy of the DTC directly and later on following formation of a micrometastatic tumour mass by inhibiting metastatic processes including angiogenesis, bone remodeling and immunosuppressive cell functions. In this review we will highlight some of the mechanisms mediating DTC dormancy and the complex relationships which occur between tumor cells and bone resident cells in the bone metastatic microenvironment. These inter-cellular interactions may be important targets to consider for development of novel effective therapies for the prevention or treatment of bone metastases.

Metastatic Spread in Prostate Cancer Patients Influencing Radiotherapy Response

Radiotherapy and surgery are curative treatment options for localized prostate cancer (PCa) with a 5-year survival rate of nearly 100%. Once PCa cells spread into distant organs, such as bone, the overall survival rate of patients drops dramatically. The metastatic cascade and organotropism of PCa cells are regulated by different cellular subtypes, organ microenvironment, and their interactions. This cross-talk leads to pre-metastatic niche formation that releases chemo-attractive factors enforcing the formation of distant metastasis. Biological characteristics of PCa metastasis impacting on metastatic sites, burden, and latency is of clinical relevance. Therefore, the implementation of modern hybrid imaging technologies into clinical routine increased the sensitivity to detect metastases at earlier stages. This enlarged the number of PCa patients diagnosed with a limited number of metastases, summarized as oligometastatic disease. These patients can be treated with androgen deprivation in combination with local-ablative radiotherapy or radiopharmaceuticals directed to metastatic sites. Unfortunately, the number of patients with disease recurrence is high due to the enormous heterogeneity within the oligometastatic patient population and the lack of available biomarkers with predictive potential for metastasis-directed radiotherapy. Another, so far unmet clinical need is the diagnosis of minimal residual disease before onset of clinical manifestation and/or early relapse after initial therapy. Here, monitoring of circulating and disseminating tumor cells in PCa patients during the course of radiotherapy may give us novel insight into how metastatic spread is influenced by radiotherapy and vice versa. In summary, this review critically compares current clinical concepts for metastatic PCa patients and discuss the implementation of recent preclinical findings improving our understanding of metastatic dissemination and radiotherapy resistance into standard of care.

Sympathetic activity in breast cancer and metastasis: partners in crime

The vast majority of patients with advanced breast cancer present skeletal complications that severely compromise their quality of life. Breast cancer cells are characterized by a strong tropism to the bone niche. After engraftment and colonization of bone, breast cancer cells interact with native bone cells to hinder the normal bone remodeling process and establish an osteolytic "metastatic vicious cycle". The sympathetic nervous system has emerged in recent years as an important modulator of breast cancer progression and metastasis, potentiating and accelerating the onset of the vicious cycle and leading to extensive bone degradation. Furthermore, sympathetic neurotransmitters and their cognate receptors have been shown to promote several hallmarks of breast cancer, such as proliferation, angiogenesis, immune escape, and invasion of the extracellular matrix. In this review, we assembled the current knowledge concerning the complex interactions that take place in the tumor microenvironment, with a special emphasis on sympathetic modulation of breast cancer cells and stromal cells. Notably, the differential action of epinephrine and norepinephrine, through either α- or β-adrenergic receptors, on breast cancer progression prompts careful consideration when designing new therapeutic options. In addition, the contribution of sympathetic innervation to the formation of bone metastatic foci is highlighted. In particular, we address the remarkable ability of adrenergic signaling to condition the native bone remodeling process and modulate the bone vasculature, driving breast cancer cell engraftment in the bone niche. Finally, clinical perspectives and developments on the use of β-adrenergic receptor inhibitors for breast cancer management and treatment are discussed.

Bone metastasis: mechanisms, therapies, and biomarkers

Skeletal metastases are frequent complications of many cancers, causing bone complications (fractures, bone pain, disability) that negatively affect the patient's quality of life. Here, we first discuss the burden of skeletal complications in cancer bone metastasis. We then describe the pathophysiology of bone metastasis. Bone metastasis is a multistage process: long before the development of clinically detectable metastases, circulating tumor cells settle and enter a dormant state in normal vascular and endosteal niches present in the bone marrow, which provide immediate attachment and shelter, and only become active years later as they proliferate and alter the functions of bone-resorbing (osteoclasts) and bone-forming (osteoblasts) cells, promoting skeletal destruction. The molecular mechanisms involved in mediating each of these steps are described, and we also explain how tumor cells interact with a myriad of interconnected cell populations in the bone marrow, including a rich vascular network, immune cells, adipocytes, and nerves. We discuss metabolic programs that tumor cells could engage with to specifically grow in bone. We also describe the progress and future directions of existing bone-targeted agents and report emerging therapies that have arisen from recent advances in our understanding of the pathophysiology of bone metastases. Finally, we discuss the value of bone turnover biomarkers in detection and monitoring of progression and therapeutic effects in patients with bone metastasis.

Cancer progression and the invisible phase of metastatic colonization

Metastatic dissemination occurs very early in the malignant progression of a cancer but the clinical manifestation of metastases often takes years. In recent decades, 5-year survival of patients with many solid cancers has increased due to earlier detection, local disease control and adjuvant therapies. As a consequence, we are confronted with an increase in late relapses as more antiproliferative cancer therapies prolong disease courses, raising questions about how cancer cells survive, evolve or stop growing and finally expand during periods of clinical latency. I argue here that the understanding of early metastasis formation, particularly of the currently invisible phase of metastatic colonization, will be essential for the next stage in adjuvant therapy development that reliably prevents metachronous metastasis.

Autonomic nervous system control of multiple myeloma

The autonomic nervous system (ANS), which consists of antagonistic sympathetic (adrenergic) and parasympathetic (cholinergic) arms, has emerged as an important regulator of neoplastic development, yet little is known about its role in multiple myeloma (MM). Clinical findings that anti-adrenergic β-blocker intake reduces risk of disease-specific death and overall mortality in patients with MM have indicated that adrenergic input may worsen myeloma outcome. However, preclinical studies using β-adrenergic receptor agonists or antagonists produced controversial results as to whether sympathetic pathways promote or inhibit myeloma. Retrospective outcome data demonstrating that high message levels of cholinergic receptor genes predict inferior survival in the Multiple Myeloma Research Foundation CoMMpass trial suggest that parasympathetic input may drive myeloma progression in a subset of patients. Here we review the ill-defined role of the ANS in MM, put myeloma in the context of other cancers, and discuss knowledge gaps that may afford exciting research opportunities going forward.

Adrenergic Blockade Promotes Maintenance of Dormancy in Prostate Cancer Through Upregulation of GAS6

Men diagnosed with localized prostate cancer can develop metastases many years after initial treatment, resulting in a poor prognosis. The purpose of this study was to investigate the mechanisms by which signaling through norepinephrine (NE) may incite relapse of quiescent prostate cancer. We used an unbiased bioinformatics pipeline to examine mechanisms for recurrence related to sympathetic signaling in the bone marrow. A transcription factor cell array identified ATF1, RAR, and E2F as key nodes in prostate cancer cells exiting quiescence through adrenergic signaling. Subsequent secretome analysis identified GAS6 as affecting activity of these three factors, leading to cell cycle reentry. GAS6 expression was downregulated in osteoblasts through activation of the cAMP pathway and was targeted in vitro and in vivo using pharmacological agents (propranolol and phentolamine). Propranolol increased expression of GAS6 by osteoblasts, and phentolamine significantly inhibited expression. Propranolol treatment was sufficient to both increase GAS6 expression in marrow osteoblasts as well as eliminate the effects of NE signaling on GAS6 expression. These results demonstrate a strong correlation between adrenergic signaling, GAS6 expression, and recurrence in prostate cancer, suggesting a novel therapeutic direction for patients at high risk of metastasis.

Tumour innervation and neurosignalling in prostate cancer

Prostate cancer progression has been shown to be dependent on the development of autonomic nerves into the tumour microenvironment. Sympathetic nerves activate adrenergic neurosignalling that is necessary in early stages of tumour progression and for initiating an angiogenic switch, whereas parasympathetic nerves activate cholinergic neurosignalling resulting in tumour dissemination and metastasis. The innervation of prostate cancer seems to be initiated by neurotrophic growth factors, such as the precursor to nerve growth factor secreted by tumour cells, and the contribution of brain-derived neural progenitor cells has also been reported. Current experimental, epidemiological and clinical evidence shows the stimulatory effect of tumour innervation and neurosignalling in prostate cancer. Using nerves and neurosignalling could have value in the management of prostate cancer by predicting aggressive disease, treating localized disease through denervation and relieving cancer-associated pain in bone metastases.

The Roles of Bone Marrow-Resident Cells as a Microenvironment for Bone Metastasis

It has been appreciated that the cross talk between bone metastatic cancer cells and bone marrow microenvironment influence one another to worsen bone metastatic disease progression. Bone marrow contains various cell types, including (1) cells of mesenchymal origin (e.g., osteoblasts, osteocytes, and adipocytes), (2) cells of hematopoietic origin (e.g., osteoclast and immune cells), and (3) others (e.g., endothelial cells and nerves). The recent studies have enabled us to discover many important cancer-derived factors responsible for the development of bone metastasis. However, many critical questions regarding the roles of bone microenvironment in bone metastatic progression remain elusive. To answer these questions, a deeper understanding of the cross talk between bone metastatic cancer and bone marrow microenvironment is clearly warranted.

Interactions between cancer cells and bone microenvironment promote bone metastasis in prostate cancer

Bone metastasis is the leading cause of death in prostate cancer patients, for which there is currently no effective treatment. Since the bone microenvironment plays an important role in this process, attentions have been directed to the interactions between cancer cells and the bone microenvironment, including osteoclasts, osteoblasts, and bone stromal cells. Here, we explained the mechanism of interactions between prostate cancer cells and metastasis-associated cells within the bone microenvironment and further discussed the recent advances in targeted therapy of prostate cancer bone metastasis. This review also summarized the effects of bone microenvironment on prostate cancer metastasis and the related mechanisms, and provides insights for future prostate cancer metastasis studies.

Chronic stress promotes gastric cancer progression and metastasis: an essential role for ADRB2

An increasing number of studies indicate that adrenergic signalling plays a fundamental role in chronic stress-induced tumour progression and metastasis. However, its function in gastric cancer (GC) and its potential mechanisms remain unknown. The expression levels of β-adrenergic receptor (ADRB) in GC cell lines were examined by using real-time polymerase chain reaction (RT-PCR) and western blotting. The effects of β2 adrenergic receptor (ADRB2) activation and blockade were investigated in vitro in GC cells by using proliferation, migration, invasion, cell cycle and apoptosis assays. Chronic restraint stress (CRS) increased the plasma levels of catecholamines and cortisol and also induced progression and metastasis of GC in vivo. Furthermore, immunohistochemical staining and a TUNEL assay were employed to observe the regulation of cell viability in vivo. The expression levels of ADRB2 in 100 human GC samples were measured by RT-PCR and immunohistochemistry. The stress hormones epinephrine and norepinephrine significantly accelerated GC cell proliferation, invasion and viability in culture, as well as tumour growth in vivo. These effects were reversed by the ADRB antagonists propranolol and ICI118,551 (an ADRB2-specific antagonist). Moreover, the selective ADRB1 antagonist atenolol had almost no effect on tumour cell proliferation and invasion in vitro and in vivo. ADRB2 antagonists suppressed proliferation, invasion and metastasis by inhibiting the ERK1/2-JNK-MAPK pathway and transcription factors, such as NF-κB, AP-1, CREB and STAT3. Analysis of xenograft models using GC cells revealed that ADRB2 antagonists significantly inhibited tumour growth and metastasis, and chronic stress antagonized these inhibitory effects. In addition, chronic stress increased the expression of VEGF, MMP-2, MMP-7 and MMP-9 in transplanted tumour tissue, and catecholamine hormones enhanced the expression of metastasis-related proteins. The expression of ADRB2 was upregulated in tumour tissues and positively correlated with tumour size, histological grade, lymph node metastasis and clinical stage in human GC samples. Stress hormone-induced activation of the ADRB2 signalling pathway plays a crucial role in GC progression and metastasis. These findings indicate that ADRB2 signalling regulates GC progression and suggest β2 blockade as a novel strategy to complement existing therapies for GC.

Selective β2-adrenoreceptor signaling regulates osteoclastogenesis via modulating RANKL production and neuropeptides expression in osteocytic MLO-Y4 cells

The β2-adrenergic receptor (β2-AR) signaling on bone cells is the major contributor in the effect of the sympathetic nervous system on bone turnover. However, it remains unclear whether receptor activator of nuclear factor κ-Β ligand (RANKL) modulation and neuropeptides expression in osteocytes are responsible for the mechanism. This study used β2-AR stimulation to investigate cell cycle and proliferation, the gene and protein expression of RANKL, and osteoprotegerin (OPG), as well as neuropeptides regulation in osteocytic MLO-Y4 cells. Clenbuterol (CLE; a β2-AR agonist) slightly promoted the growth of MLO-Y4 cells in a concentration-dependent effect but had no effect on the proliferation index. And the concentration of 10^-8  M showed a significant increase in the S-phase fraction on day 3 in comparison with the control. Additionally, CLE-promoted osteoclast formation and bone resorption in osteocytic MLO-Y4 cell-RAW264.7 cell cocultures. RANKL expression level and the ratio of RANKL to OPG in MLO-Y4 cells were enhanced in CLE treatment but were rescued by blocking β2-AR signaling. However, neuropeptide Y and α-calcitonin gene-related peptide, two neurogenic markers, were inhibited in CLE treatment of MLO-Y4 cells, which was reversed by a β2-AR blocker. The results indicate that osteocytic β2-AR plays an important role in the regulation of RANKL/OPG and neuropeptides expression, and β2-AR signaling in osteocytes can be used as a new valuable target for osteoclast-related pathologic disease.

Parallels between hematopoietic stem cell and prostate cancer disseminated tumor cell regulation

The bone marrow is the primary site of hematopoiesis and the home for hematopoietic stem cells (HSCs) in adult mammals. Prostate cancer commonly metastasizes to the bone and forms bone metastases in almost all patients who die of the disease. Prostate cancer bone metastases are thought to develop after rare bone marrow disseminated tumor cells (DTCs) escape a dormant state and reactivate. Prostate cancer DTCs and normal HSCs have been shown to compete for residence in the bone marrow and share many of same regulatory mechanisms for survival, proliferation and homing. In this review, we highlight these parallels in order to help our readers use the literature in HSC and DTC biology to inform their research and generate hypotheses in both fields.

Identification of Genes Regulating Breast Cancer Dormancy in 3D Bone Endosteal Niche Cultures

Tumor cell dormancy is a significant clinical problem in breast cancer. We used a three-dimensional (3D) in vitro model of the endosteal bone niche (EN), consisting of endothelial, bone marrow stromal cells, and fetal osteoblasts in a 3D collagen matrix (GELFOAM), to identify genes required for dormancy. Human triple-negative MDA-MB-231 breast cancer cells, but not the bone-tropic metastatic variant, BoM1833, established dormancy in 3D-EN cultures in a p38-MAPK-dependent manner, whereas both cell types proliferated on two-dimensional (2D) plastic or in 3D collagen alone. "Dormancy-reactivation suppressor genes" (DRSG) were identified using a genomic short hairpin RNA (shRNA) screen in MDA-MB-231 cells for gene knockdowns that induced proliferation in the 3D-EN. DRSG candidates enriched for genes controlling stem cell biology, neurogenesis, MYC targets, ribosomal structure, and translational control. Several potential DRSG were confirmed using independent shRNAs, including BHLHE41, HBP1, and WNT3. Overexpression of the WNT3/a antagonists secreted frizzled-related protein 2 or 4 (SFRP2/4) and induced MDA-MB-231 proliferation in the EN. In contrast, overexpression of SFRP3, known not to antagonize WNT3/a, did not induce proliferation. Decreased WNT3 or BHLHE41 expression was found in clinical breast cancer metastases compared with primary-site lesions, and the loss of WNT3 or BHLHE41 or gain of SFRP1, 2, and 4 in the context of TP53 loss/mutation correlated with decreased progression-free and overall survival. IMPLICATIONS: These data describe several novel, potentially targetable pathways controlling breast cancer dormancy in the EN.

Disseminated tumour cells in bone marrow are the source of cancer relapse after therapy

Accumulating evidence indicates that cancer cells spread much earlier than was previously believed. Recent technological advances have greatly improved the detection methods of circulating tumour cells (CTCs), suggesting that the dissemination of cancer cells into the circulation occurs randomly. Most CTCs die in circulation as a result of shear stress and/or anoikis. However, the persistence of disseminated tumour cells (DTCs) in the bone marrow is the result of interaction of DTCs with bone marrow microenvironment. DTCs in the bone marrow undergo successive clonal expansions and a parallel progression that leads to new variants. Compared to the CTCs, DTCs in the bone marrow have a unique signature, which displayed dormant, mesenchymal phenotype and osteoblast-like or osteoclast-like phenotype. The persistence of DTCs in the bone marrow is always related to minimal residual diseases (MRDs). This review outlines the difference between CTCs and DTCs in the bone marrow and describes how this difference affects the clinical values of CTCs and DTCs, such as metastasis and recurrence. We suggest that DTCs remaining in the bone marrow after therapy can be used as a superior marker in comparison with CTCs to define patients with an unfavourable prognosis and may therefore be a potential prognostic factor and therapeutic target for cancer therapy.

Depression-Induced Neuropeptide Y Secretion Promotes Prostate Cancer Growth by Recruiting Myeloid Cells

PURPOSE

Psychologic depression has been shown to dysregulate the immune system and promote tumor progression. The aim of this study is to investigate how psychologic depression alters the immune profiles in prostate cancer.

EXPERIMENTAL DESIGN

We used a murine model of depression in Myc-CaP tumor-bearing immunocompetent FVB mice and Hi-myc mice presenting with spontaneous prostate cancer. Transwell migration and coculture assays were used to evaluate myeloid cell trafficking and cytokine profile changes evoked by Myc-CaP cells that had been treated with norepinephrine (NE), a major elevated neurotransmitter in depression. Chemoattractant, which correlated with immune cell infiltration, was screened by RNA-seq. The chemoattractant and immune cell infiltration were further confirmed using clinical samples of patients with prostate cancer with a high score of psychologic depression.

RESULTS

Psychologic depression predominantly promoted tumor-associated macrophage (TAM) intratumor infiltrations, which resulted from spleen and circulating monocytic myeloid-derived suppressor cell mobilization. Neuropeptide Y (NPY) released from NE-treated Myc-CaP cells promotes macrophage trafficking and IL6 releasing, which activates STAT3 signaling pathway in prostate cancer cells. Clinical specimens from patients with prostate cancer with higher score of depression revealed higher CD68⁺ TAM infiltration and stronger NPY and IL6 expression.

CONCLUSIONS

Depression promotes myeloid cell infiltration and increases IL6 levels by a sympathetic-NPY signal. Sympathetic-NPY inhibition may be a promising strategy for patients with prostate cancer with high score of psychologic depression.See related commentary by Mohammadpour et al., p. 2363.

A direct effect of the autonomic nervous system on somatic stem cell proliferation?

Regulation of somatic stem cell proliferation is critical for the maintenance of tissue and organ function throughout the body. Modulators of this process include nutrients and peptides, but the role of an autonomic neural influence on stem cell proliferation has been neglected. This article describes the literature in support of autonomic nervous system (ANS) influence on somatic stem cells, with emphasis on intestinal epithelial stem cells (IESCs) as a representative somatic stem cell. Based on the current available data, models for the direct influence of both branches of the ANS (the sympathetic and parasympathetic nervous systems) on IESCs are outlined. Finally, the prospect of treatments derived from ANS influence on somatic stem cells is explored.

Interactions Between Disseminated Tumor Cells and Bone Marrow Stromal Cells Regulate Tumor Dormancy

PURPOSE OF REVIEW

To succinctly summarize recent findings concerning dormancy regulating interactions between bone marrow stromal cells and disseminated tumor cells.

RECENT FINDINGS

Recent studies have highlighted roles of the bone marrow microenviroment, including osteoblasts, mesenchymal stem cells (MSCs), and endothelial cells, in inducing or maintaining cancer cell dormancy. Key pathways of interest include: osteoblast-induced transforming growth factor (TGF)-β2 signaling, transfer of MSC-derived exosomes containing dormancy inducing microRNA, cancer cell cannibalism of MSCs, and endothelial cell secretion of thrombospondin 1 (TSP1). The bone marrow is a common site of metastatic disease recurrence following a period of cancer cell dormancy. Understanding why disseminated tumor cells enter into dormancy and later resume cell proliferation and growth is vital to developing effective therapeutics against these cells. The bone marrow stroma and the various pathways through which it participates in crosstalk with cancer cells are essential to furthering understanding of how dormancy is regulated.

Concise Review: Prostate Cancer Stem Cells: Current Understanding

Prostate cancer (PCa) is heterogeneous, harboring phenotypically diverse cancer cell types. PCa cell heterogeneity is caused by genomic instability that leads to the clonal competition and evolution of the cancer genome and by epigenetic mechanisms that result in subclonal cellular differentiation. The process of tumor cell differentiation is initiated from a population of prostate cancer stem cells (PCSCs) that possess many phenotypic and functional properties of normal stem cells. Since the initial reports on PCSCs in 2005, there has been much effort to elucidate their biological properties, including unique metabolic characteristics. In this Review, we discuss the current methods for PCSC enrichment and analysis, the hallmarks of PCSC metabolism, and the role of PCSCs in tumor progression. Stem Cells 2018;36:1457-1474.

The Sympathetic Nervous System Drives Tumor Angiogenesis

Neurobiology is increasingly contributing to cancer research. Recent work indicates that noradrenaline released by sympathetic adrenergic nerves in prostate cancer can stimulate β-adrenoceptors in endothelial cells. This leads to the alteration of endothelial cell metabolism toward the inhibition of oxidative phosphorylation and the induction of an angiogenic switch that fuels cancer progression. These findings suggest that the sympathetic nervous system is a higher-level control of tumor angiogenesis that could be targeted in clinical oncology.