Activin type IB receptor signaling in prostate cancer cells promotes lymph node metastasis in a xenograft model

Activin receptors in human cancer: Functions, mechanisms, and potential clinical applications

Activins are members of the transforming growth factor-β (TGF-β) superfamily and act as key regulators in various physiological processes, such as follicle and embryonic development, as well as in multiple human diseases, including cancer. They have been established to signal through three type I and two type II serine/threonine kinase receptors, which, upon ligand binding, form a final signal-transducing receptor complex that activates downstream signaling and governs gene expression. Recent research highlighted the dysregulation of the expression or activity of activin receptors in multiple human cancers and their critical involvement in cancer progression. Furthermore, expression levels of activin receptors have been associated with clinicopathological features and patient outcomes across different cancers. However, there is currently a paucity of comprehensive systematic reviews of activin receptors in cancer. Thus, this review aimed to consolidate existing knowledge concerning activin receptors, with a primary emphasis on their signaling cascade and emerging biological functions, regulatory mechanisms, and potential clinical applications in human cancers in order to provide novel perspectives on cancer prognosis and targeted therapy.

Appearance of tuft cells during prostate cancer progression

Tuft cells are chemosensory epithelial cells that increase in number following infection or injury to robustly activate the innate immune response to alleviate or promote disease. Recent studies of castration resistant prostate cancer and its subtype, neuroendocrine prostate cancer, revealed Pou2f3+ populations in mouse models. The transcription factor Pou2f3 is a master regulator of the tuft cell lineage. We show that tuft cells are upregulated early during prostate cancer development, and their numbers increase with progression. Cancer-associated tuft cells in the mouse prostate express DCLK1, COX1, COX2, while human tuft cells express COX1. Mouse and human tuft cells exhibit strong activation of signaling pathways including EGFR and SRC-family kinases. While DCLK1 is a mouse tuft cell marker, it is not present in human prostate tuft cells. Tuft cells that appear in mouse models of prostate cancer display genotype-specific tuft cell gene expression signatures. Using bioinformatic analysis tools and publicly available datasets, we characterized prostate tuft cells in aggressive disease and highlighted differences between tuft cell populations. Our findings indicate that tuft cells contribute to the prostate cancer microenvironment and may promote development of more advanced disease. Further research is needed to understand contributions of tuft cells to prostate cancer progression.

Bone morphogenetic proteins, activins, and growth and differentiation factors in tumor immunology and immunotherapy resistance

The TGF-β superfamily is a group of secreted polypeptides with key roles in exerting and regulating a variety of physiologic effects, especially those related to cell signaling, growth, development, and differentiation. Although its central member, TGF-β, has been extensively reviewed, other members of the family-namely bone morphogenetic proteins (BMPs), activins, and growth and differentiation factors (GDFs)-have not been as thoroughly investigated. Moreover, although the specific roles of TGF-β signaling in cancer immunology and immunotherapy resistance have been extensively reported, little is known of the roles of BMPs, activins, and GDFs in these domains. This review focuses on how these superfamily members influence key immune cells in cancer progression and resistance to treatment.

Mesenchymal Stromal Cells (MSCs): An Ally of B-Cell Acute Lymphoblastic Leukemia (B-ALL) Cells in Disease Maintenance and Progression within the Bone Marrow Hematopoietic Niche

Simple Summary

B-cell acute lymphoblastic leukemia (B-ALL) is the most common pediatric cancer. Even though the cure rate actually exceeds 85%, the prognosis of relapsed/refractory patients is dismal. Recent literature data indicate that the bone marrow (BM) microenvironment could play a crucial role in the onset, maintenance and progression of the disease. In particular, mesenchymal stromal cells (MSCs), which are key components of the BM niche, actively crosstalk with leukemic cells providing crucial signals for their survival and resistance to therapy. We hereby review the main mechanisms exploited by MSCs to nurture and protect B-ALL cells that could become appealing targets for innovative microenvironment remodeling therapies to be coupled with classical leukemia-directed strategies.

Abstract

Mesenchymal stromal cells (MSCs) are structural components of the bone marrow (BM) niche, where they functionally interact with hematopoietic stem cells and more differentiated progenitors, contributing to hematopoiesis regulation. A growing body of evidence is nowadays pointing to a further crucial contribution of MSCs to malignant hematopoiesis. In the context of B-cell acute lymphoblastic leukemia (B-ALL), MSCs can play a pivotal role in the definition of a leukemia-supportive microenvironment, impacting on disease pathogenesis at different steps including onset, maintenance and progression. B-ALL cells hijack the BM microenvironment, including MSCs residing in the BM niche, which in turn shelter leukemic cells and protect them from chemotherapeutic agents through different mechanisms. Evidence is now arising that altered MSCs can become precious allies to leukemic cells by providing nutrients, cytokines, pro-survivals signals and exchanging organelles, as hereafter reviewed. The study of the mechanisms exploited by MSCs to nurture and protect B-ALL blasts can be instrumental in finding new druggable candidates to target the leukemic BM microenvironment. Some of these microenvironment-targeting strategies are already in preclinical or clinical experimentation, and if coupled with leukemia-directed therapies, could represent a valuable option to improve the prognosis of relapsed/refractory patients, whose management represents an unmet medical need.

Reduction of Activin Receptor-Like Kinase 4 Expression Ameliorates Myocardial Ischemia/Reperfusion Injury through Inhibiting TGFβ Signaling Pathway

The activation of activin receptor-like kinase 4 (ALK4) signaling plays a pivotal role in the pressure-overloaded heart, and haplodeficiency of ALK4 can alleviate cardiac fibrosis secondary to myocardial infarction and preserve cardiac function through partially inactivating the Smad3/4 pathway. However, whether transforming growth factor (TGF) β signaling is involved in the beneficial effects of ALK4 knockdown on the ischemic heart is still unclear. This study was undertaken to investigate the change in the TGFβ signaling after ALK4 knockdown in vivo and in vitro. Forty C57BL/6J mice were randomized into ALK4^+/- ischemia/reperfusion (I/R) group (ALK4^+/-+I/R, n = 10), ALK4^+/- sham group (ALK4^+/-+sham, n = 10), wild-type sham group (WT+sham, n = 10), and WT I/R group (WT+I/R, n = 10). Heart histology and the levels of cytokines related to antioxidant and inflammation, as well as protein and mRNA expressions of molecules associated with TGFβ pathway, were examined in different groups. Our results showed that the reduction of ALK4 expression ameliorated myocardial I/R injury through inhibiting TGFβ signaling pathway. Our findings indicate that ALK4 may become a novel target for the therapy of myocardial I/R injury.

MicroRNA Signature of Epithelial-Mesenchymal Transition in Group B Streptococcal Infection of the Placental Chorioamniotic Membranes

BACKGROUND

Infection-induced preterm birth is a major cause of neonatal mortality and morbidity and leads to preterm premature rupture of placental chorioamniotic membranes. The loss of amniotic epithelial cells and tensile strength preceding membrane rupture is poorly understood. We hypothesized that intrauterine bacterial infection induces changes in microRNA (miRNA) expression, leading to amniotic epithelial cell loss and membrane weakening.

METHODS

Ten pregnant pigtail macaques received choriodecidual inoculation of either group B Streptococcus (GBS) or saline (n = 5/group). Placental chorioamniotic membranes were studied using RNA microarray and immunohistochemistry. Chorioamniotic membranes from women with preterm premature rupture of membranes (pPROM) and normal term pregnancies were studied using transmission electron microscopy.

RESULTS

In our model, an experimental GBS infection was associated with changes in the miRNA profile in the chorioamniotic membranes consistent with epithelial to mesenchymal transition (EMT) with loss of epithelial (E-cadherin) and gain of mesenchymal (vimentin) markers. Similarly, loss of desmosomes (intercellular junctions) was seen in placental tissues from women with pPROM.

CONCLUSIONS

We describe EMT as a novel mechanism for infection-associated chorioamniotic membrane weakening, which may be a common pathway for many etiologies of pPROM. Therapy based on anti-miRNA targeting of EMT may prevent pPROM due to perinatal infection.

Activin A: an emerging target for improving cancer treatment?

INTRODUCTION

Activin A is involved in the regulation of a surprisingly broad number of processes that are relevant for cancer development and treatment; it is implicated in cell autonomous functions and multiple regulatory functions in the tumor microenvironment.

AREAS COVERED

This article summarizes the current knowledge about activin A in cell growth and death, migration and metastasis, angiogenesis, stemness and drug resistance, regulation of antitumor immunity, and cancer cachexia. We explore the role of activin A as a biomarker and discuss strategies for using it as target for cancer therapy. Literature retrieved from Medline until 25 June 2020 was considered.

EXPERT OPINION

While many functions of activin A were investigated in preclinical models, there is currently limited experience from clinical trials. Activin A has growth- and migration-promoting effects, contributes to immune evasion and cachexia and is associated with shorter survival in several cancer types. Targeting activin A could offer the chance to simultaneously limit tumor growth and spreading, improve drug response, boost antitumor immune responses and improve cancer-associated or treatment-associated cachexia, bone loss, and anemia. Nevertheless, defining which patients have the highest likelihood of benefiting from these effects is challenging and will require further work.

CFIm25-regulated lncRNA acv3UTR promotes gastric tumorigenesis via miR-590-5p/YAP1 axis

Accumulating evidences indicate that 3ʹUTR of the coding gene can act as crucial regulators in gastric cancer (GC). However, the detailed mechanisms and responsive targets are not well established. Here, we found that acvr1b gene 3ʹUTR (acv3UTR) was elevated in GC tissue, the expression of which was significantly correlated with advanced pTNM-stage and poor outcome in clinical patients. Forced expression of acv3UTR promoted GC cells growth in vitro and in vivo. Mechanistically, our results suggested that acv3UTR functioned as an oncogenic competing endogenous RNA via sponging miR-590-5p and enhancing YAP1 level. Tumor suppressor miR-590-5p was a molecular module in acv3UTR regulatory axis, the forced expression of which led to impairing of oncogenic potential of acv3UTR. The positive correlation of acv3UTR and YAP1 expression, and the negative correlation of acv3UTR and miR-590-5p expression, were verified in GC patients. Moreover, CFIm25 was identified as a key regulator contributing to acv3UTR aberrant expression in GC binding to UGUA-264 motif. Overall, our finding defines a mechanism for understanding the potential role of acv3UTR transcription in GC tumorigenesis, and indicates a correlation between 3ʹUTR trans-regulatory effect and GC development.

miR-15a/miR-16 cluster inhibits invasion of prostate cancer cells by suppressing TGF-β signaling pathway

BACKGROUND

To determine whether and how miR15a/16 regulate TGF-β signaling pathways during the progression of prostate cancer.

METHODS

We used bioinformatics prediction, reporter gene assay, real-time PCR, Matrigel invasion assay and Western blot to dissect the molecular mechanism of how miR-15a/miR-16 may cause metastasis in prostate tumor.

RESULTS

MiR-15a/16 targeted and inhibited the expression of endogenous Smad3 and ACVR2A proteins. The overexpression of miR15a/16 down-regulated p-smad3 expression, affected the expression of both MMP2 and E-cadherin, and down-regulated the expression of the EMT-mediated factors Snail and Twist in LNCaP prostate cancer cells. The overexpression of miR15a/16 decreased the invasion of LNCaP cells. MiR-15a/miR-16 cluster could reverse the invasion of activin A-mediated prostate cancer cells. After the inhibition of the activin/smad signaling pathway, the inhibitory effect of invasion in prostate cancer cells by miR-15a/miR-16 cluster disappeared.

CONCLUSION

Our data indicated that miR15a/16 inhibited the components of TGF-β signaling pathways in LNCaP cell line, which might relate to the progression and metastasis of prostate cancer.

Presurgical weight loss affects tumour traits and circulating biomarkers in men with prostate cancer

Background:

Obesity is associated with aggressive prostate cancer. To explore whether weight loss favourably affects tumour biology and other outcomes, we undertook a presurgical trial among overweight and obese men with prostate cancer.

Methods:

This single-blinded, two-arm randomised controlled trial explored outcomes of a presurgical weight loss intervention (WLI) that promoted ∼1 kg per week loss via caloric restriction and increased physical activity (PA). Forty overweight/obese men with clinically confirmed prostate cancer were randomised to the WLI presurgery or to a control arm; changes in weight, body composition, quality-of-life, circulating biomarkers, gene expression, and immunohistochemical markers in tumour and benign prostatic tissue were evaluated.

Results:

The study period averaged 50 days. Mean (s.d.) change scores for the WLI vs control arms were as follows: weight: −4.7 (3.1) kg vs −2.2 (4.4) kg (P=0.0508); caloric intake: −500 (636) vs −159 (600) kcal per day (P=0.0034); PA: +0.9 (3.1) vs +1.7 (4.6) MET-hours per day (NS); vitality: +5.3 (7.l4) vs −1.8 (8.1) (P=0.0491); testosterone: +55.1 (86.0) vs −48.3 (203.7) ng dl⁻¹ (P=0.0418); sex hormone-binding globulin: +14.0 (14.6) vs +1.8 (7.6) nmol l⁻¹ (P=0.0023); and leptin: −2.16 (2.6) vs −0.03 (3.75) (P=0.0355). Follow-up Ki67 was significantly higher in WLI vs control arms; median (interquartile range): 5.0 (2.5,10.0) vs 0.0 (0.0,2.5) (P=0.0061) and several genes were upregulated, for example, CTSL, GSK3B, MED12, and LAMC2.

Conclusions:

Intentional weight loss shows mixed effects on circulating biomarkers, tumour gene expression, and proliferative markers. More study is needed before recommending weight loss, in particular rapid weight loss, among men with prostate cancer.

Haplodeficiency of activin receptor-like kinase 4 alleviates myocardial infarction-induced cardiac fibrosis and preserves cardiac function

Cardiac fibrosis (CF), a repairing process following myocardial infarction (MI), is characterized by abnormal proliferation of cardiac fibroblasts and excessive deposition of extracellular matrix (ECM) resulting in inevitable resultant heart failure. TGF-β (transforming growth factor-β)/ALK5 (Activin receptor-like kinase 5)/Smad2/3/4 pathways have been reported to be involved in the process. Recent studies have implicated both activin and its specific downstream component ALK4 in stimulating fibrosis in non-cardiac organs. We recently reported that ALK4 is upregulated in the pressure-overloaded heart and its partial inhibition attenuated the pressure overload-induced CF and cardiac dysfunction. However, the role of ALK4 in the pathogenesis of MI-induced CF, which is usually more severe than that induced by pressure-overload, remains unknown. Here we report: 1) In a wild-type mouse model of MI, ALK4 upregulation was restricted in the fibroblasts of the infarct border zone; 2) In contrast, ALK4^+/- mice with a haplodeficiency of ALK4 gene, showed a significantly attenuated CF in the border zone, with a smaller scar size, a preserved cardiac function and an improved survival rate post-MI; 3) Similarly to pressure-overloaded heart, these beneficial effects might be through a partial inactivation of the Smad3/4 pathway but not MAPK cascades; 4) The apoptotic rate of the cardiomyocytes were indistinguishable in the border zone of the wild-type control and ALK4^+/- mice; 5) Cardiac fibroblasts isolated from ALK4^+/- mice showed reduced migration, proliferation and ECM synthesis in response to hypoxia. These results indicate that partial inhibition of ALK4 may reduce MI-induced CF, suggesting ALK4 as a novel target for inhibition of unfavorable CF and for preservation of LV systolic function induced by not only pressure-overload but also MI.

Cancer-targeted therapies and radiopharmaceuticals

The treatment of bone metastases remains a clinical challenge. Although a number of well-established agents, namely bisphosphonates and denosumab, are available to reduce the occurrence of skeletal-related events, additional cancer-targeted therapies are required to improve patients' prognosis and quality of life. This review focuses on novel targets and agents that are under clinical evaluation for the treatment of malignant bone diseases such as activin A, src and endothelin-1 inhibition or agents that are clinically approved and may positively influence bone, such as the mTOR inhibitor everolimus. In addition, the potential of alpharadin, a novel radiopharmaceutical approved for the treatment of prostatic bone disease, is discussed.

Activation of activin type IB receptor signals in pancreatic β cells leads to defective insulin secretion through the attenuation of ATP-sensitive K+ channel activity

In studies of gene-ablated mice, activin signaling through activin type IIB receptors (ActRIIB) and Smad2 has been shown to regulate not only pancreatic β cell mass but also insulin secretion. However, it still remains unclear whether gain of function of activin signaling is involved in the modulation of pancreatic β cell mass and insulin secretion. To identify distinct roles of activin signaling in pancreatic β cells, the Cre-loxP system was used to activate signaling through activin type IB receptor (ActRIB) in pancreatic β cells. The resultant mice (pancreatic β cell-specific ActRIB transgenic (Tg) mice; ActRIBCAβTg) exhibited a defect in glucose-stimulated insulin secretion (GSIS) and a progressive impairment of glucose tolerance. Patch-clamp techniques revealed that the activity of ATP-sensitive K(+) channels (KATP channels) was decreased in mutant β cells. These results indicate that an appropriate level of activin signaling may be required for GSIS in pancreatic β cells, and that activin signaling involves modulation of KATP channel activity.

Endocrine aspects of bone metastases

Skeletal lesions are a frequent complication of breast and prostate cancer and a hallmark of multiple myeloma. Endocrine and paracrine factors modulate various aspects of bone metastases, including tumour proliferation, skeletal susceptibility to tumour homing, the microenvironment needed to support tumour persistence, and the initiation of a vicious cycle between tumour and bone-resident cells that further promotes tumour growth. Endocrine changes, such as oestrogen or vitamin D deficiency, contribute to a fertile bone microenvironment that might promote bone metastases. Bone health could be impaired further by existing cancer treatments, especially sex hormone deprivation. In this Review, we discuss the effect of hormones and associated local factors on cross-talk between bone metabolism and tumour biology. We review the biology of osteolytic and osteosclerotic lesions, with a focus on endocrine aspects, and outline potential therapeutic targets. We also summarise endocrine aspects of the pathogenesis and clinical presentation of bone metastases and provide an update on existing and future treatments.