Soluble bone-derived osteopontin promotes migration and stem-like behavior of breast cancer cells

Osteopontin: A Key Multifaceted Regulator in Tumor Progression and Immunomodulation

The tumor microenvironment (TME) is composed of various cellular components such as tumor cells, stromal cells including fibroblasts, adipocytes, mast cells, lymphatic vascular cells and infiltrating immune cells, macrophages, dendritic cells and lymphocytes. The intricate interplay between these cells influences tumor growth, metastasis and therapy failure. Significant advancements in breast cancer therapy have resulted in a substantial decrease in mortality. However, existing cancer treatments frequently result in toxicity and nonspecific side effects. Therefore, improving targeted drug delivery and increasing the efficacy of drugs is crucial for enhancing treatment outcome and reducing the burden of toxicity. In this review, we have provided an overview of how tumor and stroma-derived osteopontin (OPN) plays a key role in regulating the oncogenic potential of various cancers including breast. Next, we dissected the signaling network by which OPN regulates tumor progression through interaction with selective integrins and CD44 receptors. This review addresses the latest advancements in the roles of splice variants of OPN in cancer progression and OPN-mediated tumor-stromal interaction, EMT, CSC enhancement, immunomodulation, metastasis, chemoresistance and metabolic reprogramming, and further suggests that OPN might be a potential therapeutic target and prognostic biomarker for the evolving landscape of cancer management.

The Role of Breast Cancer Cells in Bone Metastasis: Suitable Seeds for Nourishing Soil

PURPOSE OF REVIEW

The purpose of this review was to describe the characteristics of breast cancer cells prone to developing bone metastasis and determine how they are regulated by the bone microenvironment.

RECENT FINDINGS

The bone is a site of frequent breast cancer metastasis. Bone metastasis accounts for 70% of advanced breast cancer cases and remains incurable. It can lead to skeletal-related events, such as bone fracture and pain, and seriously affect the quality of life of patients. Breast cancer cells escape from the primary lesion and spread to the bone marrow in the early stages. They can then enter the dormant state and restore tumourigenicity after several years to develop overt metastasis. In the last few years, an increasing number of studies have reported on the factors promoting bone metastasis of breast cancer cells, both at the primary and metastatic sites. Identifying factors associated with bone metastasis aids in the early recognition of bone metastasis tendency. How to target these factors and minimize the side effects on the bone remains to be further explored.

SPP1 mRNA determination based on molecular beacon for the recurrence prognosis of bladder cancer

Background

Bladder cancer (BC) has attracted significant attention on account of its recurrence as well as mortality. Tumor recurrence plays a significant role in cancer patients' individual treatment. Secreted phosphoprotein 1 (SPP1) has been recognized as a potential target for treating BC and served as a useful biomarker for prognosis; it is commonly tested by immunohistochemistry (IHC). However, this conventional method has the disadvantage of being time-consuming and costly. This study aimed to develop a molecular beacon (MB) for the detection of SPP1 messenger RNA (mRNA) for the recurrence prognosis of BC.

Methods

An MB was constructed and applied to image SPP1 mRNA level at both molecular and cellular level. The fluorescence spectra were recorded with a fluorescence spectrophotometer. The effect of SPP1 MB toward the cell viability was performed by Cell Counting Kit-8 (CCK-8) assays. The SPP1 mRNA expression level was measured by quantitative real-time polymerase chain reaction (qRT-PCR). Cancer cells and tissues were analyzed with confocal fluorescence imaging. Correlation, sensitivity, and specificity parameters were calculated.

Results

It was demonstrated that both cancer cells and BC tissues expressed high signal which reflected the expression of SPP1. In addition, 42 cases were detected by MB and divided into two groups according to the fluorescence intensity. The results further suggested that highly expressed SPP1 could predict early tumor recurrence in BC.

Conclusions

The SPP1 MB could be applied as an appropriate approach to predict BC recurrence and patients' prognosis.

Role of osteopontin in cancer development and treatment

Osteopontin (OPN) is a multifunctional protein secreted intracellularly and extracellularly by various cell types, including NK cells, macrophages, osteoblasts, T cells, and cancer cells. Owing to its diverse distribution, OPN plays a role in cell proliferation, stem-cell-like properties, epithelial-mesenchymal transformation, glycolysis, angiogenesis, fibrosis, invasion, and metastasis. In this review, we discuss recent findings, interpret representative studies on OPN expression in cancer, clarify that elevated OPN levels are observed in multiple cancer types (including colorectal, breast, lung, and liver cancer), and explore how OPN-macrophage interactions shape the tumor microenvironment. We also summarize progress in OPN research with regard to tumor therapy, which can facilitate the development of novel anti-tumor treatment strategies.

VNLG-152R and its deuterated analogs potently inhibit/repress triple/quadruple negative breast cancer of diverse racial origins in vitro and in vivo by upregulating E3 Ligase Synoviolin 1 (SYVN1) and inducing proteasomal degradation of MNK1/2

Triple-negative breast cancer (TNBC) and its recently identified subtype, quadruple negative breast cancer (QNBC), collectively account for approximately 13% of reported breast cancer cases in the United States. These aggressive forms of breast cancer are associated with poor prognoses, limited treatment options, and lower overall survival rates. In previous studies, our research demonstrated that VNLG-152R exhibits inhibitory effects on TNBC cells both in vitro and in vivo and the deuterated analogs were more potent inhibitors of TNBC cells in vitro. Building upon these findings, our current study delves into the molecular mechanisms underlying this inhibitory action. Through transcriptome and proteome analyses, we discovered that VNLG-152R upregulates the expression of E3 ligase Synoviolin 1 (SYVN1), also called 3-hydroxy-3-methylglutaryl reductase degradation (HRD1) in TNBC cells. Moreover, we provide genetic and pharmacological evidence to demonstrate that SYVN1 mediates the ubiquitination and subsequent proteasomal degradation of MNK1/2, the only known kinases responsible for phosphorylating eIF4E. Phosphorylation of eIF4E being a rate-limiting step in the formation of the eIF4F translation initiation complex, the degradation of MNK1/2 by VNLG-152R and its analogs impedes dysregulated translation in TNBC cells, resulting in the inhibition of tumor growth. Importantly, our findings were validated in vivo using TNBC xenograft models derived from MDA-MB-231, MDA-MB-468, and MDA-MB-453 cell lines, representing different racial origins and genetic backgrounds. These xenograft models, which encompass TNBCs with varying androgen receptor (AR) expression levels, were effectively inhibited by oral administration of VNLG-152R and its deuterated analogs in NRG mice. Importantly, in direct comparison, our compounds are more effective than enzalutamide and docetaxel in achieving tumor growth inhibition/repression in the AR+ MDA-MD-453 xenograft model in mice. Collectively, our study sheds light on the involvement of SYVN1 E3 ligase in the VNLG-152R-induced degradation of MNK1/2 and the therapeutic potential of VNLG-152R and its more potent deuterated analogs as promising agents for the treatment of TNBC across diverse patient populations.

Spatially patterned 3D model mimics key features of cancer metastasis to bone

Bone is the most common target of metastasis in breast cancer and prostate cancer, leading to significant mortality due to lack of effective treatments. The discovery of novel therapies has been hampered by a lack of physiologically relevant in vitro models that can mimic key clinical features of bone metastases. To fill this critical gap, here we report spatially patterned, tissue engineered 3D models of breast cancer and prostate cancer bone metastasis which mimic bone-specific invasion, cancer aggressiveness, cancer-induced dysregulation of bone remodeling, and in vivo drug response. We demonstrate the potential of integrating such 3D models with single-cell RNA sequencing to identify key signaling drivers of cancer metastasis to bone. Together, these results validate that spatially patterned 3D bone metastasis models mimic key clinical features of bone metastasis and can serve as a novel research tool to elucidate bone metastasis biology and expedite drug discovery.

SPP1 as a key gene in the lymph node metastasis and a potential predictor of poor prognosis in head and neck carcinoma

BACKGROUND

Lymph node metastasis (LNM) is an important cause leading to recurrence and development of head and neck carcinoma (HNC), with the precise mechanisms unclear. Thus, we aimed to identify the key genes involved in LNM and further evaluate their expressions and roles.

METHODS

A cohort of HNC in the TCGA was analyzed. The study involved three phases (one screening and two validation phases). First, the differentially expressed genes regarding LNM were screened, from which a key gene was identified by a series of data mining approaches. Then, the expressions and roles of the key gene were validated in HNC through bioinformatics. Afterward, the expression of the key gene was detected by qPCR, western blot, and Immunohistochemistry based on a cell model and a tissue microarray. Further, colony formation and transwell migration and invasion assays were used to evaluate the roles of the key gene.

RESULTS

SPP1 was overexpressed in HNC tissues and was identified as the key gene. Overexpression of SPP1 in HNC was correlated with advanced pathological stages and T-stage, as well as the presence of LNM, which predicted poor prognosis. The expression of SPP1 was closely associated with the infiltration of immune cells in HNC, especially M2 macrophages. Lab experiments confirmed that SPP1 silence in HNC cells resulted in weakened invasive and metastatic abilities.

CONCLUSION

This study reveals that SPP1 may be a key gene associated with LNM in HNC, raising the possibility of SPP1 as a target for HNC prevention and treatment. This article is protected by copyright. All rights reserved.

WNK1 in Malignant Behaviors: A Potential Target for Cancer?

Metastasis is the major cause of mortality in cancer patients. Analyses of mouse models and patient data have implicated the protein kinase WNK1 as one of a handful of genes uniquely linked to a subset of invasive cancers. WNK1 signaling pathways are widely implicated in the regulation of ion co-transporters and in controlling cell responses to osmotic stress. In this review we will discuss its actions in tumor malignancy in human cancers and present evidence for its function in invasion, migration, angiogenesis and mesenchymal transition.

PCF11, a Novel CD44-Downstream Transcriptional Target, Linking Its 3'-End Polyadenylation Function to Tumor Cell Metastasis

Breast Cancer (BC) is the most common and the major health issue in women worldwide. Metastasis, a multistep process, is the worst aspect of cancer and tumor cell invasion is the defining step. Tumor cell invasion requires cell adhesion molecules (CAMs), and alterations in CAMs is considered as an initiating event in metastasis. Among CAMs, CD44 is a large family of more than 100 isoform, and its precise function was initially controversial in BC. Therefore, we have previously established a (Tet)-off inducible expression system of CD44 in MCF-7 primary BC cell line, and showed that CD44 promoted BC invasion/metastasis both in vitro and in vivo. A microarray gene expression profiling revealed more than 200 CD44-downstream potential transcriptional target genes, mediating its role in BC cell invasion and metastasis. Among these CD44-target genes, the Pre-mRNA cleavage complex 2 protein (PCF11) was upregulated upon the activation of CD44 by its major ligand hyaluronan (HA); This prompted us to hypothesize PCF11 as a potential novel transcriptional target of CD44-promoted BC cell invasion and metastasis. A large body of evidence from the literature supports our hypothesis that CD44 might regulate PCF11 via MAPK/ERK pathway. This review aims to discuss these findings from the literature that support our hypothesis, and further provide possible mechanisms linking CD44-promoted cell invasion through regulation of its potential target PCF11.

Bone-kidney axis: A potential therapeutic target for diabetic nephropathy

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease (ESRD). However, its pathogenesis remains unclear, and effective prevention and treatment strategies are lacking. Recently, organ-to-organ communication has become a new focus of studies on pathogenesis. Various organs or tissues (the liver, muscle and adipose tissue) secrete a series of proteins or peptides to regulate the homeostasis of distal organs in an endocrine manner. Bone, an important part of the body, can also secrete bone-derived proteins or peptides that act on distal organs. As an organ with high metabolism, the kidney is responsible for signal and material exchange with other organs at any time through circulation. In this review, we briefly discussed bone composition and changes in bone structure and function in DN and summarized the current status of bone-derived proteins and their role in the progression of DN. We speculated that the "bone-kidney axis" is a potential target for early diagnosis and treatment of DN.

Heterogeneity of BCSCs contributes to the metastatic organotropism of breast cancer

Breast cancer is one of the most-common female malignancies with a high risk of relapse and distant metastasis. The distant metastasis of breast cancer exhibits organotropism, including brain, lung, liver and bone. Breast cancer stem cells (BCSCs) are a small population of breast cancer cells with tumor-initiating ability, which participate in regulating distant metastasis in breast cancer. We investigated the heterogeneity of BCSCs according to biomarker status, epithelial or mesenchymal status and other factors. Based on the classical “seed and soil” theory, we explored the effect of BCSCs on the metastatic organotropism in breast cancer at both “seed” and “soil” levels, with BCSCs as the “seed” and BCSCs-related microenvironment as the “soil”. We also summarized current clinical trials, which assessed the safety and efficacy of BCSCs-related therapies. Understanding the role of BCSCs heterogeneity for regulating metastatic organotropism in breast cancer would provide a new insight for the diagnosis and treatment of advanced metastatic breast cancer.

Bone Metastatic Breast Cancer: Advances in Cell Signaling and Autophagy Related Mechanisms

Bone metastasis is a frequent complication of breast cancer with nearly 70% of metastatic breast cancer patients developing bone metastasis during the course of their disease. The bone represents a dynamic microenvironment which provides a fertile soil for disseminated tumor cells, however, the mechanisms which regulate the interactions between a metastatic tumor and the bone microenvironment remain poorly understood. Recent studies indicate that during the metastatic process a bidirectional relationship between metastatic tumor cells and the bone microenvironment begins to develop. Metastatic cells display aberrant expression of genes typically reserved for skeletal development and alter the activity of resident cells within the bone microenvironment to promote tumor development, resulting in the severe bone loss. While transcriptional regulation of the metastatic process has been well established, recent findings from our and other research groups highlight the role of the autophagy and secretory pathways in interactions between resident and tumor cells during bone metastatic tumor growth. These reports show high levels of autophagy-related markers, regulatory factors of the autophagy pathway, and autophagy-mediated secretion of matrix metalloproteinases (MMP's), receptor activator of nuclear factor kappa B ligand (RANKL), parathyroid hormone related protein (PTHrP), as well as WNT5A in bone metastatic breast cancer cells. In this review, we discuss the recently elucidated mechanisms and their crosstalk with signaling pathways, and potential therapeutic targets for bone metastatic disease.

Cancer-associated mesothelial cells promote ovarian cancer chemoresistance through paracrine osteopontin signaling

Ovarian cancer is the leading cause of gynecological malignancy-related deaths, due to its widespread intraperitoneal metastases and acquired chemoresistance. Mesothelial cells are an important cellular component of the ovarian cancer microenvironment that promote metastasis. However, their role in chemoresistance is unclear. Here, we investigated whether cancer-associated mesothelial cells promote ovarian cancer chemoresistance and stemness in vitro and in vivo. We found that osteopontin is a key secreted factor that drives mesothelial-mediated ovarian cancer chemoresistance and stemness. Osteopontin is a secreted glycoprotein that is clinically associated with poor prognosis and chemoresistance in ovarian cancer. Mechanistically, ovarian cancer cells induced osteopontin expression and secretion by mesothelial cells through TGF-β signaling. Osteopontin facilitated ovarian cancer cell chemoresistance via the activation of the CD44 receptor, PI3K/AKT signaling, and ABC drug efflux transporter activity. Importantly, therapeutic inhibition of osteopontin markedly improved the efficacy of cisplatin in both human and mouse ovarian tumor xenografts. Collectively, our results highlight mesothelial cells as a key driver of ovarian cancer chemoresistance and suggest that therapeutic targeting of osteopontin may be an effective strategy for enhancing platinum sensitivity in ovarian cancer.

WNK1 Enhances Migration and Invasion in Breast Cancer Models

Metastasis is the major cause of mortality in patients with breast cancer. Many signaling pathways have been linked to cancer invasiveness, but blockade of few protein components has succeeded in reducing metastasis. Thus, identification of proteins contributing to invasion that are manipulable by small molecules may be valuable in inhibiting spread of the disease. The protein kinase with no lysine (K) 1 (WNK1) has been suggested to induce migration of cells representing a range of cancer types. Analyses of mouse models and patient data have implicated WNK1 as one of a handful of genes uniquely linked to invasive breast cancer. Here, we present evidence that inhibition of WNK1 slows breast cancer metastasis. We show that depletion or inhibition of WNK1 reduces migration of several breast cancer cell lines in wound healing assays and decreases invasion in collagen matrices. Furthermore, WNK1 depletion suppresses expression of AXL, a tyrosine kinase implicated in metastasis. Finally, we demonstrate that WNK inhibition in mice attenuates tumor progression and metastatic burden. These data showing reduced migration, invasion, and metastasis upon WNK1 depletion in multiple breast cancer models suggest that WNK1 contributes to the metastatic phenotype, and that WNK1 inhibition may offer a therapeutic avenue for attenuating progression of invasive breast cancers.

Reporters of Cancer Stem Cells as a Tool for Drug Discovery

In view of the importance of cancer stem cells (CSCs) in chemoresistance, metastasis and recurrence, the biology of CSCs were explored in detail. Based on that, several modalities were proposed to target them. In spite of the several clinical trials, a successful CSC-targeting drug is yet to be identified. The number of molecules screened and entered for clinical trial for CSC-targeting is comparatively low, compared to other drugs. The bottle neck is the lack of a high-throughput adaptable screening strategy for CSCs. This review is aimed to identify suitable reporters for CSCs that can be used to identify the heterogeneous CSC populations, including quiescent CSCs, proliferative CSCs, drug resistant CSCs and metastatic CSCs. Analysis of the tumor microenvironment regulating CSCs revealed that the factors in CSC-niche activates effector molecules that function as CSC markers, including pluripotency markers, CD133, ABCG2 and ALDH1A1. Among these factors OCT4, SOX2, NANOG, ABCG2 and ALDH1A1 are ideal for making reporters for CSCs. The pluripotency molecules, like OCT4, SOX2 and NANOG, regulate self-renewal, chemoresistance and metastasis. ABCG2 is a known regulator of drug resistance while ALDH1A1 modulates self-renewal, chemoresistance and metastasis. Considering the heterogeneity of CSCs, including a quiescent population and a proliferative population with metastatic ability, we propose the use of a combination of reporters. A dual reporter consisting of a pluripotency marker and a marker like ALDH1A1 will be useful in screening drugs that target CSCs.

Tumor-derived osteopontin drives the resident fibroblast to myofibroblast differentiation through Twist1 to promote breast cancer progression

Tumor-stroma interactions are important determinants for the disease course in cancer. While stromal influence has been known to often play a tumor-promoting role, incomplete mechanistic insight into this phenomenon has prevented its therapeutic targeting. Stromal fibroblasts can be activated by tumor cells to differentiate into cancer-associated fibroblasts (CAFs), that exhibit the traits of myofibroblasts, and in turn, they increase cancer aggressiveness. Here, we report the crosstalk between the cancer cells and stromal fibroblasts that leads to tumor progression. The process is initiated by secretion of a chemokine like protein, osteopontin (OPN) from the cancer cells that differentiates the fibroblasts to myofibroblasts. Tumor-derived OPN achieves this transition by engaging CD44 and αvβ3 integrins on the fibroblast surface, which mediates signaling via Akt and ERK to induce Twist1-dependent gene expression. The OPN-driven CAFs then secrete CXCL12, which in turn triggers epithelial to mesenchymal transition (EMT) in the tumor cells. OPN, produced by the cancer cells, and CXCL12, secreted by activated fibroblasts, are necessary and sufficient to perpetuate the crosstalk. Knocking out OPN in carcinogen-induced mammary tumors or knocking down OPN in cancer cells and fibroblast co-implanted xenografts abrogates myofibroblast differentiation, Twist1, and CXCL12 expression. OPN expression is correlated with CAF-specific gene signature as shown by breast tumor tissue microarray consisting of 100 patient specimens. Bioinformatics analyses have confirmed that the expression of OPN is significantly correlated with the expression of myofibroblast-specific markers as demonstrated in human breast carcinoma dataset of 2509 patients. Our findings describe OPN and CXCL12 act as compelling targets to curb the tumor-promoting features of the stromal components and further suggested that OPN-regulated CXCL12 network might act as potential therapeutic target for the management of CAF-mediated breast cancer progression.

Understanding the role of integrins in breast cancer invasion, metastasis, angiogenesis, and drug resistance

Integrins are cell adhesion receptors, which are typically transmembrane glycoproteins that connect to the extracellular matrix (ECM). The function of integrins regulated by biochemical events within the cells. Understanding the mechanisms of cell growth by integrins is important in elucidating their effects on tumor progression. One of the major events in integrin signaling is integrin binding to extracellular ligands. Another event is distant signaling that gathers chemical signals from outside of the cell and transmit the signals upon cell adhesion to the inside of the cell. In normal breast tissue, integrins function as checkpoints to monitor effects on cell proliferation, while in cancer tissue these functions altered. The combination of tumor microenvironment and its associated components determines the cell fate. Hypoxia can increase the expression of several integrins. The exosomal integrins promote the growth of metastatic cells. Expression of certain integrins is associated with increased metastasis and decreased prognosis in cancers. In addition, integrin-binding proteins promote invasion and metastasis in breast cancer. Targeting specific integrins and integrin-binding proteins may provide new therapeutic approaches for breast cancer therapies. This review will examine the current knowledge of integrins' role in breast cancer.

The Tumor Microenvironment as a Driving Force of Breast Cancer Stem Cell Plasticity

Simple Summary

Breast cancer stem cells are a subset of transformed cells that sustain tumor growth and can metastasize to secondary organs. Since metastasis accounts for most cancer deaths, it is of paramount importance to understand the cellular and molecular mechanisms that regulate this subgroup of cells. The tumor microenvironment (TME) is the habitat in which transformed cells evolve, and it is composed by many different cell types and the extracellular matrix (ECM). A body of evidence strongly indicates that microenvironmental cues modulate stemness in breast cancer, and that the coevolution of the TME and cancer stem cells determine the fate of breast tumors. In this review, we summarize the studies providing links between the TME and the breast cancer stem cell phenotype and we discuss their specific interactions with immune cell subsets, stromal cells, and the ECM.

Abstract

Tumor progression involves the co-evolution of transformed cells and the milieu in which they live and expand. Breast cancer stem cells (BCSCs) are a specialized subset of cells that sustain tumor growth and drive metastatic colonization. However, the cellular hierarchy in breast tumors is rather plastic, and the capacity to transition from one cell state to another depends not only on the intrinsic properties of transformed cells, but also on the interplay with their niches. It has become evident that the tumor microenvironment (TME) is a major player in regulating the BCSC phenotype and metastasis. The complexity of the TME is reflected in its number of players and in the interactions that they establish with each other. Multiple types of immune cells, stromal cells, and the extracellular matrix (ECM) form an intricate communication network with cancer cells, exert a highly selective pressure on the tumor, and provide supportive niches for BCSC expansion. A better understanding of the mechanisms regulating these interactions is crucial to develop strategies aimed at interfering with key BCSC niche factors, which may help reducing tumor heterogeneity and impair metastasis.

Bone Marrow Adipocytes, Adipocytokines, and Breast Cancer Cells: Novel Implications in Bone Metastasis of Breast Cancer

Accumulating discoveries highlight the importance of interaction between marrow stromal cells and cancer cells for bone metastasis. Bone is the most common metastatic site of breast cancer and bone marrow adipocytes (BMAs) are the most abundant component of the bone marrow microenvironment. BMAs are unique in their origin and location, and recently they are found to serve as an endocrine organ that secretes adipokines, cytokines, chemokines, and growth factors. It is reasonable to speculate that BMAs contribute to the modification of bone metastatic microenvironment and affecting metastatic breast cancer cells in the bone marrow. Indeed, BMAs may participate in bone metastasis of breast cancer through regulation of recruitment, invasion, survival, colonization, proliferation, angiogenesis, and immune modulation by their production of various adipocytokines. In this review, we provide an overview of research progress, focusing on adipocytokines secreted by BMAs and their potential roles for bone metastasis of breast cancer, and investigating the mechanisms mediating the interaction between BMAs and metastatic breast cancer cells. Based on current findings, BMAs may function as a pivotal modulator of bone metastasis of breast cancer, therefore targeting BMAs combined with conventional treatment programs might present a promising therapeutic option.

Osteopontin Regulates Endometrial Stromal Cell Migration in Endometriosis through the PI3K Pathway : Osteopontin Regulates Endometrial Cell Migration in Endometriosis

Endometriosis is generally characterized as a tumor-like disease because of its potential for distant metastasis and local tissue invasion, while whether osteopontin (OPN) plays a role in the pathogenesis of endometriosis has not been thoroughly investigated. We investigated the expression of OPN, urokinase plasminogen activator (uPA), phosphatidylinositol 3 kinase (PI3K), and phospho-PI3 kinase (p-PI3K) in endometrial stromal cells (ESCs). The serum concentration of OPN was determined by enzyme-linked immunosorbent assays (ELISA). OPN was downregulated to explore the corresponding change of uPA, p-PI3K, F-actin, and α-tubulin. The expression of OPN, uPA, PI3K, and p-PI3K was evaluated by western blot and quantitative real-time PCR (RT-qPCR) and the expression of F-actin and α-tubulin was confirmed by immunofluorescence assay. The proliferation and migration abilities of ESCs were investigated by CCK8, transwell, and wound scratch assays. Endometrial OPN, p-PI3K, and uPA expressions and serum OPN levels were increased in patients with endometriosis compared with the control. The expressions of p-PI3K, uPA, and α-tubulin were decreased by siRNA-OPN interference in ectopic ESCs. Activation and inhibition of the PI3K pathway apparently upregulate and downregulate uPA expression. Knockdown of OPN and inhibition of the PI3K pathway remarkably inhibited cell migration in ectopic ESCs. Meanwhile, activation of the PI3K pathway promoted the migration ability of ectopic ESCs. OPN may regulate the expression of uPA through the PI3K signal pathway to affect the migration ability of ESCs, indicating that OPN, uPA, and the PI3K pathway may be potential targets for interrupting development of endometriosis.

Immunohistochemical evaluation of osteopontin expression in triple-negative breast cancer

Introduction

Triple-negative breast cancer (TNBC) is associated with lack of expression of estrogen and progesterone receptors and HER2 and is the subgroup of breast cancers with the worst prognosis. Osteopontin is a phosphorylated glycoprotein whose overexpression may occur in pathological states such as cancers. The main purpose of our study was to evaluate the immunohistochemical expression of osteopontin in connection with the analysis of recognized clinical and pathological prognostic factors in primary sites of TNBC with and without lymph node metastases.

Material and methods

The immunohistochemical evaluation of osteopontin expression in 35 women with TNBC, chosen from a group of 726 patients, was performed. The material came from the excisional biopsies of primary breast cancers and total mastectomies.

Results

All patients showed expression of osteopontin, in most cases the expression of osteopontin rated at [+] (57.1%) and [++] (42.9%). Our study analyzed the relationship between the expression of osteopontin and traditional prognostic markers, such as the tumor grade, size, and lymph node involvement. We found a strong relationship only between the expression of osteopontin and the presence of lymph node metastases (p ≤ 0.0001). 93% of patients for whom the expression of osteopontin was determined at [++] had metastasis to lymph nodes and, for comparison, only 15% of women for whom the expression of osteopontin was rated at [+] showed the presence of metastases in the lymphatic nodes.

Conclusions

There is a correlation between osteopontin expression and the presence of lymph node metastases in TNBC, suggesting that osteopontin plays an important role in the invasiveness of TNBC.

A Case-Control Study of the Association Between the SPP1 Gene SNPs and the Susceptibility to Breast Cancer in Guangxi, China

Secreted phosphoprotein-1 (SPP1) has been reported to be involved in the pathogenesis of breast cancer (BRC), but the influence of SPP1 single nucleotide polymorphisms on the BRC susceptibility has been rarely reported. In this study, we explored the association between rs11730582, rs2853750, and rs35893069 in the SPP1 gene and the BRC susceptibility. We used Snapshot assay to detect SPP1 single nucleotide polymorphisms in 471 BRC patients and 471 controls. The plasma SPP1 level was measured by ELISA. We found that the CC genotype and C allele of rs11730582 were associated with a significantly decreased BRC risk compared with the TT genotype and T allele, respectively [CC vs. TT: odds ratio (OR) = 0.59, 95% CI = 0.37–0.94, P = 0.026; C vs. T: OR = 0.79, 95% CI = 0.65–0.96, P = 0.022]. In addition, BRC patients and controls with the rs11730582 CC genotype had a lower plasma SPP1 level than did BRC patients and controls with TT genotype (P = 0.007 and P = 0.011, respectively). Moreover, the proportions of rs11730582 CC genotype and C allele were decreased in BRC patients with clinical stages I–III compared with those with clinical stage IV (P = 0.012 and P = 0.003, respectively). Besides, the C-G-T haplotype was associated with a significantly decreased BRC risk compared with the T-A-T haplotype (OR = 0.69, 95% CI = 0.52–0.93, P = 0.015). However, there was no significant association between rs2853750 or rs35893069 and the BRC risk. In summary, our study found the association between rs11730582 and the risk of BRC and suggested that rs11730582 may promote the occurrence and development of BRC by regulating SPP1 expression.

Breast Cancer Stem Cells as Drivers of Tumor Chemoresistance, Dormancy and Relapse: New Challenges and Therapeutic Opportunities

Breast cancer is the most frequent cancer among women worldwide. Therapeutic strategies to prevent or treat metastatic disease are still inadequate although great progress has been made in treating early-stage breast cancer. Cancer stem-like cells (CSCs) that are endowed with high plasticity and self-renewal properties have been shown to play a key role in breast cancer development, progression, and metastasis. A subpopulation of CSCs that combines tumor-initiating capacity and a dormant/quiescent/slow cycling status is present throughout the clinical history of breast cancer patients. Dormant/quiescent/slow cycling CSCs are a key component of tumor heterogeneity and they are responsible for chemoresistance, tumor migration, and metastatic dormancy, defined as the ability of CSCs to survive in target organs and generate metastasis up to two decades after diagnosis. Understanding the strategies that are used by CSCs to resist conventional and targeted therapies, to interact with their niche, to escape immune surveillance, and finally to awaken from dormancy is of key importance to prevent and treat metastatic cancer. This review summarizes the current understanding of mechanisms involved in CSCs chemoresistance, dissemination, and metastasis in breast cancer, with a particular focus on dormant cells. Finally, we discuss how advancements in the detection, molecular understanding, and targeting of dormant CSCs will likely open new therapeutic avenues for breast cancer treatment.

Prognostic value of Osteopontin (SPP1) in colorectal carcinoma requires a personalized molecular approach

Stratification of colorectal cancer for better management and tangible clinical outcomes is lacking in clinical practice. To reach this goal, the identification of reliable biomarker(s) is a prerequisite to deliver personalized colorectal cancer theranostics. Osteopontin (SPP1) is a key extracellular matrix protein involved in several pathophysiological processes including cancer progression and metastasis. However, the exact molecular mechanisms regulating its expression, localization, and molecular functions in cancer are still poorly understood. This study was designed to investigate the SPP1 expression profiles in Saudi colorectal cancer patients, and to assess its prognostic value. Hundred thirty-four (134) archival paraffin blocks of colorectal cancer were collected from King Abdulaziz University Hospital, Saudi Arabia. Tissue microarrays were constructed, and automated immunohistochemistry was performed to evaluate SPP1 protein expression patterns in colorectal cancer. About 20% and 23% of our colorectal cancer samples showed high SPP1 cytoplasmic and nuclear expression patterns, respectively. Cytoplasmic SPP1 did not correlate with age, gender, tumor size, and location. However, significant correlations were observed with tumor grade (p = 0.008), tumor invasion (p = 0.01), and distant metastasis (p = 0.04). Kaplan-Meier survival analysis showed a significantly lower recurrence rate in patients with higher SPP1 cytoplasmic expression (p = 0.05). At multivariate analysis, high SPP1 cytoplasmic expression was an independent favorable prognostic marker (p = 0.02). However, nuclear SPP1 expression did not show any prognostic value (p = 0.712). Our results showed a particular SPP1 prognostic relevance that is not in line with most colorectal cancer previous studies that may be attributed to the molecular pathophysiology of our colorectal cancer cohort. Saudi Arabia has both specific genomic makeup and particular environment that could lead to distinctive molecular roots of cancer. SPP1 has several isoforms, tissue localizations and molecular functions, signaling pathways, and downstream molecular functions. Therefore, a more individualized approach for CRC studies and particularly SPP1 prognosis outcomes' assessment is highly recommended toward precision oncology.

A review on the role of M2 macrophages in bladder cancer; pathophysiology and targeting

Tumor-associated macrophages (TAMs) which are often referred to as immunosuppressive cells (M2 macrophage), constitute a subset of tumor microenvironment cells and affect tumor progression in solid tumors. Recently, these cells have gained remarkable importance as therapeutic candidates for solid tumors. In bladder cancer, major studies have focused on evaluating TAMs in response to Bacillus Calmette-Guerin (BCG) therapy. M2 macrophages may directly impact the BCG-induced immune responses against tumor in bladder cancer. They are the main inhibitors of the tumor microenvironment that promotes growth and metastasis of the tumor. However, the clinical significance of M2 macrophages in bladder cancer is controversial. In this review, we will discuss the clinical significance of M2 macrophages in prognosis of bladder cancer as well as worth of their potential targeting in bladder cancer treatment. In the following, we will introduce important factors resulting in M2 macrophage promotion and also experimental therapeutic agents that may cause the inhibition of bladder cancer tumor growth.

Role of the Microenvironment in Regulating Normal and Cancer Stem Cell Activity: Implications for Breast Cancer Progression and Therapy Response

The epithelial cells in an adult woman’s breast tissue are continuously replaced throughout their reproductive life during pregnancy and estrus cycles. Such extensive epithelial cell turnover is governed by the primitive mammary stem cells (MaSCs) that proliferate and differentiate into bipotential and lineage-restricted progenitors that ultimately generate the mature breast epithelial cells. These cellular processes are orchestrated by tightly-regulated paracrine signals and crosstalk between breast epithelial cells and their tissue microenvironment. However, current evidence suggests that alterations to the communication between MaSCs, epithelial progenitors and their microenvironment plays an important role in breast carcinogenesis. In this article, we review the current knowledge regarding the role of the breast tissue microenvironment in regulating the special functions of normal and cancer stem cells. Understanding the crosstalk between MaSCs and their microenvironment will provide new insights into how an altered breast tissue microenvironment could contribute to breast cancer development, progression and therapy response and the implications of this for the development of novel therapeutic strategies to target cancer stem cells.

MiR-181a Promotes Apoptosis and Reduces Cisplatin Resistance by Inhibiting Osteopontin in Cervical Cancer Cells

Objective: In this study, the authors established a cervical cancer cisplatin (DDP) drug-resistant cell line to explore the role of miR-181a in the regulation of osteopontin (OPN) expression and the proliferation, apoptosis, as well as DDP resistance of cervical cancer cells. Materials and Methods: Dual luciferase reporter gene assay was performed to validate the targeted relationship between miR-181a and OPN. The DDP-resistant cell line CaSki/DDP was established to compare the expressions of miR-181a and OPN. The cell proliferation activity was detected by CCK-8 assay. CaSki/DDP cells were divided into miR-NC group and miR-181a mimic group followed by analysis of cell apoptosis by flow cytometry, and the cell proliferation by EdU staining. Results: There was a targeted relationship between miR-181a and OPN mRNA. MiR-181a expression was significantly lower, while OPN mRNA and protein levels were significantly higher in CaSki/DDP cells than that in CaSki cells. Compared with the miR-NC group, OPN mRNA and protein were significantly decreased, cell apoptosis was significantly increased, and cell proliferation ability was significantly attenuated in miR-181a mimic transfection group. Conclusions: The decrease of miR-181a expression and the upregulation of OPN expression are related to the DDP resistance of cervical cancer cells. Overexpression of miR-181a can inhibit the expression of OPN, induce cell apoptosis cells, restrain cell proliferation, and reduce DDP resistance in cervical cancer cells.

Osteopontin Promotes Colorectal Cancer Cell Invasion and the Stem Cell-Like Properties through the PI3K-AKT-GSK/3β-β/Catenin Pathway

BACKGROUND Osteopontin (OPN) is a molecule expressed in numerous cancers including colorectal cancer (CRC) that correlates disease progression. The interaction of OPN that promotes CRC cell migration, invasion, and cancer stem-like cells (CSCs) have not been elucidated. Hence, we aimed to investigate the mechanisms that might be involved. MATERIAL AND METHODS Expression of OPN in tumor tissues derived from patients was monitored with real-time quantitative polymerase chain reaction and western blot. Wound healing and Transwell assay were used to test the differences in migration and invasion in an OPN enriched environment and OPN knockdown condition. Aldehyde dehydrogenase 1 (ALDH1) positive stem cells were isolated using fluorescence-activated cell sorting (FACS) following the protocol of the ALDEFLUOR™ kit. The expression of protein participation in the PI3K-Akt-GSK/3ß-ß/catenin pathway was detected by western blot. RESULTS OPN exhibited increased levels in CRC tumor tissue compared with non-tumor normal tissue and the high level of which correlated with lymphatic metastasis and late TNM stage. Additional rhOPN co-cultured low-expression CRC cells demonstrated more aggressive capability of proliferation, migration, and invasion. For knockdown of OPN in high-expression CRC cells, the bioactivities of proliferation, migration, and invasion were significantly inhibited. Interestingly, the percentage of ALDH1 labeled stem cells was dramatically decreased by OPN inhibition. The phosphorylation of PI3K-Akt-GSK/3ß-ß/catenin pathway was involved in the OPN signaling. Furthermore, Ly294002, a specific PI3K inhibitor, can reverse the promotion of bioactivities and stem cell proportion among rhOPN treated CRC cells. CONCLUSIONS OPN promoted cell proliferation, migration, and invasion, and was accompanied by upregulation of ALDH1-positive CSC in CRC through activation of PI3K-Akt-GSK/3ß-ß/catenin pathway.

Effects of Ascorbic Acid on Osteopontin Expression and Axonal Myelination in the Developing Cerebellum of Lead-Exposed Rat Pups

Osteopontin (OPN) is a multi-functional protein that binds to integrin and calcium-binding phosphoprotein. OPN is required for normal neuronal development and its axonal myelination. We studied the combined effect of lead (Pb) and ascorbic acid treatment on OPN expression in the developing cerebellum. We randomly divided pregnant female rats into three groups: control, Pb (lead acetate, 0.3%, drinking water), and Pb plus ascorbic acid (PA; ascorbic acid, 100 mg/kg, oral intubation) groups. The blood level of Pb was significantly increased, while ascorbic acid reduced Pb levels in the dams and pups. At postnatal day (PND) 21, results from Nissl staining and OPN immunohistochemistry demonstrated that OPN was detected in the Purkinje cell layer in the cerebellum. Ascorbic acid treatment mitigated Pb exposure-induced reduction in the number of intact Purkinje cells and OPN immunoreactive Purkinje cells in the cerebellum of pups. In addition, Pb-induced reduction in the number of oligodendrocytes and myelin-associated glycoprotein is associated with the malformation of the myelin sheath. Ascorbic acid provided protection from Pb-induced impairments. Pb-induced structural deficits in the cerebellum resulted in functional deterioration observed during locomotive tests (bar holding test and wire mesh ascending test), while ascorbic acid ameliorated these harmful effects. Present results suggest that the change of OPN is associated with myelination in the developing cerebellum. The results also demonstrated that exposure to Pb is harmful, while ascorbic acid treatment is beneficial.

Tissue-engineered nanoclay-based 3D in vitro breast cancer model for studying breast cancer metastasis to bone

Breast cancer (BrCa) preferentially spreads to bone and colonises within the bone marrow to cause bone metastases. To improve the outcome of patients with BrCa bone metastasis, we need to understand better the mechanisms underlying bone metastasis. Researchers have relied heavily upon in vivo xenografts due to limited availability of human bone metastasis samples. A significant limitation of these is that they do not have a human bone microenvironment. To address this issue, we have developed a nanoclay-based 3D in vitro model of BrCa bone metastasis using human mesenchymal stem cells (MSCs) and human BrCa cells mimicking late stage of BrCa pathogenesis at the metastatic site. This 3D model can provide a microenvironment suitable for cell-cell and cell-matrix interactions whilst retaining the behaviour of BrCa cells with different metastasis potential (i.e., highly metastatic MDA-MB-231 and low metastatic MCF-7) as shown by the production of alkaline phosphatase and matrix metalloproteinase-9. The sequential culture of MSCs with MCF-7 exhibited 3D tumouroids formation and also occurrence of mesenchymal to epithelial transition of cancer metastasis as evidenced by gene expression and immunocytochemistry. The unique and distinct behaviour of highly metastatic MDA-MB-231 and the low metastatic MCF-7 was observed at the bone metastasis site. The changes to migratory capabilities and invasiveness in MDA-MB-231 in comparison with tumour growth with MCF-7 was observed. Together, a novel bone-mimetic 3D in vitro BrCa model has been developed that could be used to study mechanisms governing the later stage of cancer pathogenesis in bone.

Breast cancer stem cells: Biology and therapeutic implications

Breast cancer remains to be a dreadful disease even with several advancements in radiation and chemotherapies, owing to the drug resistance and tumor relapse caused by breast cancer stem cells. Cancer stem cells are a minute population of cells of solid tumors which show self-renewal and differentiation properties as well as tumorigenic potential. Several signaling pathways including Notch, Hippo, Wnt and Hedgehog and tumor-stroma exchanges play a critical role in the self-renewal and differentiation of cancer stem cells in breast cancer. Cancer stem cells can grow anchorage-independent manner so they disseminate to different parts of the body to form secondary tumors. Cancer stem cells promote angiogenesis by dedifferentiating to endothelial cells as well as secreting proangiogenic and angiogenic factors. Moreover, multidrug resistance genes and drug efflux transporters expressed in breast cancer stem cells confer resistance to various conventional chemotherapeutic drugs. Indeed, these therapies are recognised to enhance the percent of cancer stem cell population in tumors leading to cancer relapse with increased aggressiveness. Hence, devising the therapeutic interventions to target cancer stem cells would be useful in increasing patients' survival rates. In addition, targeting the self-renewal pathways and tumor-stromal cross-talk helps in eradicating this population. Reversal of the cancer stem cell-mediated drug resistance would increase the sensitivity to various conventional drugs for the effective management of breast cancer. In this review, we have discussed the cancer stem cell origin and their involvement in angiogenesis, metastasis and therapy-resistance. We have also summarized different therapeutic approaches to eradicate the same for the successful treatment of breast cancer.

Secretome within the bone marrow microenvironment: A basis for mesenchymal stem cell treatment and role in cancer dormancy

The secretome produced by cells within the bone marrow is significant to homeostasis. The bone marrow, a well-studied organ, has multiple niches with distinct roles for supporting stem cell functions. Thus, an understanding of mediators involved in the regulation of stem cells could serve as a model for clinical problems and solutions such as tissue repair and regeneration. The exosome secretome of bone marrow stem cells is a developing area of research with respect to the regenerative potential by bone marrow cell, particularly the mesenchymal stem cells. The bone marrow niche regulates endogenous processes such as hematopoiesis but could also support the survival of tumors such as facilitating the cancer stem cells to exist in dormancy for decades. The bone marrow-derived secretome will be critical to future development of therapeutic strategies for oncologic diseases, in addition to regenerative medicine. This article discusses the importance for parallel studies to determine how the same secretome may compromise safety during the use of stem cells in regenerative medicine.