TGF-β2: A Novel Target of CD44-Promoted Breast Cancer Invasion

High Throughput Bioprinting Using Decellularized Adipose Tissue-Based Hydrogels for 3D Breast Cancer Modeling

3D bioprinting allows rapid automated fabrication and can be applied for high throughput generation of biomimetic constructs for in vitro drug screening. Decellularized extracellular matrix (dECM) hydrogel is a popular biomaterial choice for tissue engineering and studying carcinogenesis as a tumor microenvironmental mimetic. This study proposes a method for high throughput bioprinting with decellularized adipose tissue (DAT) based hydrogels for 3D breast cancer modeling. A comparative analysis of decellularization protocol using detergent-based and detergent-free decellularization methods for caprine-origin adipose tissue is performed, and the efficacy of dECM hydrogel for 3D cancer modeling is assessed. Histological, biochemical, morphological, and biological characterization and analysis showcase the cytocompatibility of DAT hydrogel. The rheological property of DAT hydrogel and printing process optimization is assessed to select a bioprinting window to attain 3D breast cancer models. The bioprinted tissues are characterized for cellular viability and tumor cell-matrix interactions. Additionally, an approach for breast cancer modeling is shown by performing rapid high throughput bioprinting in a 96-well plate format, and in vitro drug screening using 5-fluorouracil is performed on 3D bioprinted microtumors. The results of this study suggest that high throughput bioprinting of cancer models can potentially have downstream clinical applications like multi-drug screening platforms and personalized disease models.

Assessment and process optimization of high throughput biofabrication of immunocompetent breast cancer model for drug screening applications

Recent advancements in 3D cancer modeling have significantly enhanced our ability to delve into the intricacies of carcinogenesis. Despite the pharmaceutical industry's substantial investment of both capital and time in the drug screening and development pipeline, a concerning trend persists: drug candidates screened on conventional cancer models exhibit a dismal success rate in clinical trials. One pivotal factor contributing to this discrepancy is the absence of drug testing on pathophysiologically biomimetic 3D cancer models during pre-clinical stages. Unfortunately, current manual methods of 3D cancer modeling, such as spheroids and organoids, suffer from limitations in reproducibility and scalability. In our study, we have meticulously developed 3D bioprinted breast cancer model utilizing decellularized adipose tissue-based hydrogel obtained via a detergent-free decellularization method. Our innovative printing techniques allows for rapid, high-throughput fabrication of 3D cancer models in a 96-well plate format, demonstrating unmatched scalability and reproducibility. Moreover, we have conducted extensive validation, showcasing the efficacy of our platform through drug screening assays involving two potent anti-cancer drugs, 5-Fluorouracil and PRIMA-1Met. Notably, our platform facilitates effortless imaging and gene expression analysis, streamlining the evaluation process. In a bid to enhance the relevance of our cancer model, we have introduced a heterogeneous cell population into the DAT-based bioink. Through meticulous optimization and characterization, we have successfully developed a biomimetic immunocompetent breast cancer model, complete with microenvironmental cues and diverse cell populations. This breakthrough paves the way for rapid multiplex drug screening and the development of personalized cancer models, marking a paradigm shift in cancer research and pharmaceutical development.

ITGB1BP1, a Novel Transcriptional Target of CD44-Downstream Signaling Promoting Cancer Cell Invasion

Breast cancer (BC) is the most common malignancy worldwide and has a poor prognosis, because it begins in the breast and disseminates to lymph nodes and distant organs. While invading, BC cells acquire aggressive characteristics from the tumor microenvironment through several mechanisms. Thus, understanding the mechanisms underlying the process of BC cell invasion can pave the way towards the development of targeted therapeutics focused on metastasis. We have previously reported that the activation of CD44 receptor with its major ligand hyaluronan (HA) promotes BC metastasis to the liver in vivo. Next, a gene expression profiling microarray analysis was conducted to identify and validate CD44-downstream transcriptional targets mediating its pro-metastatic function from RNA samples collected from Tet CD44-induced versus control MCF7-B5 cells. We have already validated a number of novel CD44-target genes and published their underlying signaling pathways in promoting BC cell invasion. From the same microarray analysis, Integrin subunit beta 1 binding protein 1 (ITGB1BP1) was also identified as a potential CD44-target gene that was upregulated (2-fold) upon HA activation of CD44. This report will review the lines of evidence collected from the literature to support our hypothesis, and further discuss the possible mechanisms linking HA activation of CD44 to its novel potential transcriptional target ITGB1BP1.

SIRT1, a novel transcriptional downstream target of CD44, linking its deacetylase activity to tumor cell invasion/metastasis

Our tetracycline-off-inducible CD44 expression system previously established in mouse model, revealed that activation of CD44 with its major ligand hyaluronan (HA) promoted breast cancer (BC) metastasis to the liver. To identify the mechanisms that underpin CD44-promoted BC cell invasion, microarray gene expression profiling using RNA samples from (Tet)-Off-regulated expression system of CD44s in MCF7 cells, revealed a set of upregulated genes including, nuclear sirtuin-1 (SIRT1 also known as NAD-dependent deacetylase), an enzyme that requires NAD⁺ as a cofactor to deacetylate several histones and transcription factors. It stimulates various oncogenic pathways promoting tumorigenesis. This data suggests that SIRT1 is a potential novel transcriptional target of CD44-downstream signaling that promote BC cell invasion/metastasis. This review will discuss the evidence supporting this hypothesis as well as the mechanisms linking SIRT1 to cell proliferation and invasion.

Recent advances in photothermal therapy-based multifunctional nanoplatforms for breast cancer

Breast cancer (BC) is one of the most common cancers in women worldwide; however, the successful treatment of BC, especially triple-negative breast cancer (TNBC), remains a significant clinical challenge. Recently, photothermal therapy (PTT), which involves the generation of heat under irradiation to achieve photothermal ablation of BC with minimal invasiveness and outstanding spatial–temporal selectivity, has been demonstrated as a novel therapy that can overcome the drawbacks of chemotherapy or surgery. Significantly, when combining PTT with chemotherapy and/or photodynamic therapy, an enhanced synergistic therapeutic effect can be achieved in both primary and metastatic BC tumors. Thus, this review discusses the recent developments in nanotechnology-based photothermal therapy for the treatment of BC and its metastasis to provide potential strategies for future BC treatment.

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.

Targeting Cell Death Mechanism Specifically in Triple Negative Breast Cancer Cell Lines

Triple negative breast cancer (TNBC) is currently associated with a lack of treatment options. Arsenic derivatives have shown antitumoral activity both in vitro and in vivo; however, their mode of action is not completely understood. In this work we evaluate the response to arsenate of the double positive MCF-7 breast cancer cell line as well as of two different TNBC cell lines, Hs578T and MDA-MB-231. Multimodal experiments were conducted to this end, using functional assays and microarrays. Arsenate was found to induce cytoskeletal alteration, autophagy and apoptosis in TNBC cells, and moderate effects in MCF-7 cells. Gene expression analysis showed that the TNBC cell lines’ response to arsenate was more prominent in the G2M checkpoint, autophagy and apoptosis compared to the Human Mammary Epithelial Cells (HMEC) and MCF-7 cell lines. We confirmed the downregulation of anti-apoptotic genes (MCL1, BCL2, TGFβ1 and CCND1) by qRT-PCR, and on the protein level, for TGFβ2, by ELISA. Insight into the mode of action of arsenate in TNBC cell lines it is provided, and we concluded that TNBC and non-TNBC cell lines reacted differently to arsenate treatment in this particular experimental setup. We suggest the future research of arsenate as a treatment strategy against TNBC.

SNX5 suppresses clear cell renal cell carcinoma progression by inducing CD44 internalization and epithelial-to-mesenchymal transition

Aberrant expression of SNX5 can contribute to tumorigenesis, invasion, and metastasis of several human cancers. However, the clinicopathological and biological significance of SNX5 in clear cell renal cell carcinoma (ccRCC) remain unclear. In this study, we found that SNX5 expression was downregulated and negatively correlated with tumor size, American Joint Committee on Cancer stage, tumor thrombus of inferior vena cava, and poor prognosis in human ccRCC. Ectopic expression of SNX5 inhibited ccRCC cell proliferation and metastasis, whereas knockdown of SNX5 increased these activities both in vitro and in vivo. Mechanistically, overexpression of SNX5 blocked internalization and intracellular trafficking of CD44 in ccRCC cells. Knockdown of SNX5 was associated with epithelial-to-mesenchymal transition (EMT) in ccRCC cells. Overexpression of SNX5 inhibited TGF-β-induced migration, invasion, and EMT in ccRCC cells. KLF9 directly bound to the SNX5 promoter and increased SNX5 transcription. Moreover, we found that the combination of SNX5 and CD44 or E-cadherin or KLF9 was a more powerful predictor of poor prognosis than either parameter alone. Collectively, our data reveal a mechanism that KLF9-mediated SNX5 expression was associated with poor prognosis via trafficking of CD44 and promoting EMT in ccRCC. SNX5 may be a potential prognostic biomarker and therapeutic target for patients with ccRCC.

SOD2, a Potential Transcriptional Target Underpinning CD44-Promoted Breast Cancer Progression

CD44, a cell-adhesion molecule has a dual role in tumor growth and progression; it acts as a tumor suppressor as well as a tumor promoter. In our previous work, we developed a tetracycline-off regulated expression of CD44's gene in the breast cancer (BC) cell line MCF-7 (B5 clone). Using cDNA oligo gene expression microarray, we identified SOD2 (superoxide dismutase 2) as a potential CD44-downstream transcriptional target involved in BC metastasis. SOD2 gene belongs to the family of iron/manganese superoxide dismutase family and encodes a mitochondrial protein. SOD2 plays a role in cell proliferation and cell invasion via activation of different signaling pathways regulating angiogenic abilities of breast tumor cells. This review will focus on the findings supporting the underlying mechanisms associated with the oncogenic potential of SOD2 in the onset and progression of cancer, especially in BC and the potential clinical relevance of its various inhibitors.

The differentiation state of the Schwann cell progenitor drives phenotypic variation between two contagious cancers

Contagious cancers are a rare pathogenic phenomenon in which cancer cells gain the ability to spread between genetically distinct hosts. Nine examples have been identified across marine bivalves, dogs and Tasmanian devils, but the Tasmanian devil is the only mammalian species known to have given rise to two distinct lineages of contagious cancer, termed Devil Facial Tumour 1 (DFT1) and 2 (DFT2). Remarkably, DFT1 and DFT2 arose independently from the same cell type, a Schwann cell, and while their ultra-structural features are highly similar they exhibit variation in their mutational signatures and infection dynamics. As such, DFT1 and DFT2 provide a unique framework for investigating how a common progenitor cell can give rise to distinct contagious cancers. Using a proteomics approach, we show that DFT1 and DFT2 are derived from Schwann cells in different differentiation states, with DFT2 carrying a molecular signature of a less well differentiated Schwann cell. Under inflammatory signals DFT1 and DFT2 have different gene expression profiles, most notably involving Schwann cell markers of differentiation, reflecting the influence of their distinct origins. Further, DFT2 cells express immune cell markers typically expressed during nerve repair, consistent with an ability to manipulate their extracellular environment, facilitating the cell’s ability to transmit between individuals. The emergence of two contagious cancers in the Tasmanian devil suggests that the inherent plasticity of Schwann cells confers a vulnerability to the formation of contagious cancers.

Cancer can be an infectious pathogen, with nine known cases, infecting bivalves, dogs and two independent tumours circulating in the endangered Tasmanian devil. These cancers, known as Devil Facial Tumour 1 (DFT1) and Devil Facial Tumour 2 (DFT2), spread through the wild population much like parasites, moving between genetically distinct hosts during social biting behaviours and persisting in the population. As DFT1 and DFT2 are independent contagious cancers that arose from the same cell type, a Schwann cell, they provide a unique model system for studying the emergence of phenotypic variation in cancers derived from a single progenitor cell. In this study, we have shown that these two remarkably similar tumours have emerged from Schwann cells in different differentiation states. The differentiation state of the progenitor has altered the characteristics of each tumour, resulting in different responses to external signals. This work demonstrates that the cellular origin of infection can direct the phenotype of a contagious cancer and how it responds to signals from the host environment. Further, the plasticity of Schwann cells may make these cells more prone to forming contagious cancers, raising the possibility that further parasitic cancers could emerge from this cell type.

A cytokine in turmoil: Transforming growth factor beta in cancer

Cancer remains one of the debilitating health threats to mankind in view of its incurable nature. Many factors are complicit in the initiation, progression and establishment of cancers. Early detection of cancer is the only window of hope that allows for appreciable management and possible limited survival. However, understanding of cancer biology and knowledge of the key factors that interplay at multi-level in the initiation and progression of cancer may hold possible avenues for cancer treatment and management. In particular, dysregulation of growth factor signaling such as that of transforming growth factor beta (TGF-β) and its downstream mediators play key roles in various cancer subtypes. Expanded understanding of the context/cell type-dependent roles of TGF-β and its downstream signaling mediators in cancer may provide leads for cancer pharmacotherapy. Reliable information contained in original articles, reviews, mini-reviews and expert opinions on TGF-β, cancer and the specific roles of TGF-β signaling in various cancer subtypes were retrieved from major scientific data bases including PubMed, Scopus, Medline, Web of Science core collections just to mention but a sample by using the following search terms: TGF-β in cancer, TGF-β and colorectal cancer, TGF-β and brain cancer, TGF-β in cancer initiation, TGF-β and cell proliferation, TGF-β and cell invasion, and TGF-β-based cancer therapy. Retrieved information and reports were carefully examined, contextualized and synchronized into a coherent scientific content to highlight the multiple roles of TGF-β signaling in normal and cancerous cells. From a conceptual standpoint, development of pharmacologically active agents that exert non-specific inhibitory effects on TGF-β signaling on various cell types will undoubtedly lead to a plethora of serious side effects in view of the multi-functionality and pleiotropic nature of TGF-β. Such non-specific targeting of TGF-β could derail any beneficial therapeutic intention associated with TGF-β-based therapy. However, development of pharmacologically active agents designed specifically to target TGF-β signaling in cancer cells may improve cancer pharmacotherapy. Similarly, specific targeting of downstream mediators of TGF-β such as TGF-β type 1 and II receptors (TβRI and TβRII), receptor-mediated Smads, mitogen activated protein kinase (MAPK) and importing proteins in cancer cells may be crucial for cancer pharmacotherapy.

KYNU, a novel potential target that underpins CD44-promoted breast tumour cell invasion

Using a validated tetracycline‐off‐inducible CD44 expression system in mouse model, we have previously demonstrated that the hyaluronan (HA) receptor CD44 promotes breast cancer (BC) metastasis to the liver. To unravel the mechanisms that underpin CD44‐promoted BC cell invasion, RNA samples were isolated from two cell models: (a) a tetracycline (Tet)‐Off‐regulated expression system of the CD44s in MCF‐7 cells and; (b) as a complementary approach, the highly metastatic BC cells, MDA‐MB‐231, were cultured in the presence and absence of 50 µg/mL of HA. Kynureninase (KYNU), identified by Microarray analysis, was up‐regulated by 3‐fold upon induction and activation of CD44 by HA; this finding suggests that KYNU is a potential novel transcriptional target of CD44‐downtstream signalling. KYNU is a pyridoxal phosphate (PLP) dependent enzyme involved in the biosynthesis of NAD cofactors from tryptophan that has been associated with the onset and development of BC. This review will attempt to identify and discuss the findings supporting this hypothesis and the mechanisms linking KYNU cell invasion via CD44.

Proteolytic Processing of CD44 and Its Implications in Cancer

CD44 is a transmembrane glycoprotein expressed in several healthy and tumor tissues. Modifications in its structure contribute differently to the activity of this molecule. One modification that has provoked interest is the consecutive cleavage of the CD44 extracellular ectodomain by enzymes that belong mainly to the family of metalloproteases. This process releases biologically active substrates, via alternative splice forms of CD44, that generate CD44v3 or v6 isoforms which participate in the transcriptional regulation of genes and proteins associated to signaling pathways involved in the development of cancer. These include the protooncogene tyrosine-protein kinase Src (c-Src)/signal transducer and activator of transcription 3 (STAT3), the epithelial growth factor receptor, the estrogen receptor, Wnt/βcatenin, or Hippo signaling pathways all of which are associated to cell proliferation, differentiation, or cancer progression. Whereas CD44 still remains as a very useful prognostic cell marker in different pathologies, the main topic is that the generation of CD44 intracellular fragments assists the regulation of transcriptional proteins involved in the cell cycle, cell metabolism, and most importantly, the regulation of some stem cell-associated markers.

Distinct phenotypes of cancer cells on tissue matrix gel

BACKGROUND

Breast cancer cells invading the connective tissues outside the mammary lobule or duct immerse in a reservoir of extracellular matrix (ECM) that is structurally and biochemically distinct from that of their site of origin. The ECM is a spatial network of matrix proteins, which not only provide physical support but also serve as bioactive ligands to the cells. It becomes evident that the dimensional, mechanical, structural, and biochemical properties of ECM are all essential mediators of many cellular functions. To better understand breast cancer development and cancer cell biology in native tissue environment, various tissue-mimicking culture models such as hydrogel have been developed. Collagen I (Col I) and Matrigel are the most common hydrogels used in cancer research and have opened opportunities for addressing biological questions beyond the two-dimensional (2D) cell cultures. Yet, it remains unclear whether these broadly used hydrogels can recapitulate the environmental properties of tissue ECM, and whether breast cancer cells grown on CoI I or Matrigel display similar phenotypes as they would on their native ECM.

METHODS

We investigated mammary epithelial cell phenotypes and metabolic profiles on animal breast ECM-derived tissue matrix gel (TMG), Col I, and Matrigel. Atomic force microscopy (AFM), fluorescence microscopy, acini formation assay, differentiation experiments, spatial migration/invasion assays, proliferation assay, and nuclear magnetic resonance (NMR) spectroscopy were used to examine biological phenotypes and metabolic changes. Student's t test was applied for statistical analyses.

RESULTS

Our data showed that under a similar physiological stiffness, the three types of hydrogels exhibited distinct microstructures. Breast cancer cells grown on TMG displayed quite different morphologies, surface receptor expression, differentiation status, migration and invasion, and metabolic profiles compared to those cultured on Col I and Matrigel. Depleting lactate produced by glycolytic metabolism of cancer cells abolished the cell proliferation promoted by the non-tissue-specific hydrogel.

CONCLUSION

The full ECM protein-based hydrogel system may serve as a biologically relevant model system to study tissue- and disease-specific pathological questions. This work provides insights into tissue matrix regulation of cancer cell biomarker expression and identification of novel therapeutic targets for the treatment of human cancers based on tissue-specific disease modeling.

Anticancer and Apoptogenic Effect of Graviola and Low-Dose Radiation in Tumor Xenograft in Mice

Background: Annona muricata (graviola) has been claimed for its potential against various diseases including cancer. Objective: The present study aimed to investigate the anticancer effect of graviola extract on Ehrlich solid tumor (EST) mice along with or without a low dose of γ radiation (LDR). Methods: Mice were treated with graviola 50 mg/kg body weight orally for 30 days after EST induction and exposed to γ-ray (2 Gy/week for 3 weeks). Cell cycle, CD44, TGF-β, Bcl-2, and annexin V were determined in tumor tissue. Results: The result obtained showed a significant decrease (P < .05) of tumor size in 28 graviola-treated EST-bearing mice group (EG) or graviola-treated and irradiated EST-30-bearing mice (EGR) groups versus the EST group. The large number of cells in the sub-G0/G1 population and low cell number at S and M phases signify tumor cell apoptosis and inhibition of cell division in EG or EGR groups. Additionally, significant increases in the expression of CD44 and TGF-β were recorded in EST mice as compared with EG or EGR mice. Furthermore, EST mice exhibited a decrease in the apoptotic marker annexin v and increase in antiapoptotic Bcl-2 compared with EG and EGR mice. Conclusion: It could be suggested that graviola exerts its antitumor effect throughout the regulation of the tumor cell cycle as well as inducing apoptotic signals. The combined treatment of graviola and LDR augments their effect on tumor proliferation.

CD44 mediates stem cell mobilization to damaged lung via its novel transcriptional targets, Cortactin and Survivin

Beyond their role in bone and lung homeostasis, mesenchymal stem cells (MSCs) are becoming popular in cell therapy. Various insults may disrupt the repair mechanisms involving MSCs. One such insult is smoking, which is a major risk factor for osteoporosis and respiratory diseases. Upon cigarette smoke-induced damage, a series of reparatory mechanisms ensue; one such mechanism involves Glycosaminoglycans (GAG). One of these GAGs, namely hyaluronic acid (HA), serves as a potential therapeutic target in lung injury. However, much of its mechanisms of action through its major receptor CD44 remains unexplored. Our previous studies have identified and functionally validated that both cortactin (CTTN: marker of motility) and Survivin (BIRC5: required for cell survival) act as novel HA/CD44-downstream transcriptional targets underpinning cell motility. Here, human MSCs were treated with "Water-pipe" smoke to investigate the effects of cigarette smoke condensate (CSC) on these HA-CD44 novel signaling pathways. Our results show that CSC decreased the expression of both CD44 and its downstream targets CTTN and BIRC5 in MSCs, and that HA reversed these effects. Interestingly, CSC inhibited migration and invasion of MSCs upon CD44-targeted RNAi treatment. This shows the importance of CD44-HA/CTTN and CD44-HA/BIRC5 signaling pathways in MSC motility, and further suggests that these signaling pathways may provide a novel mechanism implicated in migration of MSCs during repair of lung tissue injury. These findings suggest that one should use caution before utilizing MSC from donors with history of smoking, and further pave the way towards the development of targeted therapeutic approaches against CD44-associated diseases.

OSM-induced CD44 contributes to breast cancer metastatic potential through cell detachment but not epithelial-mesenchymal transition

Background

Hormone receptor status in human breast cancer cells is a strong indicator of the aggressiveness of a tumor. Triple negative breast cancers (TNBC) are aggressive, difficult to treat, and contribute to high incidences of metastasis by possessing characteristics such as increased tumor cell migration and a large presence of the transmembrane protein, cluster of differentiation 44 (CD44) on the cell membrane. Estrogen receptor-positive (ER+) cells are less aggressive and do not migrate until undergoing an epithelial-mesenchymal transition (EMT).

Methods

The relationship between EMT and CD44 during metastatic events is assessed by observing changes in EMT markers, tumor cell detachment, and migration following cytokine treatment on both parental and CD44 knockdown human breast tumor cells.

Results

ER+ T47D and MCF-7 human breast cancer cells treated with OSM demonstrate increased CD44 expression and CD44 cleavage. Conversely, ER- MDA-MB-231 human breast cancer cells do not show a change in CD44 expression nor undergo EMT in the presence of OSM. In ER+ cells, knockdown expression of CD44 by shRNA did not prevent EMT but did change metastatic processes such as cellular detachment and migration. OSM-induced migration was decreased in both ER+ and ER- cells with shCD44 cells compared to control cells, while the promotion of tumor cell detachment by OSM was decreased in ER+ MCF7-shCD44 cells, as compared to control cells. Interestingly, OSM-induced detachment in ER- MDA-MB-231-shCD44 cells that normally don't detach at significant rates.

Conclusion

OSM promotes both EMT and tumor cell detachment in ER+ breast cancer cells. Yet, CD44 knockdown did not affect OSM-induced EMT in these cells, while independently decreasing OSM-induced cell detachment. These results suggest that regulation of CD44 by OSM is important for at least part of the metastatic cascade in ER+ breast cancer.

Osteopontin controls immunosuppression in the tumor microenvironment

Cancer cells evade the immune system through a variety of different mechanisms, including the inhibition of antitumor effector T cells via checkpoint ligand-receptor interaction. Moreover, studies have shown that blocking these checkpoint pathways can reinvigorate the antitumor immunity, thereby prompting the development of numerous checkpoint immunotherapies, several of which are now being approved to treat multiple types of cancer. However, only a fraction of patients achieves promising long-term outcomes in response to checkpoint inhibition, suggesting the existence of additional unknown tumor-induced immunosuppressive pathways. In this issue of the JCI, Klement and colleagues describe an additional pathway of T cell inhibition in cancer. Specifically, the authors demonstrate that downregulation of IRF8, a molecular determinant of apoptotic resistance, in tumor cells aborts repression of osteopontin, which in turn binds to its physiological receptor CD44 on activated T cells and suppresses their activation. These results suggest that osteopontin may act as another immune checkpoint and may serve as a target to expand the number of patients who respond to immune checkpoint inhibitor therapy.

Novel CD44-downstream signaling pathways mediating breast tumor invasion

CD44, also known as homing cell adhesion molecule is a multi-structural cell molecule involved in cell-cell and cell-extracellular matrix communications. CD44 regulates a number of central signaling pathways, including PI3K/AKT, Rho GTPases and the Ras-MAPK pathways, but also acts as a growth/arrest sensor, and inhibitor of angiogenesis and invasion, in response to signals from the microenvironment. The function of CD44 has been very controversial since it acts as both, a suppressor and a promoter of tumor growth and progression. To address this discrepancy, we have previously established CD44-inducible system both in vitro and in vivo. Next, using microarray analysis, we have identified and validated Survivin, Cortactin and TGF-β2 as novel CD44-downstream target genes, and characterized their signaling pathways underpinning CD44-promoted breast cancer (BC) cell invasion. This report aims to update the literature by adding and discussing the impact of these novel three signaling pathways to better understand the CD44-signaling pathways involved in BC tumor cell invasion.

A correlation study of the expression of HA-CD44st and HER-2 in breast cancer

Background

This study investigated the effect of hyaluronic acid (HA)-CD44st on the invasive ability of human breast cancer MCF-7 cells and the correlation between the expression of CD44st and human epidermal growth factor receptor-2 (HER-2) in postoperative breast cancer patients.

Materials and methods

MCF-7 cells transfected with the eukaryotic expression vector pcDNA3.1-CD44st (MCF/CD44st) were used to examine the effect of the activation of the HA-CD44st-transforming growth factor β (TGFβ)-phosphatidylinositol-3-kinase (PI3K) signaling pathway on the invasive ability of MCF-7 cells. The expression of proteins related to this signaling pathway was assessed by flow cytometry, reverse transcription-polymerase chain reaction, and Western blotting, and the role of AP-1 in the pathway was investigated by electrophoretic mobility shift assay. The effect of pathway activation on the invasion of MCF-7 cells was assessed by Transwell assay, and CD44 expression in breast cancer tissue was detected by immunohistochemistry. Quantitative reverse transcription-polymerase chain reaction was used to detect the expression of CD44st and HER-2 in breast cancer tissue and their correlation was investigated.

Results

HA significantly upregulated HER-2 and TGFβ in MCF-7/CD44st cells, increased p-AKT expression and AP-1 activity, and promoted the invasive ability of tumor cells. CD44st mRNA expression had significant difference between breast cancer tissues and adjacent normal tissues (P < 0.05), and high expression of CD44st mRNA was closely correlated with HER-2 expression in breast cancer tissues.

Conclusion

Binding of HA to the CD44st receptor may regulate the invasiveness of MCF-7 cells through the CD44st/TGFβ/PI3K/AP-1 signaling pathway with increased expression of TGFβ and HER-2. The expression of CD44st mRNA is correlated with HER-2 expression in postoperative breast cancer patients.

The biology and role of CD44 in cancer progression: therapeutic implications

CD44, a non-kinase transmembrane glycoprotein, is overexpressed in several cell types including cancer stem cells and frequently shows alternative spliced variants that are thought to play a role in cancer development and progression. Hyaluronan, the main ligand for CD44, binds to and activates CD44 resulting in activation of cell signaling pathways that induces cell proliferation, increases cell survival, modulates cytoskeletal changes, and enhances cellular motility. The different functional roles of CD44 standard (CD44s) and specific CD44 variant (CD44v) isoforms are not fully understood. CD44v contain additional peptide motifs that can interact with and sequester growth factors and cytokines at the cell surface thereby functioning as coreceptors to facilitate cell signaling. Moreover, CD44v were expressed in metastasized tumors, whereas switching between CD44v and CD44s may play a role in regulating epithelial to mesenchymal transition (EMT) and in the adaptive plasticity of cancer cells. Here, we review current data on the structural and functional properties of CD44, the known roles for CD44 in tumorigencity, the regulation of CD44 expression, and the potential for targeting CD44 for cancer therapy.

CD146, a novel target of CD44-signaling, suppresses breast tumor cell invasion

Background

We have previously validated three novel CD44-downstream positively regulated transcriptional targets, including Cortactin, Survivin and TGF-β2, and further characterized the players underlying their separate signaling pathways. In the present study, we identified CD146 as a potential novel target, negatively regulated by CD44. While the exact function of CD146 in breast cancer (BC) is not completely understood, substantial evidence from our work and others support the hypothesis that CD146 is a suppressor of breast tumor progression.

Methods

Therefore, using molecular and pharmacological approaches both in vitro and in breast tissues of human samples, the present study validated CD146 as a novel target of CD44-signaling suppressed during BC progression.

Results

Our results revealed that CD44 activation could cause a substantial decrease of CD146 expression with an equally notable converse effect upon CD44-siRNA inhibition. More interestingly, activation of CD44 decreased cellular CD146 and increased soluble CD146 through CD44-dependent activation of MMP.

Conclusion

Here, we provide a possible mechanism by which CD146 suppresses BC progression as a target of CD44-downstream signaling, regulating neovascularization and cancer cell motility.

Tartrate-resistant acid phosphatase (TRAP/ACP5) promotes metastasis-related properties via TGFβ2/TβR and CD44 in MDA-MB-231 breast cancer cells

BACKGROUND

Tartrate-resistant acid phosphatase (TRAP/ACP5), a metalloenzyme that is characteristic for its expression in activated osteoclasts and in macrophages, has recently gained considerable focus as a driver of metastasis and was associated with clinically relevant parameters of cancer progression and cancer aggressiveness.

METHODS

MDA-MB-231 breast cancer cells with different TRAP expression levels (overexpression and knockdown) were generated and characterized for protein expression and activity levels. Functional cell experiments, such as proliferation, migration and invasion assays were performed as well as global phosphoproteomic and proteomic analysis was conducted to connect molecular perturbations to the phenotypic changes.

RESULTS

We identified an association between metastasis-related properties of TRAP-overexpressing MDA-MB-231 breast cancer cells and a TRAP-dependent regulation of Transforming growth factor (TGFβ) pathway proteins and Cluster of differentiation 44 (CD44). Overexpression of TRAP increased anchorage-independent and anchorage-dependent cell growth and proliferation, induced a more elongated cellular morphology and promoted cell migration and invasion. Migration was increased in the presence of the extracellular matrix (ECM) proteins osteopontin and fibronectin and the basement membrane proteins collagen IV and laminin I. TRAP-induced properties were reverted upon shRNA-mediated knockdown of TRAP or treatment with the small molecule TRAP inhibitor 5-PNA. Global phosphoproteomics and proteomics analyses identified possible substrates of TRAP phosphatase activity or signaling intermediates and outlined a TRAP-dependent regulation of proteins involved in cell adhesion and ECM organization. Upregulation of TGFβ isoform 2 (TGFβ2), TGFβ receptor type 1 (TβR1) and Mothers against decapentaplegic homolog 2 (SMAD2), as well as increased intracellular phosphorylation of CD44 were identified upon TRAP perturbation. Functional antibody-mediated blocking and chemical inhibition demonstrated that TRAP-dependent migration and proliferation is regulated via TGFβ2/TβR, whereas proliferation beyond basal levels is regulated through CD44.

CONCLUSION

Altogether, TRAP promotes metastasis-related cell properties in MDA-MB-231 breast cancer cells via TGFβ2/TβR and CD44, thereby identifying a potential signaling mechanism associated to TRAP action in breast cancer cells.

Role of the extracellular matrix in cancer-associated epithelial to mesenchymal transition phenomenon

The epithelial to mesenchymal transition (EMT) program is a crucial component in the processes of morphogenesis and embryonic development. The transition of epithelial to mesenchymal phenotype is associated with numerous structural and functional changes, including loss of cell polarity and tight cell-cell junctions, the acquisition of invasive abilities, and the expression of mesenchymal proteins. The switch between the two phenotypes is involved in human pathology and is crucial for cancer progression. Extracellular matrices (ECMs) are multi-component networks that surround cells in tissues. These networks are obligatory for cell survival, growth, and differentiation as well as tissue organization. Indeed, the ECM suprastructure, in addition to its supportive role, can process and deliver a plethora of signals to cells, which ultimately regulate their behavior. Importantly, the ECM derived signals are critically involved in the process of EMT during tumorigenesis. This review discusses the multilayer interaction between the ECM and the EMT process, focusing on contributions of discrete mediators, a strategy that may identify novel potential target molecules. Developmental Dynamics 247:368-381, 2018. © 2017 Wiley Periodicals, Inc.

TGF-β1/PTEN/PI3K signaling plays a critical role in the anti-proliferation effect of tetrandrine in human colon cancer cells

The diagnosis and treatment for colon cancer have been greatly developed, but the prognosis remains unsatisfactory. There is still a great clinical need to explore new efficacious drugs for colon cancer treatment. Tetrandrine (Tet) is a bis-benzylisoquinoline alkaloid. It has been shown that Tet may be a potential candidate for cancer treatment, but the explicit mechanism underlying this activity remains unclear. In this study, we investigated the anticancer activity of Tet in human colon cancer cells and dissected the possible mechanism. With cell viability assay and flow cytometry analysis, we confirmed that Tet can effectively inhibit the proliferation and induce apoptosis in HCT116 cells. Mechanically, we found that Tet greatly increases the mRNA and protein level of TGF-β1 in HCT116 cells. Exogenous TGF-β1 enhances the anti-proliferation and apoptosis inducing effect of Tet in HCT116 cells, which has been partly reversed by TGF-β1 inhibitor. Tet decreases the phosphorylation of Akt1/2/3 in HCT116 cells. This effect can be enhanced by exogenous TGF-β1, but partly reversed by TGF-β1 inhibitor. Tet exhibits no effect on total level of PTEN, but decreases the phosphorylation of PTEN; exogenous TGF-β1 enhances the effect of Tet on decreasing the phosphorylation of PTEN, which was partly reversed by TGF-β1 inhibitor. Our findings suggested that Tet may be a promising candidate for colon cancer treatment, and the anticancer activity may be mediated by inactivating PI3K/Akt signaling through upregulating TGF-β1 to decrease the phosphorylation of PTEN.

Aberrant Splicing of Estrogen Receptor, HER2, and CD44 Genes in Breast Cancer

Breast cancer (BC) is the most common cause of cancer-related death among women under the age of 50 years. Established biomarkers, such as hormone receptors (estrogen receptor [ER]/progesterone receptor) and human epidermal growth factor receptor 2 (HER2), play significant roles in the selection of patients for endocrine and trastuzumab therapies. However, the initial treatment response is often followed by tumor relapse with intrinsic resistance to the first-line therapy, so it has been expected to identify novel molecular markers to improve the survival and quality of life of patients. Alternative splicing of pre-messenger RNAs is a ubiquitous and flexible mechanism for the control of gene expression in mammalian cells. It provides cells with the opportunity to create protein isoforms with different, even opposing, functions from a single genomic locus. Aberrant alternative splicing is very common in cancer where emerging tumor cells take advantage of this flexibility to produce proteins that promote cell growth and survival. While a number of splicing alterations have been reported in human cancers, we focus on aberrant splicing of ER, HER2, and CD44 genes from the viewpoint of BC development. ERα36, a splice variant from the ER1 locus, governs nongenomic membrane signaling pathways triggered by estrogen and confers 4-hydroxytamoxifen resistance in BC therapy. The alternative spliced isoform of HER2 lacking exon 20 (Δ16HER2) has been reported in human BC; this isoform is associated with transforming ability than the wild-type HER2 and recapitulates the phenotypes of endocrine therapy-resistant BC. Although both CD44 splice isoforms (CD44s, CD44v) play essential roles in BC development, CD44v is more associated with those with favorable prognosis, such as luminal A subtype, while CD44s is linked to those with poor prognosis, such as HER2 or basal cell subtypes that are often metastatic. Hence, the detection of splice variants from these loci will provide keys to understand the pathogenesis, predict the prognosis, and choose specific therapies for BC.

Expression of ALDH1 and TGFβ2 in benign and malignant breast tumors and their prognostic implications

The specific mechanism underlying the role of putative stem cell marker aldehyde dehydrogenase 1 (ALDH1) playing in development and progression of breast cancer is currently unclear. Transforming growth factor β (TGFβ) signaling pathway is reported to be activated in most cancers. Thus a study was initiated to explore possible differences and correlation of ALDH1 and TGFβ2 expression in the most common malignant and benign tumors of the breast in Chinese women. Samples of 75 breast cancer tissues, 30 paracancerous normal tissues, and 39 fibroadenoma breast tissues were investigated for the expression of ALDH1 and TGFβ2 using immunohistochemistry. The positive rates of ALDH1 and TGFβ2 protein were 62.67% and 66.67%, respectively, in breast cancer tissues, which were significantly higher than that in normal fibroadenoma breast (P<0.05) and paracancerous tissues (P<0.01). ALDH1 and TGFβ2 status were significantly associated with tumor histological grade and receptor status (P<0.05). Expression of ALDH1 was found to be positively correlative to TGFβ2 in breast cancer (r = 0.33, P<0.01). Expression of both proteins remained significantly associated with reduced overall survival (OS) by univariate analysis (P<0.05). Multivariate Cox regression analysis showed that ALDH1 expression, tumor stage, and lymph node status are independent prognostic factors in invasive breast cancer patients. Thus ALDH1 and TGFβ2 play important roles in the development of breast cancer. The ALDH1 phenotype is an independent predictor of poor prognosis, and TGFβ2 signaling pathway activation might be involved in the pathological regulation of ALDH1 in breast cancer.

HAS2 and CD44 in breast tumorigenesis

Metastatic spread of breast cancer cells, facilitated by the epithelial-mesenchymal transition (EMT) process, is responsible for the majority of breast cancer mortality. Increased levels of hyaluronan due to deregulation of hyaluronan-synthesizing enzymes, like HAS2, and expression of CD44, the key receptor for hyaluronan, are correlated to poor outcome of patients with basal-like breast cancer. TGFβ induces HAS2 and CD44, both of which are required in the course of efficient TGFβ-induced EMT processes by mammary epithelial cells. Elucidation of the molecular mechanisms underlying tumor-stroma interactions in breast cancer including the regulation of HAS2 and CD44 expression may contribute to the development of better strategies to treat breast cancer patients.