Recombinant human PRG4 (rhPRG4) suppresses breast cancer cell invasion by inhibiting TGFβ-Hyaluronan-CD44 signalling pathway

PRG4 mitigates hemorrhagic shock-induced cardiac injury by inhibiting mitochondrial dysregulation, oxidative stress and NLRP3-mediated pyroptosis

Hemorrhagic shock (HS) is one of the main causes of morbidity and death in patients with trauma or major surgery. Cardiac dysfunction is a well-known complication of HS. PRG4, also known as lubricin, is a mucin-like glycoprotein that plays anti-inflammatory and anti-apoptotic roles in a variety of diseases. In this study, we aimed to explore the cardioprotective efficacy of PRG4 in HS-induced cardiac injury. Employing the HS model and RNA-seq, we found that PRG4 was increased in the myocardial tissue of rats after HS. In vivo studies suggested that HS led to abnormal hemodynamic parameters and increased cTnI levels, and PRG4 overexpression effectively reversed these changes. PRG4 also suppressed HS-induced mitochondrial disorders, as reflected by increased mitochondrial membrane potential (MMP), ATP and mitochondria cytochrome c, COXIV and TOM20, as well as decreased BNIP3L and cytoplasmic cytochrome c. Furthermore, HS led to enhanced oxidative stress, as evidenced by upregulated ROS and MDA contents, and downregulated SOD and CAT activities, and these alterations were negated by PRG4 overexpression. Notably, PRG4 repressed the NLRP3-mediated pyroptosis pathway, as illustrated by decreased NLRP3 levels, caspase-1 activity and GSDMD-NT levels. In summary, these observations indicate that PRG4 overexpression protects against HS-induced cardiac dysfunction by inhibiting mitochondrial dysregulation, oxidative stress and NLRP3-mediated pyroptosis.

PRG4 represses the genesis and metastasis of osteosarcoma by inhibiting PDL1 expression

BACKGROUND

Osteosarcoma is originated from skeletal system. Recombinant human proteoglycan 4 (rhPRG4) can inhibit cell proliferation and migration in multiple cancers. This research is designed to dig out the role and mechanism of PRG4 in osteosarcoma.

METHODS

Human osteosarcoma cell lines, MG63 and 143B, were transfected with programmed death 1 (PD-L1) overexpression vectors and/or treated with 20, 50, and 100 μg/mL rhPRG4, followed by the determination of cell viability, colony formation, sphere formation, invasion, migration, apoptosis, and the expressions of matrix metalloproteinases (MMPs), PD-L1 and apoptosis-related proteins. Tumor-bearing mouse models were constructed by injection of 143B cells and treatment of anti-PD-L1 antibody and/or adenovirus PRG4 (AdPRG4). Tumor volume was monitored, and immunohistochemical location of Ki67 was performed. Expressions of MMPs, transforming growth factor-β (TGF-β), PD-L1, and epithelial mesenchymal transition (EMT)-related proteins were measured in tumors.

RESULTS

RhPRG4 (20, 50, and 100 μg/mL) inhibited the viability, colony formation, sphere formation, invasion, migration, and the expressions of MMP2, MMP9 and Bcl2 in osteosarcoma cells, while promoting cell apoptosis as well as Bax and c-caspase3 expressions, at a dose-dependent manner; by contrast, PD-L1 overexpression reversed the above effects of 100 μg/mL rhPRG4. AdPRG4 or anti-PD-L1 antibody decreased tumor volume, number of pulmonary metastasis nodule, Ki67 location, and expressions of TGF-β, PD-L1, MMP2, MMP9, Vimentin, and Snail, but increased E-cadherin expression in tumor cells. Moreover, anti-PD-L1 antibody and AdPRG4 together functioned more effectively than them alone in reducing tumor burden.

CONCLUSION

PRG4 represses the genesis and metastasis of osteosarcoma via inhibiting PD-L1 expression, and AdPRG4 enhances the effectiveness of anti-PD-L1 therapy.

PRG4 deficiency in mice alters skeletal structure, mechanics, and calvarial osteoclastogenesis, and rhPRG4 inhibits in vitro osteoclastogenesis

Osteoporosis is a chronic disease characterized by reduced bone mass and increased fracture risk, estimated to affect over 10 million people in the United States alone. Drugs used to treat bone loss often come with significant limitations and/or long-term safety concerns. Proteoglycan-4 (PRG4, also known as lubricin) is a mucin-like glycoprotein best known for its boundary lubricating function of articular cartilage. In more recent years, it has been shown that PRG4 has anti-inflammatory properties, contributes to the maintenance of subchondral bone integrity, and patients with PRG4 mutations are osteopenic. However, it remains unknown how PRG4 impacts mechanical and material properties of bone. Therefore, our objective was to perform a phenotyping study of bone in a Prg4 gene trap (GT) mouse (PRG4 deficient). We found that femurs of Prg4 GT mice have altered mechanical, structural, and material properties relative to wildtype littermates. Additionally, Prg4 GT mice have a greater number of calvarial osteoclasts than wildtype mice, but do not have a notable inflammatory serum profile. Finally, Prg4 GT mice do not have an altered rate of bone formation, and exogenous recombinant human PRG4 (rhPRG4) administration inhibited osteoclastogenesis in vitro, suggesting that the skeletal phenotype may be due to changes in bone resorption. Overall, this work demonstrates that PRG4 deficiency affects several integral properties of bone structure, mechanics, and skeletal cell activity, and provides the foundation and insight toward future work evaluating PRG4 as a potential therapeutic target in treating bone loss.

Informed by Cancer Stem Cells of Solid Tumors: Advances in Treatments Targeting Tumor-Promoting Factors and Pathways

Cancer stem cells (CSCs) represent a subpopulation within tumors that promote cancer progression, metastasis, and recurrence due to their self-renewal capacity and resistance to conventional therapies. CSC-specific markers and signaling pathways highly active in CSCs have emerged as a promising strategy for improving patient outcomes. This review provides a comprehensive overview of the therapeutic targets associated with CSCs of solid tumors across various cancer types, including key molecular markers aldehyde dehydrogenases, CD44, epithelial cellular adhesion molecule, and CD133 and signaling pathways such as Wnt/β-catenin, Notch, and Sonic Hedgehog. We discuss a wide array of therapeutic modalities ranging from targeted antibodies, small molecule inhibitors, and near-infrared photoimmunotherapy to advanced genetic approaches like RNA interference, CRISPR/Cas9 technology, aptamers, antisense oligonucleotides, chimeric antigen receptor (CAR) T cells, CAR natural killer cells, bispecific T cell engagers, immunotoxins, drug-antibody conjugates, therapeutic peptides, and dendritic cell vaccines. This review spans developments from preclinical investigations to ongoing clinical trials, highlighting the innovative targeting strategies that have been informed by CSC-associated pathways and molecules to overcome therapeutic resistance. We aim to provide insights into the potential of these therapies to revolutionize cancer treatment, underscoring the critical need for a multi-faceted approach in the battle against cancer. This comprehensive analysis demonstrates how advances made in the CSC field have informed significant developments in novel targeted therapeutic approaches, with the ultimate goal of achieving more effective and durable responses in cancer patients.

Interrogations of single-cell RNA splicing landscapes with SCASL define new cell identities with physiological relevance

RNA splicing shapes the gene regulatory programs that underlie various physiological and disease processes. Here, we present the SCASL (single-cell clustering based on alternative splicing landscapes) method for interrogating the heterogeneity of RNA splicing with single-cell RNA-seq data. SCASL resolves the issue of biased and sparse data coverage on single-cell RNA splicing and provides a new scheme for classifications of cell identities. With previously published datasets as examples, SCASL identifies new cell clusters indicating potentially precancerous and early-tumor stages in triple-negative breast cancer, illustrates cell lineages of embryonic liver development, and provides fine clusters of highly heterogeneous tumor-associated CD4 and CD8 T cells with functional and physiological relevance. Most of these findings are not readily available via conventional cell clustering based on single-cell gene expression data. Our study shows the potential of SCASL in revealing the intrinsic RNA splicing heterogeneity and generating biological insights into the dynamic and functional cell landscapes in complex tissues.

Identification of common factors among fibrosarcoma, rhabdomyosarcoma, and osteosarcoma by network analysis

Sarcoma cancers are uncommon malignant tumors, and there are many subgroups, including fibrosarcoma (FS), which mainly affects middle-aged and older adults in deep soft tissues. Rhabdomyosarcoma (RMS), on the other hand, is the most common soft-tissue sarcoma in children and is located in the head and neck area. Osteosarcomas (OS) is the predominant form of primary bone cancer among young adults, primarily resulting from sporadically random mutations. This frequently results in the dissemination of cancer cells to the lungs, commonly known as metastasis. Mesodermal cells are the origin of sarcoma cancers. In this study, a rather radical approach has been applied. Instead of comparing homogenous cancer types, we focus on three main subtypes of sarcoma: fibrosarcoma, rhabdomyosarcoma, and osteosarcoma, and compare their gene expression with normal cell groups to identify the differentially expressed genes (DEGs). Next, by applying protein-protein interaction (PPI) network analysis, we determine the hub genes and crucial factors, such as transcription factors (TFs), affected by these types of cancer. Our findings indicate a modification in a range of pathways associated with cell cycle, extracellular matrix, and DNA repair in these three malignancies. Results showed that fibrosarcoma (FS), rhabdomyosarcoma (RMS), and osteosarcoma (OS) had 653, 1270, and 2823 differentially expressed genes (DEGs), respectively. Interestingly, there were 24 DEGs common to all three types. Network analysis showed that the fibrosarcoma network had two sub-networks identified in FS that contributed to the catabolic process of collagen via the G-protein coupled receptor signaling pathway. The rhabdomyosarcoma network included nine sub-networks associated with cell division, extracellular matrix organization, mRNA splicing via spliceosome, and others. The osteosarcoma network has 13 sub-networks, including mRNA splicing, sister chromatid cohesion, DNA repair, etc. In conclusion, the common DEGs identified in this study have been shown to play significant and multiple roles in various other cancers based on the literature review, indicating their significance.

Redlining-associated methylation in breast tumors: the impact of contemporary structural racism on the tumor epigenome

Purpose

Place-based measures of structural racism have been associated with breast cancer mortality, which may be driven, in part, by epigenetic perturbations. We examined the association between contemporary redlining, a measure of structural racism at the neighborhood level, and DNA methylation in breast tumor tissue.

Methods

We identified 80 Black and White women diagnosed and treated for a first-primary breast cancer at Emory University Hospitals (2008-2017). Contemporary redlining was derived for census tracts using the Home Mortgage Disclosure Act database. Linear regression models were used to calculate the association between contemporary redlining and methylation in breast tumor tissue. We also examined epigenetic age acceleration for two different metrics, regressing β values for each cytosine-phosphate-guanine dinucleotide (CpG) site on redlining while adjusting for covariates. We employed multivariable Cox-proportional hazards models and 95% confidence intervals (CI) to estimate the association between aberrant methylation and mortality.

Results

Contemporary redlining was associated with 5 CpG sites after adjustment for multiple comparisons (FDR<0.10). All genes were implicated in breast carcinogenesis, including genes related to inflammation, immune function and stress response (ANGPT1, PRG4 and PRG4). Further exploration of the top 25 CpG sites, identified interaction of 2 sites (MRPS28 and cg11092048) by ER status and 1 site (GDP1) was associated with all-cause mortality. Contemporary redlining was associated with epigenetic age acceleration by the Hannum metric (β=5.35; CI 95%=0.30,10.4) and showed positive but non-significant correlation with the other clock.

Conclusion

We identified novel associations between neighborhood contemporary redlining and the breast tumor DNA methylome, suggesting that racist policies leading to inequitable social and environmental exposures, may impact the breast tumor epigenome. Additional research on the potential implications for prognosis is needed.

Sumoylated SnoN interacts with HDAC1 and p300/CBP to regulate EMT-associated phenotypes in mammary organoids

Protein post-translational modification by the small ubiquitin-like modifier (SUMO) regulates the stability, subcellular localization, and interactions of protein substrates with consequences on cellular responses including epithelial-mesenchymal transition (EMT). Transforming growth factor beta (TGFβ) is a potent inducer of EMT with implications for cancer invasion and metastasis. The transcriptional coregulator SnoN suppresses TGFβ-induced EMT-associated responses in a sumoylation-dependent manner, but the underlying mechanisms have remained largely unknown. Here, we find that sumoylation promotes the interaction of SnoN with the epigenetic regulators histone deacetylase 1 (HDAC1) and histone acetylase p300 in epithelial cells. In gain and loss of function studies, HDAC1 suppresses, whereas p300 promotes, TGFβ-induced morphogenetic changes associated with EMT-related events in three-dimensional multicellular organoids derived from mammary epithelial cells or carcinomas. These findings suggest that sumoylated SnoN acts via the regulation of histone acetylation to modulate EMT-related effects in breast cell organoids. Our study may facilitate the discovery of new biomarkers and therapeutics in breast cancer and other epithelial cell-derived cancers.

Quantifiable peptide library bridges the gap for proteomics based biomarker discovery and validation on breast cancer

Mass spectrometry (MS) based proteomics is widely used for biomarker discovery. However, often, most biomarker candidates from discovery are discarded during the validation processes. Such discrepancies between biomarker discovery and validation are caused by several factors, mainly due to the differences in analytical methodology and experimental conditions. Here, we generated a peptide library which allows discovery of biomarkers in the equal settings as the validation process, thereby making the transition from discovery to validation more robust and efficient. The peptide library initiated with a list of 3393 proteins detectable in the blood from public databases. For each protein, surrogate peptides favorable for detection in mass spectrometry was selected and synthesized. A total of 4683 synthesized peptides were spiked into neat serum and plasma samples to check their quantifiability in a 10 min liquid chromatography-MS/MS run time. This led to the PepQuant library, which is composed of 852 quantifiable peptides that cover 452 human blood proteins. Using the PepQuant library, we discovered 30 candidate biomarkers for breast cancer. Among the 30 candidates, nine biomarkers, FN1, VWF, PRG4, MMP9, CLU, PRDX6, PPBP, APOC1, and CHL1 were validated. By combining the quantification values of these markers, we generated a machine learning model predicting breast cancer, showing an average area under the curve of 0.9105 for the receiver operating characteristic curve.

TGF-B1-over-expressed adipose stem cells-derived secretome exhibits CD44 suppressor and anti-cancer properties via antagonistic effects against SMAD4 in breast cancer cells

OBJECTIVES

This study aimed to investigate the effect of TGF-B1-transfected adipose-derived mesenchymal stem cell (AD-MSC) conditional medium (TGF-B1-CM) on CD44 expression and biological activities in MCF-7 and MDA-MB-231 cells.

METHODS

In the study, the experimental groups were created as a standard medium, AD-MSC-CM, TGF-B1-CM, and TGF-B1 recombinant protein. The medium and proteins specified in these groups were applied to MCF-7 and MDA-MB-231 cells separately at 24, 48 and 72 hours. Western blot and immunofluorescent staining were performed with antibodies suitable for CD44 and canonical smad signaling pathway analyses between groups. Cellular proliferation in MCF-7 and MDA-MB-231 cells was measured by MTT. Biological activity analyses such as apoptosis, cell cycle, proliferation, DNA damage, and membrane depolarization between groups were tested on the Muse Cell Analyzer using appropriate kits. Cellular migration between groups was determined by showing cells that migrated to the scar area with in vitro scar formation. Statistics were performed with GraphPad Prism 8.02 software.

RESULTS

It was determined that TGF-B1-CM activates the smad signaling pathway in MCF-7 and MDA-MB-231 cells. TGF-B1-CM increased pSMAD2/3 expression and decreased SMAD4 expression in breast cancer cells. A decrease in CD44 expression was found at points of increase in pSMAD2/3 expression. Decreased expression of SMAD4 in breast cancer cells with TGF-B1-CM was associated with decreased expression of CD44. In MCF-7 and MDA-MB-231 cells, TGF-B1-CM was found to increase apoptosis, decrease proliferation, disrupt membrane depolarization, and arrest cells at G0/G1 stage. TGF-B1-CM suppressed MCF-7 and MDA-MB-231 migrations.

CONCLUSION

SMAD4-targeted therapeutic strategies may be considered to suppress CD44 expression in breast cancer cells. Both the anti-tumorigenic factors released by AD-MSCs and the secretomes obtained as a result of supporting these factors with the overexpression of TGF-B1, severely suppressed breast cancer cells. With this study, it was planned to obtain a targeted biological product that suppresses breast cancer cells in vitro.

Proteoglycan-4 predicts good prognosis in patients with hepatocellular carcinoma receiving transcatheter arterial chemoembolization and inhibits cancer cell migration in vitro

PURPOSE

To search for adaptive response molecules that affect the efficacy of transcatheter arterial chemoembolization (TACE), analyze their clinical correlation with and prognostic value for hepatocellular carcinoma (HCC), and explore their impact on cell biological behavior and their mechanisms of action.

METHODS

HCC tissue gene sequencing was used to identify differentially expressed genes. The expression of proteoglycan 4 (PRG4) in the serum of 117 patients with HCC who received TACE was detected by enzyme-linked immunosorbent assay. Serum-free medium mimicked TACE-induced nutrient deprivation. Cells with stable knockdown of PRG4 (shPRG4) were constructed to verify the effect and mechanism of PRG4 on the biological behavior of HCC cells in vitro.

RESULTS

The expression of PRG4 was significantly elevated under TACE-induced starvation conditions. Low PRG4 expression was associated with worse response to TACE treatment, shorter survival time, and stronger HCC migration ability. Furthermore, in vitro experiments showed that knockdown of PRG4 promoted HCC cell migration by enhancing epithelial-mesenchymal transition (EMT) while did not affect proliferation. When PRG4 expression was low, starvation treatment impaired the migratory ability of HCC cells and reduced the chemosensitivity of HCC cells to epirubicin.

CONCLUSIONS

PRG4 expression predicts survival and TACE treatment response in patients with HCC. Furthermore, knockdown of PRG4 enhanced EMT, leading to HCC cell migration. PRG4 may serve as a biomarker for HCC patients receiving TACE.

Noncovalent hyaluronan crosslinking by TSG-6: Modulation by heparin, heparan sulfate, and PRG4

The size, conformation, and organization of the glycosaminoglycan hyaluronan (HA) affect its interactions with soluble and cell surface-bound proteins. HA that is induced to form stable networks has unique biological properties relative to unmodified soluble HA. AlphaLISA assay technology offers a facile and general experimental approach to assay protein-mediated networking of HA in solution. Connections formed between two end-biotinylated 50 kDa HA (bHA) chains can be detected by signal arising from streptavidin-coated donor and acceptor beads being brought into close proximity when the bHA chains are bridged by proteins. We observed that incubation of bHA with the protein TSG-6 (tumor necrosis factor alpha stimulated gene/protein 6, TNFAIP/TSG-6) leads to dimerization or higher order multimerization of HA chains in solution. We compared two different heparin (HP) samples and two heparan sulfate (HS) samples for the ability to disrupt HA crosslinking by TSG-6. Both HP samples had approximately three sulfates per disaccharide, and both were effective in inhibiting HA crosslinking by TSG-6. HS with a relatively high degree of sulfation (1.75 per disaccharide) also inhibited TSG-6 mediated HA networking, while HS with a lower degree of sulfation (0.75 per disaccharide) was less effective. We further identified Proteoglycan 4 (PRG4, lubricin) as a TSG-6 ligand, and found it to inhibit TSG-6-mediated HA crosslinking. The effects of HP, HS, and PRG4 on HA crosslinking by TSG-6 were shown to be due to HP/HS/PRG4 inhibition of HA binding to the Link domain of TSG-6. Using the AlphaLISA platform, we also tested other HA-binding proteins for ability to create HA networks. The G1 domain of versican (VG1) effectively networked bHA in solution but required a higher concentration than TSG-6. Cartilage link protein (HAPLN1) and the HA binding protein segment of aggrecan (HABP, G1-IGD-G2) showed only low and variable magnitude HA networking effects. This study unambiguously demonstrates HA crosslinking in solution by TSG-6 and VG1 proteins, and establishes PRG4, HP and highly sulfated HS as modulators of TSG-6 mediated HA crosslinking.

CD44 Glycosylation as a Therapeutic Target in Oncology

The interaction of non-kinase transmembrane glycoprotein CD44 with ligands including hyaluronic acid (HA) is closely related to the occurrence and development of tumors. Changes in CD44 glycosylation can regulate its binding to HA, Siglec-15, fibronectin, TM4SF5, PRG4, FGF2, collagen and podoplanin and activate or inhibit c-Src/STAT3/Twist1/Bmi1, PI3K/AKT/mTOR, ERK/NF-κB/NANOG and other signaling pathways, thereby having a profound impact on the tumor microenvironment and tumor cell fate. However, the glycosylation of CD44 is complex and largely unknown, and the current understanding of how CD44 glycosylation affects tumors is limited. These issues must be addressed before targeted CD44 glycosylation can be applied to treat human cancers.

Tumor molecular differences associated with outcome disparities of Black patients with head and neck cancer

BACKGROUND

Numerous studies of head and neck squamous cell carcinoma (HNSCC) have demonstrated disparate outcomes by race and ethnicity. Beyond known associations with socioeconomic variables, whether these are also associated with differences in tumor molecular composition has thus far been poorly explored.

METHODS

We downloaded clinical and multiplatform molecular data from The Cancer Genome Atlas and other published studies. These were compared between non-Hispanic Black (n = 43) and White (n = 354) patients with non-HPV-related tumors, using multivariable models. Publicly available validation cohorts were used.

RESULTS

Black patients had poorer progression-free survival than White patients. Tumors of Black patients had greater copy number aberrations, and increased SFRP1 methylation and miRNA-mediated PRG4 silencing associated with poor survival. PI3K/AkT/mTOR pathway proteins were differentially expressed.

CONCLUSIONS

There are molecular differences between tumors of Black and White patients that may partially account for differences in survival. These may inform targeted treatment decisions to achieve equitable outcomes.

Proteoglycans in Cancer: Friends or Enemies? A Special Focus on Hepatocellular Carcinoma

Simple Summary

Proteoglycans affect multiple molecular and cellular processes during the progression of solid tumors with a highly desmoplastic stroma, such as HCC. Due to their role in enhancing or limiting the traits of cancer cells underlying their aggressiveness, such as proliferation, angiogenesis, epithelial to mesenchymal transition (EMT), and stemness, these macromolecules could be exploited as molecular targets or therapeutic agents. Proteoglycans, such as biglycan, versican, syndecan-1, glypican-3, and agrin, promote HCC cell proliferation, EMT, and angiogenesis, while endostatin and proteoglycan 4 were shown to impair cancer neovascularization or to enhance the sensitivity of HCC cells to drugs, such as sorafenib and regorafenib. Based on this evidence, interventional strategies involving the use of humanized monoclonal antibodies, T cells engineered with chimeric antigen receptors, or recombinant proteins mimicking potentially curative proteoglycans, are being employed or may be adopted in the near future for the treatment of HCC.

Abstract

Proteoglycans are a class of highly glycosylated proteins expressed in virtually all tissues, which are localized within membranes, but more often in the pericellular space and extracellular matrix (ECM), and are involved in tissue homeostasis and remodeling of the stromal microenvironment during physiological and pathological processes, such as tissue regeneration, angiogenesis, and cancer. In general, proteoglycans can perform signaling activities and influence a range of physical, chemical, and biological tissue properties, including the diffusivity of small electrolytes and nutrients and the bioavailability of growth factors. While the dysregulated expression of some proteoglycans is observed in many cancers, whether they act as supporters or limiters of neoplastic progression is still a matter of controversy, as the tumor promoting or suppressive function of some proteoglycans is context dependent. The participation of multiple proteoglycans in organ regeneration (as demonstrated for the liver in hepatectomy mouse models) and in cancer suggests that these molecules actively influence cell growth and motility, thus contributing to key events that characterize neoplastic progression. In this review, we outline the main roles of proteoglycans in the physiology and pathology of cancers, with a special mention to hepatocellular carcinoma (HCC), highlighting the translational potential of proteoglycans as targets or therapeutic agents for the treatment of this disease.

Mechanisms of Cell Adhesion Molecules in Endocrine-Related Cancers: A Concise Outlook

Chemotherapy is a critical treatment for endocrine-related cancers; however, chemoresistance and disease recurrence remain a challenge. The interplay between cancer cells and the tumor microenvironment via cell adhesion molecules (CAMs) promotes drug resistance, known as cell adhesion-mediated drug resistance (CAM-DR). CAMs are cell surface molecules that facilitate cell-to-cell or cell-to-extracellular matrix binding. CAMs exert an adhesion effect and trigger intracellular signaling that regulates cancer cell stemness maintenance, survival, proliferation, metastasis, epithelial-mesenchymal transition, and drug resistance. To understand these mechanisms, this review focuses on the role of CD44, cadherins, selectins, and integrins in CAM-DR in endocrine-related cancers.

Proteoglycan 4 (PRG4) expression and function in dry eye associated inflammation

Dry eye disease (DED) affects hundreds of millions of people worldwide. It is characterized by the production of inflammatory cytokines and chemokines as well as damaging matrix metalloproteinases (MMPs) at the ocular surface. While proteoglycan 4 (PRG4), a mucin-like glycoprotein present at the ocular surface, is most well known as a boundary lubricant that contributes to ocular surface integrity, it has been shown to blunt inflammation in various cell types, suggesting a dual mechanism of action. Recently, full-length recombinant human PRG4 (rhPRG4) has been shown to improve signs and symptoms of DED in humans. However, there remains a significant need for basic science research on rhPRG4's biological properties and its potential therapeutic mechanisms of action in treating DED. Therefore, the objectives of this study were to characterize endogenous PRG4 expression by telomerase-immortalized human corneal epithelial (hTCEpi) cells, examine whether exogenous rhPRG4 modulates cytokine and chemokine secretion in response to dry eye associated inflammation (TNFα and IL-1β), explore interactions between rhPRG4 and MMP-9, and understand how experimental dry eye (EDE) in mice affects PRG4 expression. PRG4 secretion from hTCEpi cells was quantified by Western blot and expression visualized by immunocytochemistry. Cytokine/chemokine production was measured by ELISA and Luminex, while rhPRG4's effect on MMP-9 activity, binding, and expression was quantified using an MMP-9 inhibitor kit, surface plasmon resonance, and reverse transcription polymerase chain reaction (RT-PCR), respectively. Finally, EDE was induced in mice, and PRG4 was visualized by immunohistochemistry in the cornea and by Western blot in lacrimal gland lysate. In vitro results demonstrate that hTCEpi cells synthesize and secrete PRG4, and PRG4 secretion is inhibited by TNFα and IL-1β. In response to these pro-inflammatory stresses, exogenous rhPRG4 significantly reduced the stimulated production of IP-10, RANTES, ENA-78, GROα, MIP-3α, and MIG, and trended towards a reduction of MIP-1α and MIP-1β. The hTCEpi cells were also able to internalize fluorescently-labelled rhPRG4, consistent with a mechanism of action that includes downstream biological signaling pathways. rhPRG4 was not digested by MMP-9, and it did not modulate MMP-9 gene expression in hTCEpi cells, but it was able to bind to MMP-9 and inhibited in vitro activity of exogenous MMP-9 in the presence of human tears. Finally, in vivo results demonstrate that EDE significantly decreased immunolocalization of PRG4 on the corneal epithelium and trended towards a reduction of PRG4 in lacrimal gland lysate. Collectively these results demonstrate rhPRG4 has anti-inflammatory properties on corneal epithelial cells, particularly as it relates to mitigating chemokine production, and is an inhibitor of MMP-9 activity, as well as that in vivo expression of PRG4 can be altered in preclinical models of DED. In conclusion, these findings contribute to our understanding of PRG4's immunomodulatory properties in the context of DED inflammation and provide the foundation and motivation for further mechanistic research of PRG4's properties on the ocular surface as well as expanding clinical evaluation of its ability as a multifunctional therapeutic agent to effectively provide relief to those who suffer from DED.

The role of CD44 in cancer chemoresistance: A concise review

CD44 is a cell surface adhesion molecule, which is overexpressed on cancer stem cells. The interaction of CD44 with hyaluronan is responsible for tumor development, metastasis, and expression of the chemoresistant phenotype. The overexpression of CD44 impedes the cytotoxic effect of chemotherapy medications in various cancers. Therefore, the high expression of CD44 is associated with a poor prognosis in affected patients. This high expression of CD44 in various cancers has provided an ample opportunity for the treatment of patients with chemoresistant malignancy. This review aims to demonstrate the various cross-talk between CD44 and intracellular and extracellular factors and highlight its role in developing chemoresistant tumors in some troublesome cancers.

Proteoglycan 4 Reduces Neuroinflammation and Protects the Blood-Brain Barrier after Traumatic Brain Injury

Neuroinflammation and dysfunction of the blood-brain barrier (BBB) are two prominent mechanisms of secondary injury in neurotrauma. It has been suggested that Toll-like receptors (TLRs) play important roles in initiating and propagating neuroinflammation resulting from traumatic brain injury (TBI), but potential beneficial effects of targeting these receptors in TBI have not been broadly studied. Here, we investigated the effect of targeting TLRs with proteoglycan 4 (PRG4) on post-traumatic neuroinflammation and BBB function. PRG4 is a mucinous glycoprotein with strong anti-inflammatory properties, exerting its biological effects by interfering with TLR2/4 signaling. In addition, PRG4 has the ability to inhibit activation of cluster of differentiation 44 (CD44), a cell-surface glycoprotein playing an important role in inflammation. Using the controlled cortical impact model of TBI in rats, we showed a rapid and prolonged upregulation of message for TLR2/4 and CD44 in the injured cortex. In the in vitro model of the BBB, recombinant human PRG4 (rhPRG4) crossed the endothelial monolayers through a high-capacity, saturable transport system. In rats sustaining TBI, PRG4 delivery to the brain was enhanced by post-traumatic increase in BBB permeability. rhPRG4 injected intravenously at 1 h post-TBI potently inhibited post-traumatic activation of nuclear factor kappa B and extracellular signal-regulated kinases 1/2, the two major signal transduction pathways associated with TLR2/4 and CD44, and curtailed the post-traumatic influx of monocytes. In addition, PRG4 restored normal BBB function after TBI by preventing the post-traumatic loss of tight junction protein claudin 5 and reduced neuronal death. Our observations provide support for therapeutic strategies targeting TLRs in TBI.

Prognostic Effect of Inflammatory Genes on Stage I-III Colorectal Cancer-Integrative Analysis of TCGA Data

Simple Summary

Research interest in the role of inflammation in the progression and prognosis of colorectal cancer (CRC) is growing. In this study, we evaluated the expression and DNA methylation levels of inflammation-related genes in CRC tissues using the TCGA-COREAD dataset by integratively combining multi-omics features using machine learning. Statistical analysis was additionally performed to allow for interpretable, understandable, and clinically practical results. An integrative model combining expression, methylation, and clinical features had the highest performance. In multivariate analysis, the methylation levels of CEP250, RAB21, and TNPO3 were significantly associated with overall survival. Our study results implicate the importance of integrating expression and methylation information along with clinical information in the prediction of survival. CEP250, RAB21, and TNPO3 in the prediction model might have a crucial role in CRC prognosis and further improve our understanding of potential mechanisms linking inflammatory reactions and CRC progression.

Abstract

Background inflammatory status indicators have been reported as prognostic biomarkers of colorectal cancer (CRC). However, since inflammatory interactions with the colon involve various modes of action, the biological mechanism linking inflammation and CRC prognosis has not been fully elucidated. We comprehensively evaluated the predictive roles of the expression and methylation levels of inflammation-related genes for CRC prognosis and their pathophysiological associations. Method. An integrative analysis of 247 patients with stage I-III CRC from The Cancer Genome Atlas was conducted. Lasso-penalized Cox proportional hazards regression (Lasso-Cox) and statistical Cox proportional hazard regression (CPH) were used for the analysis. Results. Models to predict overall survival were designed with respective combinations of clinical variables, including age, sex, stage, gene expression, and methylation. An integrative model combining expression, methylation, and clinical features performed better (median C-index = 0.756) than the model with clinical features alone (median C-index = 0.726). Based on multivariate CPH with features from the best model, the methylation levels of CEP250, RAB21, and TNPO3 were significantly associated with overall survival. They did not share any biological process in functional networks. The 5-year survival rate was 29.8% in the low methylation group of CEP250 and 79.1% in the high methylation group (p < 0.001). Conclusion. Our study results implicate the importance of integrating expression and methylation information along with clinical information in the prediction of survival. CEP250, RAB21, and TNPO3 in the prediction model might have a crucial role in CRC prognosis and further improve our understanding of potential mechanisms linking inflammatory reactions and CRC progression.

The Breast Cancer Stem Cells Traits and Drug Resistance

Drug resistance is a major challenge in breast cancer (BC) treatment at present. Accumulating studies indicate that breast cancer stem cells (BCSCs) are responsible for the BC drugs resistance, causing relapse and metastasis in BC patients. Thus, BCSCs elimination could reverse drug resistance and improve drug efficacy to benefit BC patients. Consequently, mastering the knowledge on the proliferation, resistance mechanisms, and separation of BCSCs in BC therapy is extremely helpful for BCSCs-targeted therapeutic strategies. Herein, we summarize the principal BCSCs surface markers and signaling pathways, and list the BCSCs-related drug resistance mechanisms in chemotherapy (CT), endocrine therapy (ET), and targeted therapy (TT), and display therapeutic strategies for targeting BCSCs to reverse drug resistance in BC. Even more importantly, more attention should be paid to studies on BCSC-targeted strategies to overcome the drug resistant dilemma of clinical therapies in the future.

Proteoglycan-4 is correlated with longer survival in HCC patients and enhances sorafenib and regorafenib effectiveness via CD44 in vitro

Sorafenib and regorafenib administration is among the preferential approaches to treat hepatocellular carcinoma (HCC), but does not provide satisfactory benefits. Intensive crosstalk occurring between cancer cells and other multiple non-cancerous cell subsets present in the surrounding microenvironment is assumed to affect tumor progression. This interplay is mediated by a number of soluble and structural extracellular matrix (ECM) proteins enriching the stromal milieu. Here we assess the HCC tumor expression of the ECM protein proteoglycan 4 (PRG4) and its potential pharmacologic activity either alone, or in combination with sorafenib and regorafenib. PRG4 mRNA levels resulted strongly correlated with increased survival rate of HCC patients (p = 0.000) in a prospective study involving 78 HCC subjects. We next showed that transforming growth factor beta stimulates PRG4 expression and secretion by primary human HCC cancer-associated fibroblasts, non-invasive HCC cell lines, and ex vivo specimens. By functional tests we found that recombinant human PRG4 (rhPRG4) impairs HCC cell migration. More importantly, the treatment of HCC cells expressing CD44 (the main PRG4 receptor) with rhPRG4 dramatically enhances the growth-limiting capacity of sorafenib and regorafenib, whereas not significantly affecting cell proliferation per se. Conversely, rhPRG4 only poorly potentiates drug effectiveness on low CD44-expressing or stably CD44-silenced HCC cells. Overall, these data suggest that the physiologically-produced compound PRG4 may function as a novel tumor-suppressive agent by strengthening sorafenib and regorafenib effects in the treatment of HCC.

Recombinant Human Proteoglycan-4 Mediates Interleukin-6 Response in Both Human and Mouse Endothelial Cells Induced Into a Sepsis Phenotype

OBJECTIVES

Sepsis is a leading cause of death in the United States. Putative targets to prevent systemic inflammatory response syndrome include antagonism of toll-like receptors 2 and 4 and CD44 receptors in vascular endothelial cells. Proteoglycan-4 is a mucinous glycoprotein that interacts with CD44 and toll-like receptor 4 resulting in a blockade of the NOD-like receptor pyrin domain-containing-3 pathway. We hypothesized that endothelial cells induced into a sepsis phenotype would have less interleukin-6 expression after recombinant human proteoglycan 4 treatment in vitro.

DESIGN

Enzyme-linked immunosorbent assay and reverse transcriptase-quantitative polymerase chain reaction to measure interleukin-6 protein and gene expression.

SETTING

Research laboratory.

SUBJECTS

Human umbilical vascular endothelial cells, human lung microvascular endothelial cells, and transgenic mouse (wild type) (Cd44 +/+/Prg4 +/+), Cd44 -/- (Cd44 tm1Hbg Prg4 +/+), Prg4 GT/GT (Cd44 +/+ Prg4 tm2Mawa/J), and double knockout (Cd44 tm1Hbg Prg4 tm2Mawa/J) lung microvascular endothelial cells.

INTERVENTIONS

Cells were treated with 100 or 250 ng/mL lipopolysaccharide-Escherichia coli K12 and subsequently treated with recombinant human proteoglycan 4 after 30 minutes. Interleukin-6 levels in conditioned media were measured via enzyme-linked immunosorbent assay and gene expression was measured via reverse transcriptase-quantitative polymerase chain reaction with ΔΔ-Ct analysis. Additionally, human umbilical vascular endothelial cells and human lung microvascular endothelial cells were treated with 1:10 diluted plasma from 15 patients with sepsis in culture media. After 30 minutes, either 50 or 100 µg/mL recombinant human proteoglycan 4 was administered. Interleukin-6 protein and gene expression were assayed. Proteoglycan 4 levels were also compared between control and sepsis patient plasma.

MEASUREMENTS AND MAIN RESULTS

Human umbilical vascular endothelial cell, human lung microvascular endothelial cell, and mouse lung microvascular endothelial cell treated with lipopolysaccharide had significantly increased interleukin-6 protein compared with controls. Recombinant human proteoglycan-4 significantly reduced interleukin-6 in human and mouse endothelial cells. Interleukin-6 gene expression was significantly increased after lipopolysaccharide treatment compared with controls. This response was reversed by 50 or 100 µg/mL recombinant human proteoglycan-4 in 80% of sepsis samples in human umbilical vascular endothelial cells and in 60-73% in human lung microvascular endothelial cells. In Cd44 -/- genotypes of the mouse lung microvascular endothelial cells, recombinant human proteoglycan-4 significantly reduced interleukin-6 protein levels after lipopolysaccharide treatment, indicating that Cd44 is not needed for recombinant human proteoglycan-4 to have an effect in a toll-like receptor 4 agonist inflammation model. Patient sepsis samples had higher plasma levels of native proteoglycan-4 than controls.

INTERPRETATION AND CONCLUSIONS

Recombinant human proteoglycan-4 is a potential adjunct therapy for sepsis patients and warrants future in vivo model studies.

Single-Cell Transcriptomic Analysis of Tumor-Derived Fibroblasts and Normal Tissue-Resident Fibroblasts Reveals Fibroblast Heterogeneity in Breast Cancer

Cancer-associated fibroblasts (CAFs) are a prominent stromal cell type in solid tumors and molecules secreted by CAFs play an important role in tumor progression and metastasis. CAFs coexist as heterogeneous populations with potentially different biological functions. Although CAFs are a major component of the breast cancer stroma, molecular and phenotypic heterogeneity of CAFs in breast cancer is poorly understood. In this study, we investigated CAF heterogeneity in triple-negative breast cancer (TNBC) using a syngeneic mouse model, BALB/c-derived 4T1 mammary tumors. Using single-cell RNA sequencing (scRNA-seq), we identified six CAF subpopulations in 4T1 tumors including: 1) myofibroblastic CAFs, enriched for α-smooth muscle actin and several other contractile proteins; 2) ‘inflammatory’ CAFs with elevated expression of inflammatory cytokines; and 3) a CAF subpopulation expressing major histocompatibility complex (MHC) class II proteins that are generally expressed in antigen-presenting cells. Comparison of 4T1-derived CAFs to CAFs from pancreatic cancer revealed that these three CAF subpopulations exist in both tumor types. Interestingly, cells with inflammatory and MHC class II-expressing CAF profiles were also detected in normal breast/pancreas tissue, suggesting that these phenotypes are not tumor microenvironment-induced. This work enhances our understanding of CAF heterogeneity, and specifically targeting these CAF subpopulations could be an effective therapeutic approach for treating highly aggressive TNBCs.

Lubricin as a Therapeutic and Potential Biomarker in Sepsis

Proteoglycan 4 (or lubricin), a mucin-like glycoprotein, was originally classified as a lubricating substance within diarthrodial joints. More recently, lubricin has been found in other tissues and has been implicated in 2 inflammatory pathways within the cell, via the Toll-like receptors (TLRs) and CD44. Lubricin is an antagonist of TLR2 and TLR4, and appears to enter cells via the CD44 receptor. Because of lubricin's action on these receptors, downstream processes of inflammation are halted, thereby preventing release of cytokines (a hallmark of inflammation and sepsis) from the cell, indicating lubricin's role as a biomarker and possible therapeutic for sepsis.

Oxidized low density lipoprotein receptor 1 promotes lung metastases of osteosarcomas through regulating the epithelial-mesenchymal transition

BACKGROUND

Oxidized low density lipoprotein receptor 1 (OLR1), a type II membrane protein, has been identified as receptor for oxidized low-density lipoprotein. The current study firstly provided evidence that OLR1 regulated EMT and thus promoted lung metastases in osteosarcoma (OS).

METHOD

All relevant experiments were conducted according to the manufacturer's protocols. In vivo tumor xenograft experiments were carried out in 6- to 16-week-old mice, then maintained in our animal facility under pathogen-free conditions in accordance with the Institutional Guidelines and approval by local authorities. For the use of the clinical materials for research purposes, prior patient's consent and approval from the Institute Research Ethics Committee were obtained. All statistical analyses were performed using IBM SPSS Statistics 22.0 for Windows.

RESULT

Microarrays were adopted to explore the underlying epigenetic mechanisms related to metastasis. 11 genes were identified among total 26,890 differentially expressed genes. After validated in paired primary and metastatic tissues, OLR1 was selected in the current study. The expression levels of OLR1 were tested in 4 widely used cell lines. Cell proliferation, migration and invasion could be enhanced when OLR1 was overexpressed. OLR1 overexpression also triggered G1 to S + G2 phases of cell cycle. Accordingly, cell proliferations, migration and invasion would be reduced when OLR1 was silenced. OLR1-silencing blocked G1 to S + G2 phases of cell cycle. Also, OLR1 silencing effectively suppressed local tumor carcinogenesis and lung metastases in vivo. Moreover, silencing OLR1 repressed the expression of mesenchymal markers (Snail, Twist, and N-cadherin), but induced an epithelial marker (E-cadherin).

CONCLUSION

This study indicated a novel molecular mechanism involving the role of OLR1 in lung metastases of osteosarcoma, strengthened the correlation between OLR1 and lung metastases.