Myeloid-derived macrophages and secreted HSP90α induce pancreatic ductal adenocarcinoma development

Extracellular heat shock protein 90 alpha (eHsp90α)'s role in cancer progression and the development of therapeutic strategies

Heat shock protein 90 alpha (Hsp90α) is an abundantly expressed and evolutionarily conserved molecular chaperone. Hsp90α is the inducible Hsp90 isoform, and its expression and secretion extracellularly (eHsp90α) can be triggered in response to a variety of cellular stresses to protect/activate client proteins and to facilitate cellular adjustment to the stress. As a result, cancers often have high expression levels of intracellular and extracellular (plasma) Hsp90α, allowing them to support their oncogenesis and progression. In fact, (e)Hsp90α has been implicated in regulating processes such as cell signaling transduction, DNA repair, promotion of the Epithelial-to-Mesenchymal Transition (EMT), promotion of angiogenesis, immune response, and cell migration. Hsp90α levels have been correlated with cancer progression and severity in several cancers, indicating that it may be a useful biomarker or drug-target for cancer. To date, the development of intracellular Hsp90α-targeted therapies include standard N-terminal ATP-competitive inhibitors and allosteric regulators that bind to Hsp90α's middle or C-terminal domain. On-target toxicities and dosing complications as a result of Hsp90α inhibition has driven the development of eHsp90α-targeted therapies. Examples include anti-Hsp90α monoclonal antibodies and cell-impermeable Hsp90α small molecule inhibitors. This review aims to discuss the many roles Hsp90α plays in cancer progression with a focus on the current development of Hsp90α-targeted therapies.

HSP90 multi-functionality in cancer

The 90-kDa heat shock proteins (HSP90s) are molecular chaperones essential for folding, unfolding, degradation and activity of a wide range of client proteins. HSP90s and their cognate co-chaperones are subject to various post-translational modifications, functional consequences of which are not fully understood in cancer. Intracellular and extracellular HSP90 family members (HSP90α, HSP90β, GRP94 and TRAP1) promote cancer by sustaining various hallmarks of cancer, including cell death resistance, replicative immortality, tumor immunity, angiogenesis, invasion and metastasis. Given the importance of HSP90 in tumor progression, various inhibitors and HSP90-based vaccines were developed for the treatment of cancer. Further understanding of HSP90 functions in cancer may provide new opportunities and novel therapeutic strategies for the treatment of cancer.

Development of a Humanized Antibody Targeting Extracellular HSP90α to Suppress Endothelial-Mesenchymal Transition-Enhanced Tumor Growth of Pancreatic Adenocarcinoma Cells

Extracellular HSP90α (eHSP90α) is a promoter of tumor development and malignant progression. Patients with malignancies, including pancreatic ductal adenocarcinoma (PDAC), have generally shown 5~10-fold increases in serum/plasma eHSP90α levels. In this study, we developed a humanized antibody HH01 to target eHSP90α and evaluated its anticancer efficacy. HH01, with novel complementarity-determining regions, exhibits high binding affinity toward HSP90α. It recognizes HSP90α epitope sites 235AEEKEDKEEE244 and 251ESEDKPEIED260, with critical amino acid residues E237, E239, D240, K241, E253, and K255. HH01 effectively suppressed eHSP90α-induced invasive and spheroid-forming activities of colorectal cancer and PDAC cell lines by blocking eHSP90α's ligation with the cell-surface receptor CD91. In mouse models, HH01 potently inhibited the tumor growth of PDAC cell grafts/xenografts promoted by endothelial-mesenchymal transition-derived cancer-associated fibroblasts while also reducing serum eHSP90α levels, reflecting its anticancer efficacy. HH01 also modulated tumor immunity by reducing M2 macrophages and reinvigorating immune T-cells. Additionally, HH01 showed low aggregation propensity, high water solubility, and a half-life time of >18 days in mouse blood. It was not cytotoxic to retinal pigmented epithelial cells and showed no obvious toxicity in mouse organs. Our data suggest that targeting eHSP90α with HH01 antibody can be a promising novel strategy for PDAC therapy.

Hsp90α and cell death in cancers: a review

Heat shock protein 90α (Hsp90α), an important molecular chaperone, plays a crucial role in regulating the activity of various intracellular signaling pathways and maintaining the stability of various signaling transduction proteins. In cancer, the expression level of Hsp90α is often significantly upregulated and is recognized as one of the key factors in cancer cell survival and proliferation. Cell death can help achieve numerous purposes, such as preventing aging, removing damaged or infected cells, facilitating embryonic development and tissue repair, and modulating immune response. The expression of Hsp90α is closely associated with specific modes of cell death including apoptosis, necrotic apoptosis, and autophagy-dependent cell death, etc. This review discusses the new results on the relationship between expression of Hsp90α and cell death in cancer. Hsp90α is frequently overexpressed in cancer and promotes cancer cell growth, survival, and resistance to treatment by regulating cell death, rendering it a promising target for cancer therapy.

The Distinct Assignments for Hsp90α and Hsp90β: More Than Skin Deep

For decades, the undisputable definition of the cytosolic Hsp90α and hsp90β proteins being evolutionarily conserved, ATP-driven chaperones has ruled basic research and clinical trials. The results of recent studies, however, have fundamentally challenged this paradigm, not to mention the spectacular failures of the paradigm-based clinical trials in cancer and beyond. We now know that Hsp90α and Hsp90β are both ubiquitously expressed in all cell types but assigned for distinct and irreplaceable functions. Hsp90β is essential during mouse development and Hsp90α only maintains male reproductivity in adult mice. Neither Hsp90β nor Hsp90α could substitute each other under these biological processes. Hsp90β alone maintains cell survival in culture and Hsp90α cannot substitute it. Hsp90α also has extracellular functions under stress and Hsp90β does not. The dramatic difference in the steady-state expression of Hsp90 in different mouse organs is due to the variable expressions of Hsp90α. The lowest expression of Hsp90 is less than 2% and the highest expression of Hsp90 is 9% among non-transformed cell lines. The two linker regions only take up less than 5% of the Hsp90 proteins, but harbor 21% of the total amino acid substitutions, i.e., 40% in comparison to the 86% overall amino acid homology. A full understanding of the distinctions between Hsp90α and Hsp90β could lead to new, safe and effective therapeutics targeting Hsp90 in human disorders such as cancer. This is the first comprehensive review of a comparison between the two cytosolic Hsp90 isoforms.

Analysis of the prognostic, diagnostic and immunological role of HSP90α in malignant tumors

Heat shock protein 90α (HSP90α) encoded by the HSP90AA1 gene, is the stress inducible isoform of the molecular chaperone HSP90, and was demonstrated as a promising hallmark to diagnose, prognosis in malignant tumors. This study is to evaluate the value of HSP90α in diagnosis, prognosis and immunotherapy of malignant tumors by investigating the expression of HSP90α in plasma of various tumors and analyzing the expression of HSP90α at gene and protein levels via pan-cancer database. We founded that levels of HSP90α in malignant tumors groups were significantly higher than healthy controls in serum. Pan-cancer analysis showed that HSP90AA1 was highly expressed in 27 of 33 tumors, but low in individual cancers (such as renal malignancies). The plasma HSP90α level was positively correlated with the stage of malignant tumor, but there was no significant difference between HSP90AA1 and the stage of most tumors. Cox regression analysis showed that HSP90AA1 expression was significantly correlated with OS in only 6 of the 32 cancers, including LIHC, KIRC, HNSC, LUAD, BRCA and MESO. Up-regulation of HSP90AA1 in most tumors was positively correlated with PDCD1LG2 and CD274 immune checkpoint genes. T cell CD8+ was positively correlated with HSP90AA1 in COAD, DLBC and UVM, and negatively correlated with HSP90AA1 in ESCA, GBM, HNSC, KIRC, KIRP, UCEC and STAD. The AUC of HSP90α are generally high in different tumor groups, which indicated its diagnostic value in malignant tumors. In conclusion, serum HSP90α in patients with malignant tumor is generally elevated, which is of positive significance as an independent diagnosis and combined diagnosis. However, we found that the expression level of HSP90AA1 gene in most tumors was not completely consistent with the serum level, and even down-regulated in some tumors. Plasma levels can be used as biomarkers of poor prognosis in some tumors, but it cannot be used as a biomarker for poor prognosis of all tumors, and more in-depth studies are needed.

Extracellular Heat Shock Protein-90 (eHsp90): Everything You Need to Know

“Extracellular” Heat Shock Protein-90 (Hsp90) was initially reported in the 1970s but was not formally recognized until 2008 at the 4th International Conference on The Hsp90 Chaperone Machine (Monastery Seeon, Germany). Studies presented under the topic of “extracellular Hsp90 (eHsp90)” at the conference provided direct evidence for eHsp90’s involvement in cancer invasion and skin wound healing. Over the past 15 years, studies have focused on the secretion, action, biological function, therapeutic targeting, preclinical evaluations, and clinical utility of eHsp90 using wound healing, tissue fibrosis, and tumour models both in vitro and in vivo. eHsp90 has emerged as a critical stress-responding molecule targeting each of the pathophysiological conditions. Despite the studies, our current understanding of several fundamental questions remains little beyond speculation. Does eHsp90 indeed originate from purposeful live cell secretion or rather from accidental dead cell leakage? Why did evolution create an intracellular chaperone that also functions as a secreted factor with reported extracellular duties that might be (easily) fulfilled by conventional secreted molecules? Is eHsp90 a safer and more optimal drug target than intracellular Hsp90 chaperone? In this review, we summarize how much we have learned about eHsp90, provide our conceptual views of the findings, and make recommendations on the future studies of eHsp90 for clinical relevance.

Extracellular HSPs: The Potential Target for Human Disease Therapy

Heat shock proteins (HSPs) are highly conserved stress proteins known as molecular chaperones, which are considered to be cytoplasmic proteins with functions restricted to the intracellular compartment, such as the cytoplasm or cellular organelles. However, an increasing number of observations have shown that HSPs can also be released into the extracellular matrix and can play important roles in the modulation of inflammation and immune responses. Recent studies have demonstrated that extracellular HSPs (eHSPs) were involved in many human diseases, such as cancers, neurodegenerative diseases, and kidney diseases, which are all diseases that are closely linked to inflammation and immunity. In this review, we describe the types of eHSPs, discuss the mechanisms of eHSPs secretion, and then highlight their functions in the modulation of inflammation and immune responses. Finally, we take cancer as an example and discuss the possibility of targeting eHSPs for human disease therapy. A broader understanding of the function of eHSPs in development and progression of human disease is essential for developing new strategies to treat many human diseases that are critically related to inflammation and immunity.

Targeting Proliferating Tumor-Infiltrating Macrophages Facilitates Spatial Redistribution of CD8+ T Cells in Pancreatic Cancer

Tumor-associated macrophages (TAMs) play crucial roles in cancer progression, but the contributions and regulation of different macrophage subpopulations remain unclear. Here, we report a high level of TAM infiltration in human and mouse pancreatic ductal adenocarcinoma (PDAC) models and that the targeting of proliferating F4/80+ macrophages facilitated cytotoxic CD8+ T-cell-dependent antitumor immune responses. A well-defined KPC-derived PDAC cell line and the murine Panc02 PDAC cell line were used. Treatment of PDAC-bearing mice with clodronate liposomes, an agent that chemically depletes macrophages, did not impact macrophage subpopulations in the local tumor microenvironment (TME). However, further investigation using both BrdU and Ki67 to evaluate proliferating cells showed that clodronate liposomes treatment reduced proliferating macrophages in the KPC and Panc02 models. We further evaluated the distance between CD8+ T cells and PanCK+ tumor cells, and clodronate liposomes treatment significantly increased the number of CD8+ T cells in close proximity (<30 µm) to PanCK+ PDAC cells, with increased numbers of tumor-infiltrating IFN-γ+CD8+ T cells. This study suggests that targeting proliferating tumor-infiltrating macrophages may increase CD8+ cytotoxic lymphocyte (CTL) infiltration and facilitate the spatial redistribution of CD8+ T cells in tumors, contributing to the antitumor effect.

Extracellular HSP90α Induces MyD88-IRAK Complex-Associated IKKα/β-NF-κB/IRF3 and JAK2/TYK2-STAT-3 Signaling in Macrophages for Tumor-Promoting M2-Polarization

M2-polarization and the tumoricidal to tumor-promoting transition are commonly observed with tumor-infiltrating macrophages after interplay with cancer cells or/and other stroma cells. Our previous study indicated that macrophage M2-polarization can be induced by extracellular HSP90α (eHSP90α) secreted from endothelial-to-mesenchymal transition-derived cancer-associated fibroblasts. To extend the finding, we herein validated that eHSP90α-induced M2-polarized macrophages exhibited a tumor-promoting activity and the promoted tumor tissues had significant increases in microvascular density but decreases in CD4⁺ T-cell level. We further investigated the signaling pathways occurring in eHSP90α-stimulated macrophages. When macrophages were exposed to eHSP90α, CD91 and toll-like receptor 4 (TLR4) functioned as the receptor/co-receptor for eHSP90α binding to recruit interleukin (IL)-1 receptor-associated kinases (IRAKs) and myeloid differentiation factor 88 (MyD88), and next elicited a canonical CD91/MyD88-IRAK1/4-IκB kinase α/β (IKKα/β)-nuclear factor-κB (NF-κB)/interferon regulatory factor 3 (IRF3) signaling pathway. Despite TLR4-MyD88 complex-associated activations of IKKα/β, NF-κB and IRF3 being well-known as involved in macrophage M1-activation, our results demonstrated that the CD91-TLR4-MyD88 complex-associated IRAK1/4-IKKα/β-NF-κB/IRF3 pathway was not only directly involved in M2-associated CD163, CD204, and IL-10 gene expressions but also required for downregulation of M1 inflammatory cytokines. Additionally, Janus kinase 2 (JAK2) and tyrosine kinase 2 (TYK2) were recruited onto MyD88 to induce the phosphorylation and activation of the transcription factor signal transducer and activator of transcription-3 (STAT-3). The JAK2/TYK2-STAT-3 signaling is known to associate with tumor promotion. In this study, the MyD88-JAK2/TYK2-STAT-3 pathway was demonstrated to contribute to eHSP90α-induced macrophage M2-polarization by regulating the expressions of M1- and M2-related genes, proangiogenic protein vascular endothelial growth factor, and phagocytosis-interfering factor Sec22b.

The HSP Immune Network in Cancer

Heat shock proteins are molecular chaperones which support tumor development by regulating various cellular processes including unfolded protein response, mitochondrial bioenergetics, apoptosis, autophagy, necroptosis, lipid metabolism, angiogenesis, cancer cell stemness, epithelial-mesenchymal transition and tumor immunity. Apart from their intracellular activities, HSPs have also distinct extracellular functions. However, the role that HSP chaperones play in the regulation of immune responses inside and outside the cell is not yet clear. Herein, we explore the intracellular and extracellular immunologic functions of HSPs in cancer. A broader understanding of how HSPs modulate immune responses may provide critical insights for the development of effective immunotherapies.

The dark-side of the outside: how extracellular heat shock proteins promote cancer

In addition to exerting several essential house-keeping activities in the cell, heat shock proteins (HSPs) are crucial players in a well-structured molecular program activated in response to stressful challenges. Among the different activities carried out by HSPs during emergency, they reach the extracellular milieu, from where they scout the surroundings, regulate extracellular protein activity and send autocrine and paracrine signals. Cancer cells permanently experience stress conditions due to their altered equilibrium and behaviour, and constantly secrete heat shock proteins as a result. Other than supporting anti-tumour immunity, extracellular heat shock proteins (eHSPs), can also exacerbate cancer cell growth and malignancy by sustaining different cancer hallmarks. eHSPs are implicated in extracellular matrix remodelling, resistance to apoptosis, promotion of cell migration and invasion, induction of epithelial to mesenchymal transition, angiogenesis and activation of stromal cells, supporting ultimately, metastasis dissemination. A broader understanding of eHSP activity and contribution to tumour development and progression is leading to new opportunities in the diagnosis and treatment of cancer.

Tumor-Associated Macrophages in Pancreatic Ductal Adenocarcinoma: Origin, Polarization, Function, and Reprogramming

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy. PDAC is only cured by surgical resection in its early stage, but there remains a relatively high possibility of recurrence. The development of PDAC is closely associated with the tumor microenvironment. Tumor-associated macrophages (TAMs) are one of the most abundant immune cell populations in the pancreatic tumor stroma. TAMs are inclined to M2 deviation in the tumor microenvironment, which promotes and supports tumor behaviors, including tumorigenesis, immune escape, metastasis, and chemotherapeutic resistance. Herein, we comprehensively reviewed the latest researches on the origin, polarization, functions, and reprogramming of TAMs in PDAC.

Comprehensive Analysis of LincRNAs in Classical and Basal-Like Subtypes of Pancreatic Cancer

Pancreatic ductal adenocarcinomas (PDAC) belong to the deadliest malignancies in the western world. Mutations in TP53 and KRAS genes along with some other frequent polymorphisms occur almost universally and are major drivers of tumour initiation. However, these mutations cannot explain the heterogeneity in therapeutic responses and differences in overall survival observed in PDAC patients. Thus, recent classifications of PDAC tumour samples have leveraged transcriptome-wide gene expression data to account for epigenetic, transcriptional and post-transcriptional mechanisms that may contribute to this deadly disease. Intriguingly, long intervening RNAs (lincRNAs) are a special class of long non-coding RNAs (lncRNAs) that can control gene expression programs on multiple levels thereby contributing to cancer progression. However, their subtype-specific expression and function as well as molecular interactions in PDAC are not fully understood yet. In this study, we systematically investigated the expression of lincRNAs in pancreatic cancer and its molecular subtypes using publicly available data from large-scale studies. We identified 27 deregulated lincRNAs that showed a significant different expression pattern in PDAC subtypes suggesting context-dependent roles. We further analyzed these lincRNAs regarding their common expression patterns. Moreover, we inferred clues on their functions based on correlation analyses and predicted interactions with RNA-binding proteins, microRNAs, and mRNAs. In summary, we identified several PDAC-associated lincRNAs of prognostic relevance and potential context-dependent functions and molecular interactions. Hence, our study provides a valuable resource for future investigations to decipher the role of lincRNAs in pancreatic cancer.

RNA Binding Proteins as Drivers and Therapeutic Target Candidates in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinomas (PDAC) belong to the most frequent and most deadly malignancies in the western world. Mutations in KRAS and TP53 along with some other frequent polymorphisms occur almost universally and are likely to be responsible for tumor initiation. However, these mutations cannot explain the heterogeneity in therapeutic responses observed in PDAC patients, which limits efficiency of current therapeutic strategies. Instead, recent classifications of PDAC tumor samples are based on transcriptomics data and thus include information about epigenetic, transcriptomic, and post-transcriptomic deregulations. RNA binding proteins (RBPs) are important post-transcriptional regulators involved in every aspect of the RNA life cycle and thus considerably influence the transcriptome. In this study, we systematically investigated deregulated expression, prognostic value, and essentiality reported for RBPs in PDAC or PDAC cancer models using publicly available data. We identified 44 RBPs with suggested oncogenic potential. These include various proteins, e.g., IGF2 mRNA binding proteins (IGF2BPs), with reported tumor-promoting roles. We further characterized these RBPs and found common patterns regarding their expression, interaction, and regulation by microRNAs. These analyses suggest four prime candidate oncogenic RBPs with partially validated target potential: APOBEC1, IGF2BP1 and 3, and OASL.

The expression profiles and prognostic values of HSPs family members in Head and neck cancer

Background

Head and neck squamous cell carcinoma (HNSC) ranks as the sixth most common malignancy. The identification of highly specific and sensitive prognostic markers and potential drug targets can contribute to enhanced patient prognosis and individualized treatments. Heat shock proteins (HSPs) act as molecular chaperones and play a crucial role in maintaining cell homeostasis. Recently, research has indicated that HSPs also act as "evil chaperones" in cancer development.

Methods

In this study, we assessed the expression of HSPs in HNSC patients using the ONCOMINE, GEPIA, and UALCAN databases. Mutations of HSP genes were also analysed using the cBioPortal database. Additionally, the expression levels of HSPs were verified using the Human Protein Altas (THPA) database.

Results

We found that the expression levels of HSPH1, HSPD1, SERPINH1, HSPA4, and HSP90AA1 were significantly higher in tissues from HNSC patients compared with normal tissues. Moreover, HSPH1, HSPD1, SERPINH1, HSPA4 and HSP90AA1 expressions were linked to disease progression. Survival analysis with the GEPIA and OncoLnc databases indicated that upregulation of HSPH1, HSPD1, SERPINH1, HSPA4 and HSP90AA1 was related to poor overall survival (OS).

Conclusion

This study suggests that the HSPH1, HSPD1, SERPINH1, HSPA4 and HSP90AA1 genes are potential clinical targets and prognostic biomarkers for patients with HNSC.

Octyl Gallate Induces Pancreatic Ductal Adenocarcinoma Cell Apoptosis and Suppresses Endothelial-Mesenchymal Transition-Promoted M2-Macrophages, HSP90α Secretion, and Tumor Growth

Octyl gallate (OG) is a common antioxidant and preservative safely used in food additive and cosmetics. In this study, OG exhibited an activity to induce apoptosis in pancreatic ductal adenocarcinoma (PDAC) cells. It induced BNIP3L level and facilitated physical associations of BNIP3L with Bcl-2 as well as Bcl-XL to set the mitochondrial Bax/Bak channels free for cytochrome c release. In addition, in vivo evaluation also showed that daily oral administration of OG was efficacious to prevent the tumor growth of PDAC cell grafts. Considering PDAC is a desmoplastic tumor consisting of many cancer-associated fibroblasts (CAFs), we further evaluated the efficacy of OG in a CAFs-involved PDAC mouse model. Endothelial-to-mesenchymal transition (EndoMT) is an important source of CAFs. The mix of EndoMT-derived CAFs with PDAC cell grafts significantly recruited myeloid-derived macrophages but prevented immune T cells. HSP90α secreted by EndoMT-derived CAFs further induced macrophage M2-polarization and more HSP90α secretion to expedite PDAC tumor growth. OG exhibited its potent efficacy against the tumor growth, M2-macrophages, and serum HSP90α level in the EndoMT-involved PDAC mouse model. CD91 and TLR4 are cell-surface receptors for extracellular HSP90α (eHSP90α). OG blocked eHSP90α-TLR4 ligation and, thus, prevented eHSP90α-induced M2-macrophages and more HSP90α secretion from macrophages and PDAC cells.

Endothelial-mesenchymal transition harnesses HSP90α-secreting M2-macrophages to exacerbate pancreatic ductal adenocarcinoma

Background

Endothelial-to-mesenchymal transition (EndoMT) can provide a source of cancer-associated fibroblasts which contribute to desmoplasia of many malignancies including pancreatic ductal adenocarcinoma (PDAC). We investigated the clinical relevance of EndoMT in PDAC, and explored its underlying mechanism and therapeutic implication.

Methods

Expression levels of 29 long non-coding RNAs were analyzed from the cells undergoing EndoMT, and an EndoMT index was proposed to survey its clinical associations in the PDAC patients of The Cancer Genome Atlas database. The observed clinical correlation was further confirmed by a mouse model inoculated with EndoMT cells-involved PDAC cell grafts. In vitro co-culture with EndoMT cells or treatment with the conditioned medium were performed to explore the underlying mechanism. Because secreted HSP90α was involved, anti-HSP90α antibody was evaluated for its inhibitory efficacy against the EndoMT-involved PDAC tumor.

Results

A combination of low expressions of LOC340340, LOC101927256, and MNX1-AS1 was used as an EndoMT index. The clinical PDAC tissues with positive EndoMT index were significantly correlated with T4-staging and showed positive for M2-macrophage index. Our mouse model and in vitro cell-culture experiments revealed that HSP90α secreted by EndoMT cells could induce macrophage M2-polarization and more HSP90α secretion to promote PDAC tumor growth. Furthermore, anti-HSP90α antibody showed a potent therapeutic efficacy against the EndoMT and M2-macrophages-involved PDAC tumor growth.

Conclusions

EndoMT cells can secrete HSP90α to harness HSP90α-overproducing M2-type macrophages to promote PDAC tumor growth, and such effect can be targeted and abolished by anti-HSP90α antibody.

Tumor-released autophagosomes induces CD4+ T cell-mediated immunosuppression via a TLR2-IL-6 cascade

BACKGROUND

CD4⁺ T cells are critical effectors of anti-tumor immunity, but how tumor cells influence CD4⁺ T cell effector function is not fully understood. Tumor cell-released autophagosomes (TRAPs) are being recognized as critical modulators of host anti-tumor immunity during tumor progression. Here, we explored the mechanistic aspects of TRAPs in the modulation of CD4⁺ T cells in the tumor microenvironment.

METHODS

TRAPs isolated from tumor cell lines and pleural effusions or ascites of cancer patients were incubated with CD4⁺ T cells to examine the function and mechanism of TRAPs in CD4⁺ T cell differentiation and function. TRAPs-elicited CD4⁺ T cells were tested for their suppression of effector T cell function, induction of regulatory B cells, and promotion of tumorigenesis and metastasis in a mouse model.

RESULTS

Heat shock protein 90α (HSP90α) on the surface of TRAPs from malignant effusions of cancer patients and tumor cell lines stimulated CD4⁺ T cell production of IL-6 via a TLR2-MyD88-NF-κB signal cascade. TRAPs-induced autocrine IL-6 further promoted CD4⁺ T cells secretion of IL-10 and IL-21 via STAT3. Notably, TRAPs-elicited CD4⁺ T cells inhibited CD4⁺ and CD8⁺ effector T cell function in an IL-6- and IL-10-dependent manner and induced IL-10-producing regulatory B cells (Bregs) via IL-6, IL-10 and IL-21, thereby promoting tumor growth and metastasis. Consistently, inhibition of tumor autophagosome formation or IL-6 secretion by CD4⁺ T cells markedly retarded tumor growth. Furthermore, B cell or CD4⁺ T cell depletion impeded tumor growth by increasing effector T cell function.

CONCLUSIONS

HSP90α on the surface of TRAPs programs the immunosuppressive functions of CD4⁺ T cells to promote tumor growth and metastasis. TRAPs or their membrane-bound HSP90α represent important therapeutic targets to reverse cancer-associated immunosuppression and improve immunotherapy.

Tumor-released autophagosomes induces CD4+ T cell-mediated immunosuppression via a TLR2-IL-6 cascade

BACKGROUND

CD4⁺ T cells are critical effectors of anti-tumor immunity, but how tumor cells influence CD4⁺ T cell effector function is not fully understood. Tumor cell-released autophagosomes (TRAPs) are being recognized as critical modulators of host anti-tumor immunity during tumor progression. Here, we explored the mechanistic aspects of TRAPs in the modulation of CD4⁺ T cells in the tumor microenvironment.

METHODS

TRAPs isolated from tumor cell lines and pleural effusions or ascites of cancer patients were incubated with CD4⁺ T cells to examine the function and mechanism of TRAPs in CD4⁺ T cell differentiation and function. TRAPs-elicited CD4⁺ T cells were tested for their suppression of effector T cell function, induction of regulatory B cells, and promotion of tumorigenesis and metastasis in a mouse model.

RESULTS

Heat shock protein 90α (HSP90α) on the surface of TRAPs from malignant effusions of cancer patients and tumor cell lines stimulated CD4⁺ T cell production of IL-6 via a TLR2-MyD88-NF-κB signal cascade. TRAPs-induced autocrine IL-6 further promoted CD4⁺ T cells secretion of IL-10 and IL-21 via STAT3. Notably, TRAPs-elicited CD4⁺ T cells inhibited CD4⁺ and CD8⁺ effector T cell function in an IL-6- and IL-10-dependent manner and induced IL-10-producing regulatory B cells (Bregs) via IL-6, IL-10 and IL-21, thereby promoting tumor growth and metastasis. Consistently, inhibition of tumor autophagosome formation or IL-6 secretion by CD4⁺ T cells markedly retarded tumor growth. Furthermore, B cell or CD4⁺ T cell depletion impeded tumor growth by increasing effector T cell function.

CONCLUSIONS

HSP90α on the surface of TRAPs programs the immunosuppressive functions of CD4⁺ T cells to promote tumor growth and metastasis. TRAPs or their membrane-bound HSP90α represent important therapeutic targets to reverse cancer-associated immunosuppression and improve immunotherapy.

Over-expression of low-density lipoprotein receptor-related Protein-1 is associated with poor prognosis and invasion in pancreatic ductal adenocarcinoma

BACKGROUND

Low-density lipoprotein receptor-Related Protein-1 (LRP-1) has been reported to involve in tumor development. However, its role in pancreatic cancer has not been elucidated. The present study was designed to evaluate the expression of LRP-1 in Pancreatic Ductal Adenocarcinoma Cancer (PDAC) as well as its association with prognosis.

METHODS

Here, 478 pancreatic cancers were screened for suitable primary PDAC tumors. The samples were analyzed using qRT-PCR, western blotting, and Immunohistochemistry (IHC) staining as well as LRP-1 expression in association with clinicopathological features.

RESULTS

The relative LRP-1 mRNA expression was up-regulated in 82.3% (42/51) of the PDAC tumors and its expression (3.72 ± 1.25) was significantly higher than that in pancreatic normal margins (1.0 ± 0.23, P < 0.05). This up-regulation was stage dependent (P < 0.05). A similar pattern of LRP-1 protein expression was discovered (P < 0.05). The high expression of LRP-1 in the PDAC tissues was strongly correlated with the low survival time (P = 0.001), TNM classification (P = 0.001), low differentiations status (P = 0.001), lymphatic invasion (P = 0.01) and Perineural Invasion (PNI) status (P = 0.001).

CONCLUSIONS

Our finding for the first time revealed that LRP-1 expression inversely associated with poor prognosis and PNI in PDAC tumor.