Caveolin-1 expression level in cancer associated fibroblasts predicts outcome in gastric cancer

Kinesin 26B modulates M2 polarization of macrophage by activating cancer-associated fibroblasts to aggravate gastric cancer occurrence and metastasis

BACKGROUND

The regulatory effects of KIF26B on gastric cancer (GC) have been confirmed, but the specific mechanism still needs further exploration. Pan-cancer analysis shows that the KIF26B expression is highly related to immune infiltration of cancer-associated fibroblasts (CAFs), and CAFs promote macrophage M2 polarization and affect cancers' progression.

AIM

To investigate the regulatory functions of KIF26B on immune and metastasis of GC.

METHODS

We analyzed genes' mRNA levels by quantitative real-time polymerase chain reaction. Expression levels of target proteins were detected by immunohistochemistry, ELISA, and Western blotting. We injected AGS cells into nude mice for the establishment of a xenograft tumor model and observed the occurrence and metastasis of GC. The degree of inflammatory infiltration in pulmonary nodes was observed through hematoxylin-eosin staining. Transwell and wound healing assays were performed for the evaluation of cell invasion and migration ability. Tube formation assay was used for detecting angiogenesis. M2-polarized macrophages were estimated by immunofluorescence and flow cytometry.

RESULTS

KIF26B was significantly overexpressed in cells and tissues of GC, and the higher expression of KIF26B was related to GC metastasis and prognosis. According to in vivo experiments, KIF26B promoted tumor formation and metastasis of GC. KIF26B expression was positively associated with CAFs' degree of infiltration. Moreover, CAFs could regulate M2-type polarization of macrophages, affecting GC cells' migration, angiogenesis, invasion, and epithelial-mesenchymal transition process.

CONCLUSION

KIF26B regulated M2 polarization of macrophage through activating CAFs, regulating the occurrence and metastasis of GC.

The anti-neoplastic effects of metformin modulate the acquired phenotype of fibroblast cells in the breast cancer-normal fibroblast co-culture system

Intracellular communications between breast cancer and fibroblast cells were reported to be involved in cancer proliferation, growth, and therapy resistance. The hallmarks of cancer-fibroblast interactions, consisting of caveolin 1 (Cav1) and mono-carboxylate transporter 4 (MCT4) (metabolic coupling markers), along with IL-6, TGFβ, and lactate secretion, are considered robust biomarkers predicting recurrence and metastasis. In order to promote a novel phenotype in normal fibroblasts, we predicted that breast cancer cells could be able to cause loss of Cav1 and increase of MCT4, as well as elevate IL-6 and TGFβ in nearby normal fibroblasts. We created a co-culture model using breast cancer (4T1) and normal fibroblast (NIH3T3) cell lines cultured under specific experimental conditions in order to directly test our theory. Moreover, we show that long-term co-culture of breast cancer cells and normal fibroblasts promotes loss of Cav1 and gain of MCT4 in adjacent fibroblasts and increase lactate secretion. These results were validated using the monoculture of each group separately as a control. In this system, we show that metformin inhibits IL-6 and TGFβ secretion and re-expresses Cav1 in both cells. However, MCT4 and lactate stayed high after treatment with metformin. In conclusion, our work shows that co-culture with breast cancer cells may cause significant alterations in the phenotype and secretion of normal fibroblasts. Metformin, however, may change this state and affect fibroblasts' acquired phenotypes. Moreover, mitochondrial inhibition by metformin after 8 days of treatment, significantly hinders tumor growth in mouse model of breast cancer.

Caveolin-1 protein expression as a prognostic biomarker of gastrointestinal tumours: A systematic review and meta-analysis

BACKGROUND

Gastrointestinal (GI) cancers remain a major threat worldwide, accounting for over 30% of cancer deaths. The identification of novel prognostic biomarkers remains a challenge despite significant advances in the field. The CAV1 gene, encoding the caveolin-1 protein, remains enigmatic in cancer and carcinogenesis, as it has been proposed to act as both a tumour promoter and a tumour suppressor.

METHODS

To analyse the differential role of caveolin-1 expression in both tumour cells and stroma in relation to prognosis in GI tumours, we performed a systematic review and meta-analysis according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines; PROSPERO registration number: CRD42022299148.

RESULTS

Our analysis showed that high levels of caveolin-1 in tumour cells were associated with poor prognosis and inferior overall survival (OS) in oesophageal and pancreatic cancer and hepatocellular carcinoma (HCC), but not in gastric and colorectal cancer. Importantly, our study showed that higher stromal caveolin-1 expression was associated with significantly longer OS and disease-free survival in colorectal cancer. Analysis of stromal caveolin-1 expression in the remaining tumours showed a similar trend, although it did not reach statistical significance.

CONCLUSIONS

The data suggest that caveolin-1 expression in the tumour cells of oesophageal, pancreatic cancer and HCC and in the stroma of colorectal cancer may be an important novel predictive biomarker for the clinical management of these diseases in a curative setting. However, the main conclusion of our analysis is that caveolin-1 expression should always be assessed separately in stroma and tumour cells.

Unraveling the Cave: A Seventy-Year Journey into the Caveolar Network, Cellular Signaling, and Human Disease

In the mid-1950s, a groundbreaking discovery revealed the fascinating presence of caveolae, referred to as flask-shaped invaginations of the plasma membrane, sparking renewed excitement in the field of cell biology. Caveolae are small, flask-shaped invaginations in the cell membrane that play crucial roles in diverse cellular processes, including endocytosis, lipid homeostasis, and signal transduction. The structural stability and functionality of these specialized membrane microdomains are attributed to the coordinated activity of scaffolding proteins, including caveolins and cavins. While caveolae and caveolins have been long appreciated for their integral roles in cellular physiology, the accumulating scientific evidence throughout the years reaffirms their association with a broad spectrum of human disorders. This review article aims to offer a thorough account of the historical advancements in caveolae research, spanning from their initial discovery to the recognition of caveolin family proteins and their intricate contributions to cellular functions. Furthermore, it will examine the consequences of a dysfunctional caveolar network in the development of human diseases.

What is new in cancer-associated fibroblast biomarkers?

The tumor microenvironment is one of the important drivers of tumor development. Cancer-associated fibroblasts (CAFs) are a major component of the tumor stroma and actively participate in tumor development, invasion, metastasis, drug resistance, and other biological behaviors. CAFs are a highly heterogeneous group of cells, a reflection of the diversity of their origin, biomarkers, and functions. The diversity of CAF origin determines the complexity of CAF biomarkers, and CAF subpopulations expressing different biomarkers may play contrasting roles in tumor progression. In this review, we provide an overview of these emerging CAF biomarkers and the biological functions that they suggest, which may give a better understanding of the relationship between CAFs and tumor cells and be of great significance for breakthroughs in precision targeted therapy for tumors. Video Abstract.

Perturbing plasma membrane lipid: a new paradigm for tumor nanotherapeutics

Cancer is generally considered a result of genetic mutations that cause epigenetic changes, leading to anomalous cellular behavior. Since 1970s, an increasing understanding of the plasma membrane and specifically the lipid alterations in tumor cells have provided novel insights for cancer therapy. Moreover, the advances in nanotechnology offer a potential opportunity to target the tumor plasma membrane while minimizing side effects on normal cells. To further develop membrane lipid perturbing tumor therapy, the first section of this review demonstrates the association between plasma membrane physicochemical properties and tumor signaling, metastasis, and drug resistance. The second section highlights existing nanotherapeutic strategies for membrane disruption, including lipid peroxide accumulation, cholesterol regulation, membrane structure disruption, lipid raft immobilization, and energy-mediated plasma membrane perturbation. Finally, the third section evaluates the prospects and challenges of plasma membrane lipid perturbing therapy as a therapeutic strategy for cancers. The reviewed membrane lipid perturbing tumor therapy strategies are expected to bring about necessary changes in tumor therapy in the coming decades.

The Tumor Microenvironment in Tumorigenesis and Therapy Resistance Revisited

Tumorigenesis is a complex and dynamic process involving cell-cell and cell-extracellular matrix (ECM) interactions that allow tumor cell growth, drug resistance and metastasis. This review provides an updated summary of the role played by the tumor microenvironment (TME) components and hypoxia in tumorigenesis, and highlight various ways through which tumor cells reprogram normal cells into phenotypes that are pro-tumorigenic, including cancer associated- fibroblasts, -macrophages and -endothelial cells. Tumor cells secrete numerous factors leading to the transformation of a previously anti-tumorigenic environment into a pro-tumorigenic environment. Once formed, solid tumors continue to interact with various stromal cells, including local and infiltrating fibroblasts, macrophages, mesenchymal stem cells, endothelial cells, pericytes, and secreted factors and the ECM within the tumor microenvironment (TME). The TME is key to tumorigenesis, drug response and treatment outcome. Importantly, stromal cells and secreted factors can initially be anti-tumorigenic, but over time promote tumorigenesis and induce therapy resistance. To counter hypoxia, increased angiogenesis leads to the formation of new vascular networks in order to actively promote and sustain tumor growth via the supply of oxygen and nutrients, whilst removing metabolic waste. Angiogenic vascular network formation aid in tumor cell metastatic dissemination. Successful tumor treatment and novel drug development require the identification and therapeutic targeting of pro-tumorigenic components of the TME including cancer-associated- fibroblasts (CAFs) and -macrophages (CAMs), hypoxia, blocking ECM-receptor interactions, in addition to the targeting of tumor cells. The reprogramming of stromal cells and the immune response to be anti-tumorigenic is key to therapeutic success. Lastly, this review highlights potential TME- and hypoxia-centered therapies under investigation.

The role of cancer-associated fibroblasts in tumorigenesis of gastric cancer

Despite advances in anticancer therapy, the prognosis of gastric cancer (GC) remains unsatisfactory. Research in recent years has shown that the malignant behavior of cancer is not only attributable to tumor cells but is partly mediated by the activity of the cancer stroma and controlled by various molecular networks in the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are one of the most abundant mesenchymal cell components of the stroma and extensively participate in the malignant development of GC malignancy. CAFs modulate the biological properties of tumor cells in multiple ways, including the secretion of various bioactive molecules that have effects through paracrine and autocrine signaling, the release of exosomes, and direct interactions, thereby affecting GC initiation and development. However, there is marked heterogeneity in the cellular origins, phenotypes, and functions of CAFs in the TME of GC. Furthermore, variations in factors, such as proteins, microRNAs, and lncRNAs, affect interactions between CAFs and GC cells, although, the potential molecular mechanisms are still poorly understood. In this review, we aim to describe the current knowledge of the cellular features and heterogeneity of CAFs and discuss how these factors are regulated in CAFs, with a focus on how they affect GC biology. This review provides mechanistic insight that could inform therapeutic strategies and improve the prognosis of GC patients.

Different clinical significance of novel B7 family checkpoints VISTA and HHLA2 in human lung adenocarcinoma

Background: VISTA and HHLA2 are two recently identified members of the B7 homologue family of immune-regulatory molecules. But the expression patterns and clinical significance of VISTA and HHLA2 in lung adenocarcinoma (LUAD) remain largely unknown. Methods: Immunohistochemistry was performed to examine the expression of VISTA, HHLA2, PD-L1 and CD8⁺ tumor-infiltrating lymphocytes in 74 cases of LUAD. The expression of VISTA, HHLA2, PD-L1, CD68 and CD8 proteins was detected by multiplex immunofluorescence staining in the LUAD tissues. Results: High expression of VISTA and HHLA2 was observed in LUAD compared with noncancerous tissues. High VISTA expression in immune cells predicted a high mortality rate and worse survival. Conclusion: VISTA and HHLA2 are potential immunotherapeutic targets that possess different prognostic significance in LUAD.

Prognostic significance and therapeutic implications of Caveolin-1 in gastrointestinal tract malignancies

Caveolin-1 (CAV1) is expressed in several solid tumors both in cancerous cells as well as in tumor stroma and is reported to be related to cancer progression, metastasis, therapy resistance and clinical outcomes. Many studies report contrasting functions of this protein depending on the tumor cell model, the tumor type, or the stage of cancer studied. This protein is reported to function both as tumor suppressor and as tumor promoter. In this review, we aim to summarize translational and clinical studies that provide evidence of the role of CAV1 in tumor progression and survival outcome focusing on tumors of the gastrointestinal (GI) tract. Towards this aim, a detailed search has been performed for studies on the expression and the role of CAV1 in oesophageal, gastric, colorectal, pancreatic cancer and cholangiocarcinoma prognosis. We also review and discuss the implication of CAV1 in the outcome of pharmacological interventions. We conclude that CAV1 has the potential to become an important prognostic, and possibly predictive, biomarker in GI malignancies. It may also become a novel target towards the development of improved cancer therapies. However, it is obvious that there remains a lack of consensus on important issues such as the methodologies and cut-off levels in caveolin assessment. This ultimately result in many studies being contradictory not only in terms of the role of CAV1 as a tumor-promoting or suppressing gene but also in terms of the tumor compartment in which the levels of this protein may be of clinical significance. Addressing these important technical issues, in conjunction with a further elucidation of the role of CAV1 in tumor formation and progression, will delineate the importance of CAV1 in prognostic and therapeutic perspectives.

The role of caveolin-1 in the biofate and efficacy of anti-tumor drugs and their nano-drug delivery systems

As one of the most important components of caveolae, caveolin-1 is involved in caveolae-mediated endocytosis and transcytosis pathways, and also plays a role in regulating the cell membrane cholesterol homeostasis and mediating signal transduction. In recent years, the relationship between the expression level of caveolin-1 in the tumor microenvironment and the prognostic effect of tumor treatment and drug treatment resistance has also been widely explored. In addition, the interplay between caveolin-1 and nano-drugs is bidirectional. Caveolin-1 could determine the intracellular biofate of specific nano-drugs, preventing from lysosomal degradation, and facilitate them penetrate into deeper site of tumors by transcytosis; while some nanocarriers could also affect caveolin-1 levels in tumor cells, thereby changing certain biophysical function of cells. This article reviews the role of caveolin-1 in tumor prognosis, chemotherapeutic drug resistance, antibody drug sensitivity, and nano-drug delivery, providing a reference for the further application of caveolin-1 in nano-drug delivery systems.

Differences in the expression of caveolin-1 isoforms in cancer-associated and normal fibroblasts of patients with oral squamous cell carcinoma

OBJECTIVES

For many years, tumor development has been viewed as a cell-autonomous process; however, today we know that the tumor microenvironment (TME) and especially cancer-associated fibroblasts (CAFs) significantly contribute to tumor progression. Caveolin-1 (Cav-1) is a scaffolding protein which is involved in several cancer-associated processes as important component of the caveolae. Our goal was to shed light on the expression of the two different isoforms of Cav-1 in normal fibroblasts (NFs) and CAFs of patients with oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

Fibroblasts from normal mucosa and CAFs were isolated and propagated in vitro. Gene expression of the different Cav-1 isoforms was assessed via quantitative real-time PCR (qPCR) and supplemented by protein expression analysis.

RESULTS

We could show that the Cav-1β isoform is more highly expressed in NFs and CAFs compared to Cav-1α. Furthermore, the different Cav-1 isoforms tended to be differently expressed in different tumor stages. However, this trend could not be seen consistently, which is in line with the ambiguous role of Cav-1 in tumor progression described in literature. Western blotting furthermore revealed that NFs and CAFs might differ in the oligomerization profile of the Cav-1 protein.

CONCLUSION

These differences in expression of Cav-1 between NFs and CAFs of patients with OSCC confirm that the protein might play a role in tumor progression and is of interest for further analyses.

CLINICAL RELEVANCE

Our findings support a possible role of the two isoforms of Cav-1 in the malignant transformation of OSCC.

Caveolae as Potential Hijackable Gates in Cell Communication

Caveolae are membrane microdomains described in many cell types involved in endocytocis, transcytosis, cell signaling, mechanotransduction, and aging. They are found at the interface with the extracellular environment and are structured by caveolin and cavin proteins. Caveolae and caveolins mediate transduction of chemical messages via signaling pathways, as well as non-chemical messages, such as stretching or shear stress. Various pathogens or signals can hijack these gates, leading to infectious, oncogenic and even caveolin-related diseases named caveolinopathies. By contrast, preclinical and clinical research have fallen behind in their attempts to hijack caveolae and caveolins for therapeutic purposes. Caveolae involvement in human disease is not yet fully explored or understood and, of all their scaffold proteins, only caveolin-1 is being considered in clinical trials as a possible biomarker of disease. This review briefly summarizes current knowledge about caveolae cell signaling and raises the hypothesis whether these microdomains could serve as hijackable “gatekeepers” or “gateways” in cell communication. Furthermore, because cell signaling is one of the most dynamic domains in translating data from basic to clinical research, we pay special attention to translation of caveolae, caveolin, and cavin research into clinical practice.

Clinicopathological and prognostic significance of caveolin-1 and ATG4C expression in the epithelial ovarian cancer

Objective

Altered expression of caveolin-1 (CAV1) and autophagy marker ATG4C is observed in various types of human cancers. However, the clinical significance of CAV1 and ATG4C expression in epithelial ovarian cancer (EOC) remains largely unknown. The present study aims to explore the clinicopathological value and prognostic significance of CAV1 and ATG4C expression in EOC.

Methods

The expression pattern and prognostic value of CAV1 and ATG4C mRNA in EOC were analyzed using data from the Cancer Genome Atlas (TCGA) database (N = 373). In addition, immunohistochemistry analysis was performed to detect and assay the expression of CAV1 and ATG4C proteins in tissue microarray of EOC.

Results

Based on TCGA data, Kaplan-Meier analysis indicated that patients with low CAV1 mRNA (p = 0.021) and high ATG4C mRNA (p = 0.018) expression had a significantly shorter overall survival (OS). Cox regression analysis demonstrated that the expression levels of CAV1 (p = 0.023) and ATG4C mRNA (p = 0.040) were independent prognostic factors for OS in EOC. In addition, the Concordance Index of the nomogram for OS prediction was 0.660. Immunohistochemical analysis showed the expression levels of stromal CAV1 and cancerous ATG4C proteins, and high expression of both CAV1 and ATG4C protein in the stroma were found to significantly correlate with the histologic subtypes of EOC, especially with serous subtype.

Conclusions

Decreased expression of CAV1 mRNA and increased expression of ATG4C mRNA in EOC can predict poor overall survival. The expression levels of CAV1 protein in stromal cells and ATG4C protein in cancer cells are significantly associated with histologic subtypes of EOC. These findings suggest that CAV1 and ATG4C serve as useful prognostic biomarkers and candidate therapeutic targets in EOC.

Metabolic reprogramming of normal oral fibroblasts correlated with increased glycolytic metabolism of oral squamous cell carcinoma and precedes their activation into carcinoma associated fibroblasts

Cancers show a metabolic shift towards aerobic glycolysis. By "corrupting" their microenvironment, carcinoma cells are able to obtain energy substrates to "fuel" their mitochondrial metabolism and cell growth in an autophagy-associated, paracrine manner. However, the metabolic changes and role of normal fibroblasts in this process remain unclear. We devised a novel, indirect co-culture system to elucidate the mechanisms of metabolic coupling between stromal cells and oral squamous cell carcinoma (OSCC) cells. Here, we showed that normal oral fibroblasts (NOFs) and OSCC become metabolically coupled through several processes before acquiring an activated phenotype and without inducing senescence. We observed, for the first time, that NOFs export mitochondria towards OSCCs through both direct contact and via indirect mechanisms. NOFs are activated and are able to acquire a cancer-associated fibroblasts metabolic phenotype when co-cultivation with OSSC cells, by undergoing aerobic glycolysis, secreting more reactive oxygen species (ROS), high L-lactate and overexpressing lactate exporter MCT-4, leading to mitochondrial permeability transition pore (mPTP) opening, hypoxia, and mitophagy. On the other hand, Cav-1-low NOFs generate L-lactate to "fuel" mitochondrial metabolism and anabolic growth of OSCC. Most interestingly, the decrease in AMPK activity and PGC-1α expression might involve in regulation of ROS that functions to maintain final energy and metabolic homeostasis. This indicated, for the first time, the existence of ATP and ROS homeostasis during carcinogenesis. Our study suggests that an efficient therapeutical approach has to target the multiple mechanisms used by them to corrupt the normal surrounding stroma and metabolic homeostasis.

Silencing of caveolin-1 in fibroblasts as opposed to epithelial tumor cells results in increased tumor growth rate and chemoresistance in a human pancreatic cancer model

Caveolin-1 (Cav-1) expression has been shown to be associated with tumor growth and resistance to chemotherapy in pancreatic cancer. The primary aim of this study was to explore the significance of Cav-1 expression in pancreatic cancer cells as compared to fibroblasts in relation to cancer cell proliferation and chemoresistance, both in vitro and in vivo, in an immunodeficient mouse model. We also aimed to evaluate the immunohistochemical expression of Cav-1 in the epithelial and stromal component of pancreatic cancer tissue specimens. The immunohistochemical staining of poorly differentiated tissue sections revealed a strong and weak Cav-1 expression in the epithelial tumor cells and stromal fibroblasts, respectively. Conversely, the well-differentiated areas were characterized by a weak epithelial Cav-1 expression. Cav-1 downregulation in cancer cells resulted in an increased proliferation in vitro; however, it had no effect on chemoresistance and growth gain in vivo. By contrast, the decreased expression of Cav-1 in fibroblasts resulted in a growth advantage and the chemo-resistance of cancer cells when they were co-injected into immunodeficient mice to develop mixed fibroblast/cancer cell xenografts. On the whole, the findings of this study suggest that the downregulation of Cav-1 in fibroblasts is associated with an increased tumor proliferation rate in vivo and chemoresistance. Further studies are warranted to explore whether the targeting of Cav-1 in the stroma may represent a novel therapeutic approach in pancreatic cancer.

Autophagy in cancer: a complex relationship

Macroautophagy is the process by which cells package and degrade cytosolic components, and recycle the breakdown products for future use. Since its initial description by Christian de Duve in the 1960s, significant progress has been made in understanding the mechanisms that underlie this vital cellular process and its specificity. Furthermore, macroautophagy is linked to pathologic conditions such as cancer and is being studied as a therapeutic target. In this review, we will explore the connections between autophagy and cancer, which are tumor- and context-dependent and include the tumor microenvironment. We will highlight the importance of tumor compartment-specific autophagy in both cancer aggressiveness and treatment.

Antitumor necrosis factor-α antibodies as a noveltherapy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) accounts for many cases of cancer-associated mortality. Tumor necrosis factor (TNF)-α is a key mediator of tumor-promoting inflammation. It has been demonstrated that anti-TNF-α treatments have preclinical benefits for multiple types of cancer, however their potential for treating HCC remains unclear. Through fluorescence-activated cell sorter analysis and enzyme-linked immunosorbent assay, the results of the current study indicated that TNF-α was strongly expressed in HCC tissues and the HCC cell lines HepG2 and Hep3B. In vitro, anti-TNF-α antibodies (infliximab and etanercept) decreased HCC cell viability via antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity effects. Infliximab treatment also significantly increased apoptosis in HepG2 and Hep3B cells compared with controls (P<0.001 and P<0.05, respectively). In vivo, anti-TNF-α treatment delayed HCC progression as indicated by the significantly prolonged survival time in an HCC xenograft mouse model (P=0.0009). Further analyses revealed that anti-TNF-α treatment significantly decreased the expression of pro-inflammatory cytokines, including TNF-α (P<0.01), interleukin (IL)-1β (P<0.05), IL-6 (P<0.05) and IL-17 (P<0.05) and induced apoptosis in HCC tumors. The results of the current study suggest that TNF-α is a potential target for novel therapeutic strategies to treat HCC. Anti-TNF-α treatments compromised HCC tumor progression by inducing cell death and decreasing levels of pro-inflammatory cytokines.

Stromal Caveolin-1 and Caveolin-2 Expression in Primary Tumors and Lymph Node Metastases

The expression of caveolin-1 (CAV1) in both tumor cell and cancer-associated fibroblasts (CAFs) has been found to correlate with tumor aggressiveness in different epithelial tumor entities, whereas less is known for caveolin-2 (CAV2). The aim of this study was to investigate the clinicopathological significance and prognostic value of stromal CAV1 and CAV2 expression in lung cancer. The expression of these two genes was investigated at protein level on a tissue microarray (TMA) consisting of 161 primary tumor samples. 50.7% of squamous cell lung cancer (SCC) tumors showed strong expression of CAV1 in the tumor-associated stromal cells, whereas only 15.1% of adenocarcinomas (AC) showed a strong CAV1 expression (p < 0.01). A strong CAV2 stromal expression was found in 46.0% of the lung tumor specimens, with no significant difference between the subtypes. Neither CAV1 nor CAV2 stromal expression was associated with any other clinicopathological factor including survival. When the stromal expression in matched primary tumors and lymph node metastases was compared, both CAV1 and CAV2 expressions were frequently found lost in the corresponding stroma of the lymph node metastasis (40.6%, p = 0.003 and 38.4%, p = 0.001, resp.). Loss of stromal CAV2 in the lymph node metastases was also significantly associated with earlier death (p = 0.011). In conclusion, in contrast to the expression patterns in the tumor tissue of lung cancer, stromal expression of CAV1 in primary tumors was not associated with clinical outcome whereas the stromal expression of especially CAV2 in the metastatic lymph nodes could be associated with lung cancer pathogenesis.

Caveolin-1, cancer and therapy resistance

Resistance of solid tumors to chemo- and radiotherapy remains a major obstacle in anti-cancer treatment. Herein, the membrane protein caveolin-1 (CAV1) came into focus as it is highly expressed in many tumors and high CAV1 levels were correlated with tumor progression, invasion and metastasis, and thus a worse clinical outcome. Increasing evidence further indicates that the heterogeneous tumor microenvironment, also known as the tumor stroma, contributes to therapy resistance resulting in poor clinical outcome. Again, CAV1 seems to play an important role in modulating tumor host interactions by promoting tumor growth, metastasis, therapy resistance and cell survival. However, the mechanisms driving stroma-mediated tumor growth and radiation resistance remain to be clarified. Understanding these interactions and thus, targeting CAV1 may offer a novel strategy for preventing cancer therapy resistance and improving clinical outcomes. In this review, we will summarize the resistance-promoting effects of CAV1 in tumors, and emphasize its role in the tumor-stroma communication as well as the resulting malignant phenotype of epithelial tumors.

Caveolin-1-Knockout Mouse as a Model of Inflammatory Diseases

Caveolin-1 (CAV1) is the scaffold protein of caveolae, which are minute invaginations of the cell membrane that are involved in endocytosis, cell signaling, and endothelial-mediated inflammation. CAV1 has also been reported to have a dual role as either a tumor suppressor or tumor promoter, depending on the type of cancer. Inflammation is an important player in tumor progression, but the role of caveolin-1 in generating an inflammatory milieu remains poorly characterized. We used a caveolin-1-knockout (CAV1^-/-) mouse model to assess the inflammatory status via the quantification of the pro- and anti-inflammatory cytokine levels, as well as the ability of circulating lymphocytes to respond to nonspecific stimuli by producing cytokines. Here, we report that the CAV1^-/- mice were characterized by a low-grade systemic proinflammatory status, with a moderate increase in the IL-6, TNF-α, and IL-12p70 levels. CAV1^-/- circulating lymphocytes were more prone to cytokine production upon nonspecific stimulation than the wild-type lymphocytes. These results show that CAV1 involvement in cell homeostasis is more complex than previously revealed, as it plays a role in the inflammatory process. These findings indicate that the CAV1^-/- mouse model could prove to be a useful tool for inflammation-related studies.

Metformin Effects on Metabolic Coupling and Tumor Growth in Oral Cavity Squamous Cell Carcinoma Coinjection Xenografts

Objective Many aggressive head and neck cancers contain 2 metabolically coupled tumor compartments: a glycolytic stromal compartment with low caveolin-1 (CAV1) and high monocarboxylate transporter 4 (MCT4) expression and a highly proliferative carcinoma cell compartment with high MCT1. Metabolites are shuttled by MCTs from stroma to carcinoma to fuel tumor growth. We studied the effect of carcinoma-fibroblast coinjection and metformin administration on a mouse model of head and neck squamous cell carcinoma. Study Design Xenograft head and neck squamous cell carcinoma model. Setting Basic science laboratory. Subjects and Methods Oral cavity carcinoma cells were injected alone or as coinjection with human fibroblasts into nude mice to generate xenograft tumors. Tumors were excised and stained with immunohistochemistry for markers of metabolic coupling and apoptosis, including MCT1, MCT4, CAV1, and TUNEL assay (terminal deoxynucleotidyl transferase nick end labeling). Strength of staining was assessed by a pathologist or computer-assisted pathology software. Metformin was administered orally to mice to test effects on immunohistochemical markers in xenografts. Results Coinjection tumors were 2.8-fold larger ( P = .048) and had 1.4-fold stronger MCT1 staining ( P = .016) than tumors from homotypic carcinoma cell injection. Metformin decreased the size of coinjection xenograft tumors by 45% ( P = .025). Metformin reduced MCT1 staining by 28% ( P = .05) and increased carcinoma cell apoptosis 1.8-fold as marked by TUNEL assay ( P = .005). Metformin did not have a significant effect on tumor size when CAV1 knockdown fibroblasts were used in coinjection. Conclusion Coinjection with fibroblasts increases tumor growth and metabolic coupling in oral cavity cancer xenografts. Fibroblast CAV1 expression is required for metformin to disrupt metabolic coupling and decrease xenograft size.

All-trans retinoic acid inhibits the proliferation of SGC7901 cells by regulating caveolin-1 localization via the ERK/MAPK signaling pathway

Caveolin-1 is a scaffold protein of caveolae in the mucosa of the gastrointestinal tract and acts as a tumor modulator by interacting with cell adhesion molecules and signaling receptors. Caveolin-1 stabilizes cell-cell and cell-matrix contacts and is a hallmark of a number of different types of human cancer, including gastric cancer. All-trans retinoic acid (ATRA), a derivative of vitamin A, has been demonstrated to exhibit tumor inhibitory effects in acute leukemia and certain types of solid tumor. In the present study, treatment with ATRA was demonstrated to inhibit the proliferation of gastric cancer cell line SGC7901, in a time- and dose-dependent manner. The markedly increased membrane localization of caveolin-1 was observed in the cells that were treated with 10 µmol/l ATRA for > 48 h. In addition, it was observed that treatment with ATRA was able to regulate the level of phosphorylation of extracellular signal-regulated kinase (ERK). Therefore, the SGC7901 cells were treated with a specific agonist of ERK/mitogen-activated protein kinase (MAPK) investigate whether ATRA mediated its effects via the ERK/MAPK signaling pathway. The results of the present study demonstrated that ATRA-induced increase in membrane localization of caveolin-1 was reversed by treatment with a specific agonist of ERK/MAPK. Together, these results suggest that ATRA exhibits anti-gastric cancer effects. ATRA may regulate the membrane localization of caveolin-1 in order to inhibit the proliferation of SGC7901 cells. These effects of ATRA may be mediated by inhibiting the activation of ERK/MAPK signaling pathway. These results contribute to the current knowledge on the potential use of ATRA as therapy for solid tumors and provide further insight into the potential molecular mechanisms of ATRA action.

Bidirectional alteration of Cav-1 expression is associated with mitogenic conversion of its function in gastric tumor progression

Background

Expression of caveolin-1 (Cav-1) is frequently altered in many human cancers and both tumor suppression and promotion functions of Cav-1 have been suggested based on its expression status. However, it remains unanswered how Cav-1 provokes opposite effects in different cancers or different phases of tumor progression.

Methods

To explore the implication of Cav-1 alteration in gastric tumorigenesis, the expression and mutational status of Cav-1 and its effects on tumor cell growth were characterized.

Results

A substantial fraction of primary tumors and cell lines displayed abnormally low or high Cav-1 mRNA expression, indicating the bidirectional alteration of Cav-1 in gastric cancers. While allelic imbalance and mutational alterations of the Cav-1 gene were rarely detected, aberrant promoter hyper- or hypo-methylation showed a tight correlation with bidirectional alteration of its expression. Abnormally low and high Cav-1 expression was more frequently observed in early and advanced cancers, respectively, suggesting the oncogenic switch of its function in tumor progression. Cell cycle progression, DNA synthesis, and colony forming ability were markedly decreased by Cav-1 transfection in low-expressing tumor cells but by its depletion in high-expressing cells. Interestingly, Cav-1 exerted opposite effects on MEK-ERK signaling in these two cell types through the reciprocal regulation of the RAF-ERK negative feedback loop. A feedback inhibition of RAF by ERK was stimulated by restoration of Cav-1 expression in low-expressing cells but by it depletion in high-expressing cells. As predicted, the opposite effects of Cav-1 on both tumor cell growth and inhibitory RAF phosphorylation were abolished if ERK is depleted.

Conclusion

Bidirectional alteration of Cav-1 is linked to its opposite effects on gastric tumor cell growth, which stem from the reciprocal control on the RAF-ERK negative feedback loop.

Quantitative proteomic Analysis Reveals up-regulation of caveolin-1 in FOXP3-overexpressed human gastric cancer cells

Forkhead box protein 3 (FOXP3) is implicated in tumor progression and prognosis in various types of tumor cells. We have recently reported that FOXP3 inhibited proliferation of gastric cancer (GC) cells through activating the apoptotic signaling pathway. In this study, we found that over-expression of FOXP3 inhibited GC cell migration, invasion and proliferation. Then, the label-free quantitative proteomic approach was employed to further investigating the down-stream proteins regulated by FOXP3, resulting in a total of 3,978 proteins quantified, including 186 significantly changed proteins. Caveolin-1 (CAV1), as a main constituent protein of caveolae, was one of those changed proteins up-regulated in FOXP3-overexpressed GC cells, moreover, it was assigned as one of the node proteins in the protein-protein interaction network and the key protein involved in focal adhesion pathway by bioinformatics analysis. Further biological experiments confirmed that FOXP3 directly bound to the promoter regions of CAV1 to positively regulate CAV1 transcription in GC cells. In summary, our study suggested that FOXP3 can be considered as a tumor suppressor in GC via positively regulating CAV1 through transcriptional activation, and this FOXP3-CAV1 transcriptional regulation axis may play an important role in inhibiting invasion and metastasis of GC cells. Data are available via ProteomeXchange under identifier PXD007725.

Metabolic coupling and the Reverse Warburg Effect in cancer: Implications for novel biomarker and anticancer agent development

Glucose is a key metabolite used by cancer cells to generate ATP, maintain redox state and create biomass. Glucose can be catabolized to lactate in the cytoplasm, which is termed glycolysis, or alternatively can be catabolized to carbon dioxide and water in the mitochondria via oxidative phosphorylation. Metabolic heterogeneity exists in a subset of human tumors, with some cells maintaining a glycolytic phenotype while others predominantly utilize oxidative phosphorylation. Cells within tumors interact metabolically with transfer of catabolites from supporting stromal cells to adjacent cancer cells. The Reverse Warburg Effect describes when glycolysis in the cancer-associated stroma metabolically supports adjacent cancer cells. This catabolite transfer, which induces stromal-cancer metabolic coupling, allows cancer cells to generate ATP, increase proliferation, and reduce cell death. Catabolites implicated in metabolic coupling include the monocarboxylates lactate, pyruvate, and ketone bodies. Monocarboxylate transporters (MCT) are critically necessary for release and uptake of these catabolites. MCT4 is involved in the release of monocarboxylates from cells, is regulated by catabolic transcription factors such as hypoxia inducible factor 1 alpha (HIF1A) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and is highly expressed in cancer-associated fibroblasts. Conversely, MCT1 is predominantly involved in the uptake of these catabolites and is highly expressed in a subgroup of cancer cells. MYC and TIGAR, which are genes involved in cellular proliferation and anabolism, are inducers of MCT1. Profiling human tumors on the basis of an altered redox balance and intra-tumoral metabolic interactions may have important biomarker and therapeutic implications. Alterations in the redox state and mitochondrial function of cells can induce metabolic coupling. Hence, there is interest in redox and metabolic modulators as anticancer agents. Also, markers of metabolic coupling have been associated with poor outcomes in numerous human malignancies and may be useful prognostic and predictive biomarkers.

Proteomics profiling identifies induction of caveolin-1 in chronic lymphocytic leukemia cells by bone marrow stromal cells

Chronic lymphocytic leukemia (CLL) is an indolent B-cell malignancy in which cells reside in bone marrow, lymph nodes, and peripheral blood, each of which provides a unique microenvironment. Although the levels of certain proteins are reported to induce, changes in the CLL cell proteome in the presence of bone marrow stromal cells have not been elucidated. Reverse-phase protein array analysis of CLL cells before and 24 h after stromal cell interaction revealed changed levels of proteins that regulate cell cycle, gene transcription, and protein translation. The most hit with respect to both the extent of change in expression level and statistical significance was caveolin-1, which was confirmed with immunoblotting. Caveolin-1 mRNA levels were also upregulated in CLL cells after stromal cell interaction. The induction of caveolin-1 levels was rapid and occurred as early as 1 h. Studies to determine the significance of upregulated caveolin-1 levels in CLL lymphocytes are warranted.

Down-regulation of KLF5 in cancer-associated fibroblasts inhibit gastric cancer cells progression by CCL5/CCR5 axis

It was well known that cancer-associated fibroblasts (CAFs) were an essential factor in tumor progression. However, the actual mechanism of stromal fibroblasts activation and tumor promoting effects remain unclear. Here, we showed that KLF5 expression was more frequently observed in gastric cancer-associated fibroblasts compared with normal mucosal fibroblasts. Moreover, KLF5 expression in tumor stroma was closely associated with clinicopathological features such as tumor size, invasion depth, cell grade and lymph node metastasis, as well as poor prognosis in patients with gastric cancer. In addition, we further demonstrated that KLF5-regulating CAFs affect gastric cancer cells progression by CCL5 secretion and activation of CCR5. Taken together, we concluded that KLF5 expression in gastric cancer-associated fibroblasts contribute to poor survival and promote cancer cells progression by activation of CCL5/CCR5 axis, which suggesting that KLF5 in CAFs might be considered as a promising target for the treatment of gastric cancer.

High expression of monocarboxylate transporter 4 predicts poor prognosis in patients with lung adenocarcinoma

Monocarboxylate transporter 4 (MCT-4) serves a key function in transporting lactate across the plasma membrane in various types of human cancer. Evidence indicates that MCT-4 expression is associated with non-small cell lung cancer; however, the distribution and clinical significance of MCT-4 in the lung adenocarcinoma (AC) subtype remain unknown. Thus, the aim of the present study was to explore the clinicopathological significance and prognostic values of MCT-4 expression in lung AC. Quantum dots-based immunofluorescence histochemistry was performed to observe the expression of MCT-4 in 146 specimens of lung AC and corresponding normal lung tissues. MCT-4 protein and mRNA were detected by western blotting and reverse transcription-quantitative polymerase chain reaction from 30 fresh samples of lung AC and corresponding normal lung tissues. Of the 146 samples, 25 (17.1%) exhibited high and 121 (82.9%) exhibited low MCT-4 expression. MCT-4, at the protein and mRNA level, was significantly increased in tumor specimens compared with corresponding normal lung tissue (P<0.05). MCT-4 protein expression was significantly associated with depth of invasion (P=0.034). A survival curve analysis indicated that high MCT-4 expression in lung AC was associated with a decreased overall survival rate (P=0.001). Multivariate analysis demonstrated that high MCT-4 level was an independent prognostic factor (hazard ratio, 3.192; 95% confidence interval, 1.804–5.646; P=0.001) for patients with lung AC. The results have demonstrated that high MCT-4 expression is significantly associated with the poor prognosis and disease progression of patients with lung AC. Therefore, MCT-4 may be a candidate therapeutic target in lung AC.

Prognostic Value of Metastatic Tumoral Caveolin-1 Expression in Patients with Resected Gastric Cancer

OBJECTIVE

Caveolin-1 (Cav-1), as the main component of caveolae, has complex roles in tumourigenesis in human malignancies. We investigated Cav-1 in primary and metastatic tumor cells of gastric cancer (GC) and its association with clinical outcomes.

METHODS

We retrieved 145 cases of GC who had undergone curative gastrectomy. The expression levels of Cav-1 was evaluated by immunohistochemistry, and its association with clinicopathological parameters and patient survival was analyzed.

RESULTS

High expression of Cav-1 protein of the GC in the stomach and metastatic lymph node was 12.4% (18/145) and 16.5% (15/91). In the multivariate analysis, tumoral Cav-1 protein in metastatic lymph node showed prognostic significance for relapse-free survival (RFS, HR, 3.934; 95% CI, 1.882-8.224; P = 0.001) and cancer-specific survival outcome (CSS, HR, 2.681; 95% CI, 1.613-8.623; P = 0.002). Among the GCs with metastatic lymph node, it remained as a strong indicator of poor prognosis for RFS (HR, 3.136; 95% CI, 1.444-6.810; P = 0.004) and CSS (HR, 2.509; 95% CI, 1.078-5.837; P = 0.032).

CONCLUSION

High expression of tumoral Cav-1 protein in metastatic lymph node is associated with unfavorable prognosis of curative resected GC, indicating the potential of novel prognostic markers.

Effect of cancer-associated fibroblasts on radiosensitivity of cancer cells

Solid tumors are composed of tumor epithelial cells and the stroma, which are seemingly separate but actually related through cell-cell and cell-matrix interactions. These interactions can promote tumor evolution. Cancer-associated fibroblasts (CAFs) are the most abundant non-neoplastic cells in the stroma and also among the most important cell types interacting with cancer cells. Particularly, cancer cells promote the formation and maintenance of CAFs by secreting various cytokines. The activated CAFs then synthesize a series of growth factors to promote tumor cell growth, invasion and metastasis. More importantly, the presence of CAFs also interferes with therapeutic efficacy, bringing severe challenges to radiotherapy. This review summarizes the effect of CAFs on the radiosensitivity of tumor cells and underscores the need for further studies on CAFs in order to improve the efficacy of antitumor therapy.

Chemotherapy oxaliplatin sensitizes prostate cancer to immune checkpoint blockade therapies via stimulating tumor immunogenicity

Even though standard treatment options are available for prostate cancer patients, prostate cancer is still a leading cause of death in many Western countries due to drug resistance and recurrence. Immune checkpoint blockade therapy has been proved to be very effective in some melanoma patients, which might dependent on the preconditioned immune system. Here we explored the effect of chemotherapy (oxaliplatin) in combination with immune checkpoint blockade therapy (anti‑PD‑1 treatment) in prostate cancer cell lines and pre‑clinical animal models. We found that oxaliplatin is effective in castration‑resistant cells and enhanced the response of prostate cancer to anti‑PD‑1 antibody treatment. Oxaliplatin stimulated the immunogenic potential and established a pro‑immune microenvironment in prostate cancer. In conclusion, oxaliplatin sensitized anti‑PD‑1 treatment in prostate cancer and this combination may be an option for castration‑resistant prostate cancer patients.

Caveolin-1: An Oxidative Stress-Related Target for Cancer Prevention

Aberrant oxidative metabolism is one of the hallmarks of cancer. Reactive species overproduction could promote carcinogenesis via inducing genetic mutations and activating oncogenic pathways, and thus, antioxidant therapy was considered as an important strategy for cancer prevention and treatment. Caveolin-1 (Cav-1), a constituent protein of caveolae, has been shown to mediate tumorigenesis and progression through oxidative stress modulation recently. Reactive species could modulate the expression, degradation, posttranslational modifications, and membrane trafficking of Cav-1, while Cav-1-targeted treatments could scavenge the reactive species. More importantly, emerging evidences have indicated that multiple antioxidants could exert antitumor activities in cancer cells and protective activities in normal cells by modulating the Cav-1 pathway. Altogether, these findings indicate that Cav-1 may be a promising oxidative stress-related target for cancer antioxidant prevention. Elucidating the underlying interaction mechanisms between oxidative stress and Cav-1 is helpful for enhancing the preventive effects of antioxidants on cancer, for improving clinical outcomes of antioxidant-related therapeutics in cancer patients, and for developing Cav-1 targeted drugs. Herein, we summarize the available evidence of the roles of Cav-1 and oxidative stress in tumorigenesis and development and shed novel light on designing strategies for cancer prevention or treatment by utilizing the interaction mode between Cav-1 and oxidative stress.

Fibroblast Activation Protein-α-Positive Fibroblasts Promote Gastric Cancer Progression and Resistance to Immune Checkpoint Blockade

Gastric cancer (GC) is one of the main causes of cancer death. The tumor microenvironment has a profound effect on inducing tumor growth, metastasis, and immunosuppression. Fibroblast activation protein-α (FAP) is a protein that is usually expressed in fibroblasts, such as cancer-associated fibroblasts, which are major components of the tumor microenvironment. However, the role of FAP in GC progression and treatment is still unknown. In this study, we explored these problems based on GC patient samples and experimental models. We found that high FAP expression was an independent prognosticator of poor survival in GC patients. FAP+ cancer-associated fibroblasts (CAFs) promoted the survival, proliferation, and migration of GC cell lines in vitro. Moreover, they also induced drug resistance of the GC cell lines and inhibited the antitumor functions of T cells in the GC tumor microenvironment. More importantly, we found that targeting FAP+ CAFs substantially enhanced the antitumor effects of immune checkpoint blockades in GC xenograft models. This evidence highly suggested that FAP is a potential prognosticator of GC patients and a target for synergizing with other treatments, especially immune checkpoint blockades in GC.

Targeting Smoothened Sensitizes Gastric Cancer to Chemotherapy in Experimental Models

BACKGROUND The Hedgehog pathway receptor smoothened (SMO) has critical roles in tumor progression. However, whether SMO is a key factor regulating gastric cancer chemotherapy resistance is unknown. MATERIAL AND METHODS We investigated the potential functions of SMO in inducing gastric cancer paclitaxel resistance in clinical samples, gastric cancer cell lines (424GC and AGS), and subcutaneous syngeneic mouse models. RESULTS We found high SMO expression in paclitaxel-resistant gastric cancer clinical samples. Paclitaxel gastric cancer cells had higher SMO expression than in drug-sensitive cells. Upregulating SMO expression induced paclitaxel resistance in gastric cells lines via enhancing cell proliferation and inhibiting apoptosis. The combination of IPI-926, an inhibitor of SMO, with paclitaxel decreased cell viability of paclitaxel-resistant gastric cancer cells in vitro and controlled tumor growth in animal models. CONCLUSIONS The Hedgehog pathway receptor SMO is an important regulator of gastric cancer paclitaxel resistance and could be a target for sensitizing paclitaxel-resistant tumors.

Prognostic significance of autophagy-related proteins expression in resected human gastric adenocarcinoma

Gastric adenocarcinoma (GC) is one of the most common malignancies in the world and one of the most frequent causes of cancer-related death. Autophagy is a highly regulated catabolic pathway responsible for the degradation of long-lived proteins and damaged intracellular organelles. However, the mechanism and guiding significance of autophagy in the development and progression of GC have remained to be elucidated. This study aimed to explore the clinicopathological significances and prognostic values of autophagy-related proteins AMBRA1 and Beclin-1 in GC. Quantum dots based immunofluorescence histochemistry (QDs-IHC) was performed to observe the expression of AMBRA1 and Beclin-1 proteins in the tissue microarrays including 163 specimens of GC and 20 noncancerous gastric tissues. Simultaneously, AMBRA1 and Beclin-1 proteins were detected by Western blotting in the 10 fresh GC and corresponding normal gastric tissues. The results showed that the expression levels of both AMBRA1 and Beclin-1 proteins were higher in GC tissues than in noncancerous gastric tissues by QDs-IHC and Western blotting (P<0.05). High AMBRA1 expression was detected in 90 of 163 (55.2%) GCs and high Beclin-1 expression was detected in 83 of 163 (50.9%) GCs. High AMBRA1 expression was closely related to depth of invasion, and lymph nodes metastasis (P<0.05). High expression of Beclin-1 protein was correlated with tumor grade (P<0.05). Positive correlation was observed between AMBRA1 and Beclin-1. Survival analysis indicated the high expression of AMBRA1 and Beclin- 1 was an independent factor in predicting poor overall survival (OS) of GC patients. These findings suggest the high expression of AMBRA1 and Beclin-1 proteins is significantly correlated with GC progression. High AMBRA1 and Beclin-1 expression heralds worse outcome of GC patients, suggesting a novel candidate prognostic marker and a therapeutic target for GC.

Prognostic and Therapeutic Values of Tumor Necrosis Factor-Alpha in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) causes many deaths worldwide every year, especially in Asia. It is characterized by high malignancy, recurrence, and short survival time. Inflammation is closely related to the initiation and development of HCC. Tumor necrosis factor-α (TNF-α), an essential inflammatory mediator, has been studied as a potential therapy target in many cancers. However, its potential role in HCC diagnosis and therapy is still unclear.

Material/Methods

In our study, we detected the TNF-α expression in both human HCC tumor tissue and HCC cell lines HepG2 and HuH7. Then, we detected the effect of anti-TNF-α treatment and it synergistic function with 5-FU in an HCC xenograft mouse model and in HCC cell lines.

Results

Survival analysis and Cox regression analysis based on 97 HCC patients indicated that a high level of TNF-α is an independent predictor of poor survival in HCC patients. Anti-TNF-α treatment by infliximab synergizes with Fluorouracil (5-FU) by promoting apoptosis of HCC tumor cells through complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) effects.

Conclusions

Based on these data, we conclude that anti-TNF-α treatment could be a good way to increase the effect of classic chemotherapy of HCC patients, especially for the patients who have modest response to classic chemotherapy, such as 5-FU. TNF-α could also be used as a biomarker to help in early diagnosis of HCC.

Infliximab enhances the therapeutic effects of 5-fluorouracil resulting in tumor regression in colon cancer

Colon cancer (CC) is among the most common malignant diseases with a dismal survival. Tumor necrosis factor-alpha (TNF-α) has been identified as a therapeutic target in various cancers, and anti-TNF-α treatment has shown promising effects in different cancer models. However, if TNF-α can be targeted in CC, the therapeutic values of anti-TNF-α treatment in CC remain unknown. Our study indicated that TNF-α is highly expressed in CC cell lines and patient tumor samples. High expression of TNF-α is an independent adverse prognosticator of CC. Targeting the TNF-α by its antibody infliximab induced antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity and enhanced apoptosis leading to cell death. The combination of infliximab with 5-fluorouracil showed better responses in vitro and in vivo than 5-fluorouracil alone. In conclusion, this study identified TNF-α as a target of CC and anti-TNF-α treatment synergized with chemotherapy leading to a better outcome in preclinical models.

A Mimic of the Tumor Microenvironment: A Simple Method for Generating Enriched Cell Populations and Investigating Intercellular Communication

Understanding the early heterotypic interactions between cancer cells and the surrounding non-cancerous stroma is important in elucidating the events leading to stromal activation and establishment of the tumor microenvironment (TME). Several in vitro and in vivo models of the TME have been developed; however, in general these models do not readily permit isolation of individual cell populations, under non-perturbing conditions, for further study. To circumvent this difficulty, we have employed an in vitro TME model using a cell growth substrate consisting of a permeable microporous membrane insert that permits simple generation of highly enriched cell populations grown intimately, yet separately, on either side of the insert's membrane for extended co-culture times. Through use of this model, we are capable of generating greatly enriched cancer-associated fibroblast (CAF) populations from normal diploid human fibroblasts following co-culture (120 hr) with highly metastatic human breast carcinoma cells, without the use of fluorescent tagging and/or cell sorting. Additionally, by modulating the pore-size of the insert, we can control for the mode of intercellular communication (e.g., gap-junction communication, secreted factors) between the two heterotypic cell populations, which permits investigation of the mechanisms underlying the development of the TME, including the role of gap-junction permeability. This model serves as a valuable tool in enhancing our understanding of the initial events leading to cancer-stroma initiation, the early evolution of the TME, and the modulating effect of the stroma on the responses of cancer cells to therapeutic agents.

Role of cancer-associated fibroblasts in invasion and metastasis of gastric cancer

Cancer-associated fibroblasts (CAFs) are important components of various types of tumors, including gastric cancer (GC). During tumorigenesis and progression, CAFs play critical roles in tumor invasion and metastasis via a series of functions including extracellular matrix deposition, angiogenesis, metabolism reprogramming and chemoresistance. However, the mechanism of the interaction between gastric cancer cells and CAFs remains largely unknown. MicroRNAs (miRNAs) are a class of non-coding small RNA molecules, and their expression in CAFs not only regulates the expression of a number of target genes but also plays an essential role in the communication between tumor cells and CAFs. In this review, we provide an overview of recent studies on CAF miRNAs in GC and the relevant signaling pathways in gastrointestinal tumors. Focusing the attention on these signaling pathways may help us better understand their role in tumor invasion and metastasis and identify new molecular targets for therapeutic strategies.

The stromal cell-surface protease fibroblast activation protein-α localizes to lipid rafts and is recruited to invadopodia

Fibroblast activation protein alpha (FAPα) is a cell surface protease expressed by cancer-associated fibroblasts in the microenvironment of most solid tumors. As there is increasing evidence for proteases having non-catalytic functions, we determined the FAPα interactome in cancer-associated fibroblasts using the quantitative immunoprecipitation combined with knockdown (QUICK) method. Complex formation with adenosin deaminase, erlin-2, stomatin, prohibitin, Thy-1 membrane glycoprotein, and caveolin-1 was further validated by immunoblotting. Co-immunoprecipitation (co-IP) of the known stoichiometric FAPα binding partner dipeptidyl-peptidase IV (DPPIV) corroborated the proteomic strategy. Reverse co-IPs validated the FAPα interaction with caveolin-1, erlin-2, and stomatin while co-IP upon RNA-interference mediated knock-down of DPPIV excluded adenosin deaminase as a direct FAPα interaction partner. Many newly identified FAPα interaction partners localize to lipid rafts, including caveolin-1, a widely-used marker for lipid raft localization. We hypothesized that this indicates a recruitment of FAPα to lipid raft structures. In density gradient centrifugation, FAPα co-fractionates with caveolin-1. Immunofluorescence optical sectioning microscopy of FAPα and lipid raft markers further corroborates recruitment of FAPα to lipid rafts and invadopodia. FAPα is therefore an integral component of stromal lipid rafts in solid tumors. In essence, we provide one of the first interactome analyses of a cell surface protease and translate these results into novel biological aspects of a marker protein for cancer-associated fibroblasts.

Registered report: Biomechanical remodeling of the microenvironment by stromal caveolin-1 favors tumor invasion and metastasis

The Reproducibility Project: Cancer Biology seeks to address growing concerns about reproducibility in scientific research by conducting replicating selected results from a number of high-profile papers in the field of cancer biology. The papers, which were published between 2010 and 2012 were selected on the basis of citations and Altimetric scores (Errington et al., 2014). This Registered report describes the proposed replication plan of key experiments from ‘Biomechanical remodeling of the microenvironment by stromal caveolin-1 favors tumor invasion and metastasis’ by Goetz and colleagues, published in Cell in 2011 (Goetz et al., 2011). The key experiments being replicated are those reported in Figures 7C (a-d), Supplemental Figure S2A, and Supplemental Figure S7C (a-c) (Goetz et al., 2011). In these experiments, which are a subset of all the experiments reported in the original publication, Goetz and colleagues show in a subcutaneous xenograft model that stromal caveolin-1 remodels the intratumoral microenvironment, which is correlated with increased metastasis formation. The Reproducibility Project: Cancer Biology is a collaboration between the Center for Open Science and Science Exchange and the results of the replications will be published in eLife.

DOI:http://dx.doi.org/10.7554/eLife.04796.001

High monocarboxylate transporter 4 protein expression in stromal cells predicts adverse survival in gastric cancer

BACKGROUND

Increasing evidence suggests that stromal monocarboxylate transporter 4 (MCT4) and carbonic anhydrase IX (CA IX) may play key roles in tumor development. However, their clinical value remains largely unexplored in gastric cancer (GC). The present study aimed to determine clinicopathological significance and prognostic values of stromal MCT4 and CA IX in GC.

MATERIALS AND METHODS

Specimens from 143 GC patients were immunohistochemically stained using polyclonal anti-MCT4 and anti-CA IX antibodies. Expression was correlated with patient clinicopathologic characteristics and survival data.

RESULTS

High stromal MCT4 expression was detected in 72 of 143 (50.3%) GCs and high CA IX in 74 (51.7%). Both high stromal MCT4 and CA IX were correlated with advanced TNM stage (p=0.000; p=0.000). High CA IX expression was positively related to depth of invasion (p=0.022) and positive lymph nodes (p=0.002) as well. Survival analysis indicated high expression of stromal MCT4 to be an independent factor in predicting poor overall survival (OS) (HR and 95%CI=1.962, 1.032-3.729, p=0.040) and disease free survival (DFS) (HR and 95%CI=2.081, 1.158-3.741, p=0.014) of GC patients. However, high CA IX expression exhibited no significant predictive value.

CONCLUSIONS

These findings suggest that high expression of stromal MCT4 and CA IX proteins is significantly correlated with GC progression. High stromal MCT4 heralds worse outcome of GC patient, suggesting a novel candidate prognostic marker and therapeutic target.

Methyl-methanesulfonate sensitivity 19 expression is associated with metastasis and chemoradiotherapy response in esophageal cancer

AIM: To investigate the clinical significance of methyl-methanesulfonate sensitivity 19 (MMS19) expression in esophageal squamous cell carcinoma (ESCC).

METHODS: Between June 2008 and May 2013, specimens from 103 patients who underwent endoscopic biopsy for the diagnosis of ESCC at the endoscopy center of Sun Yat-Sen University Cancer Center were collected; 52 matched-normal esophageal squamous epithelium samples were biopsied as controls. MMS19 protein expression was measured by immunohistochemistry. Of the 103 cases of ESCC, 49 received radical surgery following neoadjuvant chemoradiotherapy consisting of concurrent radiation in a total dose of 40 Gy and two cycles of chemotherapy with vinorelbine and cisplatin. Relationships between MMS19 expression, clinicopathologic characteristics and chemoradiotherapy response were analyzed.

RESULTS: The MMS19 protein could be detected in both the cytoplasm and nucleus of most specimens. High cytoplasmic expression of MMS19 was detected in 63.1% of ESCC samples, whereas high nuclear expression of MMS19 was found in 35.0%. High cytoplasmic MMS19 expression was associated with regional lymph node metastases (OR = 11.3, 95%CI: 2.3-54.7; P < 0.001) and distant metastases (OR = 13.1, 95%CI: 1.7-103.0; P = 0.002). Furthermore, high cytoplasmic MMS19 expression was associated with a response of ESCC to chemoradiotherapy (OR = 11.5, 95%CI: 3.0-44.5; P < 0.001), with a high cytoplasmic MMS19 expression rates in 79.3% and 25.0% of patients from the good chemoradiotherapy response group and poor response group, respectively. Nuclear MMS19 expression did not show any significant association with clinicopathologic characteristics or chemoradiotherapy response in ESCC.

CONCLUSION: The results of our preliminary study suggest that MMS19 may be a potential new predictor of metastasis and chemoradiotherapy response in ESCC.

Caveolae and signalling in cancer

It has been over 20 years since the discovery that caveolar lipid rafts function as signalling organelles. Lipid rafts create plasma membrane heterogeneity, and caveolae are the most extensively studied subset of lipid rafts. A newly emerging paradigm is that changes in caveolae also generate tumour metabolic heterogeneity. Altered caveolae create a catabolic tumour microenvironment, which supports oxidative mitochondrial metabolism in cancer cells and which contributes to dismal survival rates for cancer patients. In this Review, we discuss the role of caveolae in tumour progression, with a special emphasis on their metabolic and cell signalling effects, and their capacity to transform the tumour microenvironment.

Caveolin-1 is a modulator of fibroblast activation and a potential biomarker for gastric cancer

Stromal fibroblasts play an important role in chronic cancer-related inflammation and the development as well as progression of malignant diseases. However, the difference and relationship between inflammation-associated fibroblasts (IAFs) and cancer-associated fibroblasts (CAFs) are poorly understood. In this study, gastric cancer-associated fibroblasts (GCAFs) and their corresponding inflammation-associated fibroblasts (GIAFs) were isolated from gastric cancer (GC) with chronic gastritis and cultured in vitro. These activated fibroblasts exhibited distinct secretion and tumor-promoting behaviors in vitro. Using proteomics and bioinformatics techniques, caveolin-1 (Cav-1) was identified as a major network-centric protein of a sub-network consisting of 121 differentially expressed proteins between GIAFs and GCAFs. Furthermore, immunohistochemistry in a GC cohort showed significant difference in Cav-1 expression score between GIAFs and GCAFs and among patients with different grades of chronic gastritis. Moreover, silencing of Cav-1 in GIAFs and GCAFs using small interfering RNA increased the production of pro-inflammatory and tumor-enhancing cytokines and chemokines in conditioned mediums that elevated cell proliferation and migration when added to GC cell lines AGS and MKN45 in vitro. In addition, Cav-1 status in GIAFs and GCAFs independently predicted the prognosis of GC. Our findings indicate that Cav-1 loss contributes to the distinct activation statuses of fibroblasts in GC microenvironment and gastritis mucosa, and Cav-1 expression in both GCAFs and GIAFs may serve as a potential biomarker for GC progression.

Loss of stromal caveolin-1 expression in colorectal cancer predicts poor survival

AIM: To investigate the clinicopathological significance and prognostic value of caveolin-1 (CAV-1) in both tumor and stromal cells in colorectal cancer (CRC).

METHODS: A total of 178 patients with CRC were included in this study. The correlation between CAV-1 expression and clinicopathologic features and survival was studied.

RESULTS: CAV-1 expression was detected in tumor and stromal cells. The expression of stromal CAV-1 was closely associated with histological type (P = 0.022), pathologic tumor-node-metastasis stage (P = 0.047), pathologic N stage (P = 0.035) and recurrence (P = 0.000). However, tumor cell CAV-1 did not show any correlation with clinical parameters. Additionally, the loss of stromal CAV-1 expression was associated with shorter disease-free survival (P = 0.000) and overall survival (P = 0.000). Multivariate analysis revealed that the loss of stromal CAV-1 expression was an independent prognostic factor for both overall survival (P = 0.014) and disease-free survival (P = 0.006).

CONCLUSION: The loss of stromal CAV-1 expression in CRC was associated with poor prognosis and could be a prognostic factor for CRC patients.

Quantum dots immunofluorescence histochemical detection of EGFR gene mutations in the non-small cell lung cancers using mutation-specific antibodies

BACKGROUND

Epidermal growth factor receptor (EGFR) mutation status plays an important role in therapeutic decision making for non-small cell lung cancer (NSCLC) patients. Since EGFR mutation-specific antibodies (E746-A750del and L858R) have been developed, EGFR mutation detection by immunohistochemistry (IHC) is a suitable screening test. On this basis, we want to establish a new screening test, quantum dots immunofluorescence histochemistry (QDs-IHC), to assess EGFR gene mutation in NSCLC tissues, and we compared it to traditional IHC and amplification refractory mutation system (ARMS).

MATERIALS AND METHODS

EGFR gene mutations were detected by QDs-IHC, IHC, and ADx-ARMS in 65 cases of NSCLC composed of 55 formalin-fixed, paraffin-embedded specimens and ten pleural effusion cell blocks, including 13 squamous cell carcinomas, two adenosquamous carcinomas, and 50 adenocarcinomas.

RESULTS

Positive rates of EGFR gene mutations detected by QDs-IHC, IHC, and ADx-ARMS were 40.0%, 36.9%, and 46.2%, respectively, in 65 cases of NSCLC patients. The sensitivity of QDs-IHC when detecting EGFR mutations, as compared to ADx-ARMS, was 86.7% (26/30); the specificity for both antibodies was 100.0% (26/26). IHC sensitivity was 80.0% (24/30) and the specificity was 92.31% (24/26). When detecting EGFR mutations, QDs-IHC and ADx-ARMS had perfect consistency (κ  =0.882; P<0.01). Excellent agreement was observed between IHC and ADx-ARMS when detecting EGFR mutations (κ  =0.826; P<0.01).

CONCLUSION

QDs-IHC is a simple and standardized method to detect EGFR mutations with its high sensitivity and specificity, as compared with real-time polymerase chain reaction. In addition, the development of specific antibodies against EGFR mutation proteins might be useful for the diagnosis and treatment of lung cancer.