Down-regulation of stromal caveolin-1 expression in esophageal squamous cell carcinoma: a potent predictor of lymph node metastases, early tumor recurrence, and poor prognosis

Single-cell analysis identified POSTN+ cells associated with the aggressive phenotype and risk of esophageal squamous cell carcinoma

Tumors are intricate and heterogeneous systems characterized by mosaic cancer cell populations with diverse expression profiles. Leveraging single-cell technologies, we employed the Scissor algorithm to delineate an epithelial subpopulation associated with the aggressive phenotype in esophageal squamous cell carcinoma (ESCC). This identified subpopulation exhibited elevated expression of genes involved in critical pathways, such as epithelial-mesenchymal transition and PI3K-Akt. Key signature genes within this subpopulation, namely CAV1, COL3A1, COL6A1, POSTN, and TAGLN, demonstrated significant upregulation concomitant with both tumorigenesis and tumor progression across independent single-cell datasets. Furthermore, we selected 1,450 expression quantitative trait loci of the top 62 signature genes of this cell subpopulation to investigate their potential in predicting ESCC risk. The results showed that the POSTN loci were predominantly associated with ESCC susceptibility. Through functional annotation and replication analyses, we identified that the rs1028728 in the POSTN promoter was significantly associated with increased ESCC risk in 7,049 ESCC cases and 8,063 controls (odds ratio = 1.29, 95% confidence interval: 1.18-1.42, p = 4.03 × 10-8). Subsequent biochemical experiments showed that the rs1028728[T] allele enhanced POSTN expression by affecting the binding of PRRX1 in the POSTN promoter. In summary, our meticulous single-cell analysis delineates an invasive epithelial subpopulation in ESCC, with POSTN emerging as an important marker for the aggressive phenotype. These findings offer more insights into potential strategies for the prevention and intervention of ESCC, enriching our understanding of this complex cancer landscape.

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.

CAV1 Impacts the Tumor Immune Microenvironment and Has Potential Value of Predicting Response to Immunotherapy in Esophageal Cancer

Caveolin-1 (CAV1) is one of the members of the caveolae, and the role of CAV1 in esophageal cancer (ESCA) is not completely clear. In this study, we found that expression of CAV1 was downregulated in ESCA in The Cancer Genome Atlas and the Genotype-Tissue Expression (GTEx) database and we also use immunohistochemistry of tissue microarray for verification. Then, we used bioinformatics methods to investigate the prognostic value of CAV1, influence on immune cell infiltration in tumor microenvironment (TME) and responding to immunotherapy in ESCA. Our result indicated that CAV1 designs an inflamed TME in ESCA based on the evidence that CAV1 positively correlated with immunomodulators, immune score, stomal score, cancer immunity cycles, tumor-infiltrating immune cells, T cell inflamed score, and immune checkpoints. Immunophenoscore, Tumor Immune Dysfunction and Exclusion algorithms, and the mutation analysis show that the downregulated CAV1 expression indicated higher tumor mutation burden and higher rate of response to immune checkpoint inhibitors (ICIs) in the low-expression group. In a word, our study demonstrated the impact of CAV1 to the TME in ESCA and it may be a new target for ESCA immunotherapy. In addition, the expression of CAV1 can predict the clinical response to ICIs, which may provide clinical treatment guidance.

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.

Caveolin-1 expression predicts favourable outcome and correlates with PDGFRA mutations in gastrointestinal stromal tumours (GISTs)

AIMS

Novel prognostic markers are warranted for gastrointestinal stromal tumours. Caveolin-1 is a multifunctional protein that proved to be associated with outcome in multiple tumour types. Aim of this study was to investigate Caveolin-1 expression and prognostic efficacy in a series of gastrointestinal stromal tumours.

METHODS

Caveolin-1 expression was assessed by immunohistochemistry in a retrospective series of 66 gastrointestinal stromal tumours representative of the different molecular subtypes. Correlations with clinical, histopathological and molecular features were investigated. Statistical analyses were performed as appropriate.

RESULTS

Thirty-five cases out of 66 (53.0%) expressed Caveolin-1. Presence of Caveolin-1 expression correlated with favourable histopathologic and clinical traits, including a lower mitotic count (p=0.003) and lower relapse rate (p=0.005). Caveolin-1 expression also resulted associated with the presence of PDGFRA mutations (p=0.010). Outcome analyses showed a favourable prognostic significance of Caveolin-1 expression in terms of relapse-free survival (HR=0.14; 95% CI=0.03 to 0.63) and overall survival (HR=0.29; 95% CI=0.11 to 0.74), even after adjusting for the mutational subgroup (relapse-free survival: HR=0.14, 95% CI=0.04 to 0.44; overall survival: HR=0.29, 95% CI=0.11 to 0.51) and imatinib treatment (relapse-free survival: HR=0.14, 95% CI=0.02 to 0.81; overall survival: HR=0.29, 95% CI=0.17 to 0.48).

CONCLUSION

Caveolin-1 represents a novel prognostic marker in gastrointestinal stromal tumours. Further studies are warranted to validate these results and to explore the mechanisms linking Caveolin-1 expression with the PDGFRA oncogenic pathway.

Monoclonal Caveolin 1 Expression in the Differential Diagnosis of Malignant Pleural Mesothelioma and Pulmonary Adenocarcinoma: Is it Useful?

In this study we aim to demonstrate the value of monoclonal Caveolin 1 expression in distinguishing between malignant pleural mesothelioma and pulmonary adenocarcinoma. Total of 129 cases, consisting of 68 cases of malignant pleural mesothelioma (51 epitheloid, 12 biphasic, and 5 sarcomatoid type) and 61 cases of pulmonary adenocarcinoma were examined and stained with monoclonal Caveolin-1. Caveolin 1 expression with a membranous and /or cytoplasmic pattern was detected only in 32.35% (n:22/68) of malignant pleural mesothelioma and 6.5% (n:4/61) of pulmonary adenocarcinoma cases. This finding suggests that the choice of poly/monoclonal antibody for Caveolin 1 in the differential diagnosis of malignant pleural mesothelioma and pulmonary adenocarcinoma is important.

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.

Loss of Caveolin-1 in Metastasis-Associated Macrophages Drives Lung Metastatic Growth through Increased Angiogenesis

Although it is well established that tumor-associated macrophages take part in each step of cancer progression, less is known about the distinct role of the so-called metastasis-associated macrophages (MAMs) at the metastatic site. Previous studies reported that Caveolin-1 (Cav1) has both tumor-promoting and tumor-suppressive functions. However, the role of Cav1 in bone-marrow-derived cells is unknown. Here, we describe Cav1 as an anti-metastatic regulator in mouse models of lung and breast cancer pulmonary metastasis. Among all the recruited inflammatory cell populations, we show that MAMs uniquely express abundant levels of Cav1. Using clodronate depletion of macrophages, we demonstrate that macrophage Cav1 signaling is critical for metastasis and not for primary tumor growth. In particular, Cav1 inhibition does not affect MAM recruitment to the metastatic site but, in turn, favors angiogenesis. We describe a mechanism by which Cav1 in MAMs specifically restrains vascular endothelial growth factor A/vascular endothelial growth factor receptor 1 (VEGF-A/VEGFR1) signaling and its downstream effectors, matrix metallopeptidase 9 (MMP9) and colony-stimulating factor 1 (CSF1).

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Macrophage Cav1 signaling is critical for restraining lung metastatic growth

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Cav1 deletion in macrophages favors angiogenesis at the lung metastatic site

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Cav1 suppresses VEGF-A/VEGFR1 activity and its downstream effectors, MMP9 and CSF1

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.

Cancer associated fibroblasts tailored tumor microenvironment of therapy resistance in gastrointestinal cancers

Gastrointestinal cancers (GI), are a group of highly aggressive malignancies with heavy cancer-related mortalities. Even if continued development of therapy methods, therapy resistance has been a great obstruction for cancer treatment and thereby inevitably leads to depressed final mortality. Peritumoral cancer associated fibroblasts (CAFs), a versatile population assisting cancer cells to build a facilitated tumor microenvironment (TME), has been demonstrated exerting a promotion influence on cancer proliferation, migration, invasion, metastasis, and also therapy resistance. In this review, we provide an update progress in describing how CAFs mediate therapy resistance in GI by various means, meanwhile highlight the crosstalk between CAFs and cancer cells and present some vital signaling pathways activated by CAFs in this resistant process. Furthermore, we discuss the current advances in adopting novel drugs against CAFs and how the knowledge contributing to improved therapy efficacy in clinical practice. In sum, CAFs create a therapy-resistant TME in several aspects of GI progression, although some key problems about distinguishing CAFs subpopulations and controversial issues on pleiotropic CAFs in medication need to be solved for subsequent clinical application. Predictably, targeting therapy-resistant CAFs is a promising adjunctive treatment to benefit GI patients.

A comprehensive expression analysis of the MIA gene family in malignancies: MIA gene family members are novel, useful markers of esophageal, lung, and cervical squamous cell carcinoma

Melanoma inhibitory activity (MIA) gene family members include MIA, MIA2, and Transport and Golgi organization protein 1 (TANGO). Although MIA gene family members have several tumor-related functions, their detailed roles in malignancies remain poorly elucidated. In this study, 477 tumor specimens were subjected to immunohistochemical screening to evaluate MIA gene family expression. For a validation analysis, we also examined the association between MIA gene family expression and clinicopathological factors in 66 cases of esophageal cancer, 145 cases of lung cancer, and 126 cases of cervical cancer. The frequency of MIA gene family expression was higher among squamous cell carcinomas than among other tumor types subjected to screening. In the validation analysis, MIA gene family staining was observed frequently in esophageal and lung cancers associated with nodal and/or distant metastasis. In cervical cancers, MIA and TANGO immunostaining also correlated with tumor progression and metastasis. Furthermore, MIA2 expression levels in invasive cervical cancer were upregulated relative to those in cervical intraepithelial neoplasia 3. A disease-free survival analysis revealed that MIA-, MIA2, or TANGO-positive patients had a significantly shorter disease-free survival than did those patients who were negative. Our results suggest that MIA, MIA2, and TANGO may be useful diagnostic and therapeutic molecular targets in human malignancies.

Rho/ROCK Pathway Regulates Migration and Invasion of Esophageal Squamous Cell Carcinoma by Regulating Caveolin-1

BACKGROUND Esophageal squamous cell carcinoma (ESCC) is a common cancer with poor prognosis. Caveolin-1 (Cav1) and Rho/ROCK pathway play important roles in tumor metastasis, separately. However, less research was focused on the relationship between Cav1 and Rho/ROCK in ECSS metastasis. Therefore, we investigated the relationship between Cav1 and Rho/ROCK pathway in ESCC metastasis. MATERIAL AND METHODS Cav1 and phosphorylated Cav1 (PY14Cav1) were examined in ESCC and in adjacent and non-tumorous tissues from ESCC patients by immunohistochemistry (IHC). Small interfering RNA (siRNA) targeting Cav1 or Rho/ROCK inhibitor was used to treat EC109, Eca109, TE1, and TE13 cells. Western blotting (WB) was used to detect Cav1 and PY14Cav1 expression. The wound healing scratch test and transwell assays were used to assess migration and invasion. RESULTS Cav1 and PY14Cav1 were gradually expressed at higher levels in ECSS than in adjacent and non-tumor tissues as ESCC stage and lymphatic metastasis increased, and this difference was significant (P<0.05). Cav1 was expressed at higher levels in TE1 and TE13 than in EC109 and Eca109, while PY14Cav1 was enhanced in TE1 and TE13 cells but not in EC109 and Eca109, and the difference was significant (P<0.05). TE1 and TE13 had significantly (P<0.05) stronger motility, migratory, and invasion abilities than EC109 and Eca109 cells. Silencing Cav1 decreased PY14Cav1 expression in TE1 and TE13 cells, as well as suppressing the migration and invasion of all ECSS cells, and these differences were significant (P<0.05). Suppressing the Rho/ROCK pathway obviously inhibited Cav1 and PY14Cav1 expressions, as well as significantly (P<0.05) decreasing migration and invasion of ESCC cells. CONCLUSIONS Cav1 and PY14Cav1 were positively correlated with ESCC lymphatic metastasis and cancer stages. Rho/ROCK pathway activation promoted ESCC metastasis by regulating Cav1.

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.

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.

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.

Caveolin-1 expression in oral lichen planus, dysplastic lesions and squamous cell carcinoma

Caveolin-1(Cav-1), the main part of caveolae structure, is supposed to play a role in pathogenesis of many human tumors. Since oral lichen planus (OLP) is considered as a potential premalignant disease, this study evaluated Cav-1 expression in OLP in comparison with benign hyperkeratosis, dysplastic epithelium and oral squamous cell carcinoma (OSCC), to investigate its possible role in pathogenesis and malignant transformation of OLP. In this cross-sectional retrospective study, immunohistochemical expression of Cav-1 in the epithelial component and stroma was evaluated in 81 samples, including 12 cases of hyperkeratosis, 24 OLP, 22 epithelial dysplasia, and 23 OSCC samples. Correlations between Cav-1 expression and clinicopathological variables were evaluated statistically. Positive Cav-1 staining was found in 58% of OLP, 91% of hyperkeratosis, 100% of epithelial dysplasia, and 95% of OSCC samples. OSCC showed the highest Cav-1 expression and OLP had the lowest (P=0.001). The intensity of staining was significantly increased in stepwise manner from OLP to OSCC (P=0.001). Expression of Cav-1 was related to the grade of samples in OSCC and dysplastic samples (P=0.04). Based on the findings, it was concluded that Cav-1 may play a role in the pathogenesis of OLP and carcinogenesis of SCC, but its role in malignant transformation of OLP is not confirmed. Further studies are needed to evaluate its potential therapeutic function in OLP and SCC.

The different functions and clinical significances of caveolin-1 in human adenocarcinoma and squamous cell carcinoma

Caveolin-1 (Cav-1), a major structural protein of caveolae, is an integral membrane protein which plays an important role in the progression of carcinoma. However, whether Cav-1 acts as a tumor promoter or a tumor suppressor still remains controversial. For example, the tumor-promoting function of Cav-1 has been found in renal cancer, prostate cancer, tongue squamous cell carcinoma (SCC), lung SCC and bladder SCC. In contrast, Cav-1 also plays an inhibitory role in esophagus adenocarcinoma, lung adenocarcinoma and cutaneous SCC. The role of Cav-1 is still controversial in thyroid cancer, hepatocellular carcinoma, gastric adenocarcinoma, colon adenocarcinoma, breast cancer, pancreas cancer, oral SCC, laryngeal SCC, head and neck SCC, esophageal SCC and cervical SCC. Besides, it has been reported that the loss of stromal Cav-1 might predict poor prognosis in breast cancer, gastric cancer, pancreas cancer, prostate cancer, oral SCC and esophageal SCC. However, the accumulation of stromal Cav-1 has been found to be promoted by the progression of tongue SCC. Taken together, Cav-1 seems playing a different role in different cancer subtypes even of the same organ, as well as acting differently in the same cancer subtype of different organs. Thus, we hereby explore the functions of Cav-1 in human adenocarcinoma and SCC from the perspective of clinical significances and pathogenesis. We envision that novel targets may come with the further investigation of Cav-1 in carcinogenesis.

Proteomic analysis indicates the importance of TPM3 in esophageal squamous cell carcinoma invasion and metastasis

Numerous esophageal squamous cell carcinoma (ESCC) patients exhibit tumor recurrence following radical resection. Invasion and metastasis are key factors in poor prognosis following esophagectomy. In the present study, two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were used to define patterns of protein expression in ESCC tissues at different pathological stages. The expression levels of identified proteins were determined by immunohistochemistry and western blotting. A total of fifteen protein spots with >2-fold differences were observed when comparing results of 2-DE for stage III and stage I ESCC tissue sample. A total of 12 proteins were identified by mass spectrometry analysis and database searches. The results of immunohistochemistry and western blotting demonstrated expression levels of tropomyosin 3 (TPM3) were higher in stage III ESCC tissue compared with stage I (P<0.05). The findings of the present study identified twelve proteins, which are closely associated with ESCC invasion and metastasis, apoptosis and cell signal transduction. Furthermore, the overexpression of TPM3 may be important in ESCC invasion and metastasis.

β-Carotene synergistically enhances the anti-tumor effect of 5-fluorouracil on esophageal squamous cell carcinoma in vivo and in vitro

Recently, we reported that β-carotene exhibited anticancer activity against human esophageal squamous cell carcinoma cells in vitro. In the present study, we examined a novel therapeutic strategy by combining β-carotene with 5-fluorouracil (5-FU) in human esophageal cancer in vitro and in vivo, and elucidated the underlying mechanisms. We found that the combination of 5-FU and β-carotene displayed greater growth inhibitory effects than did either compound alone in esophageal squamous cell carcinoma (ESCC) cells. In addition, the combination of 5-FU and β-carotene displayed greater tumor growth inhibition in an Eca109 xenograft mouse model than did a single agent with low systemic toxicity. β-Carotene enhanced 5-FU-induced apoptosis. TUNEL staining revealed that the rate of TUNEL-positive cells was markedly increased in tumor tissues after treatment with 5-FU and β-carotene. Western blotting and immunohistochemistry revealed the down-regulation of Bcl-2 and PCNA and the up-regulation of Bax and caspase-3 in tumor tissues. Further studies demonstrated that the combined administration of 5-FU and β-carotene significantly down-regulated the protein levels of Cav-1, p-AKT, p-NF-κB, p-mTOR and p-p70S6K in Eca109 cells more effectively than did 5-FU alone. These data suggested that the combined therapy of 5-FU and β-carotene exerted synergistic antitumor effects in vivo and in vitro and could constitute a novel therapeutic treatment for ESCC.

Clinical potential of miR-3651 as a novel prognostic biomarker for esophageal squamous cell cancer

Accumulating evidence indicates that dysregulated microRNA-3651(miR-3651) is involved in tumorigenesis and cancer progression. In this study, we investigated the expression of miR-3651 in esophageal squamous cell cancer(ESCC) and its relationship with tumor progression and clinical prognosis. The expression level of miR-3651 was examined by quantitative Real-time PCR (qRT-PCR) in fresh ESCC tissues and FFPE tissues. The correlation between miR-3651 expression and clinical features and prognosis were statistically analyzed. The results showed that the miR-3651 expression was significantly down-regulated in tumor tissues compared with the paracancerous tissues. Moreover, miR-3651 expression was negatively correlated with T stage of ESCC (P = 0.022) and tumor length (P = 0.015). Kaplan-Meier analysis demonstrated that low miR-3651 expression level was associated with poorer overall survival (OS) (P = 0.004) and disease-free survival (DFS) (P = 0.001). Multivariate analysis identified miR-3651 expression as independent prognostic factor for OS and DFS (P = 0.001 and P = 0.001, resp.). Further stratified analysis revealed the significant association between low miR-3651 expression and worse survival in early patients, but not in the advanced patients. Taken together, miR-3651 was down-regulated in cancerous tissues of ESCC. It may play an important role in cancer progression and could be used as an independent prognostic biomarker for ESCC patients.

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.

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.

Functional polymorphisms of caveolin-1 variants as potential biomarkers of esophageal squamous cell carcinoma

OBJECTIVE

To investigate the association of caveolin-1 (CAV1) genetic variants (C239A (rs1997623), G14713A (rs3807987), G21985A (rs12672038), T29107A (rs7804372)) with esophageal squamous cell carcinoma (ESCC) susceptibility.

METHODS

A total of 427 patients with ESCC and 427 healthy controls were genotyped using the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

There were significant differences between patients and controls in distributions of their genotypes and allelic frequencies in G14713A and T29107A polymorphisms. Furthermore, haplotype analysis revealed that haplotypes CAAT and CAGT were associated with high risk for ESCC, while haplotype CGGA was protective against ESCC. Stratified analysis showed the associations between the SNPs (G14713A and T29107A) and ESCC risk were noteworthy among female patients and patients who never smoke or drank alcohol.

CONCLUSIONS

Genetic polymorphisms of CAV1 G14713A and T29107A might affect an individual's susceptibility in developing ESCC, making them efficient potential genetic biomarkers for early detection of ESCC.