Host deficiency in caveolin-2 inhibits lung carcinoma tumor growth by impairing tumor angiogenesis

Identification and validation of eight lysosomes-related genes signatures and correlation with immune cell infiltration in lung adenocarcinoma

Lung cancer is the leading cause of cancer-related death. Lysosomes are key degradative compartments that maintain protein homeostasis. In current study, we aimed to construct a lysosomes-related genes signature to predict the overall survival (OS) of patients with Lung Adenocarcinoma (LUAD). Differentially expressed lysosomes-related genes (DELYs) were analyzed using The Cancer Genome Atlas (TCGA-LUAD cohort) database. The prognostic risk signature was identified by Least Absolute Shrinkage and Selection Operator (LASSO)-penalized Cox proportional hazards regression and multivariate Cox analysis. The predictive performance of the signature was assessed by Kaplan-Meier curves and Time-dependent receiver operating characteristic (ROC) curves. Gene set variant analysis (GSVA) was performed to explore the potential molecular biological function and signaling pathways. ESTIMATE and single sample gene set enrichment analysis (ssGSEA) were applied to estimate the difference of tumor microenvironment (TME) between the different risk subtypes. An eight prognostic genes (ACAP3, ATP8B3, BTK, CAV2, CDK5R1, GRIA1, PCSK9, and PLA2G3) signature was identified and divided patients into high-risk and low-risk groups. The prognostic signature was an independent prognostic factor for OS (HR > 1, p < 0.001). The molecular function analysis suggested that the signature was significantly correlated with cancer-associated pathways, including angiogenesis, epithelial mesenchymal transition, mTOR signaling, myc-targets. The low-risk patients had higher immune cell infiltration levels than high-risk group. We also evaluated the response to chemotherapeutic, targeted therapy and immunotherapy in high- and low-risk patients with LUAD. Furthermore, we validated the expression of the eight gene expression in LUAD tissues and cell lines by qRT-PCR. LYSscore signature provide a new modality for the accurate diagnosis and targeted treatment of LUAD and will help expand researchers' understanding of new prognostic models.

The Structural Proteins of Membrane Rafts, Caveolins and Flotillins, in Lung Cancer: More Than Just Scaffold Elements

Lung cancer is one of the most frequently diagnosed cancers worldwide. Due to its late diagnosis, it remains the leading cause of cancer-related deaths. Despite it is mostly associated to tobacco smoking, recent data suggested that genetic factors are of the highest importance. In this context, different processes meaningful for the development and progression of lung cancer such endocytosis, protein secretion and signal transduction, are controlled by membrane rafts. These highly ordered membrane domains contain proteins such as caveolins and flotillins, which were traditionally considered scaffold proteins but have currently been given a preponderant role in lung cancer. Here, we summarize current knowledge regarding the involvement of caveolins and flotillins in lung cancer from a molecular point of view.

Differential expression of Cadherins switch and Caveolin-2 during stages of oral carcinogenesis

Background

Oral squamous cell carcinoma (OSCC) accounts for 90% of oral malignancies, which may be preceded by oral potentially malignant disorders (OPMDs). Cancer progression involves the downregulation of epithelial markers (E-cadherin) and the upregulation of mesenchymal markers (N-cadherin), which together characterise the epithelial-mesenchymal transition (EMT). Furthermore, caveolin can act on cell adhesion and migration events that regulate the expression of the E-cadherin/α-β-catenin complex, thus favouring aggressive biological behaviour. This study aimed to analyse the immunoexpression of E-cadherin, N-cadherin and caveolin-2 at different stages of oral carcinogenesis to identify reliable biomarkers to predict malignant potential.

Methods

Expressions of E-cadherin and N-cadherin in 14 normal oral mucosae (NOM), 14 OPMD and 33 OSCC specimens were evaluated using immunohistochemistry. Clinicopathological parameters were also assessed.

Results

E-cadherin immunoexpression was significantly reduced during the progression of oral carcinogenesis (P = 0.0018). N-cadherin immunoexpression did not show any statistical differences between these groups. However, a representative number of N-cadherin-positive OSCC cases did not express E-cadherin. The expression of caveolin-2 increased significantly with the progression of the disease, from NOM to OSCC (P value: 0.0028).

Conclusion

These findings indicate that cadherin switch and caveolin-2 immunoexpression may be regulatory events in oral carcinogenesis.

CAV2 promotes the invasion and metastasis of head and neck squamous cell carcinomas by regulating S100 proteins

More than half of HNSCC patients are diagnosed with advanced disease. Locally advanced HNSCC is characterized by tumors with marked local invasion and evidence of metastasis to regional lymph nodes. CAV2 is a major coat protein of caveolins, important components of the plasma membrane. In this study, CAV2 was found to profoundly promote invasion and stimulate metastasis in vivo and in vitro. CAV2 was demonstrated to be a key regulator of S100 protein expression that upregulates the proteins levels of S100s, which promotes the invasion and migration and downregulates the expression of tumor suppressors. Mechanistically, CAV2 directly interacts with S100s in HNSCC cells, and CAV2 reduces S100A14 protein expression by promoting its ubiquitylation and subsequent degradation via the proteasome. Moreover, we discovered that CAV2 promotes the interaction between S100A14 and the E3 ubiquitin ligase TRIM29 and increases TRIM29 expression. Taken together, our findings indicate that CAV2 promotes HNSCC invasion and metastasis by regulating the expression of S100 proteins, presenting a novel potential target for anticancer therapy in HNSCC.

Elevated postischemic tissue injury and leukocyte-endothelial adhesive interactions in mice with global deficiency in caveolin-2: role of PAI-1

Ischemia/reperfusion (I/R)-induced rapid inflammation involving activation of leukocyte-endothelial adhesive interactions and leukocyte infiltration into tissues is a major contributor to postischemic tissue injury. However, the molecular mediators involved in this pathological process are not fully known. We have previously reported that caveolin-2 (Cav-2), a protein component of plasma membrane caveolae, regulated leukocyte infiltration in mouse lung carcinoma tumors. The goal of the current study was to examine if Cav-2 plays a role in I/R injury and associated acute leukocyte-mediated inflammation. Using a mouse small intestinal I/R model, we demonstrated that I/R downregulates Cav-2 protein levels in the small bowel. Further study using Cav-2-deficient mice revealed aggravated postischemic tissue injury determined by scoring of villi length in H&E-stained tissue sections, which correlated with increased numbers of MPO-positive tissue-infiltrating leukocytes determined by IHC staining. Intravital microscopic analysis of upstream events relative to leukocyte transmigration and tissue infiltration revealed that leukocyte-endothelial cell adhesive interactions in postcapillary venules, namely leukocyte rolling and adhesion were also enhanced in Cav-2-deficient mice. Mechanistically, Cav-2 deficiency increased plasminogen activator inhibitor-1 (PAI-1) protein levels in the intestinal tissue and a pharmacological inhibition of PAI-1 had overall greater inhibitory effect on both aggravated I/R tissue injury and enhanced leukocyte-endothelial interactions in postcapillary venules in Cav-2-deficient mice. In conclusion, our data suggest that Cav-2 protein alleviates tissue injury in response to I/R by dampening PAI-1 protein levels and thereby reducing leukocyte-endothelial adhesive interactions.NEW & NOTEWORTHY The role of caveolin-2 in regulating ischemia/reperfusion (I/R) tissue injury and the mechanisms underlying its effects are unknown. This study uses caveolin-2-deficient mouse and small intestinal I/R injury models to examine the role of caveolin-2 in the leukocyte-dependent reperfusion injury. We demonstrate for the first time that caveolin-2 plays a protective role from the I/R-induced leukocyte-dependent reperfusion injury by reducing PAI-1 protein levels in intestinal tissue and leukocyte-endothelial adhesive interactions in postcapillary venules.

Twist1-induced miR-199a-3p promotes liver fibrosis by suppressing caveolin-2 and activating TGF-β pathway

The activation of hepatic stellate cells (HSCs) participates in liver fibrosis, and emerging evidences indicate that microRNAs (miRNAs) are abnormally expressed during HSC activation. However, the potential roles of miRNAs in liver fibrosis still remain elusive. Therefore, this study aimed to investigate the role of miR-199a-3p in liver fibrosis and its underlying mechanism. We found that miR-199a-3p expression was dramatically upregulated during HSC activation in vitro, and during liver fibrogenesis in CCl₄-treated rats, and its liver expression was increased in the patients with cirrhosis. By the luciferase assay and RT-qPCR, we revealed that the expression of miR-199a-3p in HSCs was driven by the transcription factor Twist1 which could be further induced by TGF-β treatment. Functional studies showed that inhibition of miR-199a-3p in both human LX2 cells and rat HSCs significantly decreased the expression of fibrotic markers, such as fibronectin and connective tissue growth factor (CTGF), whereas the forced expression of miR-199a-3p exhibited opposite effects, demonstrating the role of miR-199a-3p in promoting HSC activation. Mechanistically, miR-199a-3p plays an important role in TGF-β signalling pathway activation through targeting CAV2 that negatively regulates the expression of transforming growth factor-beta receptor type I (TGFβRI). Importantly, administration of antagomiR-199a-3p in the CCl₄-treated mice significantly ameliorated hepatic fibrosis. In conclusion, Twist1-induced miR-199a-3p mediates the activation of HSCs by suppressing CAV2 expression and subsequently increasing TGFβRI expression to promote TGF-β pathway. Our findings highlight the therapeutic potential of miR-199a-3p for hepatic fibrosis.

Caveolin-2 deficiency induces a rapid anti-tumor immune response prior to regression of implanted murine lung carcinoma tumors

Immunosuppression is critical for tumor growth and metastasis as well as obstacle to effective immunotherapy. Here, we demonstrate that host deficiency in caveolin-2, a member of caveolin protein family, increases M1-polarized tumor-associated macrophage (TAM) and CD8 T cell infiltration into subcutaneously implanted murine lung carcinoma tumors. Importantly, increase in M1 TAM-specific markers and cytokines occurs prior to increased numbers of tumor-infiltrating CD8 T cells and tumor regression in caveolin-2 deficient mice, suggesting that an early increase in M1 TAMs is a novel mechanism, via which host deficiency in caveolin-2 inhibits tumor growth. Consistent with the latter, transfer and co-injection of caveolin-2 deficient bone marrow (origin of TAMs) suppresses tumor growth and increases numbers of M1-polarized TAMs in wild type mice. Collectively, our data suggest that lung cancer cells use caveolin-2 expressed in bone marrow-derived cell types including TAMs to promote tumor growth via suppressing the anti-tumor immune response and that caveolin-2 could be a potential target for cancer immunotherapy.

A novel hydrogen sulfide-releasing donor, HA-ADT, suppresses the growth of human breast cancer cells through inhibiting the PI3K/AKT/mTOR and Ras/Raf/MEK/ERK signaling pathways

Breast cancer is one of the most frequent cancers among women worldwide. Hyaluronic acid (HA) is one of the best biopolymers in terms of safety issues and has been widely used in drug delivery and tissue engineering. 5-(4-hydroxyphenyl)-3H-1,2-dithiol-3-thione (ADT-OH) is a commonly used H2S donor. In this study, we designed and synthesized a conjugate, HA-ADT, by connecting HA with ADT-OH through chemical reactions. Our results indicated that HA-ADT could produce more H2S than NaHS and GYY4137. HA-ADT exerted more potent inhibitory effects than NaHS and GYY4137 in the proliferation, viability, migration, and invasion of human breast cancer cells. Similar trends were observed in the apoptosis and the protein levels of phospho (p)-PI3K, p-AKT, p-mTOR, H-RAS, p-RAF, p-MEK, and p-ERK in human breast cancer cells. Furthermore, HA-ADT exhibited more powerful inhibitory effects on the growth of human breast cancer xenograft tumors in nude mice. In conclusion, HA-ADT could suppress the growth of human breast cancer cells through the inhibition of the PI3K/AKT/mTOR and RAS/RAF/MEK/ERK signaling pathways. HA-ADT and its derivatives might be of great potential in the treatment of different types of cancer.

Osteopontin as a multifaceted driver of bone metastasis and drug resistance

Metastasis to bone frequently occurs in majority of patients with advanced breast cancer and prostate cancer, leading to devastating skeletal-related events and substantially reducing the survival of patients. Currently, the crosstalk between tumor cells and the bone stromal compartment was widely investigated for bone metastasis and the resistance to many conventional therapeutic methods. Osteopontin (OPN), also known as SPP1 (secreted phosphoprotein 1), a secreted and chemokine-like glyco-phosphoprotein is involved in tumor progression such as cell proliferation, angiogenesis, and metastasis. The expression of OPN in tumor tissue and plasma has been clinically proved to be correlated to poor prognosis and shortened survival in patients with breast cancer and prostate cancer. This review summarizes the multifaceted roles that OPN plays in bone microenvironment and drug resistance, with emphasis on breast and prostate cancers, via binding to αvβ3 integrin and CD44 receptor and inducing signaling cascades. We further discuss the promising therapeutic strategy for OPN targeting, mainly inhibiting OPN at transcriptional or protein level or blocking it binding to receptor or its downstream signaling pathways. The comprehending of the function of OPN in bone microenvironment is crucial for the development of novel biomarker and potential therapeutic target for the diagnosis and treatment of bone metastasis and against the emergence of drug resistance in advanced cancers.

Molecular Signature of Prospero Homeobox 1 (PROX1) in Follicular Thyroid Carcinoma Cells

The prospero homeobox 1 (PROX1) transcription factor is a product of one of the lymphangiogenesis master genes. It has also been suggested to play a role in carcinogenesis, although its precise role in tumour development and metastasis remains unclear. The aim of this study was to gain more knowledge on the PROX1 function in thyroid tumorigenesis. Follicular thyroid cancer-derived cells—CGTH-W-1—were transfected with PROX1-siRNA (small interfering RNA) and their proliferation, cell cycle, apoptosis and motility were then analysed. The transcriptional signature of PROX1 depletion was determined using RNA-Sequencing (RNA-Seq) and the expression of relevant genes was further validated using reverse transcriptase quantitative PCR (RT-qPCR), Western blot and immunocytochemistry. PROX1 depletion resulted in a decreased cell motility, with both migratory and invasive potential being significantly reduced. The cell morphology was also affected, while the other studied cancer-related cell characteristics were not significantly altered. RNA-seq analysis revealed significant changes in the expression of transcripts encoding genes involved in both motility and cytoskeleton organization. Our transcriptional analysis of PROX1-depleted follicular thyroid carcinoma cells followed by functional and phenotypical analyses provide, for the first time, evidence that PROX1 plays an important role in the metastasis of thyroid cancer cells by regulating genes involved in focal adhesion and cytoskeleton organization in tumour cells.

Epigallocatechin-3-gallate inhibits the growth and increases the apoptosis of human thyroid carcinoma cells through suppression of EGFR/RAS/RAF/MEK/ERK signaling pathway

Background

Thyroid cancer is the most common type of endocrine malignancy and the incidence rate is rapidly increasing worldwide. Epigallocatechin-3-gallate (EGCG) could suppress cancer growth and induce apoptosis in many types of cancer cells. However, the mechanism of action of EGCG on the growth of human thyroid carcinoma cells has not been fully illuminated.

Methods

Cell proliferation and viability were detected by EdU and MTS assays. Cell cycle distribution was measured by flow cytometry. Migration and invasion were evaluated by scratch and transwell assays. Apoptotic levels were detected by TUNEL staining and western blotting. The protein levels of EGFR/RAS/RAF/MEK/ERK signaling pathway were detected by western blotting. The in vivo results were determined by tumor xenografts in nude mice. The in vivo proliferation, tumor microvessel density, and apoptosis were detected by immunohistochemistry.

Results

EGCG inhibited the proliferation, viability, and cell cycle progression in human thyroid carcinoma cells. EGCG decreased the migration and invasion, but increased the apoptosis of human thyroid carcinoma cells. EGCG reduced the protein levels of phospho (p)-epidermal growth factor receptor (EGFR), H-RAS, p-RAF, p-MEK1/2, and p-extracellular signal-regulated protein kinase 1/2 (ERK1/2) in human thyroid carcinoma cells. EGCG inhibited the growth of human thyroid carcinoma xenografts by inducing apoptosis and down-regulating angiogenesis.

Conclusions

EGCG could reduce the growth and increase the apoptosis of human thyroid carcinoma cells through suppressing the EGFR/RAS/RAF/MEK/ERK signaling pathway. EGCG can be developed as an effective therapeutic agent for the treatment of thyroid cancer.

CAV2 promotes the growth of renal cell carcinoma through the EGFR/PI3K/Akt pathway

Background

Caveolin-2 (CAV2) is reported to have an important role in cancer. The following study investigated the expression and function of CAV2 in kidney cancer in vitro and in vivo.

Materials and methods

Real-time PCR, immunohistochemistry and Western blotting analysis were used to determine CAV2, epidermal growth factor receptor (EGFR), phosphatidylinositol 3-kinase (PI3K) and protein kinase B (Akt) in kidney cancer cell line OS-RC-2 and clinical specimens. The role of CAV2 in maintaining kidney cancer malignant phenotype was examined by wound healing assay, Matrigel invasion assays and mouse orthotopic xenograft model.

Results

Higher expression of CAV2 was found in renal cell carcinoma tissue compared to normal tissue. Furthermore, increased expression of CAV2 was associated with cancer progression. Also, silencing of CAV2 inhibited the proliferation, migration and invasion, as well as the expression of EGFR, PI3K and p-Akt in OS-RC-2 cells in vitro, and OS-RC-2 xenograft growth in vivo.

Conclusion

Our results revealed that CAV2 promotes the growth of renal cell carcinoma through EGFR/PI3K/Akt pathway.

miR144-3p inhibits PMVECs excessive proliferation in angiogenesis of hepatopulmonary syndrome via Tie2

BACKGROUND/AIM

Increasing evidence show microRNAs (miRNAs) are associated with hepatopulmonary syndrome (HPS). The aim of this study was to investigate the role of miR-144 in the angiogenesis of HPS, as well as to identify its underlying mechanism.

METHODS

The expression levels of miR-144-3p were assessed in pulmonary micro-vascular endothelial cells (PMVECs), as well as in lung tissues from rats with HPS. We predicted the potential target of miR-144-3p. Tyrosine kinase 2(Tie2) was identified as a target gene of miR144-3p, which has an essential role in the angiogenesis of lung vessel. In addition, the effects of miR-144-3p regulated on Tie2 was examined. The upregulation and down-regulation of miR-144-3p can affect the proliferation of PMVECs.

RESULTS

We found that the levels of miR-144-3p were frequently downregulated in HPS tissues and cell lines, and overexpression of miR-144-3p dramatically inhibited PMVECs proliferation and cell cycle. We further verified the Tie2 as a novel and direct target of miR-144-3p in HPS.

CONCLUSION

miR-144-3p can negatively regulate PMVECs proliferation by Tie2 expression. In addition, overexpression of miR-144-3p may prove beneficial as a therapeutic strategy for HPS treatment.

Stroma-derived but not tumor ADAMTS1 is a main driver of tumor growth and metastasis

The matrix metalloprotease ADAMTS1 (A Disintegrin And Metalloprotease with ThromboSpondin repeats 1) has been involved in tumorigenesis although its contributions appeared ambiguous. To understand the multifaceted actions of this protease, it is still required a deeper knowledge of its implication in heterogeneous tumor-stroma interactions. Using a syngeneic B16F1 melanoma model in wild type and ADAMTS1 knockout mice we found distinct stroma versus tumor functions for this protease. Genetic deletion of ADAMTS1 in the host microenvironment resulted in a drastic decrease of tumor growth and metastasis. However, the downregulation of tumor ADAMTS1 did not uncover relevant effects. Reduced tumors in ADAMTS1 KO mice displayed a paradoxical increase in vascular density and vascular-related genes; a detailed characterization revealed an impaired vasculature, along with a minor infiltration of macrophages. In addition, ex-vivo assays supported a chief role for ADAMTS1 in vascular sprouting, and melanoma xenografts showed a relevant induction of its expression in stroma compartments. These findings provide the first genetic evidence that supports the pro-tumorigenic role of stromal ADAMTS1.

Caveolin-1 and Caveolin-2 Can Be Antagonistic Partners in Inflammation and Beyond

Caveolins, encoded by the CAV gene family, are the main protein components of caveolae. In most tissues, caveolin-1 (Cav-1) and caveolin-2 (Cav-2) are co-expressed, and Cav-2 targeting to caveolae depends on the formation of heterooligomers with Cav-1. Notwithstanding, Cav-2 has unpredictable activities, opposing Cav-1 in the regulation of some cellular processes. While the major roles of Cav-1 as a modulator of cell signaling in inflammatory processes and in immune responses have been extensively discussed elsewhere, the aim of this review is to focus on data revealing the distinct activity of Cav-1 and Cav-2, which suggest that these proteins act antagonistically to fine-tune a variety of cellular processes relevant to inflammation.

Attenuated rapid onset vasodilation with greater force production in skeletal muscle of caveolin-2-/- mice

Caveolin-2 (Cav2) is a major protein component of caveolae in membranes of vascular smooth muscle and endothelium, yet its absence alters the ultrastructure of skeletal muscle fibers. To gain insight into Cav2 function in skeletal muscle, we tested the hypothesis that genetic deletion of Cav2 would alter microvascular reactivity and depress contractile function of skeletal muscle in vivo. In the left gluteus maximus muscle (GM) of anesthetized Cav2(-/-) and wild-type (WT) male mice (age, 6 mo), microvascular responses to physiological agonists and to GM contractions were studied at 34°C. For feed arteries (FA), first- (1A), second- (2A) and third-order (3A) arterioles, respective mean diameters at rest (45, 35, 25, 12 μm) and during maximal dilation (65, 55, 45, 30 μm) were similar between groups. Cumulative dilations to ACh (10(-9) to 10(-5) M) and constrictions to norepinephrine (10(-9) to 10(-5) M) were also similar between groups, as were steady-state dilations during rhythmic twitch contractions (2 and 4 Hz; 30 s). For single tetanic contractions (100 Hz; 100, 250, and 500 ms), rapid onset vasodilation (ROV) increased with contraction duration throughout networks in GM of both groups but was reduced by nearly half in Cav2(-/-) mice compared with WT mice (P < 0.05). Nevertheless, maximal force during tetanic contraction was ∼40% greater in GM of Cav2(-/-) vs. WT mice (152 ± 14 vs. 110 ± 3 mN per square millimeter, respectively; P < 0.05). Thus, while structural and functional properties of resistance networks are well maintained in the GM of Cav2(-/-) mice, diminished ROV with greater force production reveals novel physiological roles for Cav2 in skeletal muscle.

Role of caveolin-2 in subcutaneous tumor growth and angiogenesis associated with syngeneic mouse Lewis lung carcinoma and B16 melanoma models

In addition to cancer cells, primary tumors are composed of a multitude of stromal cell types. Among others, the stromal cell types involved in tumor growth and progression include endothelial cells, fibroblasts, pericytes, stem cells and various cell types of immune origin. While the role of oncogenes or tumor suppressor proteins expressed in cancer cells has been extensively studied, far less is known about potential involvement of proteins expressed in stromal cell types present within the tumor microenvironment. Recent experimental evidence from our laboratory suggests that caveolin-2 (Cav-2) protein expressed in stromal cell types of the tumor microenvironment promotes subcutaneous tumor growth in two independent syngeneic mouse models, i.e., Lewis lung carcinoma (LLC) and B16-F10 melanoma. Mechanistically, the tumor growth promoting role of Cav-2 is associated with enhanced tumor induced neovascularization. At the molecular level, host-expressed Cav-2 appears to prevent excessive expression of anti-angiogenic thrombospondin-1 (TSP-1) and promote phosphorylation of pro-angiogenic endothelial nitric oxide synthase (eNOS) at serine 1177. Taken together, our recent findings suggest that Cav-2 expressed within the tumor microenvironment could be a potential target for anti-cancer therapy.