Caveolin-1 and prostate cancer progression

Prostate Cancer Biomarkers: From diagnosis to prognosis and precision-guided therapeutics

Prostate cancer (PCa) is one of the most commonly diagnosed malignancies and among the leading causes of cancer-related death worldwide. It is a highly heterogeneous disease, ranging from remarkably slow progression or inertia to highly aggressive and fatal disease. As therapeutic decision-making, clinical trial design and outcome highly depend on the appropriate stratification of patients to risk groups, it is imperative to differentiate between benign versus more aggressive states. The incorporation of clinically valuable prognostic and predictive biomarkers is also potentially amenable in this process, in the timely prevention of metastatic disease and in the decision for therapy selection. This review summarizes the progress that has so far been made in the identification of the genomic events that can be used for the classification, prediction and prognostication of PCa, and as major targets for clinical intervention. We include an extensive list of emerging biomarkers for which there is enough preclinical evidence to suggest that they may constitute crucial targets for achieving significant advances in the management of the disease. Finally, we highlight the main challenges that are associated with the identification of clinically significant PCa biomarkers and recommend possible ways to overcome such limitations.

Increased lysophosphatidylcholine acyltransferase 1 expression is unrelated to prognosis of esophageal cancer patients

Introduction

Lysophosphatidylcholine acyltransferase 1 (LPCAT1) has repeatedly been suggested to be associated with tumorigenesis. To evaluate the role of LPCAT1 in esophageal cancer, LPCAT1 immunostaining was analyzed on a tissue microarray containing samples from esophageal cancer patients.

Results

In benign esophageal tissue, LPCAT1 staining was detectable in low intensities. LPCAT1 staining was increased in malignant as compared to benign esophageal tissue and was found in high intensity in 26.4% of 288 interpretable esophageal adenocarcinomas (EACs) and in 23.2% of 211 squamous cell carcinomas (ESCCs). Increased LPCAT1 staining was linked to undifferentiated tumor grading in both subtypes of EACs and ESCCs (p = 0.0273 and p = 0.0085).

Conclusion

However, LPCAT1 was not associated with prognosis of EAC and ESCC patients (p = 0.6838 and p = 0.4695) and thus cannot be considered a prognostic biomarker in esophageal cancers.

Association of CAV1 polymorphisms with the risks of breast cancer: A systematic review and meta-analysis

BACKGROUND

Caveolin-1 (CAV1) polymorphisms have been shown to correlated with breast cancer risk in previous studies. However, the role of CAV1 polymorphisms still remained indecisive, and dual functions of CAV1 was demonstrated in breast cancer development. Consequently, a meta-analysis to evaluate and summarize the association of the CAV1 polymorphisms with breast cancer susceptibility.

MATERIAL AND METHODS

Extensive search was performed in PubMed, Web of Science, Google scholar, EMBASE.com, CNKI and Wanfang searching platform up to March 2019. The Newcastle-Ottawa Scale (NOS) were used to evaluate the quality of each study. The Odds ratios (ORs) and the 95% confidence intervals (CIs) were analyzed to evaluate the strength of the associations in five genetic models. Inter-study heterogeneity was quantified using the I-squared (I²) test. In addition, the Egger's test and Begg's test were applied to evaluate the publication bias.

RESULTS

4 case-control studies with 2115 cases and 2138 controls were enrolled into this analysis. There was a significant association between rs3807987 polymorphism of CAV1 and breast cancer in allele comparison (A vs. G: OR = 1.288, 95％CI = 1.162-1.428, P < 0.001), heterozygote comparison (AG vs. GG: OR= 1.422, 95％CI=1.233-1.639, P < 0.001), and dominant comparison (AA+AG vs. GG: OR=1.395, 95％CI=1.228-1.586, P < 0.001). A significant association of rs3807987 polymorphism in allele comparison (A vs. G: OR=1.238, 95％CI=1.109-1.383, P < 0.001), heterozygote comparison (AG VS. GG: OR=1.466, 95％CI=1.267-1.697, P < 0.05), and dominant comparison (AA+AG vs. GG: OR=1.384, 95％CI=1.209-1.585, P < 0.001) was also founded amongst Chinese population. A significant association between rs7804372 polymorphism and breast cancer amongst Chinese population in recessive comparison (AA vs. AT + TT: OR = 0.730, 95％CI = 0.567-0.940, P = 0.015) was identified. No significant association between breast cancer risk and rs1997623 was found.

CONCLUSION

CAV1 rs3807987 and rs7804372 polymorphisms are associated with the change of breast cancer risk. More well-designed and large studies in various populations are needed to further elaborate these associations.

Network-pharmacology-based identification of caveolin-1 as a key target of Oldenlandia diffusa to suppress breast cancer metastasis

BACKGROUND

Breast cancer remains the most common female malignancy and metastasis is the leading cause of death in breast cancer patients. Oldenlandia diffusa has been empirically and extensively used as an adjuvant therapy for metastatic breast cancer patients in Traditional Chinese Medicine (TCM) with proven efficacy. However, its anti-metastasis mechanism has been poorly revealed.

METHODS

Multiple molecular biology experiments as well as network pharmacology, bioinformatics analysis were conducted to investigate the anti-metastasis mechanism of Oldenlandia diffusa in breast cancer.

RESULTS

We demonstrated that ethanol extract of Oldenlandia diffusa (EEOD) significantly inhibited proliferation and induced apoptosis of high-metastatic breast cancer cell lines MDA-MB-231 and MDA-MB-453, while having no obvious cytotoxic effect on multiple nonmalignant cells. Furthermore, EEOD remarkably suppressed the migration and invasion capacities of the above breast cancer cells by modulating the matrix metalloproteinases (MMPs) and the epithelial-mesenchymal transition (EMT) pathway. More importantly, EEOD also significantly inhibited breast cancer metastasis in zebrafish xenotransplantation model in vivo. Network pharmacology and bioinformatics analysis further demonstrated that EEOD yielded 12 candidate compounds and 225 potential targets, and shared 85 putative targets associated with breast cancer metastasis. Mechanistically, RNA sequencing and experimental validation results suggested that EEOD might inhibit breast cancer metastasis by attenuating the expression of caveolin-1 (Cav-1) as overexpression of Cav-1 could weaken the anti-metastasis efficacy of EEOD.

CONCLUSIONS

Overall, our findings proved that EEOD could inhibit breast cancer metastasis by attenuating the expression of Cav-1, highlighting the use of EEOD as an adjunctive therapy for metastatic breast cancer patients. This study also provides novel insights into network pharmacology and bioinformatics analysis as effective tools to illuminate the scientific basis of TCM.

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.

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.

Caveolin-1 expression as a prognostic marker in triple negative breast cancers of Asian women

BACKGROUND

Triple-negative breast cancers (TNBCs) are defined by their lack of oestrogen receptor, progesterone receptor and epidermal growth factor receptor 2. Although heterogeneous, the majority are aggressive and treatment options are limited. Caveolin acts as tumour suppressor or promoter depending on the cancer type.

AIM

In this study, we aimed to determine if the expression levels of the candidate biomarker caveolin-1 on stromal or tumour cells were associated with clinicopathological parameters and disease outcomes in TNBCs from an ethnically diverse cohort of Asian women.

METHODS

Tumour specimens from 699 women with TNBC were subjected to immunohistochemical analysis of the frequency and intensity of caveolin-1 expression in tumour and stromal cells. A subset of 141 tumour samples also underwent Nanostring measurement of CAV1 mRNA. Results were correlated with clinicopathological parameters and disease outcomes.

RESULTS

Expression of caveolin-1 in stromal cells was observed in 14.4% of TNBC cases. TNBCs of the basal-like phenotype (85% of samples) were significantly more likely to exhibit stromal cell caveolin-1 expression (p=0.028), as were those with a trabecular growth pattern (p=0.007). Lack of stromal caveolin-1 expression in both TNBCs and those with the basal-like phenotype was significantly associated with worse overall survival (p=0.009 and p=0.026, respectively): accordingly, increasing mRNA levels of CAV1 in TNBC samples predicted better overall survival. Caveolin-1 expression on TNBC tumour cells was not associated with clinical outcome.

CONCLUSION

Stromal, but not tumoural, caveolin-1 expression is significantly associated with survival in Asian women with TNBC.

Extracellular vesicles for liquid biopsy in prostate cancer: where are we and where are we headed?

Background:

Extracellular vesicles (EVs) are a heterogeneous class of lipid bound particles shed by any cell in the body in physiological and pathological conditions. EVs play critical functions in intercellular communication. EVs can actively travel in intercellular matrices and eventually reach the circulation. They can also be released directly in biological fluids where they appear to be stable. Because the molecular content of EVs reflects the composition of the cell of origin, they have recently emerged as a promising source of biomarkers in a number of diseases. EV analysis is particularly attractive in cancer patients that frequently present with increased numbers of circulating EVs.

Methods:

We sought to review the current literature on the molecular profile of prostate cancer-derived EVs in model systems and patient biological fluids in an attempt to draw some practical and universal conclusions on the use of EVs as a tool for liquid biopsy in clinical specimens.

Results:

We discuss advantages and limitations of EV-based liquid biopsy approaches summarizing salient studies on protein, DNA and RNA. Several candidate biomarkers have been identified so far but these results are difficult to apply to the clinic. However, the field is rapidly moving toward the implementation of novel tools to isolate cancer-specific EVs that are free of benign EVs and extra-vesicular contaminants. This can be achieved by identifying markers that are exquisitely present in tumor cell-derived EVs. An important contribution might also derive from a better understanding of EV types that may play specific functions in tumor progression and that may be a source of cancer-specific markers.

Conclusions:

EV analysis holds strong promises for the development of non-invasive biomarkers in patients with prostate cancer. Implementation of modern methods for EV isolation and characterization will enable to interrogate circulating EVs in vivo.

Progression-related loss of stromal Caveolin 1 levels fosters the growth of human PC3 xenografts and mediates radiation resistance

Despite good treatment results in localized prostate tumors, advanced disease stages usually have a pronounced resistance to chemotherapy and radiotherapy. The membrane protein caveolin-1 (Cav1) functions here as an important oncogene. Therefore we examined the impact of stromal Cav1 expression for tumor growth and sensitivity to ionizing radiation (IR). Silencing of Cav1 expression in PC3 cells resulted in increased tumor growth and a reduced growth delay after IR when compared to tumors generated by Cav1-expressing PC3 cells. The increased radiation resistance was associated with increasing amounts of reactive tumor stroma and a Cav1 re-expression in the malignant epithelial cells. Mimicking the human situation these results were confirmed using co-implantation of Cav1-silenced PC3 cells with Cav1-silenced or Cav1-expressing fibroblasts. Immunohistochemically analysis of irradiated tumors as well as human prostate tissue specimen confirmed that alterations in stromal-epithelial Cav1 expressions were accompanied by a more reactive Cav1-reduced tumor stroma after radiation and within advanced prostate cancer tissues which potentially mediates the resistance to radiation treatment. Conclusively, the radiation response of human prostate tumors is critically regulated by Cav1 expression in stromal fibroblasts. Loss of stromal Cav1 expression in advanced tumor stages may thus contribute to resistance of these tumors to radiotherapy.

p53 as a Regulator of Lipid Metabolism in Cancer

Enhanced proliferation and survival are common features of cancer cells. Cancer cells are metabolically reprogrammed which aids in their survival in nutrient-poor environments. Indeed, changes in metabolism of glucose and glutamine are essential for tumor progression. Thus, metabolic reprogramming is now well accepted as a hallmark of cancer. Recent findings suggest that reprogramming of lipid metabolism also occurs in cancer cells, since lipids are used for biosynthesis of membranes, post-translational modifications, second messengers for signal transduction, and as a source of energy during nutrient deprivation. The tumor suppressor p53 is a transcription factor that controls the expression of proteins involved in cell cycle arrest, DNA repair, apoptosis, and senescence. p53 also regulates cellular metabolism, which appears to play a key role in its tumor suppressive activities. In this review article, we summarize non-canonical functions of wild-type and mutant p53 on lipid metabolism and discuss their association with cancer progression.

High Caveolin-1 Expression in Tumor Stroma Is Associated with a Favourable Outcome in Prostate Cancer Patients Managed by Watchful Waiting

In the present study we have investigated whether Caveolin-1 expression in non-malignant and malignant prostate tissue is a potential prognostic marker for outcome in prostate cancer patients managed by watchful waiting. Caveolin-1 was measured in prostate tissues obtained through transurethral resection of the prostate from 395 patients diagnosed with prostate cancer. The majority of the patients (n = 298) were followed by watchful waiting after diagnosis. Tissue microarrays constructed from malignant and non-malignant prostate tissue were stained with an antibody against Caveolin-1. The staining pattern was scored and related to clinicopathologic parameters and outcome. Microdissection and qRT-PCR analysis of Cav-1 was done of the prostate stroma from non-malignant tissue and stroma from Gleason 3 and 4 tumors. Cav-1 RNA expression was highest in non-malignant tissue and decreased during cancer progression. High expression of Caveolin-1 in tumor stroma was associated with significantly longer cancer specific survival in prostate cancer patients. This association remained significant when Gleason score and local tumor stage were combined with Caveolin-1 in a Cox regression model. High stromal Caveolin-1 immunoreactivity in prostate tumors is associated with a favourable prognosis in prostate cancer patients managed by watchful waiting. Caveolin-1 could possibly become a useful prognostic marker for prostate cancer patients that are potential candidates for active surveillance.

Gene Expression Profiling of Prostate Cancer–Associated Genes Identifies Fibromodulin as Potential Novel Biomarker for Prostate Cancer

Background

The aim of this study was to evaluate the gene expression profiles of a set of prostate cancer–associated genes in prostate cancer cell lines, to determine their association with different cancer phenotypes and identify potential novel biomarkers for this disease.

Methods

Quantitative real-time PCR was used to determine the expression profiles of 21 prostate cancer–associated genes in the human prostate cancer cell lines PC-3 and LNCaP, using the nontumorigenic cell line PWR-1E as control cell line. Genes evaluated were ESM-1, SERPINE2, CLU, BGN, A2M, PENK, FMOD, CD81, DCN, TSPAN8, KBTBD10, F2RL1, TMSB4X, SNCG, CXXC5, FOXQ1, PDPN, SPN, CAV1, CD24 and KLK3. A potential biomarker from this set of genes, the FMOD gene, encoding the small leucine-rich proteoglycan fibromodulin, was selected for further evaluation in clinical samples from patients diagnosed with benign or malignant prostatic disease.

Results

Several of the evaluated genes showed significantly altered expression in the prostate cancer cell lines, compared with nontumorigenic PWR-1E cells. Further evaluation of FMOD transcript in prostate clinical samples from patients diagnosed with benign or malignant prostatic disease identified a significant difference in the expression levels of this proteoglycan between benign and malignant tissue (p<0.05).

Conclusions

A number of gene transcripts were differentially expressed by the cell lines assayed. Among them, FMOD was further evaluated in clinical samples and was found to be differentially expressed between benign and prostate cancer tissue. Further validation of FMOD transcript in a larger population is required to ascertain its usefulness as biomarker for prostate cancer.

Pigment epithelium-derived factor inhibits caveolin-induced interleukin-8 gene expression and proliferation of human prostate cancer cells

Caveolin-1 (Cav), a primary protein component of caveolae, is overexpressed in prostate cancer, thereby promoting growth and metastasis of this tumor. By contrast, pigment epithelium-derived factor (PEDF) has been shown to inhibit tumor growth and metastasis, including that of prostate cancer, via its anti-angiogenic and anti-inflammatory effects. Although it was recently demonstrated that PEDF binds to Cav and blocks its pro-inflammatory actions in endothelial cells, it remains unclear whether PEDF also inhibits the tumor-promoting effects of Cav in cultured prostate cancer cells. The present study examined the effects of PEDF on cell growth, in addition to the gene expression of interleukin-8 (IL-8), which is involved in prostate cancer progression, in the PC-3 human prostate cancer cell line. Exogenous Cav led to a dose-dependent upregulation of the mRNA expression of IL-8 in PC-3 cells, which was blocked by treatment with 1 or 10 nM PEDF, or following the overexpression of small interfering RNAs directed against Cav. Cav (10 nM) increased DNA synthesis in PC-3 cells, which was again suppressed by the administration of 10 nM PEDF. The results of the present study indicated that PEDF may inhibit Cav-induced increases in IL-8 gene expression and proliferation of PC-3 cells. Therefore, the suppressive effects of PEDF in prostate cancer may, in part, be ascribed to its inhibitory actions on Cav.

CAVEOLIN-1 expression in brain metastasis from lung cancer predicts worse outcome and radioresistance, irrespective of tumor histotype

Brain metastases develop in one-third of patients with non-small-cell lung cancer and are associated with a dismal prognosis, irrespective of surgery or chemo-radiotherapy. Pathological markers for predicting outcomes after surgical resection and radiotherapy responsiveness are still lacking. Caveolin 1 has been associated with chemo- and radioresistance in various tumors, including non-small-cell lung cancer. Here, caveolin 1 expression was assessed in a series of 69 brain metastases from non-small-cell lung cancer and matched primary tumors to determine its role in predicting survival and radiotherapy responsiveness. Only caveolin 1 expression in brain metastasis was associated with poor prognosis and an increased risk of death (log rank test, p = 0.015). Moreover, in the younger patients (median age of <54 years), caveolin 1 expression neutralized the favorable effect of young age on survival compared with the older patients. Among the radiotherapy-treated patients, an increased risk of death was detected in the group with caveolin 1-positive brain metastasis (14 out of 22 patients, HR=6.839, 95% CI 1.849 to 25.301, Wald test p = 0.004). Overall, caveolin 1 expression in brain metastasis from non-small-cell lung cancer is independently predictive of worse outcome and radioresistance and could become an additional tool for personalized therapy in the critical subset of brain-metastatic non-small-cell lung cancer patients.

γ-Oryzanol reduces caveolin-1 and PCGEM1 expression, markers of aggressiveness in prostate cancer cell lines

BACKGROUND

Prostate cancer is a leading cause of death among men due to the limited number of treatment strategies available for advanced disease. γ-oryzanol is a component of rice bran, rich in phytosterols, known for its antioxidant, anti-carcinogenic and endocrinological effects. It is known that γ-oryzanol may affect prostate cancer cells through the down regulation of the antioxidant genes and that phytosterols have anti-proliferative and apoptotic effects. There are evidences showing that some of the components of γ-oryzanol can modulate genes involved in the development and progression of prostate cancer, as caveolin-1 (Cav-1) and prostate specific androgen-regulated gene (PCGEM1).

METHODS

To determine the effects of γ-oryzanol on prostate cancer cell survival we evaluated the cell viability and biomass by MTT and sulforhodamine B assays, respectively. Cell death, cell cycle and pERK1/2 activity were assessed by flow cytometry. The changes in gene expression involved in the survival and progression of prostate cancer cav-1 and PCGEM1 genes were evaluated by quantitative real time reverse transcriptase polymerase chain reaction (RT-PCR) and cav-1 protein by immunofluorescence followed by confocal microscopy analysis.

RESULTS

We found that γ-oryzanol decreases cell viability and culture biomass by apoptosis and/or necrosis death in androgen unresponsive (PC3 and DU145) and responsive (LNCaP) cell lines, and signals through pERK1/2 in LNCaP and DU145 cells. γ-oryzanol also appears to block cell cycle progression at the G2/M in PC3 and LNCaP cells and at G0/G1 in DU145 cells. These effects were accompanied by a down regulation in the expression of the cav-1 in both androgen unresponsive cell lines and PCGEM1 gene in DU145 and LNCaP cells.

CONCLUSION

In summary, we used biochemical and genetics approaches to demonstrate that γ-oryzanol show a promising adjuvant role in the treatment of prostate cancer.

Endothelial Caveolin-1 regulates the radiation response of epithelial prostate tumors

The membrane protein caveolin-1 (Cav1) recently emerged as a novel oncogene involved in prostate cancer progression with opposed regulation in epithelial tumor cells and the tumor stroma. Here we examined the role of stromal Cav1 for growth and radiation response of MPR31-4 prostate cancer xenograft tumors using Cav1-deficient C57Bl/6 mice. Syngeneic MPR31-4 tumors grew faster when implanted into Cav1-deficient mice. Increased tumor growth on Cav1-deficient mice was linked to decreased integration of smooth muscle cells into the wall of newly formed blood vessels and thus with a less stabilized vessel phenotype compared with tumors from Cav1 wild-type animals. However, tumor growth delay of MPR31-4 tumors grown on Cav1 knockout mice to a single high-dose irradiation with 20 Gray was more pronounced compared with tumors grown on wild-type mice. Increased radiation-induced tumor growth delay in Cav1-deficient mice was associated with an increased endothelial cell apoptosis. In vitro studies using cultured endothelial cells (ECs) confirmed that the loss of Cav1 expression increases sensitivity of ECs to radiation-induced apoptosis and reduces their clonogenic survival after irradiation. Immunohistochemical analysis of human tissue specimen further revealed that although Cav1 expression is mostly reduced in the tumor stroma of advanced and metastatic prostate cancer, the vascular compartment still expresses high levels of Cav1. In conclusion, the radiation response of MPR31-4 prostate tumors is critically regulated by Cav1 expression in the tumor vasculature. Thus, Cav1 might be a promising therapeutic target for combinatorial therapies to counteract radiation resistance of prostate cancer at the level of the tumor vasculature.

Estrogen receptor β exon 3-deleted mouse: The importance of non-ERE pathways in ERβ signaling

In 1998, an estrogen receptor β (ERβ) knockout (KO) mouse was created by interrupting the gene at the DNA binding domain (DBD) with a neocassette. The mutant females were subfertile and there were abnormalities in the brain, prostate, lung, colon, and immune system. In 2008, another ERβ mutant mouse was generated by deleting ERβ exon 3 which encodes the first zinc finger in the DBD. The female mice of this strain were unable to ovulate but were otherwise normal. The differences in the phenotypes of the two KO strains, have led to questions about the physiological function of ERβ. In the present study, we created an ERβ exon 3-deleted mouse (ERβ-Δex3) and confirmed that the only observable defect was anovulation. Despite the two in-frame stop codons introduced by splicing between exons 2 and 4, an ERβ protein was expressed in nuclei of prostate epithelial cells. Using two different anti-ERβ antibodies, we showed that an in-frame ligand binding domain and C terminus were present in the ERβ-Δex3 protein. Moreover, with nuclear extracts from ERβ-Δex3 prostates, there was an ERβ-dependent retardation of migration of activator protein-1 response elements in EMSA. Unlike the original knockout mouse, expression of Ki67, androgen receptor, and Dachshund-1 in prostate epithelium was not altered in the ERβ-Δex3 mouse. We conclude that very little of ERβ transcriptional activity depends on binding to classical estrogen response elements (EREs).

Multidrug resistance protein 1 localization in lipid raft domains and prostasomes in prostate cancer cell lines

BACKGROUND

One of the problems in prostate cancer (CaP) treatment is the appearance of the multidrug resistance phenotype, in which ATP-binding cassette transporters such as multidrug resistance protein 1 (MRP1) play a role. Different localizations of the transporter have been reported, some of them related to the chemoresistant phenotype.

AIM

This study aimed to compare the localization of MRP1 in three prostate cell lines (normal, androgen-sensitive, and androgen-independent) in order to understand its possible role in CaP chemoresistance.

METHODS

MRP1 and caveolae protein markers were detected using confocal microscopy, performing colocalization techniques. Lipid raft isolation made it possible to detect these proteins by Western blot analysis. Caveolae and prostasomes were identified by electron microscopy.

RESULTS

We show that MRP1 is found in lipid raft fractions of tumor cells and that the number of caveolae increases with malignancy acquisition. MRP1 is found not only in the plasma membrane associated with lipid rafts but also in cytoplasmic accumulations colocalizing with the prostasome markers Caveolin-1 and CD59, suggesting that in CaP cells, MRP1 is localized in prostasomes.

CONCLUSION

We hypothesize that the presence of MRP1 in prostasomes could serve as a reservoir of MRP1; thus, taking advantage of the release of their content, MRP1 could be translocated to the plasma membrane contributing to the chemoresistant phenotype. The presence of MRP1 in prostasomes could serve as a predictor of malignancy in CaP.

Caveolin-1 limits the contribution of BKCa channel to MCF-7 breast cancer cell proliferation and invasion

Increasing evidence suggests that caveolin-1 and large conductance Ca²⁺-activated potassium (BKCa) channels are implicated in the carcinogenesis processes, including cell proliferation and invasion. These two proteins have been proven to interact with each other in vascular endothelial and smooth muscle cells and modulate vascular contractility. In this study, we investigated the probable interaction between caveolin-1 and BKCa in MCF-7 breast cancer cells. We identified that caveolin-1 and BKCa were co-localized and could be reciprocally co-immunoprecipitated in human breast cancer MCF-7 cells. siRNA mediated caveolin-1 knockdown resulted in activation and increased surface expression of BKCa channel, and subsequently promoted the proliferation and invasiveness of breast cancer cells. These effects were attenuated in the presence of BKCa-siRNA. Conversely, up-regulated caveolin-1 suppressed function and surface expression of BKCa channel and exerted negative effects on breast cancer cell proliferation and invasion. Similarly, these opposing effects were abrogated by BKCa up-regulation. Collectively, our findings suggest that BKCa is a critical target for suppression by caveolin-1 in suppressing proliferation and invasion of breast cancer cells. The functional complex of caveolin-1 and BKCa in the membrane microdomain may be served as a potential therapeutic target in breast cancer.

Differential expression of caveolin-1 in human myometrial and uterine leiomyoma smooth muscle

OBJECTIVE

Uterine leiomyomas, the most common neoplasms of the female genital tract, are benign tumors of the uterus arising from the smooth muscle cells (SMCs) of the myometrium with an involvement of estrogen. Caveolin-1 (Cav-1), a major protein component in caveolae membrane lipid rafts, is down-regulated in several estrogen-related cancer cells, and overexpression of Cav-1 inhibits proliferation of cancer cells and vascular SMCs as well. Therefore, we hypothesize that Cav-1 is down-regulated in human uterine leiomyoma.

RESULTS

Western blot using tissues from clinical patients showed that Cav-1 expression was significantly lower or undetectable in uterine leiomyoma compared with their matched myometrium (P < .001). This finding was confirmed by immunohistochemistry and confocal microscopy. The cav-1 mRNA level in uterine leiomyomas was also significantly lower as detected by reverse transcription-quantitative polymerase chain reaction analysis (P = .001). To further study the underlying mechanism, we performed primary cell culture, and found that the expression of Cav-1 remained low in cultured leiomyoma SMCs (P = .009). Serum withdrawal did not change Cav-1 expression in leiomyoma SMCs, but increased expression in myometrial SMCs (P = .006). 17-β estradiol inhibited the expression of Cav-1 protein (P = .047) and mRNA (P = .007) in leiomyoma SMCs, whereas it stimulated expression in myometrial SMCs (P = .043). 17-β estradiol, although activating the mitogen-activated protein kinase pathway in both SMCs, did not stimulate their proliferation.

CONCLUSION

We conclude that human uterine leiomyomas in vitro express low levels of Cav-1, which may result from estrogen inhibition. This effect of estrogen may contribute to the pathogenesis of uterine leiomyoma. Further studies in vivo are needed to verify these results.

Expression profiles and functional associations of endogenous androgen receptor and caveolin-1 in prostate cancer cell lines

BACKGROUND

In prostate cancer (PCa) patients, the protein target for androgen deprivation and blockade therapies is androgen receptor (AR). AR interacts with many proteins that function to either co-activate or co-repress its activity. Caveolin-1 (Cav-1) is not found in normal prostatic epithelium, but is found in PCa, and may be an AR co-regulator protein.

METHODS

We investigated cell line-specific signatures and associations of endogenous AR and Cav-1 in six PCa cell lines of known androgen sensitivity: LNCaP (androgen sensitive); 22Rv1 (androgen responsive); PC3, DU145, and ALVA41 (androgen non-reliant); and RWPE1 (non-malignant). Protein and mRNA expression profiles were compared and electron microscopy used to identify cells with caveolar structures. For cell lines expressing both AR and Cav-1, knockdown techniques using small interfering RNA against AR or Cav-1 were used to test whether diminished expression of one affected the other. Co-sedimentation of AR and Cav-1 was used to test their association. A reporter assay for AR genomic activity was utilized following Cav-1 knockdown.

RESULTS

AR-expressing LNCaP and 22Rv1 cells had low endogenous Cav-1 mRNA and protein. Cell lines that expressed little or no AR (DU145, PC3, ALVA41, and RWPE1) expressed high endogenous levels of Cav-1. AR knockdown in LNCaP cells had little effect on Cav-1, but Cav-1 knockdown inhibited AR expression and genomic activity.

CONCLUSIONS

These data show endogenous AR and Cav-1 mRNA and protein expression is inversely related in PCa cells, with Cav-1 acting on the androgen/AR signaling axis possibly as an AR co-activator, demonstrated by diminished AR genomic activity following Cav-1 knockdown.

The Multifunctional Protein Kinase C-ε in Cancer Development and Progression

The protein kinase C (PKC) family proteins are important signal transducers and have long been the focus of cancer research. PKCɛ, a member of this family, is overexpressed in most solid tumors and plays critical roles in different processes that lead to cancer development. Studies using cell lines and animal models demonstrated the transforming potential of PKCɛ. While earlier research established the survival functions of PKCɛ, recent studies revealed its role in cell migration, invasion and cancer metastasis. PKCɛ has also been implicated in epithelial to mesenchymal transition (EMT), which may be the underlying mechanism by which it contributes to cell motility. In addition, PKCɛ affects cell-extracellular matrix (ECM) interactions by direct regulation of the cytoskeletal elements. Recent studies have also linked PKCɛ signaling to cancer stem cell functioning. This review focuses on the role of PKCɛ in different processes that lead to cancer development and progression. We also discussed current literatures on the pursuit of PKCɛ as a target for cancer therapy.

TGF-β cascade regulation by PPP1 and its interactors -impact on prostate cancer development and therapy

Protein phosphorylation is a key mechanism by which normal and cancer cells regulate their main transduction pathways. Protein kinases and phosphatases are precisely orchestrated to achieve the (de)phosphorylation of candidate proteins. Indeed, cellular health is dependent on the fine-tune of phosphorylation systems, which when deregulated lead to cancer. Transforming growth factor beta (TGF-β) pathway involvement in the genesis of prostate cancer has long been established. Many of its members were shown to be hypo- or hyperphosphorylated during the process of malignancy. A major phosphatase that is responsible for the vast majority of the serine/threonine dephosphorylation is the phosphoprotein phosphatase 1 (PPP1). PPP1 has been associated with the dephosphorylation of several proteins involved in the TGF-β cascade. This review will discuss the role of PPP1 in the regulation of several TGF-β signalling members and how the subversion of this pathway is related to prostate cancer development. Furthermore, current challenges on the protein phosphatases field as new targets to cancer therapy will be addressed.

Intersectin-1s: an important regulator of cellular and molecular pathways in lung injury

Abstract Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe syndromes resulting from the diffuse damage of the pulmonary parenchyma. ALI and ARDS are induced by a plethora of local or systemic insults, leading to the activation of multiple pathways responsible for injury, resolution, and repair or scarring of the lungs. Despite the large efforts aimed at exploring the roles of different pathways in humans and animal models and the great strides made in understanding the pathogenesis of ALI/ARDS, the only viable treatment options are still dependent on ventilator and cardiovascular support. Investigation of the pathophysiological mechanisms responsible for initiation and resolution or advancement toward lung scarring in ALI/ARDS animal models led to a better understanding of the disease's complexity and helped in elucidating the links between ALI and systemic multiorgan failure. Although animal models of ALI/ARDS have pointed out a variety of new ideas for study, there are still limited data regarding the initiating factors, the critical steps in the progression of the disease, and the central mechanisms dictating its resolution or progression to lung scarring. Recent studies link deficiency of intersectin-1s (ITSN-1s), a prosurvival protein of lung endothelial cells, to endothelial barrier dysfunction and pulmonary edema as well as to the repair/recovery from ALI. This review discusses the effects of ITSN-1s deficiency on pulmonary endothelium and its significance in the pathology of ALI/ARDS.

High lysophosphatidylcholine acyltransferase 1 expression independently predicts high risk for biochemical recurrence in prostate cancers

Lysophosphatidylcholine acyltransferase 1 (LPCAT1) has been suggested to play a role in cancer. To assess its role in prostate cancer, LPCAT1 expression was analyzed on a tissue microarray containing samples from 11,152 prostate cancer patients. In benign prostate glands, LPCAT1 immunostaining was absent or weak. In prostate cancer, LPCAT1 positivity was found in 73.8% of 8786 interpretable tumors including 29.2% with strong expression. Increased LPCAT1 expression was associated with advanced tumor stage (pT3b/T4) (p < 0.0001), high Gleason score (≥4 + 4) (p < 0.0001), positive nodal involvement (p = 0.0002), positive surgical margin (p = 0.0005), and early PSA recurrence (p < 0.0001). High LPCAT1 expression was strongly linked to ERG-fusion type prostate cancer. Strong LPCAT1 staining was detected in 45.3% of ERG positive but in only 16.7% of ERG negative tumors (p < 0.0001). Within ERG negative cancers, LPCAT1 staining was strongly increased within the subgroup of PTEN deleted cancers (p < 0.0001). Further subgroup analyses revealed that associations of high LPCAT1 expression with PSA recurrence and unfavorable tumor phenotype were largely driven by ERG negative cancers (p < 0.0001) while these effects were substantially mitigated in ERG positive cancers (p = 0.0073). The prognostic impact of LPCAT1 expression was independent of histological and clinical parameters. It is concluded, that LPCAT1 measurement, either alone or in combination, may be utilized for better clinical decision-making. These data also highlight the potentially important role of lipid metabolism in prostate cancer biology.

Loss of caveolin-1 in prostate cancer stroma correlates with reduced relapse-free survival and is functionally relevant to tumour progression

Levels of caveolin-1 (Cav-1) in tumour epithelial cells increase during prostate cancer progression. Conversely, Cav-1 expression in the stroma can decline in advanced and metastatic prostate cancer. In a large cohort of 724 prostate cancers, we observed significantly decreased levels of stromal Cav-1 in concordance with increased Gleason score (p = 0.012). Importantly, reduced expression of Cav-1 in the stroma correlated with reduced relapse-free survival (p = 0.009), suggesting a role for stromal Cav-1 in inhibiting advanced disease. Silencing of Cav-1 by shRNA in WPMY-1 prostate fibroblasts resulted in up-regulation of Akt phosphorylation, and significantly altered expression of genes involved in angiogenesis, invasion, and metastasis, including a > 2.5-fold increase in TGF-β1 and γ-synuclein (SNCG) gene expression. Moreover, silencing of Cav-1 induced migration of prostate cancer cells when stromal cells were used as attractants. Pharmacological inhibition of Akt caused down-regulation of TGF-β1 and SNCG, suggesting that loss of Cav-1 in the stroma can influence Akt-mediated signalling in the tumour microenvironment. Cav-1-depleted stromal cells exhibited increased levels of intracellular cholesterol, a precursor for androgen biosynthesis, steroidogenic enzymes, and testosterone. These findings suggest that loss of Cav-1 in the tumour microenvironment contributes to the metastatic behaviour of tumour cells by a mechanism that involves up-regulation of TGF-β1 and SNCG through Akt activation. They also suggest that intracrine production of androgens, a process relevant to castration resistance, may occur in the stroma.

Current status of biomarkers for prostate cancer

Prostate cancer (PCa) is a leading cause of cancer-related death of men globally. Since its introduction, there has been intense debate as to the effectiveness of the prostate specific antigen (PSA) test as a screening tool for PCa. It is now evident that the PSA test produces unacceptably high rates of false positive results and is not prognostic. Here we review the current status of molecular biomarkers that promise to be prognostic and that might inform individual patient management. It highlights current efforts to identify biomarkers obtained by minimally invasive methods and discusses current knowledge with regard to gene fusions, mRNA and microRNAs, immunology, and cancer-associated microparticles.

Phenotypic characterization of human prostatic stromal cells in primary cultures derived from human tissue samples

Emerging evidence has shown that the tumor microenvironment plays a crucial role in prostate cancer (PCa) development and progression. However, the mechanism(s) through which stromal cells regulate epithelial cells and the differences among prostatic stromal cells of different histological/pathological origin in PCa progression remain unclear. Therefore, it is necessary to characterize the stromal cell populations present in benign prostatic hyperplasia (BPH) and PCa. To this end, we used cultures from stromal cells obtained from BPH-derived (15 cases) and PCa-derived (30 cases) primary cultures. In culture, stromal cells are a mixture of fibroblasts, myofibroblasts (MFs) and muscle cells. Fibroblasts are characterized for the expression of vimentin, MFs for the co-expression of α-smooth muscle actin (α-SMA) and vimentin, whereas muscle cells for the expression of α-SMA and desmin. Fibroblasts were present in large amounts in the BPH- compared to the PCa-derived cultures, whereas MFs were more representative of PCa- as opposed to BPH-derived cultures. Some α-SMA-positive cells retained the expression of basal cytokeratin K14. This population was defined as myoepithelial cells and was associated with senescent cultures. The percentage of MFs was higher in high-grade compared to moderate- and low-grade PCa-derived cultures, whereas the number of myoepithelial cells was lower in high-grade compared to moderate- and low-grade PCa-derived cultures. In addition, we analyzed the expression of p75NTR, as well as the expression of matrix metalloproteinase (MMP)-2, MMP-9 and tissue inhibitors of MMPs (TIMPs). p75NTR expression was elevated in the stromal cultures derived from PCa compared to those derived from BPH and in cultures derived from cases with Gleason scores ≥7 compared to those derived from cases with Gleason scores <7, as well as in cultures with a high concentration of MFs compared to those with a high concentration of fibroblasts. MMP-2 was secreted by all primary cultures, whereas MMP-9 secretion was observed only in some PCa-derived stromal cells, when the percentage of MFs was significantly higher compared to BPH-derived cultures. TIMP1, TIMP2 and TIMP3 were secreted in elevated amounts in the BPH- compared to the PCa-derived stromal cultures, suggesting the differential regulation of extracellular matrix (ECM) degradation. When we used 22rv1 and PC3 PCa xenograft models for the isolation and characterization of murine cancer-associated fibroblasts (CAFs) we noted that the angiogenic wave was concurrent with the appearance of a reactive stroma phenotype, as determined by staining for α-SMA, vimentin, tenascin, calponin, desmin and Masson's trichrome. In conclusion, MF stromal cells from PCa participate in the progression and metastasis of PCa, modualting inflammation, angiogenesis and epithelial cancer cell proliferation.

The fat side of prostate cancer

Prostate cancer (PCa) metabolism appears to be unique in comparison with other types of solid cancers. Normal prostate cells mainly rely on glucose oxidation to provide precursors for the synthesis and secretion of citrate, resulting in an incomplete Krebs cycle and minimal oxidative phosphorylation for energy production. In contrast, during transformation, PCa cells no longer secrete citrate and they reactivate the Krebs cycle as energy source. Moreover, primary PCas do not show increased aerobic glycolysis and therefore they are not efficiently detectable with (18)F-FDG-PET. However, increased de novo lipid synthesis, strictly intertwined with deregulation in classical oncogenes and oncosuppressors, is an early event of the disease. Up-regulation and increased activity of lipogenic enzymes (including fatty acid synthase and choline kinase) occurs throughout PCa carcinogenesis and correlates with worse prognosis and poor survival. Thus, lipid precursors such as acetate and choline have been successfully used as alternative tracers for PET imaging. Lipid synthesis intermediates and FA catabolism also emerged as important players in PCa maintenance. Finally, epidemiologic studies suggested that systemic metabolic disorders including obesity, metabolic syndrome, and diabetes as well as hypercaloric and fat-rich diets might increase the risk of PCa. However, how metabolic disorders contribute to PCa development and whether dietary lipids and de novo lipids synthesized intra-tumor are differentially metabolized still remains unclear. In this review, we examine the switch in lipid metabolism supporting the development and progression of PCa and we discuss how we can exploit its lipogenic nature for therapeutic and diagnostic purposes. This article is part of a Special Issue entitled Lipid Metabolism in Cancer.

Gravity-sensitive signaling drives 3-dimensional formation of multicellular thyroid cancer spheroids

This study focused on the effects induced by a random positioning machine (RPM) on FTC-133 thyroid cancer cells and evaluated signaling elements involved in 3-dimensional multicellular tumor spheroid (MCTS) formation. The cells were cultured on the RPM, a device developed to simulate microgravity, and under static 1-g conditions. After 24 h on the RPM, MCTSs swimming in culture supernatants were found, in addition to growth of adherent (AD) cells. Cells grown on the RPM showed higher levels of NF-κB p65 protein and apoptosis than 1-g controls, a result also found earlier in endothelial cells. Employing microarray analysis, we found 487 significantly regulated transcripts belonging not only to the apoptosis pathway but also to other biological processes. Selected transcripts were analyzed with quantitative real-time PCR using the same samples. Compared with 1-g IL-6, IL-8, CD44, and OPN were significantly up-regulated in AD cells but not in MCTSs, while ERK1/2, CAV2, TLN1, and CTGF were significantly down-regulated in AD cells. Simultaneously, the expression of ERK2, IL-6, CAV2, TLN1, and CTGF was reduced in MCTSs. IL-6 protein expression and secretion mirrored its gene expression. Thus, we concluded that the signaling elements IL-6, IL-8, OPN, TLN1, and CTGF are involved with NF-κB p65 in RPM-dependent thyroid carcinoma cell spheroid formation.