Caveolin-1 In Cancer Research Articles

Extracellular matrix-specific Caveolin-1 phosphorylation on tyrosine 14 is linked to augmented melanoma metastasis but not tumorigenesis.

Caveolin-1 (CAV1) is a scaffolding protein that plays a dual role in cancer. In advanced stages of this disease, CAV1 expression in tumor cells is associated with enhanced metastatic potential, while, at earlier stages, CAV1 functions as a tumor suppressor. We recently implicated CAV1 phosphorylation on tyrosine 14 (Y14) in CAV1-enhanced cell migration. However, the contribution of this modification to the dual role of CAV1 in cancer remained unexplored. Here, we used in vitro [2D and transendothelial cell migration (TEM), invasion] and in vivo (metastasis) assays, as well as genetic and biochemical approaches to address this question in B16F10 murine melanoma cells. CAV1 promoted directional migration on fibronectin or laminin, two abundant lung extracellular matrix (ECM) components, which correlated with enhanced Y14 phosphorylation during spreading. Moreover, CAV1-driven migration, invasion, TEM and metastasis were ablated by expression of the phosphorylation null CAV1(Y14F), but not the phosphorylation mimicking CAV1(Y14E) mutation. Finally, CAV1-enhanced focal adhesion dynamics and surface expression of beta1 integrin were required for CAV1-driven TEM. Importantly, CAV1 function as a tumor suppressor in tumor formation assays was not altered by the Y14F mutation. In conclusion, our results provide critical insight to the mechanisms of CAV1 action during cancer development. Specific ECM-integrin interactions and Y14 phosphorylation are required for CAV1-enhanced melanoma cell migration, invasion and metastasis to the lung. Because Y14F mutation diminishes metastasis without inhibiting the tumor suppressor function of CAV1, Y14 phosphorylation emerges as an attractive therapeutic target to prevent metastasis without altering beneficial traits of CAV1.

Is Serum Caveolin-1 a Useful Biomarker for Progression in Patients with Colorectal Cancer?.

Colorectal cancer (CRC) is the third most common cause of cancer diagnosed in males and the second in females. Survival is strongly related to stage at diagnosis. There is an urgent need to find a noninvasive biomarker that can be commonly applied for screening diagnosis, early detection of recurrence, and monitoring of metastatic CRC. Protein caveolin-1 (CAV-1) has been known to be expressed abnormally in colon cancer and appears to contribute to aberrant signaling and protein trafficking. There are controversial results regarding the role of CAV-1 in cancer. We hypothesized that levels of CAV-1 in serum of patients with CRC might be important to estimate the progression of the disease. Therefore, the purpose of this study is to investigate whether serum CAV-1 might be used as a factor determining progression of CRC. A total of 61 patients with CRC (26 male, 35 female) and 46 controls (38 male, 8 female) were enrolled. Serum CAV-1 levels were measured by ELISA. The relationship between CAV-1 and progression-free survival (PFS) was analyzed with use of receiver operating characteristic (ROC) and Kaplan-Meier analysis. Results were given as median (95% CI). Mann-Whitney test was used for the comparison of groups. CAV-1 levels were found to be 11.5 ng/mL (10.4-12.9) in CRC and 11.9 ng/mL (10.7-14.4) in controls (p = 0.465). The serum CAV-1 levels in CRC patients with disease progression and without progression were respectively 10.0 ng/mL (8.5-11.3) and 12.2 ng/mL (11.1-14.8) (p = 0.023). In ROC analysis, if CAV-1 levels are equal or lesser than 10.73 ng/mL, it might show presence of progression with a sensitivity 73.3% and specificity 66.7% in patients with CRC (area under the ROC curve (AUC) = 0.697, p = 0.005). The mean PFS time was found to be 29.7 months (19.8-39.7, 95% CI for the mean) in patients who have CAV-1 level ≤ 10.73 ng/mL and 61.9 months (44.2-79.6) in patients who have CAV-1 level > 10.73 ng/mL [hazard ratios (HR) with 95% CI = 3.49 (1.26 - 9.68) (p = 0.017)]. Our results strongly suggest that CAV-1 levels might be used as a marker to determine progression of CRC. When considered in combination with other biomarkers of CRC, CAV-1 is clinically informative and instructive.

Elucidation of caveolin 1 both as a tumor suppressor and metastasis promoter in light of epigenetic modulators.

Caveolin-1 (CAV1) is an integral part of plasma membrane protein playing a vital role in breast cancer initiation and progression. CAV1 acts both as a tumor suppressor as well as an oncogene, and its activity is thus highly dependent on cellular environment. Keeping this fact in mind, the recent work is designed to reveal the role of CAV1 in inhibiting cancer cell progression in presence of epigenetic modulators like 5-aza-2'-deoxycytidine (AZA), trichostatin A (TSA), S-adenosyl methionine (SAM) and sulforaphane (SFN). Forced expression of CAV1 by AZA, TSA, and SFN is correlated to induction of apoptosis and inhibition of cell migration in breast cancer. In breast cancer along with promoter DNA methylation, other epigenetic mechanisms are also involved in CAV1 expression. These observations clearly provide a new scenario regarding the role of CAV1 in cancer and as a possible therapeutic target in breast cancer.

Effect of an angiotensin II type 1 receptor blocker on caveolin-1 expression in prostate cancer cells

IntroductionCaveolin-1, the major structural protein of caveolae, interacts directly with the AT1 receptor. The biological functions of caveolin-1 in cancer are compound, multifaceted, and depend on cell type, tumour grade and cancer stage. The AT1-R-caveolin complex in caveolae may coordinate angiotensin II (Ang II) induced signalling. The aim of this study was to determine the effect of the angiotensin II receptor type 1 blocker candesartan on caveolin expression in human metastatic prostate adenocarcinoma cells PC-3.Material and methodsWST-1 and BrdU assays were used as indicators of cell viability and proliferation after angiotensin II and/or candesartan stimulation. Real-time RT–PCR and western blot were used to study the effect of Ang II and/or candesartan on the expression of Cav-1 and AT1-R in PC-3 cellsResultsWe found that the expression of caveolin-1 mRNA in the PC-3 cells treated with CV was significantly decreased in comparison with the control (2.9 ±0.17, 4.7 ±0.6, p < 0.05), whereas a higher caveolin-1 mRNA expression was observed in those after Ang II treatment (6.0 ±0.43, 4.7 ±0.6, p < 0.05). Protein analysis indicate that the expression of caveolin-1 protein in the PC-3 cells treated with candesartan was significantly decreased when compared with the control (0.69 ±0.05, 1.6 ±0.12, p < 0.05), whereas higher caveolin-1 protein expression was observed after Ang II treatment (2.5 ±0.20, 1.6 ±0.12, p < 0.05).ConclusionsThese results provide new information on the action of candesartan and may improve the knowledge about AT1 receptor inhibitors, which can be potentially useful in prostate cancer therapy.

Caveolin-1 P132L Mutation in Human Cancers: 1 CAVeat to be Voiced

Caveolae are 50–100 nm flask-shaped invaginations of the plasma membrane that function as membrane organizing centers and play important roles in intracellular trafficking of cellular components (eg, lipid and cholesterol) and signal transduction.1 The CAV1 gene maps to 7q31.1 and encodes the ubiquitously expressed caveolin-1, which is an essential component of caveolae. Caveolin-1 is believed to regulate the activity of a plethora of signaling molecules highly represented in caveolae, such as H-ras, c-src, and src-like kinases; endothelial nitric oxide synthase; G-proteins and membrane-associated receptors coupled to G-proteins; or tyrosine kinase receptors including epidermal growth factor receptor.1 In normal breast tissue, caveolin-1 is expressed at high levels in adipocytes, endothelial cells, fibroblasts, and myoepithelial cells of the breast.1 Initial studies have suggested that caveolin-1 would have properties consistent with those of a tumor suppressor protein.2,3,4 A dominant negative mutation of the CAV1 gene was reported to be found in up to 20% of estrogen receptor (ER)-positive breast cancers.2,4 Surprisingly, however, CAV1 knock-out mice failed to develop any tumor.1,3 Furthermore, the presence of CAV1 gene mutations could not be independently validated.5,6,7,8,9 Concurrent with the controversies about the role of CAV1 as a tumor suppressor gene, evidence of caveolin-1 as a potential oncogene has been mounting.7,8,9,10,11,12,13,14,15 In fact, multiple independent groups have reported overexpression of caveolin-1 in aggressive subtypes of cancer,10,11,13,14,15 and even CAV1 gene amplification has been documented,14,16 although this has been shown to be a rare phenomenon. Furthermore, expression of caveolin-1 in stromal cells of breast cancer has also been shown to be associated with the outcome of breast cancer patients.17,18 Despite the interest in the tumor suppressive and oncogenic functions of caveolin-1, numerous issues remain unanswered. For instance, caveolin-1 expression in normal luminal epithelial cells of normal breast lobules and ducts remains a matter of controversy, as does the existence and prevalence of the CAV1 P132L dominant-negative mutation. In this issue of The Journal of Molecular Diagnostics, Koike et al19 have addressed the question of the prevalence of the CAV1 P132L mutation in human cancer. Using three different methods for mutation detection (ie, reverse-transcriptase direct sequencing, DNA-based direct sequencing, and cycleave PCR assay), the authors failed to detect the CAV1 P132L mutation in a large series of 409 human tumors, including 139 breast cancers [114 estrogen receptor (ER)-positive and 25 ER-negative tumors] and 270 cancers from other anatomical sites (ie, gastrointestinal tract, lung, ovary, and pancreas). Taken together, the findings reported by Koike et al19 and those by others5,6,7,8,9 call into question the presence of the CAV1 P132L mutation in breast cancers and other cancer types and heat up the debate about the roles of caveolin-1 in human cancer.

IMPACT OF CAVEOLIN-1 EXPRESSION ON CLINICOPATHOLOGICAL PARAMETERS IN RENAL CELL CARCINOMA

Caveolin-1 is a major structural component of caveolae, which are plasma membrane microdomains implicated in the regulation of intracellular signaling pathways. Previous studies of the expression and function of caveolin-1 in cancer have shown controversial results, indicating that the physiological role of caveolin-1 varies according to cancer type. We evaluated caveolin-1 expression in renal cell carcinoma and investigated its association with pathological features and clinical outcome. Caveolin-1 expression was evaluated by immunohistochemistry using rabbit polyclonal antibody against caveolin-1 in 60 paraffin embedded primary renal cell carcinoma specimens and 6 metastatic renal cell carcinoma specimens. When more than 50% of all cancer cell cytoplasm stained, the tumor was considered caveolin-1 positive. Associations between caveolin-1 expression, and pathological features and clinical outcomes were analyzed. Of 60 primary tumors 16 (26.7%) and 5 of 6 metastatic tumors (83.3%) were immunoreactive in more than 50% of cancer cells and considered caveolin-1 positive. Although no significant associations between caveolin-1 expression, pathological stage (T stage) and distant metastasis at initial presentation were observed, significant associations between positive caveolin-1 expression and high grade tumor (p = 0.0009) and regional lymph node metastasis at initial presentation (p = 0.0049) and venous invasion (p = 0.0195) were observed. There was no difference in cancer specific survival between caveolin-1 positive and negative groups. However, in 43 patients without metastasis to regional lymph nodes or a distant site at initial presentation (N0M0) the caveolin-1 positive group had significantly shorter progression-free survival than the caveolin-1 negative group (p = 0.0332). Caveolin-1 over expression could be a common finding in aggressive forms of renal cell carcinoma. Caveolin-1 might have an important role in the invasion and metastatic progression of renal cell carcinoma.

Expression of caveolin-1 is associated with poor prognosis of patients with squamous cell carcinoma of the lung

Background: Caveolin-1, as a major component of caveolae, is involved in the regulation of cell cycle by impacting various signaling pathways. Previous studies of caveolin-1 in cancer showed two contrary results. In most in vitro studies, caveolin-1 played a role as a tumor suppressor. On the other hand, the elevated expression of caveolin-1 was often reported to be associated with poor clinical outcome in human studies. These results indicate differential biological functions of caveolin-1 depending on the development and progression stage of cancer in vivo. Methods: To clarify the correlation between the clinicopathologic profiles of pulmonary squamous cell carcinomas and the expression of caveolin-1, 107 cases of formalin-fixed and paraffin-embedded tissues of pulmonary squamous cell carcinomas were immunohistochemically evaluated for the expression of caveolin-1 by the tissue-array method. Results: Caveolin-1 was expressed in 34 cases (31.7%) among 107 cases of pulmonary squamous cell carcinoma. The expression of caveolin-1 was statistically correlated with pathologic stage (stage I and II vs. III; P<0.001), pT (T1 and T2 vs. T3 and T4; P=0.001), and pN (N1 vs. N2 and N3; P=0.0143). The patients with caveolin-1 expression in pulmonary squamous cell carcinomas showed a poorer prognosis than those in caveolin-1-negative group ( P=0.0345). Conclusion: The expression of caveolin-1 is significantly correlated with advanced pathologic stage and poor prognosis in pulmonary squamous cell carcinoma. The results of current study suggest that the expression level of caveolin-1 may be a candidate factor for predicting prognosis in patients with pulmonary squamous cell carcinoma.