Caveolin-1 is a member of the caveolin family that has been ascribed a dual role in cancer. In early stages of disease the protein functions predominantly as a tumor suppressor, whereas at later ...stages, caveolin-1 expression is associated with tumor progression and metastasis. Here, some mechanisms associated with caveolin-1-dependent tumor suppression will be briefly discussed before focusing on the role of this protein and particularly phosphorylation of tyrosine-14 in promoting cell migration, invasion and metastasis. Models are provided summarizing possible explanations for these dramatic changes in function, as well as mechanisms by which this may be achieved.
Caveolins are a family of membrane proteins required for the formation of small plasma membrane invaginations called caveolae that are implicated in cellular trafficking processes. In addition to ...this structural role, these scaffolding proteins modulate numerous intracellular signaling pathways; often via direct interaction with specific binding partners. Caveolin-1 is particularly well-studied in this respect and has been attributed a large variety of functions. Thus, Caveolin-1 also represents the best-characterized isoform of this family with respect to its participation in cancer. Rather strikingly, available evidence indicates that Caveolin-1 belongs to a select group of proteins that function, depending on the cellular settings, both as tumor suppressor and promoter of cellular traits commonly associated with enhanced malignant behavior, such as metastasis and multi-drug resistance. The mechanisms underlying such ambiguity in Caveolin-1 function constitute an area of great interest. Here, we will focus on discussing how Caveolin-1 modulates cell death and survival pathways and how this may contribute to a better understanding of the ambiguous role this protein plays in cancer.
Summary
The role of caveolin‐1 (CAV1) in cancer is highly controversial. CAV1 suppresses genes that favor tumor development, yet also promotes focal adhesion turnover and migration of metastatic ...cells. How these contrasting observations relate to CAV1 function in vivo is unclear. Our previous studies implicate E‐cadherin in CAV1‐dependent tumor suppression. Here, we use murine melanoma B16F10 cells, with low levels of endogenous CAV1 and E‐cadherin, to unravel how CAV1 affects tumor growth and metastasis and to assess how co‐expression of E‐cadherin modulates CAV1 function in vivo in C57BL/6 mice. We find that overexpression of CAV1 in B16F10 (cav‐1) cells reduces subcutaneous tumor formation, but enhances metastasis relative to control cells. Furthermore, E‐cadherin expression in B16F10 (E‐cad) cells reduces subcutaneous tumor formation and lung metastasis when intravenously injected. Importantly, co‐expression of CAV1 and E‐cadherin in B16F10 (cav‐1/E‐cad) cells abolishes tumor formation, lung metastasis, increased Rac‐1 activity, and cell migration observed with B16F10 (cav‐1) cells. Finally, consistent with the notion that CAV1 participates in switching human melanomas to a more malignant phenotype, elevated levels of CAV1 expression correlated with enhanced migration and Rac‐1 activation in these cells.
A novel mouse model of gallbladder preneoplasia secondary to diet‐induced stones progresses in parallel with intense inflammation. Ezetimibe inhibits stone formation, inflammation, and ...metaplasia–dysplasia development. Aspirin does not reduce stone formation, however, ameliorates inflammation and preneoplasia onset (but only in a low‐cholesterol diet). This model recapitulates the metaplasia–dysplasia sequence observed in humans and is suitable for gallbladder carcinogenesis research.
Gallbladder stones (cholecystolithiasis) are the main risk factor for gallbladder cancer (GBC), a lethal biliary malignancy with poor survival rates worldwide. Gallbladder stones are thought to damage the gallbladder epithelium and trigger chronic inflammation. Preneoplastic lesions that arise in such an inflammatory microenvironment can eventually develop into invasive carcinoma, through mechanisms that are not fully understood. Here, we developed a novel gallbladder preneoplasia mouse model through the administration of two lithogenic diets (a low‐ or a high‐cholesterol diet) in wild‐type C57BL/6 mice over a period of 9 months. Additionally, we evaluated the chemopreventive potentials of the anti‐inflammatory drug aspirin and the cholesterol absorption inhibitor ezetimibe. Both lithogenic diets induced early formation of gallbladder stones, together with extensive inflammatory changes and widespread induction of metaplasia, an epithelial adaptation to tissue injury. Dysplastic lesions were presented only in mice fed with high‐cholesterol diet (62.5%) in late stages (9th month), and no invasive carcinoma was observed at any stage. The cholesterol absorption inhibitor ezetimibe inhibited gallbladder stone formation and completely prevented the onset of metaplasia and dysplasia in both lithogenic diets, whereas aspirin partially reduced metaplasia development only in the low‐cholesterol diet setting. This model recapitulates several of the structural and inflammatory findings observed in human cholecystolithiasic gallbladders, making it relevant for the study of gallbladder carcinogenesis. In addition, our results suggest that the use of cholesterol absorption inhibitors and anti‐inflammatory drugs can be evaluated as chemopreventive strategies to reduce the burden of GBC among high‐risk populations.
Numerous studies have proposed the use of fluorescent semiconductor nanoparticles or quantum dots (QDs) as novel tools to label cells and tumors. However, QD applications are limited by their ...toxicity in biological systems and little is known about whether QDs affect the capacity of cancer cells to metastasize. Previously, we described the "biomimetic" synthesis of CdTe-QDs (QDs-glutathione GSH) with increased biocompatibility and the potential utility in labeling cells.
In order to determine the feasibility of using QDs-GSH as a tool for tracking tumor cells during early metastasis, we characterized here for the first time, the in vitro and in vivo effects of the incorporation of green or red biomimetic QDs-GSH into B16F10 cells, a syngeneic mouse melanoma line for metastasis assays in C57BL/6 mice.
B16F10 cells were labeled with green or red biomimetic QDs-GSH in the presence or absence of n-acetylcysteine. Then, migration, invasion and proliferation of labeled B16F10 were evaluated in vitro. Finally, the B16F10 cells labeled with red QDs-GSH were used to monitor in vivo lung metastasis at early time points (5 minutes to 24 hours) or after 21 days in C57BL/6 mice.
We developed a methodology that allows obtaining QDs-GSH-labeled B16F10 cells (nearly 100% viable labeled cells), which remained viable for at least 5 days and migrated similarly to control cells. However, proliferation, invasion, and the capacity to form metastatic nodules in the lungs were severely attenuated. Fluorescence imaging revealed that distribution/accumulation of QDs-GSH-labeled B16F10 cells could be tracked following injection into C57BL/6 mice (syngeneic preclinical metastasis model) and that these cells preferentially accumulated in the perialveolar area in lungs as early as 5 minutes post-injection.
The methodology described here represents a useful alternative for monitoring initial events during tumor cell metastasis.
Elevated expression of CAV1 in breast cancer increases tumor progression. Extracellular vesicles (EVs) from CAV1-expressing MDA-MB-231 breast cancer cells contain Tenascin C (TNC), but the relevance ...of TNC remained to be defined.
EVs were characterized by nanotracking analysis, microscopy and western blotting. The uptake of EVs by cells was studied using flow cytometry. The effects of EVs on breast cancer cells were tested in migration, invasion, colony formation and
assays.
EVs were taken up by cells; however, only those containing TNC promoted invasiveness.
, EVs lacking TNC ceased to promote tumor growth.
CAV1 and TNC contained in breast cancer cell-derived EVs were identified as proteins that favor progression of breast cancer.
Caveolin-1 (CAV1) is a well-established nitric oxide synthase inhibitor, whose function as a tumor suppressor is favored by, but not entirely dependent on, the presence of E-cadherin. Tumors are ...frequently hypoxic and the activation of the hypoxia-inducible factor-1α (HIF1α) promotes tumor growth. HIF1α is regulated by several post-translational modifications, including S-nitrosylation. Here, we evaluate the mechanisms underlying tumor suppression by CAV1 in cancer cells lacking E-cadherin in hypoxia. Our main findings are that CAV1 reduced HIF activity and Vascular Endothelial Growth Factor expression in vitro and in vivo. This effect was neither due to reduced HIF1α protein stability or reduced nuclear translocation. Instead, HIF1α S-nitrosylation observed in hypoxia was diminished by the presence of CAV1, and nitric oxide synthase (NOS) inhibition by Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) reduced HIF1α transcriptional activity in cells to the same extent as observed upon CAV1 expression. Additionally, arginase inhibition by (S)-(2-Boronoethyl)-L-cysteine (BEC) partially rescued cells from the CAV1-mediated suppression of HIF1α transcriptional activity. In vivo, CAV1-mediated tumor suppression was dependent on NOS activity. In summary, CAV1-dependent tumor suppression in the absence of E-cadherin is linked to reduced HIF1α transcriptional activity via diminished NOS-mediated HIF1α S-nitrosylation.
Management of the South American tomato leafminer, Tuta absoluta Meyrick, with insecticides has led to the widespread development of insect resistance. Mass trapping using traps baited with the ...female-produced sex pheromone is an attractive alternative for the management of this pest. The current study evaluated several commercial trap designs for capture of T. absoluta. Based on its small size and ease of handling, the most effective trap is a small plastic container with entry windows cut on the sides filled with motor oil over water. These traps are most effective when placed near ground level. Tests of septa containing 0.1 or 0.2 mg of the pheromone (95:5) E4, Z8-14Ac/E4,Z8,Z11-14Ac were slightly more attractive than septa loaded with 0.5, 1.0, or 2 mg during the first week of use, but the latter three loadings were slightly more attractive than the first two loadings after 9 weeks. Ideal trap baits were loaded with 0.5 mg of pheromone. Higher numbers of T. absoluta were captured near upwind borders of tomato fields suggesting that treatments against T. absoluta should be concentrated near upwind parts of fields. Comparisons of conventional insecticide treatment versus mass trapping to manage T. absoluta damage in three different test sites showed that even when initial captures in monitoring traps were high (>35 males trap⁻¹ day⁻¹), mass trapping at 48 traps/ha reduced leaf damage more efficiently than conventional insecticide treatment. Based on the typical insecticide recommendations against T. absoluta, mass trapping is an economically viable alternative.
Background: MicroRNA-335-5p (miR-335) has been reported to be dysregulated in various types of cancer, including gastric cancer (GC). Recently, we have shown the downregulation of miR-335 in GC ...tissues relative to their paired adjacent non-tumour tissues. We have also demonstrated that miR-335 is downregulated in plasma samples from GC patients. Here, we aimed to investigate the expression of miR-335 in GC derived extracellular vesicles (EVs) in plasma. Moreover, we focused on exosomes loaded with miR-335, their effect after incorporation in GC cells, and their biodistribution in vivo. Methods: EVs were isolated from a cohort of 12 plasma patients' samples, from supernatants from two GC cell lines, a primary tumour derived cell line AGS and metastatic derived cell line HS746T, and from cells transfected with miR-335 mimics and characterized by western blot and nanosight. MiR-335 expression levels in plasma EVs, cell lines, transfected cells and their EVs, as well as expression of target genes of miR-335, were analysed by qPCR. Incorporation of EVs into cells was quantified by flow cytometry. In biodistribution studies, EVs were labeled with fluorescent dye DiR, injected intravenously in the tail of mice (3 per condition) and their distribution in time was evaluated using in vivo visualizing machine. Brain, heart, lung, spleen, kidney, liver, stomach, colon, intestine and bone marrow were evaluated. Plasma samples were obtained with written informed consent from patients. Animal studies were approved by ethical committee. Results: Our cohort of patients show a tendency that plasma EVs isolated from GC patients contain less miR-335 when compared to healthy donors. In vitro data demonstrate that upon uptake of miR335-enriched EVs by GC cells, the expression of CDH11 and PLAUR is altered in a similar manner as these genes are regulated in GC cells transfected with miR-335. In vivo studies in mice shows, that after intravenous injection of these EVs labeled with DiR, EVs enriched in miR-335 show different distribution in time in several organs, including stomach, in comparison to control EVs. Summary/Conclusion: MiR-335 is present in EVs isolated from both plasma and GC cell culture supernatants. EVs enriched in miR-335 show functional properties after cell uptake and different biodistribution in mice.
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