An enhanced apoptosis and a reduced angiogenesis are associated with the inhibition of lung colonisation in animals fed an n -3 polyunsaturated fatty acid-rich diet injected with a highly metastatic murine melanoma line

Diet quality is associated with primary melanoma thickness

Background

Objective

Methods

Results

Conclusions

Effects of Dietary n-3 and n-6 Polyunsaturated Fatty Acids in Inflammation and Cancerogenesis

The dietary recommendation encourages reducing saturated fatty acids (SFA) in diet and replacing them with polyunsaturated fatty acids (PUFAs) n-3 (omega-3) and n-6 (omega-6) to decrease the risk of metabolic disturbances. Consequently, excessive n-6 PUFAs content and high n-6/n-3 ratio are found in Western-type diet. The importance of a dietary n-6/n-3 ratio to prevent chronic diseases is linked with anti-inflammatory functions of linolenic acid (ALA, 18:3n-3) and longer-chain n-3 PUFAs. Thus, this review provides an overview of the role of oxylipins derived from n-3 PUFAs and oxylipins formed from n-6 PUFAs on inflammation. Evidence of PUFAs' role in carcinogenesis was also discussed. In vitro studies, animal cancer models and epidemiological studies demonstrate that these two PUFA groups have different effects on the cell growth, proliferation and progression of neoplastic lesions.

An omega-3 polyunsaturated fatty acid derivative, 18-HEPE, protects against CXCR4-associated melanoma metastasis

Melanoma has a high propensity to metastasize and exhibits a poor response to classical therapies. Dysregulation of the chemokine receptor gene CXCR4 is associated with melanoma progression, and although n-3 polyunsaturated fatty acids (PUFAs) are known to be beneficial for melanoma prevention, the underlying mechanism of this effect is unclear. Here, we used the n-3 fatty acid desaturase (Fat-1) transgenic mouse model of endogenous n-3 PUFA synthesis to investigate the influence of elevated n-3 PUFA levels in a mouse model of metastatic melanoma. We found that relative to wild-type (WT) mice, Fat-1 mice exhibited fewer pulmonary metastatic colonies and improved inflammatory indices, including reduced serum tumor necrosis factor alpha (TNF-α) levels and pulmonary myeloperoxidase activity. Differential PUFA metabolites in serum were considered a key factor to alter cancer cell travelling to lung, and we found that n-6 PUFAs such as arachidonic acid induced CXCR4 protein expression although n-3 PUFAs such as eicosapentaenoic acid (EPA) decreased CXCR4 levels. In addition, serum levels of the bioactive EPA metabolite, 18-HEPE, were elevated in Fat-1 mice relative to WT mice, and 18-HEPE suppressed CXCR4 expression in B16-F0 cells. Moreover, relative to controls, numbers of pulmonary metastatic colonies were reduced in WT mice receiving intravenous injections either of 18-HEPE or 18-HEPE-pretreated melanoma cells. Our results indicate that 18-HEPE is a potential anticancer metabolite that mediates, at least in part, the preventive effect of n-3 PUFA on melanoma metastasis.

Algal oil rich in n-3 polyunsaturated fatty acids suppresses B16F10 melanoma lung metastasis by autophagy induction

Melanoma is a malignant tumor that arises from epidermal melanocytes with high morbidity and mortality, and currently, there are no effective conventional genotoxic treatments or systematic treatment.

Role of β-catenin signaling in the anti-invasive effect of the omega-3 fatty acid DHA in human melanoma cells

BACKGROUND

We previously found that docosahexaenoic acid (DHA), a dietary polyunsaturated fatty acid present at high level in fatty fish, inhibited cell growth and induced differentiation of melanoma cells in vitro by increasing nuclear β-catenin content. An anti-neoplastic role of nuclear β-catenin was suggested in melanoma, and related to the presence in the melanocyte lineage of the microphtalmia transcription factor (MITF), which interferes with the transcription of β-catenin/TCF/LEF pro-invasive target genes.

OBJECTIVE

In the present work we investigated if DHA could inhibit the invasive potential of melanoma cells, and if this effect could be related to DHA-induced alterations of the Wnt/β-catenin signaling, including changes in MITF expression.

METHODS

WM115 and WM266-4 human melanoma, and B16-F10 murine melanoma cell lines were used. Cell invasion was evaluated by Wound Healing and Matrigel transwell assays. Protein expression was analyzed by Western Blotting and β-catenin phosphorylation by immunoprecipitation. The role of MITF in the anti-invasive effect of DHA was analyzed by siRNA gene silencing.

RESULTS

We found that DHA inhibited anchorage-independent cell growth, reduced their migration/invasion in vitro and down-regulated several Matrix Metalloproteinases (MMP: MMP-2, MT1-MMP and MMP-13), known to be involved in melanoma invasion. We related these effects to the β-catenin increased nuclear expression and PKA-dependent phosphorylation, as well as to the increased expression of MITF.

CONCLUSION

The data obtained further support the potential role of dietary DHA as suppressor of melanoma progression to invasive malignancy through its ability to enhance MITF expression and PKA-dependent nuclear β-catenin phosphorylation.

Diet in dermatology: Part II. Melanoma, chronic urticaria, and psoriasis

The roles of dietary factors in aggravating, preventing, or treating skin diseases are common questions encountered in dermatology practice. Part II of this two-part series reviews dietary modifications that can potentially be utilized in the management of melanoma, chronic urticaria, and psoriasis patients. Specifically, we examine the effect of alcohol consumption and supplementation with vitamins D and E, polyunsaturated fatty acids, selenium, green tea, resveratrol, and lycopene on melanoma risk. The relationships between chronic urticaria symptoms and dietary pseudoallergens, gluten, and vitamin D are analyzed. We explore weight loss, reduced alcohol consumption, and gluten avoidance as means of reducing psoriasis-associated morbidity, as well as the possible utility of supplementation with polyunsaturated fatty acids, folic acid, vitamin D, and antioxidants. With proper knowledge of the role of diet in these cutaneous disease processes, dermatologists can better answer patient inquiries and consider implementation of dietary modifications as adjuncts to other treatments and preventative measures.

Potential of long-chain n-3 polyunsaturated fatty acids in melanoma prevention

The possible antineoplastic activity of dietary long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs) has been supported by ample preclinical studies that have identified a number of molecular factors and pathways affected by these fatty acids and involved in cell growth, apoptosis, invasion, and angiogenesis. The aim of this critical review is to assess the current state of knowledge on the potential anticancer effects of LC n-3 PUFAs against malignant melanoma, one of the most common cancers among Western populations. The results of preclinical as well as human observational and interventional studies investigating the effects of LC n-3 PUFAs in melanoma were examined. Overall, the analysis of the literature reveals that, even though a large body of information is available, further effort is needed to identify the main molecular targets of LC n-3 PUFAs in melanoma. Moreover, additional well-designed human observational studies are essential to shed further light on the issue. The results of these studies could provide support and specific information for the development of clinical studies, especially those performed in combination with conventional or innovative antineoplastic therapies.

Docosahexaenoic acid, G protein-coupled receptors, and melanoma: is G protein-coupled receptor 40 a potential therapeutic target?

BACKGROUND

To determine the effect of docosahexaenoic acid (DHA) on the growth of human melanoma in vitro and in vivo and to better understand the potential role of the G protein-coupled receptors (GPRs) in mediating this effect.

MATERIALS AND METHODS

For in vitro studies, human melanoma and control fibroblast cells were treated with DHA and TAK-875 (selective GPR40 agonist) and a cell viability assay was performed to determine cell counts. A murine subcutaneous xenograft model of human melanoma was used to test the effect of dietary treatment with an omega-3 fatty acid (FA) rich diet compared with an omega-6 FA rich diet on the growth of human melanoma in vivo. A similar animal model was used to test the effect of oral TAK-875 on the growth of established melanoma tumors in vivo.

RESULTS

DHA has an inhibitory effect on the growth of human melanoma both in vitro and in vivo. Tumors from animals on the omega-3 FA rich diet were 69% smaller in weight (P = 0.005) and 76% smaller in volume compared with tumors from animals on the omega-6 FA rich diet. TAK-875 has an inhibitory effect on the growth of human melanoma both in vitro and in vivo. Tumors from animals treated with TAK-875 were 46% smaller in weight (P = 0.07), 62% smaller in volume (P = 0.03), and grew 77% slower (P = 0.04) compared with the placebo group.

CONCLUSIONS

DHA and TAK-875 have a profound and selective inhibitory effect on the growth of human melanoma both in vitro and in vivo.

ω-3 polyunsaturated fatty acids inhibit the proliferation of the lung adenocarcinoma cell line A549 in vitro

ω-3 polyunsaturated fatty acids (n-3 PUFA), in particular the marine-derived forms eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been demonstrated to affect cancer cell replication, the cell cycle and cell death. Epidemiological studies have also suggested diets rich in n-3 PUFA were inversely correlated with the development of cancer. In the present study, we explored the effects of DHA and EPA on the proliferation activity and apoptosis of the human lung adenocarcinoma cell line A549. A methyl thiazolyl tetrazolium (MTT) assay was used to detect cell proliferation, apoptosis was detected by flow cytometry and morphological analysis was determined by fluorescence microscopy and transmission electron microscopy. A549 cells were treated with different doses of DHA (40, 45, 50 and 55 µg/ml) or EPA (45, 50, 55 and 60 µg/ml) for 24, 48 and 72 h. The results demonstrated that DHA and EPA significantly suppressed the proliferation of A549 cells and induced apoptosis of A549 cells in a dose- and time-dependent manner. The apoptotic phenomenon was also confirmed by fluorescence microscopy and transmission electron microscopy. Furthermore, compared with the control, the formation of autophagosomes was clearly enhanced in DHA‑ or EPA-treated cells. In conclusion, DHA and EPA inhibited the proliferation of A549 cells and induced cell apoptosis and autophagy, which may provide new safe and effective options for the treatment of lung cancer in the future.

Omega-3 fatty acids and cancers: a systematic update review of epidemiological studies

Experimental models showed consistently a modulation of carcinogenesis by omega 3 polyunsaturated fatty acids (ω3 PUFA). Fish intake is often described as part of a beneficial dietary pattern. However, observational epidemiological studies on the relationship between ω3 PUFA reported conflicting results. The objective of this systematic review is to determine whether there exists any progress in the evaluation of the causal relationship between dietary ω3 PUFA and cancers since the previous FAO/OMS expert consultation and whether it is possible to propose preventive and/or adjuvant therapeutic recommendations. Prospective and case-control observational studies published since 2007 and meeting validity criteria were considered together with RCT. Experimental studies are mentioned to provide for biological plausibility. When evaluating the level of evidence, a portfolio approach was used, weighted by a hierarchy giving higher importance to prospective studies followed by RCT if any. There is a probable level of evidence that ALA per se is neither a risk factor nor a beneficial factor with regards to cancers. Observational studies on colorectal, prostate and breast cancers only provided limited evidence suggesting a possible role of LC-ω3PUFA in cancer prevention because insufficient homogeneity of the observations. Explanation for heterogeneity might be the inherent difficulties associated with epidemiology (confounding and dietary pattern context, measurement error, level of intake, genetic polymorphism). The role of LC-ω3PUFA as adjuvant, might be considered of possible use, in view of the latest RCT on lung cancers even if RCT on other cancers still need to be undertaken.

22 : 6n-3 DHA inhibits differentiation of prostate fibroblasts into myofibroblasts and tumorigenesis

Prostate cancer is one of the most common malignancies in men. Epidemiological and experimental studies have revealed that stromal cells of the tumour microenvironment contribute to the development of prostate cancers, while long-chain n-3 PUFA-enriched diets reduce the risk of this tumour histotype. These findings prompted us to investigate whether DHA, an n-3 PUFA, may abrogate differentiation of prostate fibroblasts into myofibroblasts, the activated form of fibroblasts generally involved in prostate cancer progression. We used the human prostate carcinoma cell line (PC3) as a prostate adenocarcinoma model and found that DHA (1) inhibits α-smooth muscle actin (α-SMA) expression, a typical marker of myofibroblast differentiation, in prostate fibroblasts stimulated in vitro with transforming growth factor-β (TGF-β), (2) blocks the matrix metalloproteinase-2-dependent enhanced invasiveness of PC3 prostate adenocarcinoma cells migrated in a medium conditioned by TGF-β-stimulated prostate fibroblasts, (3) prevents epithelial-mesenchymal transition (EMT) and invasiveness of PC3 cells promoted by a medium conditioned by TGF-β-stimulated prostate fibroblasts, and (4) reduces the growth rate of tumours obtained in immunodeficient animals injected with PC3 cells plus TGF-β-stimulated prostate fibroblasts. Moreover, DHA was found to revert α-SMA expression and the invasiveness-promoting activity exerted in PC3 cells by tumoral-activated fibroblasts. Thus, DHA represents a suitable agent to inhibit prostate myofibroblast differentiation, invasiveness and EMT, two most important tumour-promoting activities involved in the progression of prostate cancer cells.

Current research and development of chemotherapeutic agents for melanoma

Cutaneous malignant melanoma is the most lethal form of skin cancer and an increasingly common disease worldwide. It remains one of the most treatment-refractory malignancies. The current treatment options for patients with metastatic melanoma are limited and in most cases non-curative. This review focuses on conventional chemotherapeutic drugs for melanoma treatment, by a single or combinational agent approach, but also summarizes some potential novel phytoagents discovered from dietary vegetables or traditional herbal medicines as alternative options or future medicine for melanoma prevention. We explore the mode of actions of these natural phytoagents against metastatic melanoma.

Dietary n-3 polyunsaturated fatty acids enhance metastatic dissemination of murine T lymphoma cells

Epidemiological investigation and animal studies have shown that dietary n-3 PUFA prevent the development and progression of certain types of cancer. However, conflicting results have been reported by the few studies that focused on the effect of dietary n-3 PUFA on the development of metastases. In the present study, we investigated the metastatic dissemination of murine T lymphoma lines with different metastatic potential transplanted into mice fed a fish oil diet, compared with mice fed a maize oil diet. Transplantation of highly metastatic S11 cells into animals fed a fish oil diet induced a large lymphomatoid infiltration in the spleen, associated with an eight-fold increase in spleen weight, compared with normal animals on the same diet. In contrast, only a limited increase in spleen weight was found in animals transplanted with S11 cells while fed a maize oil diet. No significant increase in spleen weight was found in animals transplanted with low-metastatic 164T2 cells regardless of whether they were fed a fish oil or a maize oil diet. At the end of experiment, an overt cachexia was shown by animals fed a fish oil diet transplanted with S11 cells, but not by those transplanted with 164T2 cells. The particularly high pro-metastatic effect of dietary n-3 PUFA on S11 cells rules out the generalisation that dietary n-3 PUFA inhibit tumour growth and progression.