Oleic acid promotes MMP-9 secretion and invasion in breast cancer cells

Obesity-associated Breast Cancer: Analysis of risk factors

Several studies show that a significantly stronger association is obvious between increased body mass index (BMI) and higher breast cancer incidence. Furthermore, obese women are at higher risk of all-cause and breast cancer specific mortality when compared to non-obese women with breast cancer. In this context, increased levels of estrogens due to excessive aromatization activity of the adipose tissue, overexpression of pro-inflammatory cytokines, insulin resistance, hyperactivation of insulin-like growth factors (IGFs) pathways, adipocyte-derived adipokines, hypercholesterolemia and excessive oxidative stress contribute to the development of breast cancer in obese women. While higher breast cancer risk with hormone replacement therapy is particularly evident among lean women, in postmenopausal women who are not taking exogenous hormones, general obesity is a significant predictor for breast cancer. Moreover, increased plasma cholesterol leads to accelerated tumor formation and exacerbates their aggressiveness. In contrast to postmenopausal women, premenopausal women with high BMI are inversely associated with breast cancer risk. Nevertheless, life-style of women for breast cancer risk is regulated by avoiding the overweight and a high-fat diet. Estrogen-plus-progestin hormone therapy users for more than 5 years have elevated risks of both invasive ductal and lobular breast cancer. Additionally, these cases are more commonly node-positive and have a higher cancer-related mortality. Collectively, in this chapter, the impacts of obesity-related estrogen, cholesterol, saturated fatty acid, leptin and adiponectin concentrations, aromatase activity, leptin and insulin resistance on breast cancer patients are evaluated. Obesity-related prognostic factors of breast cancer also are discussed at molecular basis.

Obesity and Breast Cancer: Current Insights on the Role of Fatty Acids and Lipid Metabolism in Promoting Breast Cancer Growth and Progression

Obesity and excess accumulation of adipose tissue are known risk factors for several types of cancer, including breast cancer. With the incidence of obesity constantly rising worldwide, understanding the molecular details of the interaction between adipose tissue and breast tumors, the most common tumors in women, becomes an urgent task. In terms of lipid metabolism, most of the studies conducted so far focused on upregulated de novo lipid synthesis in cancer cells. More recently, the use of extracellular lipids as source of energy came into focus. Especially in obesity, associated dysfunctional adipose tissue releases increased amounts of fatty acids, but also dietary lipids can be involved in promoting tumor growth and progression. In addition, it was shown that breast cancer cells and adipocytes, which are a major component of the stroma of breast tumors, are able to directly interact with each other. Breast cancer cells and adjacent adipocytes exchange molecules such as growth factors, chemokines, and interleukins in a reciprocal manner. Moreover, it was shown that breast cancer cells can access and utilize fatty acids produced by neighboring adipocytes. Thus adipocytes, and especially hypertrophic adipocytes, can act as providers of lipids, which can be used as a source of energy for fatty acid oxidation and as building blocks for tumor cell growth.

Omental adipocytes enhance the invasiveness of gastric cancer cells by oleic acid-induced activation of the PI3K-Akt signaling pathway

A considerable number of patients with advanced gastric cancer have a clear predilection for metastasis to the great omentum, an organ mainly composed of adipose tissue. However, it remains unclear why tumor cells preferentially spread to and progress in the omentum. Here, we used a two-dimensional co-culture system to simulate the crosstalk between adipocytes and gastric cancer cells and showed that after co-culture with isolated omental adipocytes, gastric cancer cells exhibited a significant increase in lipid uptake and enhanced invasiveness. A lipidomic study showed that gastric cancer cells accumulated higher levels of oleic acid during the co-culture. By performing an assay of key enzymes in lipid synthesis, we demonstrated that the increased amount of oleic acid in gastric cancer cells mainly came from the adjacent adipocytes in the co-culture system. Furthermore, our data showed that at a certain concentration range, oleic acid treatment enhanced the invasiveness of gastric cancer cells in vitro and in a CAM assay, through the PI3K/Akt pathway, with the associated increased expression of the key pro-invasion factor MMP-2. Taken together, our results demonstrated that adipocytes may serve as an exogenous source of oleic acid that promotes gastric cancer cell invasion through the PI3K/Akt signaling pathway.

Oleic acid-induced ANGPTL4 enhances head and neck squamous cell carcinoma anoikis resistance and metastasis via up-regulation of fibronectin

Obese patients have higher levels of free fatty acids (FFAs) in their plasma and a higher risk of cancer than their non-obese counterparts. However, the mechanisms involved in the regulation of cancer metastasis by FFAs remain unclear. In this study, we found that oleic acid (OA) induced angiopoietin-like 4 (ANGPTL4) protein expression and secretion and conferred anoikis resistance to head and neck squamous cell carcinomas (HNSCCs). The autocrine production of OA-induced ANGPTL4 further promoted HNSCC migration and invasion. In addition, the expression of peroxisome proliferator-activated receptor (PPAR) was essential for the OA-induced ANGPTL4 expression and invasion. The levels of OA-induced epithelial-mesenchymal transition markers, such as vimentin, MMP-9, and fibronectin and its downstream effectors Rac1/Cdc42, were significantly reduced in ANGPTL4-depleted cells. Knocking down fibronectin inhibited the expression of MMP-9 and repressed OA- and recombinant ANGPTL4-induced HNSCC invasion. On the other hand, ANGPTL4 siRNA inhibited OA-induced MMP-9 expression, which was reversed in fibronectin-overexpressing cells. Furthermore, the depletion of ANGPTL4 impeded the OA-primed metastatic seeding of tumor cells in the lungs. These results demonstrate that OA enhances HNSCC metastasis through the ANGPTL4/fibronectin/Rac1/Cdc42 and ANGPTL4/fibronectin/MMP-9 signaling axes.

Different Biological Action of Oleic Acid in ALDHhigh and ALDHlow Subpopulations Separated from Ductal Carcinoma In Situ of Breast Cancer

The mechanisms underlying breast cancer progression of ductal carcinoma in situ (DCIS) associated with fatty acids are largely unknown. In the present study, we compared the action of oleic acid (OA) on two human DCIS cell lines, MCF10DCIS.COM (ER/PR/HER2-negative) and SUM225 (HER2 overexpressed). OA led to a significant increase in proliferation, migration, lipid accumulation and the expression of lipogenic proteins, such as SREBP-1, FAS and ACC-1, in MCF10DCIS.COM cells but not SUM225 cells. The ALDH^high subpopulation analyzed by the ALDEFLUOR assay was approximately 39.2±5.3% of MCF10DCIS.COM cells but was small (3.11±0.9%) in SUM225 cells. We further investigated the different biological action of OA in the distinct ALDH^low and ALDH^high subpopulations of MCF10DCIS.COM cells. OA led to an increase in the expression of ALDH1A1, ALDH1A2 and ALDH1A3 in MCF10DCIS.COM cells. SREBP-1 and ACC-1 were highly expressed in ALDH^high cells relative to ALDH^low cells, whereas FAS was higher in ALDH^low cells. In the presence of OA, ALDH^high cells were more likely to proliferate and migrate and displayed significantly high levels of SREBP-1 and FAS and strong phosphorylation of FAK and AKT relative to ALDH^low cells. This study suggests that OA could be a critical risk factor to promote the proliferation and migration of ALDH^high cells in DCIS, leading to breast cancer progression.

Anacardic Acid, Salicylic Acid, and Oleic Acid Differentially Alter Cellular Bioenergetic Function in Breast Cancer Cells

Anacardic acid is a dietary and medicinal phytochemical that inhibits breast cancer cell proliferation and uncouples oxidative phosphorylation (OXPHOS) in isolated rat liver mitochondria. Since mitochondrial-targeted anticancer therapy (mitocans) may be useful in breast cancer, we examined the effect of anacardic acid on cellular bioenergetics and OXPHOS pathway proteins in breast cancer cells modeling progression to endocrine-independence: MCF-7 estrogen receptor α (ERα)+ endocrine-sensitive; LCC9 and LY2 ERα+, endocrine-resistant, and MDA-MB-231 triple negative breast cancer (TNBC) cells. At concentrations similar to cell proliferation IC50 s, anacardic acid reduced ATP-linked oxygen consumption rate (OCR), mitochondrial reserve capacity, and coupling efficiency while increasing proton leak, reflecting mitochondrial toxicity which was greater in MCF-7 compared to endocrine-resistant and TNBC cells. These results suggest tolerance in endocrine-resistant and TNBC cells to mitochondrial stress induced by anacardic acid. Since anacardic acid is an alkylated 2-hydroxybenzoic acid, the effects of salicylic acid (SA, 2-hydroxybenzoic acid moiety) and oleic acid (OA, monounsaturated alkyl moiety) were tested. SA inhibited whereas OA stimulated cell viability. In contrast to stimulation of basal OCR by anacardic acid (uncoupling effect), neither SA nor OA altered basal OCR- except OA inhibited basal and ATP-linked OCR, and increased ECAR, in MDA-MB-231 cells. Changes in OXPHOS proteins correlated with changes in OCR. Overall, neither the 2-hydroxybenzoic acid moiety nor the monounsaturated alky moiety of anacardic acid is solely responsible for the observed mitochondria-targeted anticancer activity in breast cancer cells and hence both moieties are required in the same molecule for the observed effects. J. Cell. Biochem. 117: 2521-2532, 2016. © 2016 Wiley Periodicals, Inc.

Biological and Nutritional Properties of Palm Oil and Palmitic Acid: Effects on Health

A growing body of evidence highlights the close association between nutrition and human health. Fat is an essential macronutrient, and vegetable oils, such as palm oil, are widely used in the food industry and highly represented in the human diet. Palmitic acid, a saturated fatty acid, is the principal constituent of refined palm oil. In the last few decades, controversial studies have reported potential unhealthy effects of palm oil due to the high palmitic acid content. In this review we provide a concise and comprehensive update on the functional role of palm oil and palmitic acid in the development of obesity, type 2 diabetes mellitus, cardiovascular diseases and cancer. The atherogenic potential of palmitic acid and its stereospecific position in triacylglycerols are also discussed.

Oncologic photodynamic diagnosis and therapy: confocal Raman/fluorescence imaging of metal phthalocyanines in human breast cancer tissue in vitro

Raman microspectroscopy and confocal Raman imaging combined with confocal fluorescence were used to study the distribution and aggregation of aluminum tetrasulfonated phthalocyanine (AlPcS4) in noncancerous and cancerous breast tissues. The results demonstrate the ability of Raman spectroscopy to distinguish between noncancerous and cancerous human breast tissue and to identify differences in the distribution and aggregation of aluminum phthalocyanine, which is a potential photosensitizer in photodynamic therapy (PDT), photodynamic diagnosis (PDD) and photoimmunotherapy (PIT) of cancer. We have observed that the distribution of aluminum tetrasulfonated phthalocyanine confined in cancerous tissue is markedly different from that in noncancerous tissue. We have concluded that Raman imaging can be treated as a new and powerful technique useful in cancer photodynamic therapy, increasing our understanding of the mechanisms and efficiency of photosensitizers by better monitoring localization in cancer cells as well as the clinical assessment of the therapeutic effects of PDT and PIT.

Intratumor cholesteryl ester accumulation is associated with human breast cancer proliferation and aggressive potential: a molecular and clinicopathological study

BACKGROUND

The metabolic effect of intratumor cholesteryl ester (CE) in breast cancer remains poorly understood. The objective was to analyze the relationship between intratumor CE content and clinicopathological variables in human breast carcinomas.

METHODS

We classified 30 breast carcinoma samples into three subgroups: 10 luminal-A tumors (ER+/PR+/Her2-), 10 Her-2 tumors (ER-/PR-/Her2+), and 10 triple negative (TN) tumors (ER-/PR-/Her2-). We analyzed intratumor neutral CE, free cholesterol (FC) and triglyceride (TG) content by thin layer chromatography after lipid extraction. RNA and protein levels of lipid metabolism and invasion mediators were analyzed by real time PCR and Western blot analysis.

RESULTS

Group-wise comparisons, linear regression and logistic regression models showed a close association between CE-rich tumors and higher histologic grade, Ki-67 and tumor necrosis. CE-rich tumors displayed higher mRNA and protein levels of low-density lipoprotein receptor (LDLR) and scavenger receptor class B member 1 (SCARB1). An increased expression of acetyl-Coenzyme A acetyltransferase 1 (ACAT1) in CE-rich tumors was also reported.

CONCLUSIONS

Intratumor CE accumulation is intimately linked to proliferation and aggressive potential of breast cancer tumors. Our data support the link between intratumor CE content and poor clinical outcome and open the door to new antitumor interventions.

Cloning, identification and functional characterization of bovine free fatty acid receptor-1 (FFAR1/GPR40) in neutrophils

Long chain fatty acids (LCFAs), which are ligands for the G-protein coupled receptor FFAR1 (GPR40), are increased in cow plasma after parturition, a period in which they are highly susceptible to infectious diseases. This study identified and analyzed the functional role of the FFAR1 receptor in bovine neutrophils, the first line of host defense against infectious agents. We cloned the putative FFAR1 receptor from bovine neutrophils and analyzed the sequence to construct a homology model. Our results revealed that the sequence of bovine FFAR1 shares 84% identity with human FFAR1 and 31% with human FFAR3/GPR41. Therefore, we constructed a homology model of bovine FFAR1 using human as the template. Expression of the bovine FFAR1 receptor in Chinese hamster ovary (CHO)-K1 cells increased the levels of intracellular calcium induced by the LCFAs, oleic acid (OA) and linoleic acid (LA); no increase in calcium mobilization was observed in the presence of the short chain fatty acid propionic acid. Additionally, the synthetic agonist GW9508 increased intracellular calcium in CHO-K1/bFFAR1 cells. OA and LA increased intracellular calcium in bovine neutrophils. Furthermore, GW1100 (antagonist of FFAR1) and U73122 (phospholipase C (PLC) inhibitor) reduced FFAR1 ligand-induced intracellular calcium in CHO-K1/bFFAR1 cells and neutrophils. Additionally, inhibition of FFAR1, PLC and PKC reduced the FFAR1 ligand-induced release of matrix metalloproteinase (MMP)-9 granules and reactive oxygen species (ROS) production. Thus, we identified the bovine FFAR1 receptor and demonstrate a functional role for this receptor in neutrophils activated with oleic or linoleic acid.

Application of desorption electrospray ionization mass spectrometry imaging in breast cancer margin analysis

Distinguishing tumor from normal glandular breast tissue is an important step in breast-conserving surgery. Because this distinction can be challenging in the operative setting, up to 40% of patients require an additional operation when traditional approaches are used. Here, we present a proof-of-concept study to determine the feasibility of using desorption electrospray ionization mass spectrometry imaging (DESI-MSI) for identifying and differentiating tumor from normal breast tissue. We show that tumor margins can be identified using the spatial distributions and varying intensities of different lipids. Several fatty acids, including oleic acid, were more abundant in the cancerous tissue than in normal tissues. The cancer margins delineated by the molecular images from DESI-MSI were consistent with those margins obtained from histological staining. Our findings prove the feasibility of classifying cancerous and normal breast tissues using ambient ionization MSI. The results suggest that an MS-based method could be developed for the rapid intraoperative detection of residual cancer tissue during breast-conserving surgery.

Arachidonic acid promotes migration and invasion through a PI3K/Akt-dependent pathway in MDA-MB-231 breast cancer cells

Arachidonic acid (AA) is a common dietary n-6 cis polyunsaturated fatty acid that under physiological conditions is present in an esterified form in cell membrane phospholipids, however it might be present in the extracellular microenvironment. AA and its metabolites mediate FAK activation, adhesion and migration in MDA-MB-231 breast cancer cells. However, it remains to be investigated whether AA promotes invasion and the signal transduction pathways involved in migration and invasion. Here, we demonstrate that AA induces Akt2 activation and invasion in MDA-MB-231 cells. Akt2 activation requires the activity of Src, EGFR, and PIK3, whereas migration and invasion require Akt, PI3K, EGFR and metalloproteinases activity. Moreover, AA also induces NFκB-DNA binding activity through a PI3K and Akt-dependent pathway. Our findings demonstrate, for the first time, that Akt/PI3K and EGFR pathways mediate migration and invasion induced by AA in MDA-MB-231 breast cancer cells.

Plasma metabolomic profiles in breast cancer patients and healthy controls: by race and tumor receptor subtypes

BACKGROUND

A few studies in the last several years have shown that metabolomics, the study of metabolites and small intermediate molecules, may help better understand the breast carcinogenesis. However, breast cancer is a heterogeneous disease with different subtypes. Additionally, there is a significant racial difference in terms of breast cancer incidence and mortality. Few, if any, metabolomics studies in breast cancer have considered race and tumor subtypes in the study design.

METHODS

We performed a global metabolomic profiling using mass spectrometry and samples from 60 breast cancer cases and 60 matched controls.

RESULTS

A total of 375 named metabolites were observed, with 117 metabolites whose levels were significantly different between African American and Caucasian American women (P < .05 and q < 0.10) and 78 that differed between breast cancer cases and healthy controls (P < .05 and q < 0.10). Most of those differentiated metabolites belong to amino acids, fatty acids, and lysolipids. In the pathway-based analysis, we found that plasma levels of many amino acids were statistically significantly lower in patients with breast cancer, especially those with triple-negative breast cancer, than healthy controls. However, plasma levels of many FAs related to β-oxidation were statistically significantly higher in patients with breast cancer than healthy controls, suggesting the possibility of altered FA β-oxidation in patients with breast cancer.

CONCLUSIONS

Because of small sample size, the clinical usage of the metabolites from this study is unclear. Further validation of those significant metabolites is warranted, especially with the consideration of racial difference.

Trophoblast invasion and blood vessel remodeling are altered in a rat model of lifelong maternal obesity

Maternal obesity is associated with an increased risk of a number of pregnancy complications, including fetal demise, which may be linked to impaired placental development as a result of altered trophoblast invasion and vessel remodeling. Therefore, we examined these parameters in pregnant rats fed a control (normal weight) or high fat (HF) diet (obese) at 2 critical times of rat placental development. Early trophoblast invasion was increased by approximately 2-fold in HF-fed dams with a concomitant increase in the expression of matrix metalloproteinase 9 protein, a mediator of tissue remodeling and invasion. Furthermore, we observed significantly higher levels of smooth muscle actin surrounding the placental spiral arteries of HF-fed dams, suggesting impaired spiral artery remodeling. Taken together, the results of this study suggest that altered placental development is an important contributor to the poor pregnancy outcomes and increased fetal demise in our model of lifelong maternal obesity.

CCL20 induces migration and proliferation on breast epithelial cells

The communication between the tumor cells and the surrounding cells helps drive the process of tumor progression. Since the microenvironment of breast cancer includes CCL20 chemokine, the purpose of this study was to determine whether CCL20 modulates the physiology of healthy breast epithelial cells in areas adjacent to the tumor. Therefore, primary cultures of mammary cells taken from normal peritumoral areas were used. We assessed that breast cells expressed CCR6 CCL20 receptor. Using molecular (siRNA) and pharmacological (inhibitors) techniques, we found multiple signaling kinases to be activated by CCR6 and involved in CCL20-induced breast cell proliferation and migration. The binding of 10 ng/ml CCL20 to CCR6 induced cell migration whilst higher concentrations (from 15 to 25 ng/ml) led to cell proliferation. CCL20 controlled cell migration and MMP-9 expression by PKC-alpha that activated Src, which caused the activation of downstream Akt, JNK, and NF-kB pathways. Furthermore, higher CCL20 concentrations increased cycE and decreased p27Kip expression ending in enhanced cell proliferation. Cell proliferation occurred through PKC-epsilon activation that transactivated EGFR and ERK1/2/MAPK pathway. Although activated by different CCL20 concentrations, these pathways function in parallel and crosstalk to some extent, inasmuch as Akt activation was responsible for ERK1/2 nuclear translocation and enhanced the transcription of of c-fos and c-myc, involved in cell proliferation. In summary, tumor cells exchange signals with the surrounding healthy cells modifying the extracellular matrix through enzyme secretion; thus, CCL20 might be a factor involved in the ontogeny of breast carcinoma.

Extracellular lipid metabolism influences the survival of ovarian cancer cells

Lysophosphatidic acid (LPA) is an extracellular lipid mediator consisting of a fatty acid and a phosphate group linked to the glycerol backbone. Here, we show that 1-oleoyl- and 1-palmitoyl-LPA, but not 1-stearoyl- or alkyl-LPA, enhance HNOA ovarian cancer cell survival. Other lysophospholipids with oleic or lauric acid, but not stearic acid, also induce the survival effects. HNOA cells have the lipase activities that cleave LPA to generate fatty acid. Oleic acid stimulates HNOA cell survival via increased glucose utilization. Our findings suggest that extracellular lysolipid metabolism might play an important role in HNOA cell growth.

Role of arachidonic acid metabolism in Stat5 activation induced by oleic acid in MDA-MB-231 breast cancer cells

Epidemiological studies and animal models suggest an association between high levels of dietary fat intake and an increased risk of breast cancer. In breast cancer cells, the free fatty acid oleic acid (OLA) induces proliferation, migration, invasion and an increase of MMP-9 secretion. However, the role of OLA on Stat5 activation and the participation of COX-2 and LOXs activity in Stat5 activation induced by OLA remain to be investigated. We demonstrate here that stimulation of MDA-MB-231 breast cancer cells with 100 μM OLA induces Stat5 phosphorylation at Tyr-694 and an increase of Stat5-DNA complex formation. The Stat5 DNA-binding activity requires COX-2, LOXs, metalloproteinases and Src activities. In addition, OLA induces cell migration through a Stat5-dependent pathway. In summary, our findings establish that OLA induces cell migration through a Stat5-dependent pathway and that Stat5 activation requires AA metabolites in MDA-MB-231 breast cancer cells.

Action of hexachlorobenzene on tumor growth and metastasis in different experimental models

Hexachlorobenzene (HCB) is a widespread organochlorine pesticide, considered a possible human carcinogen. It is a dioxin-like compound and a weak ligand of the aryl hydrocarbon receptor (AhR). We have found that HCB activates c-Src/HER1/STAT5b and HER1/ERK1/2 signaling pathways and cell migration, in an AhR-dependent manner in MDA-MB-231 breast cancer cells. The aim of this study was to investigate in vitro the effect of HCB (0.005, 0.05, 0.5, 5μM) on cell invasion and metalloproteases (MMPs) 2 and 9 activation in MDA-MB-231 cells. Furthermore, we examined in vivo the effect of HCB (0.3, 3, 30mg/kg b.w.) on tumor growth, MMP2 and MMP9 expression, and metastasis using MDA-MB-231 xenografts and two syngeneic mouse breast cancer models (spontaneous metastasis using C4-HI and lung experimental metastasis using LM3). Our results show that HCB (5μM) enhances MMP2 expression, as well as cell invasion, through AhR, c-Src/HER1 pathway and MMPs. Moreover, HCB increases MMP9 expression, secretion and activity through a HER1 and AhR-dependent mechanism, in MDA-MB-231 cells. HCB (0.3 and 3mg/kg b.w.) enhances subcutaneous tumor growth in MDA-MB-231 and C4-HI in vivo models. In vivo, using MDA-MB-231 model, the pesticide (0.3, 3 and 30mg/kg b.w.) activated c-Src, HER1, STAT5b, and ERK1/2 signaling pathways and increased MMP2 and MMP9 protein levels. Furthermore, we observed that HCB stimulated lung metastasis regardless the tumor hormone-receptor status. Our findings suggest that HCB may be a risk factor for human breast cancer progression.

Arachidonic acid induces an increase of β-1,4-galactosyltransferase I expression in MDA-MB-231 breast cancer cells

Arachidonic acid (AA) is a common dietary n-6 cis polyunsaturated fatty acid that under physiological conditions is present in an esterified form in cell membrane phospholipids, and it might be present in the extracellular microenvironment. AA and its metabolites are implicated in FAK activation and cell migration in MDA-MB-231 breast cancer cells, and an epithelial-to-mesenchymal-like transition process in mammary non-tumorigenic epithelial cells MCF10A. During malignant transformation is present an altered expression of glycosiltransferases, which promote changes on the glycosilation of cell-surface proteins. The β-1,4-galactosyltransferase I (GalT I) is an enzyme that participates in a variety of biological functions including cell growth, migration, and spreading. However, the participation of AA in the regulation of GalT I expression and the role of this enzyme in the cell adhesion process in breast cancer cells remains to be investigated. In the present study, we demonstrate that AA induces an increase of GalT I expression through a PLA2α, Src, ERK1/2, and LOXs activities-dependent pathway in MDA-MB-231 breast cancer cells. Moreover, MDA-MB-231 cells adhere to laminin via GalT I expression and pretreatment of cells with AA induces an increase of cell adhesion to laminin. In conclusion, our findings demonstrate, for the first time, that AA promotes an increase of GalT I expression through an AA metabolism, Src and ERK1/2 activities-dependent pathway, and that GalT I plays a pivotal role in cell adhesion to laminin in MDA-MB-231 breast cancer cells.

Effects of oleic acid on cell proliferation through an integrin-linked kinase signaling pathway in 786-O renal cell carcinoma cells

An increased risk of renal cell carcinoma (RCC) has been linked with obesity and metabolic syndrome. However, the mechanisms by which lipid metabolic disorders affect the development of RCC remain unclear and highly controversial. Integrin-linked kinase (ILK) is a serine/threonine protein kinase involved in the regulation of tumor cell growth and angiogenesis. In the present study, the effect of free fatty acids in the promotion of RCC progression was investigated by upregulating ILK. Results of the MTT assay indicated that treatment of 786-O cells with oleic acid induced a concentration-dependent increase in cell viability. Flow cytometry analysis revealed that the effect of oleic acid on cell apoptosis was not significant. Following treatment with oleic acid, the expression of ILK, phospho-Akt and G protein-coupled receptor 40 (GPR40) was increased in 786-O cells. These effects were reversed when the expression of ILK was downregulated using specific small interfering RNA. These results indicate that free fatty acids are associated with the development of renal cell carcinoma via activation of the GPR40/ILK/Akt pathway, revealing a novel mechanism for the correlation between metabolic disturbance and renal carcinoma.

Role of LOXs and COX-2 on FAK activation and cell migration induced by linoleic acid in MDA-MB-231 breast cancer cells

BACKGROUND

Epidemiological studies and animal models suggest a link between high levels of dietary fat intake and an increased risk of developing breast cancer. Particularly, free fatty acids (FFAs) are involved in several processes, including proliferation, migration and invasion, in breast cancer cells. Linoleic acid (LA) is a dietary n-6 polyunsaturated fatty acid that is known to induce proliferation and invasion in breast cancer cells. So far, however, the contribution of LA to focal adhesion kinase (FAK) activation and cell migration in breast cancer cells has not been studied.

RESULTS

Here, we show that LA promotes FAK and Src activation, as well as cell migration, in MDA-MB-231 breast cancer cells. FAK activation and cell migration require Src, Gi/Go, COX-2 and LOXs activities, whereas both are independent of Δ6 desaturase activity. In addition, we show that cell migration requires FAK activity, whereas FAK activation requires Src activity, thus suggesting a reciprocal catalytic activation mechanism of FAK and Src.

CONCLUSIONS

In summary, our findings show that LA induces FAK activation and cell migration in MDA-MB-231 breast cancer cells.

Dietary intake of specific fatty acids and breast cancer risk among postmenopausal women in the VITAL cohort

Studies of dietary fat intake and breast cancer have been inconsistent and few have examined specific fatty acids. We examined the association between specific monounsaturated (MUFA), polyunsaturated (PUFA), saturated (SFA), and trans-fatty acids (TFA) and breast cancer risk. Participants, 50-76 yr, were female members of the VITamins And Lifestyle (VITAL) Cohort, who were postmenopausal at baseline. In 2000-2002, participants completed a food frequency questionnaire. Seven hundred seventy-two incident, primary breast cancer cases were identified using a population-based cancer registry. Cox proportional hazard models estimated hazard ratios (HR) and 95% confidence intervals (95% CI) for the association between fatty acid intake and breast cancer risk. Intake of total MUFAs (highest vs. lowest quintile: HR = 1.61, 95% CI: 1.08-2.38, P trend = 0.02), particularly myristoleic and erucic acids, was associated with increased breast cancer risk. Whereas total SFA was suggestive of an increased risk (HR = 1.47, 95% CI: 1.00-2.15, P trend = 0.09), strong associations were observed for palmitic, margaric, and stearic acids. Total TFA and PUFA intake were not associated with breast cancer. However, among TFAs, linolelaidic acid was positively associated with risk; among PUFAs, intake of eicosapentaenoic and docosahexaenoic acids were inversely associated with risk. Our findings show that fatty acids are heterogeneous in their association with postmenopausal breast cancer risk.

Selection of a MCF-7 Breast Cancer Cell Subpopulation with High Sensitivity to IL-1β: Characterization of and Correlation between Morphological and Molecular Changes Leading to Increased Invasiveness

Cancer and inflammation are closely related in tumor malignancy prognosis. Breast cancer MCF-7 cells have a poor invasive phenotype, although, under IL-1β stimulus, acquire invasive features. Cell response heterogeneity has precluded precise evaluation of the malignant transition. MCF-7A3 cells were selected for high sensitivity to IL-1β stimulus, uniform expression of CXCR4, and stability of IL1-RI. Structural changes, colony formation ability, proliferation rate, chemotaxis, Matrigel invasion, E-cadherin mRNA expression and protein localization were determined in these cells and in MCF-7 parental cells under the stimulus of IL-1β. Selected MCF-7A3 cells showed a uniform response to IL-1β stimulation increasing features of invasive cells such as scattering, colony formation, proliferation, chemokinesis and invasion. Basal expression of E-cadherin mRNA was higher, and IL-1β stimulus had no further effect at early times of cytokine exposure. Total E-cadherin levels remained unchanged in parental cells, whereas levels decreased, as MCF-7A3 cells became fibroblastoid or scattered. Triton X-100 soluble/insoluble E-cadherin ratios were highly increased in these cells, while, in MCF-7pl cells, ratios could not be correlated with morphology changes. MCF-7A3 cells uniform response to IL-1β allowed characterization of changes induced by the cytokine that had not been assessed when using heterogeneous cell lines.

Basic aspects of tumor cell fatty acid-regulated signaling and transcription factors

This article reviews the current knowledge and experimental research about the mechanisms by which fatty acids and their derivatives control specific gene expression involved during carcinogenesis. Changes in dietary fatty acids, specifically the polyunsaturated fatty acids of the ω-3 and ω-6 families and some derived eicosanoids from lipoxygenases, cyclooxygenases, and cytochrome P-450, seem to control the activity of transcription factor families involved in cancer cell proliferation or cell death. Their regulation may be carried out either through direct binding to DNA as peroxisome proliferator-activated receptors or via modulation in an indirect manner of signaling pathway molecules (e.g., protein kinase C) and other transcription factors (nuclear factor kappa B and sterol regulatory element binding protein). Knowledge of the mechanisms by which fatty acids control specific gene expression may identify important risk factors for cancer and provide insight into the development of new therapeutic strategies for a better management of whole body lipid metabolism.

Suppression of human lung cancer cell proliferation and metastasis in vitro by the transducer of ErbB-2.1 (TOB1)

AIM

To investigate the effects of the transducer of ErbB-2.1 (TOB1) on the proliferation, migration and invasion of human lung cancer cells in vitro.

METHODS

Human lung cancer cell lines (95-D, A549, NCI-H1299, NCI-H1975, NCI-H661, NCI-H446, NCI-H1395, and Calu-3) and the normal human bronchial epithelial (HBE) cell line were tested. The expression levels of TOB1 in the cells were determined with Western blot and RT-PCR analyses. TOB1-overexpressing cell line 95-D/TOB1 was constructed using lipofectamine-induced TOB1 recombinant plasmid transfection and selective G418 cell culture. The A549 cells were transcend-transfected with TOB1-siRNA. MTT assay, flow cytometry and Western blot analysis were used to examine the effects of TOB1 on cancer cell proliferation and wound healing. Transwell invasive assay was performed to evaluate the effects of TOB1 on cancer cell migration and invasion. The activity of MMP2 and MMP9 was measured using gelatin zymography assay.

RESULTS

The expression levels of TOB1 in the 8 human lung cancer cell lines were significantly lower than that in HBE cells. TOB1 overexpression inhibited the proliferation of 95-D cells, whereas TOB1 knockdown with TOB1-siRNA promoted the growth of A549 cells. Decreased cell migration and invasion were detected in 95-D/TOB1 cells, and the suppression of TOB1 enhanced the metastasis in A549 cells. TOB1 overexpression not only increased the expression of the phosphatase and tensin homolog (PTEN), an important tumor suppressor, but also regulated the downstream effectors in the PI3K/PTEN signaling pathway, including Akt, ERK1/2, etc. In contrast, decreased expression of TOB1 oppositely regulated the expression of these factors. TOB1 also regulates the gelatinase activity of MMP2 and MMP9 in lung cancer cells.

CONCLUSION

The results demonstrate that the PI3K/PTEN pathway, which is essential for carcinogenesis, angiogenesis, and metastasis, may be one of the possible signaling pathways for regulation of proliferation and metastasis of human lung cancer cells by TOB1 in vitro.

Central role of the EGF receptor in neurometabolic aging

A strong connection between neuronal and metabolic health has been revealed in recent years. It appears that both normal and pathophysiological aging, as well as neurodegenerative disorders, are all profoundly influenced by this "neurometabolic" interface, that is, communication between the brain and metabolic organs. An important aspect of this "neurometabolic" axis that needs to be investigated involves an elucidation of molecular factors that knit these two functional signaling domains, neuronal and metabolic, together. This paper attempts to identify and discuss a potential keystone signaling factor in this "neurometabolic" axis, that is, the epidermal growth factor receptor (EGFR). The EGFR has been previously demonstrated to act as a signaling nexus for many ligand signaling modalities and cellular stressors, for example, radiation and oxidative radicals, linked to aging and degeneration. The EGFR is expressed in a wide variety of cells/tissues that pertain to the coordinated regulation of neurometabolic activity. EGFR signaling has been highlighted directly or indirectly in a spectrum of neurometabolic conditions, for example, metabolic syndrome, diabetes, Alzheimer's disease, cancer, and cardiorespiratory function. Understanding the positioning of the EGFR within the neurometabolic domain will enhance our appreciation of the ability of this receptor system to underpin highly complex physiological paradigms such as aging and neurodegeneration.

Phase transitions in oleic acid and in human breast tissue as studied by Raman spectroscopy and Raman imaging

We present the results of differential scanning calorimetry (DSC) and Raman studies in the temperature range of 293-77 K on vibrational properties of the oleic acid and the human breast tissue as a function of temperature. We have found that vibrational properties are very sensitive indicators to specify phases and phase transitions at the molecular level. We have found that water content confined in the cancerous tissue is markedly different from that in the noncancerous tissue. The OH stretching vibrations of water are useful as potential Raman biomarkers to distinguish between the cancerous and the noncancerous human breast tissues. Our results provide experimental evidence on the role of lipid profile and cell hydration as factors of particular significance in differentiation of the noncancerous and cancerous breast tissues.

Role of DDR1 in the gelatinases secretion induced by native type IV collagen in MDA-MB-231 breast cancer cells

Discoidin domain receptors (DDRs) are receptor tyrosine kinases that get activated by collagens in its native triple-helical form. In mammalian cells, DDR family consists of two members, namely DDR1 and DDR2, which mediates migration and proliferation of several cell types. DDR1 is activated by native type IV collagen and overexpressed in human breast cancer. Type IV collagen is the main component of basement membrane (BM), and the ability to degrade and penetrate BM is related with an increased potential for invasion and metastasis. Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that collectively are capable of degrading all components of the extracellular matrix, including the BM. In breast cancer cells, denatured type IV collagen induces MMP-9 secretion and invasion. However, the role of DDR1 in the regulation of gelatinases (MMP-2 and -9) secretion and invasion in breast cancer cells remains to be studied. We demonstrate here that native type IV collagen induces MMP-2 and -9 secretions and invasion through a DDR1 and Src-dependent pathway, together with an increase of MMP-2 and -9-cell surface levels. MMP-2 and -9 secretions require PKC kinase activity, epidermal growth factor receptor (EGFR) activation, arachidonic acid (AA) production and AA metabolites in MDA-MB-231 breast cancer cells. In summary, our data demonstrate, for the first time, that DDR1 mediates MMP-2 and -9 secretions and invasion induced by native type IV collagen in MDA-MB-231 breast cancer cells.