Impact of flavonoids on matrix metalloproteinase secretion and invadopodia formation in highly invasive A431-III cancer cells

Comparative Analysis of Acetylated Flavonoids' Chemopreventive Effects in Different Cancer Cell Lines

Flavonoids, a class of natural compounds with anticancer activity, exhibit varying biological activities and potencies based on their structural differences. Acylation, including acetylation of flavonoids, generally increases their structural diversity, which is closely related to the diversity of bioactivity within this group of compounds. However, it remains largely unknown how acetylation affects the bioactivity of many flavonoids. Based on our previous findings that O-acetylation enhances quercetin's bioactivity against various cancer cells, we synthesized 12 acetylated flavonoids, including seven novel compounds, to investigate their anticancer activities in the MDA-MB-231, HCT-116, and HepG2 cell lines. Our results showed that acetylation notably enhanced the cell proliferation inhibitory effect of quercetin and kaempferol across all cancer cell lines tested. Interestingly, while the 5,7,4'-O-triacetate apigenin (3Ac-A) did not show an enhanced the effect of inhibition of cell proliferation through acetylation, it exhibited significantly strong anti-migration activity in MDA-MB-231 cells. In contrast, the 7,4'-O-diacetate apigenin (2Ac-Q), which lacks acetylation at the 5-position hydroxy group, showed enhanced cell proliferation inhibitory effect but had weaker anti-migration effects compared to 3Ac-A. These results indicated that acetylated flavonoids, especially quercetin, kaempferol, and apigenin derivatives, are promising for anticancer applications, with 3Ac-A potentially having unique anti-migration pathways independent of apoptosis induction. This study highlights the potential application of flavonoids in novel chemopreventive strategies for their anti-cancer activity.

Rhamnetin Prevents Bradykinin-Induced Expression of Matrix Metalloproteinase-9 in Rat Brain Astrocytes by Suppressing Protein Kinase-Dependent AP-1 Activation

Bradykinin (BK) has been recognized as a stimulant for matrix metalloproteinase (MMP)-9 expression, contributing to neuroinflammation. Modulating the BK/MMP-9 pathway offers potential in the treatment of neuroinflammatory disorders. Rhamnetin (RNT), a flavonoid compound known for its antioxidant and anti-inflammatory effects, has shown promise. However, the specific mechanisms through which RNT inhibits BK-induced MMP-9 expression remain unclear. Therefore, this study aims to delve into the intricate mechanisms underlying this process. Here, we initially demonstrated that RNT effectively attenuated BK-induced MMP-9 expression and its associated cell migration in rat brain astrocyte-1 (RBA-1) cells. Further investigation revealed that BK-driven MMP-9 protein, mRNA, and promoter activity linked to cell migration relied on c-Src, Pyk2, EGFR, PDGFR, PI3K/Akt, JNK1/2, and c-Jun. This was validated by the inhibition of these effects through specific inhibitors, a finding substantiated by the introduction of siRNAs targeting these signaling molecules. Notably, the phosphorylated levels of these signaling components induced by BK were significantly reduced by their respective inhibitors and RNT, underscoring the inhibitory role of RNT in this process. These findings indicate that, in RBA-1 cells, RNT diminishes the heightened induction of MMP-9 triggered by BK through the inhibition of c-Src/Pyk2/PDGFR and EGFR/PI3K/Akt/JNK1/2-dependent AP-1 activation. This suggests that RNT holds promise as a potential therapeutic approach for addressing neuroinflammation in the brain.

Quercetin-loaded solid lipid nanoparticles exhibit antitumor activity and suppress the proliferation of triple-negative MDA-MB 231 breast cancer cells: implications for invasive breast cancer treatment

BACKGROUND

Quercetin (QC) is a naturally occurring flavonoid found in abundance in fruits and vegetables. Its anti-cancer and anti-inflammatory properties have been previously demonstrated, but its low bioavailability hampers its clinical use. Triple-negative breast cancer is a subtype of breast cancer with a poor response to chemotherapy. This study investigates the anti-cancer effects of quercetin-solid lipid nanoparticles (QC-SLN) on the triple-negative breast cancer cell line MDA-MB231.

MATERIALS AND METHODS

MCF-7 and MDA-MB231 cells were treated with 18.9 µM of QC and QC-SLN for 48 h. Cell viability, apoptosis, colony formation assay, and the anti-angiogenic effects of the treatment were evaluated.

RESULTS

QC-SLN displayed optimal properties (particle size of 154 nm, zeta potential of -27.7 mV, encapsulation efficiency of 99.6%, and drug loading of 1.81%) and exhibited sustained release of QC over 72 h. Compared to the QC group, the QC-SLN group showed a significant decrease in cell viability, colony formation, angiogenesis, and a substantial increase in apoptosis through the modulation of Bax and Bcl-2 at both gene and protein levels. The augmentation in the proportion of cleaved-to-pro caspases 3 and 9, as well as poly (ADP-ribose) polymerase (PARP), under the influence of QC-SLN, was conspicuously observed in both cancer cell lines.

CONCLUSIONS

This study showcases quercetin-solid lipid nanoparticles (QC-SLN) as a promising therapy for triple-negative breast cancer. The optimized QC-SLN formulation improved physicochemical properties and sustained quercetin release, resulting in reduced cell viability, colony formation, angiogenesis, and increased apoptosis in the MDA-MB231 cell line. These effects were driven by modulating Bax and Bcl-2 expression, activating caspases 3 and 9, and poly (ADP-ribose) polymerase (PARP). Further in vivo studies are needed to confirm QC-SLN's efficacy and safety.

Ectopic expression of matrix metalloproteinases and filopodia extension via JNK activation are involved in the invasion of blood tumor cells in Drosophila mxc mutant

Drosophila mxcmbn1 mutant exhibits severe hyperplasia in larval hematopoietic tissue called the lymph glands (LGs). However, the malignant nature of these cells remains unknown. We aimed to identify if mxcmbn1 LG cells behave as malignant tumor cells and uncover the mechanism(s) underlying the malignancy of the mutant hemocytes. When mutant LG cells were allografted into normal adult abdomens, they continued to proliferate; however, normal LG cells did not proliferate. Mutant circulating hemocytes also attached to the larval central nervous system (CNS), where the basement membrane was disrupted. The mutant hemocytes displayed higher expression of matrix metalloproteinase (MMP) 1 and MMP2 and higher activation of the c-Jun N-terminal kinase (JNK) pathway than normal hemocytes. Depletion of MMPs or JNK mRNAs in LGs resulted in reduced numbers of hemocytes attached to the CNS, suggesting that the invasive phenotype involved elevated expression of MMPs via hyperactivation of the JNK pathway. Moreover, hemocytes with elongated filopodia and extra lamellipodia were frequently observed in the mutant hemolymph, which also depended on JNK signaling. Thus, the MMP upregulation and overextension of actin-based cell protrusions were also involved in hemocyte invasion in mxcmbn1 larvae. These findings contribute to the understanding of molecular mechanisms underlying mammalian leukemic invasion.

Naringenin and proanthocyanidins pre-treatment decreases synthesis and activity of gelatinases induced by zoledronic acid in a dental implant surface in vitro model

OBJECTIVE

To assess the effects of pre-treatment with proanthocyanidins (PA) flavonoids, from grape seed extract, and synthetic naringenin (NA) on the synthesis of matrix metalloproteinases (MMPs) gelatinases and their tissue inhibitors (TIMPs), as well as the gelatinolytic activity of MMPs by human gingival fibroblasts (HGF) and osteoblasts (Ob) exposed to zoledronic acid (ZA) in a dental implant surface in vitro model.

DESIGN

The highest non-cytotoxic concentrations of NA and PA were determined for HGF (10 μg/mL; defined by previous study) and Ob (0.5 μg/mL; defined by prestoBlue assay). Then, HFG and Ob were individually seeded onto titanium discs, and after 24 h, cells were pre-treated (or not) with NA or PA, followed (or not) by exposure to ZA. Next, MMP-2, MMP-9, TIMP-1, TIMP-2 synthesis (ELISA), and gelatinolytic activity (in situ zymography) was evaluated. Data were analyzed by one-way ANOVA and Tukey tests (α = 0.05).

RESULTS

ZA treatment increased the synthesis (p < 0.05) and activity of MMPs; flavonoids pre-treatment controlled ZA-induced gelatinolytic effects, down-regulating MMPs synthesis (p < 0.05) and activity by HGF and Ob. For HGF, NA and PA pre-treatment did not up-regulate TIMP synthesis after ZA exposure (p > 0.05); for Ob, TIMP-2 was up-regulated (p < 0.05) by flavonoids, followed by ZA.

CONCLUSIONS

NA and PA pre-treatment provides interesting results in the modulation of ZA deleterious effects, down-regulating MMP-2 and MMP-9 synthesis and activity by HGF and Ob and up-regulating TIMP-2 by Ob.

Dietary patterns in association with the expression of pro-metastatic genes in primary breast cancer

PURPOSE

Metastasis is a major leading cause of mortality in female breast cancer (BrCa). Cellular motility is a pathological process of metastasis remarked by the overexpression of cortactin (CTTN), Ras homolog family member-A (RhoA), and Rho-associated kinase (ROCK) genes. Their balance is responsible for upholding the integrity of healthy epithelial cell junctions. This study aimed to explore the associations between a posteriori dietary patterns and the expression levels of pro-metastatic genes in primary BrCa.

METHODS

In this consecutive case series, 215 eligible women, newly diagnosed with histologically confirmed non-metastatic BrCa (stage I-IIIA), were recruited from Hospitals in Tabriz, Northwestern Iran (2015-2017). The tumoral expression levels of genes were quantified using real-time reverse transcription-polymerase chain reaction. Dietary data assessment was carried out using a validated food frequency questionnaire.

RESULTS

Three dietary patterns were identified using principal component analysis (KMO = 0.699). Adherence to the "vegan" pattern (vegetables, fruits, legumes, nuts, seeds, and whole grains) was inversely associated with the expression levels of RhoA (OR_Adj.T3vs.T1 = 0.24, 95%CI 0.07-0.79) and ROCK (OR_Adj.T3vs.T1 = 0.26, 95%CI 0.08-0.87). In addition, the highest adherence to the "prudent" pattern (spices, seafood, dairy, and vegetable oils) decreased the odds of overexpressions at RhoA (OR_Adj.T3vs.T1 = 0.26, 95%CI 0.08-0.84) and ROCK genes (OR_Adj.T3vs.T1 = 0.29, 95%CI 0.09-0.95). The highest adherence to "Western" pattern (meat, processed meat, hydrogenated fat, fast food, refined cereals, sweets, and soft drinks) was a risk factor associated with the overexpression of RhoA (OR_Adj.T3vs.T1 = 3.15, 95%CI 1.12-8.85).

CONCLUSION

Adherence to healthy dietary patterns was significantly associated with the downregulation of pro-metastatic genes. Findings provided new implications to advance the nutrigenomic knowledge to prevent the odds of over-regulations in pro-metastatic genes of the primary BrCa.

Skin cancer, including related pathways and therapy and the role of luteolin derivatives as potential therapeutics

Cutaneous malignant melanoma is the fastest growing and the most aggressive form of skin cancer that is diagnosed. However, its incidence is relatively scarce compared to the highest mortality rate of all skin cancers. The much more common skin cancers include nonmelanoma malignant skin cancers. Moreover, over the past several decades, the frequency of all skin cancers has increased much more dynamically than that of almost any other type of cancer. Among the available therapeutic options for skin cancers, chemotherapy used immediately after the surgical intervention has been an essential element. Unfortunately, the main problem with conventional chemopreventive regimens involves the lack of response to treatment and the associated side effects. Hence, there is a need for much more effective anticancer drugs. Correspondingly, the targeted alternatives have involved phytochemicals, which are safer chemotherapeutic agents and exhibit competitive anticancer activity with high therapeutic efficacy. Among polyphenolic compounds, some flavonoids and their derivatives, which are mostly found in medicinal plants, have been demonstrated to influence the modulation of signaling pathways at each stage of the carcinogenesis process, which is also important in the context of skin cancers. Hence, this review focuses on an exhaustive overview of the therapeutic effects of luteolin and its derivatives in the treatment and prevention of skin cancers. The bioavailability and structure–activity relationships of luteolin derivatives are also discussed. This review is the first such complete account of all of the scientific reports concerning this particular group of natural compounds that target a specific area of neoplastic diseases.

Anti-Inflammatory Effects of Rhamnetin on Bradykinin-Induced Matrix Metalloproteinase-9 Expression and Cell Migration in Rat Brain Astrocytes

Bradykinin (BK) has been shown to induce matrix metalloproteinase (MMP)-9 expression and participate in neuroinflammation. The BK/MMP-9 axis can be a target for managing neuroinflammation. Our previous reports have indicated that reactive oxygen species (ROS)-mediated nuclear factor-kappaB (NF-κB) activity is involved in BK-induced MMP-9 expression in rat brain astrocytes (RBA-1). Rhamnetin (RNT), a flavonoid compound, possesses antioxidant and anti-inflammatory effects. Thus, we proposed RNT could attenuate BK-induced response in RBA-1. This study aims to approach mechanisms underlying RNT regulating BK-stimulated MMP-9 expression, especially ROS and NF-κB. We used pharmacological inhibitors and siRNAs to dissect molecular mechanisms. Western blotting and gelatin zymography were used to evaluate protein and MMP-9 expression. Real-time PCR was used for gene expression. Wound healing assay was applied for cell migration. 2',7'-dichlorodihydrofluorescein diacetate (H2DCF-DA) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) were used for ROS generation and NOX activity, respectively. Promoter luciferase assay and chromatin immunoprecipitation (ChIP) assay were applied to detect gene transcription. Our results showed that RNT inhibits BK-induced MMP-9 protein and mRNA expression, promoter activity, and cell migration in RBA-1 cells. Besides, the levels of phospho-PKCδ, NOX activity, ROS, phospho-ERK1/2, phospho-p65, and NF-κB p65 binding to MMP-9 promoter were attenuated by RNT. In summary, RNT attenuates BK-enhanced MMP-9 upregulation through inhibiting PKCδ/NOX/ROS/ERK1/2-dependent NF-κB activity in RBA-1.

Quercetin and Luteolin Improve the Anticancer Effects of 5-Fluorouracil in Human Colorectal Adenocarcinoma In Vitro Model: A Mechanistic Insight

The aim of this study was to investigate the antitumor effects of quercetin and luteolin combined with 5-Fluorouracil (5-FU) in HT-29 human colorectal cancer cells. Cell viability induced by quercetin, luteolin and combination of these compounds with 5-FU were determined by MTT assay, also Cell death detection Elisa assay and fluorescence microscopy were performed to investigate apoptotic effects. Hu-VEGF Elisa assay was employed to determine the effects of treatments on angiogenesis. Western blot and qRT-PCR analysis were performed to investigate effects on p53, Bax, Bcl-2, p38 MAPK, mTOR, PTEN, and Akt proteins and genes. The results indicated that quercetin, luteolin and combinations of these compounds with 5-FU inhibited the growth of HT 29 cells. Compared to the control, apoptosis were triggered 8.1 and 10.1 fold in HT-29 cells, that treated with quercetin + 5-FU and luteolin + 5-FU, respectively. VEGF amount significantly decreased by combined treatments. qRT-PCR and western blot results demonstrated that quercetin, luteolin and the combinations of these flavonoids with 5-FU, modulate the apoptotic pathways in HT-29 cells. The increase in p53, Bax, p38 MAPK, and PTEN gene expression levels compared to the control group was 1.71, 1.42, 3.26, and 3.29-fold with 5-FU + L treatment, respectively, while this increase was 8.43, 1.65, 3.55, and 3.54-fold with 5-FU + Q treatment, respectively. In addition, when the anti-apoptotic Bcl-2, mTOR, and Akt gene expression levels were normalized as 1 in the control group, they were 0.28, 0.41, and 0.22 with 5-FU + L treatment, and 0.32, 0.46, and 0.39, respectively, with 5-FU + Q treatment. These findings suggested that quercetin and luteolin synergistically enhanced the anticancer effect of 5-FU in HT 29 cells and may therefore minimize the toxic effects of 5-FU in the clinical treatment of colorectal cancer.

Antiangiogenic Activity of Flavonoids: A Systematic Review and Meta-Analysis

Abstract: An imbalance of angiogenesis contributes to many pathologies such as cancer, arthritis and retinopathy, hence molecules that can modulate angiogenesis are of considerable therapeutic importance. Despite many reports on the promising antiangiogenic properties of naturally occurring flavonoids, no flavonoids have progressed to the clinic for this application. This systematic review and meta-analysis therefore evaluates the antiangiogenic activities of a wide range of flavonoids and is presented in two sections. The first part of the study (Systematic overview) included 402 articles identified by searching articles published before May 2020 using ScienceDirect, PubMed and Web of Science databases. From this initial search, different classes of flavonoids with antiangiogenic activities, related pathologies and use of in vitro and/or in/ex vivo angiogenesis assays were identified. In the second part (Meta-analysis), 25 studies concerning the antiangiogenic evaluation of flavonoids using the in vivo chick chorioallantoic membrane (CAM) assay were included, following a targeted search on articles published prior to June 2020. Meta-analysis of 15 out of the 25 eligible studies showed concentration dependent antiangiogenic activity of six compared subclasses of flavonoids with isoflavones, flavonols and flavones being the most active (64 to 80% reduction of blood vessels at 100 µM). Furthermore, the key structural features required for the antiangiogenic activity of flavonoids were derived from the pooled data in a structure activity relationship (SAR) study. All in all, flavonoids are promising candidates for the development of antiangiogenic agents, however further investigations are needed to determine the key structural features responsible for their activity.

Luteolin-7-O-Glucoside Inhibits Oral Cancer Cell Migration and Invasion by Regulating Matrix Metalloproteinase-2 Expression and Extracellular Signal-Regulated Kinase Pathway

Oral squamous cell carcinoma is the sixth most common type of cancer globally, which is associated with high rates of cancer-related deaths. Metastasis to distant organs is the main reason behind worst prognostic outcome of oral cancer. In the present study, we aimed at evaluating the effects of a natural plant flavonoid, luteolin-7-O-glucoside, on oral cancer cell migration and invasion. The study findings showed that in addition to preventing cell proliferation, luteolin-7-O-glucoside caused a significant reduction in oral cancer cell migration and invasion. Mechanistically, luteolin-7-O-glucoside caused a reduction in cancer metastasis by reducing p38 phosphorylation and downregulating matrix metalloproteinase (MMP)-2 expression. Using a p38 inhibitor, SB203580, we proved that luteolin-7-O-glucoside exerts anti-migratory effects by suppressing p38-mediated increased expression of MMP-2. This is the first study to demonstrate the luteolin-7-O-glucoside inhibits cell migration and invasion by regulating MMP-2 expression and extracellular signal-regulated kinase pathway in human oral cancer cell. The study identifies luteolin-7-O-glucoside as a potential anti-cancer candidate that can be utilized clinically for improving oral cancer prognosis.

Dietary Flavonoids Luteolin and Quercetin Inhibit Migration and Invasion of Squamous Carcinoma through Reduction of Src/Stat3/S100A7 Signaling

Flavonoids are well-known antioxidants and have shown the ability to prevent tumor formation and recurrence. Especially in dietary flavonoids, they have provided convenience and consistence of intake for long-term prevention of tumor formation. Previous reports suggested that S100 calcium-binding protein A7 (S100A7) might activate epithelial–mesenchymal transition (EMT) signaling and promote the metastasis of tumor cells; however, the regulatory signaling was unclear. In this study, we found that S100A7 was highly expressed in cancer cells and could be reduced by luteolin (Lu) and quercetin (Qu) through Src/Stat3 signaling. We found that the protein levels of S100A7, phosphorylated Src (p-Src), and p-Stat3 were increased in A431-III cells. Flavonoids Lu and Qu reduce protein levels of p-Src, p-Stat3 and S100A7 in A431-III cells. Treatment of A431-III cells with Src inhibitor SU6656 and Stat3 inhibitor S3I-201 also reduced the protein levels of S100A7. Transactivation activity of 5′-upstream regions of S100A7 was activated by Stat3 but was reduced by treatment with Lu, Qu, SU6656 and S3I-201. The treatment also reduced the migratory and invasive abilities of A431-III cells. In a further analysis of EMT markers, the protein level of E-cad increased and that of Twist decreased after treatment with the inhibitors and flavonoids. Overexpression of S100A7 decreased the protein level of E-cad and increased the Twist level, whereas knockdown of S100A7 had the opposite effects. Treatment with S3I-201, Lu and Qu, compared to the control, were found to decrease metastasis of tumor cells in zebrafish larvae. These results suggest that Lu and Qu may inhibit Src/Stat3/S100A7 signaling to reduce tumorigenesis of cancer cells.

Comparative In Vitro Evaluation of Antibacterial and Osteogenic Activity of Polysaccharide and Flavonoid Fractions Isolated from the leaves of Saussurea controversa

The osteogenic, cytotoxic, and antibacterial activities of polysaccharide (PS-SC) and flavonoid (F-SC) fractions isolated from the leaves extract of Saussurea controversa were studied in vitro. F-SC consists of the five quercetin glycosides in the ratio 2:8:10:1:4, which were isolated from the leaves extract of S. controversa and have been characterized previously. PS-SC was first isolated from the leaves extract of S. controversa and has been described. PS-SC consists in 30 compounds is characterized by a high degree of heterogeneity with a heterogeneity index of 19.74. The Mw and Mn of PS-SC were 108.6 and 5.5 kDa, respectively. Structural fragments are represented by galactose, arabinose, xylose, glucose, uronic acids, mannose, and rhamnose in a 10.1:3.3:2.2:2.1:1.7:0.9:0.5 molar ratio. F-SC as compared with PS-SC showed in vitro microbicidal (50 g/L) and better bacteriostatic (6.25 g/L versus 25 g/L of PS-SC) effects against the 24-h growth of Staphylococcus aureus strain 209 P and a 21-day absence of cytotoxicity on human adipose-derived multipotent mesenchymal stromal cells (hAMMSCs). Both fractions (PS-SC>F-SC) at doses of 10-50 mg/L stimulated differentiation of hAMMSCs into secreting osteoblasts accompanied by local mineralization of extracellular matrix. These fractions of S. controversa and especially F-SC, might be promising peroral drugs in the complex treatment of bone fractures and for prophylaxis of their infectious complications.

The Cytotoxic and Antimigratory Activity of Brazilin-Doxorubicin on MCF-7/HER2 Cells

Purpose: Breast cancer cells with overexpression of HER2 are known to be more aggressive, invasive, and resistant to chemotherapeutic agent. Brazilin, the major compound in the Caesalpinia sappan L. (CS) heartwood, has been studied for it's anticancer activity. The purpose of this study was to investigate the cytotoxic and antimigratory activity of brazilin (Bi) in combination with doxorubicin (Dox) on MCF-7/HER2 cells.

Methods: Cytotoxic activities of Bi individually and in combination with Dox were examined by MTT assay. Synergistic effects were analyzed by combination index (CI). Apoptosis and cell cycle profiles were observed by using flow cytometry. Migrating and invading cells were observed by using a Boyden chamber assay. Levels of MMP2 and MMP9 activity were observed by using a gelatin zymography assay. Levels of HER2, Bcl-2, Rac1, and p120 protein expression were observed by using an immunoblotting assay.

Results: The results of the MTT assay showed that Bi inhibited MCF-7/HER2 cell growth in a dose-dependent manner with an IC50 of 54 ± 3.7 µM. Furthermore, the combination of Bi and Dox showed a synergistic effect (CI <1). Flow cytometric analysis of Bi and its combination with Dox showed cellular accumulation in the G2/M phase and induction of apoptosis through suppression of Bcl-2 protein expression. In the Boyden chamber assay, gelatin zymography, and subsequent immunoblotting assay, the combination Bi and Dox inhibited migration, possibly through downregulation of MMP9, MMP2, HER2, Rac1, and p120 protein expression.

Conclusion: We conclude that Bi enhanced cytotoxic activity of Dox and inhibited migration of MCF-7/HER2 cells. Therefore, we believe that it has strong potential to be developed for the treatment of metastatic breast cancer with HER2 overexpression.

Flavonoids Luteolin and Quercetin Inhibit RPS19 and contributes to metastasis of cancer cells through c-Myc reduction

Flavonoids luteolin and quercetin can inhibit growth and metastasis of cancer cells. In our previous report, luteolin and quercetin was shown to block Akt/mTOR/c-Myc signaling. Here, we found luteolin and quercetin reduced protein level and transactivation activity of RPS19 in A431-III cells, which is isolated from parental A431 (A431-P) cell line. Further investigation the inhibitory mechanism of luteolin and quercetin on RPS19, we found c-Myc binding sites on RPS19 promoter. The Akt inhibitor LY294002, mTOR inhibitor rapamycin and c-Myc inhibitor 10058-F4 significantly suppressed RPS19 expression and transactivation activities. Overexpression and knockdown of c-Myc in cancer cells show RPS19 expression was regulated by c-Myc. Furthermore, Knockdown and overexpression of RPS19 was used to analyze of the function of RPS19 in cancer cells. The epithelial-mesenchymal transition (EMT) markers and metastasis abilities of cancer cells were also regulated by RPS19. These data suggest that luteolin and quercetin might inhibit metastasis of cancer cells by blocking Akt/mTOR/c-Myc signaling pathway to suppress RPS19-activated EMT signaling.

Nestin suppression attenuates invasive potential of endometrial cancer cells by downregulating TGF-β signaling pathway

Nestin, an intermediate filament protein and a stem cell marker is expressed in several tumors. Until recently, little was known about the expression levels and the role of Nestin in endometrial cancer. Compared to the immortalized endometrial epithelial cell line EM-E6/E7-TERT, endometrial cancer cell lines express high to moderate levels of Nestin. Furthermore, endometrial tumors and tumor cell lines have a cancer stem-like cell subpopulation expressing CD133. Among the cancer lines, AN3CA and KLE cells exhibited both a significantly higher number of CD133+ cells and expressed Nestin at higher levels than Ishikawa cells. Knockdown of Nestin in AN3CA and KLE increased cells in G0/G1 phase of the cell cycle, whereas overexpression in Ishikawa decreased cells in G0/G1 phase and increased cells in S-phase. Nestin knockdown cells showed increased p21, p27, and PNCA levels and decreased expression of cyclin-D1 and D3. In contrast, Nestin overexpression revealed an inverse expression pattern of cell cycle regulatory proteins. Nestin knockdown inhibited cancer cell growth and invasive potential by downregulating TGF-β signaling components, MMP-2, MMP-9, vimentin, SNAIL, SLUG, Twist, N-cadherin, and upregulating the epithelial cell marker E-cadherin whereas the opposite was observed with Nestin overexpressing Ishikawa cells. Nestin knockdown also inhibited, while overexpression promoted invadopodia formation and pFAK expression. Knockdown of Nestin significantly reduced tumor volume in vivo. Finally, progesterone inhibited Nestin expression in endometrial cancer cells. These results suggest that Nestin can be a therapeutic target for cancer treatment.

Dietary flavonoids, luteolin and quercetin, inhibit invasion of cervical cancer by reduction of UBE2S through epithelial-mesenchymal transition signaling

We previously reported that the dietary flavonoids, luteolin and quercetin, might inhibit the invasiveness of cervical cancer by reversing epithelial-mesenchymal transition (EMT) signaling. However, the regulatory mechanism exerted by luteolin and quercetin is still unclear. This study analyzed the invasiveness activation by ubiquitin E2S ligase (UBE2S) through EMT signaling and inhibition by luteolin and quercetin. We found that UBE2S expression was significantly higher in highly invasive A431 subgroup III (A431-III) than A431-parental (A431-P) cells. UBE2S small interfering (si)RNA knockdown and overexpression experiments showed that UBE2S increased the migratory and invasive abilities of cancer cells through EMT signaling. Luteolin and quercetin significantly inhibited UBE2S expression. UBE2S showed a negative correlation with von Hippel-Lindau (VHL) and a positive correlation with hypoxia-induced factor (Hif)-1α. Our findings suggest that high UBE2S in malignant cancers contributes to cell motility through EMT signaling and is reversed by luteolin and quercetin. UBE2S might contribute to Hif-1α signaling in cervical cancer. These results show the metastatic inhibition of cervical cancer by luteolin and quercetin through reducing UBE2S expression, and provide a functional role for UBE2S in the motility of cervical cancer. UBE2S could be a potential therapeutic target in cervical cancer.

Metadherin regulates actin cytoskeletal remodeling and enhances human gastric cancer metastasis via epithelial-mesenchymal transition

Metadherin (MTDH) can be recruited to mature tight junction complexes, and it regulates mesenchymal marker protein expression in many tumors and promote cancer metastasis. This study investigated the influence of MTDH expression on gastric cancer and to elucidate the potential mechanisms by which MTDH regulates actin cytoskeletal remodeling and enhances human gastric cancer metastasis via epithelial-mesenchymal transition (EMT). Relative MTDH mRNA expression levels were assessed by quantitative real-time PCR (Q-PCR), and MTDH protein expression levels and localization were evaluated via immunohistochemical (ICH) staining. We studied the role of MTDH in cancer cell migration and invasion by modulating MTDH expression in the gastric cancer cell lines MKN45 and AGS. We also confirmed the functions of MTDH through in vivo experiments. We found that MTDH expression levels were correlated with lymph node metastasis, TNM stages and decreased OS (P=0.002, <0.001 and 0.010, respectively) in human gastric cancer and that MTDH upregulation promoted EMT in vitro. Consistent with this finding, MTDH downregulation inhibited cell migration and invasion in vitro and suppressed tumor growth and metastasis in vivo. Furthermore, MTDH knockdown regulated actin cytoskeletal remodeling and inhibited EMT. Overall, our results provide a novel role for MTDH in regulating gastric cancer metastasis.

Molecular targets of luteolin in cancer

Many food-derived phytochemical compounds and their derivatives represent a cornucopia of new anticancer compounds. Despite extensive study of luteolin, the literature has no information on the exact mechanisms or molecular targets through which it deters cancer progression. This review discusses existing data on luteolin's anticancer activities and then offers possible explanations for and molecular targets of its cancer-preventive action. Luteolin prevents tumor development largely by inactivating several signals and transcription pathways essential for cancer cells. This review also offers insights into the molecular mechanisms and targets through which luteolin either prevents cancer or mediates cancer cell death.

Role of cellular cytoskeleton in epithelial-mesenchymal transition process during cancer progression

Currently, cancer metastases remain a major clinical problem that highlights the importance of recognition of the metastatic process in cancer diagnosis and treatment. A critical process associated with the metastasis process is the transformation of epithelial cells toward the motile mesenchymal state, a process called epithelial-mesenchymal transition (EMT). Increasing evidence suggests the crucial role of the cytoskeleton in the EMT process. The cytoskeleton is composed of the actin cytoskeleton, the microtubule network and the intermediate filaments that provide structural design and mechanical strength that is necessary for the EMT. The dynamic reorganization of the actin cytoskeleton is a prerequisite for the morphology, migration and invasion of cancer cells. The microtubule network is the cytoskeleton that provides the driving force during cell migration. Intermediate filaments are significantly rearranged, typically switching from cytokeratin-rich to vimentin-rich networks during the EMT process, accompanied by a greatly enhanced cell motility capacity. In the present review, the recent novel insights into the different cytoskeleton underlying EMT are summarized. There are numerous advances in our understanding of the fundamental role of the cytoskeleton in cancer cell invasion and migration.

Quercetin regulates β-catenin signaling and reduces the migration of triple negative breast cancer

Triple negative breast cancer (TNBC) is characterized by a lack in estrogen, progesterone, and epidermal growth factor 2 receptors. TNBC exhibits most of the characteristics of basal-like and claudin-low breast cancer subtypes. The main contributor in the mortality of TNBC is due to the higher invasive and migratory ability of these tumor cells. Some plant flavonoids inhibit the epithelial mesenchymal transition (EMT) of tumor cells and suppress cancer metastasis. In this study, we aimed to determine whether the flavonoid quercetin is effective in modulating the molecular signaling associated with EMT in TNBC. Our data indicated that quercetin can induce the expression of E-cadherin and also downregulate vimentin levels in TNBC. The ability of quercetin to modulate these EMT markers resulted in a mesenchymal-to-epithelial transition (MET). Quercetin-induced MET was linked with the alteration of nuclear localization of β-catenin and modulation of β-catenin target genes such as cyclin D1 and c-Myc. Furthermore, we observed that quercetin induced the anti-tumor activity of doxorubicin by inhibiting the migratory ability of TNBC cells. These results suggested that quercetin may inhibit TNBC metastasis and also improve the therapeutic efficacy of existing chemotherapeutic drugs.

Ethyl gallate suppresses proliferation and invasion in human breast cancer cells via Akt-NF-κB signaling

Euphorbia fischeriana Steud is a traditional Chinese Medicine that is known to possess a variety of anticarcinogenic properties. However, the bioactive constituents in Euphorbia fischeriana Steud and molecular mechanisms underlying this action in cancer treatment remain poorly understood. The present study investigated the chemotherapy activity and molecular targets of Ethyl gallate, which is identified as the major constituent extracted from the roots of Euphorbia fischeriana Steud in breast cancer cell lines in vitro. The results showed Ethyl gallate obviously decreased cell proliferation in MDA-MB-231 and MCF-7 cells in a dose- and time-dependent manner. Highly invasive MDA-MB-231 cells were found to be highly sensitive to treatment. Furthermore, significantly decreased metastatic potential of highly metastatic MDA-MB‑231 cells by Ethyl gallate was identified via the inhibition of cell motility using invasion and migration through a polyethylene terephthalate membrane. Ethyl gallate treatment decreased the activity of matrix metalloproteinase-2 (MMP-2) and MMP-9 by the downregulation of mRNA levels using RT-PCR, enzymes that are critical to tumor invasion. Treatment with Ethyl gallate decreased phosphatidylinositol 3-kinase (PI3K)/Akt and nuclear factor-κB (NF-κB) activation in MDA-MB-231 cells. These results indicate that Ethyl gallate suppresses proliferation and invasion in human breast cancer cells by modulating the PI3K/Akt pathway, which may contribute to inhibiting their downstream targets such as NF-κB p-65, Bcl-2/Bax, and mRNA levels of MMP-2 and MMP-9 in breast cancer cells. Thus, the present study shed new light on Ethyl gallate, an important bioactive constituent of Euphorbia fischeriana Steud, in human breast cancer treatment. The findings may provide basal theories for wide therapeutic application in human breast cancer.

Isolation of circulating tumor cells by dielectrophoresis

Dielectrophoresis (DEP) is an electrokinetic method that allows intrinsic dielectric properties of suspended cells to be exploited for discrimination and separation. It has emerged as a promising method for isolating circulation tumor cells (CTCs) from blood. DEP-isolation of CTCs is independent of cell surface markers. Furthermore, isolated CTCs are viable and can be maintained in culture, suggesting that DEP methods should be more generally applicable than antibody-based approaches. The aim of this article is to review and synthesize for both oncologists and biomedical engineers interested in CTC isolation the pertinent characteristics of DEP and CTCs. The aim is to promote an understanding of the factors involved in realizing DEP-based instruments having both sufficient discrimination and throughput to allow routine analysis of CTCs in clinical practice. The article brings together: (a) the principles of DEP; (b) the biological basis for the dielectric differences between CTCs and blood cells; (c) why such differences are expected to be present for all types of tumors; and (d) instrumentation requirements to process 10 mL blood specimens in less than 1 h to enable routine clinical analysis. The force equilibrium method of dielectrophoretic field-flow fractionation (DEP-FFF) is shown to offer higher discrimination and throughput than earlier DEP trapping methods and to be applicable to clinical studies.

LFG-500 inhibits the invasion of cancer cells via down-regulation of PI3K/AKT/NF-κB signaling pathway

Cancer cell invasion, one of the crucial events in local growth and metastatic spread of tumors, possess a broad spectrum of mechanisms, especially altered expression of matrix metalloproteinases. LFG-500 is a novel synthesized flavonoid with strong anti-cancer activity, whose exact molecular mechanism remains incompletely understood. This current study was designed to examine the effects of LFG-500 on tumor metastasis using in vitro and in vivo assays. LFG-500 could inhibit adhesion, migration and invasion of MDA-MB-231 human breast carcinoma cells. Meanwhile, it reduced the activities and expression of MMP-2 and MMP-9 via suppressing the transcriptional activation of NF-κB rather than AP-1 or STAT3. Moreover, LFG-500 repressed TNF-α induced cell invasion through inhibiting NF-κB and subsequent MMP-9 activity. Further elucidation of the mechanism revealed that PI3K/AKT but not MAPK signaling pathway was involved in the inhibitory effect of LFG-500 on NF-κB activation. LFG-500 could also suppress lung metastasis of B16F10 murine melanoma cells in vivo. Taken together, these results demonstrated that LFG-500 could block cancer cell invasion via down-regulation of PI3K/AKT/NF-κB signaling pathway, which provides new evidence for the anti-cancer activity of LFG-500.

Role of cortactin in dynamic actin remodeling events in gonadotrope cells

GnRH induces marked activation of the actin cytoskeleton in gonadotropes; however, the physiological consequences and cellular mechanisms responsible have yet to be fully elucidated. The current studies focus on the actin scaffolding protein cortactin. Using the gonadotrope-derived αT3-1 cell line, we found that cortactin is phosphorylated at Y(421), S(405), and S(418) in a time-dependent manner in response to the GnRH agonist buserelin (GnRHa). GnRHa induced translocation of cortactin to the leading edge of the plasma membrane where it colocalizes with actin and actin-related protein 3 (Arp3). Incubation of αT3-1 cells with the c-src inhibitor phosphoprotein phosphatase 1, blocked tyrosine phosphorylation of cortactin, reduced cortactin association with Arp3, and blunted actin reorganization in response to GnRHa. Additionally, we used RNA silencing strategies to knock down cortactin in αT3-1 cells. Knockdown of cortactin blocked the ability of αT3-1 cells to generate filopodia, lamellipodia, and membrane ruffles in response to GnRHa. We show that lamellipodia and filopodia are capable of LHβ mobilization in primary pituitary culture after GnRHa treatment, and disruption of these structures using jasplakinolide reduces LH secretion. Collectively, our findings suggest that after GnRHa activation, src activity leads to tyrosine phosphorylation of cortactin, which facilitates its association with Arp3 to engage the actin cytoskeleton. The reorganization of actin by cortactin potentially underlies GnRHa-induced secretory events within αT3-1 cells.