A Novel Trypsin Kunitz-Type Inhibitor from Cajanus cajan Leaves and Its Inhibitory Activity on New Cancer Serine Proteases and Its Effect on Tumor Cell Growth.

A novel trypsin inhibitor from Cajanus cajan (TIC) fresh leaves was partially purified by affinity chromatography. SDS-PAGE revealed one band with about 15 kDa with expressive trypsin inhibitor activity by zymography. TIC showed high affinity for trypsin (Ki = 1.617 µM) and was a competitive inhibitor for this serine protease. TIC activity was maintained after 24 h of treatment at 70 °C, after 1 h treatments with different pH values, and ß-mercaptoethanol increasing concentrations, and demonstrated expressive structural stability. However, the activity of TIC was affected in the presence of oxidizing agents. In order to study the effect of TIC on secreted serine proteases, as well as on the cell culture growth curve, SK-MEL-28 metastatic human melanoma cell line and CaCo-2 colon adenocarcinoma was grown in supplemented DMEM, and the extracellular fractions were submitted salting out and affinity chromatography to obtain new secreted serine proteases. TIC inhibited almost completely, 96 to 89%, the activity of these serine proteases and reduced the melanoma and colon adenocarcinoma cells growth of 48 and 77% respectively. Besides, it is the first time that a trypsin inhibitor was isolated and characterized from C. cajan leaves and cancer serine proteases were isolated and partial characterized from SK-MEL-28 and CaCo-2 cancer cell lines. Furthermore, TIC shown to be potent inhibitor of tumor protease affecting cell growth, and can be one potential drug candidate to be employed in chemotherapy of melanoma and colon adenocarcinoma.

A glimpse into cofilin-1 role in cancer therapy: A potential target to improve clinical outcomes?

Cofilin-1 (CFL1) modulates dynamic actin networks by severing and enhancing depolymerization. The upregulation of cofilin-1 expression in several cancer types is associated with tumor progression and metastasis. However, recent discoveries indicated relevant cofilin-1 functions under oxidative stress conditions, interplaying with mitochondrial dynamics, and apoptosis networks. In this scenario, these emerging roles might impact the response to clinical therapy and could be used to enhance treatment efficacy. Here, we highlight new perspectives of cofilin-1 in the therapy resistance context and discussed how cofilin-1 is involved in these events, exploring aspects of its contribution to therapeutic resistance. We also provide an analysis of CFL1 expression in several tumors predicting survival. Therefore, understanding how exactly coflin-1 plays, particularly in therapy resistance, may pave the way to the development of treatment strategies and improvement of patient survival.

Açaí (Euterpe oleracea Mart.) Seed Oil Exerts a Cytotoxic Role over Colorectal Cancer Cells: Insights of Annexin A2 Regulation and Molecular Modeling.

Açaí, Euterpe oleracea Mart., is a native plant from the Amazonian and is rich in several phytochemicals with anti-tumor activities. The aim was to analyze the effects of açaí seed oil on colorectal adenocarcinoma (ADC) cells. In vitro analyses were performed on CACO-2, HCT-116, and HT-29 cell lines. The strains were treated with açaí seed oil for 24, 48, and 72 h, and cell viability, death, and morphology were analyzed. Molecular docking was performed to evaluate the interaction between the major compounds in açaí seed oil and Annexin A2. The viability assay showed the cytotoxic effect of the oil in colorectal adenocarcinoma cells. Acai seed oil induced increased apoptosis in CACO-2 and HCT-116 cells and interfered with the cell cycle. Western blotting showed an increased expression of LC3-B, suggestive of autophagy, and Annexin A2, an apoptosis regulatory protein. Molecular docking confirmed the interaction of major fatty acids with Annexin A2, suggesting a role of açaí seed oil in modulating Annexin A2 expression in these cancer cell lines. Our results suggest the anti-tumor potential of açaí seed oil in colorectal adenocarcinoma cells and contribute to the development of an active drug from a known natural product.

Long-term resistance to 5-fluorouracil promotes epithelial-mesenchymal transition, apoptosis evasion, autophagy, and reduced proliferation rate in colon cancer cells.

The drug, 5-fluorouracil (5FU) is a standard first-line treatment for colorectal cancer (CRC) patients. However, drug resistance acquisition remains an important challenge for effective clinical outcomes. Here, we established a long-term drug-resistant CRC model and explored the cellular events underlying 5FU resistance. We showed that 5FU-treated cells (HCT-116 5FUR) using a prolonged treatment protocol were significantly more resistant than parental cells. Likewise, cell viability and IC50 values were also observed to increase in HCT-116 5FUR cells when treated with increasing doses of oxaliplatin, indicating a cross-resistance mechanism to other cytotoxic agents. Moreover, HCT-116 5FUR cells exhibited metabolic and molecular changes, as evidenced by increased thymidylate synthase levels and upregulated mRNA levels of ABCB1. HCT-116 5FUR cells were able to overcome S phase arrest and evade apoptosis, as well as activate autophagy, as indicated by increased LC3B levels. Cells treated with low and high doses displayed epithelial-mesenchymal transition (EMT) features, as observed by decreased E-cadherin and claudin-3 levels, increased vimentin protein levels, and increased SLUG, ZEB2 and TWIST1 mRNA levels. Furthermore, HCT-116 5FUR cells displayed enhanced migration and invasion capabilities. Interestingly, we found that the 5FU drug-resistance gene signature is positively associated with the mesenchymal signature in CRC samples, and that ABCB1 and ZEB2 co-expressed at high levels could predict poor outcomes in CRC patients. Overall, the 5FU long-term drug-resistance model established here induced various cellular events, and highlighted the importance of further efforts to identify promising targets involved in more than one cellular event to successfully overcome drug-resistance.

Crosstalk between PI3K/Akt and Wnt/ß-catenin pathways promote colorectal cancer progression regardless of mutational status.

The PI3K/Akt and Wnt/ß-catenin pathways play an important role in the acquisition of the malignant phenotype in cancer. However, there are few data regarding the role of the interplay between both pathways in colorectal cancer (CRC) progression. The mutational status and the clinicopathological characteristics of PI3K/Akt and Wnt/ß-catenin pathways were accessed by bioinformatic analysis whereas that the impact of the interplay between the activity of both pathways to explain tumorigenic potential was performed in vitro using IGF-1 and Wnt3a treatments in CRC cell models. The mutational status of these pathways did not influence the survival of CRC patients, but an association between clinicopathological characteristics in patients with mutations in one, but not in both pathways was observed. A potentiating effect on the activation of both pathways and enhanced cellular migration and proliferation was observed when both pathways were activated simultaneously with IGF-1 and Wnt3a. In addition, these effects were hindered after pretreatment with LY294002, a specific PI3K inhibitor, suggesting some dependence between these two signaling cascades. Our findings show that, regardless of mutational status, there is an interplay between the activity of PI3K/Akt and Wnt/ß-catenin pathways that contributes to events related to CRC progression and that the reversal of such events using a PI3K inhibitor highlights the value of targeting these pathways for potential directed therapies in CRC patients.

Kopsanone inhibits proliferation and migration of invasive colon cancer cells.

Colorectal cancer (CRC) is the second leading cause of cancer-related death globally. In spite of the increasing knowledge on molecular characteristics of different cancer types including CRC, there is limitation in the development of an effective treatment. The present study aimed to verify the antitumor effect of kopsanone, an indole alkaloid. To achieve this, we treated human colon cancer cells (Caco-2 and HCT-116) with kopsanone and analyzed its effects on cell viability, cell-cell adhesion, and actin cytoskeleton organization. In addition, functional assays including micronuclei formation, colony formation, cell migration, and invasiveness were performed. We observed that kopsanone reduced viability and proliferation and induced micronuclei formation of HCT-116 cells. Also, kopsanone inhibited anchorage-dependent colony formation and modulated adherens junctions (AJs), thus increasing the localization of E-cadherin and ß-catenin in the cytosol of the invasive cells. Finally, fluorescence assays showed that kopsanone decreased stress fibers formation and reduced migration but not invasion of HCT-116 cells. Taken together, these findings indicate that kopsanone reduces proliferation and migration of HCT-116 cells via modulation of AJs and can therefore be considered for future in vivo and clinical investigation as potential therapeutic agent for treatment of CRC.

Cofilin-1, LIMK1 and SSH1 are differentially expressed in locally advanced colorectal cancer and according to consensus molecular subtypes.

BACKGROUND: Colorectal cancer (CRC) is among the deadliest cancers, wherein early dissemination of tumor cells, and consequently, metastasis formation, are the main causes of mortality and poor prognosis. Cofilin-1 (CFL-1) and its modulators, LIMK1/SSH1, play key roles in mediating the invasiveness by driving actin cytoskeleton reorganization in various cancer types. However, their clinical significance and prognostic value in CRC has not been fully explored. Here, we evaluated the clinical contribution of these actin regulators according to TNM and consensus molecular subtypes (CMSs) classification. METHODS: CFL-1, LIMK1 and SSH1 mRNA/protein levels were assessed by real-time PCR and immunohistochemical analyses using normal adjacent and tumor tissues obtained from a clinical cohort of CRC patients. The expression levels of these proteins were associated with clinicopathological features by using the chi square test. In addition, using RNA-Seq data of CRC patients from The Cancer Genome Atlas (TCGA) database, we determine how these actin regulators are expressed and distributed according to TNM and CMSs classification. Based on gene expression profiling, Kaplan-Meier survival analysis was used to evaluated overall survival. RESULTS: Bioinformatic analysis revealed that LIMK1 expression was upregulated in all tumor stages. Patients with high levels of LIMK1 demonstrated significantly lower overall survival rates and exhibited greater lymph node metastatic potential in a clinical cohort. In contrast, CFL-1 and SSH1 have expression downregulated in all tumor stages. However, immunohistochemical analyses showed that patients with high protein levels of CFL-1 and SSH1 exhibited greater lymph node metastatic potential and greater depth of local invasion. In addition, using the CMSs classification to evaluate different biological phenotypes of CRC, we observed that LIMK1 and SSH1 genes are upregulated in immune (CMS1) and mesenchymal (CMS4) subtypes. However, patients with high levels of LIMK1 also demonstrated significantly lower overall survival rates in canonical (CMS2), and metabolic (CMS3) subtypes. CONCLUSIONS: We demonstrated that CFL-1 and its modulators, LIMK1/SSH1, are differentially expressed and associated with lymph node metastasis in CRC. Finally, this expression profile may be useful to predict patients with aggressive signatures, particularly, the immune and mesenchymal subtypes of CRC.

IL-17 Triggers Invasive and Migratory Properties in Human MSCs, while IFNy Favors their Immunosuppressive Capabilities: Implications for the "Licensing" Process.

Mesenchymal stromal cells (MSCs) were first used as a source for cell therapy in 1995; however, despite their versatility and unambiguous demonstration of efficacy and safety in preclinical/phase I studies, the positive effect of MSCs in human phase III studies did not resemble the success obtained in mouse models of disease. This dissonance highlights the need to more thoroughly study the immunobiology of MSCs to make better use of these cells. Thus, we aimed to study the immunobiology of MSCs by using chip array analysis as a method for general screening to obtain a global picture in our model study and found IFNy and IL-17 signaling as the first two "top canonical pathways" involved in MSCs immunomodulation. The role of IFNy in triggering the immunosuppressive properties of MSCs is well recognized by many groups; however, the role of IL-17 in this process remains uncertain. Interestingly, in contrast to IFNy, which actively improved the MSCs-mediated immunosuppression, IL-17 did not improve directly the MSCs-mediated immunosuppression. Instead, IL-17 signaling induced the migration of MSCs and inflammatory cells, bringing these cell types together and increasing the likelihood of the lymphocytes sensing the immunosuppressive molecules produced by the MSCs. These effects also correlated with high levels of cytokine/chemokine production and metalloprotease activation by MSCs. Importantly, this treatment maintained the MSCs safety profile by not inducing the expression of molecules related to antigen presentation. In this way, our findings highlight the possibility of using IL-17, in combination with IFNy, to prime MSCs for cell therapy to improve their biological properties and thus their therapeutic efficacy. Finally, the use of preactivated MSCs may also minimize variations among MSCs to produce more uniform therapeutic products. In the not-so-distant future, we envisage a portfolio of MSCs activated by different cocktails specifically designed to target and treat specific diseases. Graphical abstract.

Docosahexaenoic acid promotes cell cycle arrest and decreases proliferation through WNT/ß-catenin modulation in colorectal cancer cells exposed to γ-radiation.

The effects of radiation are known to be potentiated by N-3 polyunsaturated fatty acids, which modulate several signaling pathways, but the molecular mechanisms through which these fatty acids enhance the anticancer effects of irradiation in colorectal cancer (CRC) treatment remain poorly elucidated. Here, we aimed to ascertain whether the fatty acid docosahexaenoic acid (DHA) exerts a modulating effect on the response elicited by radiation treatment (RT). Two CRC cell lines, Caco-2 and HT-29, were exposed to RT, DHA, or both (DHA + RT) for various times, and then cell viability, proliferation, and clonogenicity were assessed. Moreover, cell cycle, apoptosis, and necrosis were analyzed using flow cytometry, and the involvement of WNT/ß-catenin signaling was investigated by immunofluorescence to determine nuclear ß-catenin, GSK3ß phosphorylation status, and TCF/LEF-activity reporter. DHA and RT applied separately diminished the viability of both HT-29 and Caco-2 cells, and DHA + RT caused a further reduction in proliferation mainly in HT-29 cells, particularly in terms of colony formation. Concomitantly, our results verified cell cycle arrest in G0/G1 phase, a reduction of cyclin D1 expression, and a decrease in GSK3ß phosphorylation after the combined treatment. Furthermore, immunofluorescence quantification revealed that nuclear ß-catenin was increased in RT-exposed cells, but this effect was abrogated in cells exposed to DHA + RT, and the results of TCF/LEF-activity assays confirmed that DHA attenuated the increase in nuclear ß-catenin activity induced by irradiation. Our finding shows that DHA applied in combination with RT enhanced the antitumor effects of irradiation on CRC cells, and that the underlying mechanism involved the WNT/ß-catenin pathway. © 2018 BioFactors, 45(1):24-34, 2019.

Cofilin-1 signaling mediates epithelial-mesenchymal transition by promoting actin cytoskeleton reorganization and cell-cell adhesion regulation in colorectal cancer cells.

Colorectal cancer (CRC) is frequently a lethal disease because of metastasis. Actin cytoskeletal rearrangement is an essential step in cell migration during activation of the epithelial-mesenchymal transition (EMT) program, which is associated with metastatic properties of cancer cells. Cofilin-1 protein modulates actin dynamics by promoting actin treadmilling, thereby driving membrane protrusion and cell migration and invasion. However, the role of cofilin-1 during EMT in CRC is unknown. Here, we show that cofilin-1 and p-cofilin-1 have distinct subcellular distribution in EMT cells, as determined by super-resolution microscopy images, indicating distinct roles in different areas of cells. Silenced cofilin-1 cells treated with TGF-ß (siCofilin-1/TGF-ß) evaded p-LIMK2-p-cofilin-1 status, leading to recovery of E-cadherin and claudin-3 at the cell-cell contact and their respective protein levels, actin reorganization, and decreased mesenchymal protein level. Furthermore, siCofilin-1/TGF-ß cells exhibited decreased migration and invasion rates as well as MMP-2 and -9 activity and augmented focal adhesion size. The expression of an inactive phospho-cofilin-1 mimetic (S3E) reduced E-cadherin and claudin-3 in cell-cell contacts, reduced their protein levels, and increased vimentin protein. Based on our findings, we suggest that cofilin-1 is crucial to switching from epithelial to mesenchymal-like morphology and cell migration and invasion by regulating actin cytoskeleton organization through activation of RhoA-LIMK2-cofilin-1 signaling, impacting the cell-cell adhesion organization of colon cancer cells in EMT.

Cytotoxicity of citral against melanoma cells: The involvement of oxidative stress generation and cell growth protein reduction.

Citral is a natural compound that has shown cytotoxic and antiproliferative effects on breast and hematopoietic cancer cells; however, there are few studies on melanoma cells. Oxidative stress is known to be involved in all stages of melanoma development and is able to modulate intracellular pathways related to cellular proliferation and death. In this study, we hypothesize that citral exerts its cytotoxic effect on melanoma cells by the modulation of cellular oxidative status and/or intracellular signaling. To test this hypothesis, we investigated the antiproliferative and cytotoxic effects of citral on B16F10 murine melanoma cells evaluating its effects on cellular oxidative stress, DNA damage, cell death, and important signaling pathways, as these pathways, namely, extracellular signal-regulated kinases 1/2 (ERK1/2), AKT, and phosphatidylinositol-3 kinase, are involved in cell proliferation and differentiation. The p53 and nuclear factor kappa B were also investigated due to their ability to respond to intracellular stress. We observed that citral exerted antiproliferative and cytotoxic effects in B16F10; induced oxidative stress, DNA lesions, and p53 nuclear translocation; and reduced nitric oxide levels and nuclear factor kappa B, ERK1/2, and AKT. To investigate citral specificity, we used non-neoplastic human and murine cells, HaCaT (human skin keratinocytes) and NIH-3T3 cells (murine fibroblasts), and observed that although citral effects were not specific for cancer cells, non-neoplastic cells were more resistant to citral than B16F10. These findings highlight the potential clinical utility of citral in melanoma, with a mechanism of action involving the oxidative stress generation, nitric oxide depletion, and interference in signaling pathways related to cell proliferation.

The Role of EphA4 Signaling in Radiation-Induced EMT-Like Phenotype in Colorectal Cancer Cells.

Radiotherapy is widely used for advanced rectal tumors. However, refractory metastasis has become the major cause of therapy failure in rectal cancer patients. Understanding the molecular mechanism that controls the aggressive cellular response to this treatment is essential for developing new therapeutic applications and improving radiotherapy response in colorectal cancer patients. Using the progeny of cells that were submitted to irradiation, we have demonstrated that the PI3K/AKT, Wnt/ß-catenin signaling pathways as well as ERK1/2 downstream of EPHA4 receptor activation, play an important role in the regulation of events related with the EMT development, which may be associated with the therapeutic failure in rectal cancer after radiotherapy. Here, we further discuss about EphA4 receptor as a potential therapeutic target for the treatment of this cancer type. J. Cell. Biochem. 118: 442-445, 2017. © 2016 Wiley Periodicals, Inc.

EphA4-mediated signaling regulates the aggressive phenotype of irradiation survivor colorectal cancer cells.

Radiotherapy is widely used for advanced rectal tumors. However, tumor recurrence after this treatment tends to be more aggressive and is associated with a poor prognosis. Uncovering the molecular mechanism that controls this recurrence is essential for developing new therapeutic applications. In the present study, we demonstrated that radiation increases the EphA4 activation level of the survivor progeny of colorectal cancer cells submitted to this treatment and that such activation promoted the internalization of a complex E-cadherin-EphA4, inducing cell-cell adhesion disruption. Moreover, EphA4 knockdown in the progeny of irradiated cells reduced the migratory and invasive potentials and metalloprotease activity induced by irradiation. Finally, we demonstrated that the cell migration and invasion potential were regulated by AKT and ERK1/2 signaling, with the ERK1/2 activity being dependent on EphA4. In summary, our study demonstrates that these signaling pathways could be responsible for the therapeutic failure, thereby promoting local invasion and metastasis in rectal cancer after radiotherapy. We also postulate that EphA4 is a potential therapeutic target for colorectal cancer treatment.

Mechanism of metformin action in MCF-7 and MDA-MB-231 human breast cancer cells involves oxidative stress generation, DNA damage, and transforming growth factor ß1 induction.

The participation of oxidative stress in the mechanism of metformin action in breast cancer remains unclear. We investigated the effects of clinical (6 and 30 µM) and experimental concentrations of metformin (1000 and 5000 µM) in MCF-7 and in MDA-MB-231 cells, verifying cytotoxicity, oxidative stress, DNA damage, and intracellular pathways related to cell growth and survival after 24 h of drug exposure. Clinical concentrations of metformin decreased metabolic activity of MCF-7 cells in the MTT assay, which showed increased oxidative stress and DNA damage, although cell death and impairment in the proliferative capacity were observed only at higher concentrations. The reduction in metabolic activity and proliferation in MDA-MB-231 cells was present only at experimental concentrations after 24 h of drug exposition. Oxidative stress and DNA damage were induced in this cell line at experimental concentrations. The drug decreased cytoplasmic extracellular signal-regulated kinases 1 and 2 (ERK1/2) and AKT and increased nuclear p53 and cytoplasmic transforming growth factor ß1 (TGF-ß1) in both cell lines. These findings suggest that metformin reduces cell survival by increasing reactive oxygen species, which induce DNA damage and apoptosis. A relationship between the increase in TGF-ß1 and p53 levels and the decrease in ERK1/2 and AKT was also observed. These findings suggest the mechanism of action of metformin in both breast cancer cell lineages, whereas cell line specific undergoes redox changes in the cells in which proliferation and survival signaling are modified. Taken together, these results highlight the potential clinical utility of metformin as an adjuvant during the treatment of luminal and triple-negative breast cancer.

Dual inhibition of histone deacetylases and phosphoinositide 3-kinases: effects on Burkitt lymphoma cell growth and migration.

Burkitt lymphoma is a highly aggressive non-Hodgkin lymphoma that is characterized by MYC deregulation. Recently, the PI3K pathway has emerged as a cooperative prosurvival mechanism in Burkitt lymphoma. Despite the highly successful results of treatment that use high-dose chemotherapy regimens in pediatric Burkitt lymphoma patients, the survival rate of pediatric patients with progressive or recurrent disease is low. PI3Ks are also known to regulate cell migration, and abnormal cell migration may contribute to cancer progression and dissemination in Burkitt lymphoma. Little is known about Burkitt lymphoma cell migration, but the cooperation between MYC and PI3K in Burkitt lymphoma pathogenesis suggests that a drug combination could be used to target the different steps involved in Burkitt lymphoma cell dissemination and disease progression. The aim of this study was to investigate the effects of the histone deacetylase inhibitor suberoylanilide hydroxamic acid combined with the PI3K inhibitor LY294002 on Burkitt lymphoma cell growth and migration. The combination enhanced the cell growth inhibition and cell-cycle arrest induced by the PI3K inhibitor or histone deacetylase inhibitor individually. Moreover, histone deacetylase inhibitor/PI3K inhibitor cotreatment suppressed Burkitt lymphoma cell migration and decreased cell polarization, Akt and ERK1/2 phosphorylation, and leads to RhoB induction. In summary, the histone deacetylase inhibitor/PI3Ki combination inhibits cell proliferation and migration via alterations in PI3K signaling and histone deacetylase activity, which is involved in the acetylation of α-tubulin and the regulation of RhoB expression.

The role of N-glycans in colorectal cancer progression: potential biomarkers and therapeutic applications.

Changes in glycosylation, which is one of the most common protein post-translational modifications, are considered to be a hallmark of cancer. N-glycans can modulate cell migration, cell-cell adhesion, cell signaling, growth and metastasis. The colorectal cancer (CRC) is a leading cause of cancer-related mortality and the correlation between CRC progression and changes in the pattern of expression of N-glycans is being considered in the search for new biomarkers. Here, we review the role of N-glycans in CRC cell biology. The perspectives on emerging N-glycan-related anticancer therapies, along with new insights and challenges, are also discussed.

Alterations of the apical junctional complex and actin cytoskeleton and their role in colorectal cancer progression.

Colorectal cancer represents the fourth highest mortality rate among cancer types worldwide. An understanding of the molecular mechanisms that regulate their progression can prevents or reduces mortality due to this disease. Epithelial cells present an apical junctional complex connected to the actin cytoskeleton, which maintains the dynamic properties of this complex, tissue architecture and cell homeostasis. Several studies have indicated that apical junctional complex alterations and actin cytoskeleton disorganization play a critical role in epithelial cancer progression. However, few studies have examined the existence of an interrelation between these 2 components, particularly in colorectal cancer. This review discusses the recent progress toward elucidating the role of alterations of apical junctional complex constituents and of modifications of actin cytoskeleton organization and discusses how these events are interlinked to modulate cellular responses related to colorectal cancer progression toward successful metastasis.

Progeny from irradiated colorectal cancer cells acquire an EMT-like phenotype and activate Wnt/ß-catenin pathway.

Radiotherapy remains a major approach to adjuvant therapy for patients with advanced colorectal cancer, however, the fractionation schedules frequently allow for the repopulation of surviving tumors cells, neoplastic progression, and subsequent metastasis. The aim of the present study was to analyze the transgenerational effects induced by radiation and evaluate whether it could increase the malignant features on the progeny derived from irradiated parental colorectal cancer cells, Caco-2, HT-29, and HCT-116. The progeny of these cells displayed a differential radioresistance as seen by clonogenic and caspase activation assay and had a direct correlation with survivin expression as observed by immunoblotting. Immunofluorescence showed that the most radioresistant progenies had an aberrant morphology, disturbance of the cell-cell adhesion contacts, disorganization of the actin cytoskeleton, and vimentin filaments. Only the progeny derived from intermediary radioresistant cells, HT-29, reduced the E-cadherin expression and overexpressed ß-catenin and vimentin with increased cell migration, invasion, and metalloprotease activation as seen by immunoblotting, wound healing, invasion, and metalloprotease activity assay. We also observed that this most aggressive progeny increased the Wnt/ß-catenin-dependent TCF/LEF activity and underwent an upregulation of mesenchymal markers and downregulation of E-cadherin, as determined by qRT-PCR. Our results showed that the intermediate radioresistant cells can generate more aggressive cellular progeny with the EMT-like phenotype. The Wnt/ß-catenin pathway may constitute an important target for new adjuvant treatment schedules with radiotherapy, with the goal of reducing the migratory and invasive potential of the remaining cells after treatment.

Cytotoxic effects of Euterpe oleracea Mart. in malignant cell lines.

BACKGROUND: Euterpe oleracea Mart., a plant from the Amazon region, is commonly known as açaí or juçara; it has high nutritional value and elevated levels of lipids, proteins, and minerals. Açaí is an abundant and much consumed fruit by the Amazon local population, and studies have demonstrated that it is rich in phytochemicals with antioxidant, anti-inflammatory, and anticancer activities. Therefore, the aim of this study was to test this plant for anticancer activity in different human malignant cell lines. METHODS: Cell lines derived from breast and colorectal adenocarcinomas were treated with 10, 20, and 40 µg/mL of bark, seed, and total açaí fruit hydroalcoholic extracts for 24 and 48 h. After treatment, cell viability was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, and cell morphological features were observed by light and transmission electron microscopy. The type of cell death was also evaluated. The data were analyzed statistically by one-way analysis of variance (ANOVA), followed by Dunnett's or Tukey's post hoc tests, as appropriate. RESULTS: We observed that of all the cell lines tested, MCF-7 was the only line that responded to açaí treatment. The extracts caused significant reduction (p<0.01) in cell viability and altered cell morphological features by inducing the appearance of autophagic vacuoles, as observed by transmission electron microscopy. Furthermore, increased expression of LC3BII, a protein marker of autophagosome formation, was observed by western blotting. Caspase Glo™ assays and morphologic observations by DAPI nuclear staining and transmission electron microscopy did not indicate any apoptotic events. CONCLUSIONS: The present study demonstrated that açaí possesses antitumorigenic potential in the MCF-7 cell line. Further studies are needed to identify the compound (s) responsible for this cytotoxic activity and the molecular target in the cell. This discovery of the anticancer potential of açaí may help in the development of chemopreventive drugs and may have therapeutic effects in the treatment of breast cancer.