Many active principles produced by animals, plants and microorganisms have been employed in the d... more Many active principles produced by animals, plants and microorganisms have been employed in the development of new drugs for the treatment of human diseases. Among animals known to produce pharmacologically active molecules that interfere in human cell physiology, the caterpillar Lonomia obliqua has become the focus of toxicological studies due to recent findings about its venom constituents. The objective of this study was to investigate the effects of L. obliqua venom upon the viability and the proliferation of different cell lineages and to propose mechanisms for the herein observed induction of cell proliferation in glioma cell lines. MTT analyses indicate that L. obliqua venom increases the viability of tumor cell lines U138-MG and HT-29; on the other hand, it inhibits the viability of V-79 nontumor cells. Cell count based on the trypan blue exclusion method suggests a proliferating activity of the venom upon U138-MG cells. Exposure of U138-MG to crude venom extract led to a decrease in the production of nitric oxide, and activation of the cAMP signaling pathway inhibited the effects of the venom, indicating that these mechanisms may influence cell proliferation triggered by the venom. Despite the proliferative effects of crude venom on U138-MG and HT-29 cell cultures, a protein purified from L. obliqua hemolymph previously shown to have cytoprotective activity had no effect on U138-MG and HT-29; however, this same protein increased the viability of V-79 cells that had previously been exposed to the cytotoxic activity of the crude venom extract. This study indicates that the venom and the antiapoptotic protein act differently and have different effects on cell cultures, depending on the cell line analyzed. Biomolecules displaying either mitogenic or cytotoxic activities are of great biotechnological interest. Further studies encompassing the purification of active principles from L. obliqua venom are necessary to further elucidate its effects on different cell types.
Ecto-5'-nucleotid... more Ecto-5'-nucleotidase/CD73 (ecto-5'-NT) participates in extracellular ATP catabolism by converting adenosine monophosphate (AMP) into adenosine. This enzyme affects the progression and invasiveness of different tumors. Furthermore, the expression of ecto-5'-NT has also been suggested as a favorable prognostic marker, attributing to this enzyme contradictory functions in cancer. Medulloblastoma (MB) is the most common brain tumor of the cerebellum and affects mainly children. The effects of ecto-5'-NT overexpression on human MB tumor growth were studied in an in vivo model. Balb/c immunodeficient (nude) 6 to 14-week-old mice were used for dorsal subcutaneous xenograph tumor implant. Tumor development was evaluated by pathophysiological analysis. In addition, the expression patterns of adenosine receptors were verified. The human MB cell line D283, transfected with ecto-5'-NT (D283hCD73), revealed reduced tumor growth compared to the original cell line transfected with an empty vector. D283hCD73 generated tumors with a reduced proliferative index, lower vascularization, the presence of differentiated cells and increased active caspase-3 expression. Prominent A1 adenosine receptor expression rates were detected in MB cells overexpressing ecto-5'-NT. This work suggests that ecto-5'-NT promotes reduced tumor growth to reduce cell proliferation and vascularization, promote higher differentiation rates and initiate apoptosis, supposedly by accumulating adenosine, which then acts through A1 adenosine receptors. Therefore, ecto-5'-NT might be considered an important prognostic marker, being associated with good prognosis and used as a potential target for therapy.
Acai offers health benefits associated with its high antioxidante capacity, phytochemical composi... more Acai offers health benefits associated with its high antioxidante capacity, phytochemical composition, nutritional and sensory value. Therefore, the objective of this study was to evaluate the protective effect of acai frozen pulp on carbon tetrachloride (CCl4)-induced damage via modulation of anti- and pro-inflammatory cytokines in rat brain tissue. The rats were treated via oral (gavage) daily with water or acai frozen pulp for 14 days at a dose of 7 μL/g. On the 15th day, the animals in each group received a single intraperitoneal injection of CCl4 in a dose of 3.0 mL/kg or the same volume of mineral oil. After 4 h, the animals were euthanized by decapitation and the cerebral cortex, hippocampus and cerebellum were dissected and homogenated to evaluate the levels of tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), interleukin 18 (IL-18), interleukin 6 (IL-6) and interleukin 10 (IL-10). Data were statistically analyzed by analysis of variance followed by the Tukey post hoc test. It was observed that CCl4 increased TNF-α, IL-1β and IL-18 levels in all brain tissues, and that acai frozen pulp was able to prevent this increase. IL-6 and IL-10 brain tissue levels remained unchanged during all treatments. CCl4 experimental model was suitable to investigate brain tissue anti and pro-inflammatory cytokines. Acai frozen pulp prevented an increase in IL-1β, IL-18 and TNF-α, while IL-6 and IL-10 levels remained unchanged. The precise pathway by which inflammation contribute to hepatic encephalopathy, as well as to how this pathway can be modulated, is still under investigation.
Epigenetic deregulation may be involved in tumor cell biology, including differentiation, tumor p... more Epigenetic deregulation may be involved in tumor cell biology, including differentiation, tumor progression, and cell death, and histone acetylation is a major regulatory mechanism of gene transcription. Patterns of global histone modifications have been recently suggested as outcome predictors in cancer patients, but few studies have been conducted on pancreatic ductal adenocarcinomas (PDACs). This study was designed to investigate the predictive value of histone acetylation modifications on PDAC. A retrospective clinicopathologic analysis was undertaken in 119 patients diagnosed with PDAC between 2005 and 2011, and immunohistochemistry performed with polyclonal antibodies against H4K12ac, H3K9ac, and H3K18ac. Positive nuclear staining for each histone was measured as the intensity and expression, being classified into low-staining or high-staining groups. Results were analyzed in relation to patients' clinicopathologic parameters. There was a positive relationship between tumor differentiation and H4K12ac high scores (P<0.05) and staining with the 3 markers correlated positively with tumor stage (P<0.01). Univariate analysis showed worse survival in patients with high detection levels of H4K12ac (P=0.038) and H3K18Ac (P=0.033). A backwards Cox proportional hazards model analysis revealed the independent prognostic effect of high H4K12ac and H3K18ac levels (hazard ratios of 1.6 and 1.7, respectively, P<0.05), especially for patients at early stages of disease. We propose that acetylation of H4K12 and H3K18 may be considered valuable prognostic factors for pancreatic cancer, although the mechanism involved needs further investigation. Increasing insights into histone acetylation modifications can ultimately generate new ideas for rational and molecularly based diagnostic and therapeutic approaches.
This article will focus on basic concepts in the development of new agents for pediatric malignan... more This article will focus on basic concepts in the development of new agents for pediatric malignancies and future directions, while considering the limitations we have today and the lessons we have learned from adult cancers. In addition, basic ethical principles for ...
Neurotrophin and neuropeptide pathways are emerging targets in cancer. Here we show that brain-de... more Neurotrophin and neuropeptide pathways are emerging targets in cancer. Here we show that brain-derived neurotrophic factor (BDNF) and its receptor, TrkB, are present in colorectal cancer and that BDNF levels are increased in tumors compared to nontumor tissue. In addition, we investigate the role of BDNF in influencing the response of colorectal cancer cells to inhibition of gastrin-releasing peptide receptors (GRPR). Fresh-frozen sporadic colorectal adenocarcinoma specimens and adjacent nonneoplastic tissue from 30 patients, as well as paraffin-embedded colorectal cancer samples from 21 patients, were used in this study. Cell proliferation and mRNA and protein levels were examined in HT-29 or SW620 cells treated with a GRPR antagonist, human recombinant BDNF (hrBDNF), a Trk antagonist K252a, or cetuximab. Expression of BDNF and TrkB was detected in tumor samples and cell lines. BDNF levels were higher in tumor samples compared to nonneoplastic tissue. BDNF expression and secretion were increased by GRPR blockade in HT-29 cells through a mechanism dependent on epidermal growth factor receptors. Treatment with hrBDNF prevented the effect of GRPR blockade on cell proliferation, whereas a Trk inhibitor reduced proliferation. BDNF and TrkB are present in colorectal cancer and might contribute to resistance to GRPR antagonists.
HER2 as a cancer stem-cell target. By - Rafael Roesler, Daniela Baumann Cornelio, Ana Lucia Abuja... more HER2 as a cancer stem-cell target. By - Rafael Roesler, Daniela Baumann Cornelio, Ana Lucia Abujamra, Gilberto Schwartsmann.
Epigenetic alterations have been increasingly implicated in glioblastoma (GBM) pathogenesis, and ... more Epigenetic alterations have been increasingly implicated in glioblastoma (GBM) pathogenesis, and epigenetic modulators including histone deacetylase inhibitors (HDACis) have been investigated as candidate therapies. GBMs are proposed to contain a subpopulation of glioblastoma stem cells (GSCs) that sustain tumor progression and therapeutic resistance and can form tumorspheres in culture. Here, we investigate the effects of the HDACi trichostatin A (TSA) in U87 GBM cultures and tumorsphere-derived cells. Using approaches that include a novel method to measure tumorsphere sizes and the area covered by spheres in GBM cultures, as well as a nuclear morphometric analysis, we show that TSA reduced proliferation and colony sizes, led to G2/M arrest, induced alterations in nuclear morphology consistent with cell senescence, and increased the protein content of GFAP, but did not affect migration, in cultured human U87 GBM cells. In cells expanded in tumorsphere assays, TSA reduced sphere formation and induced neuron-like morphological changes. The expression of stemness markers in these cells was detected by reverse transcriptase polymerase chain reaction. These findings indicate that HDACis can inhibit proliferation, survival, and tumorsphere formation, and promote differentiation of U87 GBM cells, providing further evidence for the development of HDACis as potential therapeutics against GBM.
The gonadotropin-releasing hormone-like agonist D-Trp6-Pro9-NEt-LHRH (LHRHa) has been shown to in... more The gonadotropin-releasing hormone-like agonist D-Trp6-Pro9-NEt-LHRH (LHRHa) has been shown to induce a reversible short-term suppression of gonadotropins and gonadal steroids in patients with central precocious puberty. Since accelerated statural growth and bone maturation are clinical features of precocity not well controlled by conventional therapies, we examined the effects of prolonged LHRHa therapy for 18 consecutive months on growth and skeletal maturation in nine girls with neurogenic or idiopathic precocious puberty. Suppression of gonadotropin pulsations and gonadal steroids was maintained in all subjects. Growth velocity fell from a mean rate (+/- S.E.M.) of 9.35 +/- 0.64 cm per year during the 19 months before treatment to 4.58 +/- 0.60 cm per year during treatment (P less than 0.001). Bone age advanced a mean of 9.4 +/- 2.3 months during treatment. These changes resulted in a mean increase of 3.3 cm in predicted height (P less than 0.01). Complete suppression of the pituitary-gonadal axis can be maintained by LHRHa therapy, resulting in slowing of excessively rapid growth and skeletal maturation and in increased predicted adult height in girls with precocious puberty.
Many active principles produced by animals, plants and microorganisms have been employed in the d... more Many active principles produced by animals, plants and microorganisms have been employed in the development of new drugs for the treatment of human diseases. Among animals known to produce pharmacologically active molecules that interfere in human cell physiology, the caterpillar Lonomia obliqua has become the focus of toxicological studies due to recent findings about its venom constituents. The objective of this study was to investigate the effects of L. obliqua venom upon the viability and the proliferation of different cell lineages and to propose mechanisms for the herein observed induction of cell proliferation in glioma cell lines. MTT analyses indicate that L. obliqua venom increases the viability of tumor cell lines U138-MG and HT-29; on the other hand, it inhibits the viability of V-79 nontumor cells. Cell count based on the trypan blue exclusion method suggests a proliferating activity of the venom upon U138-MG cells. Exposure of U138-MG to crude venom extract led to a decrease in the production of nitric oxide, and activation of the cAMP signaling pathway inhibited the effects of the venom, indicating that these mechanisms may influence cell proliferation triggered by the venom. Despite the proliferative effects of crude venom on U138-MG and HT-29 cell cultures, a protein purified from L. obliqua hemolymph previously shown to have cytoprotective activity had no effect on U138-MG and HT-29; however, this same protein increased the viability of V-79 cells that had previously been exposed to the cytotoxic activity of the crude venom extract. This study indicates that the venom and the antiapoptotic protein act differently and have different effects on cell cultures, depending on the cell line analyzed. Biomolecules displaying either mitogenic or cytotoxic activities are of great biotechnological interest. Further studies encompassing the purification of active principles from L. obliqua venom are necessary to further elucidate its effects on different cell types.
Ecto-5'-nucleotid... more Ecto-5'-nucleotidase/CD73 (ecto-5'-NT) participates in extracellular ATP catabolism by converting adenosine monophosphate (AMP) into adenosine. This enzyme affects the progression and invasiveness of different tumors. Furthermore, the expression of ecto-5'-NT has also been suggested as a favorable prognostic marker, attributing to this enzyme contradictory functions in cancer. Medulloblastoma (MB) is the most common brain tumor of the cerebellum and affects mainly children. The effects of ecto-5'-NT overexpression on human MB tumor growth were studied in an in vivo model. Balb/c immunodeficient (nude) 6 to 14-week-old mice were used for dorsal subcutaneous xenograph tumor implant. Tumor development was evaluated by pathophysiological analysis. In addition, the expression patterns of adenosine receptors were verified. The human MB cell line D283, transfected with ecto-5'-NT (D283hCD73), revealed reduced tumor growth compared to the original cell line transfected with an empty vector. D283hCD73 generated tumors with a reduced proliferative index, lower vascularization, the presence of differentiated cells and increased active caspase-3 expression. Prominent A1 adenosine receptor expression rates were detected in MB cells overexpressing ecto-5'-NT. This work suggests that ecto-5'-NT promotes reduced tumor growth to reduce cell proliferation and vascularization, promote higher differentiation rates and initiate apoptosis, supposedly by accumulating adenosine, which then acts through A1 adenosine receptors. Therefore, ecto-5'-NT might be considered an important prognostic marker, being associated with good prognosis and used as a potential target for therapy.
Acai offers health benefits associated with its high antioxidante capacity, phytochemical composi... more Acai offers health benefits associated with its high antioxidante capacity, phytochemical composition, nutritional and sensory value. Therefore, the objective of this study was to evaluate the protective effect of acai frozen pulp on carbon tetrachloride (CCl4)-induced damage via modulation of anti- and pro-inflammatory cytokines in rat brain tissue. The rats were treated via oral (gavage) daily with water or acai frozen pulp for 14 days at a dose of 7 μL/g. On the 15th day, the animals in each group received a single intraperitoneal injection of CCl4 in a dose of 3.0 mL/kg or the same volume of mineral oil. After 4 h, the animals were euthanized by decapitation and the cerebral cortex, hippocampus and cerebellum were dissected and homogenated to evaluate the levels of tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), interleukin 18 (IL-18), interleukin 6 (IL-6) and interleukin 10 (IL-10). Data were statistically analyzed by analysis of variance followed by the Tukey post hoc test. It was observed that CCl4 increased TNF-α, IL-1β and IL-18 levels in all brain tissues, and that acai frozen pulp was able to prevent this increase. IL-6 and IL-10 brain tissue levels remained unchanged during all treatments. CCl4 experimental model was suitable to investigate brain tissue anti and pro-inflammatory cytokines. Acai frozen pulp prevented an increase in IL-1β, IL-18 and TNF-α, while IL-6 and IL-10 levels remained unchanged. The precise pathway by which inflammation contribute to hepatic encephalopathy, as well as to how this pathway can be modulated, is still under investigation.
Epigenetic deregulation may be involved in tumor cell biology, including differentiation, tumor p... more Epigenetic deregulation may be involved in tumor cell biology, including differentiation, tumor progression, and cell death, and histone acetylation is a major regulatory mechanism of gene transcription. Patterns of global histone modifications have been recently suggested as outcome predictors in cancer patients, but few studies have been conducted on pancreatic ductal adenocarcinomas (PDACs). This study was designed to investigate the predictive value of histone acetylation modifications on PDAC. A retrospective clinicopathologic analysis was undertaken in 119 patients diagnosed with PDAC between 2005 and 2011, and immunohistochemistry performed with polyclonal antibodies against H4K12ac, H3K9ac, and H3K18ac. Positive nuclear staining for each histone was measured as the intensity and expression, being classified into low-staining or high-staining groups. Results were analyzed in relation to patients' clinicopathologic parameters. There was a positive relationship between tumor differentiation and H4K12ac high scores (P<0.05) and staining with the 3 markers correlated positively with tumor stage (P<0.01). Univariate analysis showed worse survival in patients with high detection levels of H4K12ac (P=0.038) and H3K18Ac (P=0.033). A backwards Cox proportional hazards model analysis revealed the independent prognostic effect of high H4K12ac and H3K18ac levels (hazard ratios of 1.6 and 1.7, respectively, P<0.05), especially for patients at early stages of disease. We propose that acetylation of H4K12 and H3K18 may be considered valuable prognostic factors for pancreatic cancer, although the mechanism involved needs further investigation. Increasing insights into histone acetylation modifications can ultimately generate new ideas for rational and molecularly based diagnostic and therapeutic approaches.
This article will focus on basic concepts in the development of new agents for pediatric malignan... more This article will focus on basic concepts in the development of new agents for pediatric malignancies and future directions, while considering the limitations we have today and the lessons we have learned from adult cancers. In addition, basic ethical principles for ...
Neurotrophin and neuropeptide pathways are emerging targets in cancer. Here we show that brain-de... more Neurotrophin and neuropeptide pathways are emerging targets in cancer. Here we show that brain-derived neurotrophic factor (BDNF) and its receptor, TrkB, are present in colorectal cancer and that BDNF levels are increased in tumors compared to nontumor tissue. In addition, we investigate the role of BDNF in influencing the response of colorectal cancer cells to inhibition of gastrin-releasing peptide receptors (GRPR). Fresh-frozen sporadic colorectal adenocarcinoma specimens and adjacent nonneoplastic tissue from 30 patients, as well as paraffin-embedded colorectal cancer samples from 21 patients, were used in this study. Cell proliferation and mRNA and protein levels were examined in HT-29 or SW620 cells treated with a GRPR antagonist, human recombinant BDNF (hrBDNF), a Trk antagonist K252a, or cetuximab. Expression of BDNF and TrkB was detected in tumor samples and cell lines. BDNF levels were higher in tumor samples compared to nonneoplastic tissue. BDNF expression and secretion were increased by GRPR blockade in HT-29 cells through a mechanism dependent on epidermal growth factor receptors. Treatment with hrBDNF prevented the effect of GRPR blockade on cell proliferation, whereas a Trk inhibitor reduced proliferation. BDNF and TrkB are present in colorectal cancer and might contribute to resistance to GRPR antagonists.
HER2 as a cancer stem-cell target. By - Rafael Roesler, Daniela Baumann Cornelio, Ana Lucia Abuja... more HER2 as a cancer stem-cell target. By - Rafael Roesler, Daniela Baumann Cornelio, Ana Lucia Abujamra, Gilberto Schwartsmann.
Epigenetic alterations have been increasingly implicated in glioblastoma (GBM) pathogenesis, and ... more Epigenetic alterations have been increasingly implicated in glioblastoma (GBM) pathogenesis, and epigenetic modulators including histone deacetylase inhibitors (HDACis) have been investigated as candidate therapies. GBMs are proposed to contain a subpopulation of glioblastoma stem cells (GSCs) that sustain tumor progression and therapeutic resistance and can form tumorspheres in culture. Here, we investigate the effects of the HDACi trichostatin A (TSA) in U87 GBM cultures and tumorsphere-derived cells. Using approaches that include a novel method to measure tumorsphere sizes and the area covered by spheres in GBM cultures, as well as a nuclear morphometric analysis, we show that TSA reduced proliferation and colony sizes, led to G2/M arrest, induced alterations in nuclear morphology consistent with cell senescence, and increased the protein content of GFAP, but did not affect migration, in cultured human U87 GBM cells. In cells expanded in tumorsphere assays, TSA reduced sphere formation and induced neuron-like morphological changes. The expression of stemness markers in these cells was detected by reverse transcriptase polymerase chain reaction. These findings indicate that HDACis can inhibit proliferation, survival, and tumorsphere formation, and promote differentiation of U87 GBM cells, providing further evidence for the development of HDACis as potential therapeutics against GBM.
The gonadotropin-releasing hormone-like agonist D-Trp6-Pro9-NEt-LHRH (LHRHa) has been shown to in... more The gonadotropin-releasing hormone-like agonist D-Trp6-Pro9-NEt-LHRH (LHRHa) has been shown to induce a reversible short-term suppression of gonadotropins and gonadal steroids in patients with central precocious puberty. Since accelerated statural growth and bone maturation are clinical features of precocity not well controlled by conventional therapies, we examined the effects of prolonged LHRHa therapy for 18 consecutive months on growth and skeletal maturation in nine girls with neurogenic or idiopathic precocious puberty. Suppression of gonadotropin pulsations and gonadal steroids was maintained in all subjects. Growth velocity fell from a mean rate (+/- S.E.M.) of 9.35 +/- 0.64 cm per year during the 19 months before treatment to 4.58 +/- 0.60 cm per year during treatment (P less than 0.001). Bone age advanced a mean of 9.4 +/- 2.3 months during treatment. These changes resulted in a mean increase of 3.3 cm in predicted height (P less than 0.01). Complete suppression of the pituitary-gonadal axis can be maintained by LHRHa therapy, resulting in slowing of excessively rapid growth and skeletal maturation and in increased predicted adult height in girls with precocious puberty.
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Papers by Ana Lucia Abujamra