Cell cycle progression and the acquisition of a migratory phenotype are hallmarks of human carcin... more Cell cycle progression and the acquisition of a migratory phenotype are hallmarks of human carcinoma cells. Here we report a strong correlation between cell cycle progression into G2 phase and an increased migratory velocity for non-malignant, immortalized mammary epithelia nMuMG (Mus musculus mammary gland) cells, or malignant cervical carcinoma HeLa cells, expressing a fluorescent ubiquitin cell cycle indicator and quantified in wound closure assays with high content multi-parameter live cell imaging. Cells at the wound edge exhibited elevated microtubule nucleation capacity at centrosomes, and a reduction of this capacity through inhibition of aurora kinase A was sufficient to impair migration velocity without affecting cell cycle dynamics. In migratory cells, active aurora kinase A at the centrosome correlated with nucleation capacity. In clinically annotated mammary carcinoma tissues (n=3,992), aurora kinase A activity, as assessed by the abundance of phosphorylated-RHAMM (Rece...
Background: Medulloblastoma (MB) is the most common malignant pediatric brain tumor, accounting f... more Background: Medulloblastoma (MB) is the most common malignant pediatric brain tumor, accounting for 15-30% of all childhood intracranial neoplasms. High grade gliomas (HGG) are much rarer in children than in adults, comprising only 5%-10% of childhood brain tumors. Although multidisciplinary treatment has improved the 5-year survival rates in children significantly, the prognosis for recurrent MB and HGG remains poor with median overall survival <1 year. Temozolomide (TMZ) is frequently employed in the treatment of MB and pediatric HGG; however, clinical evidence is lacking and poor outcomes due to high-expression of the repair protein O6-methylguanine-DNA methyltransferase (MGMT), which is correlated with TMZ resistance, have been reported. Dianhydrogalactitol (VAL-083) is a structurally unique bi-functional alkylating agent causing DNA crosslinks at N7 position of guanine. VAL-083 readily crosses the blood brain barrier and has been shown to accumulate in brain tumor tissue. Fu...
Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. While frontline chemo... more Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. While frontline chemotherapy regimens are generally very effective, the prognosis for patients whose leukemia returns remains poor. The presence of measurable residual disease (MRD) in bone marrow at the completion of induction therapy is the strongest predictor of relapse, suggesting that strategies to eliminate the residual leukemic blasts from this niche could reduce the incidence of recurrence. We have previously reported that toll-like receptor (TLR) agonists achieve durable T cell-mediated protection in transplantable cell line-based models of B cell precursor leukemia (B-ALL). However, the successful application of TLR agonist therapy in an MRD setting would require the induction of anti-leukemic immune activity specifically in the bone marrow, a site of the chemotherapy-resistant leukemic blasts. In this study, we compare the organ-specific depletion of human and mouse primary B-ALL cells after syste...
The gonads are responsible for the production of germ cells through both mitosis and meiosis. Skp... more The gonads are responsible for the production of germ cells through both mitosis and meiosis. Skp2 is the receptor subunit of an SCF-type ubiquitin ligase and is a major regulator of the progression of cells into S phase of the cell cycle, which it promotes by mediating the ubiquitin-dependent degradation of p27, an inhibitor of cell proliferation. However, the role of the Skp2-p27 pathway in germ cell development remains elusive. We now show that disruption of Skp2 in mice results in a marked impairment in the fertility of males, with the phenotypes resembling Sertoli cell-only syndrome in men. Testes of Skp2-/- mice manifested pronounced germ cell hypoplasia accompanied by massive apoptosis in spermatogenic cells. Flow cytometry revealed an increased prevalence of polyploidy in spermatozoa, suggesting that the aneuploidy of these cells is responsible for the induction of apoptosis. Disruption of the p27 gene of Skp2-/- mice restored germ cell development, indicating that the testi...
Glioblastomas (GBM) are associated with high rates of relapse. These brain tumors are often resis... more Glioblastomas (GBM) are associated with high rates of relapse. These brain tumors are often resistant to chemotherapies like temozolomide (TMZ) and there are very few treatment options available to patients. We recently reported that polo-like kinase-1 (PLK1) is associated with the proliferative subtype of GBM; which has the worst prognosis. In this study, we addressed the potential of repurposing disulfiram (DSF), a drug widely used to control alcoholism for the past six decades. DSF has good safety profiles and penetrates the blood-brain barrier. Here we report that DSF inhibited the growth of TMZ resistant GBM cells, (IC90=100 nM), but did not affect normal human astrocytes. At similar DSF concentrations, self-renewal was blocked by ~100% using neurosphere growth assays. Likewise the drug completely inhibited the self-renewal of the BT74 and GBM4 primary cell lines. Additionally, DSF suppressed growth and self-renewal of primary cells from two GBM tumors.These cells were resistan...
Y-box-binding protein 1 (YB-1), which is a member of the DNA-binding protein family containing a ... more Y-box-binding protein 1 (YB-1), which is a member of the DNA-binding protein family containing a cold-shock domain, has pleiotropic functions in response to various environmental stimuli. As we previously showed that YB-1 is a global marker of multidrug resistance in ovarian cancer and other tumor types. To identify YB-1-regulated genes in ovarian cancers, we investigated the expression profile of YB-1 small-interfering RNA (siRNA)-transfected ovarian cancer cells using a high-density oligonucleotide array. YB-1 knockdown by siRNA upregulated 344 genes, including MDR1, thymidylate synthetase, S100 calcium binding protein and cyclin B, and downregulated 534 genes, including CXCR4, N-myc downstream regulated gene 1, E-cadherin and phospholipase C. Exogenous serum addition stimulated YB-1 translocation from the cytoplasm to the nucleus, and treatment with Akt inhibitors as well as Akt siRNA and integrin-linked kinase (ILK) siRNA specifically blocked YB-1 nuclear localization. Inhibition of Akt activation downregulated CXCR4 and upregulated MDR1 (ABCB1) gene expression. Administration of Akt inhibitor resulted in decrease in nuclear YB-1-positive cancer cells in a xenograft animal model. Akt activation thus regulates the nuclear translocation of YB-1, affecting the expression of drug-resistance genes and other genes associated with the malignant characteristics in ovarian cancer cells. Therefore, the Akt pathway could be a novel target of disrupting the nuclear translocation of YB-1 that has important implications for further development of therapeutic strategy against ovarian cancers.
Cell cycle progression and the acquisition of a migratory phenotype are hallmarks of human carcin... more Cell cycle progression and the acquisition of a migratory phenotype are hallmarks of human carcinoma cells. Here we report a strong correlation between cell cycle progression into G2 phase and an increased migratory velocity for non-malignant, immortalized mammary epithelia nMuMG (Mus musculus mammary gland) cells, or malignant cervical carcinoma HeLa cells, expressing a fluorescent ubiquitin cell cycle indicator and quantified in wound closure assays with high content multi-parameter live cell imaging. Cells at the wound edge exhibited elevated microtubule nucleation capacity at centrosomes, and a reduction of this capacity through inhibition of aurora kinase A was sufficient to impair migration velocity without affecting cell cycle dynamics. In migratory cells, active aurora kinase A at the centrosome correlated with nucleation capacity. In clinically annotated mammary carcinoma tissues (n=3,992), aurora kinase A activity, as assessed by the abundance of phosphorylated-RHAMM (Rece...
Background: Medulloblastoma (MB) is the most common malignant pediatric brain tumor, accounting f... more Background: Medulloblastoma (MB) is the most common malignant pediatric brain tumor, accounting for 15-30% of all childhood intracranial neoplasms. High grade gliomas (HGG) are much rarer in children than in adults, comprising only 5%-10% of childhood brain tumors. Although multidisciplinary treatment has improved the 5-year survival rates in children significantly, the prognosis for recurrent MB and HGG remains poor with median overall survival <1 year. Temozolomide (TMZ) is frequently employed in the treatment of MB and pediatric HGG; however, clinical evidence is lacking and poor outcomes due to high-expression of the repair protein O6-methylguanine-DNA methyltransferase (MGMT), which is correlated with TMZ resistance, have been reported. Dianhydrogalactitol (VAL-083) is a structurally unique bi-functional alkylating agent causing DNA crosslinks at N7 position of guanine. VAL-083 readily crosses the blood brain barrier and has been shown to accumulate in brain tumor tissue. Fu...
Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. While frontline chemo... more Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. While frontline chemotherapy regimens are generally very effective, the prognosis for patients whose leukemia returns remains poor. The presence of measurable residual disease (MRD) in bone marrow at the completion of induction therapy is the strongest predictor of relapse, suggesting that strategies to eliminate the residual leukemic blasts from this niche could reduce the incidence of recurrence. We have previously reported that toll-like receptor (TLR) agonists achieve durable T cell-mediated protection in transplantable cell line-based models of B cell precursor leukemia (B-ALL). However, the successful application of TLR agonist therapy in an MRD setting would require the induction of anti-leukemic immune activity specifically in the bone marrow, a site of the chemotherapy-resistant leukemic blasts. In this study, we compare the organ-specific depletion of human and mouse primary B-ALL cells after syste...
The gonads are responsible for the production of germ cells through both mitosis and meiosis. Skp... more The gonads are responsible for the production of germ cells through both mitosis and meiosis. Skp2 is the receptor subunit of an SCF-type ubiquitin ligase and is a major regulator of the progression of cells into S phase of the cell cycle, which it promotes by mediating the ubiquitin-dependent degradation of p27, an inhibitor of cell proliferation. However, the role of the Skp2-p27 pathway in germ cell development remains elusive. We now show that disruption of Skp2 in mice results in a marked impairment in the fertility of males, with the phenotypes resembling Sertoli cell-only syndrome in men. Testes of Skp2-/- mice manifested pronounced germ cell hypoplasia accompanied by massive apoptosis in spermatogenic cells. Flow cytometry revealed an increased prevalence of polyploidy in spermatozoa, suggesting that the aneuploidy of these cells is responsible for the induction of apoptosis. Disruption of the p27 gene of Skp2-/- mice restored germ cell development, indicating that the testi...
Glioblastomas (GBM) are associated with high rates of relapse. These brain tumors are often resis... more Glioblastomas (GBM) are associated with high rates of relapse. These brain tumors are often resistant to chemotherapies like temozolomide (TMZ) and there are very few treatment options available to patients. We recently reported that polo-like kinase-1 (PLK1) is associated with the proliferative subtype of GBM; which has the worst prognosis. In this study, we addressed the potential of repurposing disulfiram (DSF), a drug widely used to control alcoholism for the past six decades. DSF has good safety profiles and penetrates the blood-brain barrier. Here we report that DSF inhibited the growth of TMZ resistant GBM cells, (IC90=100 nM), but did not affect normal human astrocytes. At similar DSF concentrations, self-renewal was blocked by ~100% using neurosphere growth assays. Likewise the drug completely inhibited the self-renewal of the BT74 and GBM4 primary cell lines. Additionally, DSF suppressed growth and self-renewal of primary cells from two GBM tumors.These cells were resistan...
Y-box-binding protein 1 (YB-1), which is a member of the DNA-binding protein family containing a ... more Y-box-binding protein 1 (YB-1), which is a member of the DNA-binding protein family containing a cold-shock domain, has pleiotropic functions in response to various environmental stimuli. As we previously showed that YB-1 is a global marker of multidrug resistance in ovarian cancer and other tumor types. To identify YB-1-regulated genes in ovarian cancers, we investigated the expression profile of YB-1 small-interfering RNA (siRNA)-transfected ovarian cancer cells using a high-density oligonucleotide array. YB-1 knockdown by siRNA upregulated 344 genes, including MDR1, thymidylate synthetase, S100 calcium binding protein and cyclin B, and downregulated 534 genes, including CXCR4, N-myc downstream regulated gene 1, E-cadherin and phospholipase C. Exogenous serum addition stimulated YB-1 translocation from the cytoplasm to the nucleus, and treatment with Akt inhibitors as well as Akt siRNA and integrin-linked kinase (ILK) siRNA specifically blocked YB-1 nuclear localization. Inhibition of Akt activation downregulated CXCR4 and upregulated MDR1 (ABCB1) gene expression. Administration of Akt inhibitor resulted in decrease in nuclear YB-1-positive cancer cells in a xenograft animal model. Akt activation thus regulates the nuclear translocation of YB-1, affecting the expression of drug-resistance genes and other genes associated with the malignant characteristics in ovarian cancer cells. Therefore, the Akt pathway could be a novel target of disrupting the nuclear translocation of YB-1 that has important implications for further development of therapeutic strategy against ovarian cancers.
Uploads
Papers by Abbas Fotovati