Effect of Ovarian Cancer Ascites on Cell Migration and Gene Expression in an Epithelial Ovarian Cancer In Vitro Model

A third of patients with epithelial ovarian cancer (EOC) present ascites. The cellular fraction of ascites often consists of EOC cells, lymphocytes, and mesothelial cells, whereas the acellular fraction contains cytokines and angiogenic factors. Clinically, the presence of ascites correlates with intraperitoneal and retroperitoneal tumor spread. We have used OV-90, a tumorigenic EOC cell line derived from the malignant ascites of a chemonaive ovarian cancer patient, as a model to assess the effect of ascites on migration potential using an in vitro wound-healing assay. A recent report of an invasion assay described the effect of ascites on the invasion potential of the OV-90 cell line. Ascites sampled from 31 ovarian cancer patients were tested and compared with either 5% fetal bovine serum or no serum for their nonstimulatory or stimulatory effect on the migration potential of the OV-90 cell line. A supervised analysis of data generated by the Affymetrix HG-U133A GeneChip identified differentially expressed genes from OV-90 cells exposed to ascites that had either a nonstimulatory or a stimulatory effect on migration. Ten genes (IRS2, CTSD, NRAS, MLXIP, HMGCR, LAMP1, ETS2, NID1, SMARCD1, and CD44) were upregulated in OV-90 cells exposed to ascites, allowing a nonstimulatory effect on cell migration. These findings were validated by quantitative polymerase chain reaction. In addition, the gene expression of IRS2 and MLXIP each correlated with prognosis when their expression was assessed in an independent set of primary cultures established from ovarian ascites. This study revealed novel candidates that may play a role in ovarian cancer cell migration.     

Anti-tubercular Activity of Ruthenium (II) Complexes with Polypyridines

A series of nine polypyridyl-ruthenium (II) complexes (N-ligands = 2,2′-bipyridines; 2,2′-6′,2′-terpyridines, di-alkyloxy-2,2′-6,2-bipyridine-3,3′-di-carboxylates), were tested against Mycobacterium tuberculosis (MBT). The complex (11) showed remarkable activity against MBT as compared to other complexes, (1–10). The aquo ligand of complex (11), as opposed to other chloro and acetonitrile derivatives, appears to play a key role in the antitubercular potency of this new class of metal-based compounds.     

A physical map of the Chinese chestnut (Castanea mollissima) genome and its integration with the genetic map

Three Chinese chestnut bacterial artificial chromosome (BAC) libraries were developed and used for physical map construction. Specifically, high information content fingerprinting was used to assemble 126,445 BAC clones into 1,377 contigs and 12,919 singletons. Integration of the dense Chinese chestnut genetic map with the physical map was achieved via high-throughput hybridization using overgo probes derived from sequence-based genetic markers. A total of 1,026 probes were anchored to the physical map including 831 probes corresponding to 878 expressed sequence tag-based markers. Within the physical map, three BAC contigs were anchored to the three major fungal blight-resistant quantitative trait loci on chestnut linkage groups B, F, and G. A subset of probes corresponding to orthologous genes in poplar showed only a limited amount of conserved gene order between the poplar and chestnut genomes. The integrated genetic and physical map of Chinese chestnut is available at www.fagaceae.org/physical_maps.     

Targeting proapoptotic protein BAD inhibits survival and self-renewal of cancer stem cells

Emerging evidence suggests that the resistance of cancer stem cells (CSC) to many conventional therapies is one of the major limiting factors of cancer therapy efficacy. Identification of mechanisms responsible for survival and self-renewal of CSC will help design new therapeutic strategies that target and eliminate both differentiated cancer cells and CSC. Here we demonstrated the potential role of proapoptotic protein BAD in the biology of CSC in melanoma, prostate and breast cancers. We enriched CD44⁺/CD24⁻ cells (CSC) by tumorosphere formation and purified this population by FACS. Both spheres and CSC exhibited increased potential for proliferation, migration, invasion, sphere formation, anchorage-independent growth, as well as upregulation of several stem cell-associated markers. We showed that the phosphorylation of BAD is essential for the survival of CSC. Conversely, ectopic expression of a phosphorylation-deficient mutant BAD induced apoptosis in CSC. This effect was enhanced by treatment with a BH3-mimetic, ABT-737. Both pharmacological agents that inhibit survival kinases and growth factors that are involved in drug resistance delivered their respective cytotoxic and protective effects by modulating the BAD phosphorylation in CSC. Furthermore, the frequency and self-renewal capacity of CSC was significantly reduced by knocking down the BAD expression. Consistent with our in vitro results, significant phosphorylation of BAD was found in CD44⁺ CSC of 83% breast tumor specimens. In addition, we also identified a positive correlation between BAD expression and disease stage in prostate cancer, suggesting a role of BAD in tumor advancement. Our studies unveil the role of BAD in the survival and self-renewal of CSC and propose BAD not only as an attractive target for cancer therapy but also as a marker of tumor progression.Although tumors initially respond positively to anti-cancer agents, several cancers, despite the best care and significant improvements in treatment, recur and progress to advanced stages of the disease. The mechanisms underlying this recurrence and metastasis are not clearly understood. Over the past decade, substantial evidence supported the cancer stem cell (CSC) hypothesis as a viable explanation for the initiation, progression and recurrence of cancer. According to this hypothesis, each tumor harbors a small subpopulation of specialized cells among cellular heterogeneity, known as CSC. These cells exhibit self-renewal property that drives tumorigenesis and plasticity to differentiate into multiple cell types contributing to tumor cellular heterogeneity. Support for this hypothesis came from the studies by Lapidot et al. who identified tumor-initiating cells in acute myeloid leukemia.^{1, 2} Subsequently, CSCs have been identified in several cancers.^{3, 4, 5, 6, 7, 8, 9, 10}Accumulating evidence suggests that current cancer therapies can only shrink tumors as they target and kill the differentiated cancer (DC) cells, but are unable to target the rare CSC population.^{11, 12} Thus, despite a wealth of information on DC cells, the active survival and self-renewal pathways in CSCs have not been characterized thoroughly. An understanding of the molecular mechanisms involved in the survival, self-renewal and resistance of CSCs to current therapeutic regimens is of immense clinical interest. This information will help in developing novel strategies for more effective treatments for cancer.Most anti-cancer drugs exert their effects through triggering the apoptotic pathways. However, malignant cancer cells can escape apoptosis by altering the expression level of proapoptotic and antiapoptotic BCL-2 family members. Considering the potential role of BCL-2 family members in tumorigenesis and cancer cell survival, their role in CSC biology has been increasingly studied.^{13, 14} BAD (BCL2-antagonist of cell death) is a member of the BH3-only BCL-2 family protein that when dephosphorylated promotes apoptosis by heterodimerizing with the antiapoptotic proteins BCL-XL and BCL-2.¹⁵ The cytotoxic effects of BAD are controlled by mechanisms that regulate its phosphorylation on at least two distinct serine residues, S112 and S136.^{16, 17, 18} Previously, we showed that phosphorylation at either site is sufficient to protect prostate cancer cells from apoptosis.^{19, 20, 21} We also showed that BAD promotes prostate tumor growth in mouse models.²² Clinically, while BAD expression was associated with relapse in tamoxifen-treated breast cancer patients,^{23, 24} phospho-BAD expression was associated with cisplatin resistance and poor overall survival in ovarian cancer.²⁵Our previous findings along with other reports showing the role of BAD in the apoptosis modulation and growth of DC cells^{19, 22, 26} prompted us to explore the potential role of BAD in the biology of CSCs. We started our investigation by assessing the role of BAD in survival and self-renewal of CSCs. As we observed a significant role for BAD in CSC''s biology, we extended our work to assess the BAD phosphorylation in CSCs of breast cancer patient tumors and for a potential correlation between BAD expression and disease progression in prostate cancer.