A High-throughput Screening of a Chemical Compound Library in Ovarian Cancer Stem Cells.

BACKGROUND: Epithelial ovarian cancer has a poor prognosis, mostly due to its late diagnosis and the development of drug resistance after a first platinum-based regimen. The presence of a specific population of "cancer stem cells" could be responsible of the relapse of the tumor and the development of resistance to therapy. For this reason, it would be important to specifically target this subpopulation of tumor cells in order to increase the response to therapy. METHOD: We screened a chemical compound library assembled during the COST CM1106 action to search for compound classes active in targeting ovarian stem cells. We here report the results of the high-throughput screening assay in two ovarian cancer stem cells and the differentiated cells derived from them. RESULTS AND CONCLUSION: Interestingly, there were compounds active only on stem cells, only on differentiated cells, and compounds active on both cell populations. Even if these data need to be validated in ad hoc dose response cytotoxic experiments, the ongoing analysis of the compound structures will open up to mechanistic drug studies to select compounds able to improve the prognosis of ovarian cancer patients.

In vitro cytotoxic activity of novel protoflavone analogs - selectivity towards a multidrug resistant cancer cell line.

BACKGROUND: Protoapigenone (PA), a natural flavonoid possessing an unusual p-quinol moiety on its B ring, is a prospective novel lead compound against cancer currently in development, together with WYC0209, a potent synthetic PA analog. Structure activity relationships (SAR) concerning different 1'-O-alkyl side-chains were also studied on two sets of derivatives. MATERIALS AND METHODS: Fifteen 1'-O-alkyl protoflavone derivatives were synthesized from genkwanin or 4'-hydroxy-6-methylflavone, thirteen of which are new compounds. All compounds were tested for their cytotoxic effect on four human cancer cell lines, such as HepG2 and Hep3B (hepatic), A549 (lung) and MDA-MB-231 (breast) cell lines, with doxorubicin as a positive control. All compounds, as well as PA, WYC0209 and fourteen of their previously reported analogs were also tested on a multidrug-resistant (MDR) sub-cell line of L5178 mouse T-cell lymphoma and on its parental counterpart (PAR). RESULTS: In general, derivatives bearing a free hydroxyl group at C-1' exerted the strongest activities, while C-1'-substituted compounds were found to be much weaker. Derivatives of 6-methylflavone exhibited mild, but statistically significant selectivity towards the MDR cell line. CONCLUSION: The results are in agreement with our previous findings for fundamental SAR of protoflavones. 6-Methylated protoflavones may serve as valuable leads for developing selective compounds against MDR cancer. Identical activity of other derivatives on the PAR and MDR cell lines suggests that cancer cells cannot exhibit resistance to protoflavones by ABCB1 efflux pump overexpression.

Rapid, laser-induced conversion of 20-hydroxyecdysone and its diacetonide -- experimental set-up of a system for photochemical transformation of bioactive substances.

BACKGROUND: Photochemical transformation of certain bioactive compounds for the purpose of obtaining derivatives with increased bioactivity is a prospective area of synthetic chemistry. Ecdysteroids, analogs of the insect molting hormone, which can also exert several beneficial effects in mammals including humans, contain an enone moiety in their B ring, and, as such, are good candidates for photochemical transformations. MATERIALS AND METHODS: 20-hydroxyecdysone (20E), the most common ecdysteroid in Nature, and the easily obtained derivative 20-hydroxyecdysone 2,3;20,22-diacetonide (20ED), at different concentrations, were exposed to a 266 nm laser beam at an energy level of 6.5 mJ for different periods of time and evaluated for fluorescence emission during the process of irradiation. The products of irradiation were scanned from 200 to 1500 nm and then subjected to one-dimensional and two-dimensional thin layer chromatography. RESULTS: During irradiation, progressive significant changes in the fluorescence emission spectra were noted for both compounds with time that were accompanied by changes in their UV-Vis spectra. Full conversion of both compounds was reached within 14 minutes, and both compounds yielded several major products and several minor ones representing a wide polarity range. CONCLUSION: The photo-transformation system described here was proven to be a useful and flexibly adjustable tool for the laser-catalyzed conversion of bioactive compounds. Due to the multi-drug resistance reversal activity of the less polar ecdysteroids, several new products are promising for being tested against various cancer cell lines. Fractionation, isolation and characterization of the irradiated products are currently in process.

A novel member of the WD-repeat gene family, WDR11, maps to the 10q26 region and is disrupted by a chromosome translocation in human glioblastoma cells.

Allelic deletions of 10q25-26 and 19q13.3-13.4 are the most common genetic alterations in glial tumors. We have identified a balanced t(10;19) reciprocal translocation in the A172 glioblastoma cell line which involves both critical regions on chromosomes 10 and 19. In addition, loss of an entire copy of chromosome 10 has occurred in this cell line suggesting that the translocation event may provide a highly specific critical inactivating event in a gene responsible for tumorigenesis. Positional cloning of this translocation breakpoint resulted in the identification of a novel chromosome 10 gene, WDR11, which is a member of the WD-repeat gene family. The WDR11 gene is ubiquitously expressed, including normal brain and glial tumors. WDR11 is composed of 29 exons distributed over 58 kilobases and oriented towards the telomere. The translocation resulted in deletion of exon 5 and consequently fusion of intron 4 of WDR11 to the 3' untranslated region of a novel member, ZNF320, of the Krüppel-like zinc finger gene family. Since ZNF320 is oriented toward the centromere of chromosome 19, both genes appeared on the same derivative chromosome der(10). The chimeric transcript encodes the WDR11 polypeptide, which is truncated after the second of six WD-repeats. ZNF320 is also expressed in A172 cells, although it is not clear if the translocation affects the expression of the altered gene because of the presence of another unrearranged gene on chromosome 19. We suggest that, because of its localization in a region frequently showing LOH and the observation of inactivation of this gene in glioblastoma cells, WDR11 is a candidate gene for the frequently proposed tumor suppressor gene in 10q25-26 which is involved in tumorigenesis of glial and other tumors showing frequent alterations in the distal 10q region.