Page 65 - 2014 Printable Abstract Book
P. 65
syndrome. Importantly, nanomolar doses of these drugs produce growth inhibition of subpopulations of
breast cancer cells, effects that are accompanied by sustained decreases in genome-wide promoter DNA
methylation, gene re-expression, and antitumor changes in key cellular regulatory pathways. We have
applied this novel approach to breast cancer metastases also by using the next generation DNMT inhibitor
SGI-110, a nucleotide designed to obtain a more stable release of DAC in vivo. The second approach is
through the inhibition of EZH2 and Polycomb Repressor Complex (PRC) mediated gene silencing. The
demonstration that over expression of EZH2 leads to cancer invasion and progression indicates that it
serves as a clinical marker of aggressive breast cancer and shows promise as a therapeutic target based
on pre-clinical studies. Finally, combining inhibition of multiple epigenetic targets will likely be synergistic,
as has been demonstrated for DNA methylation and histone deacetylation. Inhibitors of EZH2, such as
GSK126 for example. For this purpose we have used four different approaches: 1- reversal of DNA
hypermethylation and associated gene silencing through the use of the DNMT inhibitors 5-azacytidine
(azacitidine) and 5-aza-2′-deoxycytidine (DAC, decitabine). In Approach 2 we have used ext generation
DNMT inhibitor SGI-110, a nucleotide designed for obtaining a more stable release of DAC in vivo. In the
approach 3 we have use inhibitors of EZH2 and PRC mediated gene silencing using GSK126 an inhibitor of
EZH2 ]; and lastly, for approach four we have combined inhibition of multiple epigenetic targets that will
likely be synergistic, as demonstrated for DNA methylation and histone deacetylation [21-23]. The
tumorigenic ability of the control and treated cells has been tested in 45 day old female SCID mice utilizing
procedures that are standard at the FCCC laboratories. We decided to use experimental metastasis model.
For the metastatic assay the cells under study (trMCF, bsMCF, MCF7 and MDA-MB231) that have been
transfected utilizing Lipofectamine/Plus Reagent from Life Technologies. Our results revealed that the
DNMT inhibitor SGI is the best drug to reverse EMT by inhibiting cell motility, invasion and colony
formation in agar methocel, as well as promoting cell differentiation by increasing the expression of E-
cadherin, down regulation of vimentin and SLUG. The results suggest that this new generation of DNMT
inhibitor is superior to previous DNMT and the HDAC inhibitors tested. (This work was supported by The
Pennsylvania Cancer Cure Grant 6914101 and by NIH core grant CA06927 to Fox Chase Cancer Center. The
compound SGI-110 was provided by Astex Pharmaceutical, Inc. Dublin CA).
(S1502) A counter-intuitive role for apoptotic caspases in facilitating radiation induced carcinogenesis.
Chuan-Yuan Li, Duke University Medical Center, Durham, NC
Caspases are in general thought of as killer enzymes that are barriers for mutagenesis and carcinogenesis.
However, our recent work suggests that caspases may play some unexpected roles in mutagenesis and
carcinogenesis. We conducted a series of experiments to examine the effect of caspases in radiation
induced mutagenesis and carcinogenesis. Our results show mammalian cells can survive caspase 3
activation and among the survivors capase 3 &7 promotes rather than inhibits genetic instability and
carcinogenesis. Blocking caspases 3 significantly reduced space radiation induced anchorage independent
growth in human mammary epithelial cells. Furthermore, radiation induced genetic instability and
chemical carcinogenesis was significantly attenuated in mice with caspase 3 deficiency. Because caspase
3 could be induced by a wide variety of environmental stressors, our discovery may have broad
implications for the involvement of apoptotic factors in mammalian mutagenesis and carcinogenesis.
63 | P a g e
breast cancer cells, effects that are accompanied by sustained decreases in genome-wide promoter DNA
methylation, gene re-expression, and antitumor changes in key cellular regulatory pathways. We have
applied this novel approach to breast cancer metastases also by using the next generation DNMT inhibitor
SGI-110, a nucleotide designed to obtain a more stable release of DAC in vivo. The second approach is
through the inhibition of EZH2 and Polycomb Repressor Complex (PRC) mediated gene silencing. The
demonstration that over expression of EZH2 leads to cancer invasion and progression indicates that it
serves as a clinical marker of aggressive breast cancer and shows promise as a therapeutic target based
on pre-clinical studies. Finally, combining inhibition of multiple epigenetic targets will likely be synergistic,
as has been demonstrated for DNA methylation and histone deacetylation. Inhibitors of EZH2, such as
GSK126 for example. For this purpose we have used four different approaches: 1- reversal of DNA
hypermethylation and associated gene silencing through the use of the DNMT inhibitors 5-azacytidine
(azacitidine) and 5-aza-2′-deoxycytidine (DAC, decitabine). In Approach 2 we have used ext generation
DNMT inhibitor SGI-110, a nucleotide designed for obtaining a more stable release of DAC in vivo. In the
approach 3 we have use inhibitors of EZH2 and PRC mediated gene silencing using GSK126 an inhibitor of
EZH2 ]; and lastly, for approach four we have combined inhibition of multiple epigenetic targets that will
likely be synergistic, as demonstrated for DNA methylation and histone deacetylation [21-23]. The
tumorigenic ability of the control and treated cells has been tested in 45 day old female SCID mice utilizing
procedures that are standard at the FCCC laboratories. We decided to use experimental metastasis model.
For the metastatic assay the cells under study (trMCF, bsMCF, MCF7 and MDA-MB231) that have been
transfected utilizing Lipofectamine/Plus Reagent from Life Technologies. Our results revealed that the
DNMT inhibitor SGI is the best drug to reverse EMT by inhibiting cell motility, invasion and colony
formation in agar methocel, as well as promoting cell differentiation by increasing the expression of E-
cadherin, down regulation of vimentin and SLUG. The results suggest that this new generation of DNMT
inhibitor is superior to previous DNMT and the HDAC inhibitors tested. (This work was supported by The
Pennsylvania Cancer Cure Grant 6914101 and by NIH core grant CA06927 to Fox Chase Cancer Center. The
compound SGI-110 was provided by Astex Pharmaceutical, Inc. Dublin CA).
(S1502) A counter-intuitive role for apoptotic caspases in facilitating radiation induced carcinogenesis.
Chuan-Yuan Li, Duke University Medical Center, Durham, NC
Caspases are in general thought of as killer enzymes that are barriers for mutagenesis and carcinogenesis.
However, our recent work suggests that caspases may play some unexpected roles in mutagenesis and
carcinogenesis. We conducted a series of experiments to examine the effect of caspases in radiation
induced mutagenesis and carcinogenesis. Our results show mammalian cells can survive caspase 3
activation and among the survivors capase 3 &7 promotes rather than inhibits genetic instability and
carcinogenesis. Blocking caspases 3 significantly reduced space radiation induced anchorage independent
growth in human mammary epithelial cells. Furthermore, radiation induced genetic instability and
chemical carcinogenesis was significantly attenuated in mice with caspase 3 deficiency. Because caspase
3 could be induced by a wide variety of environmental stressors, our discovery may have broad
implications for the involvement of apoptotic factors in mammalian mutagenesis and carcinogenesis.
63 | P a g e
