ME0328

ME0328 is a potent and selective inhibitor of PARP with IC50 value of 0.89 and 6.3 μM for PARP3 and PARP1, respectively [1].

Poly (ADP-ribose) polymerase (PARP) is a family of proteins mainly involved in programmed cell death and DNA repair. The overactivation of PARP may reduce the stores of cellular NAD+ and induce ATP depletion and cell death.

ME0328 is a potent and selective PARP inhibitor. ME0328 selectively inhibited ADP-ribosyltransferase-3/poly(ADP-ribose) polymerase-3 (ARTD3) with IC50 value of 0.89 μM and inhibited ARTD1 and ARTD2 with IC50 values of 6.3 and 10.8 μM, respectively. In human alveolar basal epithelial (A549) cells, treatment with ME0355 (10 μM) followed by γ-irradiation significantly delayed γH2AX-foci resolution in a concentration-dependent way, which suggested that ME0328 inhibited ARTD3 in cells. In nonirradiated human A549 and mouse MRC5 cells, ME0328 (10 μM) did not exhibit toxicity [1].

Reference:
[1].  Lindgren AE, Karlberg T, Thorsell AG, et al. PARP inhibitor with selectivity toward ADP-ribosyltransferase ARTD3/PARP3. ACS Chem Biol, 2013, 8(8): 1698-1703.

PARP inhibitor with selectivity toward ADP-ribosyltransferase ARTD3/PARP3.[Pubmed:23742272]

ACS Chem Biol. 2013 Aug 16;8(8):1698-703.

Inhibiting ADP-ribosyl transferases with PARP-inhibitors is considered a promising strategy for the treatment of many cancers and ischemia, but most of the cellular targets are poorly characterized. Here, we describe an inhibitor of ADP-ribosyltransferase-3/poly(ADP-ribose) polymerase-3 (ARTD3), a regulator of DNA repair and mitotic progression. In vitro profiling against 12 members of the enzyme family suggests selectivity for ARTD3, and crystal structures illustrate the molecular basis for inhibitor selectivity. The compound is active in cells, where it elicits ARTD3-specific effects at submicromolar concentration. Our results show that by targeting the nicotinamide binding site, selective inhibition can be achieved among the closest relatives of the validated clinical target, ADP-ribosyltransferase-1/poly(ADP-ribose) polymerase-1.

CRISPR-mediated targeting of HER2 inhibits cell proliferation through a dominant negative mutation.[Pubmed:27815036]

Cancer Lett. 2017 Jan 28;385:137-143.

With the discovery of the CRISPR/Cas9 technology, genome editing could be performed in a rapid, precise and effective manner. Its potential applications in functional interrogation of cancer-causing genes and cancer therapy have been extensively explored. In this study, we demonstrated the use of the CRISPR/Cas9 system to directly target the oncogene HER2. Directing Cas9 to exons of the HER2 gene inhibited cell growth in breast cancer cell lines that harbor amplification of the HER2 locus. The inhibitory effect was potentiated with the addition of PARP inhibitors. Unexpectedly, CRISPR-induced mutations did not significantly affect the level of HER2 protein expression. Instead, CRISPR targeting appeared to exert its effect through a dominant negative mutation. This HER2 mutant interfered with the MAPK/ERK axis of HER2 downstream signaling. Our work provides a novel mechanism underlying the anti-cancer effects of HER2-targeting by CRISPR/Cas9, which is distinct from the clinical drug Herceptin. In addition, it opens up the possibility that incomplete CRISPR targeting of certain oncogenes could still have therapeutic value by generation of dominant negative mutants.