Goat Anti-Human RPA2 Polyclonal Antibody

Purpose: The WEE1 tyrosine kinase regulates G(2)-M transition and maintains genomic stability, particularly in p53-deficient tumors which require DNA repair after genotoxic therapy. Thus, a need arises to exploit the role of WEE1 inhibition in head and neck squamous cell carcinoma (HNSCC) mostly driven by tumor-suppressor loss. This completed phase I clinical trial represents the first published clinical experience using the WEE1 inhibitor, AZD1775, with cisplatin and docetaxel. Patients and Methods: We implemented an open-label phase I clinical trial using a 3+3 dose-escalation design for patients with stage III/IVB HNSCC with borderline-resectable or -unresectable disease, but who were candidates for definitive chemoradiation. Escalating AZD1775 was administered orally twice a day over 2.5 days on the first week, then in combination with fixed cisplatin (25 mg/m(2)) and docetaxel (35 mg/m(2)) for 3 additional weeks. The primary outcome measure was adverse events to establish MTD. Secondary measures included response rates, pharmacokinetics (PK), pharmacodynamics, and genomic data. Results: The MTD for AZD1775 was established at 150 mg orally twice per day for 2.5 days. RECISTv1.1 responses were seen in 5 of 10 patients; histologic adjustment revealed three additional responders. The only drug-limiting toxicity was grade 3 diarrhea. The PK C8hr target of 240 nmol/L was achieved on day 4 at all three doses tested. Pharmacodynamic analysis revealed a reduction in pY15-Cdk, and increases in gamma H2AX, CC3, and RPA32/RPA2 were noted in responders versus nonresponders. Conclusions: The triplet combination of AZD1775, cisplatin, and docetaxel is safe and tolerable. Preliminary results show promising antitumor efficacy in advanced HNSCC, meriting further investigation at the recommended phase II dose. (C) 2018 AACR.

Cells have evolved DNA damage response (DDR) to repair DNA lesions and thus preserving genomic stability and impeding carcinogenesis. DNA damage induction is accompanied by transient transcription repression. Here, we describe a previously unrecognized role of chromodomain Y-like (CDYL1) protein in fortifying double-strand break (DSB)-induced transcription repression and repair. We showed that CDYL1 is rapidly recruited to damaged euchromatic regions in a poly (ADP-ribose) polymerase 1 (PARP1)dependent, but ataxia telangiectasia mutated (ATM)-independent, manner. While the C-terminal region, containing the enoyl-CoA hydratase like (ECH) domain, of CDYL1 binds to poly (ADP-ribose) (PAR) moieties and mediates CDYL1 accumulation at DNA damage sites, the chromodomain and histone H3 trimethylated on lysine 9 (H3K9me3) mark are dispensable for its recruitment. Furthermore, CDYL1 promotes the recruitment of enhancer of zeste homolog 2 (EZH2), stimulates local increase of the repressive methyl mark H3K27me3, and promotes transcription silencing at DSB sites. In addition, following DNA damage induction, CDYL1 depletion causes persistent G2/M arrest and alters H2AX and replication protein A (RPA2) phosphorylation. Remarkably, the ` traffic-light reporter' system revealed that CDYL1 mainly promotes homology-directed repair (HDR) of DSBs in vivo. Consequently, CDYL1-knockout cells display synthetic lethality with the chemotherapeutic agent, cisplatin. Altogether, our findings identify CDYL1 as a new component of the DDR and suggest that the HDR-defective ` BRCAness' phenotype of CDYL1deficient cells could be exploited for eradicating cancer cells harboring CDYL1 mutations.