Abstract 3722
Background
Histone acetylation plays an important role in regulating the chromatin structure and is tightly regulated by histone acetyltransferases (HAT) and histone deacetylases (HDAC). Recent studies have demonstrated that several chromatin-regulating proteins can modulate cellular responses to other cytotoxic modalities including ionizing radiation and chemotherapeutic drugs. Even though histone acetylation is one of the key mechanisms of epigenetic regulation, relatively little is known about the cancer therapeutic potential of HAT inhibitors. This is in stark contrast to the well-studied effects of HDAC inhibitors. In this study, we investigated the proton beam-sensitizing effect of C646, a selective small molecule inhibitor of p300 histone acetyltransferase in human pancreatic cancer cells.
Methods
Cell viability assay (CCK-8; Dojindo), Clonogenic survival assay, Cell cycle analysis (PI staining). Annexin V-FITC and PI staining, γ-H2AX foci, Western blot, BxPC-3 Xenograft tumor model, TUNEL assay.
Results
AsPC-1, BxPC-3 and Mia-paca2 cells exhibited increase in radiosensitivity when exposed to C646 at all doses of proton beam tested. C646 pre-treatment induce led to increase of sub-G1 population and abolishment of G2/M arrest. Flow cytometry analysis with annexin V staining and Western blot analysis showed that The pre-treatment with C646 significantly enhanced proton-induced apoptotic cell death through the down-regulation of anti-apoptotic molecules. Our in vivo results demonstrate synergistic effects of combination therapy with C646 and proton beam. In BxPC-3 xenograft tumor model, C646 pre-treatment increased proton-induced tumor growth inhibition and apoptotic cell death in tumor tissues. In addition, the combination treatment of C646 with proton beam increased DNA damage and decreased activation of DNA repair pathway compared with proton alone.
Conclusions
Our results suggest that the C646 may increase proton- induced apoptosis through the modulation of various pro- and anti- apoptotic molecules in human pancreatic cancer cells. These results provide proof of principle that the inhibition of histone acetylation by HATis can be exploited to develop new proton-sensitizer.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
National Research Foundation of Korea (NRF).
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
3157 - Efficacy and safety of anlotinib in advanced leiomyosarcoma: Subgroup analysis of a phase IIB trial (ALTER0203)
Presenter: Yihebali Chi
Session: Poster Display session 1
Resources:
Abstract
3710 - The effect of treatment line on the efficacy of Anlotinib hydrochloride in advanced alveolar soft part sarcoma patients
Presenter: Zhiwei Fang
Session: Poster Display session 1
Resources:
Abstract
3184 - Prior exposure to pazopanib (PAZ) did not minor efficacy of regorafenib (REG) in non-adipocytic soft tissue sarcoma patients (pts)
Presenter: Nicolas Penel
Session: Poster Display session 1
Resources:
Abstract
798 - Pexidartinib (Pex) for locally advanced tenosynovial giant cell tumor (TGCT): characterization of hepatic adverse reactions (ARs)
Presenter: Sebastian Bauer
Session: Poster Display session 1
Resources:
Abstract
6117 - VEGFR2 and ITGA polymorphisms as novel pan-sarcoma biomarkers for sensitivity prediction as well as toxicity prevention anti-angiogenesis therapy in pediatric and young adult
Presenter: Qiyuan Bao
Session: Poster Display session 1
Resources:
Abstract
5450 - Reversion of resistance to mTOR inhibitors with the addition of exemestane in patients with malignant PEComa.
Presenter: Roberta Sanfilippo
Session: Poster Display session 1
Resources:
Abstract
4279 - Efficacy and Safety of VEGFR2 Inhibitor Apatinib combined with chemotherapy for Sarcoma in Stage IV
Presenter: Zhiwu Ren
Session: Poster Display session 1
Resources:
Abstract
5929 - Outcomes of metastatic soft tissue sarcoma treated with Pazopanib from dedicated medical oncology sarcoma clinic: A holistic care approach from a developing country
Presenter: Akhil Kapoor
Session: Poster Display session 1
Resources:
Abstract
2469 - Inhibition of mTOR signaling enhances Trabectedin activity in Soft Tissue Sarcoma
Presenter: David Moura
Session: Poster Display session 1
Resources:
Abstract
4210 - Efficacy and safety of apatinib for advanced gastrointestinal stromal tumors after failure of imatinib and sunitinib: An open-label, multicenter, single-arm, phase II trial
Presenter: Zhaolun Cai
Session: Poster Display session 1
Resources:
Abstract