Abstract 2741: Synergistic inhibition of tumor growth and overcoming chemo-resistance by simultaneously targeting key components in DNA damage/repair, epigenetic, and putative cancer stem cell signaling pathways using novel dual-functional DNA-alkylating/HDAC inhibitor and tumor suppressor gene nanoparticles in lung cancer

In this study we explored a novel therapeutic strategy aimed to simultaneously target multiple key components in DNA damage/repair, epigenetic, and putative cancer stem cell (CSC) signaling pathways using a novel dual-target DNA-alkylating nitrogen mustard/HDAC inhibitor (DANM/HDACi) and tumor suppressor gene (TSG) nanoparticles to promote antitumor synergy and overcome drug resistance in lung cancer. We evaluated therapeutic effects of a new class DNAM/HDACi, NL10, as a single agent or in combination with novel TSGs NPRL2, a regulator of the DNA damage checkpoint pathway, and p53, a regulator of apoptosis and drug resistance in the DNA damage/repair pathway in more than 50 human NSCLC and SCLC cell lines. We detected a high anti-tumor potency by NL101 treatment across lung cancer cell lines, with IC 50 doses ranging from nanomolar to lower micromolar levels. A 20 to 100-fold higher level of cytotoxicity was observed across these cell lines, particularly in SCLC cell lines, treated by NL101 than in those treated by bendamustine, a nitrogen mustard that is currently in Phase II/III clinical trials in SCLC patients. We analyzed the NL101-induced DNA damage in NSCLC H1299 cells and found that NL101 induced a significantly higher degree of DNA damage than that induced by either bendamustine or cisplatin at the same IC 20 dose level for each agent. We analyzed the DNA-damage-induced apoptosis in NSCLC cells treated by NL101 alone or in combination with DOTAP:Cholesterol (DC)-complexed NPRL2- or p53-expressing plasmid DNA nanoparticles. We detected a significantly enhanced apoptosis in both combination treatments with NL101+DC-NPRL2 and NL101+DC-p53. We also found that combination treatment with NL101 and DC-NPRL2 nanoparticles promoted a synergistic inhibitory effect on tumor cell-induced clonogenecity in H1299 cells and on tumor cell growth in SCLC H69 and GLC16 cells at effective dose levels of NL101 from IC 10 to IC 75 . Furthermore, we found that the sensitivity of lung cancer cells to NL101 treatment showed a significantly negative correlation with expression levels of the HDAC family proteins HDAC1, HDAC2, HDAC3, and HDAC5 and the putative lung cancer stem cell (CSC) marker ALDH1 protein. We found a dose-dependent inhibition of multiple HDACs and CSC markers in both NSCLC and SCLC cells. Our results suggest that a combination treatment using a novel DANM/HDACi with pro-apoptotic TSGs targeting the DNA damage/repair, epigenetic, and CSC signaling pathways will enhance chemotherapeutic sensitivity, promote anti-cancer synergism, overcome drug resistance, and block tumor progression and relapse by targeting putative CSCs. (Supported by grants P50CA70907, RO1 CA-116322, and W81XWH0920139) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2741. doi:1538-7445.AM2012-2741