新穎組蛋白去乙醯酶抑制劑－HTPB及三足樹枝狀HTPB分子覆蓋硒化鎘/硫化鋅奈米粒子(Nano-HTPB)於肺癌治療之應用

Abstract

Background: Overexpression and/or increased activity of histone deacetylases (HDACs) in hematologic and solid malignancies make HDACs a potential therapeutic target for cancer treatment. HDAC inhibitors have shown pleiotropic anticancer activities in hematological cancers. However, validated HDAC inhibitors for the treatment of solid tumors remain to be developed. Purpose: To develop novel HDAC inhibitors to treat solid tumor, the current study evaluated the antitumor effects of novel HDAC inhibitors, N-Hydroxy-4-(4- phenylbutyryl-amino) benzamide HTPB and its nanoparticle-conjugated derivative Nano-HTPB by in vitro and in vivo models of human lung cancer. Results: We found that Nano-HTPB delivered to cell nucleus at 6~48 hours in various lung cancer cell lines, indicating that HTPB conjugated with quantum dot nanoparticles was a feasible strategy for cancer cell delivery. In addition, Nano-HTPB and HTPB significantly induced cytotoxicity more potent than FDA-approved HDAC inhibitor SAHA in various lung cancer cells, without showing apparent cytotoxicity towards normal lung cells. Nano-HTPB was more potent than HTPB in IC50 values, which were in nM ranges. Nano-HTPB and HTPB induced G2/M arrest and led to apoptotic DNA ladder accompanied with induction of proapoptotic-related proteins and mitochondria-specific caspase-3/9 activities. The data from HDAC fluorometric activity assay suggested that Nano-HTPB and HTPB were pan-HDAC inhibitors, and they stimulated acetylation of histone and non-histone proteins in dose-dependent and time-dependent manners. In addition, Nano-HTPB and HTPB inhibited cancer cell migration at non-cytotoxic doses, which through inhibiting activity of matrix metalloproteinases, RhoA, and focal adhesion complex. Furthermore, the data from confocal microscopy analysis indicated that the polymerization of F-actin stress fiber was dramatically inhibited after Nano-HTPB or HTPB treatment. Finally, Nano-HTPB and HTPB efficiently inhibited tumor growth in xenograft animal models without significant side effects. In addition, HTPB significantly inhibited metastasis of 4T1-luc cells in vivo. Conclusions: Our findings suggest that Nano-HTPB and HTPB are potent HDAC inhibitors and have clinical value in lung cancer treatment because they inhibit tumor growth and cell migration. The in vivo anti-metastasis effect, in vivo metabolic effects, and pharmacokinetics of Nano-HTPB and HTPB are under investigation.