Showing papers by "Thomas D. Schmittgen published in 2011"

miR-221 silencing blocks hepatocellular carcinoma and promotes survival

Abstract: Patients with advanced hepatocellular carcinoma (HCC) face a dismal prognosis because of a lack of any effective therapies. To address this situation, we conducted a preclinical investigation of the therapeutic efficacy of oligonucleotides directed against the oncogenic microRNA miR-221, which has been implicated in HCC. Of 9 chemistries evaluated, we determined that a 2'-O-methyl phosphorothioate-modified anti-miR-221 oligonucleotide was most effective at reducing proliferation in vitro. A cholesterol-modified isoform of anti-miR-221 (chol-anti-miR-221) exhibited improved pharmacokinetics and liver tissue distribution compared with unmodified oligonucleotide. Chol-anti-miR-221 significantly reduced miR-221 levels in liver within a week of intravenous administration and in situ hybridization studies confirmed accumulation of the oligonucleotide in tumor cells in vivo. Within the same period, chol-anti-miR-221 reduced tumor cell proliferation and increased markers of apoptosis and cell-cycle arrest, elevating the tumor doubling time and increasing mouse survival. Taken together, our findings offer a preclinical proof of efficacy for chol-anti-miR-221 in a valid orthotopic mouse model of HCC, suggesting that this targeted agent could benefit treatment for patients with advanced HCC.

microRNA Replacement Therapy for Cancer

Abstract: microRNA are small noncoding RNAs that translationally repress their target messenger RNAs. Many microRNAs are expressed at reduced levels in tumors. microRNAs with reduced expression in cancer often regulate oncogenes, resulting in enhanced tumor growth. One therapeutic option is to restore microRNA levels in the tumor to that of the non-diseased tissue. This is possible by delivering microRNA to the tumor in the form of an oligonucleotide mimic or by expressing the microRNA in the cancer using a gene vector. This article surveys the field of oligonucleotide mimics and gene vector approaches to restore microRNA levels in tumors and reviews the literature on experimental and pre-clinical studies that have used these approaches to treat cancer.

Abstract 1183: miR-199a-3p targets CD44 and reduces proliferation of CD44 positive hepatocellular carcinoma cell lines

Abstract: Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Previous work by us and others reported decreased expression of miR-199a-3p in hepatocellular carcinoma (HCC) tissues compared to adjacent benign tissue. We report here a significant reduction of miR-199a-3p expression in 7 HCC cell lines (Huh7, HepG2, SNU182, PLC/PRF/5, Hep3B, SNU423 and SNU449) compared to primary hepatocytes. To determine if miR-199a-3p has a tumor suppressive role, miR-199a-3p mimetic was transfected into the 7 HCC cell lines. miR-199a-3p mimetic reduced cell proliferation by approximately 60% compared to control oligonucleotide in only two cell lines (SNU449 and SNU423); the proliferation of the other 5 treated cell lines was similar to control oligonucleotide. A miR-199a-3p mimetic formulated with chemical modifications to enhance stability while preserving processing reduced cell proliferation in SNU449 and SNU423 to the same extent as the commercially available miR-199a-3p mimetic. Furthermore, only the duplex miR-199a-3p mimetic, and not the guide strand alone, was effective at reducing cell viability. Since a CD44 variant was essential for c-Met signaling (Orian-Rousseau, et al., Genes Dev. 2002) and c-Met is a known miR-199a-3p target, we hypothesized that miR-199a-3p may also target CD44. Indeed, miRNA target algorithms predict miR-199a-3p to be a putative target of CD44. Immunoblotting confirmed that only the HCC lines that were sensitive to the effects of miR-199a-3p mimetic (SNU449 and SNU423) were CD44+. Direct targeting of CD44 by miR-199a-3p was confirmed using luciferase reporter assays and immunoblotting. Transfection of miR-199a-3p into SNU449 cells reduced in vitro invasion and sensitized the cells to doxorubicin; both effects were enhanced when hyaluronic acid was added to the cell cultures. An inverse correlation between the expression of miR-199a-3p and CD44 protein was noted in primary HCC tissue specimens. The anti-proliferative and anti-invasive properties of miR-199a-3p mimetic on CD44+ HCC may be a useful targeted therapy for CD44+ HCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1183. doi:10.1158/1538-7445.AM2011-1183