Post-Transcriptional Regulation of the GASC1 Oncogene with Active Tumor-Targeted siRNA-Nanoparticles

GASC1 promotes glioma progression by enhancing NOTCH1 signaling

Recent studies have reported that gene amplified in squamous cell carcinoma 1 (GASC1) is involved in the progression of several types of cancer. However, whether GASC1 promotes glioma progression remains unknown. Therefore, the present study aimed to investigate the effect of GASC1 exposure on glioma tumorigenesis. The western blot demonstrated that grade III and IV glioma tissues exhibited a higher mRNA and protein expression of GASC1. Moreover, CD133+ U87 or U251 cells from magnetic cell separation exhibited a higher GASC1 expression. Invasion Transwell assay, clonogenic assay and wound healing assay have shown that GASC1 inhibition using a pharmacological inhibitor and specific short hairpin (sh)RNA suppressed the invasive, migratory and tumorsphere forming abilities of primary culture human glioma cells. Furthermore, GASC1‑knockdown decreased notch receptor (Notch) responsive protein hes family bHLH transcription factor 1 (Hes1) signaling. GASC1 inhibition reduced notch receptor 1 (NOTCH1) expression, and a NOTCH1 inhibitor enhanced the effects of GASC1 inhibition on the CD133+ U87 or U251 cell tumorsphere forming ability, while NOTCH1 overexpression abrogated these effects. In addition, the GASC1 inhibitor caffeic acid and/or the NOTCH1 inhibitor DAPT (a γ‑Secretase Inhibitor), efficiently suppressed the human glioma xenograft tumors. Thus, the present results demonstrated the importance of GASC1 in the progression of glioma and identified that GASC1 promotes glioma progression, at least in part, by enhancing NOTCH signaling, suggesting that GASC1/NOTCH1 signaling may be a potential therapeutic target for glioma treatment.

A Method for Targeted Nonviral siRNA Delivery in Cancer and Inflammatory Diseases

Small interfering RNA (siRNA)-based therapy has been subject of intense research since the discovery of RNA interference (RNAi), providing a tool to potentially silence any chosen gene. Nevertheless, efficient delivery still presents a major hurdle to translating this promising technology into medical practice. Here, we describe a straightforward method to prepare and characterize an effective delivery system consisting of low-molecular-weight polyethylenimine (PEI) and transferrin (Tf). Tf-PEI polyplexes are not only able to successfully transport and protect the sensitive nucleic acid payload from degradation but also to selectively deliver the siRNA to transferrin receptor (TfR)-overexpressing cells, playing key roles in the pathology of numerous cancer types as well as inflammatory diseases.

The JmjN domain as a dimerization interface and a targeted inhibitor of KDM4 demethylase activity

Histone methylation is regulated to shape the epigenome by modulating DNA compaction, thus playing central roles in fundamental chromatin-based processes including transcriptional regulation, DNA repair and cell proliferation. Histone methylation is erased by demethylases including the well-established KDM4 subfamily members, however, little is known about their dimerization capacity and its impact on their demethylase activity. Using the powerful bimolecular fluorescence complementation technique, we herein show the in situ formation of human KDM4A and KDM4C homodimers and heterodimers in nuclei of live transfectant cells and evaluate their H3K9me3 demethylation activity. Using size exclusion HPLC as well as Western blot analysis, we show that endogenous KDM4C undergoes dimerization under physiological conditions. Importantly, we identify the JmjN domain as the KDM4C dimerization interface and pin-point specific charged residues therein to be essential for this dimerization. We further demonstrate that KDM4A/C dimerization is absolutely required for their demethylase activity which was abolished by the expression of free JmjN peptides. In contrast, KDM4B does not dimerize and functions as a monomer, and hence was not affected by free JmjN expression. KDM4 proteins are overexpressed in numerous malignancies and their pharmacological inhibition or depletion in cancer cells was shown to impair tumor cell proliferation, invasion and metastasis. Thus, the KDM4 dimer-interactome emerging from the present study bears potential implications for cancer therapeutics via selective inhibition of KDM4A/C demethylase activity using JmjN-based peptidomimetics.

Targeted Delivery of siRNA to Transferrin Receptor Overexpressing Tumor Cells via Peptide Modified Polyethylenimine

The use of small interference RNA (siRNA) to target oncogenes is a promising treatment approach for cancer. However, siRNA cancer therapies are hindered by poor delivery of siRNA to cancer cells. Transferrin receptor (TfR) is overexpressed in many types of tumor cells and therefore is a potential target for the selective delivery of siRNA to cancer cells. Here, we used the TfR binding peptide HAIYPRH (HAI peptide) conjugated to cationic polymer branched polyethylenimine (bPEI), optimized the coupling strategy, and the TfR selective delivery of siRNA was evaluated in cells with high (H1299) and low TfR expression (A549 and H460). The HAI-bPEI conjugate exhibited chemico-physical properties in terms of size, zeta-potential, and siRNA condensation efficiency similar to unmodified bPEI. Confocal microscopy and flow cytometry results revealed that HAI-bPEI selectively delivered siRNA to H1299 cells compared with A549 or H460 cells. Moreover, HAI-bPEI achieved more efficient glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene knockdown in H1299 cells compared with bPEI alone. However, despite optimization of the targeting peptide and coupling strategy, HAI-bPEI can only silence reporter gene enhanced green fluorescent protein (eGFP) at the protein level when chloroquine is present, indicating that further optimization of the conjugate is required. In conclusion, the HAI peptide may be useful to target TfR overexpressing tumors in targeted gene and siRNA delivery approaches.