Epidermal growth factor receptor (ErbB1, EGFR) is overexpressed in a variety of human cancer cells. It has been considered as a rational target for drug delivery. To identify novel ligands with specific binding capabilities to EGFR, we screened a phage display peptide library and found an enriched phage clone encoding the amino acid sequence YHWYGYTPQNVI (designated as GE11). Competitive binding assay and Scatchard analysis revealed that GE11 peptide bound specifically and efficiently to EGFR with a dissociation constant of approximately 22 nM, but with much lower mitogenic activity than with EGF. We showed that the peptides were internalized preferentially into EGFR highly expressing cells, and they accumulated in EGFR overexpressing tumor xenografts after i.v. delivery in vivo. In gene delivery studies, GE11-conjugated polyethylenimine (PEI) vectors were less mitogenic, but still quite efficient at transfecting genes into EGFR highly expressing cells and tumor xenografts. Taken together, GE11 is a potentially safe and efficient targeting moiety for selective drug delivery systems mediated through EGFR.

Ligand or peptide-targeted phagemid particles are being pursued as vehicles for receptor-mediated gene delivery. Here we describe a helper phage in which the protein III (pIII) protein is modified by the addition of a ligand peptide sequence at the amino terminus. Phagemid particles can be prepared with the help of this modified helper phage and should display the ligand peptide in most of the pIII proteins on the phagemid surface. Using such a method, it is not necessary for the phagemid to encode the pIII protein, which leaves a larger space for cloning genes of interest. In addition, the technique should allow for the rapid testing of peptide ligands selected from phage display libraries using phagemids encoding various reporter genes (e.g., green fluorescent protein, luciferase, beta-galactosidase) and therapeutic genes.

Background/Aims: This study aimed to explore the effects of the long non-coding RNA HOST2 (lnc-HOST2) on the proliferation, migration, invasion and apoptosis of osteosarcoma cells. Methods: Osteosarcoma tissues and adjacent normal tissues from 52 patients were selected. Human osteosarcoma cell lines (SaOS2, HOS, U2OS and MG-63) were collected and cultured; MG-63 cells had the highest lnc-HOST2 expression and thus were used in subsequent experiments. Then, MG-63 cells were transfected and divided into the blank (no transfection), si-CON (transfected with negative control siRNA) and si-lnc-HOST2 (transfected with small interference lnc-HOST2 siRNA) groups. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to determine the expression of lnc-HOST2 in primary tissues and cells. Cell growth was detected using the CCK-8 and colony formation assays. Cell doubling time was detected. Cell migration and invasion were observed using the scratch test and Transwell assays. Cell apoptosis and cell cycle progression of osteosarcoma cells were detected using flow cytometry with annexin V/PI double staining and PI staining, respectively. Results: The level of lnc-HOST2 expression in the si-lnc-HOST2 group was significantly decreased compared to that in the blank and si-CON groups. The OD values in the si-lnc-HOST2 group were significantly lower than those in the blank and si-CON groups. Compared to the blank and si-CON groups, the si-lnc-HOST2 group presented significant decreases in the colony number and healing rates after scratching. The number of invasive cells in the si-lnc-HOST2 group was significantly less than that in the blank and si-CON groups. In the si-lnc-HOST2 group, the cell cycle was mainly halted in the G1 phase, and the apoptosis rate and doubling time in this group were significantly higher than those in the blank group and si-CON group. Conclusions: Inhibition of lnc-HOST2 could suppress the proliferation, migration, and invasion and promote the apoptosis of osteosarcoma cells.

miR-150 expression in osteosarcoma (OS) cell lines and human osteoblast cells was detected, and OS cell models were transfected with exogenous miR-150 to investigate its role in cell proliferation, invasion, and apoptosis. Our results showed that miR-150 expression in OS cells (MG63, Saos-2, SOSP-9607, and U2OS) was significantly lower compared to the osteoblast hFOB1.19 cell line (all p < 0.01). The expression level of miR-150 in MG63 cells that were transfected with exogenous miR-150 mimics was markedly upregulated, while the miR-150 expression level in the inhibitor group was significantly downregulated (both p < 0.01). Similar results were also found in SOSP-9607 cells. Importantly, exogenous miR-150 expression stimulated cell apoptosis and inhibited proliferation, invasion, and migration. A luciferase reporter assay displayed that miR-150 also regulated Sp1 expression by targeting its 3′-UTR, and qRT-PCR and Western blotting showed that elevated levels of miR-150 may reduce Sp1 protein expression. The mRNA and protein levels of Sp1 were upregulated after transfection with a Sp1-expression plasmid and partially reversed the inhibitory effects of miR-150 on cell proliferation, invasion, and metastasis in MG63 and SOSP-9607 cells, as well as promoted cell apoptosis. In conclusion, miR-150 inhibits cell proliferation, invasion, and metastasis and stimulates cell apoptosis by regulating the expression of Sp1. Therefore, miR-150 may be a potential clinical target for the treatment of OS patients.

PGNTs display distinct clinicopathologic and imaging characteristics and indicate a favorable prognosis. However, recurrences sometimes occur. Immunohistochemistry facilitates the appropriate diagnosis of these tumors. Complete resection of the tumor is important for a favorable outcome.