Publications

Novel N-cadherin expression has been linked to the invasive phenotype in bladder tumors yet a primary role for N-cadherin in invasion has not been defined in this model. To address this, N-cadherin was stably transfected into E-cadherin expressing bladder carcinoma cells. This resulted in an enhanced invasive capacity in in vitro assays that was blocked by incubation with an N-cadherin function-blocking antibody in a dose-dependent manner. Analysis of the signaling pathway(s) implicated in N-cadherin-mediated invasion in bladder carcinoma cell lines revealed no correlation between MAPK signaling and invasion, in the presence or absence of fibroblast growth factor 2. Also, while MAPK and p38 kinase inhibitors did not alter the invasive behavior of these cells, an increase in the phosphorylation of Akt at serine-473 was detected in N-cadherin transfectants, suggestive of N-cadherin-mediated Akt activation in bladder cell invasion. Incubation of N-cadherin transfectants with either PI3 kinase or Akt inhibitors resulted in a significant decrease in the invasive capacity of these cells. Exposure of cells to PP2, a src family kinase inhibitor, also decreased the invasive potential of N-cadherin transfectants and resulted in reduced phosphorylation of Akt. The involvement of Akt signaling in bladder cell invasion was also supported by the inhibition of bladder cell invasion by cells constitutively expressing an activated Akt kinase, using the PI3 kinase and Akt inhibitors and PP2. These results suggest that activation of PI3/AKT kinase following N-cadherin expression contributes to the increased invasive potential of bladder carcinoma cells.

Tissue engineering is an application for gene therapy that is in its infancy. We show that simple liposomal-mediated gene transfer could result in a potentially useful biological effect in the field of wound healing. cDNA encoding the 165 amino acid form of vascular endothelial growth factor complexed to commercially available liposomes was injected into rat skin 1 week before raising a random pattern 3 x 10 cm flap. The flap survival was enhanced by 14 percent, and was accomplished without accessing the arterial inflow of the territory. These results were statistically significant (p<0.002) and reproducible. No adverse effects were seen. Histological analysis of the angiogenesis localized much of the new vessel formation to the area around the hair follicles. Polymerase chain reaction amplification of extracted flap tissue confirmed the presence of the transgene.

BACKGROUND: Mutations in fibroblast growth factor 3 receptor (FGFR3) are frequent events in low-grade bladder tumors. To assess the potential utility of the detection of FGFR3 mutations in a screening modality, the authors analyzed urine sediment DNA samples from 192 patients in a retrospective study.

METHODS: Urine sediment DNA samples from 192 patients were prepared. Seventy-two patients had undergone transurethral resection (TURBT group) of mainly Ta lesions and 120 patients had undergone cystectomy (cystectomy group). The majority of patients in the cystectomy group had more advanced tumors compared with patients in the TURBT group. DNA preparations were screened for FGFR3 mutations in exons 7, 10, and 15 using single-strand conformation polymorphism (SSCP) and DNA sequencing.

RESULTS: Using SSCP, 67% of patients in the TURBT group and 28% in the cystectomy group displayed FGFR3 mutations. Comparative analysis of cytology results and FGFR3 mutational analysis were performed in 122 cases. Within the TURBT group, FGFR3 mutation analysis outperformed cytology. FGFR3 mutation analysis identified change in 68% of urine sediment DNA samples whereas cytology recorded the presence of tumor cells in 32% of the DNA samples. In the cystectomy group, cytology outperformed FGFR3 mutation analysis. Cytology recorded tumor detection in 90% of patients, while SSCP identified mutational change in 24%.

CONCLUSIONS: Combining FGFR3 mutation results with cytology in both groups correctly identified tumor presence in 105 of 122 (86%) of patients. The greater sensitivity of FGFR3 mutation detection over cytology in identifying the presence of low-grade, superficial bladder tumors represents a potential new tool to complement standard cytology in screening patients for bladder tumors and recurrent disease.

Using an established rat peripheral-nerve regeneration model, the authors have demonstrated enhancement of regeneration following subcutaneous priming of bioresorbable poly(lactic-co-glycolic)acid (PLGA) guides in vivo. Four weeks after nerve reconstruction, regeneration of the peripheral nerve through the cell-infiltrated guides displayed a significant increase in the total axon number and myelination status recorded in primed over unprimed guides, demonstrating the importance of cell-mediated events in the regeneration process. To define the different components enhancing nerve regeneration in this model, they have focused on identifying factors capable of eliciting Schwann-cell migration, since this has been identified as an early and necessary event in nerve regeneration. Using an in vitro migration assay, screening of a limited number of cellular and extracellular factors has demonstrated differential promotion of Schwann-cell migration. Of interest, combining fibronectin and bFGF resulted in a two-fold enhancement in Schwann-cell migration over that recorded with either alone. These results describe a rapid screening process for identifying various molecules and combinations thereof, with potential involvement in Schwann-cell migration. Coupling these findings to the use of the PLGA guide as an in vivo delivery system provides a rationale for the selection of exogenous factors to test for the enhancement of peripheral-nerve regeneration.