Glial cell line-derived neurotrophic factor added to a sciatic nerve fragment grafted in a spinal cord gap ameliorates motor impairments in rats and increases local axonal growth

Purpose: The aversive nature of regenerative milieu is the main problem related to the failure of neuronal restoration in the injured spinal cord which however might be addressed with an adequate repair intervention. We evaluated whether glial cell line-derived neurotrophic factor (GDNF) may increase the ability of sciatic nerve graft, placed in a gap promoted by complete transections of the spinal cord, to enhance motor recovery and local fiber growth. Methods: Rats received a 4 mm-long gap at low thoracic level and were repaired with a fragment of the sciatic nerve. GDNF was added (NERVE+GDNF) or not to the grafts (NERVE-GDNF). Motor behavior score (BBB) and sensorimotor tests-linked to the combined behavior score (CBS), which indicate the degree of the motor improvement and the percentage of functional deficit, respectively, and also the spontaneous motor behavior in an open field by means of an infrared motion sensor activity monitor were analyzed. At the end of the third month post surgery, the tissue composed by the graft and the adjacent regions of the spinal cord was removed and submitted to the immunohistochemistry of the neurofilament-200 (NF-200), growth associated protein-43 (GAP-43), microtubule associated protein-2 (MAP-2), 5-hidroxytryptamine (serotonin, 5-HT) and calcitonin gene related peptide (CGRP). The immunoreactive fibers were quantified at the epicenter of the graft by means of stereological procedures. Results: Higher BBB and lower CBS levels (p < 0.001) were found in NERVE+GDNF rats. GDNF added to the graft increased the levels of individual sensorimotor tests mainly at the third month. Analysis of the spontaneous motor behavior showed decreases in the time and number of small movement events by the third month without changes in time and number of large movement events in the NERVE+GDNF rats. Immunoreactive fibers were encountered inside the grafts and higher amounts of NF-200, GAP-43 and MAP-2 fibers were found in the epicenter of the graft when GDNF was added. A small amount of descending 5-HT fibers was seen reentering in the adjacent caudal levels of the spinal cords which were grafted in the presence of GDNF, event that has not occurred without the neurotrophic factor. GDNF in the graft also led to a large amount of MAP-2 perikarya and fibers in the caudal levels of the cord gray matter, as determined by the microdensitometric image analysis. Conclusions: GDNF added to the nerve graft favored the motor recovery, local neuronal fiber growth and neuroplasticity in the adjacent spinal cord.

Prognostic value of NDRG1 and SPARC protein expression in breast cancer patients

An increasing number of studies have shown altered expression of secreted protein acidic and rich in cysteine (SPARC) and N-myc down-regulated gene (NDRG1) in several malignancies, including breast carcinoma; however, the role of these potential biomarkers in tumor development and progression is controversial. In this study, NDRG1 and SPARC protein expression was evaluated by immunohistochemistry on tissue microarrays containing breast tumor specimens from patients with 10 years of follow-up. NDRG1 and SPARC protein expression was determined in 596 patients along with other prognostic markers, such as ER, PR, and HER2. The status of NDRG1 and SPARC protein expression was correlated with prognostic variables and patient clinical outcome. Immunostaining revealed that 272 of the 596 cases (45.6%) were positive for NDRG1 and 431 (72.3%) were positive for SPARC. Statistically significant differences were found between the presence of SPARC and NDRG1 protein expression and standard clinicopathological variables. Kaplan-Meier analysis showed that NDRG1 positivity was directly associated with shorter disease-free survival (DFS, P < 0.001) and overall survival (OS, P < 0.001). In contrast, patients expressing low levels of SPARC protein had worse DFS (P = 0.001) and OS (P = 0.001) compared to those expressing high levels. Combined analysis of the two markers indicated that DFS (P < 0.001) and OS rates (P < 0.001) were lowest for patients with NDRG1-positive and SPARC-negative tumors. Furthermore, NDRG1 over-expression and SPARC down-regulation correlated with poor prognosis in patients with luminal A or triple-negative subtype breast cancer. On multivariate analysis using a Cox proportional hazards model, NDRG1 and SPARC protein expression were independent prognostic factors for both DFS and OS of breast cancer patients. These data indicate that NDRG1 over-expression and SPARC down-regulation could play important roles in breast cancer progression and serve as useful biomarkers to better define breast cancer prognosis.