Potential predictive value of cofilin-1 for metastasis occurrence in a small cohort of Argentinian patients with mid-low Breslow thickness melanoma.

Nowadays, histopathological criteria for melanocytic lesions are the mainstay prognostic factors for melanoma. However, there are cases in which these parameters fall short to predict melanoma spread. We recently demonstrated a correlation of cofilin-1 levels, a key protein for tumor invasion, with different histopathological parameters associated with melanoma malignancy as well as a negative correlation with survival. In order to broaden our previous findings, we aim to estimate the probability of a melanoma to metastasize as a function of both a conventional histopathological parameter (Breslow thickness, BT) and cofilin-1's immunohistochemical expression levels, which we propose as a potential marker for metastasis. We used a Bayesian approach to analyze clinical and cofilin-1 datasets formerly obtained from a patients' small cohort diagnosed with malignant melanocytic lesions since 2000 until 2008; classified at different tumor stages with or without detected metastasis and with at least 5 years of clinical follow-up. Low BT values exhibited wide variance to predict metastasis occurrence, while the differential diagnostic value of cofilin-1 confirmed BT diagnosis or resulted more precise to predict outcome. Particularly, the probability of metastasis estimation improved when cofilin-1 was combined with BT for specific cases, where BT displayed large uncertainties. Our analysis and the cofilin-1 determination provided statistically significant prognostic value in mid-low BT melanomas, which could complement further evaluation criteria to assist diagnosis and treatment decision-making. Moreover, the combined use of cofilin-1 with BT, if validated in follow-up studies, would be feasible to help patients' selection for treatment and optimize health resources.

Cofilin-1 levels and intracellular localization are associated with melanoma prognosis in a cohort of patients.

Melanoma is an aggressive cancer with highly metastatic ability. We propose cofilin-1, a key protein in the regulation of actin dynamics and migration, as a prognostic marker. We determined cofilin-1 levels in a retrospective cohort of patients with melanomas and benign lesions of melanocytes (nevi) by immunohistochemistry. Higher cofilin-1 levels were found in malignant melanoma (MM) with Breslow Index (BI)>2 vs MM with BI<2, melanoma in situ (MIS) and nevi and also in MM with metastasis vs MM without detected metastasis. Kaplan-Meier survival curves were performed, clustering patients according to either the type of melanocytic lesions or cofilin-1 level. Survival curves demonstrated worse prognosis of patients with high vs low cofilin-1 levels. TCGA database analysis of melanoma also showed low survival in patients with upregulated cofilin-1 mRNA vs patients without alteration in CFL1 mRNA expression. As cofilin-1 has a dual function depending on its intracellular localization, we evaluated nuclear and cytoplasmic levels of cofilin-1 in melanoma and nevi samples by immunofluorescence. MM with high Breslow index and metastatic cells not only presented cytoplasmic cofilin-1, but also showed this protein at the nucleus. An increase in nuclear/cytoplasmic cofilin-1 mean fluorescence ratio was observed in MM with BI>2 vs MM with BI<2, MIS and nevi. In conclusion, an association of cofilin-1 levels with malignant features and an inverse correlation with survival were demonstrated. Moreover, this study suggests that not only the higher levels of cofilin-1, but also its nuclear localization can be proposed as marker of worse outcome of patients with melanoma.

Inhibition of brain ST8SiaIII sialyltransferase leads to impairment of procedural memory in mice.

Several glycoproteins in mammalian brains contain α2,8-linked disialic acid residues. We previously showed a constant expression of disialic acid (DiSia) in the hippocampus, olfactory bulb and cortex, and a gradual decrease of expression in the cerebellum from neonatal to senile mice. Previous publications indicate that neurite extension of neuroblastoma-derived Neuro2A cells is inhibited in the presence of DiSia antibody. Based on this, we treated Neuro2A cell cultures with RNA interference for ST8SiaIII mRNA, the enzyme responsible for DiSia formation. We observed that neurite extension was inhibited by this treatment. Taking this evidence into consideration and the relationship of the cerebellum with learning and memory, we studied the role of DiSia expression in a learning task. Through delivery of pST8SiaIII into the brains of C57BL/6 neonatal mice, we inhibited the expression of ST8SiaIII. ST8SiaIII mRNA and protein expressions were analyzed by real-time PCR and western blot, respectively. In this work, we showed that pST8SiaIII-treated mice presented a significantly reduced level of ST8SiaIII mRNA in the cerebellum (p<0.01) in comparison to control mice at 8 days after treatment. It is also noted that these levels returned to baseline values in the adulthood. Then, we evaluated behavioural performance in the T-Maze, a learning task that estimates procedural memory. At all ages, pST8SiaIII-treated mice showed a lower performance in the test session, being most evident at older ages (p<0.001). Taken all together, we conclude that gene expression of ST8SiaIII is necessary for some cognitive tasks at early postnatal ages, since reduced levels impaired procedural memory in adult mice.

Differential expression of disialic acids in the cerebellum of senile mice.

It is known that disialic acids (diSia) are present in the mammalian brain. However, the precise anatomical distribution and the chronology of its expression along life are not well studied yet. It is accepted that the transfer of diSia in the brain is mediated mainly by the enzyme ST8Sia III (α2,8-sialyltransferase III). We studied the expression of diSia glycoepitopes and of the ST8Sia III gene in different structures of the mouse brain at different postnatal stages by immunohistochemistry and real-time polymerase chain reaction, respectively. C57BL/6 mice of different stages were used. Samples of hippocampus, olfactory bulb, cortex and cerebellum were processed for studies of molecular biology and immunohistochemistry. Histological analysis revealed an important decrease in diSia labeling in the senile cerebellum compared with other structures and stages (P â‰ª 0.001). In concordance with these results, a significant decrease in ST8Sia III gene expression was found in the cerebellum of senile animals (P < 0.001). These results suggest that diSia are constantly expressed but with differential expression in various areas of the mouse central nervous system. On the other hand, the concordance in the decreased expression of ST8Sia III and the diSia epitope in the cerebellum of senile animals suggest a role of diSia in this structure or, inversely, an influence of aging on the expression of diSia in the cerebellum. Further research in that direction could elucidate the roles of diSia in brain function in health and disease.