Differential Competitive Growth of Transgenic Subclones of Neuroblastoma Cells Expressing Different Levels of Cathepsin D Co-Cultured in 2D and 3D in Response to EGF: Implications in Tumor Heterogeneity and Metastasis

Neuroblastoma (NB) is an embryonal tumor arising from the sympathetic central nervous system. The epidermal growth factor (EGF) plays a role in NB growth and metastatic behavior. Recently, we have demonstrated that cathepsin D (CD) contrasts EGF-induced NB cell growth in 2D by downregulating EGFR/MAPK signaling. Aggressive NB is highly metastatic to the bone and the brain. In the metastatic process, adherent cells detach to form clusters of suspended cells that adhere once they reach the metastatic site and form secondary colonies. Whether CD is involved in the survival of metastatic NB clones is not known. Therefore, in this study, we addressed how CD differentially affects cell growth in suspension versus the adherent condition. To mimic tumor heterogeneity, we co-cultured transgenic clones silenced for or overexpressing CD. We compared the growth kinetics of such mixed clones in 2D and 3D models in response to EGF, and we found that the Over CD clone had an advantage for growth in suspension, while the CD knocked-down clone was favored for the adherent growth in 2D. Interestingly, on switching from 3D to 2D culture conditions, the expression of E-cadherin and of N-cadherin increased in the KD-CD and Over CD clones, respectively. The fact that CD plays a dual role in cancer cell growth in 2D and 3D conditions indicates that during clonal evolution, subclones expressing different level of CD may arise, which confers survival and growth advantages depending on the metastatic step. By searching the TCGA database, we found up to 38 miRNAs capable of downregulating CD. Interestingly, these miRNAs are associated with biological processes controlling cell adhesion and cell migration. The present findings support the view that during NB growth on a substrate or when spreading as floating neurospheres, CD expression is epigenetically modulated to confer survival advantage. Thus, epigenetic targeting of CD could represent an additional strategy to prevent NB metastases.

Adjustment of insulin doses when switching from glargine 100 U/ml or detemir to degludec: an observational study

BACKGROUND

Degludec is a long-acting insulin with a longer duration of action and a greater day-to-day reproducibility of absorption in comparison with previous long-acting insulin formulations. The aim is the definition of the change in insulin needs in patients switching from detemir/glargine to degludec in real-life conditions.

METHODS

In this retrospective cohort observational study, all outpatients with either type 1 or type 2 diabetes, starting therapy with degludec insulin-after a prior treatment with either detemir or glargine insulin for at least 6 months-were included.

RESULTS

The analysis was performed on 266 patients, 172 and 96 with type 1 and type 2 diabetes, respectively. The equations describing the relationship between baseline and follow-up doses of basal insulin (6 months) were Y = 3.39 + 0.78X and Y = 0.44 + 0.69X, in patients receiving detemir/glargine either once or twice daily, respectively (Y = degludec dose at 6 months and X = basal insulin dose at switch). The corresponding equations for prandial insulin doses were y = 1.83 + 0.83*x and y = 2.85 + 0.80*x for those on pre-switch once or twice-daily basal insulin, respectively. In type 2 diabetes, the switch was associated with a reduction of basal insulin doses only in those with a prior twice-daily treatment with basal insulin. The reduction of prandial insulin reached statistical significance only in patients previously treated with basal insulin once daily.

CONCLUSIONS

The present results provide a suggestion for a simple method for the adjustment of basal and prandial insulin doses in type 1 diabetic patients, switching from glargine or detemir to degludec.