In Vitro Evaluation of Notch Inhibition to Enhance Efficacy of Radiation Therapy in Melanoma

Interplay of Developmental Hippo-Notch Signaling Pathways with the DNA Damage Response in Prostate Cancer

Prostate cancer belongs in the class of hormone-dependent cancers, representing a major cause of cancer incidence in men worldwide. Since upon disease onset almost all prostate cancers are androgen-dependent and require active androgen receptor (AR) signaling for their survival, the primary treatment approach has for decades relied on inhibition of the AR pathway via androgen deprivation therapy (ADT). However, following this line of treatment, cancer cell pools often become resistant to therapy, contributing to disease progression towards the significantly more aggressive castration-resistant prostate cancer (CRPC) form, characterized by poor prognosis. It is, therefore, of critical importance to elucidate the molecular mechanisms and signaling pathways underlying the progression of early-stage prostate cancer towards CRPC. In this review, we aim to shed light on the role of major signaling pathways including the DNA damage response (DDR) and the developmental Hippo and Notch pathways in prostate tumorigenesis. We recapitulate key evidence demonstrating the crosstalk of those pathways as well as with pivotal prostate cancer-related 'hubs' such as AR signaling, and evaluate the clinical impact of those interactions. Moreover, we attempt to identify molecules of the complex DDR-Hippo-Notch interplay comprising potentially novel therapeutic targets in the battle against prostate tumorigenesis.

Dual Knockdown of Musashi RNA-Binding Proteins MSI-1 and MSI-2 Attenuates Putative Cancer Stem Cell Characteristics and Therapy Resistance in Ovarian Cancer Cells

In ovarian cancer, therapy resistance mechanisms complicate cancer cell eradication. Targeting Musashi RNA-binding proteins (MSI) may increase therapeutic efficacy. Database analyses were performed to identify gene expression associations between MSI proteins and key therapy resistance and cancer stem cell (CSC) genes. Then, ovarian cancer cells were subjected to siRNA-based dual knockdown of MSI-1 and MSI-2. CSC and cell cycle gene expression was investigated using quantitative polymerase chain reaction (qPCR), western blots, and flow cytometry. Metabolic activity and chemoresistance were assessed by MTT assay. Clonogenic assays were used to quantify cell survival post-irradiation. Database analyses demonstrated positive associations between MSI proteins and putative CSC markers NOTCH, MYC, and ALDH4A1 and negative associations with NOTCH inhibitor NUMB. MSI-2 expression was negatively associated with the apoptosis regulator p21. MSI-1 and MSI-2 were positively correlated, informing subsequent dual knockdown experiments. After MSI silencing, CSC genes were downregulated, while cell cycle progression was reduced. Metabolic activity was decreased in some cancer cells. Both chemo- and radioresistance were reduced after dual knockdown, suggesting therapeutic potential. Dual knockdown of MSI proteins is a promising venue to impede tumor growth and sensitize ovarian cancer cells to irradiation and chemotherapy.