Current trends in ATRA delivery for cancer therapy

All-Trans Retinoic Acid (ATRA) is the most active metabolite of vitamin A. It is critically involved in the regulation of multiple processes, such as cell differentiation and apoptosis, by activating specific genomic pathways or by influencing key signaling proteins. Furthermore, mounting evidence highlights the anti-tumor activity of this compound. Notably, oral administration of ATRA is the first choice treatment in Acute Promyelocytic Leukemia (APL) in adults and NeuroBlastoma (NB) in children. Regrettably, the promising results obtained for these diseases have not been translated yet into the clinics for solid tumors. This is mainly due to ATRA-resistance developed by cancer cells and to ineffective delivery and targeting. This up-to-date review deals with recent studies on different ATRA-loaded Drug Delivery Systems (DDSs) development and application on several tumor models. Moreover, patents, pre-clinical, and clinical studies are also reviewed. To sum up, the main aim of this in-depth review is to provide a detailed overview of the several attempts which have been made in the recent years to ameliorate ATRA delivery and targeting in cancer

Loss of ATP2C1 function promotes trafficking and degradation of NOTCH1: Implications for Hailey-Hailey disease

Hailey-Hailey disease (HHD) is a rare autosomal dominantly inherited disorder caused by mutations in the ATP2C1 gene that encodes an adenosine triphosphate (ATP)-powered calcium channel pump. HHD is characterized by impaired epidermal cell-to-cell adhesion and defective keratinocyte growth/differentiation. The mechanism by which mutant ATP2C1 causes HHD is unknown and current treatments for affected individuals do not address the underlying defects and are ineffective. Notch signalling is a direct determinant of keratinocyte growth and differentiation. We found that loss of ATP2C1 leads to impaired Notch1 signalling, thus deregulation of the Notch signalling response is therefore likely to contribute to HHD manifestation. NOTCH1 is a transmembrane receptor and upon ligand binding, the intracellular domain (NICD) translocates to the nucleus activating its target genes. In the context of HHD, we found that loss of ATP2C1 function promotes upregulation of the active NOTCH1 protein (NICD-Val1744). Here, deeply exploring this aspect, we observed that NOTCH1 activation is not associated with the transcriptional enhancement of its targets. Moreover, in agreement with these results, we found a cytoplasmic localization of NICD-Val1744. We have also observed that ATP2C1-loss is associated with the degradation of NICD-Val1744 through the lysosomal/proteasome pathway. These results show that ATP2C1-loss could promote a mechanism by which NOTCH1 is endocytosed and degraded by the cell membrane. The deregulation of this phenomenon, finely regulated in physiological conditions, could in HHD lead to the deregulation of NOTCH1 with alteration of skin homeostasis and disease manifestation

po 393 notch3 and cxcr4 cross signalling sustains acute t cell leukaemia progression

Introduction Acute T-cell lymphoblastic leukaemia (T-ALL) is a childhood cancer, characterised by infiltration of immature T-cells in bone marrow. Notch hyperactivation is a major driver of T-ALL development where CXCL12/CXCR4 axis plays an important role in T-ALL maintenance. In thymus the lympho-stromal communication drives progressive maturation of T-cells. Notch receptors regulate T-cell fate choices, dominating early steps of thymocyte maturation. In T-cell differentiation, Notch3, in association with pre-TCR and chemochine receptor CXCR4, govern the transition from double negative (DN) to double positive (DP) thymocytes. Previously, our laboratory demonstrated the lymphomagenic potential of Notch3 by creating a transgenic mouse model (N3-ICtg), characterised by the constitutive activation of the intracellular domain (IC) of Notch3 receptor (N3-IC) in immature thymocytes. In order to investigate the oncogenic cross-talk between Notch3 and CXCR4 in T-ALL progression, we analysed DP T-cells in different lymphoid compartments of N3-ICtg mice. Material and methods Freshly isolated cells from thymus, blood and bone marrow of N3-ICtg and WT mice were analysed by flow cytometry in order to verify the presence of DP T-cells and their cell-surface expression of CXCR4 and Notch3 receptors. Experiments in TALL1, a human T-ALL leukemic CD3 + /CD4 + /CD8 + cell line characterised by the activation of Notch3 and high expression of CXCR4, were also performed. TALL1 cells were treated with γ-secretase inhibitor (GSI) or their gene expression of Notch3 was silenced and then analysed by flow cytometry, RT-PCR and western blot. Statistical interpretation of the results was performed. Results and discussions DP-gated thymocytes obtained by N3-ICtg mice have shown a high co-expression of Notch3 and CXCR4 and a high migratory ability induced by SDF-1. An anomalous percentage representation of these DP T-cells at different ages in circulating blood, spleen and bone morrow may suggest an interaction between CXCR4 and Notch3 in T-ALL cell propagation. Experiments in human TALL1 cell line with Notch3 targeted inhibition suggest a modulated expression of CXCR4 through a β-arrestin1-mediated mechanism. CXCR4-antagonists treatment will further elucidate the molecular crosstalk between the two receptors. Conclusion Notch3 abnormal pathway, through boosting the expression of CXCR4 on cell-surface, may play a role in DP T-cells egress from thymus, and define a possible mechanism of 'pre-leukemic-cells' dissemination

Current views on the role of Notch signaling and the pathogenesis of human leukemia

The Notch signaling pathway is highly conserved from Drosophila to humans and plays an important role in the regulation of cellular proliferation, differentiation and apoptosis

Notch signaling in female cancers. A multifaceted node to overcome drug resistance

Drug resistance is one of the main challenges in cancer therapy, including in the treatment of female-specific malignancies, which account for more than 60% of cancer cases among women. Therefore, elucidating the underlying molecular mechanisms is an urgent need in gynecological cancers to foster novel therapeutic approaches. Notably, Notch signaling, including either receptors or ligands, has emerged as a promising candidate given its multifaceted role in almost all of the hallmarks of cancer. Concerning the connection between Notch pathway and drug resistance in the afore-mentioned tumor contexts, several studies focused on the Notch-dependent regulation of the cancer stem cell (CSC) subpopulation or the induction of the epithelial-to-mesenchymal transition (EMT), both features implicated in either intrinsic or acquired resistance. Indeed, the present review provides an up-to-date overview of the published results on Notch signaling and EMT- or CSC-driven drug resistance. Moreover, other drug resistance-related mechanisms are examined such as the involvement of the Notch pathway in drug efflux and tumor microenvironment. Collectively, there is a long way to go before every facet will be fully understood; nevertheless, some small pieces are falling neatly into place. Overall, the main aim of this review is to provide strong evidence in support of Notch signaling inhibition as an effective strategy to evade or reverse resistance in female-specific cancers

Notch signaling activation as a hallmark for triple-negative breast cancer subtype

Triple-negative breast cancer (TNBC) is a subgroup of 15%-20% of diagnosed breast cancer patients. It is generally considered to be the most difficult breast cancer subtype to deal with, due to the lack of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), which usually direct targeted therapies. In this scenario, the current treatments of TNBC-affected patients rely on tumor excision and conventional chemotherapy. As a result, the prognosis is overall poor. Thus, the identification and characterization of targets for novel therapies are urgently required. The Notch signaling pathway has emerged to act in the pathogenesis and tumor progression of TNBCs. Firstly, Notch receptors are associated with the regulation of tumor-initiating cells (TICs) behavior, as well as with the aetiology of TNBCs. Secondly, there is a strong evidence that Notch pathway is a relevant player in mammary cancer stem cells maintenance and expansion. Finally, Notch receptors expression and activation strongly correlate with the aggressive clinicopathological and biological phenotypes of breast cancer (e.g., invasiveness and chemoresistance), which are relevant characteristics of TNBC subtype. The purpose of this up-to-date review is to provide a detailed overview of the specific role of all four Notch receptors (Notch1, Notch2, Notch3, and Notch4) in TNBCs, thus identifying the Notch signaling pathway deregulation/activation as a pathognomonic feature of this breast cancer subtype. Furthermore, this review will also discuss recent information associated with different therapeutic options related to the four Notch receptors, which may be useful to evaluate prognostic or predictive indicators as well as to develop new therapies aimed at improving the clinical outcome of TNBC patients

Role of Notch3 in sustaining UPR signaling in Notch3-overexpressing T-cell acute lymphoblastic leukemia.

Introduction. Aberrant Notch signaling has been implicated in the development of several diseases, including T-cell acute lymphoblastic leukemia (T-ALL), a malignant disorder that originates from hematopoietic precursors committed to T-cell lineage. Survival rates in T-ALL patients have greatly improved in the last decades but still a substantial number of patients will relapse and die. An increased understanding of T-ALL biology has opened opportunities for the development of targeted therapies for the treatment of this disease. Recently, several studies suggest the role of the unfolded protein response (UPR) in acute leukemias. UPR is a conserved adaptive signaling pathway which tries to restore protein homeostasis mainly after Endoplasmatic Reticulum (ER) stress. Since it has been demonstrated that cancer cells are able to maintain malignancy by acquiring therapy resistance through its UPR signaling, the disruption of UPR could be considered a selective anti-leukemia therapy. Our main aim is to demonstrate that Juglone, a naturally-occurring naphtoquinone, is able to induce ER stress/UPR perturbation, thus having therapeutic effects on T-ALL cells. Methods. Notch3-positive and Notch3-negative human TALL leukemia cells; pharmacological treatments; PI/Annexin staining and cytofluorimetric analysis; RNA interference; RT-qPCR; Western blot. Results. Here we show the mechanism whereby Juglone induced apoptosis in T-cell acute lymphoblastic leukemia (T-ALL) cells. Time course studies indicate that initial apoptotic events are inhibition of proteasome activity, concomitant with an increased endoplasmic reticulum (ER) stress signaling. Moreover, Juglone induced Notch downregulation in leukemic cells: however, while Notch3 inhibition contributed to amplify Juglone-induced T-ALL cell apoptosis, Notch1 did not. We futher demostrate that Notch3 downregulation during Juglone treatment prevents leukemia cells from engaging a functional UPR in order to buffer the Juglone-mediated proteotoxic stress in the ER, thus finally inducing T-ALL apoptosis. Conclusions. Our findings provide a rationale to target the ER stress/UPR signaling through Notch3 inhibition, Juglone-dependent, in a T-ALLs subset displaying upregulation of Notch3