Combined Targeting of Pathogenetic Mechanisms in Pancreatic Neuroendocrine Tumors Elicits Synergistic Antitumor Effects

Buparlisib; Combination therapy; Primary human tumoroidsBuparlisib; Terapia de combinación; Tumoroides humanos primariosBuparlisib; Teràpia combinada; Tumoroides humans primarisPancreatic neuroendocrine neoplasms (PanNENs) are the second most common malignancy of the pancreas. Surgery remains the only curative treatment for localized disease. For patients with inoperable advanced or metastatic disease, few targeted therapies are available, but their efficacy is unpredictable and variable. Exploiting prior knowledge on pathogenetic processes involved in PanNEN tumorigenesis, we tested buparlisib (PI3K inhibitor) and ribociclib (CDK4/6 inhibitor), as single agents or in combination, in different preclinical models. First, we used cell lines representative of well-differentiated (INS-1E, NT-3) and poorly differentiated (BON-1) PanNENs. The combination of buparlisib with ribociclib reduced the proliferation of 2D and 3D spheroid cultures more potently than the individual drugs. Buparlisib, but not ribociclib, induced apoptosis. The anti-proliferative activity of the drugs correlated with downstream target inhibition at mRNA and protein levels. We then tested the drugs on primary islet microtissues from a genetic PanNET animal model (Men1-defective mice) and from wild-type mice: the drug combination was effective against the former without altering islet cell physiology. Finally, we treated PanNET patient-derived islet-like 3D tumoroids: the combination of buparlisib with ribociclib was effective in three out of four samples. Combined targeting of PI3K and CDK4/6 is a promising strategy for PanNENs spanning various molecular and histo-pathological features.This work was supported by the German Research Foundation (Deutsche Forschungsgemeinschaft-DFG) within the CRC/Transregio 205/2, project number 314061271-TRR 205 (to NSP); and by the Deutsche Krebshilfe (# 70113629 to NSP). Ilaria Marinoni was supported by Wilhelm Sander Stiftung (# 2017.073.2). Aurel Perren was supported by the Swiss Cancer Research Foundation (KFS-4227-08-2017)

Combined Targeting of Pathogenetic Mechanisms in Pancreatic Neuroendocrine Tumors Elicits Synergistic Antitumor Effects.

Pancreatic neuroendocrine neoplasms (PanNENs) are the second most common malignancy of the pancreas. Surgery remains the only curative treatment for localized disease. For patients with inoperable advanced or metastatic disease, few targeted therapies are available, but their efficacy is unpredictable and variable. Exploiting prior knowledge on pathogenetic processes involved in PanNEN tumorigenesis, we tested buparlisib (PI3K inhibitor) and ribociclib (CDK4/6 inhibitor), as single agents or in combination, in different preclinical models. First, we used cell lines representative of well-differentiated (INS-1E, NT-3) and poorly differentiated (BON-1) PanNENs. The combination of buparlisib with ribociclib reduced the proliferation of 2D and 3D spheroid cultures more potently than the individual drugs. Buparlisib, but not ribociclib, induced apoptosis. The anti-proliferative activity of the drugs correlated with downstream target inhibition at mRNA and protein levels. We then tested the drugs on primary islet microtissues from a genetic PanNET animal model (Men1-defective mice) and from wild-type mice: the drug combination was effective against the former without altering islet cell physiology. Finally, we treated PanNET patient-derived islet-like 3D tumoroids: the combination of buparlisib with ribociclib was effective in three out of four samples. Combined targeting of PI3K and CDK4/6 is a promising strategy for PanNENs spanning various molecular and histo-pathological features

Combined Targeting of Pathogenetic Mechanisms in Pancreatic Neuroendocrine Tumors Elicits Synergistic Antitumor Effects

Pancreatic neuroendocrine neoplasms (PanNENs) are the second most common malignancy of the pancreas. Surgery remains the only curative treatment for localized disease. For patients with inoperable advanced or metastatic disease, few targeted therapies are available, but their efficacy is unpredictable and variable. Exploiting prior knowledge on pathogenetic processes involved in PanNEN tumorigenesis, we tested buparlisib (PI3K inhibitor) and ribociclib (CDK4/6 inhibitor), as single agents or in combination, in different preclinical models. First, we used cell lines representative of well-differentiated (INS-1E, NT-3) and poorly differentiated (BON-1) PanNENs. The combination of buparlisib with ribociclib reduced the proliferation of 2D and 3D spheroid cultures more potently than the individual drugs. Buparlisib, but not ribociclib, induced apoptosis. The anti-proliferative activity of the drugs correlated with downstream target inhibition at mRNA and protein levels. We then tested the drugs on primary islet microtissues from a genetic PanNET animal model (Men1-defective mice) and from wild-type mice: the drug combination was effective against the former without altering islet cell physiology. Finally, we treated PanNET patient-derived islet-like 3D tumoroids: the combination of buparlisib with ribociclib was effective in three out of four samples. Combined targeting of PI3K and CDK4/6 is a promising strategy for PanNENs spanning various molecular and histo-pathological features

Functional characterization of Tribbles pseudokinases in gastric cancer

Introduction: Gastric cancer (GC) is the fifth most common cancer and the fourth leading cause of cancer-related deaths worldwide. It is often diagnosed at advanced stages and is mostly resistant to conventional chemotherapy. To help GC management, there is a need to develop new biomarkers: they are needed to improve diagnosis, as well as novel therapeutic targets that may lead to the development of effective therapies. TRIB2 belongs to the Tribbles family of serine/threonine pseudokinases, scaffold proteins involved in several cellular processes. In cancer, TRIB2 can act either as an oncogene or a tumor suppressor gene, depending on the cellular context. TRIB2 also promotes drug resistance in different cancer types. Since this protein has never been investigated in GC, our study aimed at addressing the significance of TRIB2 in this tumor. Material & Methods: We performed data mining of The Cancer Genome Atlas (TCGA) Stomach Adenocarcinoma (STAD) dataset and of the Broad Institute Cancer Cell Line Encyclopedia (CCLE) GC dataset. Based on in silico results, we then investigated the impact of lentiviral-mediated TRIB2 overexpression (OE) in four GC cell lines (MKN45, KATO-III, MKN74 and NCI-N87) with chromosomal instability phenotype (CIN). The impact of TRIB2 OE was evaluated by different functional assays, including cell proliferation, motility, colony formation and cell cycle analysis. Moreover, we investigated the mitogen-activated protein kinase (MAPK) downstream pathway and the possible involvement of TRIB2 in drug response, following cell treatments with two agents commonly used in GC chemotherapy (5-fluorouracil and doxorubicin). Results: Data mining of the TCGA STAD dataset and of the CCLE dataset revealed a limited number of genetic and genomic alterations and a wide range of mRNA expression levels of TRIBs in GC tissues, and in GC cell lines, respectively. The analysis of TRIBs expression of STAD cases sorted by molecular phenotypes showed that a lower TRIB2 mRNA expression was statistically significantly associated with tumors characterized by chromosomal instability (CIN) compared to tumors characterized by microsatellite instability (MSI). In addition, T4 stage in CIN tumors was statistically significantly associated with low TRIB2 expression. In vitro, TRIB2 OE was able to reduce proliferation and colony formation ability in MKN45 and NCI-N87 cells. Furthermore, TRIB2 OE induced cell cycle arrest in G2/M phase in MKN45 cells and reduced migration ability in NCI-N87 compared to the control cells. On the other side, TRIB2 OE did not affect the MAPK pathway and no differences were detected between TRIB2-overexpressing cells and control cells treated both with 5-fluorouracil and doxorubicin

Tribbles Genes in Gastric Cancer: A Tumor-Suppressive Role for TRIB2

: Tribbles pseudokinases (TRIB1-3) are important signaling modulators involved in several cancers. However, their function in gastric cancer (GC) remains undefined. GC is still a deadly disease since the lack of sensitive and specific biomarkers for early diagnosis and therapy response prediction negatively affects patients' outcome. The identification of novel molecular players may lead to more effective diagnostic and therapeutic avenues. Therefore, we investigated the role of TRIB genes in gastric tumorigenesis. Data mining of the TCGA dataset revealed that chromosomal instability (CIN) tumors have lower TRIB2 and higher TRIB3 expression versus microsatellite instability (MSI)-high tumors, while TRIB1 levels are similar in both tumor types. Moreover, in CIN tumors, low TRIB2 expression is significantly associated with aggressive stage IV disease. As no studies on TRIB2 in GC are available, we focused on this gene for further in vitro analyses. We checked the effect of TRIB2 overexpression (OE) on MKN45 and NCI-N87 CIN GC cell lines. In MKN45 cells, TRIB2 OE reduced proliferation and colony formation ability and induced G2/M arrest, while it decreased the proliferation and cell motility of NCI-N87 cells. These effects were not mediated by the MAPK pathway. Our results suggest a tumor-suppressive function of TRIB2 in GC with a CIN phenotype