Novel Mouse Model for Analysis of Macrophage Function in Neuroblastoma

Background: Neuroblastoma is the third most common childhood cancer and accounts for 12% of cancer-associated deaths in children under the age of 15. Patients with high risk neuroblastoma have a poor 5-year survival rate of less than 50%. Neuroblastoma tumors treated with the histone deacetylase inhibitor (HDACi) vorinostat have increased infiltration of macrophages with upregulated immune cell-surface receptors. Neuroblastoma cells release VEGF and M-CSF, which may alter intratumoral macrophage populations. VEGF has also been implicated in alteration of amyloid precursor protein family processing. Our lab demonstrated that amyloid precursor protein 2 (APLP2), a member of the amyloid precursor protein family, plays an important role in the migration of tumor cells. APLP2 is known to be expressed by macrophages, but no studies have previously examined macrophage functions that are impacted by APLP2 in the context of neuroblastoma disease and its treatment by HDACi drugs. Significance of Problem: Because of the high morbidity and mortality associated with neuroblastoma, studies such as this one that are designed to comprehend the interaction of immunity and treatment in neuroblastoma are clinically significant. The results from this study are also expected to expand our comprehension of macrophage function and regulation, and thus will be of broad value in the immunology and oncology fields. Experimental Design and Results: We have treated neuroblastoma tumor cells in vitro with M344, an HDACi with structural similarity to vorinostat, and showed that M344 decreases neuroblastoma cell growth. In addition, we have generated mice that lack APLP2 expression in cells expressing the Csf-1 receptor (a protein characteristically expressed by macrophages and dendritic cells). We discovered that following polarization, macrophages collected from the bone marrow of these mice have an altered distribution of M1 and M2 sub-populations, which are macrophage sub-populations known to differ in their migratory capabilities. Furthermore, we have shown that M1 and M2 subpopulations of bone marrow-derived macrophages from normal mice differ in their expression of APLP2. Thus, APLP2 is influential in macrophage biology, and we have created a novel mouse model for defining its specific contributions in mice treated with HDACi that influence macrophage biology. Conclusions: Based on the data that we have acquired, we are well positioned to fully explore both the impact of HDACi drugs on macrophage/dendritic cell populations in a syngeneic neuroblastoma mouse model, and to define the role of APLP2 in the function of these cell populations in the context of neuroblastoma.https://digitalcommons.unmc.edu/chri_forum/1000/thumbnail.jp

Amyloid Precursor-like Protein 2 Expression Increases during Pancreatic Cancer Development and Shortens the Survival of a Spontaneous Mouse Model of Pancreatic Cancer.

In the United States, pancreatic cancer is a major cause of cancer-related deaths. Although substantial efforts have been made to understand pancreatic cancer biology and improve therapeutic efficacy, patients still face a bleak chance of survival. A greater understanding of pancreatic cancer development and the identification of novel treatment targets are desperately needed. Our analysis of gene expression data from patient samples showed an increase in amyloid precursor-like protein 2 (APLP2) expression within primary tumor epithelium relative to pancreatic intraepithelial neoplasia (PanIN) epithelial cells. Augmented expression of APLP2 in primary tumors compared to adjacent stroma was also observed. Genetically engineered mouse models of spontaneous pancreatic ductal adenocarcinoma were used to investigate APLP2\u27s role in cancer development. We found that APLP2 expression intensifies significantly during pancreatic cancer initiation and progression in the LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre (KPC) mouse model, as shown by immunohistochemistry analysis. In studies utilizing pancreas-specific heterozygous and homozygous knockout of APLP2 in the KPC mouse model background, we observed significantly prolonged survival and reduced metastatic progression of pancreatic cancer. These results demonstrate the importance of APLP2 in pancreatic cancer initiation and metastasis and indicate that APLP2 should be considered a potential therapeutic target for this disease

Amyloid precursor-like protein 2 (APLP2) affects the actin cytoskeleton and increases pancreatic cancer growth and metastasis.

Amyloid precursor-like protein 2 (APLP2) is aberrantly expressed in pancreatic cancer. Here we showed that APLP2 is increased in pancreatic cancer metastases, particularly in metastatic lesions found in the diaphragm and intestine. Examination of matched human primary tumor-liver metastasis pairs showed that 38.1% of the patients had positive APLP2 expression in both the primary tumor and the corresponding liver metastasis. Stable knock-down of APLP2 expression (with inducible shRNA) in pancreatic cancer cells reduced the ability of these cells to migrate and invade. Loss of APLP2 decreased cortical actin and increased intracellular actin filaments in pancreatic cancer cells. Down-regulation of APLP2 decreased the weight and metastasis of orthotopically transplanted pancreatic tumors in nude mice