LMO2 Enhances Lamellipodia/Filopodia Formation in Basal-Type Breast Cancer Cells by Mediating ARP3-Profilin1 Interaction

A comprehensive analysis of LMO2 pathogenic regulatory profile during T-lineage development and leukemic transformation

LMO2 is a well-known leukemic proto-oncogene, its ectopic expression in T-lineage specifically initiates malignant transformation of immature T cells and ultimately causes the onset of acute T-lymphocytic leukemia (T-ALL) in both mouse models and human patients. In this study, we systematically explored the LMO2 performance on the profiles of transcriptome, DNA-binding and protein interactions during T-lineage development in the pre-leukemic stage. Our data indicated that large-scale transcriptional dysregulation caused by LMO2 primarily occurred in DN3 thymocytes, characterized by enriched upregulation of the target genes of typical LMO2 complex, RUNX, ETS and STATs, and ectopic LMO2 primarily targeted to RUNX motifs along with intensive interaction with RUNX1 and H3K4 methyltransferase component ASH2L in this stage. However, binding of LMO2 on specific motifs was largely reduced in the following DP and SP stages, along with gradually disappeared LMO2-RUNX1 and LMO2-ASH2L interactions and less alteration of certain transcriptional factor profiles. Moreover, LMO2 showed relatively less influence on cellular behavior of DN3 thymocyte whereas displayed more prominent effects in DP and SP stages, including promoting Notch signaling and cell cycles. These findings provide a high-resolution landscape of the pathogenic role of LMO2 during T-lineage development in molecular level, and may benefit further clinical investigations for LMO2-associated T-lineage malignancies.

ACTR3 promotes cell migration and invasion by inducing epithelial mesenchymal transition in pancreatic ductal adenocarcinoma

Background

Recurrence and metastasis are the major causes of pancreatic ductal adenocarcinoma (PDAC) mortality after treatment. The underlying molecular mechanism is poorly understood. Actin-related protein 3 (ACTR3) is an important component of the actin-related protein 2/3 complex, which is involved in the regulation of cell motility and epithelial mesenchymal transition (EMT) process. Previously published studies have indicated that ACTR3 expression is upregulated in several types of cancers, and promotes tumor development, including gastric cancer and hepatocellular carcinoma. However, to date, the expression levels and the role of ACTR3 in PDAC are not well understood.

Methods

In the present study, the expression levels of ACTR3 in PDAC tissue and the relationship of ACTR3 expression with clinical prognosis were analyzed by mRNA microarray and bioinformatics. The biological functions and underlying mechanism of ACTR3 in PDAC were examined by a series of assays, including Cell Counting Kit-8 (CCK-8), transwell assay, and Western blotting.

Results

We found that the expression of ACTR3 was significantly increased in PDAC tissues and cell lines. A higher expression of ACTR3 was predictive of poor outcome for patients with PDAC. In vitro, the knockdown of ACTR3 expression significantly inhibited the invasive and migratory capacity of PDAC cells, and altered the distribution of F-actin and the expression of EMT markers.

Conclusions

The findings of our study indicated that ACTR3 promotes cell migration and invasion by inducing EMT in PDAC, which may be a potential therapeutic target and prognostic indicator for PDAC patients.

Biochemical Feature of LMO2 Interactome and LMO2 Function Prospect

Background

LMO2 belongs to the LIM-Only group of LIM domain protein superfamily. It is ubiquitously expressed in different types of tissues and locates either in the nucleus or in the cytoplasm depending on the tissue type. Till now the unique function of LMO2 was considered to be serving as a bridging or blocking molecule that mediates extensive protein-protein interactions. However, the exactly biological features of LMO2 interactome as well as LMO2 function spectrum remain largely unclear.

Material/Methods

In this study, yeast 2-hybrid assay was firstly performed using LMO2 as the bait and the characteristic of LMO2 protein interactome was analyzed according to the yeast 2-hybrid data and other relative biological information primarily using bioinformatic method.

Results

Our data indicated that LMO2 favored interacting with peptides containing β-sheet structure and having relatively unstable confirmation. Moreover, several LMO2 favored interacting domains were identified, including WD40 repeat, coiled-coil, Ankyrin repeat, Zinc finger, PDZ, and SH3, and functions of these domain-containing members were dramatically enriched in some types of cancers.

Conclusions

Our results revealed a LMO2 favored protein-interaction pattern in both secondary structure and domain level, and concentrated LMO2 function in kinds of cytoplasmic metabolism pathways as well as multiple types of cancers.

ARP3 promotes tumor metastasis and predicts a poor prognosis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death worldwide. Therefore, the study of the precise molecular mechanism underlying hepatocarcinogenesis has profound significance. In this study, we found that the expression of ARP3 was significantly up-regulated in HCC tissues and cell lines. Studies in liver cancer specimens showed that the expression of ARP3 is closely related to the pathological grade, distant metastasis and vascular invasion of HCC. According to the results of multivariate analysis, ARP3 is an independent prognostic factor for HCC patients. In vitro, knockdown of ARP3 expression significantly inhibited the invasion and migration of HCC cells and altered the expression of EMT markers. Based on the above conclusions, we conclude that ARP3 may be a potential prognostic indicator and therapeutic target for HCC patients.

A comprehensive function analysis of LMO2 in different breast cancer subtypes

Breast cancer is the most common invasive cancer in women worldwide, and can be subdivided into Luminal A, Luminal B, Her2, and Basal subtype (the PAM50 subtyping system). The lmo2 gene was traditionally recognized as a proto-oncogene in hematopoietic system but its functions in breast cancers remained largely unclear. Based on the Cancer Genome Atlas (TCGA) breast cancer dataset, herein we found that the significantly LMO2-correlated genes in normal or malignant samples were enriched in rather divergent cellular pathways, suggesting the function complexity of LMO2 in breast tissues. Moreover, high LMO2 expression level was found to predict a shorter patient survival in Luminal A type whereas a better outcome in Her2 type. Correspondingly, LMO2 also revealed function diversities in different PAM50 subtypes. In Luminal A type, the LMO2 related genes were primarily enriched in cancer-promoting pathways, including VEGF production, stemness, PPAR signal pathways, MAPK cascade and cell cycle regulation. In Her2 type however, the LMO2 related genes lacked the enrichment on most of the generally cancer-related pathways and were particularly enriched in negative regulation of ErbB pathway as well as MAPK cascade, suggesting a potentially anti-oncogenic role of LMO2 on this subtype. Taken together, this study drew a comprehensive overview of divergent functions of LMO2 on breast cancers, provided additional evidence for the function complexity of LMO2 in solid tumors and suggested the potential usage of LMO2 as a PAM50 subtype dependent biomarker for breast cancer clinic in the precision medicine era.