Expression of fatty acid-binding protein-4 in gastrointestinal stromal tumors and its significance for prognosis

mir-605-3p prevents liver premetastatic niche formation by inhibiting angiogenesis via decreasing exosomal nos3 release in gastric cancer

BACKGROUND

Cancer-induced pre-metastatic niches (PMNs) play a decisive role in promoting metastasis by facilitating angiogenesis in distant sites. Evidence accumulates suggesting that microRNAs (miRNAs) exert significant influence on angiogenesis during PMN formation, yet their specific roles and regulatory mechanisms in gastric cancer (GC) remain underexplored.

METHODS

miR-605-3p was identified through miRNA-seq and validated by qRT-PCR. Its correlation with the clinicopathological characteristics and prognosis was analyzed in GC. Functional assays were performed to examine angiogenesis both in vitro and in vivo. The related molecular mechanisms were elucidated using RNA-seq, immunofluorescence, transmission electron microscopy, nanoparticle tracking analysis, enzyme-linked immunosorbent assay, luciferase reporter assays and bioinformatics analysis.

RESULTS

miR-605-3p was screened as a candidate miRNA that may regulate angiogenesis in GC. Low expression of miR-605-3p is associated with shorter overall survival and disease-free survival in GC. miR-605-3p-mediated GC-secreted exosomes regulate angiogenesis by regulating exosomal nitric oxide synthase 3 (NOS3) derived from GC cells. Mechanistically, miR-605-3p reduced the secretion of exosomes by inhibiting vesicle-associated membrane protein 3 (VAMP3) expression and affects the transport of multivesicular bodies to the GC cell membrane. At the same time, miR-605-3p reduces NOS3 levels in exosomes by inhibiting the expression of intracellular NOS3. Upon uptake of GC cell-derived exosomal NOS3, human umbilical vein endothelial cells exhibited increased nitric oxide levels, which induced angiogenesis, established liver PMN and ultimately promoted the occurrence of liver metastasis. Furthermore, a high level of plasma exosomal NOS3 was clinically associated with metastasis in GC patients.

CONCLUSIONS

miR-605-3p may play a pivotal role in regulating VAMP3-mediated secretion of exosomal NOS3, thereby affecting the formation of GC PMN and thus inhibiting GC metastasis.

Clinicopathological significance and prognostic implication of nuclear fatty acid-binding protein 4 expression in colorectal cancer

This study aimed to evaluate the clinicopathological significance and prognostic role of fatty acid-binding protein 4 (FABP4) expression in colorectal cancer (CRC). Nuclear expression of FABP4 was investigated by immunohistochemistry for FABP4 on 246 human CRC tissues. The correlations between FABP4 expression, and clinicopathological characteristics and survival, was evaluated in patients with CRC. FABP4 was expressed in 91 of the 246 CRC tissues (37.0%). FABP4 expression was significantly correlated with older age, right-sided colon cancer, perineural invasion, higher pT stage, lymph node metastasis, and higher pTNM stage. However, there was no significant correlation between FABP4 expression and sex, tumor size, tumor differentiation, vascular or lymphatic invasion, or distant metastasis. Nuclear FABP4 expression was not significantly correlated with cytoplasmic FABP4 expression (P = 0.412). FABP4 expression was significantly correlated with nuclear pNF-κB expression (P = 0.001), and was significantly higher in CRC with a low immunoscore than in CRC with a high immunoscore (P < 0.001). There were significant correlations between FABP4 expression and worse overall and recurrence-free survival rates (P < 0.001 and P = 0.007, respectively). FABP4 expression was significantly correlated with aggressive tumor behaviors and pathological characteristics. In addition, patients with CRC with FABP4 expression had worse survival rates.

Therapeutic Implications of FABP4 in Cancer: An Emerging Target to Tackle Cancer

Metabolic reprogramming is an emerging hallmark of tumor cells. In order to survive in nutrient-deprived environment, tumor cells rewire their metabolic phenotype to provide sufficient energy and build biomass to sustain their transformed state and promote malignant behaviors. Fatty acid uptake and trafficking is an essential part of lipid metabolism within tumor cells. Fatty acid-binding proteins (FABPs), which belongs to a family of intracellular lipid-binding protein, can bind hydrophobic ligands to regulate lipid trafficking and metabolism. In particular, adipocyte fatty acid binding protein (FABP4), one of the most abundant members, has been found to be upregulated in many malignant solid tumors, and correlated with poor prognosis. In multiple tumor types, FABP4 is critical for tumor proliferation, metastasis and drug resistance. More importantly, FABP4 is a crucial driver of malignancy not only by activating the oncogenic signaling pathways, but also rewiring the metabolic phenotypes of tumor cells to satisfy their enhanced energy demand for tumor development. Thus, FABP4 serves as a tumor-promoting molecule in most cancer types, and may be a promising therapeutic target for cancer treatment.

The Role of Lipid Metabolism in Gastric Cancer

Gastric cancer has been one of the most common cancers worldwide with extensive metastasis and high mortality. Chemotherapy has been found as a main treatment for metastatic gastric cancer, whereas drug resistance limits the effectiveness of chemotherapy and leads to treatment failure. Chemotherapy resistance in gastric cancer has a complex and multifactorial mechanism, among which lipid metabolism plays a vital role. Increased synthesis of new lipids or uptake of exogenous lipids can facilitate the rapid growth of cancer cells and tumor formation. Lipids form the structural basis of biofilms while serving as signal molecules and energy sources. It is noteworthy that lipid metabolism is capable of inducing drug resistance in gastric cancer cells by reshaping the tumor micro-environment. In this study, new mechanisms of lipid metabolism in gastric cancer and the metabolic pathways correlated with chemotherapy resistance are reviewed. In particular, we discuss the effects of lipid metabolism on autophagy, biomarkers treatment and drug resistance in gastric cancer from the perspective of lipid metabolism. In brief, new insights can be gained into the development of promising therapies through an in-depth investigation of the mechanism of lipid metabolism reprogramming and resensitization to chemotherapy in gastric cancer cells, and scientific treatment can be provided by applying lipid-key enzyme inhibitors as cancer chemical sensitizers in clinical settings.

Expression of fatty acid-binding protein-4 in gastrointestinal stromal tumors and its significance for prognosis

Background

Fatty acid‐binding proteins (FABPs) have been found to be involved in tumorigenesis and development. However, the role of FABP4, a member of the FABPs, in GISTs (Gastrointestinal stromal tumors) remains unclear. This study aimed to investigate the expression of FABP4 and its prognostic value in GISTs.

Methods

FABP4 expression in 125 patients with GISTs was evaluated by immunohistochemical analysis of tissue microarrays. The relationship between FABP4 expression and clinicopathological features and prognosis of GISTs was analyzed.

Results

Multiple logistic regression analysis showed that expression of FABP4 correlated with tumor size and mitotic index. Furthermore, FABP4 level, tumor size, mitotic index, and high AFIP‐Miettinen risk were independent prognostic factors in GISTs. The Kaplan‐Meier survival curve showed that the 5‐year survival rate of patients with high‐FABP4 expression GISTs was lower.

Conclusions

These results suggested that high‐FABP4 expression might be a marker of malignant phenotype of GISTs and poor prognosis.