miRNA levels are associated with body mass index in endometrial cancer and may have implications for therapy

Abstract

Endometrial cancer (EC) is the most prevalent gynecological cancer in high-income countries. Its incidence is skyrocketing due to the increase in risk factors such as obesity, which represents a true pandemic. This study aimed to evaluate microRNA (miRNA) expression in obesity-related EC to identify potential associations between this specific cancer type and obesity. miRNA levels were analyzed in 84 EC patients stratified based on body mass index (BMI; ≥30 or <30) and nine noncancer women with obesity. The data were further tested in The Cancer Genome Atlas (TCGA) cohort, including 384 EC patients, 235 with BMI ≥30 and 149 with BMI <30. Prediction of miRNA targets and analysis of their expression were also performed to identify the potential epigenetic networks involved in obesity modulation. In the EC cohort, BMI ≥30 was significantly associated with 11 deregulated miRNAs. The topmost deregulated miRNAs were first analyzed in 84 EC samples by single miRNA assay and then tested in the TCGA dataset. This independent validation provided further confirmation about the significant difference of three miRNAs (miR-199a-5p, miR-449a, miR-449b-5p) in normal-weight EC patients versus EC patients with obesity, resulting significantly higher expressed in the latter. Moreover, the three miRNAs were significantly correlated with grade, histological type, and overall survival. Analysis of their target genes revealed that these miRNAs may regulate obesity-related pathways. In conclusion, we identified specific miRNAs associated with BMI that are potentially involved in modulating obesity-related pathways and that may provide novel implications for the clinical management of obese EC patients.

Keywords: BMI; endometrial cancer; miRNA; obesity; personalized medicine.

FIGURE 1

Global microRNA (miRNA) expression analysis. (A) Global views of miRNA expression using principal component analysis of the 24 samples analyzed via the TaqMan Low density array. Each triangle or circle represents the collective expression of all miRNAs in each sample. Each color is indicative of a different group (EC⁻/Ob⁺, samples from noncancer patients who were obese; EC⁺/Ob⁺, samples from endometrial cancer (EC) patients who were obese). (B) Volcano plot showing the relationship between fold change and statistical significance. Green and red dots represent differentially expressed mRNAs with statistical significance. (C) Heatmap showing differential miRNA expression in the EC group (EC⁺/Ob⁺) versus the control group (EC⁻/Ob⁺). Each row represents an miRNA and each column represents a sample.

FIGURE 2

Global microRNA (miRNA) expression analysis. (A) Principal component analysis of 40 samples analyzed via the TaqMan Low density array. Each triangle represents the collective expression of all miRNAs in one sample. Each color is indicative of a different group (EC⁺/Ob⁻, endometrial cancer [EC] samples with BMI < 30; EC⁺/Ob⁺, EC samples with BMI ≥ 30). (B) Heatmap showing differential miRNA expression in EC patients who were (EC⁺/Ob⁺) or were not (EC⁺/Ob⁻) obese. Blue indicates lower expression and red represents higher expression. Each row represents an miRNA and each column represents a sample. (C) Expression levels of the four topmost significant miRNAs in EC patients stratified by BMI.

FIGURE 3

(A) Analysis of miR‐199a‐5p, miR‐449a, miR‐449b‐5p, and miR‐2110 in TCGA endometrial cancer cohort stratified based on BMI ≥ or <30. miRNA levels are expressed as log2 expression: *P < 0.05, **P < 0.01, ***P < 0.001. (B) Expression levels of miR‐199a, miR‐449a, and miR‐449b‐5p in the TCGA cohort, stratifying the patients as normal weight (N; BMI < 25, n = 83), overweight (OW; 30 > BMI ≥ 25, n = 67), and obese (OB; BMI ≥ 30, n = 234). miRNA levels are expressed as log₂ expression.

FIGURE 4

Potential miRNA–mRNA networks. miR‐449a and miR‐449b‐5p, belonging to the same miRNA family, were upregulated in EC⁺/Ob⁺ patients while their mRNA targets were downregulated. Each arrow indicates an upregulated target gene, while the dashed line represents a protein–protein association according to the String database.