GPD1 inhibits the carcinogenesis of breast cancer through increasing PI3K/AKT-mediated lipid metabolism signaling pathway

Abstract

Glycerol 3-phosphate dehydrogenase 1 (GPD1) acts as a tumor suppressor in various types of cancer. However, the mechanisms of GPD1 anti-tumor remain unclear in breast cancer. This study aims to explore the function and clinical relevance of GPD1 in breast cancer. We confirmed that GPD1 inhibited the ability of proliferation, migration, and invasion in GPD1 overexpression breast cancer cells by CCK-8, wound healing, and Transwell assays, respectively. We found that GPD1 overexpression activated the lipid synthesis pathway and PI3K/AKT signaling pathway. The inhibitory effect of GPD1 on breast cancer cells was also weakened after treatment with LY294002, a PI3K/AKT pathway inhibitor. These results indicated that GPD1 suppressed the carcinogenesis of breast cancer through increasing PI3K/AKT-mediated lipid signaling pathways. Meanwhile, we detected that the relationship between GPD1 level and survival rate presents a positive correlation in breast cancer patients from the Cancer Genome Atlas (TCGA) database. Therefore, GPD1 can be a prognostic biomarker and target in developing therapeutic strategies for breast cancer patients.

Keywords: Biomarker; Breast cancer; Glycerol 3-phosphate dehydrogenase 1; Lipid metabolism; PI3K/AKT signaling pathway.

Fig. 1

The GPD1 mRNA expression levels of breast cancer patients in TCGA. (A) GPD1 expression levels in breast invasive carcinoma and normal tissues. (B) GPD1 expression levels in different subtypes of breast cancer, including Luminal, HER2 positive, and TNBC. (C) GPD1 expression levels in four pathological stages of breast cancer.

Fig. 2

GPD1 overexpression inhibited cell proliferation, migration, and invasion. (A) The mRNA expression levels of GPD1 in breast cancer tissues (n = 50). (B–C) GPD1 expression in breast cancer cells and normal breast cells. (D) Cell proliferation as determined by CCK-8. (E-F) Cell migration as determined by wound healing assay. (G) Cell invasion as determined by Transwell assay. The data are presented as the mean ± SD. A two-tailed Student's t-test was used. *p < 0.05, **p < 0.01, ***p < 0.001.

Fig. 3

Overexpression of GPD1 up-regulated lipid metabolism. (A) The volcano map of different metabolism. Green and red dots indicated down- and up-regulated DMs, respectively. The abscissa represented the logarithmic value of the fold change (log₂FC). The ordinate represented the VIP value. (B) The KEGG enrichment pathway of DMs. The abscissa represented the rich factor corresponding to each pathway. The color and size of the bubble points indicated the p-value and the number of enriched DMs, respectively. (C) The mRNA expression levels of the key lipid metabolic genes. (D) The contents of free fatty acids. Data are shown as the mean ± SD (n = 5, *p < 0.05, **p < 0.01, ***p < 0.001). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 4

GPD1 overexpression activated PI3K/AKT signaling pathway. (A–B) The protein expression levels of PI3K, p-AKT, AKT, p-GSK3β, GSK3β, PTEN, and GAPDH after GPD1 overexpression. (C-D) The protein expression levels of PI3K, AKT, p-AKT, p-GSK3β, GSK3β, and GAPDH after transfection LY294002 inhibitor. (E) The ability of cell proliferation after transfection LY294002 inhibitor. Densitometric analyses of the band intensity ratios for GPD1/GAPDH, PI3K/GAPDH, PTEN/GAPDH, p-AKT/AKT, and p-GSK3β/GSK3β. Data are shown as the mean ± SD (n = 3, *p < 0.05, **p < 0.01, ***p < 0.001).

Fig. 5

The clinical significance of GPD1 in different populations of breast cancers. (A) The overall survival at different expression levels of GPD1. (B) The Kaplan-Meier survival analysis between the GPD1 expression level and menopause status, including pre-menopause, peri-menopause, and post-menopause. (C) GPD1 expression levels in different breast cancer races.

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