GFAT1 is highly expressed in cancer stem cells of pancreatic cancer

Abstract

Background: Cancer stem cells (CSCs) play pivotal roles in the growth, invasion, metastasis, and chemoresistance of pancreatic cancer (PC). The current characterization of CSCs in PC is not complete.Glutamine-fructose-6-phosphate transaminase 1 (GFAT1) is a key enzyme that regulates the hexosamine pathway (HP), in which it not only controls glucose influx but also catalyzes the reaction to form glucosamine 6-phosphate. Recently, it was reported that GFAT1 is highly expressed in PC. However, the relevance of this high expression of GFAT1, especially its association with cancer stemness, has not been well defined and is thus addressed in the current study.Methods: GFAT1 levels were determined in PC from a public database and assessed by bioinformatics tools. GFAT1 expression in CD133 + and CD44 + CSCs in PC was analyzed by reverse transcriptionquantitative polymerase chain reaction (RT-qPCR) and immunostaining on cytospun cells after flow cytometry-based cell sorting. GFAT1 + cells were separated from GFAT1 − cells by transfection of PC cell lines with a designed plasmid that expressed red fluorescent protein (RFP) under a GFAT1 promoter. Tumor sphere formation, tumor growth, tumor cell invasion, cell migration, and the resistance to gemcitabineinduced apoptosis were determined in GFAT1 + vs. GFAT1 − PC cells.Results: GFAT1 levels were significantly upregulated in PC compared to the adjacent non-PC tissue.There were significantly more GFAT1 + cells in the CD133 + population than in the CD133 − population, and similarly, there were significantly more GFAT1 + cells in the CD44 + population than in the CD44 − population.Compared to GFAT1 − PC cells, GFAT1 + PC cells generated significantly more tumor spheres in culture, appeared to be more invasive and migratory, and were significantly more resistant to gemcitabine-induced cell apoptosis.Conclusions: GFAT1 is highly expressed in CSCs among PC cells and may be crucial for PC growth, metastasis, and chemoresistance.

The Effect of Intratumor Heterogeneity in Pancreatic Ductal Adenocarcinoma Progression and Treatment

“…Additionally, the in vitro expression of GFAT1 was linked to gemcitabine resistance. 33 In patients with PDAC, stem cell markers CD44, CD133, and ALDH1 were present at higher levels in samples from individuals who underwent neoadjuvant chemoradiotherapy compared with those who did not receive this treatment. [42][43][44][45] This suggests that cells expressing these markers are more resistant to the chemoradiotherapy.…”

“…In further studies, additional markers for PCSCs have been identified, such as cathepsin B, glutamine-fructose-6-phosphate transaminase 1 (GFAT), doublecortin, acetylated α-tubulin, and aldehyde dehydrogenase 1 (ALDH1) 30–33 . The fact that several markers were found, but not always coexpressed, suggests that pancreatic adenocarcinoma may contain multiple populations of CSCs (Fig.…”

“…This resistance is thought to be caused by higher expression of the ABCG3 gene, lower levels of microRNA-200 (miRNA-200), or Chk1 (T. Yin et al, 2011; Y. E. Zhang et al, 2012; Zhao et al, 2016). Additionally, the in vitro expression of GFAT1 was linked to gemcitabine resistance 33 . In patients with PDAC, stem cell markers CD44, CD133, and ALDH1 were present at higher levels in samples from individuals who underwent neoadjuvant chemoradiotherapy compared with those who did not receive this treatment 42–45 .…”

The role of metabolic reprogramming in pancreatic cancer chemoresistance

“…Silencing GFAT1 reduces O-GlcNAc levels and inhibits PC cell growth ( Jia et al, 2020 ; Yamamoto et al, 2022 ). Both CD133+ or CD44 + PC stem cells have higher GFAT1 levels and are more resistant to GEM-induced apoptosis than cells with corresponding marker loss ( Wang Z. et al, 2022 ). Stomatin like protein 2 is a mitochondrial-associated protein upregulated after GEM stimulation.…”

On a sugar high: Role of O-GlcNAcylation in cancer

“…This increase in HBP activity and UDP-GlcNAc level could be a result of an increased influx of metabolites such as glucose and glutamine into the HBP pathway ( 20 ). However, other reports also suggested that the expression of key enzymes of the HBP is elevated in cancer, which might result in the elevated activity of the HBP and potentially contribute to drive tumor growth ( 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ).…”