Circular RNA sterile alpha motif domain containing 4A contributes to cell 5-fluorouracil resistance in colorectal cancer by regulating the miR-545-3p/6-phosphofructo-2-kinase/fructose-2,6-bisphosphataseisotype 3 axis

Abstract

Colorectal cancer (CRC) is one of the most fatal cancers in the world. Circular RNA sterile alpha motif domain containing 4A (circSAMD4A) was found to be highly expressed in CRC and promoted the tumorigenesis of CRC. However, the role of circSAMD4A in 5-fluorouracil (5-Fu) resistance of CRC is yet to be clarified. This study is designed to investigate the function of circSAMD4A in 5-Fu resistance of CRC and its potential molecular mechanism. Quantitative real-time PCR was used to detect the expression levels of circSAMD4A, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase isotype 3 (PFKFB3) mRNA, and miR-545-3p, and western blot was used to detect the protein expression. For functional analysis, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay, colony formation/5-ethynyl-2′-deoxyuridine assay, flow cytometry analysis, and glycolysis metabolism analysis were used to assess the capacities of cell viability, proliferation, apoptosis, and glycolysis in 5-Fu–resistant cells of CRC. The dual-luciferase reporter assay was used to verify the interaction between miR-545-3p and circSAMD4A or PFKFB3. Xenograft tumor model was established to confirm the biological role of circSAMD4A in 5-Fu resistance of CRC in vivo. CircSAMD4A was upregulated in 5-Fu–resistant CRC tissues and cells. Functionally, circSAMD4A knockdown inhibited the proliferation and glycolysis mechanism but promoted apoptosis in 5-Fu–resistant cells of CRC. CircSAMD4A was identified as a molecular sponge of miR-545-3p to upregulate PFKFB3 expression. Mechanistically, circSAMD4A knockdown-induced 5-Fu sensitivity was mediated by miR-545-3p/PFKFB3 axis. Moreover, circSAMD4A knockdown improved 5-Fu sensitivity of CRC in vivo. CircSAMD4A contributed to 5-Fu resistance of CRC cells partly through upregulating PFKFB3 expression by sponging miR-545-3p, providing a possible circRNA-targeted therapy for CRC.

Circular RNA circADAM9 Promotes Inflammation, Oxidative Stress, and Fibrosis of Human Mesangial Cells via the Keap1-Nrf2 Pathway in Diabetic Nephropathy

“…Bioinformatic prediction and verification of dual luciferase reporter assay and RNA pull-down assay showed miR-545-3p as a potential miRNA target for circADAM9. Published studies have shown that miR-545-3p could be sequestered by some circRNAs to alleviate the malignant development of cancers, such as lung 29 30 31 and colorectal cancers 32 33 . The current study found reduced expression of miR-545-3p in patients with DN, and the protective effects of circADAM9 suppression in HG-induced HMCs were reversed upon miR-545-3p silencing.…”

The Crosstalk and Clinical Implications of CircRNAs and Glucose Metabolism in Gastrointestinal Cancers

“…As another common anti-cancer drug, 5-FU is incorporated into DNA or RNA due to its similarity with the pyrimidines that are fundamental components of these molecules, leading to cell death and inhibiting cancer progression [ 121 ]. Increased expression of circSAMD4A in CRC [ 122 ] and circNRIP1 in GC [ 79 ] contribute to 5-FU resistance by upregulating glycolysis. Therefore, targeting these circRNAs may overcome this type of drug resistance in GI cancers.…”

Emerging role of non-coding RNAs in glucose metabolic reprogramming and chemoresistance in colorectal cancer

“…Besides, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase isotype 3 (PFKFB3) is a pivotal enzyme for glucose metabolism. Gao Y and the colleagues have found circSAMD4A could facilitate the expression of PFKFB3 and promote glycolysis by sponging miR-545-3p ( 83 ). Moreover, PKM2 is another crucial enzyme for glycolysis in cancer.…”

“…Some dysregulated circRNAs participate in regulating chemoresistance and glycolysis in CRC, such as circSAMD4A ( 83 ) and ciRS-122 ( 81 ). CircSAMD4A contributes to 5-Fu resistance via targeting miR-545-3p/PFKFB3 and regulating glycolysis of CRC cells, while knockdown of circSAMD4A improves the sensitivity of 5-Fu ( 83 ).…”

“…Some dysregulated circRNAs participate in regulating chemoresistance and glycolysis in CRC, such as circSAMD4A ( 83 ) and ciRS-122 ( 81 ). CircSAMD4A contributes to 5-Fu resistance via targeting miR-545-3p/PFKFB3 and regulating glycolysis of CRC cells, while knockdown of circSAMD4A improves the sensitivity of 5-Fu ( 83 ). Exosomes-derived ciRS-122 is capable of promoting glycolysis and making chemosensitive-CRC cells transform into chemoresistant-CRC cells via miR-122/PKM2 axis ( 81 ).…”