Comparison of leucine-rich repeat-containing G protein-coupled receptor 5 expression in different cancer and normal cell lines

Abstract

Abstract. Evaluating the expression of leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) may be useful for predicting the best models and achieving more accurate results in cancer research. Therefore, the aim of the present study was to analyze the LGR5 expression levels in different cell lines. Eight commonly used cell lines were assessed (COS-7, NIH3T3, HEK293, VERO, HeLa, BHK, HepG2 and AGS). All the cell lines were cultured in RPMI-1640 medium contain 10% fetal calf serum at 37˚C in humidified conditions with 5% CO 2 . According to the western blotting results, LGR5 was expressed in all cell lines. Densitometry results of LGR5 expression in the different cell lines showed that high LGR5 expression levels were apparent in BHK, AGS, VERO and NIH3T3 cell lines compared with the other cell lines. The results indicate that for the normal and cancer cell lines, BNK and AGS may be a better choice, respectively, for in vitro cancer studies. IntroductionCancer has become the major cause of mortality in certain countries in the 21st century (1). There are three models for cancer heterogeneity. Tumor heterogeneity is attained through genetic or epigenetic modifications. The stochastic model, as the first model, indicates that all tumor cells potentially are capable of self-renewal or differentiation, and are tumorigenic (2). In the second model, the hierarchical model, which is also known as the cancer stem cell (CSC) model of tumor growth, the ability of self-renew is considered for only a subset of tumor cells; the CSCs. These cells generate committed progenitor cells with limited proliferative potential, which ultimately lead to terminal differentiation (3-5). The third model is known as the complex model and this model suggests that epigenetic changes can potentially influence the tumor cell phenotype and function due to micro-environmental factors, thereby influencing tumor heterogeneity (2).Recently, a new CSC theory, known as tumor stem cells or tumor-initiating cells, has emerged. A CSC was precisely defined by the American Association for Cancer Research in 2006 as a cell within a tumor that has positive susceptibility to self-renew and to reason the heterogeneous progeny of cancer cells that are contained within the tumor (6). The CSC model was previously described for hematological malignancies in 1997 (7).Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) is considered an intestinal stem cell marker (8).LGR5 has a transducer role in the Wnt signaling pathway (9,10). This signaling pathway is well known to be involved in the embryogenesis and carcinogenesis process (11). Also recognized as GPR49, LGR5 is a member of the G protein-coupled receptors, the largest family of cell-surface molecules involved in a signaling pathway. The size of the LGR5 gene is ~144 kb and it is located at position 12q22-q23 of chromosome 12. The LGR5 protein has seven transmembrane domains. Experimental findings showed that this protein in the mature form contains <17 leucine-rich repeats, each comp...

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“…Overexpression of Lgr5 has been shown in intestinal adenomas and in colorectal cancer tissues, and cells with overexpression of Lgr5 act as cancer stem cells to promote tumor growth in colorectal cancer tissues. 35 , 36 , 37 , 38 , 39 , 40 , 41 …”

LGR5 expression and clinicopathological features of the invasive front in the fat infiltration area of pancreatic cancer

“…LGR5 was identified by lineage tracing to be a novel marker for adult stem cells in the small intestine, large intestine, and hair follicles [ 6 ] [ 7 ]. LGR5 is a seven transmembrane receptor [ 8 ] that is a target gene for Wnt/β-catenin signaling [ 7 ]. LGR5 is recognized as a cancer stem cell (CSC) marker for colorectal cancer [ 9 ].…”