Yong-Sub Byun

Fludioxonil induced the cancer growth and metastasis via altering epithelial-mesenchymal transition via an estrogen receptor-dependent pathway in cellular and xenografted breast cancer models.

Fludioxonil is an antifungal agent used in agricultural applications that is present at measurable amounts in fruits and vegetables. In this study, the effects of fludioxonil on cancer cell viability, epithelial–mesenchymal transition (EMT), and metastasis were examined in MCF‐7 clonal variant breast cancer cell (MCF‐7 CV cells) with estrogen receptors (ERs). MCF‐7 CV cells were cultured with 0.1% DMSO (control), 17β‐estradiol (E2; 1 ×10−9 M, positive control), or fludioxonil (10−5−10−8 M). MTT assay revealed that fludioxonil increased MCF‐7 CV cell proliferation 1.2 to 1.5 times compared to the control, while E2 markedly increased the cell proliferation by about 3.5 times. When the samples were co‐treated with ICI 182,780 (10−8 M), an ER antagonist, fludioxonil‐induced cell proliferation was reversed to the level of the control. Protein levels of cyclin E1, cyclin D1, Snail, and N‐cadherin increased in response to fludioxonil as the reaction to E2, but these increases were not observed when fludioxonil was administered with ICI 182,780. Moreover, the protein level of p21 and E‐cadherin decreased in response to treatment with fludioxonil, but remained at the control level when co‐treated with ICI 182,780. In xenografted mouse models transplanted with MCF‐7 CV cells, fludioxonil significantly increased the tumor mass formation by about 2.5 times as E2 did when compared to vehicle (0.1% DMSO) during the experimental period (80 days). Immunohistochemistry revealed that the protein level of proliferating cell nuclear antigen (PCNA), Snail, and cathepsin D increased in response to fludioxonil as the reaction to E2. These results imply that fludioxonil may have a potential to induce growth or metastatic behaviors of breast cancer by regulation of the expression of cell cycle‐, EMT‐, and metastasis‐related genes via the ER‐dependent pathway.

Fryl deficiency is associated with defective kidney development and function in mice

FRY like transcription coactivator (Fryl) gene located on chromosome 5 is a paralog of FRY microtubule binding protein (Fry) in vertebrates. It encodes a protein with unknown functions. Fryl gene is conserved in various species ranging from eukaryotes to human. Although there are several reports on functions of Fry gene, functions of Fryl gene remain unclear. A mouse line containing null mutation in Fryl gene by gene trapping was produced in this study for the first time. The survival and growth of Fryl−/− mice were observed. Fryl gene expression levels in mouse tissues were determined and histopathologic analyses were conducted. Most Fryl−/− mice died soon after birth. Rare Fryl−/− survivors showed growth retardation with significantly lower body weight compared to their littermate controls. Although they could breed, more than half of Fryl−/− survivors died of hydronephrosis before age 1. No abnormal histopathologic lesion was apparent in full-term embryo or adult tissues except the kidney. Abnormal lining cell layer detachments from walls of collecting and convoluted tubules in kidneys were apparent in Fryl−/− neonates and full-term embryos. Fryl gene was expressed in renal tubular tissues including the glomeruli and convoluted and collecting tubules. This indicates that defects in tubular systems are associated with Fryl functions and death of Fryl−/− neonates. Fryl protein is required for normal development and functional maintenance of kidney in mice. This is the first report of in vivo Fryl gene functions. Impact statement FRY like transcription coactivator (Fryl) gene is conserved in various species ranging from eukaryotes to human. It expresses a protein with unknown function. We generated a Fryl gene mutant mouse line and found that most homozygous mice died soon after their birth. Rare Fryl−/− survivors showed growth retardation with significantly lower body weight compared to their littermate controls. Although they could breed, more than half of Fryl−/− survivors died of hydronephrosis before age 1. Full-term mutant embryos showed abnormal collecting and convoluted tubules in kidneys where Fryl gene was expressed. Collectively, these results indicate that Fryl protein is required for normal development and functional maintenance of kidney in mice. To the best of our knowledge, this is the first report on in vivo Fryl gene functions.

Effect of dioxin and 17β‐estradiol on the expression of cytochrome P450 1A1 gene via an estrogen receptor dependent pathway in cellular and xenografted models

Cytochrome P450 (CYP) 1A1 plays a major role in the metabolic activation of procarcinogens to carcinogens via aryl hydrocarbon receptor (AhR) pathway. Especially, 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) is known as an agonist of AhR. In estrogen responsive cancers, 17β‐estradiol (E2) may influence on AhR dependent expression of CYP1 family via the interaction between estrogen receptor (ER) and AhR. In the present study, the effect of E2/ER on the expression of AhR and CYP1A1 genes was investigated for MCF‐7 clonal variant (MCF‐7 CV) breast cancer cells expressing ER. In reverse transcription‐PCR and Western blot analysis, mRNA expression level of AhR was not altered, but its protein expression level was increased by TCDD or E2. The transcriptional and translational levels of CYP1A1 appeared to be increased by TCDD or E2. The increased expression of AhR and CYP1A1 induced by E2 was restored to the control level by the co‐treatment of ICI 182,780, indicating that E2 induced the protein expression levels of AhR and CYP1A1 like TCDD via an ER dependent pathway. In an in vivo xenograft mouse model transplanted with MCF‐7 CV cells, the protein expression levels of AhR and CYP1A1 of tumor masses were also increased by E2 or TCDD. Taken together, these results indicate that E2 may promote AhR dependent expression of CYP1A1 via ER dependent pathway in MCF‐7 CV cells expressing ER in the absence of TCDD, an agonist of AhR. The relevance of E2 and ER in CYP1A1 activation of estrogen responsive cancers may be targeted for developing more effective cancer treatments.