Overexpression of ZFX confers self-renewal and chemoresistance properties in hepatocellular carcinoma

Abstract

Zinc finger protein X-linked (ZFX) is a zinc finger protein of Zfy family, which is highly conserved in vertebrates. This transcriptional regulator is not only highly expressed in embryonic stem cells (ESC) and hematopoietic stem cells, but is also upregulated in a number of human cancers where it is functional related to cell proliferation and survival. Hepatocellular carcinoma (HCC) is highly aggressive cancer that commonly resistant to most chemotherapies and displays stemness characteristics. In this study, we examined the expression of ZFX in HCC and its possible functional implications in liver tumorigenesis. Quantitative RT-PCR analysis showed common overexpressions of ZFX in 51.8% HCC tumors when compared with their adjacent nonmalignant liver (n 5 43/83; p 5 0.004). Inline with the pluripotency role of ZFX, we found silencing of ZFX readily inhibited self-renewal capability (p 5 0.0022), colony formation ability (p < 0.0001) and cell proliferation (p < 0.0001) through G0/G1 cell cycle arrest of HCC cells (p 5 0.0038). In addition, suppression of ZFX sensitized HCC cells to chemotherapeutic agent cisplatin (p < 0.0001). Further investigations suggested that ZFX bind on the promoter of two important mediators, namely Nanog and SOX-2, activating their expressions in HCC (p < 0.0001). Moreover, in vivo xenograft study demonstrated that overexpression of ZFX would promote the tumor growth (p 5 0.031). Taken together, our results show, for the first time, commonly overexpressions of ZFX in HCC, where it likely contributes to the stemness and pluripotent behavior of this highly malignant cancer.Hepatocellular carcinoma (HCC), which accounts for 80-90% of all liver cancers, is the fifth most common cancer and the third leading cause of cancer-related deaths worldwide. 1 HCC is an aggressive cancer with a high mortality rate; often due to being diagnosed at a late stage when curative therapies are least effective. 2 Moreover, most HCC patients show disease recurrence that rapidly progresses to advanced stages. It is general believed that the presence of cancer stem-like features is responsible for chemoresistance and recurrence of HCC. 3-7 ZFX is a zinc finger protein of the Zfy family that is highly conserved among vertebrates. It is a transcriptional factor encoded on the mammalian X chromosome and contains an acidic transcriptional activation domain, a nuclear localization sequence and a DNA binding domain. 8,9 Despite elevated levels are detected in pluripotent embryonic stem cells (ESCs) and hematopoietic stem cells (HSCs) where it is required for maintenance of self-renewal ability, 8 ZFX is also found to be frequently overexpressed in a number of human cancers, including esophageal carcinoma, gastric cancer, prostate cancer, and glioma. 10-13 Common cancer stemness characteristics, including colony-forming ability, acquisition of drug resistance, cell survival, and cancer metastasis have been further proposed to be induced from ZFX in these cancers. In HCC, the role of ZFX however remains unexplored. The ...

Ectopic expression of embryonic stem cell and other developmental genes in cutaneous T-cell lymphoma

“…Overexpression of ZFX contributes to the 'stemness' and pluripotent behavior of cancers. 49,50 Our study further demonstrates that CTCL lesional skin and patient-derived cell lines express other pluripotency ESC markers including CNOT3, KLF4, TBX3, and TRRAP. Detailed description of these genes and their biological activities is provided in Table S1.…”

“…Furthermore, consistent with the above findings, upstream and downstream members of NANOG signaling are also expressed in CTCL. ZFX (Zinc finger protein Xlinked), a transcription factor, is known to transactivate the promoters of NANOG and SOX2, 49,50 while DAX1 (also known as NR0B1) and MTF2 pluripotency markers are induced by NANOG. 39 All of the aforementioned genes are heterogeneously expressed in CTCL lesional skin.…”

Zinc Finger and X-Linked Factor (ZFX) Binds to Human SET Transcript 2 Promoter and Transactivates SET Expression

“…ZFX could also transactivate c-Myc and the MHC class I HLA-A11 promoters in glioma stem cells (GSCs) and Leydig cells [28,29]. Besides, ZFX has been found to be overexpressed in several solid cancers, including breast cancer [30], prostate cancer [31], Acute T-Lymphoblastic and Myeloid Leukemia [32], hepatocellular carcinoma [33] and non-small cell lung carcinoma [34]. Revelation of ZFX-mediated transactivation of SET provides one mechanism by which ZFX may be implicated in multiple cell functions.…”

Zinc finger protein X-linked is overexpressed in colorectal cancer and is associated with poor prognosis

“…Transwell cell invasion assays were performed using Boyden chambers with filter inserts (pore size, 8 µm) coated with 40 µg Matrigel in 24-well plates. Twenty-four hours after transfection with or without siRNA, cells were harvested, and 100 µl serum-free media containing 2x10 5 cells was added into the upper chamber, while 600 µl medium with 20% fetal bovine serum was placed in the lower chamber. Following incubation for 24 h, the cells were fixed in 4% formaldehyde and stained with 0.1% crystal violet in PBS for 30 min at room temperature.…”

“…Previous studies have demonstrated elevated levels of ZFX in pluripotent embryonic and hematopoietic stem cells, which is required for self-renewal ability (3,4). Overexpression of ZFX has also been demonstrated to confer self-renewal capability in hepatocellular carcinoma (5). In addition, previous studies have revealed that ZFX plays a notable role in regulating the transcription of genes necessary for cell proliferation, cell cycle and cell death (6,7).…”