Depletion of histone demethylase KDM5B inhibits cell proliferation of hepatocellular carcinoma by regulation of cell cycle checkpoint proteins p15 and p27
Wang et al. Journal of Experimental & Clinical Cancer Research
Depletion of histone demethylase KDM5B inhibits cell proliferation of hepatocellular carcinoma by regulation of cell cycle checkpoint proteins p15 and p27
Dong Wang 0 1
Sheng Han 0 1
Rui Peng 0 2
Chenyu Jiao 1
Xing Wang 1
Xinxiang Yang 1
Renjie Yang 1
Xiangcheng Li 1
0 Equal contributors
1 Liver Transplantation Center, Key Laboratory of Living Donor Liver Transplantation, Ministry of Public Health, First Affiliated Hospital of Nanjing Medical University , 300 Guangzhou Road, Nanjing 210029 , China
2 Department of General Surgery, Nanjing Medical University Affiliated Cancer Hospital, Cancer Institute of Jiangsu Province , Nanjing , China
Background: KDM5B is a jmjc domain-containing histone demethylase which remove tri-, di-, and monomethyl groups from histone H3 lysine 4 (H3K4). KDM5B has been determined as an oncogene in many malignancies. However, its expression and role in hepatocellular carcinoma (HCC) remain unknown. Methods: We detected the expression of KDM5B in HCC tissues and cell lines. Cell proliferation was performed to reveal the role of KDM5B depletion on HCC cells both in vivo and in vitro. Flow cytometry was used to analyze the cell cycle and chip analysis was conducted to determine the direct target of KDM5B. Results: KDM5B is frequently up-regulated in HCC specimens compared with adjacent normal tissues and its expression level was significantly correlated with tumor size, TNM stage, and Edmondson grade. Moreover, KaplanMeier survival analysis showed that patients with high levels of KDM5B expression had a relatively poor prognosis. Knockdown of KDM5B notably inhibits HCC cell proliferation both in vivo and in vitro via arresting the cell cycle at G1/S phase partly through up-regulation of p15 and p27. Further molecular mechanism study indicates that silencing of KDM5B promotes p15 and p27 expression by increasing histone H3K4 trimethylation in their promoters. Conclusions: KDM5B could be a potentially therapeutic target, which provides a rationale for the development of histone demethylase inhibitors as a strategy against HCC.
KDM5B; HCC; Cell cycle; p15; p27
Background
Mounting evidence indicates that epigenetic alterations
contribute significantly to the initiation and progression
of multiple human malignancies, including
hepatocellular carcinoma [
1–3
]. As an important type of histone
modification, Histone methylation plays a central role in
regulating chromatin dynamics and transcription. This
modification has been linked to transcriptional
activation or repression of gene expression, depending on the
specific residues that become methylated and the state
of methylation [
4
]. In general, lysine methylation on
H3K4, H3K36, H3K79 is associated with gene activation,
whereas lysine methylation on H3K9, H3K27, H4K20 is
linked to gene silencing [
5
]. Histone lysine methylation
is reversibly controlled by histone demethylases and
methyltransferases. Growing studies suggest that a
number of histone demethylases are dysregulated in tumors
and can serve as oncoproteins [
6–9
].
Liver cancer is the sixth most common malignant
disease worldwide but the third most frequent cause of
cancer-related death, with only 5 % of patients surviving
more than 5 years. In fact, about half of these cases and
deaths occur in China. Hepatocellular carcinoma (HCC)
represents the major histological subtype of primary liver
cancer, accounting for 70 to 85 % of the total liver cancer
worldwide, and its molecular etiology is heterogeneous
[
10
]. Numerous studies of molecules and signalling
pathways related to the development of HCC have been
identified, yet the deep mechanisms underlying the
oncogenesis and cancer progression of HCC remain poorly
understood [
11–15
]. Therefore, a histone demethylase
that promotes HCC tumorigenesis could be an attractive
novel target for drug discovery. However, little is known
about the role of histone demethylases in HCC.
KDM5B is a jmjc domain-containing histone
demethylase, which belongs to KDM5 family. KDM5B was first
identified and characterized in 1999 when Lu found its
overexpression in human breast-cancer cell lines and
primary breast carcinomas [
16
]. Mammalian KDM5B
shows a restricted expression pattern in normal adult
tissues and is primarily present in the testis and brain
[
17, 18
]. However, KDM5B levels were found to be
upregulated in a variety of human cancers such as bladder
cancer, [19] lung cancer, [
20
] colorectal cancer, [
21
]
prostate cancer, [
22, 23
] gastric cancer, [24] glioma, [
25
]
ovarian cancer [
26
] and malignant melanoma [
27
]. Since
KDM5B probably acts as a transcriptional regulator by
its ability to remove tri-, di-, and monomethyl groups
from H3K4, several cancer-associated genes regulated by
KDM5B have been identified, including tumor
suppressor gene BRCA1 that is repressed by KDM5B and
transcription factors E2F1 and E2F2 that are up-regula (...truncated)