Abstract
BackgroundAlthough an increasing number of histone demethylases have been identified and biochemically characterized, their biological functions largely remain uncharacterized, particularly in the context of human diseases such as cancer. We investigated the role of KDM5B, a JmjC histone demethylase, in human carcinogenesis. Quantitative RT-PCR and microarray analyses were used to examine the expression profiles of histone demethylases in clinical tissue samples. We also examined the functional effects of KDM5B on the growth of cancer cell lines treated with small interfering RNAs (siRNAs). Downstream genes and signal cascades induced by KDM5B expression were identified from Affymetrix Gene Chip experiments, and validated by real-time PCR and reporter assays. Cell cycle-dependent characteristics of KDM5B were identified by immunofluorescence and FACS.ResultsQuantitative RT-PCR analysis confirmed that expression levels of KDM5B are significantly higher in human bladder cancer tissues than in their corresponding non-neoplastic bladder tissues (P < 0.0001). The expression profile analysis of clinical tissues also revealed up-regulation of KDM5B in various kinds of malignancies. Transfection of KDM5B-specific siRNA into various bladder and lung cancer cell lines significantly suppressed the proliferation of cancer cells and increased the number of cells in sub-G1 phase. Microarray expression analysis indicated that E2F1 and E2F2 are downstream genes in the KDM5B pathway.ConclusionsInhibition of KDM5B may affect apoptosis and reduce growth of cancer cells. Further studies will explore the pan-cancer therapeutic potential of KDM5B inhibition.
Highlights
An increasing number of histone demethylases have been identified and biochemically characterized, their biological functions largely remain uncharacterized, in the context of human diseases such as cancer
In order to find demethylases that contribute to human carcinogenesis, we examined the expression profiles of several proteins containing a JmjC histone demethylase domain in clinical tissues and found that expression levels of KDM5B were significantly up-regulated, compared with their corresponding normal tissues, in many types of cancer
KDM5B expression is up-regulated in clinical cancer tissues We first examined expression levels of five jumonji histone demethylase genes included in JARID family, KDM5A (JARID1A), KDM5B (JARID1B), KDM5C (JARID1C), KDM5D (JARID1D) and JARID2, in a small subset of clinical bladder cancer samples and found a significant difference in expression levels between normal and cancer cells only for the KDM5B gene
Summary
An increasing number of histone demethylases have been identified and biochemically characterized, their biological functions largely remain uncharacterized, in the context of human diseases such as cancer. We investigated the role of KDM5B, a JmjC histone demethylase, in human carcinogenesis. Histone methylation plays an important dynamic role in regulating chromatin structure. We previously reported that SMYD3, a histone methyltransferase, stimulates cell proliferation through its methyltransferase activity and plays a crucial role in human carcinogenesis [6,7,8,9,10]. In order to find demethylases that contribute to human carcinogenesis, we examined the expression profiles of several proteins containing a JmjC histone demethylase domain in clinical tissues and found that expression levels of KDM5B were significantly up-regulated, compared with their corresponding normal tissues, in many types of cancer Dysfunction of histone methylation status was indicated to contribute to human carcinogenesis [11,12,13], the relationship between abnormal histone demethylation and human carcinogenesis is still largely unclear.
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