Aberrant epigenetic modifications are emerging as potent drivers of tumor initiation and progression. The deregulation of H3K27me3 marks has shown to play an important role in cancer progression in several cancers. The H3K27me3 mark is associated with gene silencing. The reversible nature of these epigenetic aberrations makes them an important target for treating cancer. GSK‐J4 is a histone demethylase inhibitor that inhibits the JMJD3/UTX enzyme, which results in the upregulation of H3K27me3 levels. In this review, the anti‐cancer properties of GSK‐J4 have been summarized, the various molecular pathways targeted, in‐vivo studies, and drug combination studies in different cancer models. GSK‐J4 targeted pathways like apoptosis, cell cycle, invasion, migration, DNA damage repair, metabolism, oxidative stress, stemness, etc. GSK‐J4 is a promising candidate alone and in combination with other conventional anti‐cancer drugs against different cancer types.

Minimizing side effects, overcoming cancer drug resistance, and preventing metastasis of cancer cells are of growing interest in current cancer therapeutics. Phytochemicals are being researched in depth as they are protective to normal cells and have fewer side effects. Hesperetin is a citrus bioflavonoid known to inhibit TGFβ-induced epithelial-to-mesenchymal transition (EMT), migration, and invasion of prostate cancer cells. Targeting epigenetic modifications that cause cancer is another class of upcoming therapeutics, as these changes are reversible. Global H3K27me3 levels have been found to be reduced in invasive prostate adenocarcinomas. Combining a demethylase inhibitor and a known anti-cancer phytochemical is a unique approach to targeting cancer to attain the aforementioned objectives. In the current study, we used an H3K27 demethylase (JMJD3/KDM6B) inhibitor to study its effects on TGFβ-induced EMT in prostate cancer cells. We then gave a combined hesperetin and GSK-J4 treatment to the PC-3 and LNCaP cells. There was a dose-dependent increase in cytotoxicity and inhibition of TGFβ-induced migration and invasion of prostate cancer cells after GSK-J4 treatment. GSK-J4 not only induced trimethylation of H3K27 but also induced the trimethylation of H3K4. Surprisingly, there was a reduction in the H3K9me3 levels. GSK-J4 alone and a combination of hesperetin and GSK-J4 treatment effectively inhibit the important hallmarks of cancer, such as cell proliferation, migration, and invasion, by altering the epigenetic landscape of cancer cells.

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TGFβ expression acts as a biomarker of poor prognosis in prostate cancer. It plays a dual functional role in prostate cancer. In the early stages of the tumor, it acts as a tumor suppressor while at the later stages of tumor development, it promotes metastasis. The molecular mechanisms of action of TGFβ are largely understood through the canonical and non-canonical signal transduction pathways. Our understanding of the mechanisms that establish transient TGFβ stimulation into stable gene expression patterns remains incomplete. Epigenetic marks like histone H3 modifications are directly linked with gene expression and they play an important role in tumorigenesis. In this report, we performed chromatin immunoprecipitation-sequencing (ChIP-Seq) to identify the genome-wide regions that undergo changes in histone H3 Lysine 4 trimethylation (H3K4me3) occupancy in response to TGFβ stimulation. We also show that TGFβ stimulation can induce acute epigenetic changes through the modulation of H3K4me3 signals at genes belonging to special functional categories in prostate cancer. TGFβ induces the H3K4me3 on its own ligands like TGFβ, GDF1, INHBB, GDF3, GDF6, BMP5 suggesting a positive feedback loop. The majority of genes were found to be involved in the positive regulation of transcription from the RNA polymerase II promoter in response to TGFβ. Other functional categories were intracellular protein transport, brain development, EMT, angiogenesis, antigen processing, antigen presentation via MHC class II, lipid transport, embryo development, histone H4 acetylation, positive regulation of cell cycle arrest, and genes involved in mitotic G2 DNA damage checkpoints. Our results link TGFβ stimulation to acute changes in gene expression through an epigenetic mechanism. These findings have broader implications on epigenetic bases of acute gene expression changes caused by growth factor stimulation.

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