The potential of epigenetic therapy to target the 3D epigenome in endocrine-resistant breast cancer.

Three-dimensional (3D) epigenome remodeling is an important mechanism of gene deregulation in cancer. However, its potential as a target to counteract therapy resistance remains largely unaddressed. Here, we show that epigenetic therapy with decitabine (5-Aza-mC) suppresses tumor growth in xenograft models of pre-clinical metastatic estrogen receptor positive (ER+) breast tumor.

DNA methylation is required to maintain both DNA replication timing precision and 3D genome organization integrity.

DNA replication timing and three-dimensional (3D) genome organization are associated with distinct epigenome patterns across large domains. However, whether alterations in the epigenome, in particular cancer-related DNA hypomethylation, affects higher-order levels of genome architecture is still unclear. Here, using Repli-Seq, single-cell Repli-Seq, and Hi-C, we show that genome-wide methylation loss is associated with both concordant loss of replication timing precision and deregulation of 3D genome organization.

A novel ATM-dependent checkpoint defect distinct from loss of function mutation promotes genomic instability in melanoma.

Melanomas have high levels of genomic instability that can contribute to poor disease prognosis. Here, we report a novel defect of the ATM-dependent cell cycle checkpoint in melanoma cell lines that promotes genomic instability. In defective cells, ATM signalling to CHK2 is intact, but the cells are unable to maintain the cell cycle arrest due to elevated PLK1 driving recovery from the arrest.

Targeting the androgen receptor in breast cancer.

The androgen receptor (AR) is expressed in the majority of breast cancer and across the three main breast cancer subtypes. Historically, the oncogenic role of AR has best been described in molecular apocrine breast cancers, an estrogen receptor (ER)-/AR+ subtype which has a steroid response signature similar to that in the ER-positive breast cancer. The signalling effect of AR is likely to be different across breast cancer subtypes, and particularly important is its interaction with ER signalling.

Finally, how histone deacetylase inhibitors disrupt mitosis!

The disruption of normal mitosis by histone deacetylase inhibitors is a significant contributor to the anticancer effects of these drugs. However, the mechanism by which these drugs affect mitosis is poorly understood. A number of recent papers have now thrown considerable light onto how these drugs elicit this very distinctive cell cycle disruption.

Inhibition of histone deacetylase 3 produces mitotic defects independent of alterations in histone H3 lysine 9 acetylation and methylation.

The constitutive heterochromatin of the centromere is marked by high levels of trimethylated histone H3 lysine 9 (H3K9) and binding of the heterochromatin protein 1 (HP1), which are believed to also have an important role in mitosis. Histone deacetylase inhibitors (HDACis) are a class of anticancer agents that affect many cellular processes, including mitosis. Here we examine the mechanism by which these drugs disrupt mitosis.

The histone deacetylase inhibitor MGCD0103 has both deacetylase and microtubule inhibitory activity.

Histone deacetylase inhibitors (HDACis) are currently in trial or are in clinical use for the treatment of a number of tumor types. The clinical efficacy of HDACis can be partly attributed to the modulation of the cell cycle by the HDACis. Here, we have examined the effects of N-(2-aminophenyl)-4-((4-pyridin-3-ylpyrimidin-2-ylamino)methyl)benzamide (MGCD0103), a class I-selective histone deacetylase inhibitor, on the cell cycle and cell killing.