Organ-Specific Recurrence or Metastatic Pattern of Breast Cancer according to Biological Subtypes and Clinical Characteristics

PURPOSE: We aimed to investigate organ-specific recurrence or the metastatic pattern of breast cancer according to biological subtypes and clinical characteristics. METHODS: We retrospectively analyzed the medical records of 168 patients with recurrent breast cancer who were diagnosed between January 1, 2000 and April 30, 2017. Four biological subtypes were classified according to estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and Ki-67 expression: luminal A, luminal B, HER2-enriched, and triple negative breast cancer (TNBC). To analyze recurrence patterns according to biological subtypes, we accessed clinical variables including age at diagnosis, TNM stage, type of surgery in the breast and axilla, histologic grade, nuclear grade, lymphatic, vascular, and neural invasion, Ki-67 expression and recurrence to distant organs. RESULTS: The biological subtypes of recurrent breast cancer comprised the following luminal A (n=33, 19.6%), luminal B (n=95, 56.5%), HER2 enriched (n=19, 11.3%), and TNBC (n=21, 12.5%). Luminal A (7.7%) and B (6.5%) subtypes were associated with the increased rate of local recurrence compared to HER2-enriched (2.4%) and TNBC subtypes (1.8%) (p=0.005). The bone (53.6%) was the most common metastatic organ, followed by the lung (34.5%), liver (29.8%), brain (17.9%), and other visceral organ (7.7%). Bone metastasis was commonly observed in individuals with luminal B (63.2%), HER2-enriched (57.9%), and luminal A (42.4%) subtypes (p=0.005). Most liver metastases occur in individuals with luminal B (40.0%) and HER2-enriched subtypes (31.6%) (p=0.002). CONCLUSION: Luminal B subtype was commonly observed in individuals with recurrent breast cancer, and the bone is the most common target organ for breast cancer metastasis, followed by the lungs and liver.

Coordinated change of a ratio of methylated H3-Iysine 4 or acetylated H3 to acetylated H4 and DNA methylation is associated with tissue-specific gene expression in cloned pig

Various cell types in higher multicellular organisms are genetically homogenous, but are functionally and morphologically heterogeneous due to the differential expression of genes during development, which appears to be controlled by epigenetic mechanisms. However, the exact molecular mechanisms that govern the tissue-specific gene expression are poorly understood. Here, we show that dynamic changes in histone modifications and DNA methylation in the upstream coding region of a gene containing the transcription initiation site determine the tissue-specific gene expression pattern. The tissue-specific expression of the transgene correlated with DNA demethylation at specific CpG sites as well as significant changes in histone modifications from a low ratio of methylated H3- lysine 4 or acetylated H3-lysine 9, 14 to acetylated H4 to higher ratios. Based on the programmed status of transgene silenced in cloned mammalian ear-derived fibroblasts, the transgene could be reprogrammed by change of histone modification and DNA methylation by inhibiting both histone deacetylase and DNA methylation, resulting in high expression of the transgene. These findings indicate that dynamic change of histone modification and DNA methylation is potentially important in the establishment and maintenance of tissue-specific gene expression.