Epigenetic Dysregulation of KCNK9 Imprinting and Triple-Negative Breast Cancer.

Genomic imprinting is an inherited form of parent-of-origin specific epigenetic gene regulation that is dysregulated by poor prenatal nutrition and environmental toxins. KCNK9 encodes for TASK3, a pH-regulated potassium channel membrane protein that is overexpressed in 40% of breast cancer. However, KCNK9 gene amplification accounts for increased expression in <10% of these breast cancers. Here, we showed that KCNK9 is imprinted in breast tissue and identified a differentially methylated region (DMR) controlling its imprint status. Hypomethylation at the DMR, coupled with biallelic expression of KCNK9, occurred in 63% of triple-negative breast cancers (TNBC). The association between hypomethylation and TNBC status was highly significant in African-Americans (p = 0.006), but not in Caucasians (p = 0.70). KCNK9 hypomethylation was also found in non-cancerous tissue from 77% of women at high-risk of developing breast cancer. Functional studies demonstrated that the KCNK9 gene product, TASK3, regulates mitochondrial membrane potential and apoptosis-sensitivity. In TNBC cells and non-cancerous mammary epithelial cells from high-risk women, hypomethylation of the KCNK9 DMR predicts for increased TASK3 expression and mitochondrial membrane potential (p < 0.001). This is the first identification of the KCNK9 DMR in mammary epithelial cells and demonstration that its hypomethylation in breast cancer is associated with increases in both mitochondrial membrane potential and apoptosis resistance. The high frequency of hypomethylation of the KCNK9 DMR in TNBC and non-cancerous breast tissue from high-risk women provides evidence that hypomethylation of the KNCK9 DMR/TASK3 overexpression may serve as a marker of risk and a target for prevention of TNBC, particularly in African American women.

Communication around palliative care principles and advance care planning between oncologists, children with advancing cancer and families.

BACKGROUND: In medical oncology, palliative care principles and advance care planning are often discussed later in illness, limiting time for conversations to guide goal-concordant care. In pediatric oncology, the frequency, timing and content of communication about palliative care principles and advance care planning remains understudied. METHODS: We audio-recorded serial disease re-evaluation conversations between oncologists, children with advancing cancer and their families across the illness trajectory until death or 24 months from last disease progression. Content analysis was conducted to determine topic frequencies, timing and communication approaches. RESULTS: One hundred forty one disease re-evaluation discussions were audio-recorded for 17 patient-parent dyads with advancing cancer. From 2400 min of recorded dialogue, 119 min (4.8%) included discussion about palliative care principles or advance care planning. Most of this dialogue occurred after frank disease progression. Content analysis revealed distinct communication approaches for navigating discussions around goals of care, quality of life, comfort and consideration of limiting invasive interventions. CONCLUSIONS: Palliative care principles are discussed infrequently across evolving illness for children with progressive cancer. Communication strategies for navigating these conversations can inform development of educational and clinical interventions to encourage earlier dialogue about palliative care principles and advance care planning for children with high-risk cancer and their families.