Oxygen Levels Do Not Determine Radiation Survival of Breast Cancer Stem Cells

For more than a century oxygen has been known to be one of the most powerful radiosensitizers. However, despite decades of preclinical and clinical research aimed at overcoming tumor hypoxia, little clinical progress has been made so far. Ionizing radiation damages DNA through generation of free radicals. In the presence of oxygen these lesions are chemically modified, and thus harder to repair while hypoxia protects cells from radiation (Oxygen enhancement ratio (OER)). Breast cancer stem cells (BSCSs) are protected from radiation by high levels of free radical scavengers even in the presence of oxygen. This led us to hypothesize that BCSCs exhibit an OER of 1. Using four established breast cancer cell lines (MCF-7, T47D, MDA-MB-231, SUM159PT) and primary breast cancer samples, we determined the number of BCSCs using cancer stem cell markers (ALDH1, low proteasome activity), compared radiation clonogenic survival and mammosphere formation under normoxic and hypoxic conditions, and correlated these results to the expression levels of key members of the free radical scavenging systems. The number of BCSCs increased with increased aggressiveness of the cancer. This correlated with increased radioresistance (SF8Gy), and decreasing OERs. When cultured as mammospheres, breast cancer cell lines and primary samples were highly radioresistant and not further protected by hypoxia (OER∼1)

Blastic plasmacytoid dendritic cell neoplasm: evolving insights in an aggressive hematopoietic malignancy with a predilection of skin involvement

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) derived from precursors of plasmacytoid dendritic cells is a very rare, unique, and highly aggressive immature hematopoietic malignancy, more frequently occurring among healthy elderly adults. BPDCN can be characterized by a striking predilection for cutaneous involvement, which is often detected incidentally by dermatologists and is difficult to clinically distinguish it from other primary skin lesions and histologically from leukemia/lymphoma cutis. Thus, histological diagnosis of cutaneous biopsies is crucial to correctly classify this entity. Most patients eventually progress to acute myeloid leukemia and are generally not curable. Here, we present 2 cases of classic BPDCN and discuss the origin of tumor and literature-based characteristic clinical and morphological features, evolving immunomarkers, and molecular genetic aspects of this neoplasm