Purpose In general, tumor cells display a more glycolytic phenotype compared to the corresponding normal tissue. However, it is becoming increasingly clear that tumors are composed of a heterogeneous population of cells. Breast cancers are organized in a hierarchical manner, with the breast cancer stem cells (BCSCs) at the top of the hierarchy. Here, we investigate the metabolic phenotype of BCSCs and their differentiated progeny. In addition, we determine the effect of radiation on the metabolic state of these two cell populations. Methods Luminal, basal, and claudin-low breast cancer cell lines were propagated as mammospheres enriched in BCSCs. Lactate production, glucose consumption and ATP content was compared with differentiated cultures. A metabolic flux analyzer was used to determine the oxygen consumption, extracellular acidification rates, maximal mitochondria capacity and mitochondrial proton leak. The effect of radiation treatment of the metabolic phenotype of each cell population was also determined. Results BCSCs consume more glucose, produce less lactate and have higher ATP content compared to their differentiated progeny. BCSCs have higher maximum mitochondrial capacity and mitochondrial proton leak compared to their differentiated progeny. Radiation treatment enhances the higher energetic state of the BCSCs, while decreasing mitochondrial proton leak. Conclusions Our study indicated that breast cancer cells are heterogeneous in their metabolic phenotypes and BCSCs reside in a distinct metabolic state compared to their differentiated progeny. BCSCs display a reliance on oxidative phosphorylation, while the more differentiated progeny display a more glycolytic phenotype. Radiation treatment affects the metabolic state of BCSCs. We conclude that interfering with the metabolic requirements of BCSCs may prevent radiation-induced reprogramming of breast cancer cells during radiation therapy, thus improving treatment outcome.

Cancer stem cells (CSCs) or tumor-initiating cells, similar to normal tissue stem cells, rely on developmental pathways, such as the Notch pathway, to maintain their stem cell state. One of the regulators of the Notch pathway is Musashi-1, a mRNA-binding protein. Musashi-1 promotes Notch signaling by binding to the mRNA of Numb, the negative regulator of Notch signaling, thus preventing its translation. Cancer stem cells have also been shown to down-regulate their 26S proteasome activity in several types of solid tumors, thus making them resistant to proteasome-inhibitors used as anti-cancer agents in the clinic. Interestingly, the Notch pathway can be inhibited by proteasomal degradation of the Notch intracellular domain (Notch-ICD), therefore down-regulation of the 26S proteasome activity can lead to stabilization of Notch-ICD. Here we present evidence that the down-regulation of the 26S proteasome in CSCs constitutes another level of control by which Musashi-1 promotes signaling through the Notch pathway and maintenance of the stem cell phenotype of this subpopulation of cancer cells. We demonstrate that Musashi-1 mediates the down-regulation of the 26S proteasome by binding to the mRNA of NF-YA, the transcriptional factor regulating 26S proteasome subunit expression, thus providing an additional route by which the degradation of Notch-ICD is prevented, and Notch signaling is sustained.

Purpose Breast cancers are thought to be organized hierarchically with a small number of breast cancer stem cells able to self-renew and to regrow the entire tumor. Importantly, breast cancer stem cells are resistant to established chemotherapeutic agents and relatively resistant to radiation. Self-renewal of breast cancer stem cells is under control of the Notch signaling pathway, which suggests that targeting this pathway could be a novel way of eliminating breast cancer stem cells. The γ-secretase complex controls the final intramembranous cleavage step that activates Notch receptors upon binding of its ligands and specific inhibitors of γ-secretase, which prevent Notch activation, are currently clinically tested against solid cancers in combination with radiotherapy. Radiation activates Notch signaling and therefore, we sought to explore patterns of Notch receptor and ligand expression in response to radiation that could be crucial in defining optimal dosing schemes for γ-secretase inhibitors if combined with radiation. Methods and Materials Using MCF-7 and T47D breast cancer cell lines we used realtime RT-PCR to study the Notch pathway in response to radiation. Results We show that Notch receptor and ligand expression during the first 48 hours after irradiation followed a complex radiation dose-dependent pattern and was most pronounced in mammospheres, enriched for breast cancer stem cells. Additionally, radiation activated the Notch pathway. Treatment with a γ-secretase inhibitor prevented radiation-induced Notch family gene expression and led to a significant reduction in the size of the breast cancer stem cell pool. Conclusions Our results indicate that, if combined with radiation, γ-secretase inhibitors may prevent up-regulation of Notch receptor and ligand family members and thus reduce the number of surviving breast cancer stem cells.

Objectives Vocal fold (VF) scarring, manifested by increased collagen, decreased glycosaminoglycans (GAGs), and disrupted elastic fibers, remains a negative consequence of VF injury or resection. The objective of this study is to compare four reconstructive options after Vf mucosal resection in rabbits. A Cell‐Based Outer Vocal fold Replacement (COVR) using human adipose‐derived mesenchymal stromal cells (hASCs) in fibrin scaffold is directly compared with a decellularized scaffold implant, hASC injection, and resection alone without reconstruction. The primary hypothesis is that the cells‐in‐scaffold construct better reconstitutes the VF structure than either cells or scaffold alone, or than healing by secondary intention. Methods A total of49 rabbits received bilateral VF cordectomy, followed by either COVR implant, decellularized scaffold implant, hASC injection, or no reconstruction (injured control group). Larynges were harvested after 6 weeks. Results Histology demonstrated greater lamina propria thickness, less collagen deposition, and more GAGs in COVR animals versus all other treatment groups. Evidence of persistent human cells was found in about half of the cell‐treated animals. RNA levels of fibrosis pathway and macrophage phenotype markers were statistically unchanged among treatment groups at 6 weeks. Conclusion These data support the efficacy of COVR implantation in restoring VF microstructure in rabbits. The intact COVR was required; isolated components of decellularized scaffold or injected hASC still produced histologic scarring. We propose that the unique bilayered cell structure within fibrin enables controlled matrix remodeling to minimize wound contraction and fibrosis, and to promote GAG deposition. Level of Evidence Basic science study

Primary hyperparathyroidism, often caused by a single adenoma (80-85%) or four-gland hyperplasia (10-15%), can lead to elevated parathyroid hormone (PTH) levels and resultant hypercalcemia. Surgical excision of offending lesions is the standard of care, as the removal of pathologic adenomas reduces PTH and calcium values to baseline. The small size, variable location, and indistinct external features of parathyroid glands can make their identification quite challenging intraoperatively. Our group has developed the dynamic optical contrast imaging (DOCI) technique, a novel realization of dynamic temporally dependent measurements of tissue autofluorescence. In this study, we evaluated the efficacy of using the DOCI technique and normalized steady-state fluorescence intensity data for differentiating types of human parathyroid and thyroid tissues. We demonstrate that the DOCI technique has the capability to distinguish normal parathyroid tissue from diseased parathyroid glands as well as from adjacent healthy thyroid and adipose tissue across 8 different spectral channels between 405nm-600nm (p<0.05). Patient tissue DOCI data was further analyzed with a logistic regression classifier trained across the 8 spectral channels. After computer training, the computer-aided identification was able to accurately locate hypercellular parathyroid tissue with 100% sensitivity and 98.8% specificity within the captured DOCI image.