Treatment with RT was associated with longer LRFS, DFS, and OS in patients with early-stage breast cancer and detectable CTCs. These results are hypothesis generating; a prospective trial evaluating CTC-based management for RT after breast-conserving surgery in women with early-stage breast cancer is warranted.

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Rationale Mice lacking the EF-hand Ca2+ sensor S100A1 display endothelial dysfunction due to distorted Ca2+ activated NO generation. Objective To determine the pathophysiological role of S100A1 in endothelial cell (EC) function in experimental ischemic revascularization. Methods and Results Patients with chronic critical lower limb ischemia (CLI) showed almost complete loss of S100A1 expression in hypoxic tissue. Ensuing studies in S100A1 knockout (SKO) mice subjected to femoral artery resection (FAR) unveiled insufficient perfusion recovery and high rates of autoamputation. Defective in vivo angiogenesis prompted cellular studies in SKO ECs and human ECs with siRNA-mediated S100A1 knockdown demonstrating impaired in vitro and in vivo proangiogenic properties (proliferation, migration, tube formation), and attenuated vascular endothelial growth factor (VEGF)- and hypoxia-stimulated eNOS activity. Mechanistically, S100A1 deficiency compromised eNOS activity in ECs both by interrupted stimulatory S100A1/eNOS interaction and PKC hyperactivation that resulted in inhibitory eNOS phosphorylation and enhanced VEGF-receptor 2 (VEGFR2) degradation with attenuated VEGF signaling. Ischemic SKO tissue recapitulated the same molecular abnormalities with insufficient in vivo NO generation. Unresolved ischemia entailed excessive VEGF accumulation in SKO mice with aggravated VEGFR2 degradation and blunted in vivo signaling through the proangiogenic PI3K/Akt/eNOS cascade. NO supplementation strategies rescued defective angiogenesis and salvaged limbs in SKO mice post-FAR. Conclusions Our study shows for the first time downregulation of S100A1 expression in patients with CLI and identifies S100A1 as critical for EC function in postnatal ischemic angiogenesis. These findings link its pathological plasticity in CLI to impaired neovascularization prompting further studies to probe S100A1’s microvascular therapeutic potential.

Calcium (Ca2+) signaling plays a key role in a wide range of physiological functions including control of cardiac and skeletal muscle performance. To assure a precise coordination of both temporally and spatially transduction of intracellular Ca2+ oscillations to downstream signaling networks and target operations, Ca2+ cycling regulation in muscle tissue is conducted by a plethora of diverse molecules. Ca2+ S100A1 is a member of the Ca2+-binding S100 protein family and represents the most abundant S100 isoform in cardiac and skeletal muscle. Early studies revealed distinct expression patterns of S100A1 in healthy and diseased cardiac tissue from animal models and humans. Further elaborate investigations uncovered S100A1 protein as a basic requirement for striated muscle Ca2+ handling integrity. S100A1 is a critical regulator of cardiomyocyte Ca2+ cycling and contractile performance. S100A1-mediated inotropy unfolds independent and on top of βAR-stimulated contractility with unchanged βAR downstream signaling. S100A1 has further been detected at different sites within the cardiac sarcomere indicating potential roles in myofilament function. More recently, a study reported a mitochondrial location of S100A1 in cardiomyocytes. Additionally, normalizing the level of S100A1 protein by means of viral cardiac gene transfer in animal heart failure models resulted in a disrupted progression towards cardiac failure and enhanced survival. This brief review is confined to the physiological and pathophysiological relevance of S100A1 in cardiac and skeletal muscle Ca2+ handling with a particular focus on its potential as a molecular target for future therapeutic interventions.

Prolactin controls the development and function of milk-producing breast epithelia but also supports growth and differentiation of breast cancer, especially luminal subtypes. A principal signaling mediator of prolactin, Stat5, promotes cellular differentiation of breast cancer cells in vitro, and loss of active Stat5 in tumors is associated with anti-estrogen therapy failure in patients. In luminal breast cancer progesterone induces a cytokeratin-5 (CK5)-positive basal cell-like population. This population possesses characteristics of tumor stem cells including quiescence, therapy-resistance, and tumor-initiating capacity. Here we report that prolactin counteracts induction of the CK5-positive population by the synthetic progestin R5020 in luminal breast cancer cells both in vitro and in vivo. CK5-positive cells were chemoresistant as determined by four-fold reduced rate of apoptosis following docetaxel exposure. Progestin-induction of CK5 was preceded by marked up-regulation of BCL6, an oncogene and transcriptional repressor critical for the maintenance of leukemia-initiating cells. Knockdown of BCL6 prevented induction of CK5-positive cell population by progestin. Prolactin suppressed progestin-induced BCL6 through Jak2-Stat5 but not Erk- or Akt-dependent pathways. In premenopausal but not postmenopausal patients with hormone receptor-positive breast cancer, tumor protein levels of CK5 correlated positively with BCL6, and high BCL6 or CK5 protein levels were associated with unfavorable clinical outcome. Suppression of progestin-induction of CK5-positive cells represents a novel pro-differentiation effect of prolactin in breast cancer. The present progress may have direct implications for breast cancer progression and therapy since loss of prolactin receptor-Stat5 signaling occurs frequently and BCL6 inhibitors currently being evaluated for lymphomas may have value for breast cancer.

Therapy resistance remains a major problem in estrogen receptor-α (ERα)-positive breast cancer. A subgroup of ERα-positive breast cancer is characterized by mosaic presence of a minor population of ERα-negative cancer cells expressing the basal cytokeratin-5 (CK5). These CK5-positive cells are therapy resistant and have increased tumor-initiating potential. Although a series of reports document induction of the CK5-positive cells by progestins, it is unknown if other 3-ketosteroids share this ability. We now report that glucocorticoids and mineralocorticoids effectively expand the CK5-positive cell population. CK5-positive cells induced by 3-ketosteroids lacked ERα and progesterone receptors, expressed stem cell marker, CD44, and displayed increased clonogenicity in soft agar and broad drug-resistance in vitro and in vivo. Upregulation of CK5-positive cells by 3-ketosteroids required induction of the transcriptional repressor BCL6 based on suppression of BCL6 by two independent BCL6 small hairpin RNAs or by prolactin. Prolactin also suppressed 3-ketosteroid induction of CK5+ cells in T47D xenografts in vivo. Survival analysis with recursive partitioning in node-negative ERα-positive breast cancer using quantitative CK5 and BCL6 mRNA or protein expression data identified patients at high or low risk for tumor recurrence in two independent patient cohorts. The data provide a mechanism by which common pathophysiological or pharmacologic elevations in glucocorticoids or other 3-ketosteroids may adversely affect patients with mixed ERα+/CK5+ breast cancer. The observations further suggest a cooperative diagnostic utility of CK5 and BCL6 expression levels and justify exploring efficacy of inhibitors of BCL6 and 3-ketosteroid receptors for a subset of ERα-positive breast cancers.

Radiation oncology (RO) is a dynamic and rapidly changing field. Residents are uniquely positioned to identify issues relevant to graduate medical education and the future workforce. As the elected members of the Executive Committee for the Association of Residents in Radiation Oncology (ARRO), we communicate with the larger RO community about the issues that residents identify as being the most pressing. ARRO recently sent a brief survey to registered American Society for Radiation Oncology (ASTRO) members-in-training (N Z 710) asking them to rank in order any (or all) of 14 specified issues that "concern[ed them] as radiation oncologist[s]." Responses were received from 179 individuals from April 4th through May 10th (response rate Z 25.2%). The top 3 concerning issues (Fig. 1), by rank order, were the job market (91%), the American Board of Radiology (ABR) qualifying (written) examinations (85%), and residency expansion (84%). Other issues identified by trainees included oral boards, declining reimbursement, variability in training programs, and fellowship expansion. Additional free-text concerns were submitted by 90 trainees. The top 2 themes included clinical relevance of board certification examinations (n Z 17) and trust in leadership (n Z 11). Here, we will briefly discuss the top 3 issues. Job Market The principal concern identified by residents was the job market (Fig. 1). Not only did 91% of residents rank the job market as "a concerning issue," but 72% ranked it as 1 of the

Post-mastectomy radiotherapy (PMRT) yields improvements in both locoregional control and overall survival (OS) for women with T1-2 N1 breast cancer. The value of PMRT in this population has been questioned given advances in systemic therapy. The 21-gene recurrence score (RS) assay was evaluated as a predictor of OS among women with T1-2 N1 breast cancer who received or did not receive PMRT. An observational cohort study was performed on women with T1-2 N1 estrogen receptor-positive breast cancer from the National Cancer Database (NCDB) and, as a validation cohort, from the surveillance, epidemiology, and end results (SEER) registry who underwent mastectomy and were evaluated for RS. Multivariable parametric accelerated failure time models were used to estimate associations of RS and PMRT with OS using propensity score-adjusted matched cohorts. In both the NCDB ( = 7,332) and SEER ( = 3,087) cohorts, there was a significant interaction of RS and PMRT with OS ( = 0.009 and = 0.03, respectively). PMRT was associated with longer OS in women with a low RS [NCDB: time ratio (TR) = 1.70; 95% CI (confidence interval), 1.30-2.22; < 0.001; SEER: TR = 1.85; 95% CI, 1.33-2.57; < 0.001], but not in women with an intermediate RS (NCDB: TR = 0.89; 95% CI, 0.69-1.14; = 0.35; SEER: TR = 0.84; 95% CI, 0.62-1.14; = 0.26), or a high RS (NCDB: TR = 1.10; 95% CI, 0.91-1.34; = 0.33; SEER: TR = 0.79; 95% CI, 0.50-1.23; = 0.28). Longer survival associated with PMRT was limited to women with a low RS. PMRT may confer the greatest OS benefit for patients at the lowest risk of distant recurrence. These results caution against omission of PMRT among women with low RS. .