The in vivo cell kinetics in breast carcinogenesis

The ambiguous salivary myoepithelial cells

Salivary gland neoplasms present with a diverse histological pattern which is mainly because of the presence of specialized myoepithelial cells (MECs). These are contractile epithelial cells with smooth muscle like properties. They have been also noticed in mammary glands, lacrimal glands, prostate gland, and the sweat glands and have varied functions. MECs play an important role in the histogenesis of many salivary gland tumors. Knowledge of MECs leads to a better understanding of the histological diversity of salivary gland neoplasms. This article reviews the physiology, histology, identification and role of these cells in salivary gland pathology.

Requirement of a myocardin-related transcription factor for development of mammary myoepithelial cells

The mammary gland consists of a branched ductal system comprised of milk-producing epithelial cells that form ductile tubules surrounded by a myoepithelial cell layer that provides contractility required for milk ejection. Myoepithelial cells bear a striking resemblance to smooth muscle cells, but they are derived from a different embryonic cell lineage, and little is known of the mechanisms that control their differentiation. Members of the myocardin family of transcriptional coactivators cooperate with serum response factor to activate smooth muscle gene expression. We show that female mice homozygous for a loss-of-function mutation of the myocardin-related transcription factor A (MRTF-A) gene are unable to effectively nurse their offspring due to a failure in maintenance of the differentiated state of mammary myoepithelial cells during lactation, resulting in apoptosis of this cell population, a consequent inability to release milk, and premature involution. The phenotype of MRTF-A mutant mice reveals a specific and essential role for MRTF-A in mammary myoepithelial cell differentiation and points to commonalities in the transcriptional mechanisms that control differentiation of smooth muscle and myoepithelial cells.

Does Timing of Adjuvant Chemotherapy for Early Breast Cancer Influence Survival?

Purpose: Theoretically, patients with early breast cancer might benefit from starting adjuvant chemotherapy soon after surgery, and this would have important clinical implications. We have addressed this question from a large, single-center database in which the majority of patients received anthracyclines.

Patients and Methods: A total of 1,161 patients from a prospectively maintained database treated with adjuvant chemotherapy for early breast cancer at the Royal Marsden Hospital (London, United Kingdom), including 686 (59%) receiving anthracyclines, were retrospectively analyzed. The disease-free survival (DFS) and overall survival (OS) of the 368 patients starting chemotherapy within 21 days of surgery (group A) were compared with those of the 793 patients commencing chemotherapy ≥ 21 days after surgery (group B). Median follow-up time was 39 months (range, 12 to 147 months).

Results: No significant difference in 5-year DFS was found between the two groups overall (70% for group A v 72% for group B; P = .4) or in any subgroup. Likewise, there was no difference in 5-year OS (82% for group A v 84% for group B; P = .2) or when the interval to the start of chemotherapy was considered as a continuous variable (P = .4).

Conclusion: We have been unable to identify any significant survival benefit from starting adjuvant chemotherapy early after surgery, either overall or in any subset of patients.