Differential Expression of Myoepithelial Markers in Salivary, Sweat and Mammary Glands

Abstract

Myoepithelial cells (MECs) are contractile elements showing a combined epithelial and smooth muscle phenotype. Among the numerous immunohistochemical markers employed to detect MECs, smooth muscle actin (SMA) is the most widely used. Recently, other markers of smooth muscle differentiation have been demonstrated in MECs, such as calponin, heavy caldesmon (h-caldesmon), and smooth muscle myosin heavy chain (SMM-HC). In the present study normal salivary, mammary, and sweat glands have been studied with four markers of smooth muscle differentiation (SMA, calponin, h-caldesmon, and SMM-HC). The four markers were differentially expressed in the various types of glands. In parotid glands MECs mainly expressed calponin and caldesmon; in submandibular and in cutaneous apocrine and eccrine glands, MECs strongly expressed SMA, calponin, and caldesmon; in minor salivary glands all four markers were equally strongly expressed; and in mammary glands SMA, calponin, and SMM-HC were present both in periductal and periacinar MECs while caldesmon was present in periductal MECs only. In addition to MECs, SMA stained stromal myofibroblasts, sometimes hampering the identification of MECs. Among the other markers, calponin stained only rare stromal myofibroblasts, while caldesmon and SMM-HC were confined to MECs. In conclusion, these latter markers are very useful for identifying MECs. It is suggested that the differential expression of smooth muscle contractile proteins might reflect different functions of MECs in the various sites. Int J Surg Pathol 8(1):29-37, 2000

Structural components of the nonstriated contractile apparatuses in the Caenorhabditis elegans gonadal myoepithelial sheath and their essential roles for ovulation

“…Smooth muscles are present in both vertebrates and invertebrates and play a variety of functions (Somlyo and Somlyo, 1994). Myoepithelial cells are often found in the outer layer of exocrine glands and have characteristics of both smooth muscle and epithelial cells (Lazard et al, 1993;Foschini et al, 2000;Furuse et al, 2005). Myofibroblasts are present in many organs and express several sarcomeric proteins (Mayer and Leinwand, 1997;Walker et al, 2001;Rice and Leinwand, 2003).…”

p63: A Novel Myoepithelial Cell Marker in Canine Mammary Tissues

“…In particular, as a result of the combined epithelial and contractile phenotype of these cells, the immunohistochemical markers available are based on their cytoskeletal components and on the presence of specific actin subtypes. 1,23 Monoclonal antibodies directed against alpha-smooth muscle actin (ASMA) and cytokeratin 14 (CK14) are known to immunoreact with myoepithelial cells, both in human breast tissue 7,11,15,26,31 and in the canine mammary gland. 3,[32][33][34] p63, a recently characterized p53 homologue, 35 is necessary to maintain a stem cell epithelial population, and it is consistently expressed in basal cells of several types of multilayered epithelia 14,16,21,36 and in myoepithelial cells of the human breast 1 and is considered a possible marker of stem or reserve cells.…”

Comparative Immunohistochemical Study of P63, SMA, CD10 and Calponin in Distinguishing In Situ from Invasive Breast Carcinoma

“…Normal breast glands and ducts are composed of 3 cell types that express different subsets of proteins: luminal, basal, and myoepithelial [1,2]. The luminal and basal cell types express different cytokeratins (CKs); myoepithelial cells (MECs) express basal cell-type CKs and other more specific markers, such as smooth muscle actin, calponin, and p63.…”

“…Myoepithelial cells (MEC) are contractile elements found in salivary, sweat, and mammary glands that show a combined smooth muscle and epithelial phenotype [1]. Normal breast glands and ducts are composed of 3 cell types that express different subsets of proteins: luminal, basal, and myoepithelial [1,2].…”