Immunohistochemical studies on expression of human vascular smooth muscle myosin heavy chain isoforms in normal mammary glands, benign mammary disorders and mammary carcinomas

Abstract

The expression of myosin in normal and diseased mammary glands of 199 Japanese women was evaluated immunohistochemically by the avidin-biotin peroxidase complex method using antibodies to three human smooth muscle myosin heavy chain isoforms derived from the vascular smooth muscle: myosin SM1 is expressed consistently from fetal stage to adulthood, myosin SM2 appears only in well-differentiated smooth muscle after birth, and myosin SMemb is more abundant in embryonic aortas. SM1 was expressed in myoepithelial cells of normal mammary glands and fibrocystic diseases and in myoepithelial-like tumor cells in the basal layer of fibroadenomas and phyllodes tumors. SM2 was expressed only in the myoepithelial cells of mammary glands in breastfeeding women. SMemb was expressed more intensely in the cytoplasm of luminal epithelial cells in larger fibroadenomas (P< 0.01), or in the cytoplasm of carcinoma cells in invasive ductal carcinomas with metastasized lymph nodes (P< 0.001) and in those of higher histological grade (P<0.0001). Multivariate logistic analysis showed a significant correlation only between the expression of SMemb and histological grade (P< 0.0001), which is a prognostic factor of mammary carcinomas. These findings suggested the possible prognostic value of SMemb.

Distribution of p63, a novel myoepithelial marker, in fine-needle aspiration biopsies of the breast

“…In routine cytologic preparations, the precise identification of myoepithelial cells plays a major role in the diagnostic assessment of several types of breast lesions. These cells are a constituent of the normal basal layer of the breast lobules and ducts and usually are lost during malignant progression 1, 2, 4–14, 17–20. However, identification of myoepithelial cells in breast biopsies and FNAB specimens sometimes is difficult using Papanicolaou‐stained or Giemsa‐stained preparations 1, 4, 12…”

“…Several antibodies have been employed as myoepithelial markers, including S‐100 protein, α‐smooth muscle actin, calponin, myosin heavy chain, and maspin 1, 2, 4–12. Recently, p63, a p53 homologue, has been characterized as a reliable marker of myoepithelial cells of breast lobules and ducts 13, 14.…”

The significance of focal myoepithelial cell layer disruptions in human breast tumor invasion: a paradigm shift from the “protease-centered” hypothesis

“…It is a useful marker in the differentiation between ME cells and spindle cells of the stroma, and also between non-invasive and invasive lesions [27,28]. However, calponin staining in ME cells may occasionally be discontinuous or absent in in situ ductal lesions [29].…”

Dual usages of single Wilms' tumor 1 immunohistochemistry in evaluation of breast tumors: A preliminary study of 30 cases1

“…These biomarkers could be classified into two main categories: (1). structure-specific proteins, which include smooth muscle actin, smooth muscle myosin heavy chain, Calponin, H-caldesmon, P-cadherin, and Cytokeratins 5, 7, 14, and 17 [5][6][7][8][9][10][11][12][13][14][15][16][17]; (2). non-structural molecules, which include p63, p73, Maspin, 14-3-3 Sigma, Neuropilin-1, CD 10, and S100 [18][19][20][21][22][23][24][25].…”