Smooth muscle myosin heavy chain / SMMHC

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Stains & CD markers
Smooth muscle myosin heavy chain / SMMHC

Author: Rebecca Obeng, M.D.

Last author update: 1 January 2017

Last staff update: 24 September 2024

Copyright: 2017-2024, PathologyOutlines.com, Inc.

PubMed search: SMMHC

Table of Contents

Cite this page: Obeng R. Smooth muscle myosin heavy chain / SMMHC. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stainssmmhc.html. Accessed December 25th, 2024.

Definition / general

The MYH11 gene (Chromosome 16) encodes a smooth muscle myosin protein (SMMHC) that is a subunit of a hexameric protein involved in contraction, the conversion of chemical energy into mechanical energy via ATP hydrolysis, and G protein coupled receptors / GPCR signaling
- Alternative splicing generates different isoforms (Int J Biochem Cell Biol 2006;38:1862)
Fusion between core binding factor beta (CBF-beta) with SMMHC (CBFbeta-SMMHC; Inv(16)(p13q22)) is present in nearly all acute myeloid leukemia M4 eosinophilia subtype (AML M4Eo)
Useful for differentiating between benign and malignant lesions (e.g. breast and lung lesions)

Essential features

Expressed in the cytoplasm and cell membrane of myoepthelial and smooth muscle cells
Useful for the differentiation of benign and malignant breast and lung (bronchoalveolar carcinoma) lesions
Associated diseases
- Inv(16)(p13q22) with SMMHC fusion gene seen in nearly all acute myeloid leukemia M4 eosinophilia subtype (Nat Genet 1999;23:144; Cancer Cell 2006;9:57)
- Rare autosomal dominant mutations in the MYH11 gene seen in familial aortic aneurysm and dissection and patent ductus arteriosis (Nat Genet 2006;38:343; Hum Mol Genet 2007;16:2453; Int J Cardiol 2013;165:314; Hum Genome Variat 2015;2:15028)

Terminology

Myosin heavy chain 11, myosin 11, myosin heavy chain, smooth muscle isoform, MYH11, SMHC, SMMHC

Sites

Expressed in cytoplasm and cell membrane of myoepithelial and smooth muscle cells

Pathophysiology

Acute myeloid leukemia of M4 eosinophilia subtype: the CBFbeta-SMMHC fusion protein inhibits myeloid differentiation and represses RUNX1; it also induces changes in gene expression in hematopoietic cells (Nat Genet 1999;23:144; J Cell Biochem 2010;110:1039)
Aortic aneurysm and dissection: medial degeneration with smooth muscle cell disarray and hyperplasia in the medial layer of the aorta due to mutations in the MYH11 gene (Nat Genet 2006;38:343; Hum Mol Genet 2007;16:2453; Curr Atheroscler Rep 2012;14:219)

Diagnosis

SMMHC IHC staining useful to evaluate restenosis in peripheral artery disease (Atherosclerosis 2016;251:226)
SMMHC expression is decreased in diverticular disease (J Gastroenterol 2014;49:1241)

Laboratory

Studies suggest serum levels of SMMHC are significantly higher in patients with acute aortic dissection and may be a good biomarker for early diagnosis (Heart Lung 2015;44:205; J Am Coll Cardiol 2010;56:1535)

Microscopic (histologic) description

Cytoplasmic and membranous staining in normal myoepithelial and smooth muscle cells
Nuclear staining in acute myeloid leukemic cells with Inv(16)

Microscopic (histologic) images

Contributed by Rebecca Obeng, M.D.

SMMHC staining myoepithelial cells

Images hosted on other servers:

Positive stains:

Colon

Endometrium

Various images

Cytology description

Positive immunohistochemical staining in spindle cells between epithelial cells or along the edges of epithelial cells in benign breast lesions; negative staining in invasive breast carcinomas except for vascular smooth muscle cells (Diagn Cytopathol 1999;20:203)

Positive stains

Myoepithelial and smooth muscle cells
CBFbeta-SMMHC IHC staining in AML-M4Eo (nuclear stain) (Am J Surg Path 2006 30:1436)

Negative staining

SMMHC can be a sensitive and specific marker for myoepithelial cells of the breast, helping to distinguish benign from malignant lesions (negative for SMMHC) (J Clin Pathol 2004:57:625)
Staining may be reduced or patchy in carcinoma in situ (CIS) (Arch Pathol Lab Med 2014;138:1629)
Invasive papillary carcinomas are negative (Arch Pathol Lab Med 2011;135:422)

Flow cytometry description

Intracellular staining for CBFbeta-SMMHC can be used for the identification of AML M4Eo leukemic cells (Blood 1998;91:1882)

Molecular / cytogenetics description

Inv(16)(p13q22) or t(16:16)(p13q22) leads to fusion of CBFbeta and SMMHC that can be detected by fluorescent in situ hybridization

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