Stains & molecular markers

Topic Completed: 1 March 2016

Minor changes: 22 December 2020

Copyright: 2002-2021,, Inc.

PubMed Search: Ku70[title]

Angela M.Y. Chan, M.Sc.
Page views in 2020: 37
Page views in 2021 to date: 3
Cite this page: Chan A, Enwere E. Ku70. website. Accessed January 16th, 2021.
Definition / general
  • Ku70 is a highly abundant nuclear protein
  • The gene symbol is XRCC6, which stands for "Xray Repair Complementing defective repair in Chinese hamster Cells 6"
  • It is essential for the repair of double - stranded DNA breaks (DSBs) mediated by the classical non - homologous end joining pathway, which is the main DSB repair pathway in mammals (Annu Rev Genet 2013;47:433)
  • Ku70 functions as a heterodimer with Ku80 / Ku86, and together with the DNA dependent protein kinase (DNA - PK) forms the core of DSB repair pathways
  • Ku70 exists as an obligate heterodimer with Ku80 / 86; either protein is unstable in the absence of the other (Mol Cell Biol 1996;16:1519)
  • Ku70 is also involved in V(D)J recombination, which is essential for production of a diverse antibody repertoire (Cell 2013;152:417)
Clinical features
  • High levels of auto - antibodies to Ku70 and Ku80 / 86 have been found in patients with systemic lupus erythematosus, Sjögren syndrome, polymyositis and scleroderma (J Rheumatol 1999;26:563 and Front Biosci 2001;6:D1412)
  • Genetic defects in V(D)J recombination components, including Ku70, result in a severe combined immunodeficiency (SCID) phenotype (Immunity 1997;7:653)
Uses by pathologists
  • No studies have identified germline mutations in human Ku70, suggesting that a functional Ku70 is essential in humans
  • However, somatic mutations exist in cancers such as B cell lymphoma (DNA Repair (Amst) 2014;16:84, J Exp Med 2013;210:1729)
  • Castration improves response of prostate cancer patients to radiotherapy by reducing Ku70 expression in tumors and impairing DSB repair (Sci Transl Med 2015;7:31)
Microscopic (histologic) images

Images hosted on other servers:

IHC analysis of Ku70 / Ku80 in (PDAC) Fig 7

Ku70 expression in normal colon and colon cancer

Gastric cancer

Ku70 detection in
normal human colon,
using a rabbit
polyclonal antibody

Positive staining - normal
  • Ku70 is ubiquitously expressed in nuclei of many cell types at high levels in the stomach, pancreas, colon, kidney, bladder, prostate, placenta, ovary, breast, cerebellum, lung
Positive staining - disease
  • Breast cancer
  • Gastric cancer
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