Ki-67/MKI67 is an antigen which is expressed during G1, S, G2, and M phases of the cell cycle (mitotically active cells), but not during G0 phase (resting cells). It is a large protein with expected molecular weight of about 395 kDa, and it has a very complex localization pattern within the nucleus, one which changes during cell cycle progression. During interphase, Ki-67 antigen can be exclusively detected in the nucleus, whereas in mitotic phase, most of Ki67 pool gets relocated to the chromosomal surface. Ki67 undergoes phosphorylation/dephosphorylation during mitosis, is susceptible to proteases and its structure implies that its expression is regulated by proteolytic pathways. Ki67 is associated with nucleolar DFC (dense fibrillary component) and its regulation appears to be tightly controlled presumably by precise synthesis and degradation systems involving proteasome/protease complex. It interacts with KIF15 as well as MKI67IP proteins, and due to its association with cell division process, Ki-67 is routinely used as cellular proliferation marker of solid tumors/hematological malignancies in clinical diagnostics, and in experiments involving actively dividing normal or cancerous cells.
Sherman-Baust et al 2014 from National Institute on Aging, USA employed Ki-67/MKI67 antibody for IHC assays on human serous tubal intraepithelial carcinoma (hSTIC, a potential precursor of ovarian high-grade serous carcinoma /HGSC) and mSTICS lesions from fallopian tubes of mogp-TAg transgenic mouse, a genetically engineered ovarian cancer mouse model which expresses the SV40 large T-antigen /TAg under the control of murine mullerian-specific Ovgp-1 promoter. hSTICs as well as mSTICs showed a variety of analogous neoplastic lesions and were found to be highly proliferative as determined through Ki-67 positivity (1). A recent publication from Journal of Hepatology by Rachidi et al. 2015 documented the use of Ki-67/MKI67 antibody for IHC-P analysis of liver sections from WT and gp96-knockout mice. Ki67 expression was considered as an index for proliferation and gp96+ nodules were found to show higher proliferation compared to adjacent gp96- hepatocytes in KO mice or normal hepatocytes of WT mice, establishing gp96/ grp94 as a pro-oncogenic chaperone (2). Our Ki-67/MKI67 antibody was used by Ifkovits and co-workers, 2015 for ICC-IF immunostaining assay on MEFs that were subjected or not to treatment with TGF- beta inhibitor, SB431542, a small molecule capable of increasing the conversion of both MEFs as well as adult cardiac fibroblasts to iCMs (induced cardiomyocytes) up to five folds (3). Tan et al 2015’s team used Ki-67/MKI67 antibody for IHC on Frozen sections of PC3 xenografts that were obtained from mice subjected or not to 24 hours of treatments with pantoprazole/PTP, docetaxel/DOC or PTP+DOC (docetaxel-treatment after pretreatment with pantoprazole). Ki67 was used as a marker of cell proliferation for the evaluation of effectiveness of the tested drugs (4). Ki67 is a well-tested marker of proliferating cells that has been documented in thousands of publications implicating clinical and preclinical studies.
Novus Biologicals offers a variety of high quality Ki-67/MKI67 products for your research needs including: Ki67 Antibodies, Peptides and Proteins and RNAi.
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By: Subhash Gangar
