The cell proliferation-associated antigen of antibody Ki-67: a very large, ubiquitous nuclear protein with numerous repeated elements, representing a new kind of cell cycle-maintaining proteins.

Abstract

Abstract. The antigen defined by mAb Ki-67 is a human nuclear protein the expression of which is strictly associated with cell proliferation and which is widely used in routine pathology as a "proliferation marker" to measure the growth fraction of cells in human tumors. Ki-67 detects a double band with apparent molecular weights of 395 and 345 kD in immunoblots of proteins from proliferating cells. We cloned and sequenced the full length eDNA, identified two differentially spliced isoforms of mRNA with open reading frames of 9,768 and 8,688 bp encoding for this cell proliferation-associated protein with calculated molecular weights of 358,761 D and 319,508 D, respectively. New mAbs against a bacterially expressed part and a synthetic polypeptide deduced from the isolated eDNA react with the native Ki-67 antigen, thus providing a circle of evidence that we have cloned the authentic Ki-67 antigen eDNA. The central part of the Ki-67 antigen eDNA contains a large 6,845-bp exon with 16 tandemly repeated 366-bp elements, the "Ki-67 repeats", each including a highly conserved new motif of 66 bp, the "Ki-67 motif", which encodes for the epitope detected by Ki-67. Computer analysis of the nucleic acid and the deduced amino acid sequence of the Ki-67 antigen confirmed that the cDNA encodes for a nuclear and short-lived protein without any significant homology to known sequences. Ki-67 antigen-specific antisense oligonucleotides inhibit the proliferation of IM-9 cell line cells, indicating that the Ki-67 antigen may be an absolute requirement for maintaining cell proliferation. We conclude that the Ki-67 antigen defines a new category of cell cycleassociated nuclear nonhistone proteins.

Limited correlation between human thymus and blood NKT cell content revealed by an ontogeny study of paired tissue samples

“…5), our data indicated that virtually no NKT cells in the blood of children, or adults, expressed the Ki67 antigen expressed by proliferating cells (Fig. 5C) [26][27][28]. In contrast, a significant proportion of NKT cells in the thymus were Ki67 + (*5%), suggesting that a proportion of thymus NKT cells are cycling.…”

All-trans retinoic acid (ATRA)-induced apoptosis is preceded by G1 arrest in human MCF-7 breast cancer cells

“…The antigen Ki-67 is a non-histone nuclear protein of unknown function, although its direct role in the maintenance of cell proliferation has been demonstrated by the inhibition of DNA synthesis by specific antisense oligonucleotides for Ki-67 mRNA (Schluter et al, 1993).…”

“…Ki-67 is expressed at relatively low levels in GI and early S-phase; it rapidly accumulates during the second half of S-phase, reaching a peak at GI`M phases and decreases sharply in post-mitotic cells (Gerdes, 1984;Bruno and Darzynkiewicz, 1990). Being expressed in all the cycle phases, Ki-67 is a particularly suitable marker for proliferating cells (Gerdes et al, 1984;Schluter et al, 1993), and it may therefore be preferred in cell kinetic studies to other proliferation markers, such as cyclins, whose expression is limited to well-defined phases or even subphases of the cycle (Gong et al, 1994).…”

Macrophage Infiltration in Tumor Stroma is Related to Tumor Cell Expression of CD163 in Colorectal Cancer

“…Lymphatic and blood vessels are examined by using mouse monoclonal D2-40 antibody (Abcam, Cambridge, UK) and mouse monoclonal anti-CD31 antibody (Dako, Denmark), respectively. These antibodies are well characterized and have been used in many previous studies [27,[34][35][36][37][38][39]. Serial sections of 5 μm were cut from formalin-fixed paraffin-embedded tissue blocks, deparaffinized in xylene and hydrated in a series of graded alcohols (100 %, 95 %, and 70 %).…”