Gene: maps to 2q13-q14 (Nicklin M.J.H. et al, 1994). The gene is composed of seven exons with a primary transcription product length of 7,008 nucleotides. Features of interest within the transcriptional unit include positioned TATA, CAT, and poly-adenylation signals for gene regulation, as well as the signatures of gene duplication via retrotransposition in the form of flanking direct repeats and a genomic poly A tail (Clark B.D. et al., 1986).
mRNA: size: 1.6-1.7 kb.
Protein: a 153-amino acid (aa), 17-kDa polypeptide (mature form), derived from a biologically unactive (Mosley B. et al., 1987) 269-aa, ~35 kDa precursor. IL-1B is the neutral pI=7) form of interleukin 1, a potent mediator of inflammation and immunity. IL-1B shows only distant homology to
IL-1A (26% at the protein level, 45% at the nucleic acid level). The names therefore suggest a relationship that does not really exist. However, in 3D, both forms are spherical proteins devoid of alpha-helical regions, and both forms bind to the same receptor. IL-1B cleavage is suggested to occur through the action of a 45 kDa cysteine protease named IL-1B-converting enzyme (ICE). This enzyme is apparently cell-surface associated and under the control of cell membrane inhibitors. It seems that
ATP binding cassette (ABC) transporter proteins are crucial to IL-1B secretion.
Cell lines:
Tumors:
- IL-1beta content was measured by ELISA in tissue extracts from >200 invasive breast carcinomas and smaller numbers of ductal carcinoma in situ (DCIS) and benign lesions. Immunoreactive IL-1beta was detected in approximately 90% of invasive breast carcinomas. IL-1beta levels were significantly higher in invasive carcinomas than in a group of DCIS and benign lesions. High IL-1beta content in invasive carcinomas was significantly associated with higher contents of
hepatocyte growth factor (HGF),
Von Willebrand factor (VWF), and
TSP1, but not TNF alpha. There was a trend toward higher IL-1beta content in invasive carcinomas with a group of other parameters that suggest a biologically more aggressive tumor (
estrogen receptor negativity, high tumor grade, p53 positivity, and
bcl-2 negativity); and the proportion of invasive tumors with these characteristics was significantly increased in a subgroup of tumors having very high IL-1beta content. There was also a correlation between high IL-1beta content and CD68 positivity, suggesting that macrophages may account for some of the IL-1beta present in human breast carcinoma tissue (Jin L. et al., 1997).
