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Aliases | PIP , GCDFP-15, GCDFP15, GPIP4, Prolactin-induced protein, prolactin induced protein, BRST-2 | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 176720 MGI: 102696 HomoloGene: 1990 GeneCards: PIP | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Prolactin-inducible protein also known as gross cystic disease fluid protein 15 (GCDFP-15), extra-parotid glycoprotein (EP-GP), gp17seminal actin-binding protein (SABP) or BRST2 is a protein that in humans is encoded by the PIP gene. [5] [6] [7] It is upregulated by prolactin and androgens and downregulated by estrogen.
The protein has a physiological function in regulation of water transport mainly in apocrine glands in the axilla, vulva, eyelid and ear canal, serous cells of the submandibular salivary gland, serous cells of the submucosal glands of the bronchi, and accessory lacrimal glands as well as cutaneous eccrine glands. [8] It is also found in amniotic fluid and seminal fluid.
PIP has the ability to bind immunoglobulin G (IgG), IgG-Fc, CD4-T cell receptor suggesting a wide range of immunological functions. [9] [10] PIP also binds to AZGP1. [10] PIP exerts aspartyl proteinase activity able to cleave fibronectin. [11] [12]
PIP can bind different species of bacteria showing highest affinity to streptococci thus playing a role in non-immune defense of the body against pathogenic bacterial strains. [13] [14]
Mitogenic effect of PIP was observed on both normal and malignant breast epithelial cells. [15]
Prolactin induced protein (called GCDFP-15 in this context) in breast cyst fluid or breast tissue serves as marker of both benign and malignant apocrine metaplasia as the protein is not normally expressed in breast tissue. [16] [17] It is characteristic of low grade apocrine carcinoma of the breast, high grade apocrine carcinoma frequently lose expression of this marker. [18] PIP gene expression in breast cancer lines was associated with decreased cell proliferation and invasiveness and an increase of the apoptotic pathway. Many of the genes affected by PIP appear to be regulated by STAT5. [19]
A mitogenic effect of this protein on experimental breast cells lines MCF10A, MCF7, BT474, MDA-MB231 and T47D was detected. [15] Prolactin-induced protein has also been used for identification and detection of disseminated breast cancer cells. [20]
The PIP gene is amplified in some breast cancer lines accounting for some of its overexpression, however additional mechanisms are needed to completely explain its overexpression. [21] In T47D breast cancer cells, androgen receptor and RUNX2 interact to synergistically enhance PIP expression. [22]
In molecular apocrine breast cancer (ER-/AR+) there is a positive feedback loop between androgen receptor and extracellular signal-regulated kinase (ERK) via CREB1 which can be inhibited by anti-androgens. PIP expression is necessary for viability and invasiveness of this subtype of breast cancer. [23]
In ER+ breast cancer, particularly those with very high level of ER expression, PIP appears to play an important role in proliferation and invasion as well as acquired resistance to tamoxifen. [24]
The prolactin receptor (PRLR) is a type I cytokine receptor encoded in humans by the PRLR gene on chromosome 5p13-14. It is the receptor for prolactin (PRL). The PRLR can also bind to and be activated by growth hormone (GH) and human placental lactogen (hPL). The PRLR is expressed in the mammary glands, pituitary gland, and other tissues. It plays an important role in lobuloalveolar development of the mammary glands during pregnancy and in lactation.
Midkine, also known as neurite growth-promoting factor 2 (NEGF2), is a protein that in humans is encoded by the MDK gene.
Heparin-binding EGF-like growth factor (HB-EGF) is a member of the EGF family of proteins that in humans is encoded by the HBEGF gene.
HLA class II histocompatibility antigen, DM beta chain is a protein that in humans is encoded by the HLA-DMB gene.
Protein kinase C eta type is an enzyme that in humans is encoded by the PRKCH gene.
Signal regulatory protein α (SIRPα) is a regulatory membrane glycoprotein from SIRP family expressed mainly by myeloid cells and also by stem cells or neurons.
HLA class II histocompatibility antigen, DM alpha chain is a protein that in humans is encoded by the HLA-DMA gene.
Zinc-alpha-2-glycoprotein is a protein that in humans is encoded by the AZGP1 gene.
Beta-microseminoprotein is a protein that in humans is encoded by the MSMB gene. For historical reasons, the scientific literature may also refer to this protein as Prostate secretory protein 94 (PSP94), microseminoprotein (MSP), microseminoprotein-beta (MSMB), beta-inhibitin, prostatic inhibin peptide (PIP), and inhibitin like material (ILM).
Galectin-3-binding protein is a protein that in humans is encoded by the LGALS3BP gene.
CD166 antigen is a 100-105 kD typeI transmembrane glycoprotein that is a member of the immunoglobulin superfamily of proteins. In humans it is encoded by the ALCAM gene. It is also called CD166, MEMD, SC-1/DM-GRASP/BEN in the chicken, and KG-CAM in the rat.
Milk fat globule-EGF factor 8 protein (Mfge8), also known as lactadherin, is a protein that in humans is encoded by the MFGE8 gene.
HLA class II histocompatibility antigen, DO beta chain is a protein that in humans is encoded by the HLA-DOB gene.
Cystatin-M is a protein that in humans is encoded by the CST6 gene.
Chloride channel accessory 2 is a protein that in humans is encoded by the CLCA2 gene.
Mucin-like protein 1 is a protein that in humans is encoded by the MUCL1 gene.
HLA class II histocompatibility antigen, DX beta chain is a protein that in humans is encoded by the HLA-DQB2 gene.
Galectin-4 is a protein that in humans is encoded by the LGALS4 gene.
Forkhead box protein A1 (FOXA1), also known as hepatocyte nuclear factor 3-alpha (HNF-3A), is a protein that in humans is encoded by the FOXA1 gene.
Pure apocrine carcinoma of the breast (PACB) is a rare carcinoma derived from the epithelial cells in the lactiferous ducts of the mammary gland. The mammary gland is an apocrine gland. Its lactiferous ducts have two layers of epithelial cells, a luminal layer which faces the duct's lumen and a basal layer which lies beneath the luminal layer. There are at least 4 subtypes of epithelial cells in these ducts: luminal progenitor cells and luminal mature cells which reside in the luminal layer and mammary stem cells and basal cells which reside in the basal layer. Examination of the genes expressed in PACB cancer cells indicate that most of these tumors consist of cells derived from luminal cells but a minority of these tumors consist of cells derived from basal cells.