Category: IHC-Antibodies

Olig2 is a transcription factor involved in oligodendroglial specification. It is expressed in most glial tumors, such as oligodendrogliomas and astrocytomas, but has been not found in the non-glial tumors including neuroepithelial tumors, ependymomas, sub ependymomas, medulloblastomas, and nonneuroepithelial tumors, such as CNS lymphomas, meningiomas, schwannomas, atypical teratoid/rhabdoid tumor, and hemangioblastomas. Although more than half of glioblastomas are positive for Olig2, expression is very weak in terms of both percentage of labeled cells and intensity. Compared to the strong staining seen in glioma samples, a weak expression is observed in non-tumoral brain tissue.

Napsin A is a pepsin-like aspartate protease with a molecular weight of about 38 kDa. Napsin A is closely related to Napsin B. Napsin is expressed as a single-chain protein in type II pneumocytes and in adenocarcinomas of the lung and kidney. The high specificity of Napsin A in lung adenocarcinomas is useful in distinguishing such primary adenocarcinomas from adenocarcinomas of unknown origin.

p40, also known as deltaNp63, is an isoform of TP63 that lacks the transactivation domain. p40 is expressed in the nucleus of the normal breast myoepithelium and in the epidermal cells of the skin. In tumor tissues p40 staining is observed in lung and cervical squamous cell carcinoma. p40 antibody recognizes the shortest variant of human p53 and can be a valuable marker in cases where p63 has been used traditionally. The transcription factor p63 was identified as a p53 homolog. p63 is currently the most commonly used marker for squamous cell carcinoma of the lung (SqCC). In a recent study, the p40 staining was equivalent to the sensitivity to SqCC of p63 but was significantly better specific than p63. This report strongly supports the routine use of p40 as an alternative to p63 in the diagnosis of pulmonary squamous cell carcinoma. p40 can prove to be an important antibody in the differential diagnosis of lung adenocarcinoma against lung SqCC.

Progesterone receptor (PR) is a nuclear hormone receptor that activates transcription of various genes, especially in reproductive tissues, regulated by its ligand progesterone. PR is predominantly expressed in female sex steroid responsive tissues such as the mammary gland, uterus and ovary. Two isoforms exist: PR-A (94 kDa) and PR-B (114 kDa). Ratio of these isoforms varies in reproductive tissues and during carcinogenesis. PR is expressed in about 65-75% of breast carcinomas. The expression of PR is usually closely linked to the expression of the estrogen receptor (ER), as both receptors are hormonally regulated. PR-positive status is often used as an indicator for a better prognosis and a better response to hormone therapies.

 DNA mismatch repair (MMR) system consists of four major proteins called MLH1, MSH2, MSH6, and PMS2. These proteins work two by two, MLH1 with PMS2 and MSH2 with MSH6. Loss of function of one of the four proteins leads to inactivation of the MMR system, resulting in a loss of fidelity of the replication and an accumulation of mutations thereby leading to microsatellite instability (MSI). MSI is associated with hereditary nonpolyposis colorectal cancer (HNPCC, Lynch syndrome), which is characterized by the development of colorectal cancer, endometrial cancer and various other tumors at early age.
Loss of PMS2 function due to gene mutation or epigenetic changes is characterized by absence of nuclear expression in neoplastic cells, whereas intact nuclear PMS2 expression indicates normal PMS2 function and no gene mutations. PMS2 is normally expressed in most cases of sporadic colorectal cancer (CRC). Isolated loss of PMS2 staining is an uncommon immunophenotype among CRCs, accounting for approximately 4%. Anti-PMS2 is useful in detection of MSI, especially in a panel with MSH2 (QR010), MSH6 (QR011) and MLH1 (QM003).

p16, also designated p16(INK4a), cyclin-dependent kinase inhibitor 2A or CDKN2A, is a tumor suppressor protein that slows cell division by slowing the progression of the cell cycle from the G1 phase to the S phase. Mutations in the p16 gene – associated with loss or overexpression of the protein – are associated with increased risk of a wide range of cancers and cancer precursor lesions. When overexpressed, the protein is detected both in the nucleus and cytoplasm. p16 is expressed in almost 100% of cervical carcinomas, especially in squamous cell carcinomas of the cervix. The vast majority of these carcinomas are associated with human papilloma virus (HPV) infection, especially high-risk HPV types such as HPV 16 and 18. The overexpression of p16 is caused by the inactivation of the retinoblastoma protein (Rb) by the viral E7 oncogene, which leads to the upregulation of p16. Strong and full thickness staining of p16 in the cervix epithelium is highly supportive of high grade squamous epithelial lesion (HSIL), while weak and intermediate staining favors low grade squamous epithelial lesion (LSIL).

PSA is a glycoprotein enzyme that is secreted by the epithelial cells of the prostate gland. PSA is produced for the ejaculate, where it liquefies semen in the seminal coagulum and allows sperm to swim freely. It is also believed to be instrumental in dissolving cervical mucus, allowing the entry of sperm into the uterus. PSA is present in small quantities in the serum of men with healthy prostates but is often elevated in the presence of prostate cancer or other prostate disorders. It is not uniquely an indicator of prostate cancer but may also detect prostatitis or benign prostatic hyperplasia.

PTEN is a phosphoinositide3-phosphatase and is identified as a tumor suppressor that is mutated in a large number of cancers at high frequency. PTEN contains a tensin-like domain as well as a catalytic domain similar to that of the dual specificity protein tyrosine phosphatases. Expression is found at a relatively high levels in all adult tissues including heart, brain, placenta, lung, liver, muscle, kidney, and pancreas.

PAX5 is a transcription factor and important regulator in early development. Alterations in the expression of PAX5 gene are thought to contribute to neoplastic transformation. The PAX5 gene encodes the B-cell lineage specific activator protein (BSAP) that is expressed at early, but not late stages of B-cell differentiation. Its expression has also been detected in developing CNS and testis, therefore, PAX5 gene product may not only play an important role in B-cell differentiation, but also in neural development and spermatogenesis.

PAX2 is a transcription factor that is strongly expressed during kidney development, in the metanephric mesenchyma after ureter bud induction and is a key factor for the mesenchyma-epithelium conversion, in renal carcinoma cell lines and, in papillary renal cell carcinoma, and chromophobe renal cell carcinomas.

Podoplanin is a type-I integral membrane glycoprotein that is selectively expressed in lymphatic endothelium. The exact molecular function of podoplanin in the lymphatic endothelium has remained unclear. This antibody detects lymphangiomas, Kaposi sarcomas and a subset of angiosarcomas with probable lymphatic differentiation.

p21/WAF1 is a potent cyclin-dependent kinase inhibitor that binds and inhibits the activity of cyclin-CDK2 or -CDK1 complexes, and thus functions as a regulator of cell cycle progression at G1. It is expressed in all adult human tissues, with lower levels in the brain.