Octamer transcription factor-3/4 (OCT3/4)

Characteristics

OCT3/4 (OCT4, FOU5F1) is a nuclear POU-domain octamer binding transcription factor specifically expressed in cells with pluripotent capacity, i.e., embryonic stem cells and germinal cells. The gene is located on chromosome 6p21.3.  
 

Neoplasms

In virtually all cases of seminoma/dysgerminoma/germinoma, embryonal carcinoma, and the germ
cell component of gonadoblastoma, OCT3/4 is expressed strongly in more than 90% of

the nuclei, sometimes with a dot-like cytoplasmic reaction as well. Also the germinal tumour precursor lesion, intratubular germ cell neoplasia unclassified (IGCNU), is strongly stained. OCT3/4 is not found in other germ cell tumours (spermatocytic seminoma, choriocarcinoma or yolk sac tumour). Other tumour types are virtually always negative (very rarely, staining – mostly focal and weak – has been seen in carcinomas of the bladder, kidney and lung, and in Ewing sarcoma).

Application

Classification of germ cell tumours, viz. identification of seminoma/dysgerminoma/germinoma, embryonal carcinoma, and gonadoblastoma, as well as IGCNU. OCT3/4 gives a better signal/noise ratio than placental alkaline phosphatase (PLAP) in seminoma and related tumours, and is more sensitive than CD30 in embryonal carcinoma, particularly after chemotherapy (where CD30 is frequently lost).
 

Visualization

mAb clone C10 and pAb goat anti-OCT4 antibody (C20 Santa Cruz) has been found to work well. Heat induced epitope retrieval is mandatory (Citrate buffer pH6 or Tris/EDTA buffer pH9). Clone 9E3 cannot be recommended. 
Control tissue: As OCT3/4 is not detected in any normal adult tissue, a seminoma or embryonal carcinoma must be used. The staining should be as strongly as possible in the nuclei expected to stain.

Assessments

Run 24 2008