SOX2 (HMV338)

SOX2, also known as SRY (sex determining region Y)-box 2, is a member of the SOX family of transcription factors coded by the SOX2 gene located on chromosome 3q26.3-27. SOX2 is essential for maintaining the cell’s capability for self-renewal and therefore has a critical role in maintenance of embryonic and neural stem cells. Forced re-expression of SOX2 together with Oct4, c-Myc, and Klf4 is sufficient to reprogram differentiated cells into pluripotent stem cells. SOX2 is also critical for normal embryonal development. It is expressed already at a two cell stage of murine embryo formation. SOX2-deficient embryos die straight after implantation. Inactivating mutations of SOX2 occur in patients with bilateral anophthalmia, a severe structural eye deformity.  Dysregulation of SOX2 also plays a role in the pathogenesis of cancer. SOX2 expression has been linked to cancer stem cell formation, epithelial-mesenchymal transition, migration, invasion, increased cell proliferation, resistance to apoptosis and therapy, colony formation, and metastasis in various cancer types.

Images describing the SOX2 staining pattern in normal tissues obtained by the antibody HMV338 are shown in our “Normal Tissue Gallery”.

These findings are largely consistent with the RNA data described in the Human Protein Atlas (Tissue expression SOX2). SOX2 staining by HMV338 is most prominent in tissues covered by non-keratinizing squamous epithelium, pituitary gland, brain, stomach, but also occurs in selected cell types of other organs.

Positive control = Tonsil: A moderate to strong SOX2 staining should be seen in the bottom 2/3 of squamous epithelial cells.

Negative control = Tonsil: SOX2 staining should be absent in lymphocytes and in other immune cells.

Normal tissue gallery

Cancer tissue gallery

No data available at the moment

IHC users have different preferences on how the stains should look like. Some prefer high staining intensity of the target stain and even accept some background. Others favor absolute specificity and lighter target stains. Factors that invariably lead to more intense staining include higher concentration of the antibody and visualization tools, longer incubation time, higher temperature during incubation, higher temperature and longer duration of the heat induced epitope retrieval (slide pretreatment). The impact of the pH during slide pretreatment has variable effects and depends on the antibody and the target protein.

All images and data shown here and in our image galleries are obtained by the manual protocol described below. Other protocols resulting in equivalent staining are described as well.

Manual protocol

Freshly cut sections should be used (less than 10 days between cutting and staining). Heat-induced antigen retrieval for 5 minutes in an autoclave at 121°C in pH 7,8 Target Retrieval Solution buffer. Apply HMV338 at a dilution of 1:150 at 37°C for 60 minutes. Visualization of bound antibody by the EnVision Kit (Dako, Agilent) according to the manufacturer’s directions.

• The diagnostic, prognostic, and predictive relevance of SOX2 expression in tumors and in preneoplastic disease needs to be further investigated.
• SOX2 may play a functional role in cancer drug resistance.
• SOX2 represents a promising therapeutic target.
• SOX2 is a critical gene in stem cell research.

There are two ways how the specificity of antibodies can be documented for immunohistochemistry on formalin fixed tissues. These are: 1. Comparison with a second independent method for target expression measurement across a large number of different tissue types (orthogonal strategy), and 2. Comparison with one or several independent antibodies for the same target and showing that all positive staining results are also seen with other antibodies for the same target (independent antibody strategy). 

Orthogonal validation: For the antibody HMV338 specificity is suggested by the good concordance of the immunostaining data with data from three independent RNA screening studies, including the Human Protein Atlas (HPA) RNA-seq tissue dataset, the FANTOM5 project, and the Genotype-Tissue Expression (GTEx) project, which are all summarized in the Human Protein Atlas (Tissue expression SOX2). 

SOX2 positivity by HMV338 is detectable in all tissues with documented SOX2 RNA expression (brain, hypophysis, salivary gland, esophagus, stomach, colon, testis, prostate, cervix uteri, fallopian tube, tonsil). Tissues without previously documented SOX2 RNA expression but SOX2 positivity by HMV338 had either very few positive cells that were probably not detected in RNA studies (corpuscles of Hassall’s in the thymus) or were previously not analyzed on the RNA level (respiratory epithelium, bronchial glands, paranasal sinus).

Comparison of antibodies: True expression of SOX2 in all cell types found SOX2 positive by HMV338 (including corpuscles of Hassall’s in the thymus, respiratory epithelium in the bronchus and the paranasal sinus, bronchial glands) is corroborated by the staining of all these cell types by another commercially available independent antibody (termed “validation antibody”). Independence of the validation antibody is demonstrated by substantial cytoplasmic staining in various tissues by the validation antibody.

Normal tissue gallery