Metadherin, also known as protein LYRIC or astrocyte elevated gene-1 protein (AEG-1) is a protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that in humans is encoded by the MTDH gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

.

AEG-1 acts as a oncogene

Oncogene

An oncogene is a gene that has the potential to cause cancer. In tumor cells, they are often mutated or expressed at high levels.An oncogene is a gene found in the chromosomes of tumor cells whose activation is associated with the initial and continuing conversion of normal cells into cancer...

 in melanoma, malignant glioma, breast cancer and hepatocellular carcinoma. It is highly expressed in these cancers and helps in progression and development of these cancers. It is induced by c-Myc

Myc

Myc is a regulator gene that codes for a transcription factor. In the human genome, Myc is located on chromosome 8 and is believed to regulate expression of 15% of all genes through binding on Enhancer Box sequences and recruiting histone acetyltransferases...

 oncogene and plays very important role in anchorage independent growth of cancer cells. It is also involved in HIF-1alpha

HIF1A

Hypoxia-inducible factor 1, alpha subunit , also known as HIF1A, is a protein that in humans is encoded by the HIF1A gene...

 mediated Angiogenesis. AEG-1 also interacts with SND1

SND1

Staphylococcal nuclease domain-containing protein 1 also known as 100 kDa coactivator or Tudor domain-containing protein 11 is a protein that in humans is encoded by the SND1 gene...

 and involved in RNA-induced silencing complex

RNA-induced silencing complex

RNA-Induced Silencing Complex, or RISC, is a multiprotein complex that incorporates one strand of a small interfering RNA or micro RNA . RISC uses the siRNA or miRNA as a template for recognizing complementary mRNA. When it finds a complementary strand, it activates RNase and cleaves the RNA...

 (RISC) and plays very important role in RISC and miRNA functions.

Clinical significance

Elevated expression of the metastasis gene metadherin (MTDH), which is overexpressed in more than 40% of breast cancer

Breast cancer

Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...

s, is associated with poor clinical outcomes. MTDH has a dual role in promoting metastatic

Metastasis

Metastasis, or metastatic disease , is the spread of a disease from one organ or part to another non-adjacent organ or part. It was previously thought that only malignant tumor cells and infections have the capacity to metastasize; however, this is being reconsidered due to new research...

 seeding and enhancing chemoresistance. MTDH is therefore a potential therapeutic target for enhancing chemotherapy

Chemotherapy

Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....

and reducing metastasis.