Bexarotene
Encyclopedia
Bexarotene is an oral antineoplastic agent indicated by the FDA (in 2000) for cutaneous T cell lymphoma
. It has been used off-label for lung cancer
, breast cancer
, and Kaposi's sarcoma
.
specifically selective for retinoid X receptor
s, as opposed to the retinoic acid receptor
s.
RXRs are located primarily in visceral organs such as the liver and kidney. Activated RXRs form homodimers or heterodimers with retinoic acid receptor
s, vitamin D
receptors, thyroid
receptors or peroxisome proliferator-activated receptor
s. Once activated, these retinoid receptor dimers bind to DNA at retinoic acid response elements and act as transcription factors that regulate the expression of genes which control cellular differentiation and proliferation. Retinoid agonists can activate the expression of retinoid regulated genes by removing negative transcription control or by facilitating positive transcriptional activity. They exert anticancer action by interfering with the growth of cells of the tumor.
Cutaneous T Cell lymphoma
Cutaneous T cell lymphoma is a class of non-Hodgkin's lymphoma, which is a type of cancer of the immune system. Unlike most non-Hodgkin's lymphomas , CTCL is caused by a mutation of T cells. The malignant T cells in the body initially migrate to the skin, causing various lesions to appear...
. It has been used off-label for lung cancer
Lung cancer
Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary...
, 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...
, and Kaposi's sarcoma
Kaposi's sarcoma
Kaposi's sarcoma is a tumor caused by Human herpesvirus 8 , also known as Kaposi's sarcoma-associated herpesvirus . It was originally described by Moritz Kaposi , a Hungarian dermatologist practicing at the University of Vienna in 1872. It became more widely known as one of the AIDS defining...
.
Mechanism
Bexarotene is a retinoidRetinoid
The retinoids are a class of chemical compounds that are related chemically to vitamin A. Retinoids are used in medicine, primarily due to the way they regulate epithelial cell growth....
specifically selective for retinoid X receptor
Retinoid X receptor
The retinoid X receptor is a type of nuclear receptor that is activated by 9-cis retinoic acid. There are three retinoic X receptors : RXR-alpha, RXR-beta, and RXR-gamma, encoded by the , , genes, respectively....
s, as opposed to the retinoic acid receptor
Retinoic acid receptor
The retinoic acid receptor is a type of nuclear receptor that is activated by both all-trans retinoic acid and 9-cis retinoic acid. There are three retinoic acid receptors , RAR-alpha, RAR-beta, and RAR-gamma, encoded by the , , genes, respectively...
s.
RXRs are located primarily in visceral organs such as the liver and kidney. Activated RXRs form homodimers or heterodimers with retinoic acid receptor
Retinoic acid receptor
The retinoic acid receptor is a type of nuclear receptor that is activated by both all-trans retinoic acid and 9-cis retinoic acid. There are three retinoic acid receptors , RAR-alpha, RAR-beta, and RAR-gamma, encoded by the , , genes, respectively...
s, vitamin D
Vitamin D
Vitamin D is a group of fat-soluble secosteroids. In humans, vitamin D is unique both because it functions as a prohormone and because the body can synthesize it when sun exposure is adequate ....
receptors, thyroid
Thyroid
The thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
receptors or peroxisome proliferator-activated receptor
Peroxisome proliferator-activated receptor
In the field of molecular biology, the peroxisome proliferator-activated receptors are a group of nuclear receptor proteins that function as transcription factors regulating the expression of genes...
s. Once activated, these retinoid receptor dimers bind to DNA at retinoic acid response elements and act as transcription factors that regulate the expression of genes which control cellular differentiation and proliferation. Retinoid agonists can activate the expression of retinoid regulated genes by removing negative transcription control or by facilitating positive transcriptional activity. They exert anticancer action by interfering with the growth of cells of the tumor.