Aldo-keto reductase family 1 member C3 (AKR1C3), also known as 17ò-hydroxysteroid dehydrogenase type 5 (17ò-HSD5, HSD17B5) or 3ñ-hydroxysteroid dehydrogenase type 2 (3ñ-HSD2) is a steroidogenic enzyme that in humans is encoded by the AKR1C3 gene.
This gene encodes a member of the aldo/keto reductase superfamily, which consists of more than 40 known enzymes and proteins. These enzymes catalyze the conversion of aldehydes and ketones to their corresponding alcohols by utilizing NADH and/or NADPH as cofactors. The enzymes display overlapping but distinct substrate specificity. This enzyme catalyzes the reduction of prostaglandin D<sub>2</sub>, prostaglandin H<sub>2</sub>, and phenanthrenequinone, and the oxidation of prostaglandin F<sub>2ñ</sub> to prostaglandin D<sub>2</sub>. It is also capable of metabolizing estrogen and progesterone.
AKR1C3 may play an important role in the development of allergic diseases such as asthma, and may also have a role in controlling cell growth and/or differentiation. This gene shares high sequence identity with three other gene members and is clustered with those three genes at chromosome 10p15-p14.
AKR1C3 is overexpressed in prostate cancer (PCa) and is associated with the development of castration-resistant prostate cancer (CRPC). In addition, AKR1C3 overexpression may serve as a promising biomarker for prostate cancer progression.