View source for CYP17A1

{{Infobox gene}}

'''Cytochrome P450 17A1''', also called '''steroid 17α-monooxygenase''', '''17α-hydroxylase''', '''17,20-lyase''', or '''17,20-desmolase''', is an [[enzyme]] of the [[hydroxylation|hydroxylase]] type that in humans is encoded by the ''CYP17A1'' [[gene]] on [[Chromosome 10 (human)|chromosome 10]].<ref name=":0" /> It is ubiquitously expressed in many tissues and cell types, including the [[zona reticularis]] of the [[adrenal cortex]] and [[zona fasciculata]] as well as [[gonad]]al tissues.<ref>{{Cite web|url=http://biogps.org/#goto=genereport&id=1586|title=BioGPS - your Gene Portal System|website=biogps.org|access-date=2016-10-11}}</ref><ref name="isbn1-4160-2328-3" /> This gene encodes a member of the [[cytochrome P450]] superfamily of enzymes. The cytochrome P450 proteins are generally regarded as [[monooxygenase]]s that catalyze many reactions involved in drug metabolism and synthesis of [[cholesterol]], [[steroid]]s, and other [[lipid]]s, including the remarkable carbon-carbon bond scission catalyzed by this enzyme. This protein localizes to the [[endoplasmic reticulum]]. It has both 17α-hydroxylase and 17,20-lyase activities, and is a key enzyme in the steroidogenic pathway that produces [[progestin]]s, [[mineralocorticoid]]s, [[glucocorticoid]]s, [[androgen]]s, and [[estrogen]]s. More specifically, CYP17A1 acts upon [[pregnenolone]] and [[progesterone]] to add a [[hydroxyl]] (-OH) group at carbon 17 of the steroid D ring (the hydroxylase activity), or acts upon [[17α-hydroxyprogesterone]] and [[17α-hydroxypregnenolone]] to split the side-chain off the steroid nucleus (the [[lyase]] activity).<ref name="isbn1-4160-2328-3">{{cite book | author = Boulpaep EL | author2 = Boron, WF | title = Medical physiology: a cellular and molecular approach | publisher = Elsevier Saunders | location = St. Louis, Mo | year = 2005 | page = 1180 | isbn = 1-4160-2328-3 }}</ref> The ''CYP17A1'' gene also contains one of 27 [[SNPs]] associated with increased risk of [[coronary artery disease]].<ref name="ReferenceA">{{cite journal | vauthors = Mega JL, Stitziel NO, Smith JG, Chasman DI, Caulfield MJ, Devlin JJ, Nordio F, Hyde CL, Cannon CP, Sacks FM, Poulter NR, Sever PS, Ridker PM, Braunwald E, Melander O, Kathiresan S, Sabatine MS | title = Genetic risk, coronary heart disease events, and the clinical benefit of statin therapy: an analysis of primary and secondary prevention trials | journal = Lancet | volume = 385 | issue = 9984 | pages = 2264–71 | date = June 2015 | pmid = 25748612 | doi = 10.1016/S0140-6736(14)61730-X | pmc=4608367}}</ref>

==Structure==

===Gene===
The ''CYP17A1'' gene resides on chromosome 10 at the band 10q24.3 and contains 8 [[exon]]s.<ref name=":0" /> The [[cDNA]] of this gene spans a length of 1527 [[Base pair|bp]].<ref name=":1">{{cite journal | vauthors = Vasaitis TS, Bruno RD, Njar VC | title = CYP17 inhibitors for prostate cancer therapy | journal = The Journal of Steroid Biochemistry and Molecular Biology | volume = 125 | issue = 1-2 | pages = 23–31 | date = May 2011 | pmid = 21092758 | doi = 10.1016/j.jsbmb.2010.11.005 | pmc=3047603}}</ref>

===Protein===
CYP17A1 is a 57.4 [[kDa]] protein that belongs to the cytochrome P450 family.<ref>{{Cite web|url=https://www.uniprot.org/uniprot/P05093|title=CYP17A1 - Steroid 17-alpha-hydroxylase/17,20 lyase - Homo sapiens (Human) - CYP17A1 gene & protein|website=www.uniprot.org|access-date=2016-10-11}}</ref><ref>{{cite journal | vauthors = Estrada DF, Laurence JS, Scott EE | title = Cytochrome P450 17A1 Interactions with the FMN Domain of Its Reductase as Characterized by NMR | journal = The Journal of Biological Chemistry | volume = 291 | issue = 8 | pages = 3990–4003 | date = February 2016 | pmid = 26719338 | doi = 10.1074/jbc.M115.677294 | pmc = 4759177 }}</ref> The protein encoded by its cDNA is composed of 508 [[amino acid residues]]. As an enzyme, CYP17A1 possesses an [[active site]] that associates with a [[heme]] prosthetic group to catalyze biosynthetic reactions.<ref name=":1" /> Based on its known structures while bound to two steroidal inhibitors, abiraterone and [[galeterone]], CYP17A1 possesses the canonical cytochrome P450 fold present in other complex P450 enzymes that participate in [[steroidogenesis]] or [[cholesterol]] metabolism, though it orients the steroid ligands toward the F and G helices, perpendicular to the heme group, rather than the β1 sheet.<ref>{{cite journal | vauthors = DeVore NM, Scott EE | title = Structures of cytochrome P450 17A1 with prostate cancer drugs abiraterone and TOK-001 | journal = Nature | volume = 482 | issue = 7383 | pages = 116–9 | date = February 2012 | pmid = 22266943 | doi = 10.1038/nature10743 | pmc=3271139}}</ref><ref>{{cite journal | vauthors = Petrunak EM, DeVore NM, Porubsky PR, Scott EE | title = Structures of human steroidogenic cytochrome P450 17A1 with substrates | journal = The Journal of Biological Chemistry | volume = 289 | issue = 47 | pages = 32952–64 | date = November 2014 | pmid = 25301938 | doi = 10.1074/jbc.M114.610998 | pmc=4239641}}</ref>

==Expression==
[[Gene expression|Expression]] of CYP17A1 has been found in all of the traditional [[steroidogenic]] [[tissue (biology)|tissue]]s except the [[placenta]], including the [[zona reticularis]] and [[zona fasciculata]] of the [[adrenal cortex]], the [[Leydig cell]]s of the [[testicle|testes]], the [[thecal cell]]s of the [[ovary|ovaries]], and, more recently, in [[luteinization|luteinized]] [[granulosa cell]]s in [[ovarian follicle]]s.<ref name="pmid21095220">{{cite journal | vauthors = Storbeck KH, Swart P, Africander D, Conradie R, Louw R, Swart AC | title = 16α-hydroxyprogesterone: origin, biosynthesis and receptor interaction | journal = Mol. Cell. Endocrinol. | volume = 336 | issue = 1-2 | pages = 92–101 | year = 2011 | pmid = 21095220 | doi = 10.1016/j.mce.2010.11.016 | url = }}</ref> In addition to classical steroidogenic tissue, CYP17A1 has also been detected in the [[heart]], [[kidney]], and [[adipose tissue]].<ref name="pmid21095220" /> In the [[fetus]], CYP17A1 has been reported in the kidney, [[thymus]], and [[spleen]].<ref name="pmid21095220" />

==Function==
CYP17A1 is a member of the [[cytochrome P450]] superfamily of enzymes localized in the endoplasmic reticulum. Proteins in this family are monooxygenases that catalyze synthesis of [[cholesterol]], [[steroid]]s and other lipids and are involved in drug metabolism.<ref name=":0">{{Cite web|url=https://www.ncbi.nlm.nih.gov/gene/1586|title=CYP17A1 cytochrome P450 family 17 subfamily A member 1 [Homo sapiens (human)] - Gene - NCBI|website=www.ncbi.nlm.nih.gov|access-date=2016-09-27}}</ref> CYP17A1 has both 17α-hydroxylase activity and 17,20-lyase activity. The 17α-hydroxylase activity of CYP17A1 is required for the generation of [[glucocorticoid]]s such as cortisol, but both the hydroxylase and 17,20-lyase activities of CYP17A1 are required for the production of [[androgen]]ic and [[Oestrogenine|oestrogenic]] sex steroids by converting [[17α-hydroxypregnenolone]] to [[Dehydroepiandrosterone|dehydroepiandrosterone (DHEA)]].<ref>{{cite journal | vauthors = DeVore NM, Scott EE | title = Structures of cytochrome P450 17A1 with prostate cancer drugs abiraterone and TOK-001 | journal = Nature | volume = 482 | issue = 7383 | pages = 116–9 | date = February 2012 | pmid = 22266943 | pmc = 3271139 | doi = 10.1038/nature10743 }}</ref> Mutations in this gene are associated with isolated steroid-17α-hydroxylase deficiency, 17α-hydroxylase/17,20-lyase deficiency, [[pseudohermaphroditism]], and [[Congenital adrenal hyperplasia|adrenal hyperplasia]].<ref name=":0"/>

Furthermore, the 17,20-lyase activity is dependent on cytochrome [[Cytochrome P450 reductase|P450 oxidoreductase]] (POR) cytochrome b5 (CYB5) and [[phosphorylation]].<ref>{{cite journal | vauthors = Udhane SS, Dick B, Hu Q, Hartmann RW, Pandey AV | title = Specificity of anti-prostate cancer CYP17A1 inhibitors on androgen biosynthesis | journal = Biochemical and Biophysical Research Communications | volume = 477 | issue = 4 | pages = 1005–10 | date = September 2016 | pmid = 27395338 | doi = 10.1016/j.bbrc.2016.07.019 }}</ref><ref>{{cite journal | vauthors = Pandey AV, Miller WL | title = Regulation of 17,20 lyase activity by cytochrome b5 and by serine phosphorylation of P450c17 | journal = The Journal of Biological Chemistry | volume = 280 | issue = 14 | pages = 13265–71 | date = April 2005 | pmid = 15687493 | doi = 10.1074/jbc.M414673200 }}</ref><ref name="ReferenceB">{{cite journal | vauthors = Zhang LH, Rodriguez H, Ohno S, Miller WL | title = Serine phosphorylation of human P450c17 increases 17,20-lyase activity: implications for adrenarche and the polycystic ovary syndrome | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 92 | issue = 23 | pages = 10619–23 | date = November 1995 | pmc = 40663 | pmid = 7479852 | doi=10.1073/pnas.92.23.10619}}</ref> Cytochrome b5 acts as a facilitator for 17,20 lyase activity of CYP17A1 and can donate a second electron to some P450s. In humans the production of [[testosterone]] via pregnenolone to17-OHPreg and DHEA by the CYP17A1 requires POR.<ref>{{cite journal | vauthors = Fukami M, Homma K, Hasegawa T, Ogata T | title = Backdoor pathway for dihydrotestosterone biosynthesis: implications for normal and abnormal human sex development | journal = Developmental Dynamics | volume = 242 | issue = 4 | pages = 320–9 | date = April 2013 | pmid = 23073980 | doi = 10.1002/dvdy.23892 }}</ref> Human P450c17 is phosphorylated on serine and threonine residues by a [[CAMP-dependent protein kinase A|cAMP-dependent protein kinase]]. Phosphorylation of P450c17 increases 17,20-lyase activity, while dephosphorylation virtually eliminates this activity.<ref name="ReferenceB"/>

==Clinical significance==
Mutations in this gene are associated with rare forms of [[congenital adrenal hyperplasia]], specifically [[Congenital adrenal hyperplasia due to 17α-hydroxylase deficiency|17α-hydroxylase deficiency/17,20-lyase deficiency]] and [[isolated 17,20-lyase deficiency]].<ref>{{cite web | title = Entrez Gene: CYP17A1 cytochrome P450, family 17, subfamily A, polypeptide 1| url = https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=1586| accessdate = }}</ref>

In humans, the CYP17A1 gene is largely associated with endocrine effects and steroid hormone metabolism.<ref>{{cite journal | vauthors = Ma YN, Cao CY, Wang QW, Gui WJ, Zhu GN | title = Effects of azocyclotin on gene transcription and steroid metabolome of hypothalamic-pituitary-gonad axis, and their consequences on reproduction in zebrafish (Danio rerio) | journal = Aquatic Toxicology | volume = 179 | pages = 55–64 | date = October 2016 | pmid = 27571716 | doi = 10.1016/j.aquatox.2016.08.006 }}</ref><ref>{{cite journal | vauthors = Legendre A, Elie C, Ramambason C, Manens L, Souidi M, Froment P, Tack K | title = Endocrine effects of lifelong exposure to low-dose depleted uranium on testicular functions in adult rat | journal = Toxicology | volume = 368-369 | pages = 58–68 | date = August 2016 | pmid = 27544493 | doi = 10.1016/j.tox.2016.08.014 }}</ref><ref>{{cite journal | vauthors = Yadav R, Petrunak EM, Estrada DF, Scott EE | title = Structural insights into the function of steroidogenic cytochrome P450 17A1 | journal = Molecular and Cellular Endocrinology | date = August 2016 | pmid = 27566228 | doi = 10.1016/j.mce.2016.08.035 }}</ref> Furthermore, mutations in the CYP17A1 gene are associated with rare forms of congenital adrenal hyperplasia, in particular 17α-hydroxylase deficiency/17,20-lyase deficiency and isolated 17,20-lyase deficiency. Overall, CYP17A1 is an important target for inhibition in the treatment of prostate cancer because it produces androgen that is required for tumor cell growth. <ref>{{cite journal | vauthors = Kostin VA, Zolottsev VA, Kuzikov AV, Masamrekh RA, Shumyantseva VV, Veselovsky AV, Stulov SV, Novikov RA, Timofeev VP, Misharin AY | title = Oxazolinyl derivatives of [17(20)E]-21-norpregnene differing in the structure of A and B rings. Facile synthesis and inhibition of CYP17A1 catalytic activity | journal = Steroids | volume = 115 | pages = 114–122 | date = November 2016 | pmid = 27505042 | doi = 10.1016/j.steroids.2016.06.002 }}</ref> <ref name = "Bonomo_2016">{{cite journal | vauthors = Bonomo S, Hansen CH, Petrunak EM, Scott EE, Styrishave B, Jørgensen FS, Olsen L | title = Promising Tools in Prostate Cancer Research: Selective Non-Steroidal Cytochrome P450 17A1 Inhibitors | journal = Scientific Reports | volume = 6 | pages = 29468 | date = 2016-01-01 | pmid = 27406023 | doi = 10.1038/srep29468 | pmc=4942611}}</ref> Currently, the FDA has approved only one CYP17A1 inhibitor, abiraterone, which contains a steroidal scaffold that is similar to the endogenous CYP17A1 substrates. Abiraterone is structurally similar to the substrates of other cytochrome P450 enzymes involved in steroidogenesis, and interference can pose a liability in terms of side effects. Using [[nonsteroidal]] scaffolds is expected to enable the design of compounds that interact more selectively with CYP17A1.<ref name = "Bonomo_2016"/> Potent inhibitors of the CYP17A1 enzyme provide a last line defense against ectopic androgenesis in advanced prostate cancer.<ref>{{cite journal | vauthors = Bordeau BM, Ciulla DA, Callahan BP | title = Hedgehog Proteins Consume Steroidal CYP17A1 Antagonists: Potential Therapeutic Significance in Advanced Prostate Cancer | journal = ChemMedChem | volume = 11 | issue = 18 | pages = 1983–6 | date = September 2016 | pmid = 27435344 | doi = 10.1002/cmdc.201600238 }}</ref>

===Clinical marker===
A multi-locus genetic risk score study based on a combination of 27 loci, including the CYP17A1 gene, identified individuals at increased risk for both incident and recurrent coronary artery disease events, as well as an enhanced clinical benefit from statin therapy. The study was based on a community cohort study (the Malmo Diet and Cancer study) and four additional randomized controlled trials of primary prevention cohorts (JUPITER and ASCOT) and secondary prevention cohorts (CARE and PROVE IT-TIMI 22).<ref name="ReferenceA"/>

==As a drug target==

===CYP17A1 inhibitors===
{{Main|CYP17A1 inhibitor}}
The drug [[abiraterone acetate]], which is used to treat [[castration-resistant prostate cancer]], blocks the biosynthesis of androgens by inhibiting the CYP17A1 enzyme. Abiraterone acetate binds in the active site of the enzyme <ref>{{Cite journal|last=Fernández-Cancio|first=Mónica|last2=Camats|first2=Núria|last3=Flück|first3=Christa E.|last4=Zalewski|first4=Adam|last5=Dick|first5=Bernhard|last6=Frey|first6=Brigitte M.|last7=Monné|first7=Raquel|last8=Torán|first8=Núria|last9=Audí|first9=Laura|date=2018-04-29|title=Mechanism of the Dual Activities of Human CYP17A1 and Binding to Anti-Prostate Cancer Drug Abiraterone Revealed by a Novel V366M Mutation Causing 17,20 Lyase Deficiency|url=http://www.mdpi.com/1424-8247/11/2/37|journal=Pharmaceuticals|language=en|volume=11|issue=2|pages=37|doi=10.3390/ph11020037}}</ref> and coordinates the [[heme]] iron through its pyridine nitrogen, mimicking the subtrate.<ref name="pmid22266943">{{PDB|3ruk}}; {{cite journal | vauthors = DeVore NM, Scott EE | title = Structures of cytochrome P450 17A1 with prostate cancer drugs abiraterone and TOK-001 | journal = Nature | volume = 482 | issue = 7383 | pages = 116–9 | date = February 2012 | pmid = 22266943 | pmc = 3271139 | doi = 10.1038/nature10743 }}</ref>

Since 2014, [[galeterone]] has been in [[phase III]] [[clinical trial]]s for [[castration-resistant prostate cancer]].<ref name="Tokai2014">{{cite press release |title = Tokai Pharmaceuticals' Reformulated Galeterone Demonstrates Robust PSA Reductions in Advanced Prostate Cancer Patients | url = http://investors.tokaipharma.com/phoenix.zhtml?c=252857&p=irol-newsArticle_pf&ID=1953287 | publisher = Tokai Pharmaceuticals | date = January 29, 2014 }}</ref>

[[Ketoconazole]] is an older CYP17A1 inhibitor that is now little used. However Ketoconazole competitively inhibits CYP17A1, therefore its effectiveness will depend on the concentration of Ketoconazole. The drug abiraterone acetate, permanently disables CYP17A1, once it binds to it.

Innocrine Pharmaceutical has a selective CYP17A inhibitor called Seviteronel (VT-464) which does not require co-administration of glucocortoid therapy.   It is in clinical trials for resistant prostate cancer and breast cancer.  Innocrine's website suggests non-cancer use for VT-464 for other androgen dependent conditions such as CAH, PCOS, precocious puberty, etc.  Breast cancer trial should report out end of December 2017.

==Steroidogenesis==
{|
| [[File:Steroidogenesis.svg|thumb|none|600px|[[Steroidogenesis]], showing, at left side, both reactions of 17α-hydroxylase, and both actions of 17, 20 lyase.]]
|}

==Additional images==
<gallery>
File:Pregnenolone.svg|[[Pregnenolone]]
File:17-Hydroxypregnenolone.svg|[[17α-Hydroxypregnenolone]]
File:Progesterone.svg|[[Progesterone]]
File:17-Hydroxyprogesterone.svg|[[17α-Hydroxyprogesterone]]
File:Trimethyl steroid-nomenclature.svg|Steroid numbering
</gallery>

==See also==
{{Portal|Molecular and Cellular Biology}}
* [[Steroidogenic enzyme]]
* [[Cytochrome P450 oxidoreductase deficiency]]

==References==
{{Reflist|33em}}

==Further reading==
{{Refbegin|33em}}
* {{cite journal | vauthors = Miura K, Yasuda K, Yanase T, Yamakita N, Sasano H, Nawata H, Inoue M, Fukaya T, Shizuta Y | title = Mutation of cytochrome P-45017 alpha gene (CYP17) in a Japanese patient previously reported as having glucocorticoid-responsive hyperaldosteronism: with a review of Japanese patients with mutations of CYP17 | journal = The Journal of Clinical Endocrinology and Metabolism | volume = 81 | issue = 10 | pages = 3797–801 | date = October 1996 | pmid = 8855840 | doi = 10.1210/jcem.81.10.8855840 }}
* {{cite journal | vauthors = Miller WL, Geller DH, Auchus RJ | title = The molecular basis of isolated 17,20 lyase deficiency | journal = Endocrine Research | volume = 24 | issue = 3-4 | pages = 817–25 | year = 1999 | pmid = 9888582 | doi = 10.3109/07435809809032692 }}
* {{cite journal | vauthors = Strauss JF | title = Some new thoughts on the pathophysiology and genetics of polycystic ovary syndrome | journal = Annals of the New York Academy of Sciences | volume = 997 | issue =  | pages = 42–8 | date = November 2003 | pmid = 14644808 | doi = 10.1196/annals.1290.005 }}
* {{cite journal | vauthors = Haider SM, Patel JS, Poojari CS, Neidle S | title = Molecular modeling on inhibitor complexes and active-site dynamics of cytochrome P450 C17, a target for prostate cancer therapy | journal = Journal of Molecular Biology | volume = 400 | issue = 5 | pages = 1078–98 | date = July 2010 | pmid = 20595043 | doi = 10.1016/j.jmb.2010.05.069 }}
{{Refend}}

==External links==
* {{MeshName|CYP17A1+protein,+human}}
* {{UCSC gene info|CYP17A1}}


{{Steroid hydroxylases}}
{{Cytochrome P450}}
{{Oxygenases}}
{{Enzymes}}

[[Category:Cytochrome P450]]