Staurosporine ©

1. Discovery, producing organism23)
Staurosporine was originally discovered in 1977 from culture of Saccharothrix aerocolonigenes
starin AM-2282T during a screening program for microbial alkaloid using a chemical detection
method.1,2,3) During the past 30 years, staurosporine and related indolocarbazole natural compounds have been isolated from not only actinomycetes but also myxomycetes (slime molds),
cyanobacteria and marine invertebrates such as sponges.
In 1986, 10 years after the discovery, staurosporine was found to be a nano molar inhibitor ofprotein kinases.4,5) Staurosporine is commercially available for biochemical research.
HNN
H3C

OON

H3CO

Saccharothrix aerocolonigenes subsp.
staurosporeus AM-2282T(Lentzea albida AM-2282)

NHCH3
Staurosporine

2. Physicochemical data and structure
Pale yellow crystals. C28H26N4O3; mol wt 466.20; Sol. in DMSO, DMF. Slightly sol. in CHCl3,MeOH.
The structure and absolute configuration of staurosporine was revealed by X-ray crystallographic
analysis 6,7) and confirmed by total synthesis by Danishefsky et al.8) and an another group.
3. Biosynthesis of Staurosporine
Biosynthesis of staurosporine and rebeccamycin has been revealed by genetic and biochemicalstudies (Sanchez et al. 9,10) , Onaka et al. 11,12) and Groom et al.24) see figure).
In staurosporine biosynthsis, StaO initiates the synthesis by catalyzing L-trypthophan to imine
form of indole-3-pyruvic acid (IPA imine) and StatD then catalyzes the coupling of two IPA
imines to yield chromopyrrrolic acid(CPA). The formation of indolocarbazole core of staurosporine is catalyzed by StaP. StaP converts CPA into three indolocarbazole compounds; staurosporine aglycone (K252c), 7-hydroxy-K252-c and acrylflavin A by intramolecular C-C bondformation and oxidative decarboxylation. The presence of StaC directs formation of K252c
predominantly. StaG catalyzes a glycosidic bond formation between N-13 and C-6’ and thenStaN, a P-450 homolog, catalyzes an additional C-N bond formation between N-12 and C-2’.
These two enzymes convert Staurosporine aglycone (K252c) to 3’ O-demethyl, 4’-N-demethylstaurosporine via Holyrine A and Holyrine B. StaMA catalyzes N-metylation of 3’ O-demethyl,
4’-N-demethyl- staurosporine and StaMB catalyzes O-methylation which result in formation ofstaurosporine.

4 Biological activities
In mid-1980s , staurosporine and related indolocarbazole K-252 were shown to be nano molar
inhibitors of protein kinases Kyowa Hakko Co. The reports led many laboratories and pharmaceutical companies to find selective protein kinase inhibitors by chemical synthesis or screening of new natural products. In 1996, a bcr-abl tysorine kinase inhibitor by chemical synthesis,Gleevec, entered human clinical trial of chronic myelogenous leukaemia and was approved in2001 in USA.10)
1) Inhibition of protein kinases
Staurosporine has been use as the reference compound of many protein kinase assays. The figure
shows IC50 against 235 protein kinase assayed by Carna Biosciences Inc.22)
Following the discovery that staurosporine was a nanomolar inhibitor of protein serine/threonine
kinases such as protein kinase C 4) and also protein tyrosine kinase v-src 5), many derivatives andmimics of staurosporine and indole carbazole were made.
7-Hydroxystaurosporine (UCN-01) showed antitumor activity in mouse tumor models and entered clinical studies.14) In 2001 Gleevec targeting ABL(Abelson protein tyrosine kinase) was approved for clinical use and protein kinases have became one of the major drug targets of the 21stcentury.15)
The crystal structures of sturosporine and protein kinases, including PKC isozymes, cyclin-dependent kinases and EGF-Receptor tyrosine kinase, revealed that staurosporine overlaps wellwith the adenosine group of ATP. The lactam ring mimics the hydrogen bonding interactions ofadenine, while the glycosyl group mimics those of ribose. Staurosporine related structures suchas indolocarbazole aglycon, diindolylmaleimides and dianilinophthalamides have been derivatized and developed into selective inhibitors for pharmacologically interesting targets.15)

2) Action on Topisomerases with ATP binding site
DNA topoisomerases have been shown to be an important target of antitumor drugs or antibacterial agents. Both antitumor drugs in eukaryotes and quinolone antibiotics in prokaryotes stabilize
DNA-cleavable complex with topoisomerase. It was shown that staurosporine related structuresinduce DNA cleavable complex with mammalian topoisomerases. Semisynthetic derivatives ofK252a were potent inducer of DNA cleavable complex with Topoisomerase I, whereas rebbecamycin was a weak inducer in the same assay.16)
3) Anti-microbial and pathogenic activity
Staurosporine was shown to have weak antifungal activity since the discovery by Ōmura et al.1,2)
Later, protein Ser/Thr kinases were identified in many pathogenic organisms including mycobacteria, malaria and viruses.
Staurosporine and K-252 was found to inhibit mycobacterial growth at 5-50 μM.17)
In Plasmodium falciparum, a cyclin- nuclear division cycle dependent kinase (CDK) PfPK5, wasidentified as the first such compound not derived from humans. Staurosporine inhibited PfPK5
with IC50 at 1 μM.18) Antiviral properties of indolocarbazoles have been reported including human immunodeficiency virus, cytomegalovirus and Epstein–Barr virus.
4) Cytotoxic activity/Acute toxicity
Staurosporine showed a wide range of growth inhibition effects against cultured cells and wasextremely cytotoxic in some cases (4pM, Hela-S3, 72 hr exposure ).
Staurosporine induced apoptosis as do anticancer drugs, but via partly distinct pathways. Several cell lines are completely resistant towards different anticancer drugs, but remain sensitive
towards staurosporine-induced apoptosis. These finding encouraged further clinical trials for theuse of staurosporine derivatives in antitumor therapy.
Acute toxicity (mice, i.p.) LD50 = 6.6 mg/kg
5) Other biological activities
Staurosporine and indolocarbazole derivatives showed many other biological activities.
Anti-angiogenesis activity of staurosporine derivatives with modification in its amino sugar moiety was reported19).
Ruboxistaurin (Arxxant, LY333531) is selective inhibitor of Protein kinase C isoforms β andwas evaluated in clinical studies Ruboxistaurin has been submitted to FDA for diabetic retinopathy.20)
Other reported activities include; inhibition of smooth muscle contraction21), insecticidal activity,
hypotensive properties, inhibition of platelet aggregation, activation of macrophages, immunosuppression, inhibition of the osteoclast proton pump, neuroprotection.

Inhibitory activity of staurosporine against protein kinases 22)－ 249 －

5. References
1. [127] S. Ōmura et al., J. Antibiot. 30, 275-282 (1977)
2. [576] S. Ōmura et al., J. Antibiot. 48: 535-548 (1995) Review
3. [572] Y. Takahashi et al., Actinomycetol. 9, 19-26 (1995)
4.		
T. Tamaoki et al., Biochem. Biophys. Res. Commun. 135, 397-402 (1986)
5.		
H. Nakano et al., J. Antibiot. 40, 706-708 (1987)
6. [148] A. Furusaki et al., J. Chem. Soc., Chem. Commun. 800-801 (1978)
7. [540] N. Funato et al., Tetrahedron Lett. 35, 1251-1254 (1994)
8.		
J. T. Link et al., J. Am. Chem. Soc. 117, 552-553 (1995)
9.		
C. Sanchez et al., Chem. Biol. 9, 519-531 (2002)
10.		
C. Sanchez et al., Nat. Prod. Rep. 23, 1007-1045 (2006) Review
11.		
H. Onaka et al., J. Antibiot. 55, 1063-1071(2002)
12.		
H. Onaka Actinomycetol. 20, 62-71(2006) Review
13.		
Staurosporine is commercially available and used as a standard for kinase assays.			
IC50s reported in early era : PKCs (2.7 nM), PKA(15 nM), v-src tyrosine kinase (6nM) , EGF-R tyrosine kinase(25 nM, insulin receptor tyrosine kinase (IC50 = 61nM), phosphorylase kinase (3 nM), S6 kinase (5 nM)
14.		
I. Takahashi et al., J. Antibiot. 40, 1782-1784 (1987)
15.		
P. Cohen, Nat. Rev. Drug Discov. 1, 309-315 (2002)
16.		
Y. Yamashita et al., Biochem. 31, 12069-12075 (1992)
17.		
P. Fernandez et al., J. Bacteriology 188, 7778-7784. (2006)
18.		
S. Holton et al., Structure 11, 1329-1337 (2006)
19. [749] Z. Li et al., J. Antibiot., 53, 426-429 (2000)
20.		
http://www.lilly.com
21. [474] Y. Sasaki et al., Eur. J. Pharmacol. 202, 367-372 (1991)
22.		
Kinase profiling book by Carna Bioscience Inc.
23. [1027] H. Nakano and S. Ōmura, J. Antibiot. 62, 17-26 (2009)24.		
K. Groom et al., ChemBioChem. 12, 396-400 (2011)