Scientific Researches On:
Betulinic Acid (Birch Bark Extract)
USA National Center for
Biotechnology Information
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61:
Bioorg Med Chem Lett. 2003 Oct
6;13(19):3137-40.
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Synthesis and cytotoxic activity of A-ring
modified betulinic acid derivatives.
You YJ,
Kim Y,
Nam NH,
Ahn BZ.
College of Pharmacy, Chungnam National University,
Taejon 305-764, South Korea.
New A-ring modified betulinic acid derivatives
having small steric hindrance were prepared and
tested for cytotoxic activity on 3 cancer cell
lines: 10 compounds showed stronger cytotoxic
activity than betulinic acid. Especially, the
compounds bearing 1-ene-3-oxo with
electron-withdrawing groups at C2 showed strong
cytotoxicity.
Publication Types:
PMID: 12951080 [PubMed - indexed for MEDLINE]
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New ursolic and betulinic derivatives as
potential cytotoxic agents.
Baglin I,
Poumaroux A,
Nour M,
Tan K,
Mitaine-Offer AC,
Lacaille-Dubois MA,
Chauffert B,
Cavé C.
Université de Bourgogne, Faculté de Pharmacie,
Unité de Molecules d'Intérêt Biologique, JE 2244,
BP 87900, 21079 Dijon Cedex, France. ibaglin@u-bourgogne.fr
Fifteen new ursolic and betulinic triterpenoids,
bearing various functionalities at C-3 and C-28
were synthesized as potential cytotoxic agents.
All compounds were obtained by a hemisynthetic
route via ursolic and betulinic acids. Preliminary
screening of these compounds on human HT 29 colon
cancer cells revealed inhibitory activity for
three of them.
Beta-D-Glucopyranosyl-3beta-hydroxyurs-12(13)-en-28-oate
1c,
3beta-3-(3-pyridyl)-prop-2-enoyloxyurs-12(13)-en-28-oic
acid 1i and the potassium salt of
3beta-cinnamoyloxylup-20(29)-en-28-oic acid 2d
demonstrated cytotoxic activity in the micromolar
range: 8.0, 45.0 and 8.0 microM, respectively.
PMID: 12943194 [PubMed - indexed for MEDLINE]
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Betulinic acid-induced programmed cell death in
human melanoma cells involves mitogen-activated
protein kinase activation.
Tan Y,
Yu R,
Pezzuto JM.
Program for Collaborative Research in the
Pharmaceutical Sciences, Department of Medicinal
Chemistry and Pharmacognosy, University of
Illinois at Chicago, Chicago, Illinois 60612, USA.
Betulinic acid, a naturally occurring triterpene
found in the bark of the white birch tree, has
been demonstrated to induce programmed cell death
with melanoma and certain neuroectodermal tumor
cells. We demonstrate currently that treatment of
cultured UISO-Mel-1 (human melanoma cells) with
betulinic acid leads to the activation of p38 and
stress activated protein kinase/c-Jun
NH(2)-terminal kinase [widely accepted
proapoptotic mitogen-activated protein kinases (MAPKs)]
with no change in the phosphorylation of
extracellular signal-regulated kinases (antiapoptotic
MAPK). Moreover, these results support a link
between the MAPKs and reactive oxygen species (ROS).
As demonstrated previously, cells treated with
betulinic acid generate ROS. Preincubation of
cells with antioxidants blocks the process of
programmed cell death, and prevents the
phosphorylation of p38 and stress activated
protein kinase/c-Jun NH(2)-terminal kinase. These
data suggest that ROS act upstream of the MAPKs in
the signaling pathway of betulinic acid. In
addition to mediating these responses, treatment
of cells with betulinic acid resulted in a gradual
depolarization of mitochondrial membrane
potential, a phenomenon established to contribute
to the induction of programmed cell death.
Interestingly, p38 was capable of partially
modulating this perturbation, and investigations
of mitochondria-associated apoptotic events
indicate no involvement of known caspases. These
data provide additional insight in regard to the
mechanism by which betulinic acid induces
programmed cell death in cultured human melanoma
cells, and it likely that similar responses
contribute to the antitumor effect mediated with
human melanoma carried in athymic mice.
Publication Types:
PMID: 12855667 [PubMed - indexed for MEDLINE]
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A key role for caspase-2 and caspase-3 in the
apoptosis induced by 2-chloro-2'-deoxy-adenosine (cladribine)
and 2-chloro-adenosine in human astrocytoma cells.
Ceruti S,
Beltrami E,
Matarrese P,
Mazzola A,
Cattabeni F,
Malorni W,
Abbracchio MP.
University of Milan and Center of Excellence for
Neurodegenerative Diseases (CEND)-Via Balzaretti
9, 20133 Milan, Italy.
Both the anticancer agent
2-chloro-2'-deoxy-adenosine (Cladribine) and its
derivative 2-chloro-adenosine induce apoptosis of
human astrocytoma cells (J Neurosci Res
60:388-400, 2000). In this study, we have analyzed
the involvement of caspases in these effects. Both
compounds produced a gradual and time-dependent
activation of "effector" caspase-3, which preceded
the appearance of the nuclear signs of apoptosis,
suggesting a temporal correlation between these
two events. Moreover, the caspase inhibitor N-benzyloxycarbonyl-Val-Ala-dl-Asp-fluoromethylketone
(fmk) suppressed both caspase-3 activation and
apoptosis induction. "Initiator" caspase-9 and
caspase-8 were only marginally activated at later
times in the apoptotic process. Accordingly, at
concentrations that selectively inhibit these
caspases, neither N-benzyloxycarbonyl-Leu-Glu-His-Asp-fmk
nor N-benzyloxycarbonyl-Ile-Glu-Thr-Asp-fmk could
prevent adenosine analog-induced cell death. To
definitively rule out a role for the caspase-9/cytochrome
c-dependent mitochondrial pathway of cell death,
neither adenosine analog had any effect on
mitochondrial membrane potential, which was
instead markedly reduced by other apoptotic
stimuli (e.g., deoxyribose, NaCN, and betulinic
acid). Consistently, although the latter triggered
translocation of mitochondrial cytochrome c to the
cytoplasm, no cytosolic accumulation of cytochrome
c was detected with adenosine analogs. Conversely,
1 to 7 h after addition of either adenosine analog
(i.e., before the appearance of caspase-3
activation), caspase-2 activity was surprisingly
and markedly increased. The selective caspase-2
inhibitor N-benzyloxy
carbonyl-Val-Asp-Val-Ala-Asp-fmk significantly
reduced both adenosine analogs-induced caspase-2
activation and the associated cell death. We
conclude that adenosine analogs induce the
apoptosis of human astrocytoma cells by activating
an atypical apoptotic cascade involving caspase-2
as an initiator caspase, and effector caspase-3.
Therefore, these compounds could be effectively
used in the pharmacological manipulation of tumors
characterized by resistance to cell death via
either the mitochondrial or caspase-8/death
receptor pathways.
Publication Types:
PMID: 12761355 [PubMed - indexed for MEDLINE]
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[Epimerization of hydroxyl group in the lupan
series of triterpenes]
[Article in Russian]
Symon AV,
Kaplun AP,
Vlasenkova NK,
Gerasimova GK,
Shon le B,
Litvin EF,
Kozlova LM,
Surkova EL,
Shvets VI.
Lomonosov State Academy of Fine Chemical
Technology, pr. Vernadskogo 86, Moscow, 119571
Russia.
Two methods of obtaining of 3 alpha-betulinic acid
and related compounds from their 3 beta-epimers
were studied: the reaction of bimolecular
substitution and the stereoselective reduction of
3-ketoderivatives. The substitution of acyloxy by
formyloxy group in 3-O-tosyllupeol or of the
betulin hydroxyl by benzoyloxy group resulted only
in delta 2, 3-elimination products, with none of
the expected products of bimolecular substitution
being found. The catalytic hydrogenation of
betulonic acid over Raney nickel resulted only in
reduction of the isopropenyl double bond, whereas
the use of 5% Ru/C gave a 60:40 mixture of epimers
of dihydrobetulinic acid. Practically the same
mixture of betulinic acid epimers was obtained
when reducing betulonic acid with L-Selectride.
The cytotoxic activity of 3 alpha-betulinic acid
increased toward melanoma Bro cells and decreased
toward melanoma MS cells.
Publication Types:
PMID: 12708322 [PubMed - indexed for MEDLINE]
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New cytotoxic lupane triterpenoids from the
twigs of Coussarea paniculata.
Prakash Chaturvedula VS,
Schilling JK,
Johnson RK,
Kingston DG.
Department of Chemistry, M/C 0212, Virginia
Polytechnic Institute and State University,
Blacksburg, Virginia 24061-0212, USA.
Bioassay-guided fractionation of a CH(2)Cl(2)-MeOH
extract of the twigs of Coussarea paniculata using
a yeast-based assay for potential DNA-damaging
agents resulted in the isolation of three new
lupane triterpenoids, 1-3, in addition to eight
known triterpenoids, lupeol (4), lupeyl acetate
(5), betulin (6), betulinic acid (7),
3-epi-betulinic acid (8), 3-epi-betulinaldehyde
(9), oleanolic acid (10), and ursolic acid (11).
The structures of the new compounds were
established as lup-20(29)-en-3beta,25-diol (1),
lup-20(29)-en-11alpha-ol-25,3beta-lactone (2), and
3-deoxybetulonic acid (3), on the basis of
extensive 1D and 2D NMR spectroscopic data
interpretation and chemical conversion.
Publication Types:
PMID: 12662105 [PubMed - indexed for MEDLINE]
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Betulinic acid-induced Mcl-1 expression in
human melanoma--mode of action and functional
significance.
Selzer E,
Thallinger C,
Hoeller C,
Oberkleiner P,
Wacheck V,
Pehamberger H,
Jansen B.
Department of Clinical Pharmacology, Section of
Experimental Oncology and Molecular Pharmacology,
University Hospital Vienna, Austria. Edgar.Selzer@AKH-Wien.ac.at
BACKGROUND: Currently there is no information on
the regulation of expression and physiological
role of the anti-apoptotic protein Mcl-1 in cells
of the melanocytic lineage. This study
investigates the regulation and expression of
Mcl-1 in human melanoma cells, which was recently
found to be induced by betulinic acid, a compound
with anti-melanoma and apoptosis-inducing
potential. MATERIALS AND METHODS: Mcl-1
phosphorthioate antisense oligonucleotides were
used to investigate the effect of downregulating
the expression of Mcl-1. Regulation of Mcl-1
expression was analyzed with the specific
PI3-kinase inhibitors LY294002 and wortmannin and
the inhibitor of MAP-kinase activation, PD98059.
Western blot analysis was performed with anti
ERK1/2, Mcl-1, Bak, Bcl-x and Bax antibodies.
Activation status of PI-3 kinase and MAP-kinase
pathways was investigated using phospho-Akt and
phosphorylation-state independent Akt as well as
phospho-MAP kinase, phospho-MEK and
phospho-GSK-3alpha/beta antibodies. RESULTS:
Upregulation of Mcl-1 in human melanoma cells by
betulinic acid is mediated via a
signal-transduction pathway that is inhibited by
LY294002 and wortmannin. Betulinic acid-induced
phosphorylation and activation of the Akt protein
kinase was inhibited by LY294002. The inhibitor
PD98059 reduced expression levels of Mcl-1 in
melanoma cells and this effect was counteracted by
betulinic acid. Downregulation of Mcl-1 by
antisense oligodeoxynucleotides in combination
with betulinic treatment led to a synergistic
effect regarding growth inhibition. CONCLUSIONS:
These results suggest that in human melanoma cells
Mcl-1 is (i) of functional relevance for survival
and (ii) subject to dual regulation by the MAP-
kinase pathway and a pathway involving protein
kinase B/Akt, the latter of which is modulated in
response to betulinic acid. This study provides an
experimental foundation for future therapeutic
strategies using anti-Mcl-1 antisense
oligonucleotides in human melanoma.
Publication Types:
PMID: 12606824 [PubMed - indexed for MEDLINE]
PMCID: PMC2039966
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23-Hydroxybetulinic acid-mediated apoptosis is
accompanied by decreases in bcl-2 expression and
telomerase activity in HL-60 Cells.
Ji ZN,
Ye WC,
Liu GG,
Hsiao WL.
Department of Pharmacology, China Pharmaceutical
University, 210009, Nanjing, China
23-Hydroxybetulinic acid, a derivative of
betulinic acid, was investigated for its apoptotic
effect and the associated telomerase activity in
human leukemia HL-60 cells. Apoptosis and bcl-2
were determined by flow cytometry analysis. A PCR-based
telomeric repeat amplification protocol assay was
used to detect telomerase activity. Results showed
that 23-hydroxybetulinic acid induced growth
arrest and apoptotic cell death in HL-60 cells.
The apoptotic events were associated with
concurrent down-regulation of bcl-2 and the
telomerase activity. Our data suggest that
23-hydroxybetulinic acid may be a potential
cytotoxic agent for treatment of cancer.
Publication Types:
PMID: 12409140 [PubMed - indexed for MEDLINE]
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[Are mitochondria targets of anticancer drugs
responsible for apoptosis?]
[Article in French]
Marchetti P,
Mortier L,
Beauvillain V,
Formstecher P.
Laboratoire de biologie cellulaire, Inserm U. 459,
Faculté de médecine, 1, place Verdun, 59045 Lille
cedex.
The vast majority of both chemical and physical
anticancer treatments act through the induction of
apoptotic cell death in vitro and in vivo. In
numerous experimental systems, the apoptotic
processes can be divided into three different
phases. In the first one, multiple pro-apoptotic
signal transduction pathways (e.g. P53, ROS
production, etc.) are activated by various factors
including anti cancer drugs. This first step is
followed by an intermediate phase in which
pro-apoptotic signals converge to mitochondria
which in turn can finally trigger the last
degradation phase of apoptosis. Consequently,
mitochondria, play a pivotal role in the executive
phase of apoptosis and could represent a novel
attractive target for pro-apoptotic drugs. Indeed,
unlike conventional anti tumour drugs which
trigger pro-apoptotic signal transduction pathways
upstream mitochondria, several compounds were
shown to act directly on mitochondria to induce
apoptosis. These drugs include betulinic acid,
lonidamine, arsenic trioxide and two retinoids
like CD437/AHPN and fenretinide/4-HPR. This review
summarizes new data concerning these drugs
targetted to mitochondria and highlights the new
perspective they may offer in cancer therapy.
Publication Types:
PMID: 12147443 [PubMed - indexed for MEDLINE]
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Luteolin, an emerging anti-cancer flavonoid,
poisons eukaryotic DNA topoisomerase I.
Chowdhury AR,
Sharma S,
Mandal S,
Goswami A,
Mukhopadhyay S,
Majumder HK.
Molecular Parasitology Laboratory, Indian
Institute of Chemical Biology, 4 Raja S.C. Mullick
Road, Kolkata 700 032, India.
Luteolin, a naturally occurring flavonoid, is
abundant in our daily dietary intake. It exhibits
a wide spectrum of pharmacological properties, but
little is known about its biochemical targets
other than the fact that it induces topoisomerase
II-mediated apoptosis. In the present study, we
show that luteolin completely inhibits the
catalytic activity of eukaryotic DNA topoisomerase
I at a concentration of 40 microM, with an IC50 of
5 microM. Preincubation of enzyme with luteolin
before adding a DNA substrate increases the
inhibition of the catalytic activity (IC50=0.66
microM). Treatment of DNA with luteolin before
addition of topoisomerase I reduces this
inhibitory effect. Subsequent fluorescence tests
show that luteolin not only interacts directly
with the enzyme but also with the substrate DNA,
and intercalates at a very high concentration
(>250 microM) without binding to the minor groove.
Direct interaction between luteolin and DNA does
not affect the assembly of the enzyme-DNA complex,
as evident from the electrophoretic mobility-shift
assays. Here we show that the inhibition of
topoisomerase I by luteolin is due to the
stabilization of topoisomerase-I DNA-cleavable
complexes. Hence, luteolin is similar to
camptothecin, a class I inhibitor, with respect to
its ability to form the topoisomerase I-mediated
'cleavable complex'. But, unlike camptothecin,
luteolin interacts with both free enzyme and
substrate DNA. The inhibitory effect of luteolin
is translated into concanavalin A-stimulated mouse
splenocytes, with the compound inducing
SDS-K+-precipitable DNA-topoisomerase complexes.
This is the first report on luteolin as an
inhibitor of the catalytic activity of
topoisomerase I, and our results further support
its therapeutic potential as a lead anti-cancer
compound that poisons topoisomerases.
Publication Types:
PMID: 12027807 [PubMed - indexed for MEDLINE]
PMCID: PMC1222798
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Differentiation- and apoptosis-inducing
activities by pentacyclic triterpenes on a mouse
melanoma cell line.
Hata K,
Hori K,
Takahashi S.
Akita Research Institute of Food & Brewing (ARIF),
4-26 Sanuki, Araya-machi, Akita 010-1623, Japan.
In a study to investigate the relationship between
the chemical structure and the
differentiation-inducing activity of pentacyclic
triterpenes, several lupane, oleanane, and ursane
triterpenes were prepared and their effects on B16
2F2 melanoma cell differentiation and growth were
examined. Eleven lupane triterpenes used in this
study acted on the melanoma cells as a melanogen,
but no induction of melanogenesis of B16 2F2 cells
by oleanane and ursane was detected. The
differences at C-17 of the lupane series and
acetylation of the OH group at C-3 did not
markedly influence their activities. However, the
ED(50) value for up-regulation of melanin
biosynthesis was markedly decreased by the
oxidation of the OH group at C-3 of lupeol (1).
Betulinic acid (11), its methyl ester (12),
lup-28-al-20(29)-ene-3beta-ol (9), and
lup-28-al-20(29)-en-3-one (10) inhibited B16 2F2
cell proliferation by induction of apoptosis.
These findings suggested that the carbonyl group
at C-17 might be essential for the apoptotic
effects of these compounds on B16 2F2 cells.
PMID: 12027734 [PubMed - indexed for MEDLINE]
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Preparation of a 24-nor-1,4-dien-3-one
triterpene derivative from betulin: a new route to
24-nortriterpene analogues.
Deng Y,
Snyder JK.
Department of Chemistry, Boston University, 590
Commonwealth Avenue, Boston, Massachusetts 02215,
USA.
A new route to 24-nortriterpene derivatives with
2-hydroxy-Delta(1,4)-cyclohexadien-3-one A-rings
from triterpene precursors has been demonstrated
beginning with betulin to prepare derivatives of
betulinic acid. The key steps in the
transformation are a Suárez cleavage of the A-ring
with a subsequent SmI(2)-mediated pinacol-type
coupling to reclose the A-ring following removal
of the C-24 carbon by oxidative cleavage.
PMID: 11975539 [PubMed - indexed for MEDLINE]
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Betulinic acid sensitization of low pH adapted
human melanoma cells to hyperthermia.
Wachsberger PR,
Burd R,
Wahl ML,
Leeper DB.
Department of Radiation Oncology, Kimmel Cancer
Center and Thomas Jefferson University,
Philadelphia, PA 19107, USA. phyllis.wachsberger@mail.tju.edu
Betulinic acid is a known inducer of apoptosis in
human melanoma that is most effective under
conditions of low pH. It was hypothesized that
betulinic acid, in combination with acute
acidification and/or hyperthermia, would induce
higher levels of apoptosis and cytotoxicity in low
pH-adapted human melanoma cells than in cells
grown at pH 7.3. DB-1 human melanoma cells,
adapted to a tumour-like growth pH of 6.7, were
exposed to hyperthermia (2h at 42 degrees C)
and/or betulinic acid (4-10 microg/ml) and
compared with cells grown at a physiological pH of
7.3 or after acute acidification from pH 7.3-6.3
or pH 6.7-6.3. Betulinic acid induced higher
levels of apoptosis and cytotoxicity in low
pH-adapted cells than in cells grown at pH 7.3, as
measured by the terminal deoxynucleotidyl
transferase (TdT) DNA fragmentation assay (TUNEL),
the MTS cell viability assay, and single cell
survival. Acute acidification of low pH adapted
cells rendered them more susceptible to betulinic
acid-induced apoptosis and cytotoxicity. In the
presence of hyperthermia at 42 degrees C for 2 h,
cells grown at pH 7.3 were not sensitized to heat
killing by betulinic acid, whereas cells grown at
pH 7.3 and acutely acidified to pH 6.3, cells
adapted to growth at pH 6.7 and cells adapted to
growth at pH 6.7 and acutely acidified to pH 6.3
were all similarly sensitized to heat killing by
betulinic acid, with survival values of 5, 9 and
2%, respectively. It is concluded that betulinic
acid may be useful in potentiating the therapeutic
efficacy of hyperthermia as a cytotoxic agent in
acidotic areas of tumours with minimal effect in
normal tissues growing at pH 7.3.
Publication Types:
PMID: 11911485 [PubMed - indexed for MEDLINE]
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Development of C-20 modified betulinic acid
derivatives as antitumor agents.
Kim JY,
Koo HM,
Kim DS.
The Program for Collaborative Research in
Pharmaceutical Science and the Department of
Medicinal Chemistry and Pharmacognosy, College of
Pharmacy, University of Illinois at Chicago,
60612, USA.
Chemical modifications were performed on C-20
position of betulinic acid for a
structure-activity relationship study. The
evaluation of the compounds using human colon
carcinoma HCT-116, human prostate adenocarcinoma
PC3, and human melanoma cell lines M14-MEL,
SK-MEL-2, and UACC-257 did not show any selective
cytotoxicity towards melanoma cells. The results
from both MTT reduction assay and SRB staining
assay were comparable that no remarkable
differences in cytotoxicity profile of the
compounds were noticed. The C-20 position was
found to be sensitive to the size and the electron
density of the substituents in retaining the
cytotoxicity of betulinic acid and was found to be
undesirable position to derivatize.
PMID: 11527742 [PubMed - indexed for MEDLINE]
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The Bax/Bcl-2 ratio determines the
susceptibility of human melanoma cells to CD95/Fas-mediated
apoptosis.
Raisova M,
Hossini AM,
Eberle J,
Riebeling C,
Wieder T,
Sturm I,
Daniel PT,
Orfanos CE,
Geilen CC.
Department of Dermatology, University Medical
Center Benjamin Franklin, Free University of
Berlin, Germany.
Defective cytochrome c release and the resulting
loss of caspase-3 activation was recently shown to
be essential for the susceptibility of human
melanoma cells to CD95/Fas-induced apoptosis.
Cytochrome c release from mitochondria is
regulated by the relative amounts of
apoptosis-promoting and apoptosis-inhibiting Bcl-2
proteins in the outer membrane of these
organelles. The assignment of Bax/Bcl-2 ratios by
quantitative Western blotting in 11 melanoma cell
populations revealed a relation to the
susceptibility to CD95-mediated apoptosis. We
could show that a low Bax/Bcl-2 ratio was
characteristic for resistant cells and a high Bax/Bcl-2
ratio was characteristic for sensitive cells. Low
Bax expression was not a consequence of mutations
in the p53 coding sequence. The Bax/Bcl-2 ratio
was also in clear correlation with sensitivity to
another cell death inducer, N-acetylsphingosine.
Furthermore, Bcl-2 overexpression abolished
apoptosis triggered by both apoptotic stimuli,
confirming the critical role of the Bax/Bcl-2
ratio as a rheostat that determines the
susceptibility to apoptosis in melanoma cells by
regulating mitochondrial function. Interestingly,
some chemotherapeutics lead to the activation of
death pathways by CD95L upregulation, ceramide
generation, direct activation of upstream caspases,
or upregulation of proapoptotic genes. Taken
together, these signals enter the apoptotic
pathway upstream of mitochondria, resulting in
activation of this central checkpoint. We
therefore assumed that apoptosis deficiency of
malignant melanoma can be circumvented by drugs
directly influencing mitochondrial functions. For
this purpose we used betulinic acid, a cytotoxic
agent selective for melanoma, straightly
perturbing mitochondrial functions. In fact,
betulinic acid induced mitochondrial cytochrome c
release and DNA fragmentation in both
CD95-resistant and CD95-sensitive melanoma cell
populations, independent of the Bax/Bcl-2 ratio.
Publication Types:
PMID: 11511312 [PubMed - indexed for MEDLINE]
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Betulinic acid reduces ultraviolet-C-induced
DNA breakage in congenital melanocytic naeval
cells: evidence for a potential role as a
chemopreventive agent.
Salti GI,
Kichina JV,
Das Gupta TK,
Uddin S,
Bratescu L,
Pezzuto JM,
Mehta RG,
Constantinou AI.
Department of Surgical Oncology, College of
Medicine, University of Illinois at Chicago,
60612, USA. geosalti@uic.edu
Melanoma transformation progresses in a multistep
fashion from precursor lesions such as congenital
naevi. Exposure to ultraviolet (UV) light promotes
this process. Betulinic acid (BA) was identified
by our group as a selective inhibitor of melanoma
that functions by inducing apoptosis. The present
study was designed to investigate the effect of BA
and UV-C (254 nm) on cultured congenital
melanocytic naevi (CMN) cells, using the
single-cell gel electrophoresis (comet) assay to
detect DNA damage. Exposure to UV light induced a
1.7-fold increase in CMN cells (P = 0.008) when
compared with controls. When a p53 genetic
suppressor element that encodes a dominant
negative polypeptide (termed GSE56) was introduced
into the CMN cells, the transfected cells were
more sensitive to UV-induced DNA breakage. This
suggests that p53 can protect against UV-induced
DNA damage and subsequent melanoma transformation.
Pretreatment with BA (3 microm) for 48 h resulted
in a 25.5% reduction in UV-induced DNA breakage in
the CMN cells (P = 0.023), but no changes were
observed in the transfected cells. However,
Western blot analysis revealed no changes in the
p53 or p21 levels in BA-treated cells, suggesting
that BA might mediate its action via a non-p53
pathway. These data indicate that BA may have an
application as a chemopreventive agent in patients
with congenital naevi.
Publication Types:
PMID: 11333133 [PubMed - indexed for MEDLINE]
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Microbial transformations of the antimelanoma
agent betulinic acid.
Kouzi SA,
Chatterjee P,
Pezzuto JM,
Hamann MT.
Department of Pharmaceutics and Medicinal
Chemistry, School of Pharmacy and Health Sciences,
University of the Pacific, Stockton, California
95211, USA. skouzi@uop.edu
Microbial transformation studies of the
antimelanoma agent betulinic acid (1) were
conducted. Screening experiments showed a number
of microorganisms capable of biotransforming 1.
Three of these cultures, Bacillus megaterium ATCC
14581, Cunninghamella elegans ATCC 9244, and Mucor
mucedo UI-4605, were selected for preparative
scale transformation. Bioconversion of 1 with
resting-cell suspensions of phenobarbital-induced
B. megaterium ATCC 14581 resulted in the
production of the known betulonic acid (2) and two
new metabolites:
3beta,7beta-dihydroxy-lup-20(29)-en-28-oic acid
(3) and 3beta,6alpha,
7beta-trihydroxy-lup-20(29)-en-28-oic acid (4).
Biotransformation of 1 with growing cultures of C.
elegans ATCC 9244 produced one new metabolite
characterized as 1beta,3beta,
7beta-trihydroxy-lup-20(29)-en-28-oic acid (5).
Incubation of 1 with growing cultures of M. mucedo
UI-4605 afforded metabolite 3. Structure
elucidation of all metabolites was based on NMR
and HRMS analyses. In addition, the antimelanoma
activity of metabolites 2-5 was evaluated against
two human melanoma cell lines, Mel-1 (lymph node)
and Mel-2 (pleural fluid).
Publication Types:
PMID: 11141108 [PubMed - indexed for MEDLINE]
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p53-independent upregulation of KILLER/DR5
TRAIL receptor expression by glucocorticoids and
interferon-gamma.
Meng RD,
El-Deiry WS.
Laboratory of Molecular Oncology and Cell Cycle
Regulation, Howard Hughes Medical Institute,
Philadelphia, Pennsylvania, 19104, USA.
KILLER/DR5 is a death-domain-containing
proapoptotic receptor that binds to the cytotoxic
ligand TRAIL. It was originally reported that
induction of KILLER/DR5 mRNA following DNA damage
was p53-dependent, but some drugs that induce
apoptosis can upregulate KILLER/DR5 mRNA
expression in cell lines with mutated p53. We
further extend those findings by classifying the
capability of various apoptosis-inducing drugs to
increase the expression of KILLER/DR5 mRNA in a
p53-independent manner. beta-Lapachone, a
topoisomerase inhibitor, increased KILLER/DR5 mRNA
in colon cancer cell lines with wild-type p53 but
not with mutant p53. In contrast, betulinic acid,
a novel chemotherapeutic compound, induced
apoptosis and KILLER/DR5 mRNA in melanoma and
glioblastoma cells through a p53-independent
mechanism. The synthetic glucocorticoid
dexamethasone elevated KILLER/DR5 mRNA in
glioblastoma, ovarian cancer, and colon cancer
cell lines with mutant p53 undergoing apoptosis,
and this induction was inhibited by the
transcriptional inhibitor actinomycin D. Although
another glucocorticoid, prednisolone, also induced
apoptosis, it did not increase KILLER/DR5 mRNA.
Finally, the cytokine interferon-gamma (IFN-gamma)
induced apoptosis and KILLER/DR5 in cell lines
with mutant p53, and the induction of KILLER/DR5
mRNA by IFN-gamma was delayed in cells lacking
wild-type STAT1, a transcription factor implicated
in IFN-gamma signaling. Similarly, the induction
of KILLER/DR5 mRNA by the cytokine TNF-alpha was
also delayed in cell lines with mutated STAT1.
These findings suggest that KILLER/DR5 may play a
role in p53-independent apoptosis induced by
specific drugs and warrants further investigation
as a novel target for chemotherapy of tumors
lacking wild-type p53. Copyright 2001 Academic
Press.
Publication Types:
PMID: 11139340 [PubMed - indexed for MEDLINE]
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Betulinic acid induces apoptosis through a
direct effect on mitochondria in neuroectodermal
tumors.
Fulda S,
Debatin KM.
University Children's Hospital, Ulm, Germany.
BACKGROUND AND PROCEDURE: We identified BetA as a
new cytotoxic agent active against neuroectodermal
tumor cells including neuroblastoma,
medulloblastoma, glioblastoma and Ewing sarcoma
cells, representing the most common solid tumors
of childhood. RESULTS: BetA induced apoptosis by a
direct effect on mitochondria independent of
accumulation of wild-type p53 protein and
independent of death-inducing ligand/receptor
systems such as CD95. Mitochondrial perturbations
on treatment with BetA resulted in the release of
soluble apoptogenic factors such as cytochrome c
or AIF from mitochondria into the cytosol, where
they induced activation of caspases.
Overexpression of the anti-apoptotic proteins
Bcl-2 or Bcl-X(L) that blocked loss of the
mitochondrial membrane potential and cytochrome c
release from mitochondria also conferred
resistance to BetA. Most importantly, BetA
exhibited potent antitumor activity on
neuroblastoma cells resistant to CD95- or
doxorubicin-triggered apoptosis and on primary
tumor cells from patients with neuroectodermal
tumors. CONCLUSIONS: Thus, BetA may be a promising
new agent in the treatment of neuroectodermal
tumors including neuroblastoma in vivo. Copyright
2000 Wiley-Liss, Inc.
Publication Types:
PMID: 11107130 [PubMed - indexed for MEDLINE]
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Biotransformation of the antimelanoma agent
betulinic acid by Bacillus megaterium ATCC 13368.
Chatterjee P,
Kouzi SA,
Pezzuto JM,
Hamann MT.
Department of Basic Pharmaceutical Sciences,
College of Pharmacy, University of Louisiana at
Monroe, Monroe, Louisiana 71209, USA.
Microbial transformation of the antimelanoma agent
betulinic acid was studied. The main objective of
this study was to utilize microorganisms as in
vitro models to predict and prepare potential
mammalian metabolites of this compound.
Preparative-scale biotransformation with
resting-cell suspensions of Bacillus megaterium
ATCC 13368 resulted in the production of four
metabolites, which were identified as
3-oxo-lup-20(29)-en-28-oic acid,
3-oxo-11alpha-hydroxy-lup-20(29)-en-28-oic acid,
1beta-hydroxy-3-oxo-lup-20(29)-en-28-oic acid, and
3beta,7beta,
15alpha-trihydroxy-lup-20(29)-en-28-oic acid based
on nuclear magnetic resonance and high-resolution
mass spectral analyses. In addition, the
antimelanoma activities of these metabolites were
evaluated with two human melanoma cell lines,
Mel-1 (lymph node) and Mel-2 (pleural fluid).
Publication Types:
PMID: 10966400 [PubMed - indexed for MEDLINE]
PMCID: PMC92230
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