To interpret the scans presented in Fig. 1 (and Fig. 2 in
ESIz) the binding of a labelled lectin to cells will shift the
signal from the position of the control curve (in gray) to the
right. An inhibitor will then interfere with lectin association
(measured in percentage of positive cells and mean fluorescence
intensity), moving the fluorescence profile back into the
direction of the control. This principle can now readily be
applied to the scans. In full accord with Table 1, the
monovalent derivative 12 was not inhibitory at this tested
concentration on VAA, whereas lactose and the two glyco-
clusters 3 and 4 reduced lectin binding with increasing potency
(Fig. 2a in ESIz). As noted previously,8 the cone-4-type
presentation showed increased reactivity relative to the
hexavalent compound in this system. This was further under-
scored by testing a different cell line, i.e. Chinese hamster
ovary (CHO) cells with defective a2,3-sialylation (Lec2
mutant12) (not shown). The tetravalent glycocluster 1 proved
most active against galectin-3 (Fig. 2b in ESIz). In addition to
the colon carcinoma cells, CHO cells with normal and reduced
levels of a2,3-sialylation and decreased b1,6-branching of
N–glycans (wild-type cells; Lec2/Lec4 mutant cells12) as well
as pancreatic carcinoma cells, in which galectin-3 can act as
competitive inhibitor against galectin-1 which induces anoikis
Interdipartimentale Misure ‘‘G. Casnati’’ for use of NMR
facilities, the Conseil Regional de Picardie for a post-doctoral
´
fellowship to FMG and Drs B. Friday and S. Namirha for
insightful discussions.
Notes and references
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Glycosci. Glycotechnol., 2006, 18, 1; (b) R. Schwartz-Albiez, in The
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H.-J. Gabius, Adv. Drug Delivery Rev., 2000, 43, 225;
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under the control of the tumor suppressor p16INK4a 13
were
,
processed, yielding comparable results. These data provide
further evidence for the cone-4-type calixarene as suitable
scaffold to hit galectin-3, irrespective of changes in the glycomic
profile. Of note, galectin-1 binding was not affected at 10 mM
sugar concentration by this calixarene (not shown), and
galectin-4 remained more sensitive to the hexa- than the
tetravalent glycoclusters (Fig. 1). The same tendency with
rather similar quantitative data was observed for galectin-9,
with optimal activity for the 2-N-substituted hexavalent 4 (not
shown), in full accord with the data from the solid-phase
assays (Table 1).
´
5 (a) P. Sorme, P. Arnoux, B. Kahl-Knutsson, H. Leffler, J. M. Rini
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and U. J. Nilsson, J. Am. Chem. Soc., 2005, 127, 1737;
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A. M. J. J. Bonvin and H.-J. Gabius, Biochim. Biophys. Acta, Gen.
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´
nez,
Overall, our results illustrate the benefit to combine core
derivatisation with conjugation of the biomimetic product to
distinct scaffolds for multivalent display. Practically, the
documented interference of galectin-3 with the pro-anoikis
effector of galectin-1 as e.g. in pancreatic cancer in vitro,13 can
be precluded by using such a selective blocking reagent, i.e.
cone-4-type calixarene with 30(or 2-N-)-substituted LacNAc.
Further tailoring the nature of the substituent to fully match
the galectin’s individual microenvironment in the contact site,
comprising Arg144, His158, Asn160, Lys176 and Trp181,5a,c
affords the possibility for iterative improvements. Using
bivalent glycophanes with/without conformational flexibility
the attained selectivity increases could then be exploited
to affect galectin-3 and its proteolytically processed form
differently.14 20-Substitution and starburst glycodendrimers
will be worthy of testing VAA,7,15 and the sulfatide headgroup
is a commendable candidate for galectin-4.4c,16 In general
terms, the presented strategy to amalgamate carbohydrate
and supramolecular chemistry can have relevance beyond
the particular lectins tested in this study.
´
´
´
,
9 F.-M. Gautier, F. Djedaıni-Pilard and C. Grandjean, Carbohydr.
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¨
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H. Kaltner, M. Lensch and
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13 (a) S. Andre, H. Sanchez-Ruderisch, H. Nakagawa, M. Buchholz,
´
J. Kopitz, P. Forberich, W. Kemmner, C. Bock, K. Deguchi,
¨
K. M. Detjen, B. Wiedenmann, M. von Knebel Doeberitz,
T. M. Gress, S.-I. Nishimura, S. Rosewicz and H.-J. Gabius, FEBS
J., 2007, 274, 3233; (b) H. Sanchez-Ruderisch, C. Fischer,
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and H.-J. Gabius, FEBS J., 2010, 277, 3552.
14 R. Leyden, T. Velasco-Torrijos, S. Andre, S. Gouin, H.-J. Gabius
and P. V. Murphy, J. Org. Chem., 2009, 74, 9010.
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´
´
´
Glycobiology, 1999, 9, 1253.
16 D. Delacour, V. Gouyer, J.-P. Zanetta, H. Drobecq, E. Leteurtre,
We thank the EC GlycoHIT program for generous
funding, the Ministero dell’Istruzione, Universita e Ricerca
(MIUR, PRIN-project no. 200858SA98), the Centro
G. Grard, O. Moreau-Hannedouche, E. Maes, A. Pons, S. Andre,
´
A. Le Bivic, H.-J. Gabius, A. Manninen, K. Simons and G. Huet,
J. Cell Biol., 2005, 169, 491.
c
6128 Chem. Commun., 2011, 47, 6126–6128
This journal is The Royal Society of Chemistry 2011