TZPS- August 1987 [Vol. S] Frielle, T.. Bdanowski. M. A.. Bennet. C. D., Raids, E., Diehl,.R. E., &mford; R. A., Slater, E. E., Sigal, I. S., Caron, M. G., Lefkowitz. R. 1. and Strader. ’ C. D. (1986) Nature 32i, 75-79 Yarden, Y., Rodriguez, H., Wong, S. K. F.. Brandt, D. R., May, D. C., Bumier, J., Harkins, R. N., Chen, F. Y., Ramachandran, J., Ulrich, A. and Ross, E. M. (1986) Proc. Natl Acad. Sci. USA 83,679%6799 Kubo, T., Fukuda, K., Mikami, A., Maeda, A., Takahashi, H., Mishina, M., Haga. T., Haga, K., Ichiyama, A., Kangawa, K., Kujima, M.: Matsuo, H., Mirose, T. and Numa, S. (1986) Nature 323,411-416 Spiegel, A. M. (1987) Mol. Cell. Endocrinol. 49, l-16 Ccchince, J., Stengel, D., Woo, L. C. S. and Bimbaumer, L. (lip86) FEBS Lett. 207,187-192 Hildebrandt, J. D., Codina, J., Rosenthal, W., Bimbaumer, L., Neer, E. I.,
303
13
14 15 16 17
Yamazaki, A. and Bitensky, M. W. (1985) J. Biol. Chem. 260,14867-14872 Gilman, A. G. (1984) Cell 36,577-579 Smigel, M. D. (1986) 1. Biol. Chem. 261, 1976-1982 Pfeuffer, E., Dreher, R. M., Metzger, H. 2nd Pfeutter, T. (1985) Pmt. Nat! Acad. Sci. USA 82,3086-3090 Pfeuffer, E., Mollner, S. and Pfeuffer, T. (1985) EMBO 1. 4,3675-3679 Gilman, A. G. Annu. Rev. Biochem. (ii press) Arad, H., Rosenbusch. 1. and Levitzki. A. (1984) Proc. Nat1 Acid. Sci. USA 85) 6579-6583 Stadel, J. M., Shorr, R. G. L., Limbird, L. E. and Lefkowih, R. J. (1981) J. BioJ. Chem. 256,8718-8723 Cassel, D. and Selinger, 2. (1976) Biochim. Biophys. Actu 452,3829-3835 Levitzki, A. (1980) FEBS Left. 115.9-10 Arad, H. and Levitzki, A. (1979) Mol. Phannacol. 16,748-756 Tolkovsky, A. M. and Levitzki, A. (1978)
Biochemisty 17,3795-3810 18 Pedersen, S. E. and Ross, E. M. (1982) Proc. NatJ Acad. Sci. USA 79: 7228-7232 19 Hekman, M.. Feder, D., Keenan, A. K., Gal. A., Pfeuffer, T., Hebnreich, E. J. M. and Lwitzki, A. (1984) EMBO J. 3,33393%5 20 Tolkovsky, A. M. and Levitzki, A. (1981) J. Cyclic NItcJeotide Res. 1, 139-150 21 To!kcvs&, A. M., Braun, S. and Levitzki, A. (1982) Proc. NatJ Acad. Sci. USA 79,213-217 22 Levitzki, A. (1984) J. Recept. Res. 4,399409 23 Levihki, A. (1987) FEBS Left. 211,1X3118 24 Marbach, I., Schiloach, J. and Levitzki, A. J. BioJ. Chem. (ii press) 25 Sibley, D. R, Strasser, R H., Benovic, J. L., Daniel, K. and Lefkowitz, R. J. (1987) Proc. NutJ Acud. Sci. USA 83, 3408-3412 26 Nukaita, T., Mishina, M. and Numa, S. (1987) FEBS Left. 211, 5-9
emphysema had just begun. Substantial progress has since been made in evaluating the natural inhibitors. Genetically engineered ~~14’1 has undergone extensive pharmacokinetic studies in humDiane Amy Trainor ans. Eglin C has proved effective in experimental animal models of Several new series of very potent, selective inhibitors of human neutrophil emphysema Without causing any deleterious side effects. elastase U-INEI, an enzyme implicated as a pathogenic agent in pulmonary emphysema, have recently been reported. Diane Amy Trainor discusses the The low molecular weight synthetic inhibitors available in preIimina y pharmacological evaluation of several of these new compounds in animal models of lung injury, which indicates that they have the necessary 1983 were not selective and exhibited toxic side effects3. There has profile to properly evaluate the protease-anti-protease hypothesis of been a flurry of activity in this emphysema in the clinic, area of research in the past few Elastases are possibly the most years. Several very pctent, selecHowever, two conditions could destructive enzymes in the body, tive HNE inhibitors have emerged disturb this delicate enzymehaving the ability to degrade and the pharmacological activity inhibitor (E-I) balance: a genetic many connective tissue compodefect leading to a decrease in OLD- of several of them has been reported. PI; or the suggested oxidative nents. Human neutrophil elastase destruction of ar&‘I by, for exam(HNE), in particular, has been HNE inhibitor design implicated as a pathogenic agent ple, cigarette smoke. The resulting The design of potent synthetic in a number of human disease protease-anti-protease imbalance inhibitors of HNE requires a states, and notably in pulmonary in the lung is believed to be detailed understanding of the emphysemal. responsible for the pathogenesis catalytic machinery used for of emphysema. Emphysema is defined as a amide bond cleavage4+. HNE is a condition of the lung characterSeveral approaches for the treatserine protease having a catalytic ment of emphysema have been ized by abnormal, permanent triad consisting of three amino suggested. Currently, the most enlargement of airspaces distal to acids; aspartic acid, histidine and the terminal bronchioles, accomattractive approach is to restore serine. This triad facilitates the the enzymeinhibitor balance panied by destruction of their formation of an E-I tetrahedral by supplementing the elastase walls without obvious fibrosis*. adduct, a key intermediate in the inhibitory capacity of the lung HNE is found in the azurophilic cleavage process (Fig. la). with: (1) excess natural inhibitor granules of the human polySynthetic inhibitors are gener(~~4); (2) other naturally occurmorphonuclear leukocytes. Extraally designed to interfere with the ring high molecular weight procellular HNE released from the formation of this adduct and can tease inhibitors (e.g. eglin C); or leukocytes is usually inhibited by bind to the enzyme in a reversible excess anti-protease, primarily Lyl- (3) low molecular weight synthetic (covalent or non-covalent) or irreinhibitors of HNE. An extensive inhibitor (al-PI). proteinase versible fashion (see Ref. 3). It review of the relative merits of remains to be seen if there will be these various approaches and signirlcant differences in vivo. their therapeutic potentiai was Diane Amy Trarainor is Senior Research The synthetic inhibitors can be presented in 19833. At that time, Chemist in the Medicinal Chemistry Departgrouped into two structural types: studies with q-PI and eglin C in ment ut Stuart Pharmaceuticals, Division of peptidic or heterocyclic. experimental animal models of ICI Americas, Wilmington, DE 19899, USA.
Synthetic inhibitors of human neutrophil elastase
@ 1967, ELscvlerPublications. Cambridge
0165 - 6147/67/IM.W
2X’S - August 1987 [Vol. 83
304 TABLEI. F’qtkficinhfbftors ofHLE Compoundaad sbuchwe
Ref. Reversible
12
7
Q
8
&=3.5X
Qr
loann
9
Ki=g.ox 169M
10
--h--&-N
Chforomethyl ketones
sa
-Al&-Me---h--N
frrevewibfe
a
Ml]=
320 M-%-’
3
Sulfonata salts
O ‘:
3 N-us-+ '0
k& = 929 M-W
14
Latentisocyanates 15
Peptidic, reversibIe inhibitm
of
Four new dasses of potent, reversible, peptidic inhibitors of HNE have been reported: the
peptidyl boronic acid$, trifluoromethyl ketones (TFMKj7, aldehydessn9and tx-keto esters” (Table I). The latter three contain an electrophilic carbonyl and were de-
signed to form reversible covalent adducts with the enzyme. The trifluoromethyl ketones are the most potent synthetic inhibitor of HNE reportedtodate{& = 4.0 X l@" M). Kinetic anaIysis of these fluorinated ketones suggests that these compounds are transition state analog inhibitors of HNE*‘. The enhanced electrophiicity of the fluorinated ketone carbonyl facilitates the enzyme-catalysed addition of the active site serine to the ketone carbonyl to form a stable hemiketal adduct (Fig. lb). The aldehydes and lu-keto esters are believed to inhibit HNE in a similar manner. The aldehydes are very potent, selective inhibitors of HNII. The rw-ketoesters span the active site of HNE and are considerably more potent than the corresponding ol-keto acids. Additional binding with the S’ subsites of HNE and H-bonding of the ester carbony with the histidine N-H, apparently contributes to the overall tight binding of the cw-ketoesters to HNE. The use of boronic acids as transition state analog inhibitors of serine proteases was introduced by Koehler and Lienhard in 1971. The mechanism of inhibition of the serine protease subtilisin by phenylethane boronic acid was determined by the X-ray crystal structure of the E-I complex, which revealed that the boronic acid inhibitor bound as a tetrahedral covalent adduct with the active site serine-OH (Fig. lb). A boronic acid analog of the amino acid N-ace@ phenylalanine prepared by Matteson in 1981showedinhibitoryactivitycompared with chymotrypsin. Shenvi and Kettner recently prepared peptidy1 boronic acids that approach the TFMK series in their selectivity and potency in inhibiting HNE1*. The peptidic inhibitors contain an amino acid sequence based on that of synthetic substrates of HNE. Powers has led the field in producing very tight-binding, s&ctive squbstrates fo: HNE designed after the structure of the natural substrate, elastid3. Peptidic, irreversible inhibi~rs,~f HNE Peptidis irreversibie inhibitors include the peptidyl chloromethyl ketones (CMK)3, the amino acid sulfonate salts14 and the amino acid-derived latent isocyanates15. The CMK have been shown to
TlPS -August
1987 [Vol. 81
inhibit serine proteases by the initial formation of an E-I tetrahedral adduct between the inhibitor reactive carbonyl and the active site serine-OH followed by irreversible alkylation by the active site histidine16. A more detailed mc&&&ic st+&dj of the inhi_ biticn of HNE by methoxysuccinyl-Ala-Ala-Pro-Val-CMK was recently reported17, The sulfonates irreversibly inactivate HNE with concomitant release of bisulfite ion.
305
00 E-OH + RCONHR’
?E-O-$-R
7
7
E-OCOR
Heterocyclic, reversible inhibitors of HNE The isocoumarin, 3,4-dichloroisocoumarin2’ the substituted 2-pyronesz223’ modelled (structurally) after a natural HNE inhibitor, elasnin, and the benzoxazinones*4-27 are all mechanismbased reversible inhibitors of HNE. The 3,4-dichloroisocoumarins contain a masked acid chloride capable of acylating an active
--
+ NY,R’ --
E-OH.RCO,H
NHR’
t\! Ii E-OH + RC02H
(b)
2P
P, CF,
Heterocyclic, irreversible inhibitorsofHNE A new series of cephalosporins constitute a novel class of heterocyclic inhibitors of HNE (Table II). It has recently been demonstrated that certain cephalosporins having substituents in the 7ar position are potent inhibitors of HNE**. The sulphones are the most activ: members of the series and iI-. general, these compounds rapidly and irreversibly inactivate the enzyme. Preliminary kinetic data suggests a mechanism involving the formation of a reversible complex followed by acylation of an active site residue. Several other new classes of heterocyclic irreversible inhibitors of HNE have been reported4 including the isocoumarin 3alkoxy-7-amino-4-chloroisocouma&l9 and the ynenol lactoneszO. The compound 7-amino-4-chloroisocoumarin was designed to acylate the enzyme with the concomitant release of a quinone imine methide which could then irreversibly inactivate the enzyme by alkylation of an active site nucleophile. Many of the ynenol lactones have been shown to be substrates for HNE. However, ynenol lactones that are unsubstituted at the acetylene terminus are potent inhibitors of HNE.
E-OH.RCONHR’
+
E-Ser-OH
__
R
0-Ser-E /
R G
A
0
G(H)
cF?
(c) P,
PI S/OH
+
E-Ser-OH
RA
-_
_/O-Ser-E R
I OH
4 AH
OH
Fig. 1. (a) Typkzal reaction sequence Ibr serine protease (HNE) and inhibitor with formation of tetrahedraf adduct. (b) Fluorinated ketone inhibitor reacts with active site serine to form a stable hemiketaf adduct. (c) Formation of the tetrahedral covalent adduct of se&e active site with the boronic acid inhibitor.
site nucleophile. The inhibitory potency of the 2-pyrones is dependent on the nature and position of the alkyl chains on the ring and one of the more potent 2pyrones is shown in Table II. The mechanism of inhibition of HNE by the benzoxazinones has been recently reported27. UV spectral data for the interaction of HNE and benzoxazinone (B) Table II, suggests that an acyl-enzyme is formed initially which can then either undergo ring-closure to reform intact benzoxazinone or hydrolysis to liberate an Nacylanthranilic acid. Pharmacological profile The pharmacological profile of several of these new synthetic inhibitors of HNE in animal models of emphysema has been reported (see Ref. 28 for animal models of emphysema). Most of these models involve the induction of lung injury by the administration of an elastase [porcine pancreatic elastase (PPE) or HNE] intratracheally (i.t.) to hamsters with subsequent monitoring of the formation of either an acute hemorrhagic lesion (occurring in the first 24 hour period)s or an ‘emphysema-like’ lesion (occurring over a 2-4 week
period) in the absence and presence of inhibitor. The chloromethyl ketones (CMK) were the first class of compounds to be tested in animal models of emphysema3 and have proved effective in animal models when administered i.t., parenterally and orally. For example, hamsters injected (i.t.) with succinyl-AlaAla-Pro-Val-CMK 1 hour before administration of PPE (i.t.), did emphysema-like not develop lesions, whereas the converse procedure had no effect. However, the renal toxicity observed during these experiments rendered them unsafe for clinical use. The peptide boronic acids were administered i.t. concurrent with, or prior to, an i.t. or i.p. dose of PPE6, and any lesions were al:. lowed to progress over two weeks. Pdmonary alterations were assessed by measuring both physiologic parameters [total lung capacat 25 cm water pressure tgC25)] and morphometric parameters [mean linear intercepts in the elastin matrix of the lung (LM)]. An optimal 200 mg kg-l i.t. dose of methoxysuccinyl-Ala-AlaPro-boro-Val administered concurrently with PPE significantly inhibited (80%) the formation of the lung lesion as did 15 min post-
TIPS - August 1987 LVol. 81
306 TABLE
II. Hetsrocyclic
icing
Of
HLE Ref.
compoundand st~cturrt lmversible Cephalosporins
Icw = 5.0 x
1o-7(gmr’
)
18
19
Ynenol iactones
&=5x
104td
20
20
Reversible 0anzoxazinones
K-2.9x
loghn
24
K,=2.4x
1o-p~
27
PPymnes OH
K&,=2.68x
lodhn
23
0
b&l]
treatment with the inhibitor. A 15 min pretreatment with the inhibitor gave considerably less but still significant inhibition, An i.p. dose of the inhibitor
= 8920
21
(400 mg kg-‘) followed by an i.t. dose of WE resulted in about 30% inhibition. Gross observations of multiple organs showed no overt toxicity.
The peptide aldehyde inhibitors have been tested in a varie of animal models of emphysema 7 . The peptide portions of the aldehydes A and B (see Table I) were chosen sp~i~ca~y to maximize their overall lung retention time. These aldehydes have been tested in a model of lung injury based on hemorrhaging of the lung induced in hamsters by i.t. administration of purified HNE. The hemorrhage is quantitated by assay of the total hemoglobin content of the excised lungs. Hemorrhage was inhibited by 90% when a 10 pg per animal i.t. dose of A was given concomitantly with, or 40 minutes prior to, I-WE. Compound A was also tested in a prophylactic model of lung injury. A condition resembling emphysema is produced by repeated instillation of lower doses of HNE over several weeks. Compound A (200 l&gper animaij dosed it. concurrently with HNE significantly inhibited development of emphysema. A single i.p. dose of 3.2 g kg’-’ of B dosed to mice showed no overt toxicity. Compound C is a very potent, tight-binding reversible inhibitor of HNE; however its instability in viva made it unattractive as a potential clinical candidate for The degradation emphysema. products identified were attributed to initial oxidation of the valinal residue. The cephalosporins were tested for their ability to inhibit the formation of microvascular hemorrhage induced by an intradermal injection of soluble human PMN granule contents (which contains HNE activity} into rabbits. This hemorrhage is dependent on HNE activity and is quantitated by measuring the accumulation of 59Fe autologous red blood cells over 30 min at the injected skin sites. The cephalosporin shown in Table II completely inhibited the hemorrhagic response when dosed (100 Isg) concurrently with the PMN extractI*.
In 1983, it was generally accepted that the destruction of lung tissue observt?d in pulmonary emphysema was probably due to HNE. At that time, however, sufficiently selective, potent and metabolically stable synthetic
TPS - August 1987[Vol. S] HNE inhibitors did not exist to properly test the protease-antiprotease hypothesis in the clinic. Today, several new series of inhibitors have emerged, many of which appear to have the necessary profile to adequately test this hypothesis. However, their safety in both animals and humans must be assessed before clinical trials can begin. References 1 Janoff, A. (1985) Am. Rev. Respir. Dis. 132, 417-433 2 Snider, G. L., KIeinerman, J., Thurlbeck, W. M. and Bengali, Z. (1985) Am. Rev. Respir. Dis. 132, 182-185 3 Powers, J. C. (1983) Am. Rev. Respir. Dis. 127.554-558 4 Stein, R. L., Trainor, D.A. and Wildonger, R. A. (1985) Annu. Rep. Med. Ckem. 20,237-246 5 Fersht, A. (1977) Enzyme Structure and Mechanism, W. H. Freeman 6 Sostel, N. T., Watanabe, S., Hardie, R., Shenvi, A. B., Punt, J. A. and Kettner, C. (1986) Am. Rev. Respir. Dis. 133,635642 7 Bergeson, S., Schwartz. J. A., Stein, M. M., Wildonger, R. A., Edwards, A., Trainor, D.A., P. D., Shaw, Wolanin, D. J. (1986) European Patent Application EP 189305 A2 8 HassaI, C. H., Johnson, W. H.,
307 Kennedy,
A. J.
and
Roberts,
9 (1985) FEB.9 Mt. 183.201-205
N. A.
Dutta, A. S., Stein, R. L., Trainor, D. A. and Wildonger, R. A. (1986) US Patent 4, 596-789 10 Hori, H., Yasutake, A., Minematsu, Y. and Powers, J. C. (1985) in Peptides, Structure and Function (Proceedings of the Ninth American Peptide Symposium) (Deber, C. M., Hruby, V. J. and Kopple, K. D., eds), pp. 819-822, Pierce Chemi11 cal Company Stein, R. L., Strimpler, A. M., Trainor, D.A., Edwards, P. D., Lewis, J. L., Mauger, R. C., Schwartz, J. A., Stein, M. M., Wildonger, R. A. and Zottola, M. A. Biochemistry (in press) 12 Shenvi, A. 8. and Kettner, C. (19&Q) J. Biol. Chem. 259,15106-15114 13 Yasutake. A. and Powers, J. C. (1981) Biockemisty 20.3675-3679 14 Groutas, W. C., Brubaker, M. J., ZandIer, M. E, Stanga, M. A., Huang, T. L.. Castrisos. j. C. and Cmwlev, 1. P. (1985) Biockem. iiopkys. Res. Co&un. 128, go-93 15 Groutas, W. C., Abrams, W. R., Theodorakis, M. C., Kasper, A. M., Rude, S. A., Badger, R. C., Ocain, T. D., Miller, K. E., Moi, M. K., Brubaker, M. J., Davis, K. S. and ZandIer, M. E. (1985) j. Med. Ckem. 28,204-209 A. I., MacKenzie, N. E., 16 Scott, Malthouse, J. P. G., Primrose, W. V., Fagerness, P. E., Btisson, A., Qi, L. Z., Bode, W., Carter, C. M. and Jang, Y. J. (1986) Tetrahedron 42,326%3276 17 Stein, R. L. and Trainor, D.A. (1986) Biochemistry 25,5414-5419
18 Doherty, Ashe, I. B.. B. M., Argenbright, L. W., Barker, P. L., Bonney, Chandler, R. I.. G. O., DahIgren, M. E., Dom, C. P., Jr, Fit&e, P. E., Firestone, R. A., FletGer, D., W. K.,
Hagmann,
Mumford,
R,
O’Grady, L., Maycock, A. L., Pisano, J. M., Shah, S., K. Thompson, K. R. and Zimmerman, M. (1986) Nature 322,192194 19 Harper, J. W. and Powers, J. C. (1985) Biochemistry 24,720~7213 20 Copp, L. J., Krank, A. and Spencer, R. W. (1987) Biochemistry 26,169-178 21 Harper, J. W., Henuni, K. and Powers, J. C. (1985) Biochemistry 24,1831-l&41 22 Spencer, R. W., Copp, L. J. and PfIster, J. R. (1985) j. Med. Ckem. 28,182&1832 23 Groutas, W. C., Stanga, M. A., Brubaker, M. J., Huang, T. L., Moi, M. K. and CarroIL R. T. (19g5) j_ Xed. Ckem. 28,1106-1109 24 Teshima, T., Grifin, J. C. and Powers, J. C. (1982) J. Biol. Ckem. 257.5085-5091 25 Krantz, A., Tam, T. F. and Spencer, R. W. (1985) European Putent Application EP147.211 A2 26 Spencer, R W., L. J-, COPP, Bonaventura, B., Tam. T. F., Liak, T. J., Biiedeau, R. j. and Krantz, A. (1966) Biockem. Biopkys. Res. Commun. 140, 92g-933 27 Stein, R. L., Strimpler, A. M., ViscareIIo, 8. R.. Wildonger, R. A., Mauger, R. C. and Trainor, D.A. Biockemistre_ (in
press)
28 Snider, G. L., Lucey, R. C. and Stone, P. J. (1986) Am. Rev. Respir. Dis. 133, 149-169
NEUROCHEMlCALS FOR THE NEUROSCIENTIST NEW PF?QDUCTS Solectlve Dopamlno &denohwReceptor Li9ands
Rooeptor Lieande 3-PPP, R(+) and S!.! isomers R-AHPIA BCyclopentvl-1,3.dioropylxanthine (*)_PPHT B-Cyclopentyl-1,9dimethylxanthine SKF-39393, (*I. R(+) and S+) isomers 5”(N-cyclopropyI)_carboxamidoExcltetory Amino Aold adenosine (i)+Aminophosphonobutyric 2-Phenylaminoadenosina (CV-1808) (,+Cpp Xanthine Amine Congener (XAC) GA9Aor@~e Cholineetereae Inhibitors SR-95531 9=Amino-l&3,4-letrhydroacridine THIP (_)_Eseroline Serotonergio Llgands Oxotremorine M (a)_DOI Dlacylglycsrol Klnase lnhlbltor 1c8205930 R-59022 MDL-72222 For further information aboul these or other related products acling at the adenosine, adrenergic. benzodiazepine. dopaminergic, opioid, GABA. serotonin and cholinergic receptors or pteridines. uric acids and melhylxanlhines. please write for our calalogue.
I
Research Blochemloals Incorpotated 9 Erlr Orlve, Natlck. MA01760-1390 U.S.A. (6t’f) 851.1111. is!ax 516 501 srez;t?t9 et0 let?) DISTRIBUTORS
UK: tbmrt Twhnlul brmany, Swlk4rknd, I4pm:
Funakorhl
Ltd., 1 Ex4outlvo Pad& St. Albw& Hwk AU 4TA UK (0727) 4lM4 Auatrll: ANAWATmdlnS SA, UnkrclOrktr. 23. CH-SW2 WanS#n Swlk4rknd. (01) 139 02 SO Phwmw%utlul Co.. Ltd., 2.3 Sumgadal Kmdr, Chkodr-ku, Tokyo Jrnpm (02) 292.2562
Brandel Receptor Binders,tried and tested throughout the Wotid, now have an automatic option - the new Brandel AUTOMARC DEPOSm AND DlSPENSlNG (ADD) SysteIII MJOR Receptor BIader 0 Comoatible with ADD System.
I
0 Harvests 30 wells simultaneouslyin 30 seconds. l Filter dws perforated from low cost filter strips during harvesting. 0 Aspirates from almost any sue test 0 Ready for use. Complete with all tubw vials filter papers etc. 0 Depasjts all 30 filtn disu at one bme into 20ml scantillabonuals. 3 A~$ema!!c and equal delwy of scantil!a tion fluid to vial% 0 Volume regulator. l Alter paper and deposit system keyed tc prevent mw up. Full details from the Europe-anDistnbutor E$$C horn ~mspc(ive Evmpw rS--
Circle no. 72 on advertising enquiry form Circle no. 138on advertising enquiry term