HYNIC and DOMA conjugated radiolabeled bombesin analogs as receptor-targeted probes for scintigraphic detection of breast tumor

Abstract

Background Among the many peptide receptor systems, gastrin-releasing-peptide (GRP) receptors, the mammalian equivalent of bombesin (BN) receptors, are potential targets for diagnosis and therapy of breast tumors due to their overexpression in various frequently occurring human cancers. The aim of this study was to synthesize and comparative evaluation of 99m Tc-labeled new BN peptide analogs. Four new BN analogs, HYNIC-Asp[PheNle]BN(7-14)NH 2 , BN1; HYNIC-Pro-Asp[TyrMet]BN(7-14)NH 2 , BN2; HYNIC-Asp-Asn[Lys-CHAla-Nle]BN(7-14)NH 2 , BN3; and DOMA-GABA[Pro-Tyr-Nle]BN(7-14)NH 2 , BN4 were synthesized and biologically evaluated for targeted imaging of GRP receptor-positive breast-tumors. Methods Solid-phase synthesis using Fmoc-chemistry was adopted for the synthesis of peptides. BN1–BN4 analogs were better over the standard Gln-Trp-Ala-Val-Gly-His-Leu-Met-NH 2 (BNS). Lipophilicity, serum stability, internalization, and binding affinity studies were carried out using 99m Tc-labeled analogs. Biodistribution and imaging analyses were performed on MDA-MB-231 cell-induced tumor-bearing mice. BN-analogs induced angiogenesis; tumor formation and GRP-receptor-expression were confirmed by histology and immunohistochemistry analyses of tumor sections and important tissue sections. Results All the analogs displayed ≥ 97% purity after the HPLC purification. BN-peptide-conjugates exhibited high serum stability and significant binding affinity to GRP-positive tumor; rapid internalization/externalization in/from MDA-MB-231 cells were noticed for the BN analogs. BN4 and BN3 exhibited higher binding affinity, stability than BN1 and BN2. Highly specific in vivo uptakes to the tumor were clearly visualized by scintigraphy; rapid excretion from non-target tissues via kidneys suggests a higher tumor-to-background ratio. BN4, among all the analogs, stimulates the expression of angiogenic markers to a maximum. Conclusion Considering its most improved pharmacological characteristics, BN4 is thus considered as most promising probes for early non-invasive diagnosis of GRP receptor-positive breast tumors. Electronic supplementary material The online version of this article (10.1186/s13550-019-0493-x) contains supplementary material, which is available to authorized users.

Preclinical Advances in Theranostics for the Different Molecular Subtypes of Breast Cancer

“…GRPR is reported to be overexpressed in 96% of breast cancer tissues across all molecular subtypes of breast cancer. The GRPR-targeted agents for both imaging and therapy achieved excellent tumor uptake, such as 111 In-JMV4168 for luminal-subtype imaging ( Dalm et al, 2015 ), 68 Ga-NOTA-PEG 3 -RM26 for HER2-subtype imaging ( Varasteh et al, 2014 ), 99m Tc-BN4 for TNBC imaging ( De et al, 2019 ), 177 Lu-DOTA-DN(PTX)-BN for luminal-subtype therapy ( Gibbens-Bandala et al, 2019a ), and 177 Lu-BN-PLGA (PTX) for TNBC therapy ( Gibbens-Bandala et al, 2019b ). These independent studies indicate that GRPR is a highly promising target for theranostics of breast cancer.…”

Decapeptide Modified Doxorubicin Loaded Solid Lipid Nanoparticles as Targeted Drug Delivery System against Prostate Cancer

“…6-Hydrazinopyridine-3-carboxylic acid (HYNIC) was prepared prior to the synthesis of the LHRH decapeptide following the earlier reports. , following is the amino acid sequence in the new LHRH peptide analog: d -Glu 1 -His 2 -Trp 3 -Ser 4 - d -Tyr 5 - d -Asn 6 -Leu 7 - d -Gln 8 -Pro 9 -Gly 10 -NH 2 (here after termed as NLH). Pyro-glutamine in position 1 was substituted by d -glutamine ( d -Glu), glycine in position 6 was substituted by d -aspergine ( d -Asn) and arginine in position 8 was substituted by d -glutamine of the native LHRH (sequence: p Glu 1 -His 2 -Trp 3 -Ser 4 -Tyr 5 -Gly 6 -Leu 7 -Arg 8 -Pro 9 -Gly 10 -NH 2 ) New decapeptide analogue was synthesized by using Rink amide MBHA resin; the amino acids were protected by fluoenylmethodxy carbonyl (Fmoc).…”

“…6-Hydrazino-3-carobylic acid (HYNIC) has significant impacts on LHRH hydrophilicty, receptor affinity, tumor targeting, and urinary clearance that play important roles in cancer diagnosis. , Hence the theranostic potential of DOX-loaded HYNIC conjugated LHRH peptide decorated SLN are considered to be significantly important in terms of DOX-induced chemotherapy. , Toward this endeavor, dipalmitoylphosphatidylethanolamine (DPPE) was conjugated with polyethylene glycol (PEG, to impart stealth nature in the SLN); subsequently it was conjugated with the aforementioned new LHRH analog, henceforth known as DPPE-PEG-HYNIC-NLH. Superiority of surface modified DOX-loaded SLN (M-DSLN) was compared with DOX-loaded SLN (DSLN).…”

Study of the 99mTc‐labeling conditions of 6‐hydrazinonicotinamide‐conjugated peptides from a new perspective: Introduction to the term radio‐stoichiometry

“…67,68 Table 3 summarizes the radio-stoichiometric relationships of HYNIC-conjugated bombesin analog peptides. 25,60,[69][70][71][72][73][74][75][76]…”

“…Therefore, this analog is considered a proper candidate for the identification of bombesin‐positive tumors 67,68 . Table 3 summarizes the radio‐stoichiometric relationships of HYNIC‐conjugated bombesin analog peptides 25,60,69–76 …”