Aim. The alpha(v)beta(3) integrin is a cell adhesion receptor involved in angiogenesis, tumor cell migration and metastatic dissemination. The tripeptide sequence RGD binds to alpha(v)beta(3) but also interacts with other integrins. We developed a novel cyclized RGD pentapeptide covalently linked by a spacer to an echistatin domain that showed a high selectivity for alpha(v)beta(3) integrin ( J Med Chem 2006, 49:3416-3420). Materials and Methods. In the present study we evaluated this chimeric RGD peptide (RGDechi) in human erythroleukemia K562 cells, stably cotransfected with cDNA of alpha(v) or alpha(IIb) and beta(3) or beta(5) subunits by adhesion assays, competitive binding assays and cross-linking experiments. RGDechi was then conjugated with DTPA and labeled with 111In for SPECT imaging whereas a one-step procedure was used for labeling the chimeric peptide with 18F for PET imaging. K562 cells overexpressing alpha(v)beta(3) or alpha(v)beta(5) were subcutaneously injected into opposite flanks of individual nude mice and allowed to grow up to 0.5 cm in size. Alternatively, U87MG human glioblastoma cells and A431 human epidermoid cells endogeneously expressing high levels of alpha(v)beta(3) and alpha(v)beta(5), respectively, were used to develop xenografts in nude mice. Imaging studies were then performed using both SPECT and microPET. Results. Adhesion assays showed that the chimeric RGDechi was able to inhibit adhesion of alpha(v)beta(3) overexpressing cells but not alpha(IIb)beta(3) and alpha(v)beta(5) overexpressing clones to native ligands. Nude mice bearing K562 and U87MG tumor xenografts, both overexpressing alpha(v)beta(3), showed a high tumor uptake of 111In-labeled and 18F-labeled RGDechi assessed by SPECT and microPET, respectively. No tumor uptake of radiolabeled RGDechi could be observed in K562 and A431 tumor xenografts overexpressing alpha(v)beta(5). Conclusion. Our findings indicate that chimeric RGDechi is suitable for in vivo selective alpha(v)beta(3) receptor imaging.
In vivo imaging of alpha(v) beta(3) integrin expression with a radiolabeled chimeric RGD peptide / DEL VECCHIO, Silvana; Zannetti, A; Panico, Mr; Speranza, A; Iommelli, F; Papaccioli, A; Sommella, J; Lettieri, A; Saviano, M; Zaccaro, L; Del Gatto, A; Lang, L; Pedone, C; Salvatore, M.. - In: EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING. - ISSN 1619-7070. - STAMPA. - 34 (Suppl.2):(2007), pp. S200-S200.
In vivo imaging of alpha(v) beta(3) integrin expression with a radiolabeled chimeric RGD peptide
DEL VECCHIO, SILVANA;
2007
Abstract
Aim. The alpha(v)beta(3) integrin is a cell adhesion receptor involved in angiogenesis, tumor cell migration and metastatic dissemination. The tripeptide sequence RGD binds to alpha(v)beta(3) but also interacts with other integrins. We developed a novel cyclized RGD pentapeptide covalently linked by a spacer to an echistatin domain that showed a high selectivity for alpha(v)beta(3) integrin ( J Med Chem 2006, 49:3416-3420). Materials and Methods. In the present study we evaluated this chimeric RGD peptide (RGDechi) in human erythroleukemia K562 cells, stably cotransfected with cDNA of alpha(v) or alpha(IIb) and beta(3) or beta(5) subunits by adhesion assays, competitive binding assays and cross-linking experiments. RGDechi was then conjugated with DTPA and labeled with 111In for SPECT imaging whereas a one-step procedure was used for labeling the chimeric peptide with 18F for PET imaging. K562 cells overexpressing alpha(v)beta(3) or alpha(v)beta(5) were subcutaneously injected into opposite flanks of individual nude mice and allowed to grow up to 0.5 cm in size. Alternatively, U87MG human glioblastoma cells and A431 human epidermoid cells endogeneously expressing high levels of alpha(v)beta(3) and alpha(v)beta(5), respectively, were used to develop xenografts in nude mice. Imaging studies were then performed using both SPECT and microPET. Results. Adhesion assays showed that the chimeric RGDechi was able to inhibit adhesion of alpha(v)beta(3) overexpressing cells but not alpha(IIb)beta(3) and alpha(v)beta(5) overexpressing clones to native ligands. Nude mice bearing K562 and U87MG tumor xenografts, both overexpressing alpha(v)beta(3), showed a high tumor uptake of 111In-labeled and 18F-labeled RGDechi assessed by SPECT and microPET, respectively. No tumor uptake of radiolabeled RGDechi could be observed in K562 and A431 tumor xenografts overexpressing alpha(v)beta(5). Conclusion. Our findings indicate that chimeric RGDechi is suitable for in vivo selective alpha(v)beta(3) receptor imaging.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
