Radiolabeled PNAs for imaging gene expression

Abstract

Scintigraphic imaging of gene expression in vivo by non-invasive means could precisely direct physicians to appropriate intervention at the onset of disease and could contribute extensively to the management of patients. However, no method is currently available to image specific overexpressed oncogene mRNAs in vivo by scintigraphic imaging. Nevertheless, we have observed that Tc-99m-peptides can delineate tumors, and that PNA-peptides are specific for receptors on malignant cells and are taken up specifically and concentrated in nuclei. We hypothesize that antisense Tc-99m-PNA-peptides will be taken up by human breast cancer cells, hybridize to complementary mRNA targets, and permit imaging of oncogene mRNAs in human breast cancer xenografts in a mouse model, providing a proof-of-principle for non-invasive detection of precancerous and invasive breast cancer. Oncogenes cyclin D1, erbB-2, c-MYC, and tumor suppressor p53 will be probed. If successful, this technique will be useful for diagnostic imaging of other solid tumors as well.<br>Imagens cintigráficas da expressão genética in vivo por metódos não invasivos poderiam orientar mais precisamente as intervenções médicas para o local definido da doença e poderia contribuir para melhor tratamento dos pacientes. Entretanto, nenhum método está atualmente disponível para a imagem específica da intensa expressão de um oncogene de RNAm (s) in vivo por imagem cintigráfica. Contudo, nós temos observado que peptídeos marcados Tc-99m podem delinear tumores, e que peptídeos PNA são específicos para receptores em células malignas e são captados e concentrados no núcleo. Nós sugerimos que peptideos PNA nonsense marcados com Tc-99m serão capturados pelas células neoplásicas de mama humana, hibridizarão com sequências complementares de alvos de RNAm e permitirão imagen de oncogenes de RNAm em câncer de mama humana com enxerto em modelo animal, provendo um prova do princípio de detecção câncer de mama em estado pré-cancer e não invasivo. Oncogenes ciclin D1, erb B-2, c-MYC, e um tumor supressor p53 irão ser explorados. Se obtivermos sucesso, está técnica também irá ser útil no diagnóstico de imagens de outros tumores sólidos

Preparation, 99mTc-labeling and biodistribution studies of a PNA oligomer containing a new ligand derivative of 2,2′-dipicolylamine

“…In such constructs, the role of the PNA is to direct the bioconjugate to a specific mRNA -a unique or a uniquely over-expressed mRNA in a diseased cell -while the function of the radioactive probe is to allow imaging to possibly provide information on cellular gene expression pattern and detect molecular changes at relatively early stages [13,42]. Hence, a number of in vivo biodistribution/hybridization studies of radiolabeled PNAs were undertaken [14,[17][18][19][20]22,[24][25][26][27][28][29][30][31][32][33]36,39,41,[43][44][45][46]. The majority of these reports involved the use of 99m Tc, probably due its ideal nuclear properties and the convenient availability from a commercial generator [47][48][49][50].…”

Towards the Preparation of Novel Re/99mTc Tricarbonyl-Containing Peptide Nucleic Acid Bioconjugates

“…19,31,[40][41][42][43][44] For the purpose of this work, we decided to use a di-(2-picolyl)amide (Dpam) derivative (3, Figure 1) as a coordination entity for Re/ 99m…”