Biomedical subjects

M R Aruva

Publications and source records attributed to M R Aruva.

6 recordsLinked to original sources

PubMed2007

Receptor-mediated internalization of chelator-PNA-peptide hybridization probes for radioimaging or magnetic resonance imaging of oncogene mRNAs in tumours.

Early external detection of cancer gene activity might enable early treatment of cancer and might reduce cancer mortality. We hypothesized that oncogene mRNA overexpressed at thousands of copies per malignant cell in a zone of transformed cells could be imaged externally by scintigraphic imaging, PET (positron emission tomography) or MRI (magnetic resonance imaging) with PNA (peptide nucleic acid) hybridization probes that include chelators for metal cations and a cyclized peptide analogue of IGF-1 (insulin-like growth factor 1), D(Cys-Ser-Lys-Cys), to mediate internalization by IGF1R (IGF-1 receptor) overexpressed on cancer cells. We observed that human MCF7 breast cancer cells that overexpress IGF1R efficiently internalized fluorescein-chelator-PNA-D(Cys-Ser-Lys-Cys) to the cytoplasm, but not with D(Cys-Ala-Ala-Cys). Scintigraphic imaging of MCF7 xenografts in immunocompromised mice revealed that CCND1 and MYC [(99m)Tc]chelator-PNA-D(Cys-Ser-Lys-Cys) probes yielded xenograft. PET imaging with [(64)Cu]chelator-PNA-D(Cys-Ser-Lys-Cys) yielded stronger signals. Scintigraphic imaging of human AsPC1 pancreas cancer xenografts with [(99m)Tc]chelator-KRAS PNA-D(Cys-Ser-Lys-Cys) yielded strong xenograft signals. Stronger xenograft image intensities were obtained by PET imaging of [(64)Cu]chelator-KRAS PNA-D(Cys-Ser-Lys-Cys). MRI required extension of chelator-polydiamidopropanoate dendrimers from the N-termini of the PNA probes to increase the number of contrast paramagnetic gadolinium (III) cations per probe. These results provide a basis for detection of oncogene activity in tissues from outside the body by hybridization with metal-chelator-PNA-peptides that are selectively internalized by cancer cells.

Animals↗

PubMed2006

99mTc-Fanolesomab: affinity, pharmacokinetics and preliminary evaluation.

Localization of infection is critical for both diagnosis and treatment. Several radioactive compounds such as (67)Gallium citrate, (111I)ndium and (99m)Technetium-labeled leukocytes, peptides and antibodies have been used to localize sites of bacterial infection and phlegmons when anatomical imaging techniques failed. With labeled leukocytes the major concern besides the cost, was the in vitro procedure requiring more than 2 h and trained personnel to handle blood samples. Such limitations paved the way for the emergence of new agents like human immunoglobulin, interleukin-1, peptides and monoclonal antibodies. Following the intensive study of 10 monoclonal antibodies the anti SSEA-1 antibody specific for CD15 antigen was found to have a high Kd value of 1.6x10(-11) M for human neutrophils. Labeling of anti CD15 antibody (NeutroSpec) with (99m)Tc and its FDA approval was a boon to diagnostic imaging as it promised to eliminate many of the well known drawbacks of the in vitro WBC labeling. This antibody has a large number of antigenic binding sites: 5.1x10(5) per circulating human neutrophil. It has been established that very little CD15 antigen is expressed on the other blood cell lines. Upon intravenous administration to patients there was no adverse reaction except in those with underlying cardiovascular compromise or chronic pulmonary obstructive disease. Another advantage is that, this particular monoclonal antibody has not produced significant human antimouse antibody in research volunteers and patients. Twenty-four hour imaging, SPECT or planar was not required. The following pages describe the various stages of the research activity carried out towards NeutroSpec.

Animals↗

PubMed2006

Stem cells: a regenerative pharmaceutical.

Stem cells (SC), found in both adult and fetal tissues, are self-renewing elements that can generate the various cell types in the body. There are 3 classes of SC: totipotent, multipotent, and pluripotent. The SC with a significant developmental potential are the embryonic stem (ES) cells, which are derived from the early stages of mammalian embryo. SC possess regenerative properties and this offers unprecedented opportunities for developing medical therapies for debilitating diseases. Hematopoietic SC have been used successfully in bone marrow transplants for over 40 years. Pluripotent SC offer renewable source of replacement of cells and tissues to treat a myriad of diseases. However there are limiting factors. Adult SC are rare and cannot multiply as the ES. Pluripotent SC have great therapeutic potential, but face technical challenges. A serious concern is the ethical issue since they are derived from human embryos or fetal tissue. Quite often SC have been targets of mutations and risk carcinogenesis. Various markers have been identified based on the uniqueness of SC receptors and in vivo tracking studies using nanocolloids and radioactive tracers have been performed. Though 111In-oxine has been used to image SC transplants, PET with a high spatial resolution would be ideal. Currently 2 agents are being studied, 18F-FDG and 64Cu-Pyruvaldehyde bi(N4-methylthiosemicarbazone). The following few pages bring forth the various limitations and summarize progress made in SC utilization so as to create awareness of SC research in ISORBE community and to foster strategy that ISORBE community can disseminate information and exchange knowledge on radio labeled SC.

Humans↗

PubMed2005

Tumor-targeting peptide-PNA-peptide chimeras for imaging overexpressed oncogene mRNAs.

We have optimized a method involving continuous solid phase synthesis of chelator-peptide-PNA-peptide probes in order to noninvasively image oncogene mRNAs overexpressed in tumors. The PNA (peptide nucleic acid) probes carry cyclized peptide ligand analogs specific for receptors overexpressed on malignant breast or colorectal cancer cells, and chelators to bind radioactive metal ions, or a fluorophore. In vivo scintigraphic imaging of MCF7 xenografts in immunocompromised mice indicated that CCND1 and MYC [99sTc] chelator-PNA-D (CSKC) probes concentrated in MCF7 cells up to 7 times more than the corresponding mismatch controls.

Breast Neoplasms↗

PubMed2005

Synthesis of novel peptide nucleic acid-peptide chimera for non-invasive imaging of cancer.

A chelator-peptide-PNA-peptide chimera specific for KRAS has been prepared by continuous solid phase coupling with a C-terminal insulin-like growth factor 1 (IGF1) ligand, D(cys-ser-lys-cys), and N-terminal bis(S-benzoyl thioglycoloyl) diaminopropanoate chelator for radionuclide labeling. The probe was purified by RP-HPLC and characterized by MALDI-TOF mass spectroscopy. The probe was labeled with 99mTc and 64Cu. Both labeled probes accumulated in human pancreatic cancer xenografts in immunocompromised mice. Control experiments with mismatch chimeras and control xenografts will be necessary to determine the specificity of this molecular diagnostic strategy.

Animals↗

PubMed2003

99mTc-peptide-peptide nucleic acid probes for imaging oncogene mRNAs in tumours.

Imaging oncogene mRNA in tumours would provide a powerful tool for the early detection of occult malignant lesions. The goal was to prepare a chimera consisting of a dodecamer antisense peptide nucleic acid (PNA) specific for c-MYC oncogene overexpressed in human breast cancer cells and a chelating moiety that facilitates quantitative radiolabelling with 99mTc and evaluate it for hybridization and tissue distribution in laboratory animals. The pentapeptide chelator-PNA dodecamer specific for c-MYC mRNA was extended from a solid support by 9-fluorenylmethyloxycarbonyl (Fmoc) coupling. Similarly, a chelator-PNA chimera with four central mismatches was also prepared which served as a control. The chimeras were purified, characterized and evaluated for hybridization to c-MYC mRNA by fluorescent, real-time polymerase chain reaction (RT-PCR). The chimeras were labelled with 99mTc and their tissue distribution was examined in athymic nude mice bearing experimental human breast tumours. 99mTc radiolabelling was quantitative and presented a single peak in reversed phase liquid chromatography. Fluorescent real-time polymerase chain reactions using primer and fluorescent probe sets previously calculated for c-MYC mRNA demonstrated inhibition of reverse transcription by the c-MYC specific chimera as compared to that of the control. Tissue distribution studies of antisense and mismatch chimeras at 4 h and 24 h after administration displayed modest accumulation in the liver, and appreciable levels in tumours. These observations suggest that 99mTc-peptide-PNA probes might be useful for imaging gene expression in tumours, and the approach is worthy of further investigation.

Animals↗