The role of herpes simplex virus thymidine kinase in the treatment of solid tumours

Molecular imaging: a primer for interventionalists and imagers

The characterization of human diseases by their underlying molecular and genomic aberrations has been the hallmark of molecular medicine. From this, molecular imaging has emerged as a potentially revolutionary discipline that aims to visually characterize normal and pathologic processes at the cellular and molecular levels within the milieu of living organisms. Molecular imaging holds promise to provide earlier and more precise disease diagnosis, improved disease characterization, and timely assessment of therapeutic response. This primer is intended to provide a broad overview of molecular imaging with specific focus on future clinical applications relevant to interventional radiology.

Molecular Imaging: A Primer for Interventionalists and Imagers

The characterization of human diseases by their underlying molecular and genomic aberrations has been the hallmark of molecular medicine. From this, molecular imaging has emerged as a potentially revolutionary discipline that aims to visually characterize normal and pathologic processes at the cellular and molecular levels within the milieu of living organisms. Molecular imaging holds promise to provide earlier and more precise disease diagnosis, improved disease characterization, and timely assessment of therapeutic response. This primer is intended to provide a broad overview of molecular imaging with specific focus on future clinical applications relevant to interventional radiology.

Construction of HSV-tk/GCV suicide gene system for hepatocarcinoma cells and its bystander effect in rats

AIM: To construct the therapeutic system of HSV-tk/GCV suicide gene for hepatocarcinoma cell line, and to establish a cell model and method to examine the effect of HSV-tk/GCV system and its bystander effect.

METHODS: CBRH7919 cells was infected by the active retrovirus particle excreted by the packaging cell line PT67/tk, and then a high anti-G418 clone named CBRH7919/tk was obtained by G418 screening for 3 wk. The total DNAs of CBRH7919 and CBRH7919/tk cells were extracted. The cDNA fragments of HSV-tk were labeled with Digoxin and then hybridized with the DNAs of CBRH7919, CBRH7919/tk cells and positive controls. The CBRH7919 and CBRH7919/tk cells were treated with different concentrations (0.1, 1, 10, 50, and 100 mg/L) of GCV, respectively. The mixture with different ratios of tk positive and negative cells was also treated with GCV. The survival rates of the cells were examined by MTT assay. The bystander effect was analyzed to determine a suitable proportion of tk positive cells for the successive experiments.

RESULTS: A high anti-G418 clone named CBRH7919/tk (tk⁺) was obtained. The HSV-tk gene was detected in the CBRH7919/tk cells, while it was not detected in the CBRH7919 cells. GCV showed significant cytoxicity and inhibition on the proliferation of CBRH7919/tk cells in a concentration- and time-dependent manner. The CBRH7919(tk^-) cells manifested low sensitivity to GCV. The killing rate of GCV to the mixtures containing 5% and 10% tk positive cells were 6.0% and 25.2%, respectively. The sensitivity of MTT assay in the detection of the bystander effect was relatively high, and the bystander effect was low when the mixture contained 5-10% tk positive cells.

CONCLUSION: The therapeutic system of HSV tk/GCV suicide gene for hepatocarcinoma cells in rats is successfully constructed, and the mixed cells containing 5-10% tk positive ones can be used for further study.

Potential applications of gene therapy in the patient with cancer

The elderly population has much to gain from the advances of molecular medicine, although at present genetic pharmacology remains mostly at the conceptual level. Cancer, in particular, is an increasing health burden and the majority (over 70%) of gene therapy trials are aimed at tackling this problem. Available strategies employ both viral and synthetic vectors with the selective delivery and expression of therapeutic genes a pivotal requirement. Clinical trials are now in progress with a view to modulating disease at many different levels, including the direct replacement of abnormal genes. suicide-gene formulations, and the delivery of 'gain of function' genes, which seek to alter the malignant phenotype by indirect means, such as, immunopotentiation and stromal reorganisation. Early data from these studies is tantalising and we must remain optimistic that gene therapy will benefit the patient with cancer by both reducing morbidity and extending life.