Urologic applications of gene therapy

Exploiting the Intron-splicing Mechanism of Insect Cells to Produce Viral Vectors Harboring Toxic Genes for Suicide Gene Therapy

Two mammalian introns, the human growth hormone intron and the Simian virus 40 large T antigen intron, were inserted into the coding sequences of diphtheria toxin fragment A (DT-A) and barnase (Bar), respectively, to disrupt their open-reading frames (ORFs). Expression of these two toxic proteins were totally abolished, which enabled the production of normal levels of recombinant baculoviral and adeno-associated viral (AAV) vectors in insect cells. When these viral vectors were introduced into mammalian cells, the introns were spliced out and the toxic proteins were expressed, which resulted in apoptosis in mammalian cells. This is the first report to show that viral vectors harboring toxin genes can be produced at normal levels by exploiting the intron-splicing mechanism of insect cells. Furthermore, viral vectors carrying the DT-A gene under control of tumor-specific promoters were able to exert tumor-specific cell killing. This novel method to produce viral vectors harboring toxic genes under control of tumor-specific promoter offers a powerful tool for further research, as well as for the development of toxin-based suicide gene therapy drugs.Molecular Therapy - Nucleic Acids (2012) 1, e57; doi:10.1038/mtna.2012.48; published online 27 November 2012.

Prostate cancer gene therapy

Cancer-specific gene therapy is still in its infancy. Although the first gene therapy trials were initiated in the late 1980s, it was only more recently that the first successful treatment of a genetic disease was reported.3 The current problems with low efficiency of gene transfer coupled with the immunologic difficulties with certain vectors indicate that more effort needs to be directed at the basic science of gene transfer. Ultimately, successful cancer-specific gene therapy will require combinations of the lessons learned from the ex vivo and in vivo paradigms. The next generation of gene therapy trials likely will focus on combination therapy with conventional chemotherapeutic agents, differentiating agents, or radiation therapy. The obstacles to the development of gene-based human therapeutics (i.e., molecular medicine) are formidable, but the benefits are so great that eventually the technical issues of gene transfer methodology will be worked out, and ultimately this will become the standard of care, not only for inborn errors of metabolism, but also for cancer.

Immediate vs. delayed androgen deprivation for prostate cancer

Androgen ablation has been the standard treatment of symptomatic patients with metastatic prostate cancer for more than 50 years. Within the last 15 years, the introduction of prostate-specific antigen (PSA) has induced a stage migration toward less extensive disease and a dramatic decrease in the proportion of men presenting with N+/M+ disease. Historical studies, conducted during the pre-PSA era, are therefore of limited interest in counseling modern patients. The routine use of radical therapies such as radical prostatectomy and radiotherapy has considerably expanded the problem of timing of endocrine treatment in range and complexity. Advanced disease is now diagnosed in patients with limited involvement of extraprostatic sites and even in patients presenting an isolated elevation of PSA after radical treatment. In the absence of clear guidelines, data from past literature and ongoing modern studies were compiled in the present review in an attempt to generate practical considerations.

Molecular-based therapies for renal cell carcinoma

The incidence of renal cell carcinoma (RCC) is rising steadily, but the ability to cure patients with metastatic RCC unfortunately remains limited. Emerging interest in gene therapy performance and safety is expressed by patients, medical institutes, and other agencies. It has become evident that better understanding of the genetic impairments and immune pathophysiology in RCC is essential for future improvement in patient care. Clinical trials now underway that are focusing on genetic and immune impairments will hopefully lead to future breakthroughs in RCC therapy. This paper reviews available gene therapies and other related therapeutic approaches for RCC and lists some of the current clinical trials focused on molecular-based therapies.