Quantitative Evaluation of Retroviral Gene Transduction Efficiency in Human Lung Cancer Cells

Abstract

Gene therapy may serve as a valuable therapeutic modality for malignancies, such as lung cancer, that are poorly responsive to conventional therapies. Although many methods for transducing new genes into cells have been described, little is known about gene transduction into lung cancer, especially under conditions that might be encountered in clinical use. As a first step in addressing this important issue, the study presented here examined the ability of a recombinant retrovirus to add a selectable marker gene to the A549 non-small cell lung cancer (NSCLC) cell line under a variety of conditions. Examination of viral exposure times ranging from 30 sec to 4 hr revealed that the number of infected cells increased with every increment in time. By increasing the multiplicity of infection to 1.0 and including a polycation, Polybrene, as an infection facilitator, 0.8% of the NSCLC cells were infected with only a 30-sec viral exposure. Nebulization, a potentially attractive route of administration for pulmonary malignancies, had no significant effect on viral titer, proviral structure, or proviral transcripts. A single lyophilization did reduce viral titer by 58 ± 6%, but did not affect the proviral structure or transcripts produced by the surviving viruses. These results suggest that recombinant retroviruses have the potential to add new genes to malignancies accessible by the airways under conditions likely required for clinical use.

Overview summary

Future human gene therapy strategies for solid tumors, such as lung cancer, will likely employ in vivo gene transduction. Using a human lung cancer cell line, Rousculp et al. show that low retroviral gene transduction efficiency at short viral exposure times can be partially overcome by increasing the multiplicity of infection. They also demonstrate that nebulization had no significant effects on viral titer, or on proviral structure and function. These experiments demonstrate that significant numbers of malignant cells can be transduced with functional recombinant retrovirus under some conditions associated with in vivo delivery.