RNA interference as a key to knockdown overexpressed cyclooxygenase-2 gene in tumour cells

Abstract

Silencing those genes that are overexpressed in cancer and contribute to the survival and progression of tumour cells is the aim of several researches. Cyclooxygenase-2 (COX-2) is one of the most intensively studied genes since it is overexpressed in most tumours, mainly in colon cancer. The use of specific COX-2 inhibitors to treat colon cancer has generated great enthusiasm. Yet, the side effects of some inhibitors emerging during long-term treatment have caused much concern. Genes silencing by RNA interference (RNAi) has led to new directions in the field of experimental oncology. In this study, we detected sequences directed against COX-2 mRNA, that potently downregulate COX-2 gene expression and inhibit phorbol 12-myristate 13-acetate-induced angiogenesis in vitro in a specific, nontoxic manner. Moreover, we found that the insertion of a specific cassette carrying anti-COX-2 short hairpin RNA sequence into a viral vector (pSUPER.retro) greatly increased silencing potency in a colon cancer cell line (HT29) without activating any interferon response. Phenotypically, COX-2 deficient HT29 cells showed a significant impairment of their in vitro malignant behaviour. Thus, the retroviral approach enhancing COX-2 knockdown, mediated by RNAi, proved to be an useful tool to better understand the role of COX-2 in colon cancer. Furthermore, the higher infection efficiency we observed in tumour cells, if compared to normal endothelial cells, may disclose the possibility to specifically treat tumour cells without impairing endothelial COX-2 activity.

Targeting of COX-2 Expression by Recombinant Adenovirus shRNA Attenuates the Malignant Biological Behavior of Breast Cancer Cells

“…The advancement in the field of RNA interference (RNAi) has opened up a new strategy to target silence genes involved in tumour progression which may avoid these side effects (Charames et al, 2006;Strillaeeit et al, 2006). Besides the selection of target gene, the choice of carrier is equally important for cancer gene therapy, and efficient gene delivery system is the basis of gene therapy.…”

Proof concept for clinical justification of network mapping for personalized cancer therapeutics

“…A combination of shRNA vectors targeting multiple cancer support pathways and multifunctional RNAi constructs are expected to optimize therapeutic potential. 78,79 The time required to determine high-probability protein targets (3-6 weeks) and to manufacture and validate safety of an shRNA product (6 months) may limit the use of this technology in patients with rapidly progressive disease, but conservation of the priority protein targets in tumor samples as demonstrated from patient RW001 with samples harvested nearly 10 months apart suggest an opportunity for application in patients with earlier stage, slowly progressive disease or recurrent disease following a long-latent period.…”

Improved anti-tumor therapy based upon infectivity-enhanced adenoviral delivery of RNA interference in ovarian carcinoma cell lines

“…Other methods of delivery employed in the literature include the use of polyethylenimine [21] and protamine [22]. Other viral vectors including the Retrovirus and Adeno-associated virus have also been used for delivery [23,24]. Now that RNAi strategies are becoming the method of choice for in vitro gene knockdown, the technique of in vivo delivery will need to be perfected.…”