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RNA interference is a natural mechanism to silence post-transcriptional gene expression in eukaryotic cells in which microRNAs act to cleave or halt the translation of target mRNAs at specific target sequences. Mature microRNAs, 19-25 nucleotides in length, mediate their effect at the mRNA level by inhibiting translation, or inducing cleavage of the mRNA target. This process is directed by the degree of complementary nucleotides between the microRNAs and the target mRNA; perfect complementary base pairing induces cleavage of mRNA, whereas several mismatches lead to translational arrest. Biological effects of microRNAs can be manipulated through the use of small interference RNAs (siRNAs) generated by chemical synthesis, or by cloning in molecular vectors. The cloning of a DNA insert in a molecular vector that will be transcribed into the corresponding siRNAs is an approach that has been developed using siRNA expression plasmids. These vectors contain DNA inserts designed with software to generate highly efficient siRNAs which will assemble into RNA-induced silencing complexes (RISC), and silence the target mRNA. In addition, the DNA inserts may be contained in cloning cassettes, and introduced in other molecular vectors. In this chapter we describe an attractive technology platform to silence cellular gene expression using specific siRNA expression plasmids, and evaluate its biological effect on target gene expression in human cervical cancer cells.

Cervical cancer is the second most common cause of death from cancer in women worldwide, and the development of new diagnostic, prognostic, and treatment strategies merits special attention. Many efforts have been made to design new drugs and develop immunotherapy and gene therapy strategies to treat cervical cancer. HPV genotyping has potentially valuable applications in triage of low-grade abnormal cervical cytology, assessment of prognosis and followup of cervical intraepithelial neoplasia, and in treatment strategies for invasive cervical cancer. It is known that during the development of cervical cancer associated with HPV infection, a cascade of abnormal events is induced, including disruption of cellular cycle control, alteration of gene expression, and deregulation of microRNA expression. Thus, the identification and subsequent functional evaluation of host proteins associated with HPV E6 and E7 oncoproteins may provide useful information in understanding cervical carcinogenesis, identifying cervical cancer molecular markers, and developing specific targeting strategies against tumor cells. Therefore, in this paper, we discuss the main diagnostic methods, management strategies, and followup of HPV-associated cervical lesions and review clinical trials applying gene therapy strategies against the development of cervical cancer.