Dysregulation of
microRNAs has been studied thoroughly, and has been observed in a variety of
tumors including vulvar
carcinomas, a rare type of gynecological
tumor with increasing incidence. However, very few therapeutic alternatives have reached the clinical setting, and there is an urgent unmet need to develop novel strategies for patients with this
tumor type. Thus, a
microRNA (
miRNA) sponge for the miR-17
miRNA family was designed, synthesized and validated in vitro in order to explore a new therapeutic strategy based on inhibiting this oncogenic
miRNA family in
vulvar cancer. Members of the miR-17 family were evaluated for expression in a vulvar tumor cell line (SW954) and 20 HPV negative
formalin-fixed
paraffin-embedded (FFPE) samples by quantitative real-time PCR (qRT-PCR). Six in tandem, bulged sequences that were complementary to these
miRNAs were designed, synthesized, cloned, and transfected into SW954 cells. A
luciferase reporter assay with a psiCheck2 vector was used to test the specificity of the sponge sequences for miR-17 family
miRNA binding. Taqman qRT-PCR was used to test how the sponges affected
miRNA expression. In FFPE samples, higher expression of miR-20a and miR-106a correlated with deeper
tumor invasion (P = 0.0187 and P = 0.0404, respectively). The
luciferase reporter assay validated the specificity of the sponge for miR-17 family members. Using qRT-PCR, we confirmed this specificity with decreased expression in 5 (out of six)
miRNAs of the miR-17 family in SW954 cells. Although our results are preliminary, these results demonstrate that these
miRNA sponges are potent inhibitors of the miR-17 family of
miRNAs in SW954. Therefore, this
miRNA-specific sponge may be developed into a novel therapeutic treatment for patients with
vulvar cancer.