Identification and characterization of Dicer1e, a Dicer1 protein variant, in oral cancer cells

Abstract

BackgroundThe human dicer1 gene has been predicted to produce several mRNA variants that encode truncated Dicer1 proteins of varying lengths. One of these Dicer1 variants, Dicer1e, was recently found to be differentially expressed in breast cancer cells. Because the expression and function of the Dicer1e protein variant has not been well characterized and the underlying molecular mechanisms for the development of oral squamous cell carcinomas (OSCCs) are poorly understood, the present study sought to characterize the biological role of Dicer1e and determine its relationship, if any, to OSCC pathogenesis.MethodsWestern blot analyses were used to examine Dicer1e expression levels in a panel of oral cancer cells/tissues and during epithelial-mesenchymal transition (EMT), followed by 5′/3′-RACE analyses to obtain the full-length Dicer1e transcript. Biochemical fractionation and indirect immunofluorescent studies were performed to determine the cellular localization of Dicer1e and the effects of Dicer1e silencing on cancer cell proliferation, clonogenicity, and drug sensitivity were also assessed.ResultsDicer1e protein levels were found to be overexpressed in OSCC cell lines of epithelial phenotype and in OSCC tissues with its levels downregulated during EMT. Moreover, the Dicer1e protein was observed to predominantly localize in the nucleus. 5′/3′-RACE analyses confirmed the presence of the Dicer1e transcript and silencing of Dicer1e impaired both cancer cell proliferation and clonogenicity by inducing either apoptosis and/or G2/M cell cycle arrest. Lastly, Dicer1e knockdown enhanced the chemosensitivity of oral cancer cells to cisplatin.ConclusionThe expression levels of Dicer1e influence the pathogenesis of oral cancer cells and alter their response to chemosensitivity, thus supporting the importance of Dicer1e as a therapeutic target for OSCCs.Electronic supplementary materialThe online version of this article (doi:10.1186/1476-4598-13-190) contains supplementary material, which is available to authorized users.

Unknown Areas of Activity of Human Ribonuclease Dicer: A Putative Deoxyribonuclease Activity

“…Moreover, numerous shorter variants have been identified. One of the examples is Dicer1e transcript variant encoding an 820 amino acid (93-kDa) truncated form of hDicer [43]. This truncated hDicer variant comprises only RNase IIIa and IIIb domains, and the dsRBD.…”

Differential expression of hsa-miR-221, hsa-miR-21, hsa-miR-135b, and hsa-miR-29c suggests a field effect in oral cancer

“…In OSCC, a low Dicer expression may influence the pathogenesis of oral cancer cells and was significantly correlated with the pathological response to chemoradiotherapy. Furthermore, Dicer was suggested as a potential biomarker for predicting the clinical response and a therapeutic target for OSCCs [ 57 – 59 ].…”

Slicing and dicing viruses: antiviral RNA interference in mammals

“…Together, these data suggest that the helicase domain of Dicer inhibits its catalytic activity for long dsRNA and that its incorporation into the mature enzyme might be regulated by alternative transcription. However, expression of Dicer O has not been detected outside mouse germ cells and expression of truncated Dicer isoforms in humans has been reported only in certain cancer cell lines (Potenza et al, ; Hinkal et al, ; Cantini et al, ). An alternative possibility is that modulation of inhibition by the helicase domain could come about not through alternative transcription but through the activity of Dicer‐associated proteins.…”