Expression of Mir-21 and Mir-143 in Cervical Specimens Ranging from Histologically Normal through to Invasive Cervical Cancer

MicroRNA expression is severely disrupted in carcinogenesis, however limited evidence is available validating results from cell-line models in human clinical cancer specimens. MicroRNA-21 (mir-21) and microRNA-143 (mir-143) have previously been identified as significantly deregulated in a range of cancers including cervical cancer. Our goal was to investigate the expression patterns of several well-studied microRNA species in cervical samples and compare the results to cell line samples.We measured the expression of mir-21 and mir-143 in 142 formalin-fixed, paraffin embedded (FFPE) cervical biopsy tissue blocks, collected from Dantec Oncology Clinic, Dakar, Senegal. MicroRNA expression analysis was performed using Taqman-based real-time PCR assays. Protein immunohistochemical staining was also performed to investigate target protein expression on 72 samples. We found that mir-21 expression increased with worsening clinical diagnosis but that mir-143 was not correlated with histology. These observations were in stark contrast to previous reports involving cervical cancer cell lines in which mir-143 was consistently down-regulated but mir-21 largely unaffected. We also identified, for the first time, that cytoplasmic expression of Programmed Cell Death Protein 4 PDCD4; a known target of mir-21) was significantly lower in women with invasive cervical carcinoma (ICC) in comparison to those with cervical intraepithelial neoplasia (2-3) or carcinoma in situ (CIN2-3/CIS), although there was no significant correlation between mir-21 and PDCD4 expression, despite previous studies identifying PDCD4 transcript as a known mir-21 target.Whilst microRNA biomarkers have a number of promising features, more studies on expression levels in histologically defined clinical specimens are required to investigate clinical relevance of discovery-based studies. Mir-21 may be of some utility in predictive screening, given that we observed a significant correlation between mir-21 expression level and worsening histological diagnosis of cervical cancer

MicroRNA expression in FFPE cervical specimens.

<p>*ANOVA.</p

Micrographs showing PDCD4 staining of (a) Normal (HRHVP-) specimen and (b) ICC specimen.

<p>Micrographs showing PDCD4 staining of (a) Normal (HRHVP-) specimen and (b) ICC specimen.</p

Protein expression results for 72 clinical samples.

<p>*ANOVA.</p

Protein expression data measured by immunohistochemistry for cytoplasmic PDCD4 stratified by histological diagnosis.

<p>Here we observed a significant association between cytoplasmic PDCD4 expression and sample histology.</p

Expression profiling data for mir-21 and mir-143 in cervical cancer cell lines and normal specimens.

<p>Mir-143 was significantly down-regulated in all three cervical cancer cell lines, in agreement with previous studies. However, mir-21 was not significantly different to the normal specimens, even though in previous studies mir-21 has been observed to be significantly up-regulated in the same cell lines.</p