microRNA Profile in Early-stage Cervical Cancer

Cervical carcinoma (CC) is one of the most common cancers in women from countries with emerging economies; in Mexico, CC has the second highest incidence and mortality rate. Several studies have demonstrated that the most important prognostic factor is lymph node metastasis in early-stage CC patients prior to radical hysterectomy (RH) with bilateral pelvic lymphadenectomy (BPL), in which positive lymph node metastasis decreasing overall survival (OS) from 80% to 53% at 5 years.

MicroRNAs (miRNAs) are single-strand RNAs comprising approximately 21-23 nucleotides. miRNAs regulate gene expression through the inhibition of posttranscriptional events and, in some cases, induce the degradation of their target messenger RNA. In cancer, miRNAs can function as both oncogenes and/or as tumor suppressor genes depending on the function of their target genes.

Formalin-fixed paraffin-embedded (FFPE) tissue blocks from CC patients diagnosed between January 2006 and December 2013 at the Department of Oncologic Gynecology of the National Cancer Institute (Mexico City) were analyzed with the intention of selecting those with a confirmed histopathological diagnosis of stages IB1 or IIA1 CC treated with RH and BPL. Total RNA was extracted from 5 (10-µm) sections for selected tissues.For the clinical correlation analysis, the samples were divided into 2 groups: 1 with positive occult lymph node metastasis pathology and 1 without lymph node metastasis pathology. For both groups, patients were matched for age, tumor size and presence of lymphovascular permeation.

The identification of global miRNA profiles was performed using GeneChip miRNA 3.0 Array (Affymetrix, Cat. 902018) following the manufacturer's instructions. the microarray was hybridized and washed using the Affymetrix Fluidics Station 450 and scanned with the Affymetrix GeneChip Scanner 3000. After processing the images, the raw data were processed. To obtain the miRNA profile, the processed samples were divided into 2 groups, samples with lymph node metastasis and samples without lymph node metastasis. Differentially expressed miRNAs were identified using a cutoff value of p <0.01 and a fold change (FC) of 1.5. miRNAs that met these criteria were classified as over-expressed or under-expressed.

Inclusion criteria

• Cervical cancer histopathological diagnosis
• Clinical stage IB1 or IIA1 CC
• Treated with radical hysterectomy (RH) with bilateral pelvic lymphadenectomy (BPL)

Exclusion criteria

• Double primary tumors
• Treatment regimens other than standard treatment
• Poor quality formalin-fixed paraffin-embedded tissue blocks