Assessment of the Expression of Long Noncoding Mitochondrial RNAs (lncmtRNAs) During Cervical Cancer Progression and Cervical Carcinoma

Abstract

Objective: Cervical cancer is the second most common cancer in women with high rates of mortality worldwide. Cervical cancer is slowly progressive and is preceded by pre-invasive intraepithelial lesions. Therefore, detection of premalignant lesions is key to preventing disease progression to advanced stages. The objective of the present study was examination and quantification of the differentially expressed non-coding mitochondrial RNAs during progression of disease. Material and methods:The differential expression of S-ncmtRNA and AS-ncmtRNA was analyzed by in situ hybridization (ISH) using tissue macroarrays (TMA) from normal, CIN1, CIN2, CIN3 and invasive squamous carcinoma (SCC). PCNA and p16INK-4a were detected in consecutive biopsies by immunohistochemistry. Quantification of ISH signal was carried out with Image ProPlus 6.1 software and the results were expressed as percentage of Integrated Optical Density (IOD). Results:We found a marked down-regulation of AS-ncmtRNA in 95% of tissues analyzed (CIN 1/2, CIN 3, and invasive squamous cancer). Moreover, differential expression of ASncmtRNA v/s S-ncmtRNA showed significant difference. Normal proliferating tissues did not display down-regulation of AS-ncmtRNA. Down regulation of ASncmtRNA correlated with the expression of the tumor suppressor protein p16INK-4a Conclusions:We found down-regulation of AS-ncmtRNA in pre-malignant and tumor samples which could distinguish normal tissues from early lesions and tumor samples. These results suggest that the down-regulation of AS-ncmtRNA is a novel marker of early lesions and cervix neoplasia. Previously, we reported that human cells express a unique family of mitochondrial long ncmtRNAs (ncmtRNAs) [12,13]. One of these transcripts, named sense ncmtRNA (SncmtRNA) is expressed in normal proliferating cells and tumor cells but not in resting cells, suggesting a functional role in cell cycle progression [12]. Normal proliferating cells express, in addition to the S-ncmtRNA, two antisense mitochondrial ncmtRNAs (AS-ncmtRNA-1 and AS-ncmtRNA-2) where both AS-ncmtRNAs are down-regulated in human cancer cells regardless of tissue of origin. In order to analyze the expression pattern of these ncmtRNAs in cervical cancer, we performed a qualitative pilot study in cervical biopsies encompassing the progression of the disease. We found that AS-ncmtRNAs are down-regulated in mild, moderate and severe neoplasia and in invasive cervical carcinoma [14]. In the present study a quantitative analysis of the differential expression of the S-ncmtRNA and the ASncmtRNAs was performed in biopsies of CIN1 to CIN3 and invasive cervical carcinoma, correlating it with the expression of the tumor suppressor p16 Assessment of the Expression of LongINK 4A and proliferating cell nuclear antigen (PCNA). Methods Tissue specimensAll the tissues were purchased from Pantomics Inc. (Richmond, CA, USA), corresponding to Tissue Macroarrays (TMA) containing normal cervix, CIN1, CIN2, CIN3 and invasive squamous carcinoma (SCC). For normal specimens,...

HPV-18 E2 protein downregulates antisense noncoding mitochondrial RNA-2, delaying replicative senescence of human keratinocytes

“…In a challenging review, Bellanger et al discussed the possibility of pleiotropic characteristic of HPV E2 functioning as either tumor suppressor or oncogene [5]. The present results confirm that the HPV E2 protein behaves as a tumor suppressor at least in cervical cancer and that downregulation of the ASncmtRNAs constitutes an important step in carcinogenesis [12,15–17,25]. However, which cellular factor(s) induces downregulation of the ASncmtRNAs in non-HPV induced cancers remains unclear.…”

Long Noncoding Mitochondrial RNAs (LncmtRNAs) as Targets for Cancer Therapy

“…Moreover, differential expression of ASncmtRNA v/s S-ncmtRNA showed significant difference, while, as expected, normal proliferating tissues did not display downregulation of ASncmtRNAs. Moreover, downregulation of ASncmtRNAs correlated with the over-expression of the tumor suppressor protein p16INK-4a [48,49].…”

Key Molecular Events in Cervical Cancer Development

“…Proliferating cell nuclear antigen (PCNA) is most relevant in cell proliferation and is involved in the radiation-repair genes (RAD6)-dependent DNA repair pathway [51]. Several studies using immunohistochemistry and microarray found that expression of PCNA increased as the disease progressed [46,52,53,54].…”