MicroRNA alterations in head and neck squamous cell carcinoma

Abstract

MicroRNAs (mirs) are small non-coding RNA molecules (~22 nucleotides) that regulate post-transcriptional gene expression. Currently, there has not been a comprehensive study of their role in primary HNSCC. To determine the role of mirs in head and neck squamous cell carcinoma (HNSCC), we screened for altered microRNA expression in HNSCC primary tissue and cell lines. We then further tested the functional impact of alterations of specific mirs. An initial screening of 4 primary HNSCC, 4 normal mucosal controls and 4 HNSCC cell lines were analyzed for mature microRNA expression by microarray. Significance was determined using Significance Analysis of Microarrays (SAM). Nine microRNAs were found by SAM to be up-regulated or down-regulated in tumor tissue including mir-21,let-7,18,29c,142-3p,155,146b(over-expressed) and 494(under-expressed). Mir-21 was validated by qRT-PCR. Functional validation by growth assays was performed, further validating mir-21. Transfection of mir-21 into JHU-011 and JHU-012 cell lines showed a 39% increase in cell growth at 72 hrs relative to controls (p<.05). Transfection of the inhibitor into JHU-O12 cell lines showed a 92% decrease in cell growth relative to controls at 72hrs (p<.05). In addition, flow cytometry analysis of JHU-012 cells 48 hrs after mir-21 inhibitor transfection showed a statistically significantly increase in cytochrome c release and increased apoptosis. These differentially expressed microRNAs may be of interest as potential novel oncogenes and tumor suppressor genes in HNSCC. Mir-21 is a putative oncogenic microRNA in head and neck cancer.

hsa‐miR‐210 is a marker of tumor hypoxia and a prognostic factor in head and neck cancer

“…We found that hsamiR-21 was higher in tumor than normal tissue, in keeping with previous studies showing its overexpression in HNSCC. 23 hsa-miR-10b expression was lower in tumor than normal tissue, again in keeping with our previous result in breast cancer, 32 and that of Childs et al in HNSCC, 33 but conflicting with the finding of Ma et al 18 Given our previous finding that the adjacent normal tissue had a lower hypoxia score by metagene than its matched tumor, 7 we were expecting that hsa-miR-210 would be lower in normal than in tumor tissue. However, for hsamiR-210, expression in some tumors was higher than matched normal tissue, and expression in others was lower.…”

“…One of the best described microRNAs related to cellular proliferation and apoptosis is micro-RNA-21 (hsa-miR-21). 21 hsa-miR-21 is overexpressed in many cancers, including HNSCC, 22,23 and is associated with a poor prognosis in nonsmall cell lung cancer. 24 Its targets include the tumor suppressors phosphatase and tensin homolog, 25 tropomysin 1, 26 and programmed cell death 4.…”

Foxo3a Regulates Apoptosis by Negatively Targeting miR-21

“…miR-21 is higher in estrogen receptor-␣-positive tumors, and estradiol inhibits miR-21 expression in MCF-7 human breast cancer cells (28). miR-21 is abundantly expressed and is a putative oncogenic miRNA in head and neck cancer (29). Overexpression of miR-21 can be observed in multiple myeloma and is associated with its pathogenesis (30).…”

Phospho-ΔNp63α is a key regulator of the cisplatin-induced microRNAome in cancer cells

“…14,15 Altered expression of miRNA genes has been found in a variety of tumor types and has shown the oncogenic, tumor-suppressive, or apoptotic potential of specific miRNAs. [16][17][18][19] Certain miRNAs were shown to mediate the induction of cell death, cell cycle arrest, and senescence and contribute to epithelial stem cell maturation. [18][19][20] We previously observed that the head and neck squamous cell carcinoma (HNSCC) cells exposed to CIS displayed a dramatic downregulation of DNp63a through an ATMdependent phosphorylation mechanism.…”