Detection of metastatic head and neck squamous cell carcinoma using the relative expression of tissue-specific mir-205

A miR-centric view of head and neck cancers

Head and Neck Squamous Cell Carcinomas (HNSCCs) constitute the sixth most common cancer worldwide with an average 5-year survival rate of around 50%. Several microRNAs, small non-coding RNAs involved in post-transcriptional gene regulation, have been linked to HNSCC based on their differential expression in tumors. Here, we present a compilation of multiple types of information on each HNSCC linked miRNA including their expression status in tumors, their molecular targets relevant to cancer, results of gene manipulation studies and association with clinical outcome. Further, we use this information to devise a new scheme for classifying them into causal and non-causal miRNAs in HNSCC. We also discuss the possibility of using miRNAs as prognostic and diagnostic biomarkers for HNSCC, based on existing literature. Finally, we present available evidence that shows how altered expression of specific miRNAs can contribute to various "hallmarks of cancer" phenotypes such as limitless replicative potential owing to abnormal cell cycle regulation, evasion of apoptosis, reduced response to anti-growth signals, and Epithelial-Mesechymal transition (EMT).

The ups and downs of miR-205: identifying the roles of miR-205 in mammary gland development and breast cancer

Recent studies have demonstrated that miR-205 has a role in both normal development and cancer, however conflicting reports on its function illustrate the complexity of its regulation and targets. Additionally, miR-205 was found to be highly expressed in stem cell-enriched populations from the mouse mammary gland, and thus may play a function in normal mammary stem cell maintenance. The role that miR-205 plays in tumor formation and metastasis is likely context-dependent as reports have indicated that it may function as either a tumor suppressor or an oncogene. The role that miR-205 plays in directing stem cell fate is still unknown.

Ultra-high throughput sequencing-based small RNA discovery and discrete statistical biomarker analysis in a collection of cervical tumours and matched controls

BACKGROUND

Ultra-high throughput sequencing technologies provide opportunities both for discovery of novel molecular species and for detailed comparisons of gene expression patterns. Small RNA populations are particularly well suited to this analysis, as many different small RNAs can be completely sequenced in a single instrument run.

RESULTS

We prepared small RNA libraries from 29 tumour/normal pairs of human cervical tissue samples. Analysis of the resulting sequences (42 million in total) defined 64 new human microRNA (miRNA) genes. Both arms of the hairpin precursor were observed in twenty-three of the newly identified miRNA candidates. We tested several computational approaches for the analysis of class differences between high throughput sequencing datasets and describe a novel application of a log linear model that has provided the most effective analysis for this data. This method resulted in the identification of 67 miRNAs that were differentially-expressed between the tumour and normal samples at a false discovery rate less than 0.001.

CONCLUSIONS

This approach can potentially be applied to any kind of RNA sequencing data for analysing differential sequence representation between biological sample sets.

microRNA evaluation of unknown primary lesions in the head and neck

Unknown primary malignancy in the head and neck is not an infrequent diagnosis for patients with metastatic cervical lymph nodes. Although linked with a relatively good prognosis following radiation treatment, widespread radiation is coupled with significant morbidity. Altered microRNA (miRNA) expression has been associated with both cancer progression and metastasis. We sought to determine whether miRNA expression analysis could be used as a diagnostic tool to discover the primary site of malignancy, within the head and neck. We used quantitative real-time PCR to identify miRNA expression profiles of squamous cell carcinoma of the tonsil, base of tongue and post-nasal space, as well as their corresponding metastatic lymph nodes, from 6 patients. Our results revealed that each cancer maintained its expression profile between the primary site and the nodal metastasis (r = 0.82, p < 0.0001). In addition, each anatomical sub-site maintained a distinct miRNA profile between individual patients (r = 0.79, p < 0.0001). Finally, between sub-sites, the miRNA profiles were distinct (p < 0.0001). As proof of principle, our study provides an indication that miRNA expression analysis may be useful to compare the primary lesion and local metastatic disease. This may be clinically relevant to predict the primary site of origin of metastatic disease, when the primary site remains obscure.

MicroRNA profiling and head and neck cancer

Head and neck/oral cancer (HNOC) is a devastating disease. Despite advances in diagnosis and treatment, mortality rates have not improved significantly over the past three decades. Improvement in patient survival requires a better understanding of the disease progression so that HNOC can be detected early in the disease process and targeted therapeutic interventions can be deployed. Accumulating evidence suggests that microRNAs play important roles in many human cancers. They are pivotal regulators of diverse cellular processes including proliferation, differentiation, apoptosis, survival, motility, and morphogenesis. MicroRNA expression patterns may become powerful biomarkers for diagnosis and prognosis of HNOC. In addition, microRNA therapy could be a novel strategy for HNOC prevention and therapeutics. Recent advances in microRNA expression profiling have led to a better understanding of the cancer pathogenesis. In this review, we will survey recent technological advances in microRNA profiling and their applications in defining microRNA markers/targets for cancer prediction, diagnostics, treatment, and prognostics. MicroRNA alterations that consistently identified in HNOC will be discussed, such as upregulation of miR-21, miR-31, miR-155, and downregulation of miR-26b, miR-107, miR-133b, miR-138, and miR-139.

CYP1A2*1C, CYP2E1*5B, and GSTM1 polymorphisms are predictors of risk and poor outcome in head and neck squamous cell carcinoma patients

Head and neck squamous cell carcinoma (HNSCC) is associated with environmental factors, especially tobacco and alcohol consumption. Most of the carcinogens present in tobacco smoke are converted into DNA-reactive metabolites by cytochrome P450 (CYPs) enzymes and detoxification of these substances is performed by glutathione S-transferases (GSTs). It has been suggested that genetic alterations, such as polymorphisms, play an important role in tumorigenesis and HNSCC progression. The aim of this study was to investigate CYP1A1, CYP1A2, CYP2E1, GSTM1, and GSTT1 polymorphisms as risk factors in HNSCC and their association with clinicopathologic data. The patients comprised 153 individuals with HNSCC (cases) and 145 with no current or previous diagnosis of cancer (controls). Genotyping of the single nucleotide polymorphisms (SNPs) of the CYP1A1, CYP1A2, and CYP2E1 genes was performed by PCR-RFLP and the GSTM1 and GSTT1 copy number polymorphisms (CNPs) were analyzed by PCR-multiplex. As expected, a significant difference was detected for tobacco and alcohol consumption between cases and controls (P<0.001). It was observed that the CYP1A2*1D (OR=16.24) variant and GSTM1 null alleles (OR=0.02) confer increased risk of HNSCC development (P<0.001). In addition, head and neck cancer alcohol consumers were more frequently associated with the CYP2E1*5B variant allele than control alcohol users (P<0.0001, OR=190.6). The CYP1A2*1C polymorphism was associated with tumor recurrence (log-rank test, P=0.0161). The CYP2E1*5B and GSTM1 null alleles were significantly associated with advanced clinical stages (T3+T4; P=0.022 and P=0.028, respectively). Overall, the findings suggested that the genetic polymorphisms studied are predictors of risk and are also associated with tumor recurrence, since they are important for determining the parameters associated with tumor progression and poor outcomes in HNSCC.

MicroRNAs--the micro steering wheel of tumour metastases

Recently, microRNAs (miRNAs) have been discovered to have a role in metastasis. Here we describe how miRNAs are involved in advanced stages of tumour progression, stressing their roles as metastasis activators or suppressors, and discuss their possible use in the clinic as predictive markers and as therapeutic strategies for patients with metastases. Furthermore, we develop the concept that the same miRNAs could be involved both in the cancer stem cell phenotype and in the ability of specific cancer cells to produce metastases, thus representing a mechanistic link between the initial and the final steps of tumorigenesis.

Evolving 'omics' technologies for diagnostics of head and neck cancer

Squamous cell carcinoma of head and neck (SCCHN) is the sixth most common malignancy and is a major cause of cancer morbidity and mortality worldwide. As with most solid cancers, the cure rate for SCCHN is excellent if tumors are diagnosed early in the course of the disease. Early diagnosis of cancer remains difficult because of the lack of specific symptoms in early disease as well as the limited understanding of etiology and oncogenesis. Advances in proteomics and genomics contribute to the understanding of the pathophysiology of neoplasia, cancer diagnosis and anticancer drug discovery. The powerful 'omics' technologies have opened new avenues towards biomarker discovery, identification of signaling molecules associated with cell growth, cell death, cellular metabolism and early detection of cancer. Analysis of tumor-specific omics profiles provided a unique opportunity to diagnose, classify, and detect malignant disease; to better understand and define the behavior of specific tumors; and to provide direct and targeted therapy. These technologies however still require integration and standardization of techniques and validation against accepted clinical and pathologic parameters. This article provides a summary of technologies, potential clinical applications, and challenges of omics in head and neck cancer.