Circulating microRNAs: next-generation biomarkers for early lung cancer detection

Circulating plasma microRNAs as potential markers to identify EGFR mutation status and to monitor epidermal growth factor receptor-tyrosine kinase inhibitor treatment in patients with advanced non-small cell lung cancer

We aimed to identify a panel of circulating plasma microRNAs that can predict EGFR mutation status and monitor epidermal growth factor receptor-tyrosine kinase inhibitor treatment in patients with non-small cell lung cancer. Microarrays were performed for the preliminary screening of dysregulated microRNAs in 9 EGFR mutation-positive patients versus healthy controls. MiR-107 was upregulated and miR-195 was downregulated in the exon 19 deletion versus wild-type group. The areas under the receiver operating characteristic curves for miR-107, miR-195, and a panel of these 2 microRNAs were 0.72, 0.75, and 0.74, with sensitivities and specificities of 64.7% and 76.6%, 71.8% and 69.1%, and 71.7% and 78.9%, respectively. MiR-122 was significantly upregulated in the p.L858R versus wild-type group. An area under the receiver operative characteristic curve of 0.75 suggests that miR-122 might be a specific biomarker for patients with the p.L858R mutation. In addition, dynamic changes in these 3 microRNAs were also found to correlate with responses to epidermal growth factor receptor-tyrosine kinase inhibitor treatment, indicating that circulating plasma microRNAs may represent potential biomarkers for monitoring epidermal growth factor receptor-tyrosine kinase inhibitor treatment. This study demonstrates the prospective application of circulating plasma microRNAs as potential non-invasive, convenient biomarkers for patients with EGFR-sensitive mutations.

Epigenetics in non-small cell lung cancer: from basics to therapeutics

Lung cancer remains the number one cause of cancer-related deaths worldwide with 221,200 estimated new cases and 158,040 estimated deaths in 2015. Approximately 80% of cases are non-small cell lung cancer (NSCLC). The diagnosis is usually made at an advanced stage where the prognosis is poor and therapeutic options are limited. The evolution of lung cancer is a multistep process involving genetic, epigenetic, and environmental factor interactions that result in the dysregulation of key oncogenes and tumor suppressor genes, culminating in activation of cancer-related signaling pathways. The past decade has witnessed the discovery of multiple molecular aberrations that drive lung cancer growth, among which are epidermal growth factor receptor (EGFR) mutations and translocations involving the anaplastic lymphoma kinase (ALK) gene. This has translated into therapeutic agent developments that target these molecular alterations. The absence of targetable mutations in 50% of NSCLC cases and targeted therapy resistance development underscores the importance for developing alternative therapeutic strategies for treating lung cancer. Among these strategies, pharmacologic modulation of the epigenome has been used to treat lung cancer. Epigenetics approaches may circumvent the problem of tumor heterogeneity by affecting the expression of multiple tumor suppression genes (TSGs), halting tumor growth and survival. Moreover, it may be effective for tumors that are not driven by currently recognized druggable mutations. This review summarizes the molecular pathology of lung cancer epigenetic aberrations and discusses current efforts to target the epigenome with different pharmacological approaches. Our main focus will be on hypomethylating agents, histone deacetylase (HDAC) inhibitors, microRNA modulations, and the role of novel epigenetic biomarkers. Last, we will address the challenges that face this old-new strategy in treating lung cancer.

Expression of miR-29c, miR-93, and miR-429 as potential biomarkers for detection of early stage non-small lung cancer

BACKGROUND

Altered expression of miRNA expression contributes to human carcinogenesis. This study was designed to detect aberrant miRNA expressions as a potential biomarker for early detection and prognosis prediction of non-small cell lung cancer (NSCLC).

METHODS

miRNA array was used to profile differentially expressed miRNAs and Taqman-based quantitative RT-PCR assays were used to analyze levels of miR-29c, miR-93, and miR-429 expression in NSCLC tissue samples, corresponding normal tissue samples, and serum samples from 70 NSCLC patients as well as in serum samples from 48 healthy controls.

RESULTS

Levels of miR-29c and miR-93 expression were upregulated in NSCLC tissues, while serum levels of miR-29c were also upregulated, but levels of serum miR-429 were decreased in NSCLC. Moreover, the levels of miR-429 expression in NSCLC tissues were associated with those in serum samples. Receiver operating characteristic (ROC) curve analysis showed that at the optimal cut-off point, the areas under the ROC curve for serum levels of miR-29c and miR-429 were 0.723 and 0.727, respectively, levels which are higher than that of carcinoma embryonic antigen (0.534) in diagnosis of stage I NSCLC. In addition, serum levels of miR-429 were associated with poor overall survival of NSCLC patients. Both univariate and multivariate analyses showed that serum miR-429 level was an independent prognostic predictor for NSCLC.

CONCLUSIONS

The results of the current study suggest that detection of serum miR-29c and miR-429 expression should be further evaluated as a novel, non-invasive biomarker for early stage NSCLC.

Lung cancer biomarkers: State of the art

Lung cancer is one of the deadliest cancers worldwide, with the highest incidence and mortality amongst all cancers. While the prognosis of lung cancer is generally grim, with 5-year survival rates of only 15%, there is hope, and evidence, that early detection of lung cancer can reduce mortality. Today, only computed tomography screening has shown to lead to early detection and reduction in mortality, but is limited by being anatomic in nature, unable to differentiate between inflammatory and neoplastic pathways, and therefore, susceptible to false positives. There is increasing interest in biomarkers for lung cancer, especially those that predict metastatic risk. Some biomarkers like DNA mutations and epigenetic changes potentially require tissue from the at-risk site; some like serum proteins and miRNAs are minimally invasive, but may not be specific to the lung. In comparison, emerging biomarkers from exhaled breath, like volatile organic compounds (VOC), and exhaled breath condensate, e.g., small molecules and nucleic acids, have the potential to combine the best of both. This mini review is intended to provide an overview of the field, briefly discussing the potential of what is known and highlighting the exciting recent developments, particularly with miRNAs and VOCs.