Long Non-Coding RNAs and Their Potential Roles in the Vector-Host-Pathogen Triad.

Long non-coding (lnc)RNAs have emerged as critical regulators of gene expression and are involved in almost every cellular process. They can bind to other molecules including DNA, proteins, or even other RNA types such messenger RNA or small RNAs. LncRNAs are typically expressed at much lower levels than mRNA, and their expression is often restricted to tissue- or time-specific developmental stages. They are also involved in several inter-species interactions, including vector-host-pathogen interactions, where they can be either vector/host-derived or encoded by pathogens. In these interactions, they function via multiple mechanisms including regulating pathogen growth and replication or via cell-autonomous antimicrobial defense mechanisms. Recent advances suggest that characterizing lncRNAs and their targets in different species may hold the key to understanding the role of this class of non-coding RNA in interspecies crosstalk. In this review, we present a general overview of recent studies related to lncRNA-related regulation of gene expression as well as their possible involvement in regulating vector-host-pathogen interactions.

Salivary microRNAs identified by small RNA sequencing as potential predictors of response to intensity-modulated radiotherapy in head and neck cancer patients.

PURPOSE: Progress in radiation therapy of head and neck squamous cell carcinomas (HNSCCs) is logically linked to the development of molecular predictors that would help to enhance individually tailored treatment. MicroRNA (miRNA) expression profiles in tumors have repeatedly been tested to optimize the molecular diagnostics of HNSCC. In addition to tumor tissues, miRNAs are stably present in body fluids, including saliva, and can thus be collected non-invasively. The aim of our current study was to evaluate whether salivary miRNAs have potential as response predictors in HNSCC patients treated with intensity modulated radiation therapy (IMRT). METHODS: In total 48 HNSCC patients treated by definitive IMRT were enrolled in our prospective study. To identify predictive salivary miRNAs, we used small RNA sequencing in 14 saliva samples of HNSCC patients and qRT-PCR validation of selected miRNA candidates in an independent set of 34 patients. RESULTS: We found that salivary miR-15a-5p and miR-15b-5p exhibited differential levels between patients with and without complete remission (p = 0.025 and p = 0.028, respectively). Subsequent Kaplan-Meier analysis confirmed that patients with higher levels of miR-15a-5p reached a significantly longer locoregional progression-free survival (LPFS) than those with low levels (p = 0.024). Finally, multivariate Cox regression analysis revealed that miR-15a-5p may serve as an independent predictive biomarker of LPFS in HNSCC patients treated with IMRT (HR 0.104; 95% CI 0.004-0.911; p = 0.04). CONCLUSIONS: We conclude that salivary miR-15a-5p may represent a potential biomarker for individualized treatment decision-making in HNSCC patients.

MicroRNA-15b-5p Predicts Locoregional Relapse in Head and Neck Carcinoma Patients Treated With Intensity-modulated Radiotherapy.

BACKGROUND/AIM: Head and neck cancers are a heterogenous group of epithelial tumors represented mainly by squamous cell carcinomas (HNSCC), which are the sixth most common type of cancer worldwide. Surgery together with radiotherapy (RT) is among the basic treatment modalities for most HNSCC patients. Various biomarkers aiming to predict patients' response to RT are currently investigated. The reason behind this effort is, on one hand, to distinguish radioresistant patients that show weak benefit from RT and, on the other hand, reduce the ionizing radiation dose in less aggressive radiosensitive HNSCC with possibly less acute or late toxicity. MATERIALS AND METHODS: A total of 94 HNSCC patients treated by definitive intensity-modulated radiotherapy were included in our retrospective study. We used a global expression analysis of microRNAs (miRNAs) in 43 tumor samples and validated a series of selected miRNAs in an independent set of 51 tumors. RESULTS: We identified miR-15b-5p to be differentially expressed between patients with short and long time of locoregional control (LRC). Kaplan-Meier analysis confirmed that HNSCC patients with higher expression of miR-15b-5p reach a significantly longer locoregional relapse-free survival compared to patients expressing low levels. Finally, multivariable Cox regression analysis revealed that miR-15b-5p is an independent predictive biomarker of LRC in HNSCC patients (HR=0.25; 95% CI=0.05-0.78; p<0.016). CONCLUSION: miR-15b-5p represents a potentially helpful biomarker for individualized treatment decisions concerning the management of HNSCC patients.

Expression of CD44, EGFR, p16, and their mutual combinations in patients with head and neck cancer: Impact on outcomes of intensity-modulated radiation therapy.

BACKGROUND: Progress in radiation treatment of head and neck squamous cell carcinoma (HNSCC) deserves the studies focused on molecular predictors that would help to enhance individually tailored treatment. METHODS: p16/epidermal growth factor receptor (EGFR)/cluster of differentiation-44 (CD44) was immunohistochemically analyzed in 165 HNSCC patients. RESULTS: In the entire group and the p16 negative cohort, better 3-year overall survival and locoregional control correlated with p16 positivity, CD44, and EGFR negativity were observed. Combined analysis revealed the worst results in the CD44+/p16-, EGFR+/p16-, and EGFR+/CD44+ groups and in the EGFR+/CD44+ within p16 negative cohort. Multivariate analysis found tumor stage, Karnofsky index, p16, and CD44 as prognostic factors of overall survival and clinical stage, and p16 as a prognostic factor for locoregional control. Clinical stage and Karnofsky index affected overall survival and tumor stage. EGFR affected locoregional control in the p16 negative subgroup. CONCLUSION: Our study confirmed the negative effect of CD44 and EGFR and the positive effect of p16 on radiotherapy results.

Prognostic impact of combined immunoprofiles in oropharyngeal squamous cell carcinoma patients with respect to AJCC 8th edition.

OBJECTIVES: To examine combined immunoprofiles of epidermal growth factor receptor (EGFR), CD44, and p16 in oropharyngeal squamous cell carcinoma (OPSCC) and to correlate them with radiotherapy treatment outcomes and clinicopathological parameters. Prognostic impact of the American Joint Committee on Cancer (AJCC) 8th edition staging system in comparison with 7th edition was analyzed. METHODS: The study included 77 OPSCC patients treated by definitive intensity-modulated radiotherapy (IMRT). Clinical staging was assessed according to the AJCC, both 7th and 8th edition. Immunohistochemical (IHC) analysis of CD44 and EGFR was performed on primary biopsy tumor tissues. To evaluate the HPV status, IHC detection of p16 was employed. RESULTS: The AJCC 8th edition staging system revealed correlations between overall survival (OS), progression-free survival (PFS), locoregional control (LRC), and clinical stage. EGFR and CD44 positivity (+) and p16 negativity (-) were associated with clinical stage IV of the disease. CD44+ and EGFR+ OPSCC displayed worse OS and LRC, and these cases also showed the worst 3-year OS and LRC. Combined analysis of protein expressions identified an association between p16- and EGFR+, p16- and CD44+, EGFR+, and CD44+. Combined immunoprofiles CD44+/p16-, EGFR+/p16-, and EGFR+/CD44+ were associated with worst OS and LRC. CONCLUSIONS: Combined immunoprofiles of p16, EGFR, and CD44 might provide valuable prognostic and predictive information for the individual OPSCC patients, especially in terms of response to IMRT and prediction of treatment outcomes. Application of the AJCC 8th edition staging for HPV+ OPSCC proved to improve hazard discrimination and prognostication of OPSCC.

MicroRNAs Involvement in Radioresistance of Head and Neck Cancer.

Resistance to the ionizing radiation is a current problem in the treatment and clinical management of various cancers including head and neck cancer. There are several biological and molecular mechanisms described to be responsible for resistance of the tumors to radiotherapy. Among them, the main mechanisms include alterations in intracellular pathways involved in DNA damage and repair, apoptosis, proliferation, and angiogenesis. It has been found that regulation of these complex processes is often controlled by microRNAs. MicroRNAs are short endogenous RNA molecules that posttranscriptionally modulate gene expression and their deregulated expression has been observed in many tumors including head and neck cancer. Specific expression patterns of microRNAs have also been shown to predict prognosis and therapeutic response in head and neck cancer. Therefore, microRNAs present promising biomarkers and therapeutic targets that might overcome resistance to radiation and improve prognosis of head and neck cancer patients. In this review, we summarize the current knowledge of the functional role of microRNAs in radioresistance of cancer with special focus on head and neck cancer.