MicroRNA expression signature of oral squamous cell carcinoma: functional role of microRNA-26a/b in the modulation of novel cancer pathways

Background:

MicroRNAs (miRNAs) have been shown to play major roles in carcinogenesis in a variety of cancers. The aim of this study was to determine the miRNA expression signature of oral squamous cell carcinoma (OSCC) and to investigate the functional roles of miR-26a and miR-26b in OSCC cells.

Methods:

An OSCC miRNA signature was constructed by PCR-based array methods. Functional studies of differentially expressed miRNAs were performed to investigate cell proliferation, migration, and invasion in OSCC cells. In silico database and genome-wide gene expression analyses were performed to identify molecular targets and pathways mediated by miR-26a/b.

Results:

miR-26a and miR-26b were significantly downregulated in OSCC. Restoration of both miR-26a and miR-26b in cancer cell lines revealed that these miRNAs significantly inhibited cancer cell migration and invasion. Our data demonstrated that the novel transmembrane TMEM184B gene was a direct target of miR-26a/b regulation. Silencing of TMEM184B inhibited cancer cell migration and invasion, and regulated the actin cytoskeleton-pathway related genes.

Conclusions:

Loss of tumour-suppressive miR-26a/b enhanced cancer cell migration and invasion in OSCC through direct regulation of TMEM184B. Our data describing pathways regulated by tumour-suppressive miR-26a/b provide new insights into the potential mechanisms of OSCC oncogenesis and metastasis.     

Circulating microRNAs as prognostic therapy biomarkers in head and neck cancer patients

Background:

The prediction of therapy response in head and neck squamous cell cancer (HNSCC) requires biomarkers, which are also a prerequisite for personalised therapy concepts. The current study aimed to identify therapy-responsive microRNAs (miRNAs) in the circulation that can serve as minimally invasive prognostic markers for HNSCC patients undergoing radiotherapy.

Methods:

We screened plasma miRNAs in a discovery cohort of HNSCC patients before therapy and after treatment. We further compared the plasma miRNAs of the patients to age- and sex-matched healthy controls. All miRNAs identified as biomarker candidates were then confirmed in an independent validation cohort of HNSCC patients and tested for correlation with the clinical outcome.

Results:

We identified a signature of eight plasma miRNAs that differentiated significantly (P=0.003) between HNSCC patients and healthy donors. MiR-186-5p demonstrated the highest sensitivity and specificity to classify HNSCC patients and healthy individuals. All therapy-responsive and patient-specific miRNAs in plasma were also detectable in tumour tissues derived from the same patients. High expression of miR-142-3p, miR-186-5p, miR-195-5p, miR-374b-5p and miR-574-3p in the plasma correlated with worse prognosis.

Conclusions:

Circulating miR-142-3p, miR-186-5p, miR-195-5p, miR-374b-5p and miR-574-3p represent the most promising markers for prognosis and therapy monitoring in the plasma of HNSCC patients. We found strong evidence that the circulating therapy-responsive miRNAs are tumour related and were able to validate them in an independent cohort of HNSCC patients.     

microRNAs in uterine sarcomas and mixed epithelial–mesenchymal uterine tumors: a preliminary report

Uterine sarcomas and mixed epithelial–mesenchymal uterine tumors are a heterogeneous group of rare tumors for which there are very few diagnostic markers available. As aberrant microRNA (miRNA) expression patterns represent putative diagnostic cancer markers, we aimed to identify miRNA expression profiles of the major uterine sarcoma subtypes and mixed epithelial–mesenchymal tumors of the uterus. Eighty-eight miRNAs were assessed by quantitative RT-PCR in cancerous and non-cancerous tissue samples collected from 29 patients with endometrial sarcoma, leiomyosarcoma, and mixed epithelial–mesenchymal tumors. Tumor and control samples significantly (P?<?0.05) differed in the expression of miR-23b, miR-1, let-7f, and let-7c in endometrial sarcomas, and miR-1, let-7c, miR-133b, let-7b, miR-143, let-7a, let-7d, let-7e, let-7g, miR-222, let-7i, and miR-214 in mixed epithelial–mesenchymal tumors. All the significantly changed miRNAs were down-regulated in the malignant tissues as compared to their normal counterparts. This may suggest their tumor suppressor role in these malignancies. No statistically significant changes in miRNA expression levels were found between leiomyosarcoma tumors and controls. The identified miRNAs warrant further studies as valuable candidate markers for the differential diagnosis of uterine sarcomas from benign uterine lesions and between uterine sarcoma subtypes.     

Differential expression of miR-139, miR-486 and miR-21 in breast cancer patients sub-classified according to lymph node status

Purpose

Therapeutic decisions in breast cancer are increasingly guided by prognostic and predictive biomarkers. Non-protein-coding microRNAs (miRNAs) have recently been found to be deregulated in breast cancers and, in addition, to be correlated with several clinico-pathological features. One of the most consistently up-regulated miRNAs is miR-21. Here, we specifically searched for differentially expressed miRNAs in high-risk breast cancer patients as compared to low-risk breast cancer patients. In the same patients, we also compared miR-21 expression with the expression of its presumed target PTEN.

Methods

Both microarray and RT-qPCR techniques were used to assess miRNA expression levels in lymph node-positive and -negative human invasive ductal carcinoma tissues. Simultaneously, PTEN protein expression levels were assessed using immunohistochemistry.

Results

miR-486-5p and miR-139-5p were found to be down-regulated in patients with lymph node metastases, whereas miR-21 was found to be up-regulated in patients with a positive lymph node status. miR-21 expression levels were found to significantly correlate with tumour size (r?=?0.403, p?=?0.009; Spearman’s rank), whereas no relation was found between miR-21 and PTEN expression levels (Kruskal-Wallis test).

Conclusion

Down-regulation of miR-486-5p and miR-139-5p, in conjunction with up-regulation of miR-21, may represent a useful signature for the identification of high-risk breast cancer patients.     

MicroRNA signatures predict oestrogen receptor, progesterone receptor and HER2/neu receptor status in breast cancer

Introduction

Breast cancer is a heterogeneous disease encompassing a number of phenotypically diverse tumours. Expression levels of the oestrogen, progesterone and HER2/neu receptors which characterize clinically distinct breast tumours have been shown to change during disease progression and in response to systemic therapies. Mi(cro)RNAs play critical roles in diverse biological processes and are aberrantly expressed in several human neoplasms including breast cancer, where they function as regulators of tumour behaviour and progression. The aims of this study were to identify miRNA signatures that accurately predict the oestrogen receptor (ER), progesterone receptor (PR) and HER2/neu receptor status of breast cancer patients to provide insight into the regulation of breast cancer phenotypes and progression.

Methods

Expression profiling of 453 miRNAs was performed in 29 early-stage breast cancer specimens. miRNA signatures associated with ER, PR and HER2/neu status were generated using artificial neural networks (ANN), and expression of specific miRNAs was validated using RQ-PCR.

Results

Stepwise ANN analysis identified predictive miRNA signatures corresponding with oestrogen (miR-342, miR-299, miR-217, miR-190, miR-135b, miR-218), progesterone (miR-520g, miR-377, miR-527-518a, miR-520f-520c) and HER2/neu (miR-520d, miR-181c, miR-302c, miR-376b, miR-30e) receptor status. MiR-342 and miR-520g expression was further analysed in 95 breast tumours. MiR-342 expression was highest in ER and HER2/neu-positive luminal B tumours and lowest in triple-negative tumours. MiR-520g expression was elevated in ER and PR-negative tumours.

Conclusions

This study demonstrates that ANN analysis reliably identifies biologically relevant miRNAs associated with specific breast cancer phenotypes. The association of specific miRNAs with ER, PR and HER2/neu status indicates a role for these miRNAs in disease classification of breast cancer. Decreased expression of miR-342 in the therapeutically challenging triple-negative breast tumours, increased miR-342 expression in the luminal B tumours, and downregulated miR-520g in ER and PR-positive tumours indicates that not only is dysregulated miRNA expression a marker for poorer prognosis breast cancer, but that it could also present an attractive target for therapeutic intervention.     

Systemic miRNA‐195 Differentiates Breast Cancer from Other Malignancies and Is a Potential Biomarker for Detecting Noninvasive and Early Stage Disease

Purpose.

The potential of microRNAs (miRNAs) as novel tumor markers has been the focus of recent scrutiny because of their tissue specificity, stability, and association with clinicopathological parameters. Data have emerged documenting altered systemic miRNA expression across a spectrum of cancers; however, it remains uncertain as to whether circulating miRNAs are tumor specific. Our aim was to assess a panel of cancer-associated miRNAs in the circulation of patients with various malignancies, to determine whether these “oncomirs” were tumor specific, and thus to establish whether systemic miRNA analysis has utility in cancer diagnosis.

Patients and Methods.

Whole blood samples were prospectively collected from preoperative cancer patients (breast, prostate, colon, and renal cancer and melanoma; n = 163) and healthy age- and sex-matched controls (n = 63). Total RNA was isolated, and a panel of seven miRNAs was quantified by real-time quantitative polymerase chain reaction in each sample.

Results.

Differential expression of the general oncomirs let 7a, miR-10b, and miR-155, was observed in the majority of cancer patients in a nonspecific manner. Significantly, elevated circulating miR-195 was found to be breast cancer specific and could differentiate breast cancer from other cancers and from controls with a sensitivity of 88% at a specificity of 91%. A combination of three circulating miRNAs, including miR-195, further enhanced the discriminative power of this test for breast cancer to 94%.

Conclusion.

These findings suggest that individual cancers display specific systemic miRNA profiles, which could aid in discriminating among cancer types. This finding is of notable clinical consequence because it illustrates the potential of systemic miRNAs as sensitive, specific, noninvasive cancer biomarkers.     

The microRNA-23b/27b/24-1 cluster is a disease progression marker and tumor suppressor in prostate cancer

Our recent study of microRNA (miRNA) expression signatures in prostate cancer (PCa) has revealed that all members of the miR-23b/27b/24-1 cluster are significantly downregulated in PCa tissues. The aim of this study was to investigate the effectiveness of these clustered miRNAs as a disease progression marker and to determine the functional significance of these clustered miRNAs in PCa. Expression of the miR-23b/27b/24-1 cluster was significantly reduced in PCa tissues. Kaplan-Meier survival curves showed that low expression of miR-27b predicted a short duration of progression to castration-resistant PCa. Gain-of-function studies using mature miR-23b, miR-27b, and miR-24-1 significantly inhibited cell proliferation, migration and invasion in PCa cells (PC3 and DU145). To identify the molecular targets of these miRNAs, we carried out gene expression and in silico database analyses. GOLM1 was directly regulated by miR-27b in PCa cells. Elucidation of the molecular targets and pathways regulated by the tumor-suppressive microRNAs should shed light on the oncogenic and metastatic processes in PCa.     

The tumour-suppressive function of miR-1 and miR-133a targeting TAGLN2 in bladder cancer

Background:

On the base of the microRNA (miRNA) expression signature of bladder cancer (BC), we found that miR-1 and miR-133a were significantly downregulated in BC. In this study, we focussed on the functional significance of miR-1 and miR-133a in BC cell lines and identified a molecular network of these miRNAs.

Methods and results:

We investigated the miRNA expression signature of BC clinical specimens and identified several downregulated miRNAs (miR-133a, miR-204, miR-1, miR-139-5p, and miR-370). MiR-1 and miR-133a showed potential role of tumour suppressors by functional analyses of BC cells such as cell proliferation, apoptosis, migration, and invasion assays. Molecular target searches of these miRNAs showed that transgelin 2 (TAGLN2) was directly regulated by both miR-1 and miR-133a. Silencing of TAGLN2 study demonstrated significant inhibitions of cell proliferation and increase of apoptosis in BC cell lines. The immunohistochemistry showed a positive correlation between TAGLN2 expression and tumour grade in clinical BC specimens.

Conclusions:

The downregulation of miR-1 and miR-133a was a frequent event in BC, and these miRNAs were recognised as tumour suppressive. TAGLN2 may be a target of both miRNAs and had a potential oncogenic function. Therefore, novel molecular networks provided by miRNAs may provide new insights into the underlying molecular mechanisms of BC.     

The quantitative analysis by stem-loop real-time PCR revealed the microRNA-34a, microRNA-155 and microRNA-200c overexpression in human colorectal cancer

The recently identified class of microRNAs (miRNAs) provided a new insight in cancer research. As the member of miRNAs family, miR-34a, miR-155 and miR-200c abnormalities have been found in various types of cancer. However, the relationship between these three miRNAs (miR-34a, miR-155 and miR-200c) and colorectal cancer is unclear. In this study, we applied stem-loop real-time PCR to quantitatively detect miR-34a, miR-155 and miR-200c expression in 109 pair-matched human colorectal cancers and the corresponding normal mucosa. MiR-34a (2.2-fold), miR-155 (2.3-fold) and miR-200c (3.1-fold) were all expressed at higher levels in colorectal cancer (P?=?0.001, 0.005 and 0.001, respectively). In rectum, miR-34a and miR-200c were significantly upregulated (P?=?0.006 and 0.007), while the miR-155 overexpression was not statistically significant (P?=?0.083). In colon, the higher expression of three miRNAs was seen, however, without significant difference (P?>?0.05). We also found that the miR-34a expression was higher in rectal cancer having more advanced TNM stage (III?+?IV, P?=?0.03). Then miR-200c expression was positively correlated with and sera CEA level of rectal cancer patients (P?=?0.04). In conclusion, our results thus suggest that the overexpression of miR-34a, miR-155 and miR-200c be associated with the development of colorectal cancer, meanwhile miR-34a may be involved in the development and progression of rectal cancer. The more deeply and larger scale research are required to prove the correlation.     

Changes in microRNA (miRNA) expression during pancreatic cancer development and progression in a genetically engineered KrasG12D;Pdx1-Cre mouse (KC) model

Differential expression of microRNAs (miRNAs) has been demonstrated in various cancers, including pancreatic cancer (PC). Due to the lack of tissue samples from early-stages of PC, the stage-specific alteration of miRNAs during PC initiation and progression is largely unknown. In this study, we investigated the global miRNA expression profile and their processing machinery during PC progression using the Kras^G12D;Pdx1-Cre (KC) mouse model. At 25 weeks, the miRNA microarray analysis revealed significant downregulation of miR-150, miR-494, miR-138, miR-148a, miR-216a, and miR-217 and upregulation of miR-146b, miR-205, miR-31, miR-192, and miR-21 in KC mice compared to controls. Further, expression of miRNA biosynthetic machinery including Dicer, Exportin-5, TRKRA, and TARBP2 were downregulated, while DGCR8 and Ago2 were upregulated in KC mice. In addition, from 10 to 50 weeks of age, stage-specific expression profiling of miRNA in KC mice revealed downregulation of miR-216, miR-217, miR-100, miR-345, miR-141, miR-483-3p, miR-26b, miR-150, miR-195, Let-7b and Let-96 and upregulation of miR-21, miR-205, miR-146b, miR-34c, miR-1273, miR-223 and miR-195 compared to control mice. Interestingly, the differential expression of miRNA in mice also corroborated with the miRNA expression in human PC cell lines and tissue samples; ectopic expression of Let-7b in CD18/HPAF and Capan1 cells resulted in downregulation of KRAS and MSST1 expression. Overall, the present study aids an understanding of miRNA expression patterns during PC pathogenesis and helps to facilitate the identification of promising and novel early diagnostic/prognostic markers and therapeutic targets.     

Circulatory miR-628-5p is downregulated in prostate cancer patients

Prostate cancer (PCa) is a major health concern for men in the USA. Aberrant expression of microRNAs (miRNAs) has been associated with the pathogenesis of various cancers, including PCa. Circulatory forms of miRNAs have been detected in serum and hold promise as minimally invasive cancer biomarkers. This study aimed to identify potential circulatory miRNAs that can provide insights into new mechanisms for clinical diagnosis of PCa and can serve as potential biomarkers and/or therapeutic targets. Candidate serum miRNAs were detected by using PCR microarray in a learning set of six African American (AA) and six Caucasian American (CA) PCa patients. Discriminating performance of candidate miRNAs was validated by qRT-PCR in serum samples from 36 AA (24 PCa patients and 12 controls) and 36 CA (16 PCa patients and 20 controls). From the miRNA profiling experiments, three differentially expressed miRNAs (miR-25, miR-101, and miR-628-5p) were selected for future validation. In the validation set, there was an overall low expression of miR-25 (p?<?0.01), miR-101 (p?<?0.001), and miR-628-5p (p?<?0.0001) in serum of PCa patients as compared with normal individuals. Subdivision on the basis of ethnicity showed that serum expression levels of miR-628-5p were significantly downregulated in both AA and CA PCa patients when compared with their respective controls. Our results demonstrate that the three miRNAs, particularly miR-628-5p, may be further developed as a biomarker, which can serve as novel noninvasive biomarker for PCa diagnosis and prognosis.     

Exosomal microRNA in serum is a novel biomarker of recurrence in human colorectal cancer

Background:

Functional microRNAs (miRNAs) in exosomes have been recognised as potential stable biomarkers in cancers. The aim of this study is to identify specific miRNAs in exosome as serum biomarkers for the early detection of recurrence in human colorectal cancer (CRC).

Methods:

Serum samples were sequentially obtained from six patients with and without recurrent CRC. The miRNAs were purified from exosomes, and miRNA microarray analysis was performed. The miRNA expression profiles and copy number aberrations were explored using microarray and array CGH analyses in 124 CRC tissues. Then, we validated exosomal miRNAs in 2 serum sample sets (90 and 209 CRC patients) by quantitative real-time RT–PCR.

Results:

Exosomal miR-17-92a cluster expression level in serum was correlated with the recurrence of CRC. Exosomal miR-19a expression levels in serum were significantly increased in patients with CRC as compared with healthy individuals with gene amplification. The CRC patients with high exosomal miR-19a expression showed poorer prognoses than the low expression group (P<0.001).

Conclusions:

Abundant expression of exosomal miR-19a in serum was identified as a prognostic biomarker for recurrence in CRC patients.     

Tumour-suppressive microRNA-29s inhibit cancer cell migration and invasion by targeting laminin–integrin signalling in head and neck squamous cell carcinoma

Background:

Our recent studies of microRNA (miRNA) expression signatures demonstrated that microRNA-29s (miR-29s; miR-29a/b/c) were significantly downregulated in head and neck squamous cell carcinoma (HNSCC) and were putative tumour-suppressive miRNAs in human cancers. Our aim in this study was to investigate the functional significance of miR-29s in cancer cells and to identify novel miR-29s-mediated cancer pathways and responsible genes in HNSCC oncogenesis and metastasis.

Methods:

Gain-of-function studies using mature miR-29s were performed to investigate cell proliferation, migration and invasion in two HNSCC cell lines (SAS and FaDu). To identify miR-29s-mediated molecular pathways and targets, we utilised gene expression analysis and in silico database analysis. Loss-of-function assays were performed to investigate the functional significance of miR-29s target genes.

Results:

Restoration of miR-29s in SAS and FaDu cell lines revealed significant inhibition of cancer cell migration and invasion. Gene expression data and in silico analysis demonstrated that miR-29s modulated the focal adhesion pathway. Moreover, laminin γ2 (LAMC2) and α6 integrin (ITGA6) genes were candidate targets of the regulation of miR-29s. Luciferase reporter assays showed that miR-29s directly regulated LAMC2 and ITGA6. Silencing of LAMC2 and ITGA6 genes significantly inhibited cell migration and invasion in cancer cells.

Conclusion:

Downregulation of miR-29s was a frequent event in HNSCC. The miR-29s acted as tumour suppressors and directly targeted laminin–integrin signalling. Recognition of tumour-suppressive miRNA-mediated cancer pathways provides new insights into the potential mechanisms of HNSCC oncogenesis and metastasis and suggests novel therapeutic strategies for the disease.     

High copy number variation of cancer-related microRNA genes and frequent amplification of DICER1 and DROSHA in lung cancer

A growing body of evidence indicates that miRNAs may be a class of genetic elements that can either drive or suppress oncogenesis. In this study we analyzed the somatic copy number variation of 14 miRNA genes frequently found to be either over- or underexpressed in lung cancer, as well as two miRNA biogenesis genes, DICER1 and DROSHA, in non-small-cell lung cancer (NSCLC). Our analysis showed that most analyzed miRNA genes undergo substantial copy number alteration in lung cancer. The most frequently amplified miRNA genes include the following: miR-30d, miR-21, miR-17 and miR-155. We also showed that both DICER1 and DROSHA are frequently amplified in NSCLC. The copy number variation of DICER1 and DROSHA correlates well with their expression and survival of NSCLC and other cancer patients. The increased expression of DROSHA and DICER1 decreases and increases the survival, respectively. In conclusion, our results show that copy number variation may be an important mechanism of upregulation/downregulation of miRNAs in cancer and suggest an oncogenic role for DROSHA.     

Circulating microRNAs as novel prognosis biomarkers for head and neck squamous cell carcinoma

Circulating microRNAs (miRNAs) are emerging as promising non-invasive biomarkers for human cancer. Head and neck squamous cell carcinoma (HNSCC) is a prevalent malignancy worldwide, but its overall survival has remained unchanged in the past 3 decades. Biomarkers for evaluating efficacy of cancer therapy are urgently needed. To explore circulating miRNAs as cancer therapy biomarkers, we initially identified that 8 miRNAs were distinctly dysregulated in cancerous tissues compared with adjacent non-cancerous counterparts from 16 patients, using microarray and real-time PCR. Based on this discovery, the comparison study was performed between pre- and 6 months post-operative paired plasma samples on 9 patients. MiR-99a, which was down-regulated in cancerous tissues, was significantly increased in plasma after operation. Meanwhile, oncomiR miR-21 and miR-223 that were up-regulated in cancerous tissues, were significantly reduced in post-operative plasma samples. We firstly report the significant changes of miR-99a in plasma of HNSCC patients after surgery. Furthermore, plasma miR-223 was inversely increased in a patient whose cancer relapsed within 6 months after operation. We conclude that these circulating miRNAs may serve as biomarkers to evaluate the efficacy of therapy and the prognosis of HNSCC.     

Higher circulating expression levels of miR-221 associated with poor overall survival in renal cell carcinoma patients

The mechanisms involved in renal cell carcinoma (RCC) development and progression remain unclear, and new biomarkers for early detection, follow-up of the disease and prognosis are needed in routine practice to improve the diagnostic and/or prognostic accuracy. There is increasing evidence that microRNAs (miRNAs) are involved in cancer development and progression. The up-regulation of miR-221/222 has been described in several human cancers, and during RCC development, this up-regulation can modulate the metastatic process. Our purpose was to investigate the circulating expression levels of miR-221/222 as potential biomarkers for RCC detection and their influence in patients' overall survival. The circulating miR-221/222 was studied by relative quantification in 77 plasma samples. A follow-up study was undertaken to evaluate the overall survival. We observed that RCC patients presented higher circulating expression levels of miR-221 and miR-222 than healthy individuals (2^?ΔΔCt = 2.8, P?=?0.028; 2^?ΔΔCt = 2.2, P?=?0.044, respectively). The RCC patients with metastasis at diagnosis also presented higher circulating expression levels of miR-221 than patients with no metastasis (2^?ΔΔCt = 10.9, P?=?0.001). We also observed a significantly lower overall survival in patients with higher expression levels of miR-221 (48 vs 116 months, respectively; P?=?0.024). Furthermore, multivariate Cox regression analysis using the tumour, nodes and metastasis stage (TNM stage); Fuhrman nuclear grade and age (≥60 years) as covariants demonstrated a higher risk of specific death by cancer in patients who presented higher expression levels of miR-221 (hazard ratio (HR) = 10.7, 95 % confidence interval 1.33–85.65, P?=?0.026). The concordance (c) index showed that the definition of profiles that contain information regarding tumour characteristics associated with circulating miR-221 expression information presents an increased capacity to predict the risk of death by RCC (c index model 1, 0.800 vs model 2, 0.961). Our results, which identified the plasma miR-221/222 at variable levels during RCC development, suggest that these miRNAs may have a potential as noninvasive biomarkers of RCC development.     

Expression analysis of three miRNAs,miR-26a,miR-29b and miR-519d,in relation to <Emphasis Type="Italic">MMP</Emphasis>-<Emphasis Type="Italic">2</Emphasis> expression level in non-small cell lung cancer patients: a pilot study

Lung cancer is the most common cause of death in men and second only to breast cancer in women. MicroRNAs (miRNAs) are involved in tumorigenesis and function as oncogenes or tumor suppressor genes. Among other genes, miRNAs regulate matrix metalloproteinases (MMPs), the proteolytic enzymes playing a significant role in the degradation of extracellular matrix, enhancing tumor invasion and metastasis. The aim of the study was to evaluate the expression levels of selected miRNAs: miR-26a, miR-29b and miR-519d, and their target gene, matrix metalloproteinase-2 (MMP-2) in patients with non-small cell lung cancer (NSCLC). The results were correlated with tumor staging, NSCLC histopathological subtypes and patients’ demographical features to assess the possible diagnostic/prognostic value of the studied miRNAs and MMP-2. Total RNA was isolated from 38 NSCLC tissue samples, and the expression analysis was performed using TaqMan^® probes in qPCR assay. The results indicated underexpression of selected miRNAs and overexpression of MMP-2. The decrease in miRNA-29b expression was statistically significant and differentiated NSCLC histopathological subtypes. Additionally, statistically significant negative correlation was found between MMP-2 expression and its regulatory miR-26a. There are very few studies reporting miRNA-MMPs analysis on mRNA level in lung cancer, and no similar reports are available from Polish population. The results of our pilot study indicated the diagnostic potential of miR-29b and MMP-2, an inverse association between miR-26a and MMP-2, and proved the role of MMP-2 and the studied miRNAs in lung carcinogenesis. Further studies are needed to verify their potential usefulness for the treatment of lung cancer.