[Neuroendocrine tumors of the lungs. From small cell lung carcinoma to diffuse idiopathic pulmonary neuroendocrine cell hyperplasia]

MicroRNA‑629 inhibition suppresses the viability and invasion of non‑small cell lung cancer cells by directly targeting RUNX3

Dysregulated microRNAs (miRNAs/miRs) directly modulate the biological functions of non‑small cell lung cancer (NSCLC) cells and contribute to the initiation and progression of NSCLC; however, the specific roles and underlying mechanisms of the dysregulated miRNAs in NSCLC require further investigation. The present study reported that miRNA‑629‑5p (miR‑629) was upregulated in NSCLC tissues and cell lines. High miR‑629 expression levels were significantly associated with tumour size, clinical stage and lymph node metastasis in patients with NSCLC. Functional experiments indicated that miR‑629 inhibition suppressed the viability and invasion NSCLC cells in vitro. Furthermore, bioinformatics prediction, luciferase reporter assay, reverse transcription‑quantitative polymerase chain reaction and western blot analysis demonstrated that runt‑related transcription factor 3 (RUNX3) was a direct target gene of miR‑629 in NSCLC. Restoration of RUNX3 expression suppressed the effects of miR‑629 inhibition in NSCLC cells. Rescue experiments revealed that RUNX3 knockdown partially abrogated the effects of miR‑629 inhibition on NSCLC cells. In summary, miR‑629 directly targeted RUNX3 to inhibit the progression of NSCLC, suggesting that this miRNA may be considered as a diagnostic and therapeutic target for patients with NSCLC.

miR‑185 inhibits non‑small cell lung cancer cell proliferation and invasion through targeting of SOX9 and regulation of Wnt signaling

SRY-box 9 (SOX9) is an important transcription factor required for development, which has additionally been reported to be an independent prognostic indicator for the survival of patients with non‑small cell lung cancer (NSCLC). Accumulating evidence has indicated that dysregulation of microRNAs (miRNAs/miRs) may contribute to the initiation and progression of cancer. SOX9 may be regulated by a number of miRNAs in different types of cancer, including in NSCLC. The present study sought to identify novel candidate miRNAs associated with SOX9 in NSCLC using online tools, and investigated the detailed functions of miR‑185, which suppressed SOX9 mRNA expression most strongly out of the candidate miRNAs. It was observed that ectopic miR‑185 expression significantly suppressed NSCLC cell proliferation, invasion and migration. Using luciferase reporter gene and RNA immunoprecipitation assays, SOX9 was confirmed to be a direct target of miR‑185. In addition, the downstream Wnt signaling‑associated factors β‑catenin and c‑Myc proto‑oncogene protein (Myc) were demonstrated to be inhibited by miR‑185 overexpression. SOX9, β‑catenin and c‑Myc mRNA expression was significantly upregulated in NSCLC tissues, and was inversely correlated with miR‑185 expression. The results of the present study demonstrated that rescuing miR‑185 expression in NSCLC, thereby inhibiting SOX9 expression and the downstream Wnt signaling, and leading to the suppression of NSCLC cell proliferation, invasion and migration, may be a promising strategy for the treatment of NSCLC.

Pituitary sex hormones enhance the pro‑metastatic potential of human lung cancer cells by downregulating the intracellular expression of heme oxygenase‑1

We report that human lung cancer cell lines express functional receptors for pituitary sex hormones (SexHs) and respond to stimulation by follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL). Expression of these receptors has also been confirmed in patient lung cancer samples at the mRNA level. Stimulation of human lung cancer cell lines with FSH, LH, or PRL stimulated migration and chemotaxis, and some cell lines responded by enhanced proliferation. Moreover, priming of human lung cancer cells by exposing them to pituitary SexHs resulted in enhanced seeding efficiency of injected human lung cancer cells into bone marrow, liver, and lungs in an immunodeficient mouse model. The chemotaxis of lung cancer cell lines corresponded with the activity of heme oxygenase-1 (HO-1), as stimulation of these cells by FSH, LH, and PRL downregulated its expression in a p38 MAPK-dependent manner. Moreover, while downregulation of HO-1 by the small-molecule inhibitor tin protoporphyrin (SnPP) promoted migration, upregulation of HO-1 by the small-molecule activator cobalt protoporphyrin (CoPP) showed the opposite effect. Based on this finding, we propose that pituitary SexHs play a significant role in the pathogenesis of lung cancer, particularly when the blood level of FSH increases due to gonadal dysfunction with advanced age. Finally, we propose that upregulation of HO-1 expression by a small-molecule activator may be effective in controlling SexH-induced cell migration in lung cancer.

[Pulmonary neuroendocrine tumors in the new WHO 2015 classification: Start of breaking new grounds?]

CLASSIFICATION

In the recently published 4th edition of the World Health Organization (WHO) classification of tumors of the lungs, pleura, thymus and heart, all neuroendocrine tumors of the lungs (pNET) are presented for the first time in one single chapter following adenocarcinoma and squamous cell carcinoma and before large cell carcinoma. In this classification, high grade small cell lung cancer (SCLC) and large cell neuroendocrine carcinoma (LCNEC) are differentiated from intermediate grade atypical carcinoids (AC) and low grade typical carcinoids as well as from preinvasive lesions (DIPNECH). In the 3rd WHO classification from 2004, which dealt with resection specimens, SCLC and carcinoids each had a separate chapter and LCNEC was previously listed in the chapter on large cell carcinoma of the lungs. The new WHO classification is for the first time also applicable to lung biopsies.

DIAGNOSTICS

Normally, common features of all pNET are a neuroendocrine morphology (as far as detectable in small biopsies) and expression of the neuroendocrine (NE) markers (chromogranin A, synaptophysin and CD56/NCAM). An immunohistochemical positive staining of at least one NE marker was already recommended in the 3rd edition of the WHO classification (2004) only for LCNEC. Differentiating features are a small or large cell cytomorphology/histomorphology, nuclear criteria and the mitotic rate (for SCLC >10 with a median of 80, for LCNEC >10 median 70, for AC 2 - 10, for TC < 2 each per 2 mm(2)). Tumor cell necrosis usually occurs in SCLC and LCNEC, partially in AC and not in TC. The guideline Ki67 proliferation rates are given for the first time in the new WHO classification for SCLC as 50-100 %, for LCNEC 40-80 %, for AC up to 20 % and for TC up to 5 %.

MOLECULAR PATHOLOGY

Molecular alterations occur in SCLC and LCNEC in large numbers and are very variable in quality. In AC and TC they occur much less frequently and are relatively similar.

CONCLUSION

The direct comparison of all pNET in one chapter facilitates the differential diagnostics of these tumors, provides a better transparency especially of LCNEC and allows a further comprehensive development of the clinical practical and scientific evaluation of pNET. Although a separate terminology of pNET is maintained for the lungs, a careful approach towards the gastroentero-pancreatic NET (gepNET) can be observed.