Expression profiling of components of the miRNA maturation machinery

Circular RNA expression in basal cell carcinoma

Aim: Circular RNAs (circRNAs), are nonprotein coding RNAs consisting of a circular loop with multiple miRNA, binding sites called miRNA response elements (MREs), functioning as miRNA sponges. This study was performed to identify differentially expressed circRNAs and their MREs in basal cell carcinoma (BCC). Materials & methods: Microarray circRNA expression profiles were acquired from BCC and control followed by qRT-PCR validation. Bioinformatical target prediction revealed multiple MREs. Sequence analysis was performed concerning MRE interaction potential with the BCC miRNome. Results: We identified 23 upregulated and 48 downregulated circRNAs with 354 miRNA response elements capable of sequestering miRNA target sequences of the BCC miRNome. Conclusion: The present study describes a variety of circRNAs that are potentially involved in the molecular pathogenesis of BCC.

Inflammation induced changes in the expression levels of components of the microRNA maturation machinery Drosha, Dicer, Drosha co-factor DGRC8 and Exportin-5 in inflammatory lesions of hidradenitis suppurativa patients

BACKGROUND

The inflammatory pathogenesis behind the debilitating chronic inflammatory skin disorder hidradenitis suppurativa (HS) is poorly understood. Deregulation of microRNAs (miRNAs) may contribute to the pathogenesis and chronic inflammation in autoimmune and inflammatory diseases. However, there are no data on the expression or function of miRNAs in HS.

OBJECTIVE

To evaluate expression of the miRNA key regulators Drosha, Drosha co-factor DGRC8, Dicer and Exportin-5 in the inflammatory microenvironment of HS.

METHODS

Specimens were harvested from lesional HS skin (n=18), adjacent healthy-appearing HS skin (n=7), lesional psoriatic skin (n=10), and healthy subjects (n=10). To evaluate the quantitative real-time RT-PCR data of Drosha and Dicer a subset of skin samples were studied by immunohistochemistry.

RESULTS

Drosha and DGRC8 were significantly downregulated in healthy-appearing perilesional skin from HS patients compared to healthy controls. There were no significant differences in Drosha, DGRC8 and Exportin-5 expression between lesional HS and lesional psoriatic skin. Notably, Dicer expression levels were not dysregulated in psoriatic skin.

LIMITATIONS

Small sample size and descriptive study design.

CONCLUSIONS

The miRNA key regulators were significantly dysregulated in HS lesions compared to healthy skin. Drosha and DGRC8 are altered in the initial, subclinical inflammatory process in healthy-appearing perilesional skin of HS patients prior to the first visible clinical manifestations. Dicer and Exportin-5 may contribute to the later inflammatory process with visible HS lesions.

Next-generation sequencing of the basal cell carcinoma miRNome and a description of novel microRNA candidates under neoadjuvant vismodegib therapy: an integrative molecular and surgical case study

BACKGROUND

MicroRNAs (miRNAs) have been identified as key players in posttranscriptional gene regulation and have a significant impact on basal cell carcinoma (BCC) development. The Sonic hedgehog pathway inhibitor vismodegib has been approved for oral therapy of metastatic or advanced BCC. Here, a high-throughput miRNA sequencing analysis was carried out to identify differentially expressed miRNAs and possible novel miRNA candidates in vismodegib-treated BCC tissue. Additionally, we described our surgical experience with neoadjuvant oral vismodegib therapy.

PATIENTS AND METHODS

A punch biopsy (4 mm) from a patient with an extensive cranial BCC under oral vismodegib therapy and a corresponding nonlesional epithelial skin biopsy were harvested. Total RNA was isolated, after which a sequencing cDNA library was prepared, and cluster generation was carried out, which was followed by an ultra-high-throughput miRNA sequencing analysis to indicate the read number of miRNA expression based on miRBase 21. In addition to the identification of differentially expressed miRNAs from RNA sequencing data, additional novel miRNA candidates were determined with a tool for identifying new miRNA sequences (miRDeep2).

RESULTS

We identified 33 up-regulated miRNAs (fold change ≥2) and 39 potentially new miRNA candidates (miRDeep scores 0-43.6). A manual sequence analysis of the miRNA candidates on the genomic locus of chromosome 1 with provisional IDs of chr1_1913 and chr1_421 was further carried out and rated as promising (chr1_1913) and borderline (chr1_421). Histopathology revealed skip lesions in clinically healthy appearing skin at the tumor margins, which were the cause of seven re-excisions by micrographic controlled surgery to achieve tumor-free margins.

CONCLUSION

miRNA sequencing revealed novel miRNA candidates that need to be further confirmed in functional Dicer knockout studies. Clinically, on the basis of our surgical experience described here, neoadjuvant vismodegib therapy in BCC appears to impede histopathologic evaluations with effects on surgical therapy. Thus, larger studies are necessary, but are not preferable at this time if other options are available.