Targeting oncogenic microRNAs from the miR-371~373 and miR-302/367 clusters in malignant germ cell tumours causes growth inhibition through cell cycle disruption.

BACKGROUND: MiR-371~373 and miR-302/367 cluster over-expression occurs in all malignant germ cell tumours (GCTs), regardless of age (paediatric/adult), site (gonadal/extragonadal), or subtype [seminoma, yolk sac tumour (YST), embryonal carcinoma (EC)]. Six of eight microRNAs from these clusters contain the seed sequence 'AAGUGC', determining mRNA targeting. Here we sought to identify the significance of these observations by targeting these microRNAs functionally. METHODS: We targeted miR-371~373 and/or miR-302/367 clusters in malignant GCT cell lines, using CRISPR-Cas9, gapmer primary miR-302/367 transcript inhibition, and peptide nucleic acid (PNA) or locked nucleic acid (LNA)-DNA inhibition targeting miR-302a-d-3p, and undertook relevant functional assays. RESULTS: MiR-302/367 cluster microRNAs made the largest contribution to AAGUGC seed abundance in malignant GCT cells, regardless of subtype (seminoma/YST/EC). Following the unsuccessful use of CRISPR-Cas9, gapmer, and PNA systems, LNA-DNA-based targeting resulted in growth inhibition in seminoma and YST cells. This was associated with the de-repression of multiple mRNAs targeted by AAGUGC seed-containing microRNAs, with pathway analysis confirming predominant disruption of Rho-GTPase signalling, vesicle organisation/transport, and cell cycle regulation, findings corroborated in clinical samples. Further LNA-DNA inhibitor studies confirmed direct cell cycle effects, with an increase of cells in G0/G1-phase and a decrease in S-phase. CONCLUSION: Targeting of specific miR-371~373 and miR-302/367 microRNAs in malignant GCTs demonstrated their functional significance, with growth inhibition mediated through cell cycle disruption.

Haematological malignancies in sub-Saharan Africa: east Africa as an example for improving care.

Haematological malignancies account for almost 10% of all cancers diagnosed in sub-Saharan Africa, although the exact incidences and treatment outcomes are difficult to discern because population-based cancer registries in the region are still underdeveloped. More research on haematological malignancies in sub-Saharan Africa is required to establish whether these cancers have a natural history similar to those diagnosed in high-income countries, about which more is known. Several factors negatively affect the outcome of haematological malignancies in sub-Saharan Africa, showcasing a need for improved understanding of the clinicobiological profile of these cancers to facilitate prevention, early detection, diagnosis, and appropriate treatment through increased capacity building, infrastructure, community awareness, coordinated resource mobilisation, and collaboration across the world. The east African governments have pooled resources for common investments to tackle non-communicable diseases, developing the East Africa's Centres of Excellence for Skills and Tertiary Education project funded by the African Development Bank, an initiative that could be replicated for the care of haematological malignancies in other countries in sub-Saharan Africa. TRANSLATION: For the French translation of the abstract see Supplementary Materials section.

"Future-Proofing" Blood Processing for Measurement of Circulating miRNAs in Samples from Biobanks and Prospective Clinical Trials.

Background: Quantifying circulating nucleic acids is an important new approach to cancer diagnosis/monitoring.Methods: We compared the suitability of serum versus plasma for measuring miRNAs using qRT-PCR and assessed how preanalytic variables that can affect circulating tumor DNA (ctDNA) quantification in plasma also influence miRNA levels.Results: Across 62 blood-derived specimens, plasma samples in EDTA, Streck-DNA, and Streck-RNA tubes showed significantly higher Ct values for multiple housekeeping miRNAs, compared with serum samples. For the EDTA-plasma tubes, this difference was only seen when including the high-speed centrifugation protocol used to optimize ctDNA extraction. In plasma samples derived from blood stored at room temperature for up to 14 days (conditions that typically apply to samples processed for biobanking), levels of endogenous housekeeping miRNAs gradually increased, in parallel with the hemolysis marker hsa-miR-451a, consistent with release from blood cells/platelets. It was necessary to normalize levels of the housekeeping miRNAs to those of hsa-miR-451a, to obtain the stable values needed for referencing test miRNA levels.Conclusions: Our data indicate that plasma samples prepared for ctDNA extraction are suboptimal for miRNA quantification and require the incorporation of multiple data normalization steps. For prospective studies designed to measure both miRNAs and ctDNA, the most suitable approach would be to obtain both serum (for miRNAs) and plasma (for ctDNA). If only plasma can be collected, we recommend an initial low-speed centrifugation step, followed by aliquoting the supernatant into parallel samples, one for direct miRNA quantification, and the other for a further high-speed centrifugation step to optimize ctDNA retrieval.Impact: These recommendations will help "future-proof" clinical studies in which quantification of circulating miRNAs is a component. Cancer Epidemiol Biomarkers Prev; 27(2); 208-18. ©2017 AACR.