miR clusters target cellular functional complexes by defining their degree of regulatory freedom.

Using the two paralog miR-23∼27∼24 clusters as an example and combining experimental and clinical data in a systematical approach to microRNA (miR) function and dysregulation, a complex picture of their roles in cancer is drawn. Various findings appear to be contradictory to a larger extent and cannot be fully explained by the classical regulatory network models and feedback loops that are mainly considered by one-to-one regulatory interactions of the involved molecules. Here, we propose an extended model of the regulatory role of miRs that, at least, supplements the usually considered single/oligo-target regulation of certain miRs. The cellular availability of the participating miR members in this model reflects an upper hierarchy level of intracellular and extracellular environmental influences, such as neighboring cells, soluble factors, hypoxia, chemotherapeutic drugs, and irradiation, among others. The novel model is based on the understanding of cellular functional complexes, such as for apoptosis, migration, and proliferation. These complexes consist of many regulatory components that can be targeted by miR cluster members to a different extent but may affect the functional complex in different ways. We propose that the final miR-related effect is a result of the possible degree of regulatory freedom provided by the miR effects on the whole functional complex structure. This degree of regulatory freedom defines to which extent the cellular functional complex can react in response to regulatory triggers, also understood as sensitization (more regulatory response options) or de-sensitization (less regulatory response options) of the system rather than single molecules.

Correction: Flammang et al. Tumor-Suppressive miR-192-5p Has Prognostic Value in Pancreatic Ductal Adenocarcinoma. Cancers 2020, 12, 1693.

In the original publication [...].

Dysregulation of miRNA Expression in Cancer Associated Fibroblasts (CAFs) and Its Consequences on the Tumor Microenvironment.

The tumor microenvironment, including cancer-associated fibroblasts (CAF), has developed as an important target for understanding tumor progression, clinical prognosis and treatment responses of cancer. Cancer cells appear to transform normal fibroblasts (NF) into CAFs involving direct cell-cell communication and epigenetic regulations. This review summarizes the current understanding on miR involvement in cancer cell-tumor environment/stroma communication, transformation of NFs into CAFs, their involved targets and signaling pathways in these interactions; and clinical relevance of CAF-related miR expression profiles. There is evidence that miRs have very similar roles in activating hepatic (HSC) and pancreatic stellate cells (PSC) as part of precancerous fibrotic diseases. In summary, deregulated miRs affect various intracellular functional complexes, such as transcriptional factors, extracellular matrix, cytoskeleton, EMT/MET regulation, soluble factors, tyrosine kinase and G-protein signaling, apoptosis and cell cycle & differentiation, but also formation and composition of the extracellular microenvironment. These processes result in the clinical appearance of desmoplasia involving CAFs and fibrosis characterized by deregulated stellate cells. In addition, modulated release of soluble factors can act as (auto)activating feedback loop for transition of NFs into their pathological counterparts. Furthermore, epigenetic communication between CAFs and cancer cells may confer to cancer specific functional readouts and transition of NF. MiR related epigenetic regulation with many similarities should be considered as key factor in development of cancer and fibrosis specific environment.

ARTIK-52 induces replication-dependent DNA damage and p53 activation exclusively in cells of prostate and breast cancer origin.

The realization, that the androgen receptor (AR) is essential for prostate cancer (PC) even after relapse following androgen deprivation therapy motivated the search for novel types of AR inhibitors. We proposed that targeting AR expression versus its function would work in cells having either wild type or mutant AR as well as be independent of androgen synthesis pathways. Previously, using a phenotypic screen in androgen-independent PC cells we identified a small molecule inhibitor of AR, ARTIK-52. Treatment with ARTIK-52 caused the loss of AR protein and death of AR-positive, but not AR-negative, PC cells. Here we present data that ARTIK-52 induces degradation of AR mRNA through a mechanism that we were unable to establish. However, we found that ARTIK-52 is toxic to breast cancer (BC) cells expressing AR, although they were not sensitive to AR knockdown, suggesting an AR-independent mechanism of toxicity. Using different approaches we detected that ARTIK-52 induces replication-dependent double strand DNA breaks exclusively in cancer cells of prostate and breast origin, while not causing DNA damage, or any toxicity, in normal cells, as well as in non-PC and non-BC tumor cells, independent of their proliferation status. This amazing specificity, combined with such a basic mechanism of toxicity, makes ARTIK-52 a potentially useful tool to discover novel attractive targets for the treatment of BC and PC. Thus, phenotypic screening allowed us to identify a compound, whose properties cannot be predicted based on existing knowledge and moreover, uncover a barely known link between AR and DNA damage response in PC and BC epithelial cells.

MicroRNA Profiling Implies New Markers of Gemcitabine Chemoresistance in Mutant p53 Pancreatic Ductal Adenocarcinoma.

BACKGROUND: No reliable predictors of susceptibility to gemcitabine chemotherapy exist in pancreatic ductal adenocarcinoma (PDAC). MicroRNAs (miR) are epigenetic gene regulators with tumorsuppressive or oncogenic roles in various carcinomas. This study assesses chemoresistant PDAC for its specific miR expression pattern. METHODS: Gemcitabine-resistant variants of two mutant p53 human PDAC cell lines were established. Survival rates were analyzed by cytotoxicity and apoptosis assays. Expression of 1733 human miRs was investigated by microarray and validated by qRT-PCR. After in-silico analysis of specific target genes and proteins of dysregulated miRs, expression of MRP-1, Bcl-2, mutant p53, and CDK1 was quantified by Western blot. RESULTS: Both established PDAC clones showed a significant resistance to gemcitabine (p<0.02) with low apoptosis rate (p<0.001) vs. parental cells. MiR-screening revealed significantly upregulated (miR-21, miR-99a, miR-100, miR-125b, miR-138, miR-210) and downregulated miRs (miR-31*, miR-330, miR-378) in chemoresistant PDAC (p<0.05). Bioinformatic analysis suggested involvement of these miRs in pathways controlling cell death and cycle. MRP-1 (p<0.02) and Bcl-2 (p<0.003) were significantly overexpressed in both resistant cell clones and mutant p53 (p = 0.023) in one clone. CONCLUSION: Consistent miR expression profiles, in part regulated by mutant TP53 gene, were identified in gemcitabine-resistant PDAC with significant MRP-1 and Bcl-2 overexpression. These results provide a basis for further elucidation of chemoresistance mechanisms and therapeutic approaches to overcome chemoresistance in PDAC.

Mountant-induced loss of Shorr-stained blue sperm tails.

It has been reported that Shorr staining provides additional morphological information on the motility of spermatozoa in semen, by distinguishing between red and blue flagella. With our routine methods (involving mounting slides) we were unable to confirm these observations. The presence of both red- and blue-coloured sperm tails in Shorr-stained semen smears was apparent, however, if slides were unmounted. Only a very weak association between blue flagellar staining and immotility was observed. Stating whether a mountant was used should be reported.

Dimensions of human ejaculated spermatozoa in Papanicolaou-stained seminal and swim-up smears obtained from the Integrated Semen Analysis System (ISAS(®)).

Objective measurements are required for computer-aided sperm morphometric analysis (CASMA) machines to distinguish normal from abnormal sperm heads. The morphometric characteristics of spermatozoa in 72 samples of semen and of spermatozoa from 72 other semen samples after swim-up were quantified by the semi-automated Integrated Sperm Analysis System (ISAS) computer-aided system, which measured the sperm head parameters length (L), width (W), area (A), perimeter (P), acrosomal area (Ac), and the derived values L/W and P/A. For each man a homogeneous population of distributions characterized seminal spermatozoa (7 942 cells: median values L 4.4 µm, W 2.8 µm, A 9.8 µm(2), P 12.5 µm, Ac 47.5%, L/W 1.57, P/A 1.27), and there was no significant difference in within- and among-individual variation. Different men could have spermatozoa of significantly different dimensions. Head dimensions for swim-up spermatozoa from different men (4 812 cells) were similar to those in semen, differing only by 2%-5%. The values of L, W and L/W fell within the limits given by the World Health Organization (WHO). Although these samples were not biologically matched, linear mixed-effects statistical analyses permitted valid comparison of the groups. A subpopulation of 404 spermatozoa considered to fit the stringent criteria of WHO 'normal' seminal spermatozoa from both semen and swim-up were characterized by median values (and 95% confidence intervals) of L, 4.3 µm (3.8-4.9), W, 2.9 µm (2.6-3.3), A, 10.2 µm(2) (8.5-12.2), P, 12.4 µm (11.3-13.9), Ac, 49% (36-60), L/W, 1.49 (1.32-1.67) and P/A, 1.22 (1.11-1.35). These median values fall within the 95th centile confidence limits given by WHO, but the confidence intervals for L and W were larger. Although these differences in head dimensions among men and after swim-up could be detected by CASMA, the small differences make it unlikely that technicians would be able to distinguish them. The values could be used as default sperm head values for the CASMA machine used here.