MicroRNA-23b Plays a Tumor-Suppressive Role in Cutaneous Squamous Cell Carcinoma and Targets Ras-Related Protein RRAS2.

Cutaneous squamous cell carcinoma (cSCC) is one of the most common types of cancer with metastatic potential. MicroRNAs regulate gene expression at the post-transcriptional level. In this study, we report that miR-23b is downregulated in cSCCs and in actinic keratosis and that its expression is regulated by the MAPK signaling pathway. We show that miR-23b suppresses the expression of a gene network associated with key oncogenic pathways and that the miR-23b-gene signature is enriched in human cSCCs. miR-23b decreased the expression of FGF2 both at mRNA and protein levels and impaired the angiogenesis-inducing ability of cSCC cells. miR23b overexpression suppressed the capacity of cSCC cells to form colonies and spheroids, whereas the CRISPR/Cas9-mediated deletion of MIR23B resulted in increased colony and tumor sphere formation in vitro. In accordance with this, miR-23b-overexpressing cSCC cells formed significantly smaller tumors upon injection into immunocompromised mice with decreased cell proliferation and angiogenesis. Mechanistically, we verify RRAS2 as a direct target of miR-23b in cSCC. We show that RRAS2 is overexpressed in cSCC and that interference with its expression impairs angiogenesis and colony and tumorsphere formation. Taken together, our results suggest that miR-23b acts in a tumor-suppressive manner in cSCC, and its expression is decreased during squamous carcinogenesis.

"Cells-to-cDNA on Chip": Phenotypic Assessment and Gene Expression Analysis from Live Cells in Nanoliter Volumes Using Droplet Microarrays.

In vitro cell-based experiments are particularly important in fundamental biological research. Microscopy-based readouts to identify cellular changes in response to various stimuli are a popular choice, but gene expression analysis is essential to delineate the underlying molecular dynamics in cells. However, cell-based experiments often suffer from interexperimental variation, especially while using different readout methods. Therefore, establishment of platforms that allow for cell screening, along with parallel investigations of morphological features, as well as gene expression levels, is crucial. The droplet microarray (DMA) platform enables cell screening in hundreds of nanoliter droplets. In this study, a "Cells-to-cDNA on Chip" method is developed enabling on-chip mRNA isolation from live cells and conversion to cDNA in individual droplets of 200 nL. This novel method works efficiently to obtain cDNA from different cell numbers, down to single cell per droplet. This is the first established miniaturized on-chip strategy that enables the entire course of cell screening, phenotypic microscopy-based assessments along with mRNA isolation and its conversion to cDNA for gene expression analysis by real-time PCR on an open DMA platform. The principle demonstrated in this study sets a beginning for myriad of possible applications to obtain detailed information about the molecular dynamics in cultured cells.

SOX2 in development and cancer biology.

The transcription factor SOX2 is essential for embryonic development and plays a crucial role in maintaining the stemness of embryonic cells and various adult stem cell populations. On the other hand, dysregulation of SOX2 expression is associated with a multitude of cancer types and it has been shown that SOX2 positively affects cancer cell traits such as the capacity to proliferate, migrate, invade and metastasize. Moreover, there is growing evidence that SOX2 mediates resistance towards established cancer therapies and that it is expressed in cancer stem cells. These findings indicate that studying the role of SOX2 in the context of cancer progression could lead to the development of new therapeutic options. In this review, the current knowledge about the role of SOX2 in development, maintenance of stemness, cancer progression and the resistance towards cancer therapies is summarized.