Aberrant expression of alternative isoforms of transcription factors in hepatocellular carcinoma

Optimized Transcriptional Signature for Evaluation of MEK/ERK Pathway Baseline Activity and Long-Term Modulations in Ovarian Cancer

Ovarian cancer is the most aggressive and lethal of all gynecologic malignancies. The high activity of the MEK/ERK signaling pathway is tightly associated with tumor growth, high recurrence rate, and treatment resistance. Several transcriptional signatures were proposed recently for evaluation of MEK/ERK activity in tumor tissue. In the present study, we validated the performance of a robust multi-cancer MPAS 10-gene signature in various experimental models and publicly available sets of ovarian cancer samples. Expression of four MPAS genes (PHLDA1, DUSP4, EPHA2, and SPRY4) displayed reproducible responses to MEK/ERK activity modulations across several experimental models in vitro and in vivo. Levels of PHLDA1, DUSP4, and EPHA2 expression were also significantly associated with baseline levels of MEK/ERK pathway activity in multiple human ovarian cancer cell lines and ovarian cancer patient samples available from the TCGA database. Initial platinum therapy resistance and advanced age at diagnosis were independently associated with poor overall patient survival. Taken together, our results demonstrate that the performance of transcriptional signatures is significantly affected by tissue specificity and aspects of particular experimental models. We therefore propose that gene expression signatures derived from comprehensive multi-cancer studies should be always validated for each cancer type.

How can same-gene mutations promote both cancer and developmental disorders?

The question of how same-gene mutations can drive both cancer and neurodevelopmental disorders has been puzzling. It has also been puzzling why those with neurodevelopmental disorders have a high risk of cancer. Ras, MEK, PI3K, PTEN, and SHP2 are among the oncogenic proteins that can harbor mutations that encode diseases other than cancer. Understanding why some of their mutations can promote cancer, whereas others promote neurodevelopmental diseases, and why even the same mutations may promote both phenotypes, has important clinical ramifications. Here, we review the literature and address these tantalizing questions. We propose that cell type–specific expression of the mutant protein, and of other proteins in the respective pathway, timing of activation (during embryonic development or sporadic emergence), and the absolute number of molecules that the mutations activate, alone or in combination, are pivotal in determining the pathological phenotypes—cancer and (or) developmental disorders.

Splice variants of RAS-translational significance

One of the mechanisms potentially explaining the discrepancy between the number of human genes and the functional complexity of organisms is generating alternative splice variants, an attribute of the vast majority of multi-exon genes. Members of the RAS family, such as NRAS, KRAS and HRAS, all of which are of significant importance in cancer biology, are no exception. The structural and functional differences of these splice variants, particularly if they contain the canonical (and therefore routinely targeted for diagnostic purposes) hot spot mutations, pose a significant challenge for targeted therapies. We must therefore consider whether these alternative splice variants constitute a minor component as originally thought and how therapies targeting the canonical isoforms affect these alternative splice variants and their overall functions.

Unresolved Complexity in the Gene Regulatory Network Underlying EMT

Epithelial to mesenchymal transition (EMT) is the process whereby a polarized epithelial cell ceases to maintain cell-cell contacts, loses expression of characteristic epithelial cell markers, and acquires mesenchymal cell markers and properties such as motility, contractile ability, and invasiveness. A complex process that occurs during development and many disease states, EMT involves a plethora of transcription factors (TFs) and signaling pathways. Whilst great advances have been made in both our understanding of the progressive cell-fate changes during EMT and the gene regulatory networks that drive this process, there are still gaps in our knowledge. Epigenetic modifications are dynamic, chromatin modifying enzymes are vast and varied, transcription factors are pleiotropic, and signaling pathways are multifaceted and rarely act alone. Therefore, it is of great importance that we decipher and understand each intricate step of the process and how these players at different levels crosstalk with each other to successfully orchestrate EMT. A delicate balance and fine-tuned cooperation of gene regulatory mechanisms is required for EMT to occur successfully, and until we resolve the unknowns in this network, we cannot hope to develop effective therapies against diseases that involve aberrant EMT such as cancer. In this review, we focus on data that challenge these unknown entities underlying EMT, starting with EMT stimuli followed by intracellular signaling through to epigenetic mechanisms and chromatin remodeling.

miR-1-3p suppresses proliferation of hepatocellular carcinoma through targeting SOX9

Background

Liver cancer was the fourth leading cause of cancer-related death in 2015. Hepatocellular carcinoma (HCC) is the most common type of liver cancer. miR-1-3p plays important roles in cancer, including prostate, bladder, lung cancer, and colorectal carcinoma. The function of miR-1-3p in HCC remains poorly understood.

Methods

qRT-PCR was performed to detect the miR-1-3p expression in HCC cell lines (HCCLM3, Hep3B, Bel-7404, SMMC-7721) and the normal human hepatic cell line (LO2). HCCLM3 and Bel-7404 cells were transfected with miR-1-3p mimic or scramble control followed by water-soluble tetrazolium salt (WST-1) assay. Western bolt analysis was performed to determine the protein levels. TargetScan7.1 (http://www.targetscan.org/vert_71/) was used to predict the potential targets of miR-1-3p. SRY (sex determining region Y)-box 9 (SOX9), which has been previously shown to play an important role in HCC, was found to be a target of miR-1-3p. Luciferase reporter assay was used to explore the targeting of miR-1-3p on SOX9. For in vivo tumorigenesis assay, HCCLM3 cells with stable overexpression of miR-1-3p or control plasmid were injected subcutaneously into the flank of the SCID mice and animals were monitored for tumor growth.

Results

miR-1-3p was significantly downregulated in HCC cell lines (HCCLM3, Hep3B, Bel-7404, and SMMC-7721) compared to normal human hepatic cell line (LO2). Overexpression of miR-1-3p significantly inhibited the proliferation and induced apoptosis in HCCLM3 and Bel-7474 cells. SOX9 was a direct target of miR-1-3p in HCC cells. Inhibition of SOX9 significantly inhibited the proliferation of HCCLM3 and Bel-7474 cells. In vivo, overexpression of miR-1-3p decreased tumor volume in a xenograft model.

Conclusion

These results highlight the role of miR-1-3p in HCC. Overexpression of miR-1-3P inhibited the proliferation of HCC at least partly due to the regulation of SOX9. miR-1-3p may be a promising therapeutic candidate for HCC.