Alternative RNA splicing provides cells with transcriptomic and proteomic diversity by adding another layer of regulation to gene expression. Accumulating evidence has revealed that defects in alternative splicing contribute to a variety of features of cancer development, including the modulation of cancer heterogeneity, evasion of apoptosis of cancer cells, rewiring cancer metabolism and facilitating cancer metastasis via fine‑tuning the epithelial‑to‑mesenchymal transition process. In this review, well‑known aberrant alternative splicing events associated with multiple aspects of cancer progression were presented based on available data obtained from an extensive literature search used to construct splicing regulatory networks for each of these events. The study aims to provide a more comprehensive understanding of cancer‑associated splicing networks and more precise guidance for targeting these events for cancer treatment.

Differential usage of Kat3 coactivators, CBP and p300, by β-catenin is a fundamental regulatory mechanism in stem cell maintenance and initiation of differentiation and repair. Based upon our earlier pharmacologic studies, p300 serine 89 (S89) is critical for controlling differential coactivator usage by β-catenin via post-translational phosphorylation in stem/progenitor populations, and appears to be a target for a number of kinase cascades. To further investigate mechanisms of signal integration effected by this domain, we generated p300 S89A knock-in mice. We show that S89A mice are extremely sensitive to intestinal insult resulting in colitis, which is known to significantly increase the risk of developing colorectal cancer. We demonstrate cell intrinsic differences, and microbiome compositional differences and differential immune responses, in intestine of S89A versus wild type mice. Genomic and proteomic analyses reveal pathway differences, including lipid metabolism, oxidative stress response, mitochondrial function and oxidative phosphorylation. The diverse effects on fundamental processes including epithelial differentiation, metabolism, immune response and microbiome colonization, all brought about by a single amino acid modification S89A, highlights the critical role of this region in p300 as a signaling nexus and the rationale for conservation of this residue and surrounding region for hundreds of million years of vertebrate evolution.

The integration of cellular status with metabolism is critically important and the coupling of energy production and cellular function is highly evolutionarily conserved. This has been demonstrated in stem cell biology, organismal, cellular and tissue differentiation and in immune cell biology. However, a molecular mechanism delineating how cells coordinate and couple metabolism with transcription as they navigate quiescence, growth, proliferation, differentiation and migration remains in its infancy. The extreme N-termini of the Kat3 coactivator family members, CBP and p300, by far the least homologous regions with only 66% identity, interact with members of the nuclear receptor family, interferon activated Stat1 and transcriptionally competent β-catenin, a critical component of the Wnt signaling pathway. We now wish to report based on multiomic and functional investigations, utilizing p300 knockdown, N-terminal p300 edited and p300 S89A edited cell lines and p300 S89A knockin mice, that the N-termini of the Kat3 coactivators provide a highly evolutionarily conserved hub to integrate multiple signaling cascades to coordinate cellular metabolism with the regulation of cellular status and function.

The therapeutic potential of targeting the β-catenin/CBP interaction has been demonstrated in a variety of preclinical tumor models with a small molecule inhibitor, ICG-001, characterized as a β-catenin/CBP antagonist. Despite the high binding specificity of ICG-001 for the N-terminus of CBP, this β-catenin/CBP antagonist exhibits pleiotropic effects. Our recent studies found global changes in three-dimensional (3D) chromatin architecture in response to disruption of the β-catenin/CBP interaction in pancreatic cancer cells. However, an understanding of how the functional crosstalk between the antagonist and the β-catenin/CBP interaction affects changes in 3D chromatin architecture and, thereby, gene expression and downstream effects remains to be elucidated. Here, we perform Hi-C analyses on canonical and patient-derived pancreatic cancer cells before and after treatment with ICG-001. In addition to global alteration of 3D chromatin domains, we unexpectedly identify insulin signaling genes enriched in the altered chromatin domains. We further demonstrate that the chromatin loops associated with insulin signaling genes are significantly weakened after ICG-001 treatment. We finally elicit the deletion of a looping of IRS1—a key insulin signaling gene—significantly impeding pancreatic cancer cell growth, indicating that looping-mediated insulin signaling might act as an oncogenic pathway to promote pancreatic cancer progression. Our work shows that targeting aberrant insulin chromatin looping in pancreatic cancer might provide a therapeutic benefit.

Epithelial to mesenchymal transition (EMT) has been shown to play an essential role in the early stages of cancer cell invasion and metastasis. Inducible EMT models can initiate EMT in a controlled manner, thereby providing the opportunity to determine whether a cancer-associated gene influences cancer metastasis by triggering EMT. Moreover, different inducible EMT models enable the investigation of specific mechanisms of EMT modulation by various genes, facilitating a more precise understanding of how these genes influence cancer metastasis through the induction of EMT. Unfortunately, current inducible EMT models still present unmet needs. Therefore, we aimed to establish an inducible EMT model in MCF10A cells, a spontaneously immortalized human fibrocystic mammary cell line, by manipulating the expression of mouse Twist1 (mTwist1). In this study, we first compared the EMT induction capacity between human TWIST1 (hTWIST1) and mTwist1, and selected mTwist1 for further investigation. By monitoring the changes in epithelial and mesenchymal markers at different induction time points, we examined the EMT process in both polyclonal and monoclonal MCF10A cells that express doxycycline (DOX)-inducible mTwist1. Furthermore, our results showed that doxycycline-induced mTwist1 expression triggered EMT at a similar rate to TGFβ1-induced EMT in MCF10A cells. Additionally, this process was reversible upon DOX withdrawal. Thus, we have established a robust inducible EMT model in MCF10A cells, which can be used to further study cancer metastasis-driving genes.