Mitogen- and stress-activated protein kinases 1 and 2 are required for maximal trefoil factor 1 induction

Sulforaphene suppresses oesophageal cancer growth through mitogen- and stress-activated kinase 2 in a PDX mouse model

BACKGROUND

Although sulforaphene has potential anticancer effects, little is known about its effect on oesophageal squamous cell carcinoma (ESCC) invasiveness.

METHODS

To investigate whether sulforaphene inhibits the growth of oesophageal cancer cells, MTT and anchorage-independent cell growth assays were performed. Global changes in the proteome and phosphoproteome of oesophageal cancer cells after sulforaphene treatment were analysed by mass spectrometry (MS), and the underlying molecular mechanism was further verified by in vivo and in vitro experiments.

RESULTS

Sulforaphene treatment markedly affected proteins that regulate several cellular processes in oesophageal cancer cells, and mitogen- and stress-activated kinase 2 (MSK2) was the main genetic target of sulforaphene in reducing the growth of oesophageal cancer cells. Sulforaphene significantly suppressed ESCC cell proliferation in vitro and reduced the tumour size in an oesophageal patient-derived xenograft (PDX) SCID mouse model. Furthermore, the binding of sulforaphane to MSK2 in vitro was verified using a cellular thermal dhift assay, and the effect of MSK2 knockdown on the ESCC phenotype was observed using a shMSK2 model.

CONCLUSION

The results showed that sulforaphene suppresses ESCC growth in both human oesophageal squamous cells and PDX mouse model by inhibiting MSK2 expression, implicating sulforaphene as a promising candidate for ESCC treatment.

Mitogen- and stress-activated protein kinase (MSK1/2) regulated gene expression in normal and disease states

The mitogen- and stress-activated protein kinases (MSK) are epigenetic modifiers that regulate gene expression in normal and disease cell states. MSK1 and 2 are involved in a chain of signal transduction events bringing signals from the external environment of a cell to specific sites in the genome. MSK1/2 phosphorylate histone H3 at multiple sites, resulting in chromatin remodeling at regulatory elements of target genes and the induction of gene expression. Several transcription factors (RELA of NF-κB and CREB) are also phosphorylated by MSK1/2 and contribute to induction of gene expression. In response to signal transduction pathways, MSK1/2 can stimulate genes involved in cell proliferation, inflammation, innate immunity, neuronal function, and neoplastic transformation. Abrogation of the MSK-involved signaling pathway is among the mechanisms by which pathogenic bacteria subdue the host's innate immunity. Depending on the signal transduction pathways in play and the MSK-targeted genes, MSK may promote or hinder metastasis. Thus, depending on the type of cancer and genes involved, MSK overexpression may be a good or poor prognostic factor. In this review, we focus on mechanisms by which MSK1/2 regulate gene expression, and recent studies on their roles in normal and diseased cells.

Rebelled epigenome: histone H3S10 phosphorylation and H3S10 kinases in cancer biology and therapy

Background

With the discovery that more than half of human cancers harbor mutations in chromatin proteins, deregulation of epigenetic mechanisms has been recognized a hallmark of malignant transformation. Post-translational modifications (PTMs) of histone proteins, as main components of epigenetic regulatory machinery, are also broadly accepted as therapeutic target. Current “epigenetic” therapies target predominantly writers, erasers and readers of histone acetylation and (to a lesser extent) methylation, leaving other types of PTMs largely unexplored. One of them is the phosphorylation of serine 10 on histone H3 (H3S10ph).

Main body

H3S10ph is emerging as an important player in the initiation and propagation of cancer, as it facilitates cellular malignant transformation and participates in fundamental cellular functions. In normal cells this histone mark dictates the hierarchy of additional histone modifications involved in the formation of protein binding scaffolds, transcriptional regulation, blocking repressive epigenetic information and shielding gene regions from heterochromatin spreading. During cell division, this mark is essential for chromosome condensation and segregation. It is also involved in the function of specific DNA–RNA hybrids, called R-loops, which modulate transcription and facilitate chromosomal instability. Increase in H3S10ph is observed in numerous cancer types and its abundance has been associated with inferior prognosis. Many H3S10-kinases, including MSK1/2, PIM1, CDK8 and AURORA kinases, have been long considered targets in cancer therapy. However, since these proteins also participate in other critical processes, including signal transduction, apoptotic signaling, metabolic fitness and transcription, their chromatin functions are often neglected.

Conclusions

H3S10ph and enzymes responsible for deposition of this histone modification are important for chromatin activity and oncogenesis. Epigenetic-drugs targeting this axis of modifications, potentially in combination with conventional or targeted therapy, provide a promising angle in search for knowledge-driven therapeutic strategies in oncology.

The nuclear phosphoinositide response to stress

Accumulating evidence reveals that nuclear phosphoinositides (PIs) serve as central signaling hubs that control a multitude of nuclear processes by regulating the activity of nuclear proteins. In response to cellular stressors, PIs accumulate in the nucleus and multiple PI isomers are synthesized by the actions of PI-metabolizing enzymes, kinases, phosphatases and phospholipases. By directly interacting with effector proteins, phosphoinositide signals transduce changes in cellular functions. Here we describe nuclear phosphoinositide signaling in multiple sub-nuclear compartments and summarize the literature that demonstrates roles for specific kinases, phosphatases, and phospholipases in the orchestration of nuclear phosphoinositide signaling in response to cellular stress. Additionally, we discuss the specific PI-protein complexes through which these lipids execute their functions by regulating the configuration, stability, and transcription activity of their effector proteins. Overall, our review provides a detailed landscape of the current understanding of the nuclear PI-protein interactome and its role in shaping the coordinated response to cellular stress.

MSK2 promotes proliferation and tumor formation in squamous cervical cancer via PAX8/RB-E2F1/cyclin A2 axis

Patients with cervical cancer have abnormal cell proliferation and invasion after many years of latency. However, the precise mechanisms remain unclear. Mitogen- and stress-activated kinase 2 (MSK2) is a serine/threonine kinase which displays a phenotype that promotes tumor growth and metastasis in many different types of tumors. The aim of the present study was to determine the effects of MSK2 on the proliferation of cervical cancer cells and elucidate the signaling pathways through which MSK2 exerts its effects in the pathogenesis of squamous cell carcinoma (SCC). Our results confirmed that MSK2 expression was significantly upregulated in cervical cancer cells both in vivo and in vitro. We further found that the expression patterns of paired-box gene 8 (PAX8) and MSK2 were positively correlated in cervical cancer specimens. Moreover, MSK2 knockdown inhibited the phosphorylation of PAX8 and retinoblastoma protein (RB), and suppressed the sequential expressions of cell proliferation factors E2F1 and cyclin A2, resulting in the inhibition of SCC cell proliferation and tumor formation. Thus, this study demonstrates that MSK2 has oncogenic effects in the formation and development of SCC via the PAX8/RB-E2F1/cyclin A2 axis.

Mechanisms of Antiulcer Effect of an Active Ingredient Group of Modified Xiao Chaihu Decoction

The present study aimed to investigate the antiulcer activities and mechanisms of action of an active ingredient group (AIG) of Modified Xiao Chaihu Decoction (MXCD). The gastroprotective action of the AIG was studied in ethanol-induced, pylorus ligature-induced, and acetic acid-induced in vivo gastric ulcer models. The enzyme-linked immunoadsorbent assay (tumor necrosis factor-α (TNF-α), prostaglandin E₂ (PGE₂), and epidermal growth factor (EGF)), nitrate reductase assay (nitric oxide (NO)), western blot analysis (Bax, Bcl-2, cleaved-caspase-3, and cleaved-PARP (poly (ADP-Ribose) polymerase)), histological analysis (HE), and immunohistochemical analysis (HSP-70, p-AKT, and PCNA) were used to evaluate the anti-inflammatory, antiapoptotic, and healing properties of AIG. Numerous mechanisms are involved in the antiulcer activity of AIG, including the increase of PGE₂, NO, and EGF content and a reduction in TNF-α levels. The upregulation of HSP-70, p-AKT, and PCNA seems to be directly linked to the healing effect of AIG. Bax, Bcl-2, cleaved-caspase-3, and cleaved-PARP also play a key role in this process. The AIG exerted gastroprotective effects by reducing antisecretory, anti-inflammatory, and antiapoptotic mechanisms. In addition, it promotes cell proliferation. Therefore, activation of the PI3K/AKT signaling pathway may play an important role in cell proliferation.

High nuclear MSK1 is associated with longer survival in breast cancer patients

Purpose

Mitogen- and stress-activated kinases (MSKs) are important substrates of the mitogen-activated protein kinase (MAPK)-activated protein kinase family. MSK1 and MSK2 are both nuclear serine/threonine protein kinases, with MSK1 being suggested to potentially play a role in breast cancer cell proliferation, cell cycle progression, cell migration, invasion and tumour growth. The aim of the current study was to assess MSK1 protein expression in breast cancer tumour specimens, evaluating its prognostic significance.

Methods

A large cohort of 1902 early stage invasive breast cancer patients was used to explore the expression of MSK1. Protein expression was examined using standard immunohistochemistry on tissue microarrays.

Results

Low MSK1 protein expression was associated with younger age (P = 0.004), higher tumour grade (P < 0.001), higher Nottingham Prognostic Index scores (P = 0.007), negative ER (P < 0.001) and PR (P < 0.001) status, and with triple-negative (P < 0.001) and basal-like (P < 0.001) phenotypes. Low MSK1 protein expression was significantly associated with shorter time to distant metastasis (P < 0.001), and recurrence (P = 0.013) and early death due to breast cancer (P = 0.01). This association between high MSK1 expression and improved breast cancer-specific survival was observed in the whole cohort (P = 0.009) and in the HER2-negative and non-basal like tumours (P = 0.006 and P = 0.024, respectively). Multivariate analysis including other prognostic variables indicated that MSK1 is not an independent marker of outcome.

Conclusions

High MSK1 is associated with improved breast cancer-specific survival in early stage invasive breast cancer patients, and has additional prognostic value in HER2-negative and non-basal like disease. Although not an independent marker of outcome, we believe such findings and significant associations with well-established negative prognostic factors (age, grade, Nottingham Prognostic Index, hormone receptor status, time to distant metastasis, recurrence and triple-negative/basal-like status) warrant further examination and validation in independent patient cohorts.

Mitogen-induced distinct epialleles are phosphorylated at either H3S10 or H3S28, depending on H3K27 acetylation

Stimulation of the MAPK pathway results in mitogen- and stress-activated protein kinase 1/2 (MSK1/2)-catalyzed phosphorylation of histone H3 at serine 10 or 28 and expression of immediate-early (IE) genes. In 10T1/2 mouse fibroblasts, phosphorylation of H3S10 and H3S28 occurs on different H3 molecules and in different nuclear regions. Similarly, we show that mitogen-induced H3S10 and H3S28 phosphorylation occurs in separate pools in human primary fibroblasts. High-resolution imaging studies on both cell types reveal that H3S10 and H3S28 phosphorylation events can be induced in a single cell but on different alleles, giving rise to H3S10ph and H3S28ph epialleles. Coimmunoprecipitation and inhibition studies demonstrate that CBP/p300-mediated H3K27 acetylation is required for MSK1/2 to phosphorylate S28. Although the K9ac and S10ph marks coexist on H3, S10 phosphorylation is not dependent on K9 acetylation by PCAF. We propose that random targeting of H3S10 or H3S28 results from the stochastic acetylation of H3 by CBP/p300 or PCAF, a process comparable to transcriptional bursting causing temporary allelic imbalance. In 10T1/2 cells expressing Jun, at least two of three alleles per cell were induced, a sign of high expression level. The redundant roles of H3S10ph and H3S28ph might enable rapid and efficient IE gene induction.

Gastric Proteins MUC5AC and TFF1 as Potential Diagnostic Markers of Colonic Sessile Serrated Adenomas/Polyps

OBJECTIVES

A subset of colon cancers originates from sessile serrated adenomas/polyps (SSA/Ps). Our goal was to identify markers for SSA/Ps that could aid in distinguishing them from hyperplastic polyps (HPs).

METHODS

We performed immunostaining for gastric proteins MUC5AC and TFF1 in formalin-fixed, paraffin-embedded (FFPE) samples of HPs (n = 47), SSA/Ps (n = 37), and normal colon (n = 30).

RESULTS

Control mucosa expressed only trace amounts of MUC5AC and TFF1. HPs exhibited an 11.3- and 11.4-fold increase in MUC5AC and TFF1 expression confined to the upper segments of the crypts near the luminal surface of the polyps. SSA/Ps displayed on average 1.6-fold (MUC5AC, P  < .008) and 1.4-fold (TFF1, P  < .03) higher signal intensity for these markers than HPs, with a dramatic coexpression of MUC5AC and TFF1 typically occupying the entire length of the crypt. Immunoperoxidase results were similar to immunofluorescence staining for both MUC5AC and TFF1.

CONCLUSIONS

Our results suggest that the analysis of expression of MUC5AC and TFF1 may be useful for differentiating SSA/Ps from HPs. We also suggest the possibility that crypt morphology may be at least partly due to overproduction of highly viscous gastric mucins and that these proteins may play a role in the serrated pathway to colon carcinogenesis.

The role of the 14-3-3 protein family in health, disease, and drug development

14-3-3 proteins regulate intracellular signaling pathways, such as signal transduction, protein trafficking, cell cycle, and apoptosis. In addition to the ubiquitous roles of 14-3-3 isoforms, unique tissue-specific functions are also described for each isoform. Owing to their role in regulating cell cycle, protein trafficking, and steroidogenesis, 14-3-3 proteins are prevalent in human diseases, such as cancer, neurodegeneration, and reproductive disorders, and, therefore, serve as valuable drug targets. In this review, we summarize the role of 14-3-3 proteins in normal and disease states, with a focus on 14-3-3γ and ɛ. We also discuss drug compounds targeting 14-3-3 proteins and their potential therapeutic uses.

The cyclic AMP response element-binding protein (CREB) mediates smooth muscle cell proliferation in response to angiotensin II

The cAMP response element-binding protein (CREB) is a transcription factor that mediates the cellular response to metabolic and mitogenic signals. Whether CREB contributes to vascular function has received little attention, especially in relation to the processes associated with atherosclerotic disease progression and restenosis. This study examined the involvement of CREB in the mitogenic actions of angiotensin II (AngII), a growth factor that promotes neointimal hyperplasia in response to vascular injury. Treatments were performed on quiescent vascular smooth muscle cells (VSMCs) obtained from a porcine explant model. Organ culture was performed on porcine hearts subjected to angioplasty ex vivo. Stimulation of VSMCs with AngII resulted in transient CREB phosphorylation. Proliferation of smooth muscle cells in response to AngII was reduced by 90 % after infection with adenovirus expressing dominant-negative killer CREB (kCREB) mutant. Likewise, expression of kCREB prevented angioplasty-induced neointimal hyperplasia. AngII-induced CREB phosphorylation was independent of cAMP activation. Examination of putative CREB kinases revealed that MSK was responsible for phosphorylating CREB. In addition, inhibition of PKC revealed that this kinase operates upstream and activates MSK. These results indicate that activation of CREB via PKC and MSK is essential for SMC proliferation in response to AngII.