Survivin is a guardian of the intestinal stem cell niche and its expression is regulated by TGF-β

Survivin in lung cancer: a potential target for therapy and prevention-a narrative review

Background and Objective

A versatile biomarker, survivin, is highly expressed in proliferating cells of multiple cancers in humans and animals. It is an apoptosis-regulating protein, engaging in a cascade of reactions that involve several other genes and protein interactions. Currently, researchers are investigating its therapeutic potential due to the evidence linking its overexpression to advanced-stage lung cancer. This review is centered around examining survivin-related molecular mechanisms and its therapeutic role specifically in lung cancer. Our objective is to discuss the role of survivin in prognosis and treatment response, shedding light on immune-targeted therapies, as well as outlining future directions for survivin-based vaccines in lung cancer.

Methods

The PubMed database and the United States National Library of Medicine search engine at the National Institutes of Health were searched on 24 August 2023 to identify published research studies. Searching "((((((airway [Title/Abstract]) OR (lung [Title/Abstract])) OR (pulm[Title/Abstract])) OR (bronch[Title/Abstract])) OR (nslc[Title/Abstract])) AND (((cancer[Title/Abstract]) OR (carcino[Title/Abstract])) OR (oncol[Title/Abstract]))) AND (survivin[Title/Abstract])" gave 728 results. After screening the title and abstracts and excluding the review articles 168 titles were shortlisted and full text studied. The discussions are added to relevant sections.

Key Content and Findings

Survivin is a cell cycle-dependent, inhibitor of apoptosis protein that contributes to carcinogenesis, tumor vascularization, metastasis, and treatment resistance. Several treatments that impact survivin either directly or indirectly have been reported as effective in treating lung cancer. Immunity-based therapy, a novel approach known for its targeted nature and minimal side effects, is currently under investigation for lung cancer treatment. Emerging survivin-centered vaccines exhibit promising attributes in terms of safety, effectiveness, and ability to stimulate an immune response. These factors point towards a significant potential for advancing the future of lung cancer prevention and enhancing overall survival rates.

Conclusions

Nuclear survivin is a potential biomarker for advanced non-small cell lung cancer. It plays a role in determining drug responsiveness and is found to be significantly elevated in cases of resistance to chemotherapy. Multiple compounds and immunization strategies have been identified to impact lung cancer cells; however, they are currently in the early stages of phase I or phase II clinical trials. The substantial promise of survivin-based immunogenicity-focused treatments warrants in-depth investigation and exploration.

Claudin-2 protects against colitis-associated cancer by promoting colitis-associated mucosal healing

Patients with inflammatory bowel disease (IBD) are susceptible to colitis-associated cancer (CAC). Chronic inflammation promotes the risk for CAC. In contrast, mucosal healing predicts improved prognosis in IBD and reduced risk of CAC. However, the molecular integration among colitis, mucosal healing, and CAC remains poorly understood. Claudin-2 (CLDN2) expression is upregulated in IBD; however, its role in CAC is not known. The current study was undertaken to examine the role for CLDN2 in CAC. The AOM/DSS-induced CAC model was used with WT and CLDN2-modified mice. High-throughput expression analyses, murine models of colitis/recovery, chronic colitis, ex vivo crypt culture, and pharmacological manipulations were employed in order to increase our mechanistic understanding. The Cldn2KO mice showed significant inhibition of CAC despite severe colitis compared with WT littermates. Cldn2 loss also resulted in impaired recovery from colitis and increased injury when mice were subjected to intestinal injury by other methods. Mechanistic studies demonstrated a possibly novel role of CLDN2 in promotion of mucosal healing downstream of EGFR signaling and by regulation of Survivin expression. An upregulated CLDN2 expression protected from CAC and associated positively with crypt regeneration and Survivin expression in patients with IBD. We demonstrate a potentially novel role of CLDN2 in promotion of mucosal healing in patients with IBD and thus regulation of vulnerability to colitis severity and CAC, which can be exploited for improved clinical management.

Modulation of stem cell fate in intestinal homeostasis, injury and repair

The mammalian intestinal epithelium constitutes the largest barrier against the external environment and makes flexible responses to various types of stimuli. Epithelial cells are fast-renewed to counteract constant damage and disrupted barrier function to maintain their integrity. The homeostatic repair and regeneration of the intestinal epithelium are governed by the Lgr5⁺ intestinal stem cells (ISCs) located at the base of crypts, which fuel rapid renewal and give rise to the different epithelial cell types. Protracted biological and physicochemical stress may challenge epithelial integrity and the function of ISCs. The field of ISCs is thus of interest for complete mucosal healing, given its relevance to diseases of intestinal injury and inflammation such as inflammatory bowel diseases. Here, we review the current understanding of the signals and mechanisms that control homeostasis and regeneration of the intestinal epithelium. We focus on recent insights into the intrinsic and extrinsic elements involved in the process of intestinal homeostasis, injury, and repair, which fine-tune the balance between self-renewal and cell fate specification in ISCs. Deciphering the regulatory machinery that modulates stem cell fate would aid in the development of novel therapeutics that facilitate mucosal healing and restore epithelial barrier function.

Survivin Small Molecules Inhibitors: Recent Advances and Challenges

Survivin, as a member of the inhibitor of apoptosis proteins (IAPs) family, acts as a suppressor of apoptosis and plays a central role in cell division. Survivin has been considered as an important cancer drug target because it is highly expressed in many types of human cancers, while it is effectively absent from terminally differentiated normal tissues. Moreover, survivin is involved in tumor cell resistance to chemotherapy and radiation. Preclinically, downregulation of survivin expression or function reduced tumor growth induced apoptosis and sensitized tumor cells to radiation and chemotherapy in different human tumor models. This review highlights the role of survivin in promoting cellular proliferation and inhibiting apoptosis and summarizes the recent advances in and challenges of developing small-molecule survivin inhibitors.

Non-Canonical Programmed Cell Death in Colon Cancer

Simple Summary

Non-canonical PCD is an important player in colon cancer cell suicide. It influences colon cancer in many ways, such as through tumorigenesis, treatment, and prognosis. In this review, we present the mechanism, application, and prospect of different types of non-canonical PCD in colon cancer.

Abstract

Programmed cell death (PCD) is an evolutionarily conserved process of cell suicide that is regulated by various genes and the interaction of multiple signal pathways. Non-canonical programmed cell death (PCD) represents different signaling excluding apoptosis. Colon cancer is the third most incident and the fourth most mortal worldwide. Multiple factors such as alcohol, obesity, and genetic and epigenetic alternations contribute to the carcinogenesis of colon cancer. In recent years, emerging evidence has suggested that diverse types of non-canonical programmed cell death are involved in the initiation and development of colon cancer, including mitotic catastrophe, ferroptosis, pyroptosis, necroptosis, parthanatos, oxeiptosis, NETosis, PANoptosis, and entosis. In this review, we summarized the association of different types of non-canonical PCD with tumorigenesis, progression, prevention, treatments, and prognosis of colon cancer. In addition, the prospect of drug-resistant colon cancer therapy related to non-canonical PCD, and the interaction between different types of non-canonical PCD, was systemically reviewed.

Investigation of Colonic Regeneration via Precise Damage Application Using Femtosecond Laser-Based Nanosurgery

Organoids represent the cellular composition of natural tissue. So called colonoids, organoids derived from colon tissue, are a good model for understanding regeneration. However, next to the cellular composition, the surrounding matrix, the cell-cell interactions, and environmental factors have to be considered. This requires new approaches for the manipulation of a colonoid. Of key interest is the precise application of localized damage and the following cellular reaction. We have established multiphoton imaging in combination with femtosecond laser-based cellular nanosurgery in colonoids to ablate single cells in the colonoids' crypts, the proliferative zones, and the differentiated zones. We observed that half of the colonoids recovered within six hours after manipulation. An invagination of the damaged cell and closing of the structure was observed. In about a third of the cases of targeted crypt damage, it caused a stop in crypt proliferation. In the majority of colonoids ablated in the crypt, the damage led to an increase in Wnt signalling, indicated via a fluorescent lentiviral biosensor. qRT-PCR analysis showed increased expression of various proliferation and Wnt-associated genes in response to damage. Our new model of probing colonoid regeneration paves the way to better understand organoid dynamics on a single cell level.

Sox9, Hopx, and survivin and tuft cell marker DCLK1 expression in normal canine intestine and in intestinal adenoma and adenocarcinoma

Self-renewal of the intestinal epithelium originates from stem cells located at the crypt base. Upregulation of various stem cell markers in intestinal epithelial neoplasms indicates a potential role of stem cells in tumorigenesis. In this study, the immunoreactivity of potential intestinal stem cell markers ( Sry box transcription factor 9 [Sox9], homeodomain-only protein [Hopx], survivin) and tuft cell marker doublecortin-like kinase 1 (DCLK1) in normal canine intestine and intestinal epithelial neoplasms was investigated. Formalin-fixed paraffin-embedded (FFPE) small and large intestine as well as intestinal neoplasms (55 colorectal adenomas [CRAs], 17 small intestinal adenocarcinomas [SICs], and 12 colorectal adenocarcinomas [CRCs]) were analyzed immunohistologically. Potential stem cell markers Sox9, Hopx, and survivin were detected in the crypts of normal canine small and large intestine. DCLK1+ tuft cells were present in decreasing numbers along the crypt-villus axis of the jejunum and rarely detectable in large intestine. In canine intestinal epithelial tumors, nuclear Sox9 immunoreactivity was detectable in 84.9% (CRA), 80% (CRC), and 77% of epithelial neoplastic cells (SIC). Hopx and survivin were expressed within cytoplasm and nuclei of neoplastic cells in benign and malignant tumors. DCLK1 showed a cytoplasmic reaction within neoplastic cells. The combined score of Hopx, DCLK1, and survivin varied among the examined cases. Overall, malignant tumors showed lower DCLK1 scores but higher Hopx scores in comparison with benign tumors. For survivin, no differences were detectable. In conclusion, stem cell markers Sox9, Hopx, and survivin were detectable at the crypt base and the immunoreactivity of Sox9, DCLK1, survivin, and Hopx was increased in canine intestinal adenomas and adenocarcinomas compared with normal mucosa.

Insight into Cisplatin-Resistance Signaling of W1 Ovarian Cancer Cells Emerges mTOR and HSP27 as Targets for Sensitization Strategies

The microenvironment possesses a strong impact on the tumor chemoresistance when cells bind to components of the extracellular matrix. Here we elucidate the signaling pathways of cisplatin resistance in W1 ovarian cancer cells binding to collagen type 1 (COL1) and signaling interference with constitutive cisplatin resistance in W1CR cells to discover the targets for sensitization. Proteome kinase arrays and Western blots were used to identify the signaling components, their impact on cisplatin resistance was evaluated by inhibitory or knockdown approaches. W1 cell binding to COL1 upregulates integrin-associated signals via FAK/PRAS40/mTOR, confirmed by β1-integrin (ITGB1) knockdown. mTOR appears as key for resistance, its blockade reversed COL1 effects on W1 cell resistance completely. W1CR cells compensate ITGB1-knockdown by upregulation of discoidin domain receptor 1 (DDR1) as alternative COL1 sensor. COL1 binding via DDR1 activates the MAPK pathway, of which JNK1/2 appears critical for COL1-mediated resistance. JNK1/2 inhibition inverts COL1 effects in W1CR cells, whereas intrinsic cisplatin resistance remained unaffected. Remarkably, knockdown of HSP27, another downstream MAPK pathway component overcomes intrinsic resistance completely sensitizing W1CR cells to the level of W1 cells for cisplatin cytotoxicity. Our data confirm the independent regulation of matrix-induced and intrinsic chemoresistance in W1 ovarian cancer cells and offer novel targets for sensitization.

Novel Survivin Peptides Screened With Computer Algorithm Induce Cytotoxic T Lymphocytes With Higher Cytotoxic Efficiency to Cancer Cells

The identification of novel biomarkers and therapeutic targets in advanced cancer is critical for improving cancer diagnosis and therapeutics. Survivin (SV) is highly expressed predominantly in most cancer cells and tissues but is absent or undetectable in terminally differentiated normal adult tissues. Therefore, it functions as an almost universal tumor antigen. Peptides are short chains of amino acids linked by peptide bonds. To obtain novel SV decamers that are able to induce SV-specific cytotoxic T lymphocytes (CTLs) with a higher cytotoxic efficiency against cancer cells, major histocompatibility complex (MHC) peptide binding algorithms were conducted to predict nine modified SV₉₅ decamers (from SV_95–2 to SV_95–10) based on the natural SV_95–104 peptide sequence of ELTLGEFLKL (here defined as SV_95–1). The fluorescent density of each SV₉₅ peptide was determined by a MHC stability assay, followed by the generation of SV₉₅-specific CTLs with each SV₉₅ peptide (from SV_95–1 to SV_95–10) and human dendritic cells (DCs) loaded with Poly(lactic-co-glycolic) acid (PLGA) nanoparticles encapsulated with SV₉₅ peptide. Finally, IFN-γ ELISpot and CytoTox 96^® Non-Radioactive Cytotoxicity Assays were employed to verify their cytotoxic efficiency of the SV₉₅-specific CTLs generated with the corresponding artificial antigen presenting cells (aAPCs) containing SV₉₅ (SV_95–1 to SV_95–10) peptide. Furthermore, the cytotoxicity of the SV₉₅ specific CTLs generated with nine mutated SV₉₅ peptides was compared to the one generated with natural SV_95–1 peptide and TIL2080 cells. The results indicated that the HLA-A2-restricted mutated SV₉₅ epitope decamers (SV_95–6 and SV_95–7) showed significant higher binding ability compared to natural peptide SV_95–1 in MHC stability assay. More importantly, SV_95–specific CTLs with higher cytotoxicity were successfully induced with both SV_95–6 and SV_95–7 peptides, which significantly eliminated target cells (not only SV_95–1 peptide pulsed T2 cells, but also both HLA-A2 and SV positive cancer cells) when compared to those generated with natural SV_95–1 peptide and TIL2080 cells. These findings suggest that the SV_95–6 and SV_95–7 peptides are two novel HLA-A2-restricted CTL epitopes and may be useful for the immunotherapy for patients with survivin expressing cancer.

Targeting MAPK Signaling in Cancer: Mechanisms of Drug Resistance and Sensitivity

Mitogen-activated protein kinase (MAPK) pathways represent ubiquitous signal transduction pathways that regulate all aspects of life and are frequently altered in disease. Here, we focus on the role of MAPK pathways in modulating drug sensitivity and resistance in cancer. We briefly discuss new findings in the extracellular signaling-regulated kinase (ERK) pathway, but mainly focus on the mechanisms how stress activated MAPK pathways, such as p38 MAPK and the Jun N-terminal kinases (JNK), impact the response of cancer cells to chemotherapies and targeted therapies. In this context, we also discuss the role of metabolic and epigenetic aberrations and new therapeutic opportunities arising from these changes.

Large-scale analyses identify a cluster of novel long noncoding RNAs as potential competitive endogenous RNAs in progression of hepatocellular carcinoma

The abnormal expression of noncoding RNAs has attracted increasing interest in the field of hepatocellular carcinoma progression. However, the underlying molecular mechanisms mediated by noncoding RNAs in these processes are unclear. Here, we obtained the expression profiles of long noncoding RNAs, microRNAs, and mRNAs from the Gene Expression Omnibus database and identified hepatocarcinogenesis-specific differentially expressed transcripts. Next, we identified significant Gene Ontology and pathway terms that the differentially expressed transcripts involved in. Using functional analysis and target prediction, we constructed a hepatocellular carcinoma-associated deregulated competitive endogenous RNA network to reveal the potential mechanisms underlying tumor progression. By analyzing The Cancer Genome Atlas dataset, six key long noncoding RNAs showed significant association with overall survival as well as strong correlation with some microRNAs and mRNAs in the competitive endogenous RNA network. We further validated the above results and determined their diagnostic and prognostic value in clinical samples. Importantly, by large-scale analyses, we identified a cluster of long noncoding RNAs, GBAP1, MCM3AP-AS1, SLC16A1-AS1, C3P1, DIO3OS, and HNF4A-AS1 as candidate biomarkers for the diagnosis and prognosis of hepatocellular carcinoma, which will improve our understanding of competitive endogenous RNA-mediated regulatory mechanisms underlying hepatocellular carcinoma development and will provide novel therapeutic targets in the future.

Survivin at a glance

Survivin (also known as BIRC5) is an evolutionarily conserved eukaryotic protein that is essential for cell division and can inhibit cell death. Normally it is only expressed in actively proliferating cells, but is upregulated in most, if not all cancers; consequently, it has received significant attention as a potential oncotherapeutic target. In this Cell Science at a Glance article and accompanying poster, we summarise our knowledge of survivin 21 years on from its initial discovery. We describe the structure, expression and function of survivin, highlight its interactome and conclude by describing anti-survivin strategies being trialled.

An ABCG2 non-substrate anticancer agent FL118 targets drug-resistant cancer stem-like cells and overcomes treatment resistance of human pancreatic cancer

Background

Pancreatic cancer is a deadly disease with a very low 5-year patient survival rate of 6–8%. The major challenges of eliminating pancreatic cancer are treatment resistance and stromal barriers to optimal drug access within the tumor. Therefore, effective molecular targeting drugs with high intra-tumor access and retention are urgently needed for managing this devastating disease in the clinic.

Methods

This study has used the following in vitro and in vivo techniques for the investigation of exceptional anticancer drug FL118’s efficacy in treatment of resistant pancreatic cancer: cell culture; immunoblotting analysis to test protein expression; DNA sub-G1 flow cytometry analyses to test cell death; MTT assay to test cell viability; pancreatic cancer stem cell assays (fluorescence microscopy tracing; matrigel assay; CD44-positive cell colony formation assay); human luciferase-labeled pancreatic tumor orthotopic animal model in vivo imaging; pancreatic cancer patient-derived xenograft (PDX) animal models; and toxicology studies with immune-competent BALB/cj mice and beagle dogs.

Results

Our studies found that FL118 alone preferentially killed cisplatin-resistant cancer cells, while a combination of FL118 with cisplatin synergistically killed resistant pancreatic cancer cells and reduced spheroid formation of treatment-resistant pancreatic cancer stem-like cells. Furthermore, using in vivo-imaging, we found that FL118 in combination with cisplatin strongly inhibited both drug-resistant pancreatic xenograft tumor growth and metastasis. In PDX model, we demonstrated that FL118 alone effectively eliminated PDX tumors, while FL118 in combination with gemcitabine eliminated PDX tumors that showed relative resistance (less sensitivity) to treatment with FL118. These FL118 efficacy results are consistent with our molecular-targeting data showing that FL118 inhibited the expression of multiple antiapoptotic proteins (survivin, Mcl-1, XIAP, cIAP2) and ERCC6, a critical regulator of DNA repair, in treatment-resistant pancreatic stem-like cancer cells. Furthermore, FL118 toxicity studies in BALB/cj mice and beagle dogs indicated that FL118 exhibits favorable hematopoietic and biochemical toxicities.

Conclusion

Together, our studies suggest that FL118 is a promising anticancer drug for further clinical development to effectively treat drug-resistant pancreatic cancer alone or in combination with other pancreatic cancer chemotherapeutic drugs.

Inhibitors of apoptosis: clinical implications in cancer

Inhibitor of apoptosis (IAP) family comprises a group of endogenous proteins that function as main regulators of caspase activity and cell death. They are considered the main culprits in evasion of apoptosis, which is a fundamental hallmark of carcinogenesis. Overexpression of IAP proteins has been documented in various solid and hematological malignancies, rendering them resistant to standard chemotherapeutics and radiation therapy and conferring poor prognosis. This observation has urged their exploitation as therapeutic targets in cancer with promising pre-clinical outcomes. This review describes the structural and functional features of IAP proteins to elucidate the mechanism of their anti-apoptotic activity. We also provide an update on patterns of IAP expression in different tumors, their impact on treatment response and prognosis, as well as the emerging investigational drugs targeting them. This aims at shedding the light on the advances in IAP targeting achieved to date, and encourage further development of clinically applicable therapeutic approaches.

Cytokine Tuning of Intestinal Epithelial Function

The intestine serves as both our largest single barrier to the external environment and the host of more immune cells than any other location in our bodies. Separating these potential combatants is a single layer of dynamic epithelium composed of heterogeneous epithelial subtypes, each uniquely adapted to carry out a subset of the intestine’s diverse functions. In addition to its obvious role in digestion, the intestinal epithelium is responsible for a wide array of critical tasks, including maintaining barrier integrity, preventing invasion by microbial commensals and pathogens, and modulating the intestinal immune system. Communication between these epithelial cells and resident immune cells is crucial for maintaining homeostasis and coordinating appropriate responses to disease and can occur through cell-to-cell contact or by the release or recognition of soluble mediators. The objective of this review is to highlight recent literature illuminating how cytokines and chemokines, both those made by and acting on the intestinal epithelium, orchestrate many of the diverse functions of the intestinal epithelium and its interactions with immune cells in health and disease. Areas of focus include cytokine control of intestinal epithelial proliferation, cell death, and barrier permeability. In addition, the modulation of epithelial-derived cytokines and chemokines by factors such as interactions with stromal and immune cells, pathogen and commensal exposure, and diet will be discussed.

Camptothecin (CPT) and its derivatives are known to target topoisomerase I (Top1) as their mechanism of action: did we miss something in CPT analogue molecular targets for treating human disease such as cancer?

Camptothecin (CPT) was discovered from plant extracts more than 60 years ago. Since then, only two CPT analogues (irinotecan and topotecan) have been approved for cancer treatment, although several thousand CPT derivatives have been synthesized and many of them were actively studied in our research community over the past 6+ decades. In this review article, we briefly summarize: (1) the discovery and early development of CPTs, (2) the recognized CPT mechanism of action (MOA), (3) the synthesis of CPT and CPT analogues, and (4) the structure-activity relationship (SAR) of CPT and its analogues. Next, we provide evidence that certain CPT analogues can exert improved efficacy with low toxicity independently of topoisomerase I (Top1) inhibition; instead, these CPT analogues use novel MOAs by targeting important cancer survival-associated oncogenic proteins and/or by bypassing various treatment-resistant mechanisms. We then present a comprehensive review of the most advanced CPT analogues in clinical development, with the goal of resolving why no new CPTs have been FDA approved for cancer treatment, beyond irinotecan and topotecan. We argue that new CPT Top1 inhibitor drugs are unlikely being found to be significantly better than irinotecan and/or topotecan in terms of the overall antitumor activity and toxicity. The significance of CPT analogues that possess novel MOAs has not been sufficiently recognized so far. In our opinion, this is a research area with great potential to make a breakthrough for development of the next generation of CPT analogues that possess high efficacy (due to novel targets) and low toxicity (due to low inhibition of Top1 activity/function) for effective treatment of human disease, including cancer.

Epithelial TNF Receptor Signaling Promotes Mucosal Repair in Inflammatory Bowel Disease

TNF plays an integral role in inflammatory bowel disease (IBD), as evidenced by the dramatic therapeutic responses in Crohn's disease (CD) patients induced by chimeric anti-TNF mAbs. However, treatment of CD patients with etanercept, a decoy receptor that binds soluble TNF, fails to improve disease. To explore this discrepancy, we investigated the role of TNF signaling in Wnt/β-catenin-mediated intestinal stem cell and progenitor cell expansion in CD patients, human cells, and preclinical mouse models. We hypothesized that TNF exerts beneficial effects on intestinal epithelial cell (IEC) responses to injury. In CD patients, intestinal stem cell and progenitor cell Wnt/β-catenin signaling correlates with inflammation status. TNF-deficient (Tnf^-/-) mice exhibited increased apoptosis, less IEC proliferation, and less Wnt signaling when stimulated with anti-CD3 mAb. Bone marrow (BM) chimera mice revealed that mucosal repair depended on TNF production by BM-derived cells and TNFR expression by radioresistant IECs. Wild-type→Tnfr1/2^-/- BM chimera mice with chronic dextran sodium sulfate colitis exhibited delayed ulcer healing, more mucosal inflammation, and impaired Wnt/β-catenin signaling, consistent with the hypothesis that epithelial TNFR signaling participates in mucosal healing. The direct effect of TNF on stem cells was demonstrated by studies of TNF-induced Wnt/β-catenin target gene expression in murine enteroids and colonoid cultures and TNF-induced β-catenin activation in nontransformed human NCM460 cells (TOPFlash) and mice (TOP-GAL). Together, these data support the hypothesis that TNF plays a beneficial role in enhancing Wnt/β-catenin signaling during ulcer healing in IBD. These novel findings will inform clinicians and therapeutic chemists alike as they strive to develop novel therapies for IBD patients.

Activation of Epithelial Signal Transducer and Activator of Transcription 1 by Interleukin 28 Controls Mucosal Healing in Mice With Colitis and Is Increased in Mucosa of Patients With Inflammatory Bowel Disease

BACKGROUND & AIMS

We investigated the roles of interleukin 28A (also called IL28A or interferon λ2) in intestinal epithelial cell (IEC) activation, studying its effects in mouse models of inflammatory bowel diseases (IBD) and intestinal mucosal healing.

METHODS

Colitis was induced in C57BL/6JCrl mice (controls), mice with IEC-specific disruption of Stat1 (Stat1IEC-KO), mice with disruption of the interferon λ receptor 1 gene (Il28ra-/-), and mice with disruption of the interferon regulatory factor 3 gene (Irf3-/-), with or without disruption of Irf7 (Irf7-/-). We used high-resolution mini-endoscopy and in vivo imaging methods to assess colitis progression. We used 3-dimensional small intestine and colon organoids, along with RNA-Seq and gene ontology methods, to characterize the effects of IL28 on primary IECs. We studied the effects of IL28 on the human intestinal cancer cell line Caco-2 in a wound-healing assay, and in mice colon wounds. Colonic biopsies and resected tissue from patients with IBD (n = 62) and patients without colon inflammation (controls, n = 23) were analyzed by quantitative polymerase chain rection to measure expression of IL28A, IL28RA, and other related cytokines; biopsy samples were also analyzed by immunofluorescence to identify sources of IL28 production. IECs were isolated from patient tissues and incubated with IL28; signal transducer and activator of transcription 1 (STAT1) phosphorylation was measured by immunoblots and confocal imaging.

RESULTS

Lamina propria cells in colon tissues of patients with IBD, and mice with colitis, had increased expression of IL28 compared with controls; levels of IL28R were increased in the colonic epithelium of patients with IBD and mice with colitis. Administration of IL28 induced phosphorylation of STAT1 in primary human and mouse IECs, increasing with dose. Il28ra-/-, Irf3-/-, Irf3-/-Irf7-/-, as well as Stat1IEC-KO mice, developed more severe colitis after administration of dextran sulfate sodium than control mice, with reduced epithelial restitution. Il28ra-/- and Stat1IEC-KO mice also developed more severe colitis in response to oxazolone than control mice. We found IL28 to induce phosphorylation (activation) of STAT1 in epithelial cells, leading to their proliferation in organoid culture. Administration of IL28 to mice with induced colonic wounds promoted mucosal healing.

CONCLUSIONS

IL28 controls proliferation of IECs in mice with colitis and accelerates mucosal healing by activating STAT1. IL28 might be developed as a therapeutic agent for patients with IBD.

Differential Impacts of Alternative Splicing Networks on Apoptosis

Apoptosis functions as a common mechanism to eliminate unnecessary or damaged cells during cell renewal and tissue development in multicellular organisms. More than 200 proteins constitute complex networks involved in apoptotic regulation. Imbalanced expressions of apoptosis-related factors frequently lead to malignant diseases. The biological functions of several apoptotic factors are manipulated through alternative splicing mechanisms which expand gene diversity by generating discrete variants from one messenger RNA precursor. It is widely observed that alternatively-spliced variants encoded from apoptosis-related genes exhibit differential effects on apoptotic regulation. Alternative splicing events are meticulously regulated by the interplay between trans-splicing factors and cis-responsive elements surrounding the regulated exons. The major focus of this review is to highlight recent studies that illustrate the influences of alternative splicing networks on apoptotic regulation which participates in diverse cellular processes and diseases.