Development of Novel Bioluminescent Biosensors Monitoring the Conformation and Activity of the Merlin Tumour Suppressor

Solid tumours can universally evade contact inhibition of proliferation (CIP), a mechanism halting cell proliferation when cell-cell contact occurs. Merlin, an ERM-like protein, crucially regulates CIP and is frequently deactivated in various cancers, indicating its significance as a tumour suppressor in cancer biology. Despite extensive investigations into Merlin's role in cancer, its lack of intrinsic catalytic activity and frequent conformation changes have made it notoriously challenging to study. To address this challenge, we harnessed innovative luciferase technologies to create and validate a NanoBiT split-luciferase biosensor system in which Merlin is cloned between two split components (LgBiT and SmBiT) of NanoLuc luciferase. This system enables precise quantification of Merlin's conformation and activity both in vitro and within living cells. This biosensor significantly enhances the study of Merlin's molecular functions, serving as a potent tool for exploring its contributions to CIP and tumorigenesis.

Targeting Protein Tyrosine Phosphatases to Improve Cancer Immunotherapies

Advances in immunotherapy have brought significant therapeutic benefits to many cancer patients. Nonetheless, many cancer types are refractory to current immunotherapeutic approaches, meaning that further targets are required to increase the number of patients who benefit from these technologies. Protein tyrosine phosphatases (PTPs) have long been recognised to play a vital role in the regulation of cancer cell biology and the immune response. In this review, we summarize the evidence for both the pro-tumorigenic and tumour-suppressor function of non-receptor PTPs in cancer cells and discuss recent data showing that several of these enzymes act as intracellular immune checkpoints that suppress effective tumour immunity. We highlight new data showing that the deletion of inhibitory PTPs is a rational approach to improve the outcomes of adoptive T cell-based cancer immunotherapies and describe recent progress in the development of PTP inhibitors as anti-cancer drugs.

The Role of the AT-Rich Interaction Domain 1A Gene (ARID1A) in Human Carcinogenesis

The switch/sucrose non-fermentable (SWI/SNF) (SWI/SNF) complex uses energy from ATP hydrolysis to mobilise nucleosomes on chromatin. Components of SWI/SNF are mutated in 20% of all human cancers, of which mutations in AT-rich binding domain protein 1A (ARID1A) are the most common. ARID1A is mutated in nearly half of ovarian clear cell carcinoma and around one-third of endometrial and ovarian carcinomas of the endometrioid type. This review will examine in detail the molecular functions of ARID1A, including its role in cell cycle control, enhancer regulation, and the prevention of telomerase activity. ARID1A has key roles in the maintenance of genomic integrity, including DNA double-stranded break repair, DNA decatenation, integrity of the cohesin complex, and reduction in replication stress, and is also involved in mismatch repair. The role of ARID1A loss in the pathogenesis of some of the most common human cancers is discussed, with a particular emphasis on gynaecological cancers. Finally, several promising synthetic lethal strategies, which exploit the specific vulnerabilities of ARID1A-deficient cancer cells, are briefly mentioned.

RYBP contributes to improved prognosis in colorectal cancer via regulation of cell cycle, apoptosis and oxaliplatin sensitivity

Ring1 and YY‑1 binding protein (RYBP) is a member of the polycomb repressive complex 1 and serves as a transcriptional suppressor via epigenetic modification. RYBP has a tumour‑suppressive role in solid tumours, but its function in colorectal cancer (CRC) remains unknown. The present study evaluated the expression of RYBP using immunohistochemistry in 140 cases of primary CRC and 11 patient‑matched cases of liver metastases. Using CRC cell lines with different TP53 gene status such as HCT116 (TP53wt/wt), HCT116 (TP53‑/‑), SW48 and DLD‑1 cells, proliferation, cell cycle progression and apoptosis, as well as the effect of RYBP on oxaliplatin sensitivity, were assessed. Clinical data showed that low RYBP expression was significantly associated with risk of distant metastasis and recurrence, and patients with high RYBP expression demonstrated significantly better cancer‑specific and disease‑free survival. In vitro experiments revealed that RYBP suppressed cell proliferation by inducing cell cycle arrest and apoptosis in TP53 wild‑type cells. In addition, endogenous RYBP overexpression enhanced sensitivity to oxaliplatin. Therefore, RYBP may contribute to improved prognosis in CRC by regulating the cell cycle, apoptosis and oxaliplatin sensitivity via the p53‑mediated pathway.

Tissue-Specific Tumour Suppressor and Oncogenic Activities of the Polycomb-like Protein MTF2

The Polycomb repressive complex 2 (PRC2) is a conserved chromatin-remodelling complex that catalyses the trimethylation of histone H3 lysine 27 (H3K27me3), a mark associated with gene silencing. PRC2 regulates chromatin structure and gene expression during organismal and tissue development and tissue homeostasis in the adult. PRC2 core subunits are associated with various accessory proteins that modulate its function and recruitment to target genes. The multimeric composition of accessory proteins results in two distinct variant complexes of PRC2, PRC2.1 and PRC2.2. Metal response element-binding transcription factor 2 (MTF2) is one of the Polycomb-like proteins (PCLs) that forms the PRC2.1 complex. MTF2 is highly conserved, and as an accessory subunit of PRC2, it has important roles in embryonic stem cell self-renewal and differentiation, development, and cancer progression. Here, we review the impact of MTF2 in PRC2 complex assembly, catalytic activity, and spatiotemporal function. The emerging paradoxical evidence suggesting that MTF2 has divergent roles as either a tumour suppressor or an oncogene in different tissues merits further investigations. Altogether, our review illuminates the context-dependent roles of MTF2 in Polycomb group (PcG) protein-mediated epigenetic regulation. Its impact on disease paves the way for a deeper understanding of epigenetic regulation and novel therapeutic strategies.

BRCA1 and BRCA2 carriers with breast, ovarian and prostate cancer demonstrate a different pattern of metastatic disease compared with non-carriers: results from a rapid autopsy programme

AIM

To catalogue and compare the pattern of metastatic disease in germline BRCA1/2 pathogenic mutation carriers and non-carriers with breast, ovarian and prostate cancer from a rapid autopsy programme.

METHODS AND RESULTS

The number of metastases in the major body systems and the proportion of participants with metastases were documented in 50 participants (19 germline mutation carriers). Analysis was conducted on the participants' pattern of disease for the different cancers and mutation subgroups. The four commonly affected organ systems were the digestive (liver only) (82%), respiratory (76%), gastrointestinal (65%) and reticuloendothelial (42%). There were significant differences in the pattern of metastatic breast cancer in BRCA1/2 germline carriers compared with non-carriers. Breast cancer carriers had significantly fewer organ systems involved (median n = 3, range = 1-3) compared with non-carriers (median n = 9, range = 1-7) (P = 0.03). BRCA1/2 carriers with ovarian carcinomas had significantly more organ systems with metastatic carcinoma (median n = 10, range = 3-8) than non-carriers (median n = 5, range = 3-5) (P < 0.001). There were no significant differences in the number of involved systems in BRCA2 carriers compared with non-carriers with prostate cancer (P = 1.0). There was an absence of locoregional disease (6.5%) compared with distant disease (93.5%) among the three cancer subtypes (P < 0.001). The majority of metastatic deposits (97%) collected during the autopsy were identified by recent diagnostic imaging.

CONCLUSION

Even though a major limitation of this study is that our numbers are small, especially in the breast cancer carrier group, the metastatic patterns of breast and ovarian cancers may be impacted by BRCA1/2 carrier status, suggesting that tumours derived from patients with these mutations use different mechanisms of dissemination. The findings may focus clinical diagnostic imaging for monitoring metastases where whole-body imaging resources are scant.

Human Neuralized is a novel tumour suppressor targeting Wnt/β-catenin signalling in colon cancer

While there is growing evidence that many epigenetically silenced genes in cancer are tumour suppressor candidates, their significance in cancer biology remains unclear. Here, we identify human Neuralized (NEURL), which acts as a novel tumour suppressor targeting oncogenic Wnt/β-catenin signalling in human cancers. The expression of NEURL is epigenetically regulated and markedly suppressed in human colorectal cancer. We, therefore, considered NEURL to be a bona fide tumour suppressor in colorectal cancer and demonstrate that this tumour suppressive function depends on NEURL-mediated oncogenic β-catenin degradation. We find that NEURL acts as an E3 ubiquitin ligase, interacting directly with oncogenic β-catenin, and reducing its cytoplasmic levels in a GSK3β- and β-TrCP-independent manner, indicating that NEURL-β-catenin interactions can lead to a disruption of the canonical Wnt/β-catenin pathway. This study suggests that NEURL is a therapeutic target against human cancers and that it acts by regulating oncogenic Wnt/β-catenin signalling.

MTAP deficiency contributes to immune landscape remodelling and tumour evasion

Methylthioadenosine phosphorylase (MTAP) deficiency occurs in various malignancies and is associated with poor survival in cancer patients. However, the mechanisms underlying tumour progression due to MTAP loss are yet to be elucidated. Utilizing integrated analyses of the transcriptome, proteome and secretome, we demonstrated that MTAP deficiency alters tumour-intrinsic, immune-related pathways and reprograms cytokine profiles towards a tumour-favourable environment. Additionally, MTAP-knockout cells exhibited a marked increase in the immune checkpoint protein PD-L1. Upon co-culturing primary T cells with cancer cells, MTAP loss-mediated PD-L1 upregulation inhibited T cell-mediated killing activity and induced several T cell exhaustion markers. In two xenograft tumour models, we showed a modest increase in average volume of tumours derived from MTAP-deficient cells than that of MTAP-proficient tumours. Surprisingly, a remarkable increase in tumour size was observed in humanized mice bearing MTAP-deficient tumours, as compared to their MTAP-expressing counterparts. Following immunophenotypic characterization of tumour-infiltrating leukocytes by mass cytometry analysis, MTAP-deficient tumours were found to display decreased immune infiltrates with lower proportions of both T lymphocytes and natural killer cells and higher proportions of immunosuppressive cells as compared to MTAP-expressing tumour xenografts. Taken together, our results suggest that MTAP deficiency restructures the tumour immune microenvironment, promoting tumour progression and immune evasion.

Human nucleolar protein 7 (NOL7) is required for early pre-rRNA accumulation and pre-18S rRNA processing

The main components of the essential cellular process of eukaryotic ribosome biogenesis are highly conserved from yeast to humans. Among these, the U3 Associated Proteins (UTPs) are a small subunit processome subcomplex that coordinate the first two steps of ribosome biogenesis in transcription and pre-18S processing. While we have identified the human counterparts of most of the yeast Utps, the homologs of yeast Utp9 and Bud21 (Utp16) have remained elusive. In this study, we find that NOL7 is the likely ortholog of Bud21. Previously described as a tumour suppressor through regulation of antiangiogenic transcripts, we now show that NOL7 is required for early pre-rRNA accumulation and pre-18S rRNA processing in human cells. These roles lead to decreased protein synthesis and induction of the nucleolar stress response upon NOL7 depletion. Beyond Bud21's nonessential role in yeast, we establish human NOL7 as an essential UTP that is necessary to maintain both early pre-rRNA levels and processing.

Aberrant regulation of CXCR4 in cancer via deviant microRNA-targeted interactions

CXCR4 is involved in many facets of cancer, including being a major player in establishing metastasis. This is in part due to the deregulation of CXCR4, which can be attributed to many genetic and epigenetic mechanisms, including aberrant microRNA-CXCR4 interaction. MicroRNAs (miRNAs) are a type of small non-coding RNA that primarily targets the 3' UTR of mRNA transcripts, which in turn suppresses mRNA and subsequent protein expression. In this review, we reported and characterized the many aberrant miRNA-CXCR4 interactions that occur throughout human cancers. In particular, we reported known target sequences located on the 3' UTR of CXCR4 transcripts that tumour suppressor miRNAs bind and therefore regulate expression by. From these aberrant interactions, we also documented affected downstream genes/pathways and whether a particular tumour suppressor miRNA was reported as a prognostic marker in its respected cancer type. In addition, a limited number of cancer-causing miRNAs coined 'oncomirs' were reported and described in relation to CXCR4 regulation. Moreover, the mechanisms underlying both tumour suppressor and oncomir deregulations concerning CXCR4 expression were also explored. Furthermore, the miR-146a-CXCR4 axis was delineated in oncoviral infected endothelial cells in the context of virus-causing cancers. Lastly, miRNA-driven therapies and CXCR4 antagonist drugs were discussed as potential future treatment options in reported cancers pertaining to deregulated miRNA-CXCR4 interactions.

Low Expression of AGPAT5 Is Associated With Clinical Stage and Poor Prognosis in Colorectal Cancer and Contributes to Tumour Progression

Background:

Colorectal cancer (CRC) has a high prevalence and poor prognosis. This study aimed to identify biomarkers related to the clinical stage (I-IV) of CRC.

Methods:

The LinkedOmics database was used as the discovery cohort, and two Gene Expression Omnibus (GEO) databases (GSE41258 and GSE422848) served as validation cohorts. The trend test of genes related to clinical stage (I-IV) of CRC patients was identified by the Jonckheere-Terpstra test. The cBioPortal database, Gene Expression Profiling Interactive Analysis (GEPIA) and PrognoScan databases were used to explore the expression change and prognostic value of clinical stage-related genes in CRC patients. CRC cells overexpressed AGPAT5 were constructed and used for cell counting kit-8 (CCK-8), flow cytometric, and wound healing assays in vitro.

Results:

We identified four clinical stage-related genes, GSR, AGPAT5, CRLF1, and NPR3, in CRC. The CNA frequencies of GSR, CRLF1, AGPAT5, and NPR3 occurred in 11%, 2.4%, 13%, and 3% of patients, respectively. The expression of GSR and AGPAT5 tended to decrease with CRC stage (I-IV) progression, and the expression of CRLF1 and NPR3 tended to increase with CRC stage (I-IV) progression. Compared with the normal group, AGPAT5 expression was markedly decreased in stage IV CRC. Higher GSR and AGPAT5 expression levels were associated with better overall survival (OS) and disease-free survival (DFS) in CRC patients. Lower CRLF1 and NPR3 expression levels were associated with better OS and DFS in CRC. GSR, CRLF1, AGPAT5, and NPR3 expression were related to CRC progression, microsatellite instability, and tumour purity in CRC. Furthermore, AGPAT5 was downregulated in CRC cell lines, and overexpression of AGPAT5 inhibited cell proliferation and migration and promoted cell apoptosis in CRC cells.

Conclusion:

Low AGPAT5 expression may serve as a poor prognostic factor and clinical stage biomarker in CRC. In addition, AGPAT5 acts as a tumour suppressor in CRC progression.

NDRG1 in Cancer: A Suppressor, Promoter, or Both?

N-myc downregulated gene-1 (NDRG1) has been variably reported as a metastasis suppressor, a biomarker of poor outcome, and a facilitator of disease progression in a range of different cancers. NDRG1 is poorly understood in cancer due to its context-dependent and pleiotropic functions. Within breast cancer, NDRG1 is reported to be either a facilitator of, or an inhibitor of tumour progression and metastasis. The wide array of roles played by NDRG1 are dependent on post-translational modifications and subcellular localization, as well as the cellular context, for example, cancer type. We present an update on NDRG1, and its association with hallmarks of cancer such as hypoxia, its interaction with oncogenic proteins such as p53 as well its role in oncogenic and metastasis pathways in breast and other cancers. We further comment on its functional implications as a metastasis suppressor and promoter, its clinical relevance, and discuss its therapeutic targetability in different cancers.

PTEN Protein Phosphatase Activity Is Not Required for Tumour Suppression in the Mouse Prostate

Loss PTEN function is one of the most common events driving aggressive prostate cancers and biochemically, PTEN is a lipid phosphatase which opposes the activation of the oncogenic PI3K-AKT signalling network. However, PTEN also has additional potential mechanisms of action, including protein phosphatase activity. Using a mutant enzyme, PTEN Y138L, which selectively lacks protein phosphatase activity, we characterised genetically modified mice lacking either the full function of PTEN in the prostate gland or only lacking protein phosphatase activity. The phenotypes of mice carrying a single allele of either wild-type Pten or Pten^Y138L in the prostate were similar, with common prostatic intraepithelial neoplasia (PIN) and similar gene expression profiles. However, the latter group, lacking PTEN protein phosphatase activity additionally showed lymphocyte infiltration around PIN and an increased immune cell gene expression signature. Prostate adenocarcinoma, elevated proliferation and AKT activation were only frequently observed when PTEN was fully deleted. We also identify a common gene expression signature of PTEN loss conserved in other studies (including Nkx3.1, Tnf and Cd44). We provide further insight into tumour development in the prostate driven by loss of PTEN function and show that PTEN protein phosphatase activity is not required for tumour suppression.

miR-2392 functions as tumour suppressor and inhibits malignant progression of hepatocellular carcinoma via directly targeting JAG2

BACKGROUND & AIMS

Dysregulation of microRNA (miRNA) expression in various cancers and their vital roles in malignant progression of cancers are well investigated. Our previous studies have analysed miRNAs that promote malignant progression in hepatocellular carcinoma (HCC); this study aims to systematically elucidate the mechanism of metastasis suppressor miRNAs in HCC.

METHODS

High-throughput RNA sequencing was used to identify anti-metastatic miRNAs. The relative expression levels of miRNAs were confirmed by qRT-PCR. The biological functions of miRNAs were detected in vitro and in vivo. Circulating tumour cells (CTCs) were enriched from blood samples of HCC patients and cultured by three-dimensional (3D) system. Kaplan-Meier and Cox regression were used to analyse the value of potential target mRNAs on overall survival.

RESULTS

miR-2392 was significantly down-regulated in HCC. Overexpression of miR-2392 suppressed proliferation, clonogenicity, mobility, spheroid formation and maintenance of cancer stem cells (CSC)-like characteristics in HCC cells. CTCs from HCC patients with lower serum miR-2392 level had stronger cell spheroid formation ability. A negative correlation between the content of miR-2392 in serum and the number of CTC spheroids had been found. We identified Jagged2 (JAG2) as a direct target of miR-2392. miR-2392 inhibited the expression of JAG2 by targeting 3'-UTR of JAG2. Down-regulation of JAG2 inhibited the overexpression effects of miR-2392 in vitro and in vivo. JAG2 is highly expressed in HCC and is closely related to poor prognosis and survival of patients.

CONCLUSIONS

miR-2392 may play a role as a tumour suppressor to guide the individualized precise treatment of HCC.

p53 gene delivery via a recombinant Salmonella enterica Typhimurium leads to human bladder carcinoma cell death in vitro

Numerous studies have attempted to restore the function of the tumour suppressor p53 as an anticancer strategy through gene delivery. However, most studies employed non-bacterial vectors to deliver p53. Various facultative and obligate anaerobic bacteria have been proposed as vectors because of their intrinsic tumour targeting ability and antitumour activity. Salmonella enterica Typhimurium is the most studied bacterial vector in anticancer therapy. We used the previously designed χ11218 strain of S. enterica Typhimurium, displaying regulated delayed lysis, as a vector for delivering p53 to human bladder carcinoma cells, restoring wild-type p53 protein function. We cloned p53 into pYA4545 (containing a eukaryotic expression system) to generate the χ11218 pYA4545p53 strain. Cloning of p53 did not affect the growth or interfere with the invasive and replicative capacity of χ11218 bacteria in tumour cells. Human bladder carcinoma cells (expressing mutated p53) transfected with pYA4545p53 showed a significant increase in the expression of p53 protein. We demonstrated that p53 supplied by χ11218 significantly decreased the viability of human bladder cancer cells in a dose-dependent manner. This study demonstrates the applicability of the attenuated χ11218 strain as a vector for DNA plasmids expressing tumour suppressor genes.

Next generation sequencing of BRCA genes in glioblastoma multiform Egyptian patients: a pilot study

BACKGROUND

Germ line mutations of BRCA1 and BRCA2 were correlated with a variety of cancer Authors aimed to use next-generation sequencing (NGS) to detect BRCA1 and BRCA2 germ line mutations in glioblastoma multiform (GBM) Egyptian patients.

MATERIALS AND METHODS

Genomic DNA was extracted from six GBM cases, amplified using Ion AmpliSeq BRCA1 and BRCA2 panel. DNA libraries were pooled, barcoded and finally sequenced using Ion Torrent Personal Genome Machine sequencer.

RESULTS

BRCA1 the previously reported rs1799966, rs1799950, rs16941 were found in five cases and they are in a linkage disequilibrium forming two distinct haplotypes, which might support their role in cancer predisposition. Out of the 18 reported variants in BRCA2, three denovo mutations were detected which leads to frame shift.

CONCLUSION

Further studies on large number of GBM patients and control cases to determine BRCA1 and BRCA2 germline mutations and haplotypes; diagnostic and prognostic role are encouraged.

The RAF Kinase Inhibitor Protein (RKIP): Good as Tumour Suppressor, Bad for the Heart

The RAF kinase inhibitor protein, RKIP, is a dual inhibitor of the RAF1 kinase and the G protein-coupled receptor kinase 2, GRK2. By inhibition of the RAF1-MAPK (mitogen-activated protein kinase) pathway, RKIP acts as a beneficial tumour suppressor. By inhibition of GRK2, RKIP counteracts GRK2-mediated desensitisation of G protein-coupled receptor (GPCR) signalling. GRK2 inhibition is considered to be cardioprotective under conditions of exaggerated GRK2 activity such as heart failure. However, cardioprotective GRK2 inhibition and pro-survival RAF1-MAPK pathway inhibition counteract each other, because inhibition of the pro-survival RAF1-MAPK cascade is detrimental for the heart. Therefore, the question arises, what is the net effect of these apparently divergent functions of RKIP in vivo? The available data show that, on one hand, GRK2 inhibition promotes cardioprotective signalling in isolated cardiomyocytes. On the other hand, inhibition of the pro-survival RAF1-MAPK pathway by RKIP deteriorates cardiomyocyte viability. In agreement with cardiotoxic effects, endogenous RKIP promotes cardiac fibrosis under conditions of cardiac stress, and transgenic RKIP induces heart dysfunction. Supported by next-generation sequencing (NGS) data of the RKIP-induced cardiac transcriptome, this review provides an overview of different RKIP functions and explains how beneficial GRK2 inhibition can go awry by RAF1-MAPK pathway inhibition. Based on RKIP studies, requirements for the development of a cardioprotective GRK2 inhibitor are deduced.

Low BACH2 Expression Predicts Adverse Outcome in Chronic Lymphocytic Leukaemia

Chronic lymphocytic leukaemia (CLL) is a heterogeneous disease with a highly variable clinical outcome. There are well-established CLL prognostic biomarkers that have transformed treatment and improved the understanding of CLL biology. Here, we have studied the clinical significance of two crucial B cell regulators, BACH2 (BTB and CNC homology 1, basic leucine zipper transcription factor 2) and BCL6 (B-cell CLL/lymphoma 6), in a cohort of 102 CLL patients and determined the protein interaction networks that they participate in using MEC-1 CLL cells. We observed that CLL patients expressing low levels of BCL6 and BACH2 RNA had significantly shorter overall survival (OS) than high BCL6- and BACH2-expressing cases. Notably, their low expression specifically decreased the OS of immunoglobulin heavy chain variable region-mutated (IGHV-M) CLL patients, as well as those with 11q and 13q deletions. Similar to the RNA data, a low BACH2 protein expression was associated with a significantly shorter OS than a high expression. There was no direct interaction observed between BACH2 and BCL6 in MEC-1 CLL cells, but they shared protein networks that included fifty different proteins. Interestingly, a prognostic index (PI) model that we generated, using integrative risk score values of BACH2 RNA expression, age, and 17p deletion status, predicted patient outcomes in our cohort. Taken together, these data have shown for the first time a possible prognostic role for BACH2 in CLL and have revealed protein interaction networks shared by BCL6 and BACH2, indicating a significant role for BACH2 and BCL6 in key cellular processes, including ubiquitination mediated B-cell receptor functions, nucleic acid metabolism, protein degradation, and homeostasis in CLL biology.

Targeting Oncogenic Transcriptional Networks in Neuroblastoma: From N-Myc to Epigenetic Drugs

Neuroblastoma (NB) is one of the most frequently occurring neurogenic extracranial solid cancers in childhood and infancy. Over the years, many pieces of evidence suggested that NB development is controlled by gene expression dysregulation. These unleashed programs that outline NB cancer cells make them highly dependent on specific tuning of gene expression, which can act co-operatively to define the differentiation state, cell identity, and specialized functions. The peculiar regulation is mainly caused by genetic and epigenetic alterations, resulting in the dependency on a small set of key master transcriptional regulators as the convergence point of multiple signalling pathways. In this review, we provide a comprehensive blueprint of transcriptional regulation bearing NB initiation and progression, unveiling the complexity of novel oncogenic and tumour suppressive regulatory networks of this pathology. Furthermore, we underline the significance of multi-target therapies against these hallmarks, showing how novel approaches, together with chemotherapy, surgery, or radiotherapy, can have substantial antineoplastic effects, disrupting a wide variety of tumorigenic pathways through combinations of different treatments.

CG7379 and ING1 suppress cancer cell invasion by maintaining cell-cell junction integrity

Approximately 90% of cancer-related deaths can be attributed to a tumour's ability to spread. We have identified CG7379, the fly orthologue of human ING1, as a potent invasion suppressor. ING1 is a type II tumour suppressor with well-established roles in the transcriptional regulation of genes that control cell proliferation, response to DNA damage, oncogene-induced senescence and apoptosis. Recent work suggests a possible role for ING1 in cancer cell invasion and metastasis, but the molecular mechanism underlying this observation is lacking. Our results show that reduced expression of CG7379 promotes invasion in vivo in Drosophila, reduces the junctional localization of several adherens and septate junction components, and severely disrupts cell-cell junction architecture. Similarly, ING1 knockdown significantly enhances invasion in vitro and disrupts E-cadherin distribution at cell-cell junctions. A transcriptome analysis reveals that loss of ING1 affects the expression of several junctional and cytoskeletal modulators, confirming ING1 as an invasion suppressor and a key regulator of cell-cell junction integrity.

A rare PALB2 germline variant causing G2/M cell cycle arrest is associated with isolated myelosarcoma in infancy

BACKGROUND

Isolated myelosarcoma of infancy is a rare presentation of acute myelogenous leukaemia (AML). Because of its rarity and early onset in infancy underlying genetic predisposition is potentially relevant in disease initiation.

METHODS AND RESULTS

We report an oncologic emergency in an infant with thoracic and intraspinal aleukaemic myeloid sarcoma causing acute myelon compression and lower leg palsy. Whole-exome sequencing of the patient's germline DNA identified a rare PALB2 (OMIM 610355) variant (p.A1079S), which is located in a domain critical for the gene's proper function within the homology-directed repair pathway. In line with potential DNA damage repair defects mediated by the PALB2 deregulation, the patient's fibroblasts showed increased sensitivity towards radiation and DNA intercalating agents.

CONCLUSION

Therefore, we suggest PALB2 p.A1079S as a pathogenic variant potentially contributing to the here observed patient phenotype.

Recent Advances in Pathology: the 2021 Annual Review Issue of The Journal of Pathology

The 2021 Annual Review Issue of The Journal of Pathology contains 14 invited reviews on current research areas of particular importance in pathology. The subjects included here reflect the broad range of interests covered by the journal, including both basic and applied research fields but always with the aim of improving our understanding of human disease. This year, our reviews encompass the huge impact of the COVID-19 pandemic, the development and application of biomarkers for immune checkpoint inhibitors, recent advances in multiplexing antigen/nucleic acid detection in situ, the use of genomics to aid drug discovery, organoid methodologies in research, the microbiome in cancer, the role of macrophage-stroma interactions in fibrosis, and TGF-β as a driver of fibrosis in multiple pathologies. Other reviews revisit the p53 field and its lack of clinical impact to date, dissect the genetics of mitochondrial diseases, summarise the cells of origin and genetics of sarcomagenesis, provide new data on the role of TRIM28 in tumour predisposition, review our current understanding of cancer stem cell niches, and the function and regulation of p63. The reviews are authored by experts in their field from academia and industry, and provide comprehensive updates of the chosen areas, in which there has been considerable recent progress. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Resistance to Targeted Therapy and RASSF1A Loss in Melanoma: What Are We Missing?

Melanoma is one of the most aggressive forms of skin cancer and is therapeutically challenging, considering its high mutation rate. Following the development of therapies to target BRAF, the most frequently found mutation in melanoma, promising therapeutic responses were observed. While mono- and combination therapies to target the MAPK cascade did induce a therapeutic response in BRAF-mutated melanomas, the development of resistance to MAPK-targeted therapies remains a challenge for a high proportion of patients. Resistance mechanisms are varied and can be categorised as intrinsic, acquired, and adaptive. RASSF1A is a tumour suppressor that plays an integral role in the maintenance of cellular homeostasis as a central signalling hub. RASSF1A tumour suppressor activity is commonly lost in melanoma, mainly by aberrant promoter hypermethylation. RASSF1A loss could be associated with several mechanisms of resistance to MAPK inhibition considering that most of the signalling pathways that RASSF1A controls are found to be altered targeted therapy resistant melanomas. Herein, we discuss resistance mechanisms in detail and the potential role for RASSF1A reactivation to re-sensitise BRAF mutant melanomas to therapy.

NRF2 and the Ambiguous Consequences of Its Activation during Initiation and the Subsequent Stages of Tumourigenesis

NF-E2 p45-related factor 2 (NRF2, encoded in the human by NFE2L2) mediates short-term adaptation to thiol-reactive stressors. In normal cells, activation of NRF2 by a thiol-reactive stressor helps prevent, for a limited period of time, the initiation of cancer by chemical carcinogens through induction of genes encoding drug-metabolising enzymes. However, in many tumour types, NRF2 is permanently upregulated. In such cases, its overexpressed target genes support the promotion and progression of cancer by suppressing oxidative stress, because they constitutively increase the capacity to scavenge reactive oxygen species (ROS), and they support cell proliferation by increasing ribonucleotide synthesis, serine biosynthesis and autophagy. Herein, we describe cancer chemoprevention and the discovery of the essential role played by NRF2 in orchestrating protection against chemical carcinogenesis. We similarly describe the discoveries of somatic mutations in NFE2L2 and the gene encoding the principal NRF2 repressor, Kelch-like ECH-associated protein 1 (KEAP1) along with that encoding a component of the E3 ubiquitin-ligase complex Cullin 3 (CUL3), which result in permanent activation of NRF2, and the recognition that such mutations occur frequently in many types of cancer. Notably, mutations in NFE2L2, KEAP1 and CUL3 that cause persistent upregulation of NRF2 often co-exist with mutations that activate KRAS and the PI3K-PKB/Akt pathway, suggesting NRF2 supports growth of tumours in which KRAS or PKB/Akt are hyperactive. Besides somatic mutations, NRF2 activation in human tumours can occur by other means, such as alternative splicing that results in a NRF2 protein which lacks the KEAP1-binding domain or overexpression of other KEAP1-binding partners that compete with NRF2. Lastly, as NRF2 upregulation is associated with resistance to cancer chemotherapy and radiotherapy, we describe strategies that might be employed to suppress growth and overcome drug resistance in tumours with overactive NRF2.

Long non-coding RNAs in ovarian cancer: expression profile and functional spectrum

Long non-coding RNAs (lncRNAs), initially recognized as byproducts of the transcription process, have been proven to play crucial modulatory roles in preserving overall homoeostasis of cells and tissues. Furthermore, aberrant levels of these transcripts have been shown to contribute many diseases, including cancer. Among these, many aspects of ovarian cancer biology have been found to be regulated by lncRNAs, including cancer initiation, progression and dissemination. In this review, we summarize recent studies to highlight the various roles of lncRNAs in ovary in normal and pathological conditions, immune system, diagnosis, prognosis, and therapy. We address lncRNAs that have been extensively studied in ovarian cancer and their contribution to cellular dynamics.

Context is key: Understanding the regulation, functional control, and activities of the p53 tumour suppressor

The p53 tumour suppressor is considered one of the most critical genes in cancer biology. By upregulating apoptosis, cell cycle arrest, and DNA damage repair in normal cells, p53 prevents the propagation of cells with tumorigenic potential; therefore, mutations in p53 are associated with carcinogenic transformation and can be accompanied by the accumulation of a novel gain-of-function oncogenic protein, mutant p53. Although p53 is most often understood to utilize context-dependent post-translational modifications to achieve regulation of its many target genes, recent research has also sought to define other mechanisms of regulating p53 gene expression prior to translation and to understand how this alternative regulation of p53 may influence target gene expression and cellular outcome. This review attempts to summarize what is known about p53 regulation at the transcriptional, post-transcriptional, and post-translational levels while paying special attention to the ways in which context may influence p53 regulation and subsequent regulation of its target genes.

Novel tumour suppressor roles for GZMA and RASGRP1 in Theileria annulata-transformed macrophages and human B lymphoma cells

Theileria annulata is a tick-transmitted apicomplexan parasite that infects and transforms bovine leukocytes into disseminating tumours that cause a disease called tropical theileriosis. Using comparative transcriptomics we identified genes transcriptionally perturbed during Theileria-induced leukocyte transformation. Dataset comparisons highlighted a small set of genes associated with Theileria-transformed leukocyte dissemination. The roles of Granzyme A (GZMA) and RAS guanyl-releasing protein 1 (RASGRP1) were verified by CRISPR/Cas9-mediated knockdown. Knocking down expression of GZMA and RASGRP1 in attenuated macrophages led to a regain in their dissemination in Rag2/γC mice confirming their role as dissemination suppressors in vivo. We further evaluated the roles of GZMA and RASGRP1 in human B lymphomas by comparing the transcriptome of 934 human cancer cell lines to that of Theileria-transformed bovine host cells. We confirmed dampened dissemination potential of human B lymphomas that overexpress GZMA and RASGRP1. Our results provide evidence that GZMA and RASGRP1 have a novel tumour suppressor function in both T. annulata-infected bovine host leukocytes and in human B lymphomas.

Human CtIP: A 'double agent' in DNA repair and tumorigenesis

Human CtIP was originally identified as an interactor of the retinoblastoma protein and BRCA1, two bona fide tumour suppressors frequently mutated in cancer. CtIP is renowned for its role in the resection of DNA double-strand breaks (DSBs) during homologous recombination, a largely error-free DNA repair pathway crucial in maintaining genome integrity. However, CtIP-dependent DNA end resection is equally accountable for alternative end-joining, a mutagenic DSB repair mechanism implicated in oncogenic chromosomal translocations. In addition, CtIP contributes to transcriptional regulation of G1/S transition, DNA damage checkpoint signalling, and replication fork protection pathways. In this review, we present a perspective on the current state of knowledge regarding the tumour-suppressive and oncogenic properties of CtIP and provide an overview of their relevance for cancer development, progression, and therapy.

MAM domain containing 2 is a potential breast cancer biomarker that exhibits tumour-suppressive activity

Objectives

The aim of this study was to discover new potential biomarkers of breast cancer and investigate their cellular functions.

Materials and methods

We analysed the gene expression profiles of matched pairs of breast tumour and normal tissues from 24 breast cancer patients. Tetracycline‐inducible MAMDC2 expression system was established and used to evaluate cell proliferation in vitro and in vivo. MAMDC2‐mediated signalling was determined using immunoblot analysis.

Results

We identified MAMDC2 as a down‐regulated gene showing significant prognostic capability. Overexpression of MAMDC2 or treatment with MAMDC2‐containing culture medium significantly inhibited the cell proliferation of T‐47D cells. Furthermore, MAMDC2 expression reduced in vivo growth of T‐47D xenograft tumours. MAMDC2 may exert its growth‐inhibitory functions by attenuating the MAPK signalling pathway.

Conclusion

We report that MAMDC2 has a tumour‐suppressive role and, as a secretory protein, it might be useful as a biomarker for breast cancer treatment.

Functional relationship between p53 and RUNX proteins

RUNX genes belong to a three-membered family of transcription factors, which are well established as master regulators of development. Of them, aberrations in RUNX3 expression are frequently observed in human malignancies primarily due to epigenetic silencing, which is often overlooked. At the G1 phase of the cell cycle, RUNX3 regulates the restriction (R)-point, a mechanism that decides cell cycle entry. Deregulation at the R-point or loss of RUNX3 results in premature entry into S phase, leading to a proliferative advantage. Inactivation of Runx1 and Runx2 induce immortalization of mouse embryo fibroblast. As a consequence, RUNX loss induces pre-cancerous lesions independent of oncogene activation. p53 is the most extensively studied tumour suppressor. p53 plays an important role to prevent tumour progression but not tumour initiation. Therefore, upon oncogene activation, early inactivation of RUNX genes and subsequent mutation of p53 appear to result in tumour initiation and progression. Recently, transcription-independent DNA repairing roles of RUNX3 and p53 are emerging. Being evolutionarily old genes, it appears that the primordial function of p53 is to protect genome integrity, a function that likely extends to the RUNX gene as well. In this review, we examine the mechanism and sequence of actions of these tumour suppressors in detail.

AMPH1 functions as a tumour suppressor in ovarian cancer via the inactivation of PI3K/AKT pathway

AMPH1, an abundant protein in nerve terminals, plays a critical role in the recruitment of dynamin to sites of clathrin-mediated endocytosis. Recently, it is reported to be involved in breast cancer and lung cancer. However, the impact of AMPH1 on ovarian cancer is unclear. In this study, we used gain-of-function and loss-of-function methods to explore the role of AMPH1 in ovarian cancer cells. AMPH1 inhibited ovarian cancer cell growth and cell migration, and promoted caspase-3 activity, resulting in the increase of cell apoptosis. In xenograft mice model, AMPH1 prevented tumour progression. The anti-oncogene effects of AMPH1 on ovarian cancer might be partially due to the inhibition of PI3K/AKT signalling pathway after overexpression of AMPH1. Immunohistochemistry analysis showed that the staining of AMPH1 was remarkably reduced in ovarian cancer tissues compared with normal ovarian tissues. In conclusion, our study identifies AMPH1 as a tumour suppressor in ovarian cancer in vitro and in vivo. This is the first evidence that AMPH1 inhibited cell growth and migration, and induced apoptosis via the inactivation of PI3K/AKT signalling pathway on ovarian cancer, which may be used as an effective strategy.

The pVHL neglected functions, a tale of hypoxia-dependent and -independent regulations in cancer

The von Hippel–Lindau protein (pVHL) is a tumour suppressor mainly known for its role as master regulator of hypoxia-inducible factor (HIF) activity. Functional inactivation of pVHL is causative of the von Hippel–Lindau disease, an inherited predisposition to develop different cancers. Due to its impact on human health, pVHL has been widely studied in the last few decades. However, investigations mostly focus on its role in degrading HIFs, whereas alternative pVHL protein–protein interactions and functions are insistently surfacing in the literature. In this review, we analyse these almost neglected functions by dissecting specific conditions in which pVHL is proposed to have differential roles in promoting cancer. We reviewed its role in regulating phosphorylation as a number of works suggest pVHL to act as an inhibitor by either degrading or promoting downregulation of specific kinases. Further, we summarize hypoxia-dependent and -independent pVHL interactions with multiple protein partners and discuss their implications in tumorigenesis.

Emerging roles of long non-coding RNAs in the p53 network

Transcription factor p53 is activated in response to numerous stress stimuli in order to promote repair and survival or death of abnormal cells. For decades, regulatory mechanisms and downstream targets that execute the many biological functions of tumour suppressor p53 largely focused on the products of protein-coding genes. Recently, an entirely new class of molecules, termed long non-coding RNAs (lncRNAs), were discovered as key regulatory players in shaping p53 activity and biological outcomes. Many p53-regulated lncRNAs are now reported to either directly or indirectly intervene in p53-regulatory networks, generally in fine-tuning p53's tumour surveillance programme. Recent studies reveal that signals that converge upon p53 to regulate its activity, and molecules that implement downstream p53-response include both proteins and lncRNAs. In this review, we discuss the non-proteomic component of p53-regulatory networks, focusing on lncRNAs regulated by p53 and/or that regulate p53 activity, and their impact on biological outcomes.

Lauric Acid Modulates Cancer-Associated microRNA Expression and Inhibits the Growth of the Cancer Cell

BACKGROUND

microRNAs are known to regulate various protein-coding gene expression posttranscriptionally. Fatty acids are cell membrane constituents and are also known to influence the biological activities of the cells like signal transduction, growth and differentiation of the cells, apoptosis induction, and other physiological functions. In our experiments, we used lauric acid to analyse its effects on human cancerous cell lines.

OBJECTIVE

Our objective was to speculate the miRNA expression profile in lauric acid treated and untreated cancerous cell lines and further study the metabolic pathways of the targeted tumour suppressor and oncogenes.

METHODS

The KB cells and HepG2 cells were treated with lauric acid and miRNA was isolated and the expression of tumour suppressor and oncogenic miRNA was measured by quantitative PCR. The untreated cells were used as control. The metabolic pathways of the target tumour suppressor and oncogenes were examined by GeneMANIA software.

RESULTS

Interestingly, the lauric acid treatment suppresses the expression of oncogenic miRNA and significantly upregulated the expression of some tumour suppressor miRNAs. GeneMANIA metabolic pathway revealed that the upregulated tumour suppressor miRNAs regulate several cancer-associated pathways such as DNA damage, signal transduction p53 class mediator, stem cell differentiation, cell growth, cell cycle phase transition, apoptotic signalling pathway, cellular response to stress and radiation, etc. whereas oncogenic miRNAs regulate the cancer-associated pathway like cell cycle phase transition, apoptotic signalling pathway, cell growth, response to oxidative stress, immune response activating cell surface protein signalling pathway, cyclin-dependent protein kinase activity, epidermal growth factor receptor signalling pathways, etc. Conclusion: In our study, we found that lauric acid works as an anticancer agent by altering the expression of miRNAs.

Frequent methylation of the tumour suppressor miR-1258 targeting PDL1: implication in multiple myeloma-specific cytotoxicity and prognostification

miR-1258 is localised to the first intron of ZNF385B at chromosome 2q31.3. miR-1258 promoter methylation was studied in 147 samples including 10 normal buffy coat, eight normal bone marrow plasma cells, 16 human myeloma cell lines (HMCLs), 20 MGUS, 63 diagnostic myeloma, and 30 relapsed myeloma samples by methylation-specific PCR. In myeloma lines, miR-1258 methylation, verified by pyrosequencing, was detected in 62·5% HMCLs but not normal controls, and expression of miR-1258 correlated with that of ZNF385B. 5-Aza-2'-deoxycytidine resulted in promoter demethylation and ZNF385B/miR-1258 re-expression. Luciferase assay confirmed programmed cell death ligand-1 (PDL1) as a direct target of miR-1258. Over-expression of miR-1258 in completely methylated myeloma cells led to reduced cellular proliferation and enhanced apoptosis, hence a tumour suppressor role, in addition to repression of PDL1. In primary samples, miR-1258 methylation, with lower expression of miR-1258, was detected in 49·2% diagnostic myeloma, imparting an inferior PFS (P = 0·034) in addition to 50·0% relapsed myeloma but not MGUS. Therefore, miR-1258 is a tumour suppressor miRNA co-regulated with its host gene, and frequently hypermethylated in active myeloma instead of MGUS, hence acquired during myeloma progression. Methylation-mediated miR-1258 silencing led to overexpression of PDL1 and inferior PFS, implicating miR-1258 in the modulation of myeloma-specific cytotoxicity.

RASSF1A Tumour Suppressor: Target the Network for Effective Cancer Therapy

The RASSF1A tumour suppressor is a scaffold protein that is involved in cell signalling. Increasing evidence shows that this protein sits at the crossroad of a complex signalling network, which includes key regulators of cellular homeostasis, such as Ras, MST2/Hippo, p53, and death receptor pathways. The loss of expression of RASSF1A is one of the most common events in solid tumours and is usually caused by gene silencing through DNA methylation. Thus, re-expression of RASSF1A or therapeutic targeting of effector modules of its complex signalling network, is a promising avenue for treating several tumour types. Here, we review the main modules of the RASSF1A signalling network and the evidence for the effects of network deregulation in different cancer types. In particular, we summarise the epigenetic mechanism that mediates RASSF1A promoter methylation and the Hippo and RAF1 signalling modules. Finally, we discuss different strategies that are described for re-establishing RASSF1A function and how a multitargeting pathway approach selecting druggable nodes in this network could lead to new cancer treatments.

Chromatin protein PC4 is downregulated in breast cancer to promote disease progression: Implications of miR-29a

The human transcriptional coactivator PC4 has numerous roles to play in the cell. Other than its transcriptional coactivation function, it facilitates chromatin organization, DNA damage repair, viral DNA replication, etc. Although it was found to be an essential protein in vivo, the importance of this multifunctional protein in the regulation of different cellular pathways has not been investigated in details, particularly in oncogenesis. In this study, PC4 downregulation was observed in a significant proportion of mammary tissues obtained from Breast cancer patient samples as well as in a subset of highly invasive and metastatic Breast cancer patient-derived cell lines. We have identified a miRNA, miR-29a which potentially reduce the expression of PC4 both in RNA and protein level. This miR-29a was found to be indeed overexpressed in a substantial number of Breast cancer patient samples and cell lines as well, suggesting one of the key mechanisms of PC4 downregulation. Stable Knockdown of PC4 in MCF7 cells induced its migratory as well as invasive properties. Furthermore, in an orthotopic breast cancer mice model system; we have shown that reduced expression of PC4 enhances the tumorigenic potential substantially. Absence of PC4 led to the upregulation of several genes involved in Epithelial to Mesenchymal Transition (EMT), indicating the possible mechanism of uniform tumour progression in the orthotropic mice. Collectively these data establish the role of PC4 in tumour suppression.

Acidic pH derived from cancer cells as a double-edged knife modulates wound healing through DNA repair genes and autophagy

Wound healing is a sequester program that involves diverse cell signalling cascades. Notwithstanding, complete signal transduction pathways underpinning acidic milieu derived from cancer cells is not clear, yet. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, fluorescein diacetate/propidium iodide staining, and cell cycle flow cytometry revealed that acidic media decreased cell viability and cell number along with enhanced dead cells and S-phase arrest in normal fibroblasts. Notably, the trends of intracellular reactive oxygen species production and lactate dehydrogenase release significantly increased with time. It seems the downregulation of Klf4 is in part due to acidosis-induced DNA damage. It promoted cells towards S-phase arrest and diminished cell proliferation. Klf4 downregulation had a direct correlation with the P53 level while acidic microenvironment promotes cells towards cell death mechanisms including apoptosis and autophagy. Noteworthily, the unchanged levels of Rb and Mlh1 indicated in those genes had no dominant role in the repairing of DNA damage in fibroblasts treated with the acidic microenvironment. Therefore, cells owing to not entering to mitosis and accumulation of DNA damage were undergone cell death to preserve cell homeostasis. Since acidic media decreased the level of tumour suppressor and DNA repair genes and altered the normal survival pathways in fibroblasts, caution should be exercised to not lead to cancer rather than wound healing.

RN181 is a tumour suppressor in gastric cancer by regulation of the ERK/MAPK-cyclin D1/CDK4 pathway

RN181, a RING finger domain-containing protein, is an E3 ubiquitin ligase. However, its biological function and clinical significance in cancer biology are obscure. Here, we report that RN181 expression is significantly down-regulated in 165 tumour tissues of gastric carcinoma (GC) versus adjacent non-tumour tissues, and inversely associated with tumour differentiation, tumour size, clinical stage, and patient's overall survival. Alterations of RN181 expression in GC cells by retrovirus-transduced up-regulation and down-regulation demonstrated that RN181 functions as a tumour suppressor to inhibit growth of GC in both in vitro culture and in vivo animal models by decreasing tumour cell proliferation and increasing tumour cell apoptosis. Cell cycle analysis revealed that RN181 controls the cell cycle transition from G1 to S phase. Mechanistic studies demonstrated that RN181 inhibits ERK/MAPK signalling, thereby regulating the activity of cyclin D1-CDK4, and consequently controlling progression in the cell cycle from G1 to S phase. Restoring CDK4 in GC cells rescued the inhibitory phenotype produced by RN181 in vitro and in vivo, suggesting a dominant role of CDK4 in control of the tumour growth by RN181. Importantly, RN181 expression is inversely correlated with the expression of cyclin D1 and CDK4 in GC clinical samples, substantiating the role of the RN181-cyclin D1/CDK4 pathway in control of the tumour growth of GC. Our results provide new insights into the pathogenesis and development of GC and rationale for developing novel intervention strategies against GC by disruption of ERK/MAPK-cyclin D1/CDK4 signalling. In addition, RN181 may serve as a novel biomarker for predicting clinical outcome of GC. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Cadherin-11 is inactivated due to promoter methylation and functions in colorectal cancer as a tumour suppressor

Background: The cadherin-11 (CDH11, OB-cadherin) gene is a member of the cadherin family and is located on chromosome 16q22.1. Previous studies have revealed that cadherins play significant roles in the development of many human malignancies. Increasing evidence has identified CDH11 as a functional tumour suppressor, which is commonly silenced by promoter methylation, but the functions of this gene in colorectal cancer (CRC) have been unclear.

Methods: The CDH11 expression in primary CRC tissues and cell lines was investigated by qRT-PCR, RT-PCR and immunohistochemistry. The promoter methylation status of CDH11 was measured by methylation-specific PCR (MSP). Cell proliferation assay, colony formation assay, flow cytometry analysis, wound-healing assay, transwell assay and in vivo experiments were used to investigate the function of CDH11 in CRC. The mechanisms of CDH11 also were explored by western blots.

Results: Our study suggests that CDH11 downregulation in CRC due to its promoter methylation and induced cell cycle arrest in G0/G1 phase and apoptosis, suppressing tumor cell proliferation, colony formation, migration and invasion by affecting the NF-kB signaling pathway.

Conclusion: Overall, CDH11 may be considered as a functional tumour suppressor gene (TSG) in CRC, CDH11 has the potential to serve as a valuable prognostic marker for colorectal cancer.

CXXC5: A novel regulator and coordinator of TGF-β, BMP and Wnt signaling

CXXC5 is a member of the CXXC-type zinc-finger protein family. Proteins in this family play a pivotal role in epigenetic regulation by binding to unmethylated CpG islands in gene promoters through their characteristic CXXC domain. CXXC5 is a short protein (322 amino acids in length) that does not have any catalytic domain, but is able to bind to DNA and act as a transcription factor and epigenetic factor through protein-protein interactions. Intriguingly, increasing evidence indicates that expression of the CXXC5 gene is controlled by multiple signaling pathways and a variety of transcription factors, positioning CXXC5 as an important signal integrator. In addition, CXXC5 is capable of regulating various signal transduction processes, including the TGF-β, Wnt and ATM-p53 pathways, thereby acting as a novel and crucial signaling coordinator. CXXC5 plays an important role in embryonic development and adult tissue homeostasis by regulating cell proliferation, differentiation and apoptosis. In keeping with these functions, aberrant expression or altered activity of CXXC5 has been shown to be involved in several human diseases including tumourigenesis. This review summarizes the current understanding of CXXC5 as a transcription factor and signaling regulator and coordinator.

MicroRNA-148a inhibits cell proliferation and cell cycle progression in lung adenocarcinoma via directly targeting transcription factor E2F3

MicroRNAs (miRs) serve important roles in various human cancers, including lung adenocarcinoma. Exploring the function and regulatory mechanism of miRs underlying lung adenocarcinoma progression may contribute to identifying novel therapeutic targets and candidates. The present study aimed to examine miR-148a expression and investigate the molecular mechanisms of miR-148a in lung adenocarcinomas. The data from the current study indicated that miR-148a was significantly downregulated in lung adenocarcinoma tissues and cell lines, and low miR-148a expression was significantly associated with advanced Tumor, Node, Metastasis stages and lymph node metastasis, as well as the shorter survival time of patients. Increased miR-148a expression markedly decreased the cell proliferation, colony formation and cell cycle progression of H23 and H1975 cells. Transcription factor E2F3 (E2F3) was identified as a target of miR-148a in H23 and H1975 cells. The expression of E2F3 was negatively mediated by miR-148a in H23 and H1975 cells. In addition, E2F3 was significantly upregulated in lung adenocarcinoma tissues and cell lines, and the expression of miR-148a was inversely correlated with E2F3 expression in lung adenocarcinoma tissues. Additional experiments demonstrated that increased E2F3 expression counteracted the inhibitory effects on lung adenocarcinoma cells caused by miR-148a overexpression. In summary, the findings of the current study suggest that miR-148a may have suppressive effects on the proliferation of lung adenocarcinoma cells at least in part through directly targeting E2F3. Therefore, miR-148a may be used as a potential candidate for the treatment of lung adenocarcinoma.

Downregulation of DHRS9 is associated with poor prognosis in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) has a high potential for local invasion and nodal metastasis. Therefore, early detection and elucidation of the detailed molecular mechanisms underlying OSCC are essential. Dehydrogenase/reductase member 9 (DHRS9) is downregulated in recurrent OSCC. Although DHRS9 is reported to act as a tumour suppressor in several malignancies, its expression in OSCC cells is unknown. In this study, we examined DHRS9 expression immunohistochemically in specimens from a sample of 98 OSCC patients. Reduced DHRS9 expression was observed in 68 of 98 patients (69.4%) with OSCC. A significant association was found between low DHRS9 expression and local progression (T factor) (p = 0.0135). Furthermore, patients with low DHRS9 expression had a significantly poorer prognosis than those with high DHRS9 expression (p = 0.0443). In multivariate analysis using the Cox proportional hazards model, decreased DHRS9 expression strongly correlated with worse prognosis. The study findings suggest that DHRS9 might be a useful diagnostic and prognostic marker for OSCC.

CASC2: An emerging tumour-suppressing long noncoding RNA in human cancers and melanoma

Deregulation of long noncoding RNAs (lncRNAs) has been implicated in tumourigenesis. Cancer Susceptibility Candidate 2 (CASC2) is a lncRNA downregulated in multiple cancer types, including endometrial, lung, gastric and colorectal cancers. CASC2 functions as a tumour-suppressive lncRNA though multiple mechanisms, such as sequestration of oncogenic microRNAs and repression of Wnt/β-catenin signalling. Pertinent to clinical practice, the use of CASC2 as a prognostic marker has been demonstrated in sporadic studies. These findings suggested that CASC2 might play an important role in human cancers and melanoma. More efforts are warranted to examine the function role of CASC2 in other cancer types. Further validation is also needed to promote its development to be a clinically utilizable prognostic biomarker.

A HIF-LIMD1 negative feedback mechanism mitigates the pro-tumorigenic effects of hypoxia

The adaptive cellular response to low oxygen tensions is mediated by the hypoxia-inducible factors (HIFs), a family of heterodimeric transcription factors composed of HIF-α and HIF-β subunits. Prolonged HIF expression is a key contributor to cellular transformation, tumorigenesis and metastasis. As such, HIF degradation under hypoxic conditions is an essential homeostatic and tumour-suppressive mechanism. LIMD1 complexes with PHD2 and VHL in physiological oxygen levels (normoxia) to facilitate proteasomal degradation of the HIF-α subunit. Here, we identify LIMD1 as a HIF-1 target gene, which mediates a previously uncharacterised, negative regulatory feedback mechanism for hypoxic HIF-α degradation by modulating PHD2-LIMD1-VHL complex formation. Hypoxic induction of LIMD1 expression results in increased HIF-α protein degradation, inhibiting HIF-1 target gene expression, tumour growth and vascularisation. Furthermore, we report that copy number variation at the LIMD1 locus occurs in 47.1% of lung adenocarcinoma patients, correlates with enhanced expression of a HIF target gene signature and is a negative prognostic indicator. Taken together, our data open a new field of research into the aetiology, diagnosis and prognosis of LIMD1-negative lung cancers.

MicroRNA-124 inhibits cell proliferation, invasion and migration by targeting CAV1 in bladder cancer

MicroRNAs (miRs) may have promotive or suppressive roles in various human cancers types, but the molecular mechanisms underlying the role of miR-124 in bladder cancer (BC) progression have remained largely elusive. In the present study, it was observed that miR-124 was significantly downregulated in BC tissues compared with that in adjacent non-neoplastic tissues. Furthermore, its expression was also reduced in several human BC cell lines (T24, HT-1376 and 5637) compared with that in the normal bladder epithelial SV-HUC-1 cell line. A low expression of miR-124 in BC patients was significantly associated with advanced malignancy and a poor prognosis. Caveolin 1 (CAV1) was identified as a novel target gene of miR-124, and the expression of CAV1 was negatively regulated by miR-124 in T24 cells. Furthermore, CAV1 was identified to be significantly upregulated in BC tissues and cell lines, and a negative correlation was observed between the expression of miR-124 and CAV1 in BC tissues. Furthermore, restoration of miR-124 expression significantly inhibited the proliferation, migration and invasion of T24 cells, and these effects were impaired following overexpression of CAV1. Taken together, the present results demonstrate that miR-124 has a suppressive role in the proliferation, migration and invasion of BC cells by targeting CAV1, which suggests that miR-124 is a potential therapeutic candidate for BC.

FOXP3 and miR-155 cooperate to control the invasive potential of human breast cancer cells by down regulating ZEB2 independently of ZEB1

Control of oncogenes, including ZEB1 and ZEB2, is a major checkpoint for preventing cancer, and loss of this control contributes to many cancers, including breast cancer. Thus tumour suppressors, such as FOXP3, which is mutated or lost in many cancer tissues, play an important role in maintaining normal tissue homeostasis. Here we show for the first time that ZEB2 is selectively down regulated by FOXP3 and also by the FOXP3 induced microRNA, miR-155. Interestingly, neither FOXP3 nor miR-155 directly altered the expression of ZEB1. In breast cancer cells repression of ZEB2, independently of ZEB1, resulted in reduced expression of a mesenchymal marker, Vimentin and reduced invasion. However, there was no de-repression of E-cadherin and migration was enhanced. Small interfering RNAs targeting ZEB2 suggest that this was a direct effect of ZEB2 and not FOXP3/miR-155. In normal human mammary epithelial cells, depletion of endogenous FOXP3 resulted in de-repression of ZEB2, accompanied by upregulated expression of vimentin, increased E-cadherin expression and cell morphological changes. We suggest that FOXP3 may help maintain normal breast epithelial characteristics through regulation of ZEB2, and loss of FOXP3 in breast cancer cells results in deregulation of ZEB2.

The Long Non-Coding RNA RP5-1024C24.1 and Its Associated-Gene MPPED2 Are Down-Regulated in Human Thyroid Neoplasias and Act as Tumour Suppressors

Background: Well-differentiated papillary thyroid carcinoma (PTC) represents the thyroid neoplasia with the highest incidence. Long non-coding RNAs (lncRNAs) have been found deregulated in several human carcinomas, and hence, proposed as potential diagnostic and prognostic markers. Therefore, the aim of our study was to investigate their role in thyroid carcinogenesis. Methods: We analysed the lncRNA expression profile of 12 PTC and four normal thyroid tissues through a lncRNA microarray. Results: We identified 669 up- and 2470 down-regulated lncRNAs with a fold change >2. Among them, we focused on the down-regulated RP5-1024C24.1 located in an antisense position with respect to the MPPED2 gene which codes for a metallophosphoesterase with tumour suppressor activity. Both these genes are down-regulated in benign and malignant thyroid neoplasias. The restoration of RP5-1024C24.1 expression in thyroid carcinoma cell lines reduced cell proliferation and migration by modulating the PTEN/Akt pathway. Inhibition of thyroid carcinoma cell growth and cell migration ability was also achieved by the MPPED2 restoration. Interestingly, RP5-1024C24.1 over-expression is able to increase MPPED2 expression. Conclusions: Taken together, these results demonstrate that RP5-1024C24.1 and MPPED2 might be considered as novel tumour suppressor genes whose loss of expression contributes to thyroid carcinogenesis.

Inhibition of breast cancer cell growth by the combination of clofarabine and sulforaphane involves epigenetically mediated CDKN2A upregulation

Many antineoplastic nucleoside analogue-based combinatorial strategies focused on remodelling aberrant DNA methylation patterns have been developed. The number of studies demonstrate high efficacy of bioactive phytochemicals in support of conventional chemotherapy. Our recent discoveries of the epigenetic effects of clofarabine (2'-deoxyadenosine analogue, antileukaemic drug) and clofarabine-based combinations with dietary bioactive compounds in breast cancer cells led us to look for more DNA methylation targets of these cancer-preventive agents. In the present study, using methylation-sensitive restriction analysis (MSRA) and qPCR, we showed that clofarabine in combination with sulforaphane, a phytochemical from cruciferous vegetables, significantly reactivates DNA methylation-silenced CDKN2A tumour suppressor and inhibits cancer cell growth at a non-invasive breast cancer stage.