Increased seroreactivity to glioma-expressed antigen 2 in brain tumor patients under radiation

N6-methyladenosine demethylase ALKBH5 suppresses colorectal cancer progression potentially by decreasing PHF20 mRNA methylation

BACKGROUND

As the most widespread mRNAs modification, N6-methyladenosine (m6 A) is dynamically and reversibly modulated by methyltransferases and demethylases. ALKBH5 is a major demethylase, and plays vital roles in the progression of cancers. However, the role and mechanisms of ALKBH5 in colorectal cancer (CRC) is unclear.

RESULTS

Herein, we discovered that in CRC, downregulated ALKBH5 was closely related to poor prognosis of CRC patients. Functionally, our results demonstrated that knockdown of ALKBH5 enhanced the proliferation, migration and invasion of LOVO and RKO in vitro, while overexpression of ALKBH5 inhibited the functions of these cells. The results also demonstrated that knockdown of ALKBH5 promoted subcutaneous tumorigenesis of LOVO in vivo, while overexpression of ALKBH5 suppressed this ability. Mechanistically, results from joint analyses of MeRIP-seq and RNA-seq indicated that PHF20 mRNA was a key molecule that was regulated by ALKBH5-mediated m6 A modification. Further experiments indicated that ALKBH5 may inhibit stability of PHF20 mRNA by removing the m6 A modification of PHF20 mRNA 3'UTR.

CONCLUSIONS

ALKBH5 suppresses CRC progression by decreasing PHF20 mRNA methylation. ALKBH5-mediated m6 A modification of PHF20 mRNA can serve as a hopeful strategy for the intervention and treatment of CRC.

Methyl-lysine readers PHF20 and PHF20L1 define two distinct gene expression-regulating NSL complexes

The methyl-lysine readers plant homeodomain finger protein 20 (PHF20) and its homolog PHF20-like protein 1 (PHF20L1) are known components of the nonspecific lethal (NSL) complex that regulates gene expression through its histone acetyltransferase activity. In the current model, both PHF homologs coexist in the same NSL complex, although this was not formally tested; nor have the functions of PHF20 and PHF20L1 regarding NSL complex integrity and transcriptional regulation been investigated. Here, we perform an in-depth biochemical and functional characterization of PHF20 and PHF20L1 in the context of the NSL complex. Using mass spectrometry, genome-wide chromatin analysis, and protein-domain mapping, we identify the existence of two distinct NSL complexes that exclusively contain either PHF20 or PHF20L1. We show that the C-terminal domains of PHF20 and PHF20L1 are essential for complex formation with NSL, and the Tudor 2 domains are required for chromatin binding. The genome-wide chromatin landscape of PHF20-PHF20L1 shows that these proteins bind mostly to the same genomic regions, at promoters of highly expressed/housekeeping genes. Yet, deletion of PHF20 and PHF20L1 does not abrogate gene expression or impact the recruitment of the NSL complex to those target gene promoters, suggesting the existence of an alternative mechanism that compensates for the transcription of genes whose sustained expression is important for critical cellular functions. This work shifts the current paradigm and lays the foundation for studies on the differential roles of PHF20 and PHF20L1 in regulating NSL complex activity in physiological and diseases states.

The Autoantibodies against Tumor-Associated Antigens as Potential Blood-Based Biomarkers in Thyroid Neoplasia: Rationales, Opportunities and Challenges

The Autoantibodies targeting Tumor-Associated Antigens (TAA-AAbs) emerge as a result of a variety of tumor-related immunogenic stimuli and may be regarded as the eyewitnesses to the anti-tumor immune response. TAA-AAbs may be readily detected in peripheral blood to unveil the presence of a particular TAA-expressing tumor, and a fair number of TAAs eliciting the tumor-associated autoantibody response have been identified. The potential of TAA-AAbs as tumor biomarkers has been extensively studied in many human malignancies with a major influence on public health; however, tumors of the endocrine system, and, in particular, the well-differentiated follicular cell-derived thyroid neoplasms, remain understudied in this context. This review provides a detailed perspective on and legitimate rationales for the potential use of TAA-AAbs in thyroid neoplasia, with particular reference to the already established diagnostic implications of the TAA-AAbs in human cancer, to the windows for improvement and diagnostic niches in the current workup strategies in nodular thyroid disease and differentiated thyroid cancer that TAA-AAbs may successfully occupy, as well as to the proof-of-concept studies demonstrating the usefulness of TAA-AAbs in thyroid oncology, particularly for the pre-surgical discrimination between tumors of different malignant potential in the context of the indeterminate results of the fine-needle aspiration cytology.

PHF20 Readers Link Methylation of Histone H3K4 and p53 with H4K16 Acetylation

PHF20 is a core component of the lysine acetyltransferase complex MOF (male absent on the first)-NSL (non-specific lethal) that generates the major epigenetic mark H4K16ac and is necessary for transcriptional regulation and DNA repair. The role of PHF20 in the complex remains elusive. Here, we report on functional coupling between methylation readers in PHF20. We show that the plant homeodomain (PHD) finger of PHF20 recognizes dimethylated lysine 4 of histone H3 (H3K4me2) and represents an example of a native reader that selects for this modification. Biochemical and structural analyses help to explain this selectivity and the preference of Tudor2, another reader in PHF20, for dimethylated p53. Binding of the PHD finger to H3K4me2 is required for histone acetylation, accumulation of PHF20 at target genes, and transcriptional activation. Together, our findings establish a unique PHF20-mediated link between MOF histone acetyltransferase (HAT), p53, and H3K4me2, and suggest a model for rapid spreading of H4K16ac-enriched open chromatin.

Recurrent glioma clinical trial, CheckMate-143: the game is not over yet

Glioblastoma (GBM) is the most common, and aggressive, primary brain tumor in adults. With a median patient survival of less than two years, GBM represents one of the biggest therapeutic challenges of the modern era. Even with the best available treatment, recurrence rates are nearly 100% and therapeutic options at the time of relapse are extremely limited. Nivolumab, an anti-programmed cell death-1 (PD-1) monoclonal antibody, has provided significant clinical benefits in the treatment of various advanced cancers and represented a promising therapy for primary and recurrent GBM. CheckMate 143 (NCT 02017717) was the first large randomized clinical trial of PD pathway inhibition in the setting of GBM, including a comparison of nivolumab and the anti-VEGF antibody, bevacizumab, in the treatment of recurrent disease. However, preliminary results, recently announced in a WFNOS 2017 abstract, demonstrated a failure of nivolumab to prolong overall survival of patients with recurrent GBM, and this arm of the trial was prematurely closed. In this review, we discuss the basic concepts underlying the rational to target PD pathway in GBM, address implications of using immune checkpoint inhibitors in central nervous system malignancies, provide a rationale for possible reasons contributing to the failure of nivolumab to prolong survival in patients with recurrent disease, and analyze the future role of immune checkpoint inhibitors in the treatment of GBM.

Whole blood transcriptome correlates with treatment response in nasopharyngeal carcinoma

Background

Treatment protocols for nasopharyngeal carcinoma (NPC) developed in the past decade have significantly improved patient survival. In most NPC patients, however, the disease is diagnosed at late stages, and for some patients treatment response is less than optimal. This investigation has two aims: to identify a blood-based gene-expression signature that differentiates NPC from other medical conditions and from controls and to identify a biomarker signature that correlates with NPC treatment response.

Methods

RNA was isolated from peripheral whole blood samples (2 x 10 ml) collected from NPC patients/controls (EDTA vacutainer). Gene expression patterns from 99 samples (66 NPC; 33 controls) were assessed using the Affymetrix array. We also collected expression data from 447 patients with other cancers (201 patients) and non-cancer conditions (246 patients). Multivariate logistic regression analysis was used to obtain biomarker signatures differentiating NPC samples from controls and other diseases. Differences were also analysed within a subset (n = 28) of a pre-intervention case cohort of patients whom we followed post-treatment.

Results

A blood-based gene expression signature composed of three genes — LDLRAP1, PHF20, and LUC7L3 — is able to differentiate NPC from various other diseases and from unaffected controls with significant accuracy (area under the receiver operating characteristic curve of over 0·90). By subdividing our NPC cohort according to the degree of patient response to treatment we have been able to identify a blood gene signature that may be able to guide the selection of treatment.

Conclusion

We have identified a blood-based gene signature that accurately distinguished NPC patients from controls and from patients with other diseases. The genes in the signature, LDLRAP1, PHF20, and LUC7L3, are known to be involved in carcinoma of the head and neck, tumour-associated antigens, and/or cellular signalling. We have also identified blood-based biomarkers that are (potentially) able to predict those patients who are more likely to respond to treatment for NPC. These findings have significant clinical implications for optimizing NPC therapy.

PHF20 is an effector protein of p53 double lysine methylation that stabilizes and activates p53

PHF20 is a multidomain protein and subunit of a lysine acetyltransferase complex that acetylates histone H4 and p53 but whose function is unclear. Using biochemical, biophysical and cellular approaches, we determined that PHF20 is a direct regulator of p53. A Tudor domain in PHF20 recognized p53 dimethylated at Lys370 or Lys382 and a homodimeric form of this Tudor domain could associate with the two dimethylated sites on p53 with enhanced affinity, indicating a multivalent interaction. Association with PHF20 promotes stabilization and activation of p53 by diminishing Mdm2-mediated p53 ubiquitylation and degradation. PHF20 contributes to upregulation of p53 in response to DNA damage, and ectopic expression of PHF20 in different cell lines leads to phenotypic changes that are hallmarks of p53 activation. Overall our work establishes that PHF20 functions as an effector of p53 methylation that stabilizes and activates p53.

Preliminary study of thyroid and colon cancers-associated antigens and their cognate autoantibodies as potential cancer biomarkers

BACKGROUND

Autoantibodies, which are produced against tumor-associated antigens, are potential tumor markers and attract a growing interest for cancer detection, differential diagnostics and prognosis.

OBJECTIVE

To evaluate the diagnostic significance of 40 antigens identified by immunoscreening of cDNA libraries from thyroid and colon cancers by allogenic screening with different tumor types patients' sera.

METHOD

Plaque-spot serological assay.

RESULTS

Increased frequency of antibody response in sera of cancer patients compared with that of healthy donors was shown toward 14 antigens, 8 of which (CG016, BTN3A3, FKBP4, XRCC4, TSGA2, ACTR1A, FXYD3 and CTSH) have revealed exclusively cancer-related serological profile.

CONCLUSION

Allogenic screening of 40 SEREX-antigens with sera from cancer patients and healthy donors allowed us to reveal 14 antigens with potential diagnostic significance. These antigens and their cognate autoantibodies could be considered as valuable targets for further analysis as potential cancer biomarkers.

Glioma stem cell research for the development of immunotherapy

Malignant gliomas are characterized by its invasiveness and dissemination, resulting in frequent tumor recurrence after surgical resection and/or conventional chemotherapy and radiation therapy. Various strategies of active and passive immunotherapy in developing stages have shown promise to increase patient survival time with little severe side effects. In recent years, glioma stem cells had been isolated from patient tumor specimens. Biochemical and biological characterization of these cancer initiating cells implicated their critical roles in cancer growth, malignancy and resistance to conventional treatments. In this chapter, we review recent research progress in targeting brain cancer using neural stem cells delivered cytotoxic factors and immune regulation factor, dendritic cell based vaccination, with special emphasis on targeting glioma stem cells. We present evidence supporting the notion that glioma stem cells may be preferred therapeutic targets not only for conventional therapies, but also for immunotherapies. Future progress in glioma stem cell research may fundamentally improve the prospect of malignant glioma treatments.

Loss of the methyl lysine effector protein PHF20 impacts the expression of genes regulated by the lysine acetyltransferase MOF

In epigenetic signaling pathways, histone tails are heavily modified, resulting in the recruitment of effector molecules that can influence transcription. One such molecule, plant homeodomain finger protein 20 (PHF20), uses a Tudor domain to read dimethyl lysine residues and is a known component of the MOF (male absent on the first) histone acetyltransferase protein complex, suggesting it plays a role in the cross-talk between lysine methylation and histone acetylation. We sought to investigate the biological role of PHF20 by generating a knockout mouse. Without PHF20, mice die shortly after birth and display a wide variety of phenotypes within the skeletal and hematopoietic systems. Mechanistically, PHF20 is not required for maintaining the global H4K16 acetylation levels or locus specific histone acetylation but instead works downstream in transcriptional regulation of MOF target genes.

Intratumoral injection of interleukin-2 augments the local and abscopal effects of radiotherapy in murine rectal cancer

Recent studies have suggested that tumor shrinkage in response to radiotherapy (RT) is greatly dependent on the host immune response. A Balb/c mouse model of simultaneous subcutaneous tumor and liver metastasis of Colon26 was prepared and, after irradiation of the subcutaneous tumor (2 Gy × 5 day × 2 cycles), interleukin-2 (IL-2) (2 × 10(4) U) was injected intra-tumorally, and the fate of both the subcutaneous tumor and liver metastatic lesions was evaluated. Intratumoral injection of IL-2 greatly enhanced the anti-tumor effects of RT and completely eradicated the established subcutaneous tumor. Interestingly, although RT was given locally to the subcutaneous tumor, liver metastasis formation was also inhibited in mice receiving only local RT. More impressively, the combination of RT + IL-2 completely inhibited liver metastasis formation. Splenocytes in mice receiving RT + IL-2 contained a higher percentage of CD4(+) T cells, but lower percentages of CD4(+)CD25(+) regulatory T cells and CD11b(+) Gr-1(+) myeloid-derived suppressor cells. Immunohistochemical investigation of human rectal cancer revealed that the density of CD8(+) cells infiltrating into irradiated rectal tumor was positively associated with a lower frequency of distant metastasis as well as histological response grade. Local administration of IL-2 not only enhances shrinkage of the irradiated tumor itself, but can also suppress the development of distant metastasis located outside the RT field, possibly though the induction of a systemic T cell response. Augmentation of T-cell-mediated antitumor immunity during RT might be critical for improvement of the clinical efficacy of neoadjuvant RT for the treatment of advanced rectal cancer.

Antigen-specific T-cell response from dendritic cell vaccination using cancer stem-like cell-associated antigens

Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor, with current treatment remaining palliative. Immunotherapies harness the body's own immune system to target cancers and could overcome the limitations of conventional treatments. One active immunotherapy strategy uses dendritic cell (DC)-based vaccination to initiate T-cell-mediated antitumor immunity. It has been proposed that cancer stem-like cells (CSCs) may play a key role in cancer initiation, progression, and resistance to current treatments. However, whether using human CSC antigens may improve the antitumor effect of DC vaccination against human cancer is unclear. In this study, we explored the suitability of CSCs as sources of antigens for DC vaccination again human GBM, with the aim of achieving CSC-targeting and enhanced antitumor immunity. We found that CSCs express high levels of tumor-associated antigens as well as major histocompatibility complex molecules. Furthermore, DC vaccination using CSC antigens elicited antigen-specific T-cell responses against CSCs. DC vaccination-induced interferon-gamma production is positively correlated with the number of antigen-specific T cells generated. Finally, using a 9L CSC brain tumor model, we demonstrate that vaccination with DCs loaded with 9L CSCs, but not daughter cells or conventionally cultured 9L cells, induced cytotoxic T lymphocytes (CTLs) against CSCs, and prolonged survival in animals bearing 9L CSC tumors. Understanding how immunization with CSCs generates superior antitumor immunity may accelerate development of CSC-specific immunotherapies and cancer vaccines.

Identifying autoantibody signatures in cancer: a promising challenge

Biomarkers that show high sensitivity and specificity are needed for the early diagnosis and prognosis of cancer. An immune response to cancer is elicited in humans, as demonstrated, in part, by the identification of autoantibodies against a number of tumor-associated antigen (TAAs) in sera from patients with different types of cancer. Identification of TAAs and their cognate autoantibodies is a promising strategy for the discovery of relevant biomarkers. During the past few years, three proteomic approaches, including serological identification of antigens by recombinant expression cloning (SEREX), serological proteome analysis (SERPA) and, more recently, protein microarrays, have been the dominant strategies used to identify TAAs and their cognate autoantibodies. In this review, we aim to describe the advantages, drawbacks and recent improvements of these approaches for the study of humoral responses. Finally, we discuss the definition of autoantibody signatures to improve sensitivity for the development of clinically relevant tests.