Expression and clinical significance of COMPASS family of histone methyltransferases in clear cell renal cell carcinoma

A Pan-Cancer Study of KMT2 Family as Therapeutic Targets in Cancer

Objective

Exome sequencing studies have shown that the histone-lysine N-methyltransferase 2 (KMT2) gene is one of the most commonly mutated genes in a range of human malignancies and is linked to some of the most common and deadly solid tumors. However, the connection between this gene family's function and tumor type, immunological subtype, and molecular subtype dependency is still unknown.

Methods

We examine the expression patterns of the histone-lysine N-methyltransferase 2 (KMT2) gene, as well as their relationship to patient survival. We also used a pan-cancer analysis to link their function to immunological subtypes, the tumor microenvironment, and treatment sensitivity.

Results

Using the TCGA pan-cancer data, researchers looked at and examined KMT2 expression patterns and their links to patient survival and the tumor microenvironment in 33 cancer types. The expression of the KMT2 family changes significantly across and within cancer types, indicating significant inter- and intracancer heterogeneity. Patients' overall survival was often linked to the expression of KMT2 family members. However, the direction of the link differed depending on the KMT2 isoform and cancer type studied. Notably, in all cancer types examined, nearly all KMT2 family members were substantially linked with overall survival in patients with renal clear cell carcinoma (KIRC). Furthermore, all KMT2 genes have a strong relationship with immune infiltrate subtypes, as well as varying degrees of stromal cell infiltration and tumor cell stemness. Finally, we discovered that higher expression of KMT2s, particularly KMT2F and KMT2G, was linked to greater chemotherapeutic sensitivity in several cell lines.

Conclusions

The necessity to investigate each KMT2 member as a distinct entity inside each particular cancer type is highlighted by our comprehensive investigation of KMT2 gene expression and its relationship with immune infiltrates, tumor microenvironment, and cancer patient outcomes. Our research also confirmed the identification of KMT2 as a potential therapeutic target in cancer, but further laboratory testing is required.

Analyzing the impact of CFP1 mutational landscape on epigenetic signaling

CXXC Zinc finger protein 1 (CFP1) is a multitasking protein playing essential roles during various developmental processes. Its ability to interact with several proteins contribute to several epigenetic events. Here, we review CFP1's functions and its impact on DNA methylation and the post-translational modification of histone proteins such as lysine acetylation and methylation. We will also discuss the potential role of CFP1 in carcinogenesis and the impact of the mutations identified in patients suffering from various cancers.

Histone H3K4 Methyltransferases as Targets for Drug-Resistant Cancers

The KMT2 (MLL) family of proteins, including the major histone H3K4 methyltransferase found in mammals, exists as large complexes with common subunit proteins and exhibits enzymatic activity. SMYD, another H3K4 methyltransferase, and SET7/9 proteins catalyze the methylation of several non-histone targets, in addition to histone H3K4 residues. Despite these structural and functional commonalities, H3K4 methyltransferase proteins have specificity for their target genes and play a role in the development of various cancers as well as in drug resistance. In this review, we examine the overall role of histone H3K4 methyltransferase in the development of various cancers and in the progression of drug resistance. Compounds that inhibit protein-protein interactions between KMT2 family proteins and their common subunits or the activity of SMYD and SET7/9 are continuously being developed for the treatment of acute leukemia, triple-negative breast cancer, and castration-resistant prostate cancer. These H3K4 methyltransferase inhibitors, either alone or in combination with other drugs, are expected to play a role in overcoming drug resistance in leukemia and various solid cancers.

Aberrant Activity of Histone-Lysine N-Methyltransferase 2 (KMT2) Complexes in Oncogenesis

KMT2 (histone-lysine N-methyltransferase subclass 2) complexes methylate lysine 4 on the histone H3 tail at gene promoters and gene enhancers and, thus, control the process of gene transcription. These complexes not only play an essential role in normal development but have also been described as involved in the aberrant growth of tissues. KMT2 mutations resulting from the rearrangements of the KMT2A (MLL1) gene at 11q23 are associated with pediatric mixed-lineage leukemias, and recent studies demonstrate that KMT2 genes are frequently mutated in many types of human cancers. Moreover, other components of the KMT2 complexes have been reported to contribute to oncogenesis. This review summarizes the recent advances in our knowledge of the role of KMT2 complexes in cell transformation. In addition, it discusses the therapeutic targeting of different components of the KMT2 complexes.

Expression profile of H3K4 demethylases with their clinical and pathological correlation in patients with clear cell renal cell carcinoma

OBJECTIVE

Clear cell renal cell carcinoma (ccRCC) is one of the deadly diseases with poor metastatic disease prognosis. There is an urgent need to explore the potential molecular markers which can improve the prognosis of the disease. Histone demethylases have emerged as a powerful tool for cancer prognosis and therapeutics during the last decade. The implications of demethylases of histone 3 lysine 4 (H3K4) in ccRCC are however unrevealed. We therefore evaluated the expression of H3K4 demethylases in ccRCC, with emphasis on their clinical significance as a prognostic marker.

METHODS

Total 50 histopathological confirmed cases of ccRCC were enrolled in the study. The expression of seven H3K4 demethylases was determined by Real-Time PCR using gene specific primers and correlated with tumor stage, grade and metastasis. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the prognostic significance of H3K4 demethylases.

RESULTS

The median age of the patients was 54 years with predominance of male patients by 2.6-fold. Among seven genes viz FBXL10, LSD1, LSD2, KDM5A, KDM5B, KDM5C and KDM5D analyzed, LSD2 was found to be significantly associated with tumor stage and metastasis. The optimal cut-off value for LSD2 was 3.2 as calculated from ROC curve analysis for metastasis as well as TNM stage with area under curve of 0.74 and 0.78 respectively. In addition, LSD2 expression showed significant positive correlation with LSD1 expression in tumor metastasis.

CONCLUSION

The expression of LSD2 was associated with higher TNM stage and metastasis of the tumor and thus, might serve as a useful marker for ccRCC progression.

Therapeutic Targets in Telomerase and Telomere Biology of Cancers

Telomeres play an important role to conserve genomic integrity by protecting the ends of chromosomes in normal cells. Since, their progressive shortening during successive cell division which lead to chromosomal instability. Notably, telomere length is perpetuated by telomerase in large majority of cancers, thereby ensure indefinite cell proliferation-a hallmark of cancer-and this unique feature has provided telomerase as the preferred target for drug development in cancer therapeutics. Cancer cells have acquired the potential to have telomere length maintenance by telomerase activation- up-regulation of hTERT gene expression in tumor cells is synchronized by multiple genetic and epigenetic modification mechanisms viz hTERT structural variants, hTERT promoter mutation and epigenetic modifications through hTERT promoter methylation which have been implicated in various cancers initiation and progression. In view of these facts, strategies have been made to target the underlining molecular mechanisms involved in telomerase reactivation as well as of telomere structure with special reference to distortion of sheltrin proteins. This review is focussed on extensive understanding of telomere and telomerase biology. which will provide indispensable informations for enhancing the efficiency of rational anticancer drug design. However, there is also an urgent need for better understanding of cell signalling pathways for alternative lengthening of telomere which is present in telomerase negative cancer for therapeutic targets.

EMT transcription factor ZEB1 alters the epigenetic landscape of colorectal cancer cells

Epigenetic deregulation remarkably triggers mechanisms associated with tumor aggressiveness like epithelial-mesenchymal transition (EMT). Since EMT is a highly complex, but also reversible event, epigenetic processes such as DNA methylation or chromatin alterations must be involved in its regulation. It was recently described that loss of the cell cycle regulator p21 was associated with a gain in EMT characteristics and an upregulation of the master EMT transcription factor ZEB1. In this study, in silico analysis was performed in combination with different in vitro and in vivo techniques to identify and verify novel epigenetic targets of ZEB1, and to proof the direct transcriptional regulation of SETD1B by ZEB1. The chorioallantoic-membrane assay served as an in vivo model to analyze the ZEB1/SETD1B interaction. Bioinformatical analysis of CRC patient data was used to examine the ZEB1/SETD1B network under clinical conditions and the ZEB1/SETD1B network was modeled under physiological and pathological conditions. Thus, we identified a self-reinforcing loop for ZEB1 expression and found that the SETD1B associated active chromatin mark H3K4me3 was enriched at the ZEB1 promoter in EMT cells. Moreover, clinical evaluation of CRC patient data showed that the simultaneous high expression of ZEB1 and SETD1B was correlated with the worst prognosis. Here we report that the expression of chromatin modifiers is remarkably dysregulated in EMT cells. SETD1B was identified as a new ZEB1 target in vitro and in vivo. Our study demonstrates a novel example of an activator role of ZEB1 for the epigenetic landscape in colorectal tumor cells.

Gene fusion analysis in renal cell carcinoma by FusionPlex RNA-sequencing and correlations of molecular findings with clinicopathological features

Translocation renal cell carcinoma (tRCC) affects younger patients and often presents as advanced disease. Accurate diagnosis is required to guide clinical management. Here we evaluate the RNA-sequencing FusionPlex platform with a 115-gene panel including TFE3 and TFEB for tRCC diagnosis and correlate molecular findings with clinicopathological features. We reviewed 996 consecutive RCC cases from our institution over the preceding 7 years and retrieved 17 cases with histological and immunohistochemical features highly suggestive of either TFE3 (n = 16) or TFEB (n = 1). Moderate to strong labeling for TFE3 was present in 15 cases; two cases with weak TFE3 expression were melan-A or cathepsin-K positive. RNA-sequencing detected gene rearrangements in eight cases: PRCC-TFE3 (3), ASPSCR1-TFE3 (2), LUC7L3-TFE3 (1), SFPQ-TFE3 (1), and a novel SETD1B-TFE3 (1). FISH assays of 11 tumors verified six positive cases concordant with FusionPlex analysis results. Two other cases were confirmed by RT-PCR. FusionPlex was superior to FISH by providing precise breakpoints for tRCC-related genes in a single assay and allowing identification of both known and novel fusion partners, thereby facilitating clinicopathological correlations as fusion partners can influence tumor appearance, immunophenotype, and behavior. Cases with partner genes PRCC and novel partner SETD1B were associated with prominent papillary architecture while cases with partner genes ASPSCR1 and LUC7L3 were associated with a predominantly nested/alveolar pattern. The case with SFPQ-TFE3 fusion was characterized by biphasic morphology mimicking TFEB-like translocation RCC. We recommend FusionPlex analysis of RCC in patients under age 50 or when the histologic appearance suggests tRCC.

Study of KMT2B (MLL2) gene expression changes in patients with breast cancer

Aim: This study aimed to demonstrate misregulation of KMT2B gene expression in breast cancer tissue. Materials & methods: Cancerous and marginal tissue samples were collected from 43 female patients. After RNA extraction and cDNA synthesis, quantitative-PCR was used to evaluate the expression level of the KMT2B gene. REST, Sigma plot and SPSS software were used to analyze data. Results: KMT2B gene expression was significantly decreased in tumor tissue compared with marginal tissue (p = 0.02). No significant correlation was found between expression levels of KMT2B and clinical parameters of patients (p > 0.05) Conclusion: Our study demonstrated that downregulation of KMT2B is associated with breast cancer and its misregulation may play an important role in tumorigenesis.

DNA methylation and chromatin modifiers in colorectal cancer

Colorectal carcinogenesis is a multistep process involving the accumulation of genetic alterations over time that ultimately leads to disease progression and metastasis. Binding of transcription factors to gene promoter regions alone cannot explain the complex regulation pattern of gene expression during this process. It is the chromatin structure that allows for a high grade of regulatory flexibility for gene expression. Posttranslational modifications on histone proteins such as acetylation, methylation, or phosphorylation determine the accessibility of transcription factors to DNA. DNA methylation, a chemical modification of DNA that modulates chromatin structure and gene transcription acts in concert with these chromatin conformation alterations. Another epigenetic mechanism regulating gene expression is represented by small non-coding RNAs. Only very recently epigenetic alterations have been included in molecular subtype classification of colorectal cancer (CRC). In this chapter, we will provide examples of the different epigenetic players, focus on their role for epithelial-mesenchymal transition and metastatic processes and discuss their prognostic value in CRC.

Pathogenic and Therapeutic Role of H3K4 Family of Methylases and Demethylases in Cancers

Histone modifications occupy an essential position in the epigenetic landscape of the cell, and their alterations have been linked to cancers. Histone 3 lysine 4 (H3K4) methylation has emerged as a critical epigenetic cue for the regulation of gene transcription through dynamic modulation by several H3K4 methyltransferases (writers) and demethylases (erasers). Any disturbance in the delicate balance of writers and erasers can result in the mis-regulation of H3K4 methylation, which has been demonstrated in several human cancers. Therefore, H3K4 methylation has been recognized as a putative therapeutic or prognostic tool and drug trials of different inhibitors of this process have demonstrated promising results. Henceforth, more detailed knowledge of H3K4 methylation is utmost important for elucidating the complex cellular processes, which might help in improving the disease outcome. The primary focus of this review will be directed on deciphering the role of H3K4 methylation along with its writers/erasers in different cancers.