Histone methylation is a critical regulator of the abnormal expression of POU5F1 and RASSF1A in testis cancer cell lines

Epigenetic Factors and ncRNAs in Testicular Cancer

Testicular cancer is the most prevalent tumor among males aged 15 to 35, resulting in a significant number of newly diagnosed cases and fatalities annually. Non-coding RNAs (ncRNAs) have emerged as key regulators in various cellular processes and pathologies, including testicular cancer. Their involvement in gene regulation, coding, decoding, and overall gene expression control suggests their potential as targets for alternative treatment approaches for this type of cancer. Furthermore, epigenetic modifications, such as histone modifications, DNA methylation, and the regulation by microRNA (miRNA), have been implicated in testicular tumor progression and treatment response. Epigenetics may also offer critical insights for prognostic evaluation and targeted therapies in patients with testicular germ cell tumors (TGCT). This comprehensive review aims to present the latest discoveries regarding the involvement of some proteins and ncRNAs, mainly miRNAs and lncRNA, in the epigenetic aspect of testicular cancer, emphasizing their relevance in pathogenesis and their potential, given the fact that their specific expression holds promise for prognostic evaluation and targeted therapies.

H3 histone methylation landscape in male urogenital cancers: from molecular mechanisms to epigenetic biomarkers and therapeutic targets

During the last decades, male urogenital cancers (including prostate, renal, bladder and testicular cancers) have become one of the most frequently encountered malignancies affecting all ages. While their great variety has promoted the development of various diagnosis, treatment and monitoring strategies, some aspects such as the common involvement of epigenetic mechanisms are still not elucidated. Epigenetic processes have come into the spotlight in the past years as important players in the initiation and progression of tumors, leading to a plethora of studies highlighting their potential as biomarkers for diagnosis, staging, prognosis, and even as therapeutic targets. Thus, fostering research on the various epigenetic mechanisms and their roles in cancer remains a priority for the scientific community. This review focuses on one of the main epigenetic mechanisms, namely, the methylation of the histone H3 at various sites and its involvement in male urogenital cancers. This histone modification presents a great interest due to its modulatory effect on gene expression, leading either to activation (e.g., H3K4me3, H3K36me3) or repression (e.g., H3K27me3, H3K9me3). In the last few years, growing evidence has demonstrated the aberrant expression of enzymes that methylate/demethylate histone H3 in cancer and inflammatory diseases, that might contribute to the initiation and progression of such disorders. We highlight how these particular epigenetic modifications are emerging as potential diagnostic and prognostic biomarkers or targets for the treatment of urogenital cancers.

Epigenetic Regulation of Driver Genes in Testicular Tumorigenesis

In testicular germ cell tumor type II (TGCT), a seminoma subtype expresses an induced pluripotent stem cell (iPSC) panel with four upregulated genes, OCT4/POU5F1, SOX17, KLF4, and MYC, and embryonal carcinoma (EC) has four upregulated genes, OCT4/POU5F1, SOX2, LIN28, and NANOG. The EC panel can reprogram cells into iPSC, and both iPSC and EC can differentiate into teratoma. This review summarizes the literature on epigenetic regulation of the genes. Epigenetic mechanisms, such as methylations of cytosines on the DNA string and methylations and acetylations of histone 3 lysines, regulate expression of these driver genes between the TGCT subtypes. In TGCT, the driver genes contribute to well-known clinical characteristics and the driver genes are also important for aggressive subtypes of many other malignancies. In conclusion, epigenetic regulation of the driver genes are important for TGCT and for oncology in general.

Non-additive effect of the DNA methylation inhibitor, 5-Aza-dC, and glass as a culture surface on osteogenic differentiation

The clinical need for bone regenerative solutions is expanding with increasing life expectancy and escalating incidence of accidents. Several strategies are being investigated to enhance the osteogenic differentiation of stem cells. We previously reported two different approaches for this purpose, in monolayer and three-dimensional cell culture. The first approach was based on pretreating cells with 5-Aza-dC, a DNA methylation inhibitor, before the applying the differentiation media. The second approach was based on culturing cells on a glass surface during differentiation. In this study, we investigated the potential effect of combining both methods. Our results suggested that both approaches were associated with decreasing global DNA methylation levels. Cells cultured as a monolayer on glass surface showed enhancement in alkaline phosphatase activity at day 10, while 5-Aza-dC pretreatment enhanced the activity at day 5, irrespective of the culture surface. In three-dimensional pellet culture, 5-Aza-dC pretreatment enhanced osteogenesis through Runx-2 and TGF-β1 upregulation while the glass surface induced Osterix. Furthermore, pellets cultured on glass showed upregulation of a group of miRNAs, including pro-osteogenesis miR- 20a and miR -148b and anti-osteogenesis miR -125b, miR -31, miR -138, and miR -133a. Interestingly, 5-Aza-dC was not associated with a change of miRNAs in cells cultured on tissue culture plastic but reverted the upregulated miRNAs on the glass to the basal level. This study confirms the two approaches for enhancing osteogenic differentiation and contradicts their combination.

Combining Hypermethylated RASSF1A Detection Using ddPCR with miR-371a-3p Testing: An Improved Panel of Liquid Biopsy Biomarkers for Testicular Germ Cell Tumor Patients

The classical serum tumor markers used routinely in the management of testicular germ cell tumor (TGCT) patients-alpha fetoprotein (AFP) and human chorionic gonadotropin (HCG)-show important limitations. miR-371a-3p is the most recent promising biomarker for TGCTs, but it is not sufficiently informative for detection of teratoma, which is therapeutically relevant. We aimed to test the feasibility of hypermethylated RASSF1A (RASSF1AM) detected in circulating cell-free DNA as a non-invasive diagnostic marker of testicular germ cell tumors, combined with miR-371a-3p. A total of 109 serum samples of patients and 29 sera of healthy young adult males were included, along with representative cell lines and tumor tissue samples. We describe a novel droplet digital polymerase chain reaction (ddPCR) method for quantitatively assessing RASSF1AM in liquid biopsies. Both miR-371a-3p (sensitivity = 85.7%) and RASSF1AM (sensitivity = 86.7%) outperformed the combination of AFP and HCG (sensitivity = 65.5%) for TGCT diagnosis. RASSF1AM detected 88% of teratomas. In this representative cohort, 14 cases were negative for miR-371a-3p, all of which were detected by RASSF1AM, resulting in a combined sensitivity of 100%. We have described a highly sensitive and specific panel of biomarkers for TGCT patients, to be validated in the context of patient follow-up and detection of minimal residual disease.

Targeting Germ Cell Tumors with the Newly Synthesized Flavanone-Derived Compound MLo1302 Efficiently Reduces Tumor Cell Viability and Induces Apoptosis and Cell Cycle Arrest

Less toxic treatment strategies for testicular germ cell tumor (TGCT) patients are needed, as overtreatment is a concern due to the long-term side effects of platin-based chemotherapy. Although clinical benefit from classical hypomethylating agents has to date been limited, TGCTs show an abnormal DNA methylome indicating the potential of treating TGCTs with hypomethylating drugs. We tested, for the first time in TGCT cell lines, a new synthetic flavonoid compound (MLo1302) from the 3-nitroflavanone family of DNA methyltransferase (DNMT) inhibitors. We show that MLo1302 reduces cell viability (including of cisplatin resistant cell line NCCIT-R), with IC₅₀s (inhibitory concentration 50) within the nanomolar range for NCCIT and NTERA-2 cells, and proved its cytotoxic effect. Exposure to MLo1302 reduced DNMT protein expression, similar to decitabine, and showed a partial effect in cell differentiation, reducing protein expression of pluripotency markers. RT² profiler expression array indicated several dysregulated targets, related to activation of apoptosis, differentiation, and cell cycle arrest. We validated these data by showing increased apoptosis, increased protein expression of cleaved caspase 8 and activated caspase 2, and reduced proliferation (BrdU assay), with increase in CDKN1A and decrease in MIB-1 expression. Therefore, synthetic drugs designed to target DNA methylation in cells may uncover effective treatments for TGCT patients.

Epigenetic alterations as therapeutic targets in Testicular Germ Cell Tumours : current and future application of 'epidrugs'

Testicular germ cell tumours (TGCTs) are heterogeneous neoplasms mostly affecting young-adult men. Despite high survival rates, some patients with disseminated disease acquire cisplatin resistance, entailing the need for less toxic therapies. Epigenetic alterations constitute an important feature of TGCTs, which are also implicated in resistance mechanism(s). These alterations might be used as potential targets to design epigenetic drugs. To date, several compounds have been explored and evaluated regarding therapeutic efficacy, making use of pre-clinical studies with in vitro and in vivo models, and some have already been explored in clinical trials. This review summarizes the several epigenetic mechanisms at play in these neoplasms, the current challenges in the field of TGCTs and critically reviews available data on 'epidrugs' in those tumours.

Non-Coding microRNAs as Novel Potential Tumor Markers in Testicular Cancer

Testicular cancer is an important disease with increasing incidence and a high burden of morbidity and mortality in young men worldwide. Histological examination of the testicular tissue after orchiectomy plays an important role alongside patient history, imaging, clinical presentation and laboratory parameters. Surgical procedures and chemotherapeutic treatment provide a high chance of cure in early stages, though some patients in advanced stages belonging to a poor risk group experience cancer-related death. Though conventional serum-based tumor markers, including α-fetoprotein (AFP), the β-subunit of human chorionic gonadotropin (β-hCG), and lactate dehydrogenase (LDH), are useful as prognostic and diagnostic biomarkers, unfortunately, these tumor markers only have a sensitivity of about 60%, and in pure seminoma even lower with about 20%. Therefore, the development of new tumor markers is an important and intensively ongoing issue. The analysis of epigenetic modification and non-coding RNA microRNAs (miRNAs) are carrying most promising potential as tumor markers in future. miRNAs are small RNAs secreted by testicular tumor cells and circulate and be measurable in body fluids. In recent years, miRNAs of the miR-371-373 cluster in particular have been identified as potentially superior tumor markers in testicular cancer patients. Studies showed that miR-371a-3p and miR-302/367 expression significantly differ between testicular tumors and healthy testicular tissue. Several studies including high prospective multi-center trials clearly demonstrated that these miRNAs significantly exceed the sensitivity and specificity of conventional tumor markers and may help to facilitate the diagnosis, follow-up, and early detection of recurrences in testicular cancer patients. In addition, other miRNAs such as miR-223-3p, miR-449, miR-383, miR-514a-3p, miR-199a-3p, and miR-214 will be discussed in this review. However, further studies are needed to identify the value of these novel markers in additional clinical scenarios, including the monitoring in active surveillance or after adjuvant chemotherapy, but also to show the limitations of these tumor markers. The aim of this review is to give an overview on the current knowledge regarding the relevance of non-coding miRNAs as biomarkers in testicular cancer.

Exploring the molecular aspects associated with testicular germ cell tumors: a review

Testicular germ cell tumors (TGCTs) represent the most common solid tumors affecting young men. They constitute a distinct entity because of their embryonic origin and their unique biological behavior. Recent preclinical data regarding biological signaling machinery as well as genetic and epigenetic mechanisms associated with molecular patterns of tumors have contribute to explain the pathogenesis and the differentiation of TGCTs and to understand the mechanisms responsible for the development of resistance to treatment. In this review, we discuss the main genetic and epigenetic events associated with TGCTs development in order to better define their role in the pathogenesis of these tumors and in cisplatin-acquired resistance.

Current Concepts of Epigenetics in Testicular Cancer

Testicular germ cell tumors (GCTs) are characterized into seminomas (SGCTs) and non-seminomatous testicular germ cell tumors (NSGCTs). Serum tumor markers (STMs) play an important role in testicular cancer as they provide useful information for diagnosis, staging, and detection of recurrence. Nonetheless, additional tumor markers for early diagnosis and therapeutic options are required to enhance specificity of serological diagnosis of testes cancers. Epigenetics is defined as inherited changes in gene expression that are not encoded in the DNA structure. Epigenetic changes include DNA methylation, histone modifications, and microRNA (miRNA) regulation. It is through the study of epigenetics that diagnostic methods for early detection and novel therapeutic strategies may be established for testicular cancer. We performed a comprehensive review of the English medical literature in PubMed by combining search terms including DNA methylation, histone modifications, microRNA (miRNA) regulation, epigenetics, and testicular cancer. DNA methylation is the most extensively studied epigenetic modification. It consists of the addition of a methyl group to nucleotide bases. It has been reported that SGCT contain reduced levels of DNA methylation compared to NSGCT. MiRNAs are small non-coding RNAs that regulate posttranscriptional gene expression. It has been suggested that miRNAs may play a role in the pathogenesis of GCT. Specific expression patterns have been displayed by various miRNAs in patients with GCT. Histones are proteins intertwined with coiled, double-stranded genomic DNA that form a structure known as a nucleosome. The most widely studied histone modifications include acetylation, methylation, and phosphorylation. Methylation of histone proteins has been found in all types of NSGCT. Epigenetics may offer an additional and effective tool in establishing a diagnosis of GCT of the testes, including prognostic information and perhaps enabling targeted treatment in patients with testicular GCT.

The epigenetics of testicular germ cell tumors: looking for novel disease biomarkers

Testicular germ cell tumors (TGCT) are a group of heterogeneous, biologically diverse and clinically challenging neoplasms. Despite the relatively low incidence and mortality rates, a subgroup of patients with disseminated disease relapse after conventional therapy and have a dismal prognosis. Moreover, TGCT afflict mostly young men and have therapeutic peculiarities, with some patients showing resistance to cisplatin-based treatments and others being troubled by irreversible side effects, such as infertility. Most TGCT share a common tumorigenic pathway and are cytogenetically similar, making room for Epigenetics to explain its heterogeneity at pathological and clinical level. In this review, we summarize the foremost epigenetic alterations among TGCT focusing on their clinical potential as diagnostic, prognostic and predictive biomarkers.

The histone demethylase KDM1A is essential for the maintenance and differentiation of spermatogonial stem cells and progenitors

Little is known of the fundamental processes governed by epigenetic mechanisms in the supplier cells of spermatogenesis, the spermatogonial stem cells (SSCs). The histone H3 lysine demethylase KDM1A is expressed in spermatogonia. We hypothesized that KDM1A serves in transcriptional regulation of SSCs and fertility. Using a conditional deletion of Kdm1a [conditional knockout (cKO)] in mouse spermatogonia, we determined that Kdm1a is essential for spermatogenesis as adult cKO males completely lack germ cells. Analysis of postnatal testis development revealed that undifferentiated and differentiating spermatogonial populations form in Kdm1a-cKO animals, yet the majority fail to enter meiosis. Loss of germ cells in the cKO was rapid with none remaining by postnatal day (PND) 21. To gain insight into the mechanistic implications of Kdm1a ablation, we isolated PND 6 spermatogonia enriched for SSCs and analyzed their transcriptome by RNA sequencing. Loss of Kdm1a was associated with altered transcription of 1206 genes. Importantly, differentially expressed genes between control and Kdm1a-cKO animals included those that are essential for SSC and progenitor maintenance and spermatogonial differentiation. The complete loss of fertility and failure to establish spermatogenesis indicate that Kdm1a is a master controller of gene transcription in spermatogonia and is required for SSC and progenitor maintenance and differentiation.

Genistein downregulates onco-miR-1260b and upregulates sFRP1 and Smad4 via demethylation and histone modification in prostate cancer cells

Background:

Recently several microRNAs (miRNAs) have been found to be regulated by genistein in cancer cells. In this study, we focused on the gene regulatory effect of genistein on microRNA and its target genes in prostate cancer (PC).

Methods:

Initially, we investigated the effect of genistein on prostate cancer cells and identified that the expression of miRNA-1260b was decreased by genistein. We performed functional analyses and investigated the relationship between miRNA-1260b expression and prostate cancer patient outcomes. Two target genes (sFRP1 and Smad4) of miR-1260b were identified based on computer algorithm and 3′UTR luciferase assay was carried out to determine direct miRNA regulation of the genes.

Results:

Genistein promoted apoptosis while inhibiting prostate cancer cell proliferation, invasion and TCF reporter activity in PC cells. MiR-1260b was highly expressed in prostate cancer tissues and significantly downregulated by genistein in PC cells. After knocking down miR-1260b, cell proliferation, invasion, migration and TCF reporter activity were decreased in PC cells. Western analysis and 3′UTR luciferase assay showed that the two target genes (sFRP1 and Smad4) were directly regulated by miR-1260b. The expression of sFRP1 and Smad4 was significantly decreased in prostate cancer tissues. Genistein also increased expression of these two genes via DNA demethylation and histone modifications.

Conclusions:

Our data suggest that genistein exerts its anti-tumour effect via downregulation of miR-1260b that targeted sRRP1 and Smad4 genes in prostate cancer cells. The expression of sFRP1 and Smad4 was also modulated by genistein via DNA methylation or histone modifications in PC cell lines.

Epigenetic: a molecular link between testicular cancer and environmental exposures

In the last decades, studies in rodents have highlighted links between in utero and/or neonatal exposures to molecules that alter endocrine functions and the development of genital tract abnormalities, such as cryptorchidism, hypospadias, and impaired spermatogenesis. Most of these molecules, called endocrine disrupters exert estrogenic and/or antiandrogenic activities. These data led to the hypothesis of the testicular dysgenesis syndrome which postulates that these disorders are one clinical entity and are linked by epidemiological and pathophysiological relations. Furthermore, infertility has been stated as a risk factor for testicular cancer (TC). The incidence of TC has been increasing over the past decade. Most of testicular germ cell cancers develop through a pre-invasive carcinoma in situ from fetal germ cells (primordial germ cell or gonocyte). During their development, fetal germ cells undergo epigenetic modifications. Interestingly, several lines of evidence have shown that gene regulation through epigenetic mechanisms (DNA and histone modifications) plays an important role in normal development as well as in various diseases, including TC. Here we will review chromatin modifications which can affect testicular physiology leading to the development of TC; and highlight potential molecular pathways involved in these alterations in the context of environmental exposures.

Epigenetic biomarkers in urological tumors: A systematic review

Prostate, bladder, kidney and testis cancers, the most common genitourinary (GU) neoplasms, are generally clinically silent at their earliest stages when curative treatment is most likely successful. However, there are no consensual guidelines for GU cancer screening and available methods are characterized by suboptimal sensitivity and specificity. Moreover, standard clinical and pathological parameters meet with important limitations in the assessment of prognosis in an individual basis. Herein, we focus on the development of epigenetic-based GU cancer biomarkers, which have emerged from exploratory studies in recent years and that hold the promise to revolutionize the clinical management of GU cancer patients.

Dissecting the molecular pathways of (testicular) germ cell tumour pathogenesis; from initiation to treatment-resistance

Human type II germ cell tumours (GCTs) originate from an embryonic germ cell, either as a primordial germ cell or gonocyte. This start determines the biological as well as clinical characteristics of this type of cancer, amongst others their totipotency as well as their overall (exceptional) sensitivity to DNA damaging agents. The histology of the precursor lesion, either carcinoma in situ or gonadoblastoma, depends on the level of testicularization (i.e. testis formation) of the gonad. The impact of either intrinsic (genetic) - and environmental factors involved in the pathogenesis is demonstrated by disorders of sex development as well as testicular dysgenesis syndrome as risk factors, including cryptorchidism, hypospadias and disturbed fertility as parameters. This knowledge allows identification of individuals at risk for development of this type of cancer, being a population of interest for screening. Factors known to regulate pluripotency during embryogenesis are proven to be of diagnostic value for type II GCTs, including OCT3/4, even applicable for non-invasive screening. In addition, presence of stem cell factor, also known as KITLG, allows distinction between delayed matured germ cells and the earliest stages of malignant transformation. This is of special interest because of the identified association between development of type II GCTs of the testis and a limited number of single nucleotide polymorphisms, including some likely related to KITL. Transition from the precursor lesion to an invasive cancer is associated with gain of the short arm of chromosome 12, in which multiple genes might be involved, including KRAS2 and possibly NANOG (pseudogenes). While most precursor lesions will progress to an invasive cancer, only a limited number of cancers will develop treatment resistance. Putative explanatory mechanisms are identified, including presence of microsatellite instability, BRAF mutations, apoptosis suppression and p21 sub-cellular localization. It remains to be investigated how these different pathways integrate to each other and how informative they are at the patient-individual level. Further understanding will allow development of more targeted treatment, which will benefit quality of life of these young cancer patients.

Novel retrotransposed imprinted locus identified at human 6p25

Differentially methylated regions (DMRs) are stable epigenetic features within or in proximity to imprinted genes. We used this feature to identify candidate human imprinted loci by quantitative DNA methylation analysis. We discovered a unique DMR at the 5′-end of FAM50B at 6p25.2. We determined that sense transcripts originating from the FAM50B locus are expressed from the paternal allele in all human tissues investigated except for ovary, in which expression is biallelic. Furthermore, an antisense transcript, FAM50B-AS, was identified to be monoallelically expressed from the paternal allele in a variety of tissues. Comparative phylogenetic analysis showed that FAM50B orthologs are absent in chicken and platypus, but are present and biallelically expressed in opossum and mouse. These findings indicate that FAM50B originated in Therians after divergence from Prototherians via retrotransposition of a gene on the X chromosome. Moreover, our data are consistent with acquisition of imprinting during Eutherian evolution after divergence of Glires from the Euarchonta mammals. FAM50B expression is deregulated in testicular germ cell tumors, and loss of imprinting occurs frequently in testicular seminomas, suggesting an important role for FAM50B in spermatogenesis and tumorigenesis. These results also underscore the importance of accounting for parental origin in understanding the mechanism of 6p25-related diseases.