PP2A: A Promising Biomarker and Therapeutic Target in Endometrial Cancer

Detection of driver mutations and genomic signatures in endometrial cancers using artificial intelligence algorithms

Analyzed endometrial cancer (EC) genomes have allowed for the identification of molecular signatures, which enable the classification, and sometimes prognostication, of these cancers. Artificial intelligence algorithms have facilitated the partitioning of mutations into driver and passenger based on a variety of parameters, including gene function and frequency of mutation. Here, we undertook an evaluation of EC cancer genomes deposited on the Catalogue of Somatic Mutations in Cancers (COSMIC), with the goal to classify all mutations as either driver or passenger. Our analysis showed that approximately 2.5% of all mutations are driver and cause cellular transformation and immortalization. We also characterized nucleotide level mutation signatures, gross chromosomal re-arrangements, and gene expression profiles. We observed that endometrial cancers show distinct nucleotide substitution and chromosomal re-arrangement signatures compared to other cancers. We also identified high expression levels of the CLDN18 claudin gene, which is involved in growth, survival, metastasis and proliferation. We then used in silico protein structure analysis to examine the effect of certain previously uncharacterized driver mutations on protein structure. We found that certain mutations in CTNNB1 and TP53 increase protein stability, which may contribute to cellular transformation. While our analysis retrieved previously classified mutations and genomic alterations, which is to be expected, this study also identified new signatures. Additionally, we show that artificial intelligence algorithms can be effectively leveraged to accurately predict key drivers of cancer. This analysis will expand our understanding of ECs and improve the molecular toolbox for classification, diagnosis, or potential treatment of these cancers.

Molecular Characterization of Endometrial Carcinomas in Black and White Patients Reveals Disparate Drivers with Therapeutic Implications

Although the incidence of endometrial carcinoma (EC) is similar in Black and White women, racial disparities are stark, with the highest mortality rates observed among Black patients. Here, analysis of 1,882 prospectively sequenced ECs using a clinical FDA-authorized tumor-normal panel revealed a significantly higher prevalence of high-risk histologic and molecular EC subtypes in self-identified Black (n = 259) compared with White (n = 1,623) patients. Clinically actionable alterations, including high tumor mutational burden/microsatellite instability, which confer benefit from immunotherapy, were less frequent in ECs from Black than from White patients. Ultramutated POLE molecular subtype ECs associated with favorable outcomes were rare in Black patients. Results were confirmed by genetic ancestry analysis. CCNE1 gene amplification, which is associated with aggressive clinical behavior, was more prevalent in carcinosarcomas occurring in Black than in White patients. ECs from Black and White patients display important differences in their histologic types, molecular subtypes, driver genetic alterations, and therapeutic targets.

SIGNIFICANCE

Our comprehensive analysis of prospectively clinically sequenced ECs revealed significant differences in their histologic and molecular composition and in the presence of therapeutic targets in Black versus White patients. These findings emphasize the importance of incorporating diverse populations into molecular studies and clinical trials to address EC disparities. This article is featured in Selected Articles from This Issue, p. 2293.

Kinase Suppressor of RAS 1 (KSR1) Maintains the Transformed Phenotype of BRAFV600E Mutant Human Melanoma Cells

Kinase Suppressor of RAS 1 (KSR1) is a scaffolding protein for the RAS-RAF-MEK-ERK pathway, which is one of the most frequently altered pathways in human cancers. Previous results have shown that KSR1 has a critical role in mutant RAS-mediated transformation. Here, we examined the role of KSR1 in mutant BRAF transformation. We used CRISPR/Cas9 to knock out KSR1 in a BRAFV600E-transformed melanoma cell line. KSR1 loss produced a complex phenotype characterised by impaired proliferation, cell cycle defects, decreased transformation, decreased invasive migration, increased cellular senescence, and increased apoptosis. To decipher this phenotype, we used a combination of proteomic ERK substrate profiling, global protein expression profiling, and biochemical validation assays. The results suggest that KSR1 directs ERK to phosphorylate substrates that have a critical role in ensuring cell survival. The results further indicate that KSR1 loss induces the activation of p38 Mitogen-Activated Protein Kinase (MAPK) and subsequent cell cycle aberrations and senescence. In summary, KSR1 function plays a key role in oncogenic BRAF transformation.

PPP2R1A regulates migration persistence through the NHSL1-containing WAVE Shell Complex

The RAC1-WAVE-Arp2/3 signaling pathway generates branched actin networks that power lamellipodium protrusion of migrating cells. Feedback is thought to control protrusion lifetime and migration persistence, but its molecular circuitry remains elusive. Here, we identify PPP2R1A by proteomics as a protein differentially associated with the WAVE complex subunit ABI1 when RAC1 is activated and downstream generation of branched actin is blocked. PPP2R1A is found to associate at the lamellipodial edge with an alternative form of WAVE complex, the WAVE Shell Complex, that contains NHSL1 instead of the Arp2/3 activating subunit WAVE, as in the canonical WAVE Regulatory Complex. PPP2R1A is required for persistence in random and directed migration assays and for RAC1-dependent actin polymerization in cell extracts. PPP2R1A requirement is abolished by NHSL1 depletion. PPP2R1A mutations found in tumors impair WAVE Shell Complex binding and migration regulation, suggesting that the coupling of PPP2R1A to the WAVE Shell Complex is essential to its function.

Application of codon usage and context analysis in genes up- or down-regulated in neurodegeneration and cancer to combat comorbidities

Introduction

Neurodegeneration and cancer present in comorbidities with inverse effects due to the expression of genes and pathways acting in opposition. Identifying and studying the genes simultaneously up or downregulated during morbidities helps curb both ailments together.

Methods

This study examines four genes. Three of these (Amyloid Beta Precursor Protein (APP), Cyclin D1 (CCND1), and Cyclin E2 (CCNE2) are upregulated, and one protein phosphatase 2 phosphatase activator (PTPA) is simultaneously downregulated in both disorders. We investigated molecular patterns, codon usage, codon usage bias, nucleotide bias in the third codon position, preferred codons, preferred codon pairs, rare codons, and codon context.

Results

Parity analysis revealed that T is preferred over A, and G is preferred over C in the third codon position, suggesting composition plays no role in nucleotide bias in both the upregulated and downregulated gene sets and that mutational forces are stronger in upregulated gene sets than in downregulated ones. Transcript length influenced the overall %A composition and codon bias, and the codon AGG exerted the strongest influence on codon usage in both the upregulated and downregulated gene sets. Codons ending in G/C were preferred for 16 amino acids, and glutamic acid-, aspartic acid-, leucine-, valine-, and phenylalanine-initiated codon pairs were preferred in all genes. Codons CTA (Leu), GTA (Val), CAA (Gln), and CGT (Arg) were underrepresented in all examined genes.

Discussion

Using advanced gene editing tools such as CRISPR/Cas or any other gene augmentation technique, these recoded genes may be introduced into the human body to optimize gene expression levels to augment neurodegeneration and cancer therapeutic regimens simultaneously.

Prognostic stratification of endometrial cancers with high microsatellite instability or no specific molecular profile

Objective

To identify high-risk disease in clinicopathologic low-risk endometrial cancer (EC) with high microsatellite instability (MSI-H) or no specific molecular profile (NSMP) and therapeutic insensitivity in clinicopathologic high-risk MSI-H/NSMP EC.

Methods

We searched The Cancer Genome Atlas for DNA sequencing, RNA expression, and surveillance data regarding MSI-H/NSMP EC. We used a molecular classification system of E2F1 and CCNA2 expression and sequence variations in POLE, PPP2R1A, or FBXW7 (ECPPF) to prognostically stratify MSI-H/NSMP ECs. Clinical outcomes were annotated after integrating ECPPF and sequence variations in homologous recombination (HR) genes.

Results

Data were available for 239 patients with EC, which included 58 MSI-H and 89 NSMP cases. ECPPF effectively stratified MSI-H/NSMP EC into distinct molecular groups with prognostic implications: molecular low risk (MLR), with low CCNA2 and E2F1 expression, and molecular high risk (MHR), with high CCNA2 and E2F1 expression and/or PPP2R1A and/or FBXW7 variants. The 3-year disease-free survival (DFS) rate was 43.8% in the MHR group with clinicopathologic low-risk indicators and 93.9% in the MLR group (P<.001). In the MHR group, wild-type HR genes were present in 28% of cases but in 81% of documented recurrences. The 3-year DFS rate in patients with MSI-H/NSMP EC with clinicopathologic high-risk indicators was significantly higher in the MLR (94.1%) and MHR/HR variant gene (88.9%) groups than in the MHR/HR wild-type gene group (50.3%, P<.001).

Conclusion

ECPPF may resolve prognostic challenges for MSI-H/NSMP EC by identifying occult high-risk disease in EC with clinicopathologic low-risk indicators and therapeutic insensitivity in EC with clinicopathologic high-risk indicators.

Protein Phosphatase 2A: Role in T Cells and Diseases

Protein phosphatase 2A (PP2A) is a serine-threonine phosphatase that plays an important role in the regulation of cell proliferation and signal transduction. The catalytic activity of PP2A is integral in the maintenance of physiological functions which gets severely impaired in its absence. PP2A plays an essential role in the activation, differentiation, and functions of T cells. PP2A suppresses Th1 cell differentiation while promoting Th2 cell differentiation. PP2A fosters Th17 cell differentiation which contributes to the pathogenesis of systemic lupus erythematosus (SLE) by enhancing the transactivation of the Il17 gene. Genetic deletion of PP2A in Tregs disrupts Foxp3 expression due to hyperactivation of mTORC1 signaling which impairs the development and immunosuppressive functions of Tregs. PP2A is important in the induction of Th9 cells and promotes their antitumor functions. PP2A activation has shown to reduce neuroinflammation in a mouse model of experimental autoimmune encephalomyelitis (EAE) and is now used to treat multiple sclerosis (MS) clinically. In this review, we will discuss the structure and functions of PP2A in T cell differentiation and diseases and therapeutic applications of PP2A-mediated immunotherapy.

The Current Status and Future Perspectives of Chimeric Antigen Receptor-Engineered T Cell Therapy for the Management of Patients with Endometrial Cancer

Endometrial cancer (EC) is a gynecological neoplasm that is increasing in occurrence and mortality rates. Although endometrial cancer in the early stages shows a relatively favorable prognosis, there is an increase in cancer-related mortality rates in the advanced or recurrent endometrial carcinoma population and patients in the metastatic setting. This discrepancy has presented an opportunity for research and development of target therapies in this population. After obtaining promising results with hematologic cancers, chimeric antigen receptor (CAR)-T cell immunotherapy is gaining acceptance as a treatment for solid neoplasms. This treatment platform allows T cells to express tumor-specific CARs on the cell surface, which are administered to the patient to treat neoplastic cells. Given that CAR-T cell therapy has shown potential and clinical benefit compared to other T cell treatment platforms, additional research is required to overcome physiological limitations such as CAR-T cell depletion, immunosuppressive tumor microenvironment, and the lack of specific target molecules. Different approaches and development are ongoing to overcome these complications. This review examines CAR-T cell therapy's current use for endometrial carcinomas. We also discuss the significant adverse effects and limitations of this immunotherapeutic approach. Finally, we consolidate signal-seeking early-phase clinical trials and advancements that have shown promising results, leading to the approval of new immunotherapeutic agents for the disease.

From Basic Science to Clinical Practice: The Role of Cancerous Inhibitor of Protein Phosphatase 2A (CIP2A)/p90 in Cancer

Cancerous inhibitor of protein phosphatase 2A (CIP2A), initially reported as a tumor-associated antigen (known as p90), is highly expressed in most solid and hematological tumors. The interaction of CIP2A/p90, protein phosphatase 2A (PP2A), and c-Myc can hinder the function of PP2A toward c-Myc S62 induction, thus stabilizing c-Myc protein, which represents a potential role of CIP2A/p90 in tumorigeneses such as cell proliferation, invasion, and migration, as well as cancer drug resistance. The signaling pathways and regulation networks of CIP2A/p90 are complex and not yet fully understood. Many previous studies have also demonstrated that CIP2A/p90 can be used as a potential therapeutic cancer target. In addition, the autoantibody against CIP2A/p90 in sera may be used as a promising biomarker in the diagnosis of certain types of cancer. In this Review, we focus on recent advances relating to CIP2A/p90 and their implications for future research.

ECPPF (E2F1, CCNA2, POLE, PPP2R1A, FBXW7) stratification: Profiling high-risk subtypes of histomorphologically low-risk and treatment-insensitive endometrioid endometrial cancer

In endometrial cancer, occult high-risk subtypes (rooted in histomorphologically low-risk disease) with insensitivity to adjuvant therapies impede improvements in therapeutic efficacy. Therefore, we aimed to assess the ability of molecular high-risk (MHR) and low-risk (MLR) ECPPF (E2F1, CCNA2, POLE, PPP2R1A, FBXW7) stratification to profile recurrence in early, low-risk endometrioid endometrial cancer (EEC) and insensitivity to platinum-based chemotherapy or radiotherapy (or both) in high-risk EEC. Using The Cancer Genome Atlas endometrial cancer database, we identified 192 EEC cases with available DNA sequencing and RNA expression data. Molecular parameters were integrated with clinicopathologic risk factors and adverse surveillance events. MHR was defined as high (-H) CCNA2 or E2F1 log2 expression (≥2.75), PPP2R1A mutations (-mu), or FBXW7mu; MLR was defined as low (-L) CCNA2 and E2F1 log2 expression (<2.75). We assessed 164 cases, plus another 28 with POLEmu for favorable-outcomes comparisons. MHR and MLR had significantly different progression-free survival (PFS) rates (P < .001), independent of traditional risk factors (eg, TP53mu), except for stage IV disease. PFS of CCNA2-L/E2F1-L paralleled that of POLEmu. ECPPF status stratified responses to adjuvant therapy in stage III-IV EEC (P < .01) and profiled stage I, grade 1-2 cases with risk of recurrence (P < .001). MHR was associated with CTNNB1mu-linked treatment failures (P < .001). Expression of homologous recombination repair (HR) and cell cycle genes was significantly elevated in CCNA2-H/E2F1-H compared with CCNA2-L/E2F1-L (P<1.0E-10), suggesting that HR deficiencies may underlie the favorable PFS in MLR. HRmu were detected in 20.7%. No treatment failures were observed in high-grade or advanced EEC with HRmu (P = .02). Favorable PFS in clinically high-risk EEC was associated with HRmu and MLR ECPPF (P < .001). In summary, MLR ECPPF and HRmu were associated with therapeutic efficacy in EEC. MHR ECPPF was associated with low-risk, early-stage recurrences and insensitivity to adjuvant therapies.

Biased holoenzyme assembly of protein phosphatase 2A (PP2A): From cancer to small molecules

Protein phosphatase 2A (PP2A) is a family of serine threonine phosphatases responsible for regulating protein phosphorylation, thus opposing the activity of cellular kinases. PP2A is composed of a catalytic subunit (PP2A Cα/β) and scaffolding subunit (PP2A Aα/β) and various substrate-directing B regulatory subunits. PP2A biogenesis is regulated at multiple levels. For example, the sequestration of the free catalytic subunit during the process of biogenesis avoids promiscuous phosphatase activity. Posttranslational modifications of PP2A C direct PP2A heterotrimeric formation. Additionally, PP2A functions as a haploinsufficient tumor suppressor, where attenuated PP2A enzymatic activity creates a permissive environment for oncogenic transformation. Recent work studying PP2A in cancer showed that its role in tumorigenesis is more nuanced, with some holoenzymes being tumor suppressive, while others are required for oncogenic transformation. In cancer biology, PP2A function is modulated through various mechanisms including the displacement of specific B regulatory subunits by DNA tumor viral antigens, by recurrent mutations, and through loss of carboxymethyl-sensitive heterotrimeric complexes. In aggregate, these alterations bias PP2A activity away from its tumor suppressive functions and toward oncogenic ones. From a therapeutic perspective, molecular glues and disruptors present opportunities for both the selective stabilization of tumor-suppressive holoenzymes and disruption of holoenzymes that are pro-oncogenic. Collectively, these approaches represent an attractive cancer therapy for a wide range of tumor types. This review will discuss the mechanisms by which PP2A holoenzyme formation is dysregulated in cancer and the current therapies that are aimed at biasing heterotrimer formation of PP2A for the treatment of cancer.

An interactive analysis of the mouse oviductal miRNA profiles

MicroRNAs are small non-coding molecules that control several cellular functions and act as negative post-transcriptional regulators of the mRNA. While their implication in several biological functions is already known, an important role as regulators of different physiological and pathological processes in fertilization and embryo development is currently emerging. Indeed, miRNAs have been found in the oviductal fluid packaged within the extracellular vesicles, which might act as natural nanoshuttles by transporting lipids, proteins, RNA molecules and miRNAs from the oviduct to the gametes or embryos. Here, an exhaustive bibliography search was carried out, followed by the construction of a computational model based on the networks theory in an attempt to recreate and elucidate the pathways potentially activated by the oviductal miRNA. The omics data published to date were gathered to create the Oviductal MiRNome, in which the miRNA target genes and their interactions are represented by using stringApp and the Network analyzer from Cytoscape 3.7.2. Then, the hyperlinked nodes were identified to investigate the pathways in which they are involved using the gene ontology enrichment analysis. To study the phenotypical effects after the removal of key genes on the reproductive system and embryo, knockout mouse lines for every protein-coding gene were investigated by using the International Mouse Phenotyping Consortium database. The creation of the Oviductal MiRNome revealed the presence of important genes and their interactions within the network. The functional enrichment analysis revealed that the hyperlinked nodes are involved in fundamental cellular functions, both structural and regulatory/signaling, suggesting their implication in fertilization and early embryo development. This fact was as well evidenced by the effects of the gene deletion in KO mice on the reproductive system and embryo development. The present study highlights the importance of studying the miRNA profiles and their enormous potential as tools to improve the assisted reproductive techniques currently used in human and animal reproduction.

The role of serine/threonine phosphatases in human development: Evidence from congenital disorders

Reversible protein phosphorylation is a fundamental regulation mechanism in eukaryotic cell and organismal physiology, and in human health and disease. Until recently, and unlike protein kinases, mutations in serine/threonine protein phosphatases (PSP) had not been commonly associated with disorders of human development. Here, we have summarized the current knowledge on congenital diseases caused by mutations, inherited or de novo, in one of 38 human PSP genes, encoding a monomeric phosphatase or a catalytic subunit of a multimeric phosphatase. In addition, we highlight similar pathogenic mutations in genes encoding a specific regulatory subunit of a multimeric PSP. Overall, we describe 19 affected genes, and find that most pathogenic variants are loss-of-function, with just a few examples of gain-of-function alterations. Moreover, despite their widespread tissue expression, the large majority of congenital PSP disorders are characterised by brain-specific abnormalities, suggesting a generalized, major role for PSPs in brain development and function. However, even if the pathogenic mechanisms are relatively well understood for a small number of PSP disorders, this knowledge is still incomplete for most of them, and the further identification of downstream targets and effectors of the affected PSPs is eagerly awaited through studies in appropriate in vitro and in vivo disease models. Such lacking studies could elucidate the exact mechanisms through which these diseases act, and possibly open up new therapeutic avenues.

Research progress on the relationship between the TOR signaling pathway regulator, epigenetics, and tumor development

Almost all cellular activities depend on protein folding, signaling complex assembly/disassembly, and epigenetic regulation. One of the most important regulatory mechanisms responsible for controlling these cellular processes is dynamic protein phosphorylation/dephosphorylation. Alterations in phosphorylation networks have major consequences in the form of disorders, including cancer. Many signaling cascades, including the target of rapamycin (TOR) signaling, are important participants in the cell cycle, and dysregulation in their phosphorylation/dephosphorylation status has been linked to malignancies. As a TOR signaling regulator, protein phosphatase 2A (PP2A) is responsible for most of the phosphatase activities inside the cells. On the other hand, TOR signaling pathway regulator (TIPRL) is an essential PP2A inhibitory protein. Many other physiological roles have also been suggested for TIPRL, such as modulation of TOR pathways, apoptosis, and cell proliferation. It is also reported that TIPRL was increased in various carcinomas, including non-small-cell lung carcinoma (NSCLC) and hepatocellular carcinomas (HCC). Considering the function of PP2A as a tumor suppressor and also the effect of the TIPRL/PP2A axis on apoptosis and proliferation of cancer cells, this review aims to provide a complete view of the role of TIPRL in cancer development in addition to describing TIPRL/PP2A axis and its epigenetic regulation.

Cohesin in DNA damage response and double-strand break repair

Cohesin, a four-subunit ring comprising SMC1, SMC3, RAD21 and SA1/2, tethers sister chromatids by DNA replication-coupled cohesion (RC-cohesion) to guarantee correct chromosome segregation during cell proliferation. Postreplicative cohesion, also called damage-induced cohesion (DI-cohesion), is an emerging critical player in DNA damage response (DDR). In this review, we sum up recent progress on how cohesin regulates the DNA damage checkpoint activation and repair pathway choice, emphasizing postreplicative cohesin loading and DI-cohesion establishment in yeasts and mammals. DI-cohesion and RC-cohesion show distinct features in many aspects. DI-cohesion near or far from the break sites might undergo different regulations and execute different tasks in DDR and DSB repair. Furthermore, some open questions in this field and the significance of this new scenario to our understanding of genome stability maintenance and cohesinopathies are discussed.

PP2A promotes apoptosis and facilitates docetaxel sensitivity via the PP2A/p‑eIF4B/XIAP signaling pathway in prostate cancer

Serine/threonine protein phosphatase 2A (PP2A) is a protein that has a wide range of biological functions. As prostate cancer progresses from hormone-sensitive prostate cancer to castration-resistant prostate cancer (CRPC), the expression level of PP2A has been found to decrease. The present study aimed to determine the roles that PP2A may play in prostate cancer and its association with the downstream factor, X-linked inhibitor of apoptosis (XIAP). First, the mRNA and protein expression levels of PP2A in LNCaP, DU145 and PC-3 prostate cancer cell lines were measured. Next, the population of PP2A heterodimers was increased using a PP2A agonist, DT061, in the DU145 and PC-3 cell lines. PP2A expression was then knocked down in the LNCaP cell line. Western blot analysis was performed to determine the association between PP2A, phosphorylated (p)-eukaryotic initiation factor 4B (eIF4B) and XIAP. The results revealed that following the increase in PP2A expression, the DU145 and PC-3 cell lines were more sensitive to docetaxel according to Cell Counting Kit-8 assays and had an increased apoptotic rate as assessed by flow cytometry. Conversely, following the transfection of small interfering (si)PP2A into the LNCaP cell line, the sensitivity to docetaxel decreased, as well as the apoptotic rate. In addition, following treatment with the PP2A agonist, DT061, PP2A expression was found to be significantly upregulated, while p-eIF4B and XIAP protein expression levels were significantly downregulated. By contrast, following the transfection of siPP2A into the LNCaP cell line, PP2A protein expression levels were found to be downregulated, while p-eIF4B and XIAP expression levels were significantly upregulated. In conclusion, by affecting the downstream factor XIAP, PP2A may play a key role in promoting apoptosis and facilitating docetaxel sensitivity in prostate cancer cell lines.

Role of Precision Oncology in Type II Endometrial and Prostate Cancers in the African Population: Global Cancer Genomics Disparities

Precision oncology can be defined as molecular profiling of tumors to identify targetable alterations. Emerging research reports the high mortality rates associated with type II endometrial cancer in black women and with prostate cancer in men of African ancestry. The lack of adequate genetic reference information from the African genome is one of the major obstacles in exploring the benefits of precision oncology in the African context. Whilst external factors such as the geography, environment, health-care access and socio-economic status may contribute greatly towards the disparities observed in type II endometrial and prostate cancers in black populations compared to Caucasians, the contribution of African ancestry to the contribution of genetics to the etiology of these cancers cannot be ignored. Non-coding RNAs (ncRNAs) continue to emerge as important regulators of gene expression and the key molecular pathways involved in tumorigenesis. Particular attention is focused on activated/repressed genes and associated pathways, while the redundant pathways (pathways that have the same outcome or activate the same downstream effectors) are often ignored. However, comprehensive evidence to understand the relationship between type II endometrial cancer, prostate cancer and African ancestry remains poorly understood. The sub-Saharan African (SSA) region has both the highest incidence and mortality of both type II endometrial and prostate cancers. Understanding how the entire transcriptomic landscape of these two reproductive cancers is regulated by ncRNAs in an African cohort may help elucidate the relationship between race and pathological disparities of these two diseases. This review focuses on global disparities in medicine, PCa and ECa. The role of precision oncology in PCa and ECa in the African population will also be discussed.

Molecular analysis of endometrial serous carcinoma reveals distinct clinicopathologic and genomic subgroups

OBJECTIVES

Endometrial serous carcinoma (EMSC) is an aggressive variant of uterine cancer with limited therapeutic options. We sought to define distinct clinicopathologic and genomic EMSC subgroups.

METHODS

We retrospectively analyzed 2159 EMSC and 2346 endometrioid-type endometrial carcinomas (EEC) tissue specimens that had undergone comprehensive genomic profiling (CGP) via the FoundationOne CDx assay during routine clinical care. High tumor mutational burden (TMB) was defined as ≥10mut/Mb using the FDA-approved CDx cutoff for pembrolizumab. Microsatellite instability (MSI) was determined on 95 loci. Evidence of homologous recombination deficiency (HRD) was determined via genomic loss of heterozygosity (gLOH), a validated HRD detection method for predicting PARP inhibitor effectiveness in ovarian carcinoma. High gLOH was defined as ≥16%.

RESULTS

A genomic analysis of 2159 EMSCs revealed a predominance of TP53 mutations, microsatellite stability, low tumor mutational burden (TMB), and recurrent alterations of PIK3CA, PPP2R1A, ERBB2, CCNE1, FBXW7 and MYC. Evidence of HRD via high gLOH was identified in 22% of EMSCs. BRCA1 and BRCA2 alterations, as well as unique SET (solid, pseudo-endometrioid, and transitional cell-like) variant morphology, were enriched in HRD-EMSC. There was an increased frequency of CCNE1 amplification, a lower prevalence of PIK3CA and PPP2R1A alterations, and no differences in HRD, MSI or TMB biomarker frequencies in patients of predicted African ancestry. EMSC exhibited distinct gene mutation frequencies and MSI, TMB and gLOH biomarker signatures compared to a cohort 2346 EEC.

CONCLUSIONS

Molecularly defined subgroups provide a framework to test the susceptibility of EMSC to targeted therapies in specific genetic settings (e.g. HRD, PIK3CA, PPP2R1A, ERBB2, MYC, CCNE1).

Delineating the intra-patient heterogeneity of molecular alterations in treatment-naïve colorectal cancer with peritoneal carcinomatosis

In a non-negligible number of patients with metastatic colorectal cancer (mCRC), the peritoneum is the predominant site of dissemination. Cure can be achieved by cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC), but this procedure is associated with long-term morbidity and high relapse rates. Thus, there is a pressing need for improved therapeutic strategies and complementary biomarkers. The present study explored the molecular heterogeneity in mCRC with peritoneal carcinomatosis (PC), and the potential clinical implications thereof. Multi-region immunohistochemical profiling and deep targeted DNA-sequencing was performed on chemotherapy-naïve tumours from seven patients with synchronous colorectal PC who underwent CRS and HIPEC. In total, 88 samples (5-19 per patient) were analysed, representing primary tumour, lymph node metastases, tumour deposits, PC and liver metastases. Expression of special AT-rich sequence-binding protein 2 (SATB2), a marker of colorectal lineage, was lacking in the majority of cases, and a conspicuous intra-patient heterogeneity was denoted for expression of the proposed prognostic and predictive biomarker RNA-binding motif protein 3 (RBM3). Loss of mismatch repair proteins MLH1 and PSM2, observed in one case, was concordant with microsatellite instability and the highest tumour mutational burden. When present in a patient, mutations in key CRC driver genes, i.e., KRAS, APC and TP53, were homogenously distributed across all samples, while less common mutations were more heterogenous. On the same note, copy number variations showed intra-patient as well inter-patient heterogeneity. In two out of seven cases, hierarchical clustering revealed that samples from the PC and lymph node metastases were more similar to each other than to the primary tumour. In summary, these findings should encourage additional studies addressing the potential distinctiveness of mCRC with PC, which might pave the way for improved personalized treatment of these patients.

TRIM29 regulates the SETBP1/SET/PP2A axis via transcription factor VEZF1 to promote progression of ovarian cancer

Ovarian cancer (OC) is a common gynecological malignant tumor that seriously endangers the health of women worldwide. Tripartite motif containing 29 (TRIM29) is a TRIM family member that is frequently overexpressed in OC. However, the specific role of TRIM29 in OC remains obscure. To investigate the underlying molecular mechanism, a global proteomics analysis identified SET binding protein 1 (SETBP1) as a crucial target of TRIM29. Subsequently, the SETBP1/SET/Protein phosphatase 2 (PP2A) axis was confirmed to be required for the recovery of cancer stem cell (CSC)-like phenotype suppressed by TRIM29 knockdown. Mechanistically, TRIM29 facilitated SETBP1 transcriptional activation via the VEZF1 transcription factor. More importantly, TRIM29 promoted VEZF1 mRNA translation by recruiting RNA binding protein BICC1 to its 3'UTR. The clinical significance was established by the association of TRIM29 and SETBP1 expression with clinicopathological features in OC samples. The SETBP1/SET/PP2A axis driven by TRIM29 via transcription factor VEZF1 is at least one of the primary mechanisms underlying TRIM29 maintenance of the CSC-like characteristics in OC.

Protein phosphatase 2A in the healthy and failing heart: New insights and therapeutic opportunities

Protein phosphatases have emerged as critical regulators of phosphoprotein homeostasis in settings of health and disease. Protein phosphatase 2A (PP2A) encompasses a large subfamily of enzymes that remove phosphate groups from serine/threonine residues within phosphoproteins. The heterogeneity in PP2A structure, which arises from the grouping of different catalytic, scaffolding and regulatory subunit isoforms, creates distinct populations of catalytically active enzymes (i.e. holoenzymes) that localise to different parts of the cell. This structural complexity, combined with other regulatory mechanisms, such as interaction of PP2A heterotrimers with accessory proteins and post-translational modification of the catalytic and/or regulatory subunits, enables PP2A holoenzymes to target phosphoprotein substrates in a highly specific manner. In this review, we summarise the roles of PP2A in cardiac physiology and disease. PP2A modulates numerous processes that are vital for heart function including calcium handling, contractility, β-adrenergic signalling, metabolism and transcription. Dysregulation of PP2A has been observed in human cardiac disease settings, including heart failure and atrial fibrillation. Efforts are underway, particularly in the cancer field, to develop therapeutics targeting PP2A activity. The development of small molecule activators of PP2A (SMAPs) and other compounds that selectively target specific PP2A holoenzymes (e.g. PP2A/B56α and PP2A/B56ε) will improve understanding of the function of different PP2A species in the heart, and may lead to the development of therapeutics for normalising aberrant protein phosphorylation in settings of cardiac remodelling and dysfunction.

Meta-GWAS of PCSK9 levels detects two novel loci at APOB and TM6SF2

Background

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key player in lipid metabolism, as it degrades low-density lipoprotein (LDL) receptors from hepatic cell membranes. So far, only variants of the PCSK9 gene locus were found to be associated with PCSK9 levels. Here we aimed to identify novel genetic loci that regulate PCSK9 levels and how they relate to other lipid traits. Additionally, we investigated to what extend the causal effect of PCSK9 on coronary artery disease (CAD) is mediated by low-density lipoprotein–cholesterol (LDL–C).

Methods and Results

We performed a genome-wide association study meta-analysis of PCSK9 levels in up to 12 721 samples of European ancestry. The estimated heritability was 10.3%, which increased to 12.6% using only samples from patients without statin treatment. We successfully replicated the known PCSK9 hit consisting of three independent signals. Interestingly, in a study of 300 African Americans, we confirmed the locus with a different PCSK9 variant. Beyond PCSK9, our meta-analysis detected three novel loci with genome-wide significance. Co-localization analysis with cis-eQTLs and lipid traits revealed biologically plausible candidate genes at two of them: APOB and TM6SF2. In a bivariate Mendelian Randomization analysis, we detected a strong effect of PCSK9 on LDL-C, but not vice versa. LDL-C mediated 63% of the total causal effect of PCSK9 on CAD.

Conclusion

Our study identified novel genetic loci with plausible candidate genes affecting PCSK9 levels. Ethnic heterogeneity was observed at the PCSK9 locus itself. Although the causal effect of PCSK9 on CAD is mainly mediated by LDL-C, an independent direct effect also occurs.

circRNA circ_POLA2 increases microRNA-31 methylation to promote endometrial cancer cell proliferation

Circular RNA (circRNA) circ_POLA2 is an oncogene in lung and cervical cancers. However, the role of circ_POLA2 in other types of cancer is unknown. The present study investigated the role of circ_POLA2 in endometrial cancer (EC). The mRNA expression levels of circ_POLA2 and microRNA (miR)-31 in EC and paired adjacent normal tissues were analyzed using reverse transcription-quantitative (RT-qPCR). Overexpression of circ_POLA2 was achieved in the EC cell lines, and its effects on miR-31 mRNA expression level and methylation were evaluated using RT-qPCR and methylation-specific PCR (MSP), respectively. Cell proliferation was assessed using a Cell Counting Kit-8 assay. The results indicated that circ_POLA2 was highly expressed in EC tissue and inversely correlated with miR-31 mRNA expression level. MSP analysis showed that circ_POLA2 overexpression increased miR-31 methylation and RT-qPCR analysis showed that circ_POLA2 overexpression decreased miR-31 mRNA expression level. Furthermore, circ_POLA2 overexpression also increased EC cell proliferation, while miR-31 overexpression decreased cell proliferation. Finally, circ_POLA2 overexpression reduced the effects of miR-31 overexpression. In conclusion, circ_POLA2 may increase miR-31 methylation of miR-31 in EC cells to promote cancer cell proliferation.

Cancer stem cell phosphatases

Cancer stem cells (CSCs) are involved in the initiation and progression of human malignancies by enabling cancer tissue self-renewal capacity and constituting the therapy-resistant population of tumor cells. However, despite the exhausting characterization of CSC genetics, epigenetics, and kinase signaling, eradication of CSCs remains an unattainable goal in most human malignancies. While phosphatases contribute equally with kinases to cellular phosphoregulation, our understanding of phosphatases in CSCs lags severely behind our knowledge about other CSC signaling mechanisms. Many cancer-relevant phosphatases have recently become druggable, indicating that further understanding of the CSC phosphatases might provide novel therapeutic opportunities. This review summarizes the current knowledge about fundamental, but yet poorly understood involvement of phosphatases in the regulation of major CSC signaling pathways. We also review the functional roles of phosphatases in CSC self-renewal, cancer progression, and therapy resistance; focusing particularly on hematological cancers and glioblastoma. We further discuss the small molecule targeting of CSC phosphatases and their therapeutic potential in cancer combination therapies.

Protein Phosphatase 2A (PP2A) mutations in brain function, development, and neurologic disease

By removing Ser/Thr-specific phosphorylations in a multitude of protein substrates in diverse tissues, Protein Phosphatase type 2A (PP2A) enzymes play essential regulatory roles in cellular signalling and physiology, including in brain function and development. Here, we review current knowledge on PP2A gene mutations causally involved in neurodevelopmental disorders and intellectual disability, focusing on PPP2CA, PPP2R1A and PPP2R5D. We provide insights into the impact of these mutations on PP2A structure, substrate specificity and potential function in neurobiology and brain development.

PP2A and E3 ubiquitin ligase deficiencies: Seminal biological drivers in endometrial cancer

OBJECTIVE

PI3K-AKT pathway mutations initiate a kinase cascade that characterizes endometrial cancer (EC). As kinases seldom cause oncogenic transformation without dysregulation of antagonistic phosphatases, pivotal interactions governing this pathway were explored and correlated with clinical outcomes.

METHODS

After exclusion of patients with POLE mutations from The Cancer Genome Atlas EC cohort with endometrioid or serous EC, the study population was 209 patients with DNA sequencing, quantitative gene-specific RNA expression, copy number variation (CNV), and surveillance data available. Extracted data were annotated and integrated.

RESULTS

A PIK3CA, PTEN, or PIK3R1 mutant (-mu) was present in 83% of patients; 57% harbored more than 1 mutation without adversely impacting progression-free survival (PFS) (P = .10). PIK3CA CNV of at least 1.1 (CNV high [-H]) was detected in 26% and linked to TP53-mu and CIP2A expression (P < .001) but was not associated with PFS (P = .24). PIK3CA expression was significantly different between those with CIP2A-H and CIP2A low (-L) expression (the endogenous inhibitor of protein phosphatase 2A [PP2A]), when stratified by PIK3CA mutational status or by PIK3CA CNV-H and CNV-L (all P < .01). CIP2A-H or PPP2R1A-mu mitigates PP2A kinase dephosphorylation, and FBXW7-mu nullifies E3 ubiquitin ligase (E3UL) oncoprotein degradation. CIP2A-H and PPP2R1A-mu (PP2A impairment) and FBXW7-mu (E3UL impairment) were associated with compromised PFS (P < .001) and were prognostically discriminatory for PIK3CA-mu and PIK3CA CNV-H tumors (P < .001). Among documented recurrences, 84% were associated with impaired PP2A (75%) and/or E3UL (20%).

CONCLUSION

PP2A and E3UL deficiencies are seminal biological drivers in EC independent of PIK3CA-mu, PTEN-mu, and PIK3R1-mu and PIK3CA CNV.

In search for biomarkers and potential drug targets for uterine serous endometrial cancer

Objective

Serous endometrial cancer (USC) is a challenging malignancy associated with metastasis, recurrence and poor outcome. To identify clinically relevant prognostic biomarkers, we focused on a panel of proteins selected after a comprehensive literature review, for tumour profiling of a homogeneous cohort of USC patients.

Methods

Protein levels and localization were assessed by immunohistochemistry analysis in 36 hysterectomy samples. Tissue sections were stained with the following antibodies: Aurora A, phospho (T288) Aurora A, BRCA1, CHK1, CIP2A, Cyclin B1, Cyclin E, E2F-1, phospho (S364) E2F-1, FBXW7, FOXM1, phospho (S9) GSK3Beta, PLK1, phospho (T210) PLK1, PPP2R1B, p73, RAD51. Each marker was evaluated as a continuously-scaled variable for association with disease progression and death, using Cox proportional hazards models. The sample consisted of 36 patients with USC, half with stage III or IV disease.

Results

Results showed that higher CHK1 (Checkpoint kinase 1) expression was associated with a decreased risk of progression and death, after adjusting for stage. Interestingly, analysis of a TCGA data set of 109 USC patients corroborates our results showing a favourable prognostic role of CHEK1 after adjusting for stage. Higher FBXW7 (F-box and WD repeat domain containing 7) expression and higher cytoplasmic expression of PPP2R1B (Protein Phosphatase 2 A, Scaffold Subunit Abeta) were each associated with a decreased risk of progression, after adjusting for stage.

Conclusions

In conclusion, results from the present study identify new clinically relevant biomarkers and potential drug targets for uterine serous endometrial cancer.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-021-03566-x.

Immunotherapy and Its Development for Gynecological (Ovarian, Endometrial and Cervical) Tumors: From Immune Checkpoint Inhibitors to Chimeric Antigen Receptor (CAR)-T Cell Therapy

Gynecological tumors are malignancies with both high morbidity and mortality. To date, only a few chemotherapeutic agents have shown efficacy against these cancer types (only ovarian cancer responds to several agents, especially platinum-based combinations). Within this context, the discovery of immune checkpoint inhibitors has led to numerous clinical studies being carried out that have also demonstrated their activity in these cancer types. More recently, following the development of chimeric antigen receptor (CAR)-T cell therapy in hematological malignancies, this strategy was also tested in solid tumors, including gynecological cancers. In this article, we focus on the molecular basis of gynecological tumors that makes them potential candidates for immunotherapy. We also provide an overview of the main immunotherapy studies divided by tumor type and report on CAR technology and the studies currently underway in the area of gynecological malignancies.

The role of Popeye domain-containing protein 1 (POPDC1) in the progression of the malignant phenotype

The Popeye domain-containing protein 1 (POPDC1), a tight junction-associated transmembrane protein with a unique binding site for cAMP, has been shown to act as a tumour suppressor in cancer cells. Through interaction with many downstream effectors and signalling pathways, POPDC1 promotes cell adhesion and inhibits uncontrolled cell proliferation, epithelial-to-mesenchymal transition and metastasis. However, POPDC1 expression is down-regulated in many types of cancer, thereby reducing its tumour-suppressive actions. This review discusses the role of POPDC1 in the progression of the malignant phenotype and highlights the broad range of benefits POPDC1 stabilisation may achieve therapeutically. Cancer stem cells (CSCs) are a key hallmark of malignancies and commonly promote treatment resistance. This article provides a comprehensive overview of CSC signalling mechanisms, many of which have been shown to be regulated by POPDC1 in other cell types, thus suggesting an additional therapeutic benefit for POPDC1-stabilising anti-cancer drugs.

CIP2A regulates MYC translation (via its 5'UTR) in colorectal cancer

BACKGROUND

Deregulated expression of MYC is a driver of colorectal carcinogenesis, suggesting that decreasing MYC expression may have significant therapeutic value. CIP2A is an oncogenic factor that regulates MYC expression. CIP2A is overexpressed in colorectal cancer (CRC), and its expression levels are an independent marker for long-term outcome of CRC. Previous studies suggested that CIP2A controls MYC protein expression on a post-transcriptional level.

METHODS

To determine the mechanism by which CIP2A regulates MYC in CRC, we dissected MYC translation and stability dependent on CIP2A in CRC cell lines.

RESULTS

Knockdown of CIP2A reduced MYC protein levels without influencing MYC stability in CRC cell lines. Interfering with proteasomal degradation of MYC by usage of FBXW7-deficient cells or treatment with the proteasome inhibitor MG132 did not rescue the effect of CIP2A depletion on MYC protein levels. Whereas CIP2A knockdown had marginal influence on global protein synthesis, we could demonstrate that, by using different reporter constructs and cells expressing MYC mRNA with or without flanking UTR, CIP2A regulates MYC translation. This interaction is mainly conducted by the MYC 5'UTR.

CONCLUSIONS

Thus, instead of targeting MYC protein stability as reported for other tissue types before, CIP2A specifically regulates MYC mRNA translation in CRC but has only slight effects on global mRNA translation. In conclusion, we propose as novel mechanism that CIP2A regulates MYC on a translational level rather than affecting MYC protein stability in CRC.

Synthesis and Biological Evaluation of the Southern Hemisphere of Spirastrellolide A and Analogues

The synthesis and biological evaluation of truncated spirastrellolide A analogues comprised of the southern hemisphere against protein phosphatase 2A are described. A convergent synthesis was designed featuring two gold-catalyzed cyclization reactions, specifically, a dehydrative cyclization of monoallylic diols for the synthesis of the tetrahydropyran (A-ring) and a regioselective spiroketalization for the efficient generation of the [6,6]-spiroketal (B, C-ring system). The synthesis of the southern hemisphere of spirastrellolide A was achieved involving the longest linear sequence of 19 steps. A total of eight spirastrellolide A analogues were synthesized, and preliminary PP2A enzyme assay inhibition studies were performed for the first time on analogues of the southern hemisphere. Several analogues showed inhibition, which is a positive indication and perhaps suggests that the unsaturated spiroketal fragment might be crucial to induce PP2A inhibition.

Histomolecular features of high-grade endometrial cancers

High-grade endometrial cancers (ECs) are an aggressive subset of ECs accounting for 70-80% of EC-related deaths. Currently, staging surgery, together with chemotherapy or radiotherapy, is the primary treatment strategy for these cancers. The widespread use of next-generation sequencing has led to a refined understanding of EC's genomics with important information for diagnosis and therapy for individual patients (precision medicine). However, advances in the genomics assessment of high-grade tumors have been slower due to their lower incidence than low-grade EC. This article will briefly introduce the current state of knowledge of the genomics of G3 endometrioid EC, serous uterine cancer, clear cell uterine carcinoma and uterine carcinosarcoma and discuss its implications for diagnosis and targeted therapy.

Genomics and splicing events of type II endometrial cancers in the black population: racial disparity, socioeconomic and geographical differences

Endometrial cancer, also known as uterine cancer, is the most common gynaecological malignancy with burgeoning incidence and mortality rates globally. Racial disparity, socioeconomic and geographical differences are important determinants of endometrial cancer incidence and mortality. Endometrial cancer is mainly categorised as type I and type II. Although less prevalent, type II is the most aggressive form of the disease and typically diagnosed at a late stage, contributing to higher mortality. Black women are at higher risk of developing aggressive, type II disease. Type I tumours are related to higher levels of circulating estrogen with lower-grade tumours that have a good prognosis and frequently related to PTEN mutations. In comparison, type II tumours are estrogen-independent, typically have poor prognosis and associated with the p53, HER2, PPP2R1A, FBXW7 and PIK3R1 mutations. The risk of developing type II malignancy is higher in women with Lynch syndrome as a result of mutations in the MMR gene family. Genetic modifications contribute to aberrant alternative splicing events that are related to tumour development, progression and resistance to therapy. Alternative splicing events are rapidly emerging as potential biomarkers and therapeutic targets. Type II endometrial cancer lacks targeted therapy and biomarkers for novel therapeutic strategies. Recent advances have illustrated a number of molecular targets that are currently explored for the treatment of advanced, late-stage endometrial cancer. The aim of this review is to outline 1) the epidemiology of type II endometrial cancer in black women, 2) discuss the correlated risk factors that contribute to the development of type II endometrial cancer and 3) the associated molecular mechanisms and genetic factors underlying the disease, and 4) aberrant splicing events and biomarkers with therapeutic potential as novel drug targets.

The Curcumin Analogue, EF-24, Triggers p38 MAPK-Mediated Apoptotic Cell Death via Inducing PP2A-Modulated ERK Deactivation in Human Acute Myeloid Leukemia Cells

Curcumin (CUR) has a range of therapeutic benefits against cancers, but its poor solubility and low bioavailability limit its clinical use. Demethoxycurcumin (DMC) and diphenyl difluoroketone (EF-24) are natural and synthetic curcumin analogues, respectively, with better solubilities and higher anti-carcinogenic activities in various solid tumors than CUR. However, the efficacy of these analogues against non-solid tumors, particularly in acute myeloid leukemia (AML), has not been fully investigated. Herein, we observed that both DMC and EF-24 significantly decrease the proportion of viable AML cells including HL-60, U937, and MV4-11, harboring different NRAS and Fms-like tyrosine kinase 3 (FLT3) statuses, and that EF-24 has a lower half maximal inhibitory concentration (IC₅₀) than DMC. We found that EF-24 treatment induces several features of apoptosis, including an increase in the sub-G₁ population, phosphatidylserine (PS) externalization, and significant activation of extrinsic proapoptotic signaling such as caspase-8 and -3 activation. Mechanistically, p38 mitogen-activated protein kinase (MAPK) activation is critical for EF-24-triggered apoptosis via activating protein phosphatase 2A (PP2A) to attenuate extracellular-regulated protein kinase (ERK) activities in HL-60 AML cells. In the clinic, patients with AML expressing high level of PP2A have the most favorable prognoses compared to various solid tumors. Taken together, our results indicate that EF-24 is a potential therapeutic agent for treating AML, especially for cancer types that lose the function of the PP2A tumor suppressor.

Pharmacokinetics and Tolerability of the Novel Non-immunosuppressive Fingolimod Derivative, OSU-2S, in Dogs and Comparisons with Data in Mice and Rats

In this study, we characterized the pharmacokinetics of OSU-2S, a fingolimod-derived, non-immunosuppressive phosphatase activator, in mice, rats, and dogs, as well as tolerability and food effects in dogs. Across all species tested, plasma protein binding for OSU-2S was > 99.5%, and metabolic stability and hepatic intrinsic clearance were in the moderate range. OSU-2S did not significantly modulate CYP enzyme activity up until 50 μM, and Caco-2 data suggested low permeability with active efflux at 2 μM. Apparent oral bioavailability in mice was 16% and 69% at 10 and 50 mg/kg, respectively. In rats, bioavailability was 24%, 35%, and 28% at 10, 30, and 100 mg/kg, respectively, while brain/plasma ratio was 36 at 6-h post-dose at 30 mg/kg. In dogs, OSU-2S was well tolerated with oral capsule bioavailability of 27.5%. Plasma OSU-2S exposures increased proportionally over a 2.5-20 mg/kg dose range. After 4 weeks of 3 times weekly, oral administration (20 mg/kg), plasma AUC_last (26.1 μM*h), and C_max (0.899 μM) were nearly 2-fold greater than those after 1 week of dosing, and no food effects were observed. The elimination half-life (29.7 h), clearance (22.9 mL/min/kg), and plasma concentrations of repeated oral doses support a 3-times weekly dosing schedule in dogs. No significant CBC, serum biochemical, or histopathological changes were observed. OSU-2S has favorable oral PK properties similar to fingolimod in rodents and dogs and is well tolerated in healthy animals. This work supports establishing trials of OSU-2S efficacy in dogs with spontaneous tumors to guide its clinical development as a cancer therapeutic for human patients.

MnTE-2-PyP Suppresses Prostate Cancer Cell Growth via H2O2 Production

Prostate cancer patients are often treated with radiotherapy. MnTE-2-PyP, a superoxide dismutase (SOD) mimic, is a known radioprotector of normal tissues. Our recent work demonstrated that MnTE-2-PyP also inhibits prostate cancer progression with radiotherapy; however, the mechanisms remain unclear. In this study, we identified that MnTE-2-PyP-induced intracellular H₂O₂ levels are critical in inhibiting the growth of PC3 and LNCaP cells, but the increased H₂O₂ levels affected the two cancer cells differently. In PC3 cells, many proteins were thiol oxidized with MnTE-2-PyP treatment, including Ser/Thr protein phosphatase 1 beta catalytic subunit (PP1CB). This resulted in reduced PP1CB activity; however, overall cell cycle progression was not altered, so this is not the main mechanism of PC3 cell growth inhibition. High H₂O₂ levels by MnTE-2-PyP treatment induced nuclear fragmentation, which could be synergistically enhanced with radiotherapy. In LNCaP cells, thiol oxidation by MnTE-2-PyP treatment was not observed previously and, similarly to PC3 cells, there was no effect of MnTE-2-PyP treatment on cell cycle progression. However, in LNCaP cells, MnTE-2-PyP caused an increase in low RNA population and sub-G₁ population of cells, which indicates that MnTE-2-PyP treatment may cause cellular quiescence or direct cancer cell death. The protein oxidative modifications and mitotic catastrophes caused by MnTE-2-PyP may be the major contributors to cell growth inhibition in PC3 cells, while in LNCaP cells, tumor cell quiescence or cell death appears to be major factors in MnTE-2-PyP-induced growth inhibition.

A New World of Biomarkers and Therapeutics for Female Reproductive System and Breast Cancers: Circular RNAs

As one of the most recently (re)discovered types of non-coding RNAs (ncRNA), circular RNAs (circRNAs) differentiate from other ncRNAs by a specific biogenesis, high stability, and distinct functions. The biogenesis of circRNAs can be categorized into three mechanisms that permit the back-splicing reaction: exon-skipping, pairing of neighboring introns, and dimerization of RNA-binding proteins. Regarding their stability, circRNAs have no free ends, specific to linear RNA molecules, prompting a longer half-life and resistance to exonuclease-mediated activity by RNase R, bypassing the common RNA turnover process. Regarding their functions, circular transcripts can be categorized into four broad roles: miRNA sponging, protein binding, regulation of transcription, and coding for proteins and peptides. Female reproductive system (including mainly ovarian, corpus, and cervix uteri cancers) and breast cancers are the primary causes of death in women worldwide, accounting for over 1,212,772 deaths in 2018. We consider that a better understanding of the molecular pathophysiology through the study of coding and non-coding RNA regulators could improve the diagnosis and therapeutics of these cancers. Developments in the field of circRNA in regard to breast or gynecological cancers are recent, with most circRNA-related discoveries having been made in the last 2 years. Therefore, in this review we summarize the newly detected roles of circRNAs in female reproductive system (cervical cancer, ovarian cancer, and endometrial cancer) and breast cancers. We argue that circRNAs can become essential elements of the diagnostic and therapeutic tools for female reproductive system cancers in the future.

Challenges and Opportunities for Therapeutic Targeting of Calmodulin Kinase II in Heart

Heart failure remains a major health burden around the world. Despite great progress in delineation of molecular mechanisms underlying development of disease, standard therapy has not advanced at the same pace. The multifunctional signaling molecule Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) has received considerable attention over recent years for its central role in maladaptive remodeling and arrhythmias in the setting of chronic disease. However, these basic science discoveries have yet to translate into new therapies for human patients. This review addresses both the promise and barriers to developing translational therapies that target CaMKII signaling to abrogate pathologic remodeling in the setting of chronic disease. Efforts in small molecule design are discussed, as well as alternative targeting approaches that exploit novel avenues for compound delivery and/or genetic approaches to affect cardiac CaMKII signaling. These alternative strategies provide hope for overcoming some of the challenges that have limited the development of new therapies.