A comprehensive analysis of somatic alterations in Chinese ovarian cancer patients

APOBEC3A drives metastasis of high-grade serous ovarian cancer by altering epithelial-to-mesenchymal transition

High-grade serous ovarian cancer (HGSOC) is the most prevalent and aggressive histological subtype of ovarian cancer, and often presents with metastatic disease. The drivers of metastasis in HGSOC remain enigmatic. APOBEC3A (A3A), an enzyme that generates mutations across various cancers, has been proposed as a mediator of tumor heterogeneity and disease progression. However, the role of A3A in HGSOC has not been explored. Through analysis of genome sequencing from primary HGSOC, we observed an association between high levels of APOBEC3 mutagenesis and poor overall survival. We experimentally addressed this correlation by modeling A3A activity in HGSOC cell lines and mouse models which resulted in increased metastatic behavior of HGSOC cells in culture and distant metastatic spread in vivo . A3A activity in both primary and cultured HGSOC cells yielded consistent alterations in expression of epithelial-mesenchymal-transition (EMT) genes resulting in hybrid EMT and mesenchymal signatures, and providing a mechanism for their increased metastatic potential. Our findings define the prevalence of A3A mutagenesis in HGSOC and implicate A3A as a driver of HGSOC metastasis via EMT, underscoring its clinical relevance as a potential prognostic biomarker. Our study lays the groundwork for the development of targeted therapies aimed at mitigating the deleterious impact of A3A-driven EMT in HGSOC.

Putative Dual Roles of Bone Morphogenetic Protein 8B (BMP8B) in Disease Progression of Gastric Cancer

Background/Aim

Increased expression of bone morphogenetic protein 8B (BMP8B) in bone marrow and primary tumors of patients with gastric cancer (GC) is associated with disease progression and poor prognosis. However, a reduced expression has also been seen in GCs due to histone acetylation. This study aimed to evaluate BMP8B transcript levels in a large GC cohort and its impact on cellular functions.

Materials and Methods

BMP8B transcripts were determined in 319 gastric tumors and compared with 182 adjacent normal tissues using real time PCR, with a further analysis conducted in the TCGA database. Kaplan-Meier plotter analysis was performed to evaluate the correlation between BMP8B and prognosis of the disease. BMP8B knockdown model was employed to determine the effect of BMP8B on the function of GC cells (HGC27).

Results

BMP8B mRNA levels were significantly up-regulated in the GC tissues compared with adjacent normal tissues in both TCGA database and our own database from Beijing Cancer Hospital, and high BMP8B expression was associated with poor prognosis. BMP8B is most likely to be involved in the differentiation of GC. Poorly differentiated GC samples presented a significantly reduced BMP8B expression in relation to well-differentiated and moderately differentiated GC. BMP8B knockdown inhibited proliferation of GC cells, while promoted invasion and migration of cancer cells.

Conclusion

BMP8B was reduced in GCs, whereas higher BMP8B expression was associated with poor prognosis. BMP8B knockdown inhibited proliferation of GC cells, and promoted invasion and migration. Our results suggest that BMP8B plays dual roles in GC.

An integrated machine learning-based model for joint diagnosis of ovarian cancer with multiple test indicators

OBJECTIVE

To construct a machine learning diagnostic model integrating feature dimensionality reduction techniques and artificial neural network classifiers to develop the value of clinical routine blood indexes for the auxiliary diagnosis of ovarian cancer.

METHODS

Patients with ovarian cancer clearly diagnosed in our hospital were collected as a case group (n = 185), and three groups of patients with other malignant otolaryngology tumors (n = 138), patients with benign otolaryngology diseases (n = 339) and those with normal physical examination (n = 92) were used as an overall control group. In this paper, a fully automated segmentation network for magnetic resonance images of ovarian cancer is proposed to improve the reproducibility of tumor segmentation results while effectively reducing the burden on radiologists. A pre-trained Res Net50 is used to the three edge output modules are fused to obtain the final segmentation results. The segmentation results of the proposed network architecture are compared with the segmentation results of the U-net based network architecture and the effect of different loss functions and region of interest sizes on the segmentation performance of the proposed network is analyzed.

RESULTS

The average Dice similarity coefficient, average sensitivity, average specificity (specificity) and average hausdorff distance of the proposed network segmentation results reached 83.62%, 89.11%, 96.37% and 8.50, respectively, which were better than the U-net based segmentation method. For ROIs containing tumor tissue, the smaller the size, the better the segmentation effect. Several loss functions do not differ much. The area under the ROC curve of the machine learning diagnostic model reached 0.948, with a sensitivity of 91.9% and a specificity of 86.9%, and its diagnostic efficacy was significantly better than that of the traditional way of detecting CA125 alone. The model was able to accurately diagnose ovarian cancer of different disease stages and showed certain discriminative ability for ovarian cancer in all three control subgroups.

CONCLUSION

Using machine learning to integrate multiple conventional test indicators can effectively improve the diagnostic efficacy of ovarian cancer, which provides a new idea for the intelligent auxiliary diagnosis of ovarian cancer.

Application of precision medicine based on next-generation sequencing and immunohistochemistry in ovarian cancer: a real-world experience

OBJECTIVE

To evaluate the landscape of gene alterations and immunohistochemistry (IHC) profiles of patients with ovarian cancer for targeted therapy and investigate the real-world experience of applying precision medicine.

METHODS

Patients diagnosed with ovarian cancer between January 2015 and May 2021 at Severance Hospital and who underwent tumor next-generation sequencing (NGS) were reviewed. Data on germline mutation, IHC markers for mismatch repair deficiency (MMRd), programmed death ligand 1 (PD-L1) expression, and human epidermal growth factor receptor 2 (HER2) expression were acquired. The use of matched therapy and its clinical outcomes were evaluated.

RESULTS

Of the 512 patients who underwent tumor NGS, 403 underwent panel-based germline testing. In patients who underwent both tests, tumor NGS identified 39 patients (9.7%) with BRCA mutations and 16 patients (4.0%) with other homologous recombination repair (HRR)-associated gene mutations, which were not found in germline testing. The most common single nucleotide variants were TP53 (82.2%), ARID1A (10.4%), PIK3CA (9.7%), and KRAS (8.4%). Copy number aberrations were found in 122 patients. MMRd was found in 3.2% of patients, high PD-L1 expression in 10.1%, and HER2 overexpression in 6.5%. Subsequently, 75 patients (14.6%) received a poly (ADP-ribose) polymerase inhibitor based on BRCA mutation and 11 patients (2.1%) based on other HRR-associated gene mutations. Six patients (1.2%) with MMRd underwent immunotherapy. Twenty-eight patients (5.5%) received other matched therapies targeting HER2, fibroblast growth factor receptor, folate receptor alpha, RAS, and PIK3CA.

CONCLUSION

A comprehensive review of germline mutation, IHC, and tumor NGS helped identify candidates for precision therapy in patients with ovarian cancer, a proportion of whom received matched therapy.

The Prognostic Significance of Tumor-Infiltrating Lymphocytes, PD-L1, BRCA Mutation Status and Tumor Mutational Burden in Early-Stage High-Grade Serous Ovarian Carcinoma-A Study by the Spanish Group for Ovarian Cancer Research (GEICO)

Early stages are under-represented in studies on the molecular and immune features of high-grade serous ovarian carcinoma (HGSOC), and specific studies focused on early-stage HGSOC are required for a better prognostic stratification and to personalize chemotherapy. The aim of this study was to determine the prognostic significance of CD8+ and CD4+ tumor-infiltrating lymphocytes (TILs), tumoral cell PD-L1 expression, BRCA mutational status and tumor mutation burden (TMB) in early-stage HGSOC. A retrospective study was performed on stage I and II HGSOC from the Molecular Reclassification of Early Stages of Ovarian Cancer (RECLAMO) cohort from the Spanish Group of Ovarian Cancer Research (GEICO). Centralized histological typing was performed based on morphological and immunohistochemical features. Intraepithelial (i) and stromal (s) CD8+ and CD4+ T cells and PD-L1 were evaluated on tissue microarrays by immunohistochemistry. BRCA1 and BRCA2 mutation status and TMB were analyzed in tumor DNA using next-generation sequencing. The study included 124 tumors. High iCD8+ (>20 TILs/core), low/intermediate CD4+ (<20 TILs/core) and high CD8+/CD4+ ratio (>35/core) were associated with favorable outcomes. Tumor cell PD-L1 expression (TPS ≥ 1) was present in only 8% of tumors. In total, 11 (16%) and 6 (9%) out of 69 HGSOC tested carried pathogenic or likely pathogenic BRCA1 or BRCA2 mutations, respectively. Median TMB of 40 tumors analyzed was 5.04 mutations/Mb and only 6 tumors had 10 or more mutations/Mb. BRCA status and TMB were not associated with TILs or prognosis. When compared with studies on advanced HGSOC, our results suggested that prognostic variables differed according to stage and that more studies focused on early stages of HGSOC are needed to better stratify these tumors.

Improved detection of homologous recombination deficiency in Chinese patients with ovarian cancer: a novel non-exonic single-nucleotide polymorphism-based next-generation sequencing panel

As homologous recombination deficiency (HRD) is a biomarker to predict the efficiency of PARP inhibitor treatment, this study developed a non-exonic single-nucleotide polymorphism (SNP)-based targeted next-generation sequencing panel and comprehensively examined it both on standard and clinical ovarian cancer tissues. The HRD scores calculated by the panel and whole-genome sequencing were consistent, with the analysis by sequenza being the most reliable. The results on clinical samples revealed that the panel performed better in HRD analysis compared with the SNP microarray. There are several distinctions between this newly developed kit and reported HRD detection panels. First, the panel covers only 52 592 SNPs, which makes it capable of detecting genomic instability. Secondly, all the SNPs are non-exonic; as a result, the panel can be used cooperatively with any exon panel. Thirdly, all the SNPs selected have a high minor allele frequency in Chinese people, making it a better choice for HRD detection in Chinese patients. In summary, this panel shows promise as a clinical application to guide PARP inhibitors or platinum drugs used in the treatment of ovarian and other cancers.

LRP2 and DOCK8 Are Potential Antigens for mRNA Vaccine Development in Immunologically 'Cold' KIRC Tumours

The administration of mRNA-based tumour vaccines is considered a promising strategy in tumour immunotherapy, although its application against kidney renal clear cell carcinoma (KIRC) is still at its infancy stage. The purpose of this study was to identify potential antigens and to further select suitable patients for vaccination. Gene expression data and clinical information were retrieved from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases. GEPIA2 was used to evaluate the prognostic value of selected antigens. The relationship of antigens presenting cell infiltration with antigen expression was evaluated by TIMER, and immune subtypes were determined using unsupervised cluster analysis. Tumour antigens LRP2 and DOCK8, which are associated with prognosis and tumour-infiltrating antigen-presenting cells, were identified in KIRC. A total of six immune subtypes were identified, and patients with immune subtype 1-4 (IS1-4) tumours had an immune 'cold' phenotype, a higher tumour mutation burden, and poor survival. Moreover, these immune subtypes showed significant differences in the expression of immune checkpoint and immunogenic cell death modulators. Finally, the immune landscape of KIRC revealed the immune-related cell components in individual patients. This study suggests that LRP2 and DOCK8 are potential KIRC antigens in the development of mRNA vaccines, and patients with immune subtypes IS1-4 are suitable for vaccination.

Characteristics of homologous recombination repair pathway genes mutation in ovarian cancers

Background

Few studies have investigated the characteristics of non-BRCA homologous recombination repair (HRR) pathway somatic mutations, and the impact of these mutations on efficacy of treatment in ovarian cancer patients is not clear. Therefore, we conducted this study to analyze the frequency and spectrum of somatic mutations in HRR pathway genes in patients with ovarian cancer and to examine the relationships between somatic mutations in HRR pathway genes and their effects on the efficacy of platinum-based chemotherapy.

Methods

We performed targeted sequencing of 688 genes related to the occurrence, development, treatment, and prognosis of solid tumors. Somatic mutations were identified by paired analysis of tumor tissue and germline DNA in blood cells.

Results

A total of 38 patients with ovarian cancer were included in the study, and 35 (92.1%) patients were diagnosed with high-grade serous carcinoma. All patients exhibited somatic mutations in the tumor tissue samples. The commonly mutated genes were TP53 (73.7%), BRCA2 (55.3%), NF1 (52.6%), BRCA1 (47.4%), and CDH1 (47.4%). Overall, 71.1% of the patients exhibited mutation in at least one HRR pathway gene. The most frequently altered HRR genes were BRCA2 (55.3%), followed by BRCA1 (47.4%), ATM (44.7%), BARD1 (42.1%), and CHEK1 (36.8%). The median progression-free survival (PFS) in patients with HRR pathway mutation was 36.0 months compared with 13.6 months in patients with no HRR pathway mutation (hazard ratio [HR], 0.25; 95% confidence interval [CI], 0.08-0.77; p = 0.016). Patients harboring BRCA1/2 and/or CDK12 mutations displayed a longer PFS (median, 36.0 months) compared with patients with no BRCA1/2 or CDK12 mutation (median, 13.6 months; HR, 0.21; 95% CI, 0.07-0.61; p = 0.004). In multivariate analysis Cox proportional hazards models, after adjustment for tumor stage at diagnosis and histology of initial diagnosis, patients with HRR pathway mutation had a longer PFS than patients with HRR wild-type genes (p = 0.006).

Conclusions

HRR pathway somatic mutations are common in Chinese patients with ovarian cancer. HRR pathway somatic mutations were associated with improved sensitivity to platinum-based chemotherapy. Large-scale prospective studies are needed to verify our findings.

RAD54B mutations enhance the sensitivity of ovarian cancer cells to poly(ADP-ribose) polymerase (PARP) inhibitors

Synthetic lethal targeting of homologous recombination (HR)–deficient ovarian cancers (OvCas) with poly(ADP-ribose) polymerase inhibitors (PARPis) has attracted considerable attention. Olaparib was the first PARPi approved by the Food and Drug Administration, offering significant clinical benefits in BRCA1/2-deficient OvCas. However, only approximately 20% of OvCa patients harbor BRCA1/2 mutations. Given the shared roles that BRCA1/2 have with other HR regulators, alterations in HR genes may also contribute to “BRCAness profiles” in OvCas. RAD54B has been considered a key player in HR repair, although its roles and therapeutic potential in cancers need further investigation. Here, we identified 22 frequently mutated HR genes by whole-exome sequencing of OvCa tissues from 82 patients. To our surprise, 7.3% of patients were found to harbor mutations of RAD54B, the third-highest mutated gene among patients. We determined that RAD54B-mutated tumor tissues harbored more DNA double-strand breaks than normal tissues. Additionally, we found that RAD54B knockdown inhibited HR repair, enhanced sensitivities of OvCa cells with increased DNA double-strand breaks to olaparib, and induced apoptosis. Enhanced inhibitory effects of olaparib on the growth of ES2 xenograft tumors were further demonstrated by RAD54B knockdown. Finally, we show that restoration with wildtype RAD54B rather than RAD54B^N593S and RAD54B^H219Y, identified in patients, abolished the effects of RAD54B knockdown, indicating these RAD54B mutants probably malfunctioned in HR repair. Our investigations may offer insight into the contributions of RAD54B mutations to synthetic lethality with olaparib treatment in OvCas, enrich the gene list for “HR deficiency scoring,” and expand the applications of PARPis.

Analysis of Novel Variants Associated with Three Human Ovarian Cancer Cell Lines

Background:

Identification of mutations is of great significance in cancer research, as it can contribute to development of therapeutic strategies and prevention of cancer formation. Ovarian cancer is one of the leading cancer-related causes of death in Taiwan. Accumulation of genetic mutations can lead to cancer.

Objective:

We utilized whole-exome sequencing to explore cancer-associated missense variants in three human ovarian cancer cell lines derived from Taiwanese patients.

Methods:

We use (i) cell line whole-exome sequencing data, (ii) 188 patients’ whole-exome sequencing data, and (iii) use of in vitro experiments to verify predicted variant results. We establish an effective analysis workflow for discovery of novel ovarian cancer variants, comprising three steps: (i) use of public databases and in-house hospital data to select novel variants (ii) investigation of protein structural stability caused by genetic mutations, and (iii) use of in vitro experiments to verify predictions.

Results:

Our study enumerated 296 novel variants by imposing specific criteria and using sophisticated bioinformatics tools for further analysis. Eleven and 54 missense novel variants associated with cancerous and non-cancerous genes, respectively, were identified. We show that 13 missense mutations affect the stability of protein 3D structure, while 11 disease-causing novel variants were confirmed by PCR sequencing. Among these, ten variants were predicted to be pathogenic, while the pathogenicity of one was uncertain.

Conclusion:

We confirm that novel variant genes play a crucial role in ovarian cancer patients, with 11 novel variants that may promote progression and development of ovarian cancer.

The role of mediator subunit 12 in tumorigenesis and cancer therapeutics (Review)

Mediator complex subunit 12 (MED12) is a subunit of Mediator, a large multi-subunit protein complex that acts an important regulator of transcription. Specifically, MED12 is an integral part of the kinase module of Mediator along with MED13, CyclinC (CycC) and CDK8. Structural studies have indicated that MED12 makes a direct connection to CycC through a specific interface and thereby functions to create a link between MED13 and CycC-CDK8. Disruption of the MED12-CycC interface often leads to dysregulated CDK8 kinase activity, which has important physiological implications. For example, a number of studies have indicated that mutations within MED12 can lead to the formation of benign or malignant tumors, either as a result of MED12-CycC disruption or through distinct independent mechanisms. Furthermore, recent studies have indicated that the N-terminal portion of MED12 forms a direct connection to CDK8. Mutations within MED12 do not appear to disrupt the physical connection to CDK8, but rather abrogate CDK8 kinase activity. Thus, mutations in MED12 can cause disruption of CDK8 kinase activity through two separate mechanisms. The aim of the present review article was to discuss the MED12 mutational landscape in a variety of benign and malignant tumors, as well as the mechanistic basis behind tumorigenesis. Furthermore, the link between MED12 and drug resistance has also been discussed, as well as potential cancer therapeutics related to MED12-altered tumors.

Somatic Mutational Profile of High-Grade Serous Ovarian Carcinoma and Triple-Negative Breast Carcinoma in Young and Elderly Patients: Similarities and Divergences

Background: Triple-negative breast cancer (TNBC) and High-Grade Serous Ovarian Cancer (HGSOC) are aggressive malignancies that share similarities; however, different ages of onset may reflect distinct tumor behaviors. Thus, our aim was to compare somatic mutations in potential driver genes in 109 TNBC and 81 HGSOC from young (Y ≤ 40 years) and elderly (E ≥ 75 years) patients. Methods: Open access mutational data (WGS or WES) were collected for TNBC and HGSOC patients. Potential driver genes were those that were present in the Cancer Gene Census—CGC, the Candidate Cancer Gene Database—CCGD, or OncoKB and those that were considered pathogenic in variant effect prediction tools. Results: Mutational signature 3 (homologous repair defects) was the only gene that was represented in all four subgroups. The median number of mutated CGCs per sample was similar in HGSOC (Y:3 vs. E:4), but it was higher in elderly TNBC than it was in young TNBC (Y:3 vs. E:6). At least 90% of the samples from TNBC and HGSOC from Y and E patients presented at least one known affected TSG. Besides TP53, which was mutated in 67–83% of the samples, the affected TSG in TP53 wild-type samples were NF1 (yHGSOC and yTNBC), PHF6 (eHGSOC and yTNBC), PTEN, PIK3R1 and ZHFX3 (yTNBC), KMT2C, ARID1B, TBX3, and ATM (eTNBC). A few samples only presented one affected oncogene (but no TSG): KRAS and TSHR in eHGSOC and RAC1 and PREX2 (a regulator of RAC1) in yTNBC. At least ⅔ of the tumors presented mutated oncogenes associated with tumor suppressor genes; the Ras and/or PIK3CA signaling pathways were altered in 15% HGSOC and 20–35% TNBC (Y vs. E); DNA repair genes were mutated in 19–33% of the HGSOC tumors but were more frequently mutated in E-TNBC (56%). However, in HGSOC, 9.5% and 3.3% of the young and elderly patients, respectively, did not present any tumors with an affected CGC nor did 4.65% and none of the young and elderly TNBC patients. Conclusion: Most HGSOC and TNBC from young and elderly patients present an affected TSG, mainly TP53, as well as mutational signature 3; however, a few tumors only present an affected oncogene or no affected cancer-causing genes.

Screening of differentially expressed miRNAs during osteogenic/odontogenic differentiation of human dental pulp stem cells exposed to mechanical stress

MicroRNAs (miRNAs) have been demonstrated as crucial transcriptional regulators in proliferation, differentiation, and tumorigenesis. The comprehensive miRNA profiles of osteogenic/odontogenic differentiation of human dental pulp stem cells (hDPSCs) under the condition of mechanical stress remains largely unknown. In this study, we aimed to discover the miRNA expression profiles of hDPSCs exposed to mechanical stress under the osteogenic/odontogenic process. We found that mechanical stress (0.09 MPa and 0.18 MPa, respectively, 30 min/day) significantly promoted the proliferation of hDPSCs since the fifth day. The expressions of DSPP, DMP1, and RUNX2 were significantly increased on day 7 in the presence of 0.09 MPa and 0.18 MPa mechanical stress. On day 14, the expression levels of DSPP, DMP1, and RUNX2 were decreased in the presence of mechanical stress. Among 2578 expressed miRNAs, 5 miRNAs were upregulated and 3 miRNAs were downregulated. Six hub target genes were merged in protein-protein interactions (PPI) network analysis, in which existed only one sub-network. Bioinformatics analysis identified an array of affected signaling pathways involved in the development of epithelial and endothelial cells, cell-cell junction assembly, Rap1 signaling pathway, regulation of actin cytoskeleton, and MAPK signaling pathway. Our results revealed the miRNA expression profiles of osteogenic/odontogenic differentiation of hDPSCs under mechanical stress and identified eight miRNAs that were differentially expressed in response to the mechanical stress. Bioinformatics analysis also showed that various signaling pathways were affected by mechanical stress.