Lack of ADAM2, CALR3 and SAGE1 Cancer/Testis Antigen Expression in Lung and Breast Cancer

Characterization of RNA Processing Genes in Colon Cancer for Predicting Clinical Outcomes

Objective

Colon cancer is associated with multiple levels of molecular heterogeneity. RNA processing converts primary transcriptional RNA to mature RNA, which drives tumourigenesis and its maintenance. The characterisation of RNA processing genes in colon cancer urgently needs to be elucidated.

Methods

In this study, we obtained 1033 relevant samples from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases to explore the heterogeneity of RNA processing phenotypes in colon cancer. Firstly, Unsupervised hierarchical cluster analysis detected 4 subtypes with specific clinical outcomes and biological features via analysis of 485 RNA processing genes. Next, we adopted the least absolute shrinkage and selection operator (LASSO) as well as Cox regression model with penalty to characterise RNA processing-related prognostic features.

Results

An RNA processing-related prognostic risk model based on 10 genes including FXR1, MFAP1, RBM17, SAGE1, SNRPA1, SRRM4, ADAD1, DDX52, ERI1, and EXOSC7 was identified finally. A composite prognostic nomogram was constructed by combining this feature with the remaining clinical variables including TNM, age, sex, and stage. Genetic variation, pathway activation, and immune heterogeneity with risk signatures were also analysed via bioinformatics methods. The outcomes indicated that the high-risk subgroup was associated with higher genomic instability, increased proliferative and cycle characteristics, decreased tumour killer CD8+ T cells and poorer clinical prognosis than the low-risk group.

Conclusion

This prognostic classifier based on RNA-edited genes facilitates stratification of colon cancer into specific subgroups according to TNM and clinical outcomes, genetic variation, pathway activation, and immune heterogeneity. It can be used for diagnosis, classification and targeted treatment strategies comparable to current standards in precision medicine. It provides a rationale for elucidation of the role of RNA editing genes and their clinical significance in colon cancer as prognostic markers.

DDX43 mRNA expression and protein levels in relation to clinicopathological profile of breast cancer

BACKGROUND

Breast cancer (BC) is the most often diagnosed cancer in women globally. Cancer cells appear to rely heavily on RNA helicases. DDX43 is one of DEAD- box RNA helicase family members. But, the relationship between clinicopathological, prognostic significance in different BC subtypes and DDX43 expression remains unclear. Therefore, the purpose of this study was to assess the clinicopathological significance of DDX43 protein and mRNA expression in different BC subtypes.

MATERIALS AND METHODS

A total of 80 females newly diagnosed with BC and 20 control females that were age-matched were recruited for this study. DDX43 protein levels were measured by ELISA technique. We used a real-time polymerase chain reaction quantification (real-time PCR) to measure the levels of DDX43 mRNA expression. Levels of DDX43 protein and mRNA expression within BC patients had been compared to those of control subjects and correlated with clinicopathological data.

RESULTS

The mean normalized serum levels of DDX43 protein were slightly higher in control than in both benign and malignant groups, but this result was non-significant. The mean normalized level of DDX43 mRNA expression was higher in the control than in both benign and malignant cases, although the results were not statistically significant and marginally significant, respectively. Moreover, the mean normalized level of DDX43 mRNA expression was significantly higher in benign than in malignant cases. In malignant cases, low DDX43 protein expression was linked to higher nuclear grade and invasive duct carcinoma (IDC), whereas high mRNA expression was linked to the aggressive types of breast cancer such as TNBC, higher tumor and nuclear grades.

CONCLUSION

This study explored the potential of using blood DDX43 mRNA expression or protein levels, or both in clinical settings as a marker of disease progression in human breast cancer. DDX43 mRNA expression proposes a less invasive method for discriminating benign from malignant BC.

Cancer-Testis Gene Biomarkers Discovered in Colon Cancer Patients

In Saudi Arabia, colon cancer (CC) is the most prevalent cancer in men and the third most common cancer in women. Rather than being detected through screening programs, most CC cases are diagnosed mainly during clinical exams. Because of the slow growth of CC and its ability to be treated at an early stage, screening for CC can reduce the incidence of death and mortality. Consequently, there is an urgent need to identify a potential new cancer-specific biomarker for detecting early illness. Much research has been conducted on distinct antigen classes as potential new cancer-specific biomarkers for the early identification of malignancy. The cancer-testis antigens (CTAs) are one such category of antigens, with protein presence largely normally confined to human germ line cells in the testis and aberrantly produced in some cancer cells. CTAs are potentially valuable for use as cancer biomarkers and in cancer therapeutics due to their distinctive expression pattern. The aim of this current study was to identify potential cancer-testis (CT) gene biomarkers in Saudi Arabian CC patients. In this study, a total of 20 matching CC and normal colon (NC) tissues were obtained from the Saudi population. Any genes that showed expression in CC tissues but not in matching NC tissues were subsequently verified for mRNA expression in eight breast and eight leukemia malignancies using RT-PCR to determine the specificity of any CC biomarkers. CTAG1A, SPZ1, LYZL6, SCP2D1, TEX33, and TKTL2 genes were expressed in varying numbers of CC tissues compared to no measurable expressions in all NC tissue specimens, making these genes suitable potential candidates for CC markers. The most frequently expressed CT genes in CC patients were CTAG1A (35%) and SCP2D1 (35%), followed by TKTL2 (25%), SPZ1 (20%), LYZL6 (15%), and TEX33 (5%). The LYZL6 gene shows a weak RT-PCR product in 25% of breast cancer (BC) patients but not in leukemia patients. The SCP2D1 gene appears to display expression in all leukemia patients but not in the BC patients. TKTL2 expression was also observed in 50% of leukemia samples but not in the BC samples. More experiments at the protein level and with a larger cohort of patients are required to evaluate this finding.

Calreticulin (CALR)-induced activation of NF-ĸB signaling pathway boosts lung cancer cell proliferation

Calreticulin (CALR) is known to be aberrantly expressed in lung though the etiology underlying this phenomenon remains undetermined. The (Cancer Genome Atlas) databases were adopted to evaluate the expression status of CALR in pan-cancer, including Lung adenocarcinoma (LUAD) and Lung squamous cell carcinoma (LUSC) accompanied with Genotype-Tissue Expression project (GETx) database. Receiver operating characteristic (ROC) curves and Kaplan-Meier survival curve were plotted to assess its clinical significance in lung cancer. CCK8 and colony formation assays were conducted in addition to in vivo assays. The impact of CALR expression on NF-ĸB-mediated luciferase activity was detected by Luciferase assays. The regulatory relationship between CALR and NF-ĸB was further verified by NF-ĸB inhibitor treatment. LUAD and LUSC tissues reflected marked elevation in the mRNA levels of CALR. ROC analysis showed that CALR expression had a diagnostic value for LUAD or LUSC patients. High-CARL patients demonstrated inferior survival compared to that of Low-CALR patients. Functional assays revealed increased proliferative behaviors of A549 and H1299 cells associated with highly amplified while CALR gene inactivation could reduce the proliferation of both cells. CALR depletion decreased xenograft tumor growth. NF-ĸB transcriptional activity was found to be stimulated with CALR overexpression and reduced in CALR-deficient lung cancer cells, thereby clearly indicating CALR-dependent NF-ĸB activation. NF-ĸB specific inhibitors further validated enhanced NF-ĸB activity mediated by CALR overexpression. Conclusively, our results the role of CALR in lung cancer cells, indicating that highly expressed CALR proliferation at least by activation of NF-ĸB signaling pathway.

SAGE1: a Potential Target Antigen for Lung Cancer T-Cell Immunotherapy

A fundamental understanding of cancer-specific antigens is crucial for successful T-cell immunotherapy. Sarcoma antigen 1 (SAGE1) is a cancer/testis antigen that has not yet been verified for T-cell immunotherapy applications. Here, we examined SAGE1 RNA expression and carried out IHC analyses, revealing that SAGE1 is expressed in 50% of non-small cell lung-cancer samples (n = 40). To verify the immunogenicity of SAGE1, we discovered a novel HLA-A*24:02 (HLA-A24)-restricted SAGE1 epitope (SAGE1_597-606, VFSTAPPAFI) using mass spectrometry and identified SAGE1_597-606-specific T-cell clones and T-cell receptors (TCR) from peripheral bloods of HLA-A24⁺ donors. The highest affinity TCR VF3 (K_D = 4.3 μM) demonstrated the highest antitumor potency. Moreover, VF3-transduced T cells mediated the efficient killing of HLA-A24⁺/SAGE1⁺ tumor cells in vitro and effectively inhibited the growth of lung cancer xenografts in mice. Together, our data suggest that SAGE1 could be a target for T-cell immunotherapies against lung cancer, while its specific TCRs could be candidates for developing reagents to treat SAGE1⁺ tumors.

Immunohistochemical Detection of Cancer-Testis Antigen PRAME

Cancer-testis (CT) antigens were identified by their ability to elicit T- or B-cell immune responses in the autologous host. They are typically expressed in a wide variety of neoplasms and in normal adult tissues are restricted to testicular germ cells. PReferentially expressed Antigen of Melanoma (PRAME) is a member of the family of nonclassical CT antigens being expressed in a few other normal tissues besides testis. Interestingly, knowledge about the protein expression of many CT antigens is still incomplete due to the limited availability of reagents for their immunohistochemical detection. Here, we tested several commercially available serological reagents and identified a monoclonal antibody suitable for the immunohistochemical detection of PRAME in formalin-fixed paraffin-embedded specimens. We also tested a wide array of normal and neoplastic tissues. PRAME protein expression in normal tissues is congruent with original molecular data being present in the testis, and at low levels in the endometrium, adrenal cortex, and adult as well as fetal ovary. In tumors, there is diffuse PRAME immunoreactivity in most metastatic melanomas, myxoid liposarcomas, and synovial sarcomas. Other neoplasms such as seminomas and carcinomas of various origins including endometrial, serous ovarian, mammary ductal, lung, and renal showed an intermediate proportion of cases and variable extent of tumor cells positive for PRAME protein expression. As seen with other CT antigens, hepatocellular and colorectal carcinoma, Leydig cell tumors, mesothelioma, and leiomyosarcoma are poor expressers of PRAME.

The Cancer/Testis Antigen Gene VCX2 Is Rarely Expressed in Malignancies but Can Be Epigenetically Activated Using DNA Methyltransferase and Histone Deacetylase Inhibitors

Identification of novel tumor-specific targets is important for the future development of immunotherapeutic strategies using genetically engineered T cells or vaccines. In this study, we characterized the expression of VCX2, a member of the VCX/Y cancer/testis antigen family, in a large panel of normal tissues and tumors from multiple cancer types using immunohistochemical staining and RNA expression data. In normal tissues, VCX2 was detected in the germ cells of the testis at all stages of maturation but not in any somatic tissues. Among malignancies, VCX2 was only found in tumors of a small subset of melanoma patients and thus rarely expressed compared to other cancer/testis antigens such as GAGE and MAGE-A. The expression of VCX2 correlated with that of other VCX/Y genes. Importantly, we found that expression of VCX2 was inversely correlated with promoter methylation and could be activated by treatment with a DNA methyltransferase inhibitor in multiple breast cancer and melanoma cell lines and a breast cancer patient-derived xenograft. The effect could be further potentiated by combining the DNA methyltransferase inhibitor with a histone deacetylase inhibitor. Our results show that the expression of VCX2 can be epigenetically induced in cancer cells and therefore could be an attractive target for immunotherapy of cancer.

Combined RNA/tissue profiling identifies novel Cancer/testis genes

Cancer/Testis (CT) genes are induced in germ cells, repressed in somatic cells, and derepressed in somatic tumors, where these genes can contribute to cancer progression. CT gene identification requires data obtained using standardized protocols and technologies. This is a challenge because data for germ cells, gonads, normal somatic tissues, and a wide range of cancer samples stem from multiple sources and were generated over substantial periods of time. We carried out a GeneChip‐based RNA profiling analysis using our own data for testis and enriched germ cells, data for somatic cancers from the Expression Project for Oncology, and data for normal somatic tissues from the Gene Omnibus Repository. We identified 478 candidate loci that include known CT genes, numerous genes associated with oncogenic processes, and novel candidates that are not referenced in the Cancer/Testis Database (www.cta.lncc.br). We complemented RNA expression data at the protein level for SPESP1, GALNTL5, PDCL2, and C11orf42 using cancer tissue microarrays covering malignant tumors of breast, uterus, thyroid, and kidney, as well as published RNA profiling and immunohistochemical data provided by the Human Protein Atlas (www.proteinatlas.org). We report that combined RNA/tissue profiling identifies novel CT genes that may be of clinical interest as therapeutical targets or biomarkers. Our findings also highlight the challenges of detecting truly germ cell‐specific mRNAs and the proteins they encode in highly heterogenous testicular, somatic, and tumor tissues.

Lack of evidence for a causal role of CALR3 in monogenic cardiomyopathy

The pathogenicity of previously published disease-associated genes and variants is sometimes questionable. Large-scale, population-based sequencing studies have uncovered numerous false assignments of pathogenicity. Misinterpretation of sequence variants may have serious implications for the patients and families involved, as genetic test results are increasingly being used in medical decision making. In this study, we assessed the role of the calreticulin-3 gene (CALR3) in cardiomyopathy. CALR3 has been included in several cardiomyopathy gene panels worldwide. Its inclusion is based on a single publication describing two missense variants in patients with hypertrophic cardiomyopathy. In our national cardiomyopathy cohort (n = 6154), we identified 17 unique, rare heterozygous CALR3 variants in 48 probands. Overall, our patient cohort contained a significantly higher number of rare CALR3 variants compared to the ExAC population (p = 0.0036). However, after removing a potential Dutch founder variant, no statistically significant difference was found (p = 0.89). In nine probands, the CALR3 variant was accompanied by a disease-causing variant in another, well-known cardiomyopathy gene. In three families, the CALR3 variant did not segregate with the disease. Furthermore, we could not demonstrate calreticulin-3 protein expression in myocardial tissues at various ages. On the basis of these findings, it seems highly questionable that variants in CALR3 are a monogenic cause of cardiomyopathy.

Roles of cancer/testis antigens (CTAs) in breast cancer

Breast cancer is the most common cancer diagnosed and is the second leading cause of cancer death among women in the US. For breast cancer, early diagnosis and efficient therapy remains a significant clinical challenge. Therefore, it is necessary to identify novel tumor associated molecules to target for biomarker development and immunotherapy. In this regard, cancer testis antigens (CTAs) have emerged as a potential clinical biomarker targeting immunotherapy for various malignancies due to the nature of its characteristics. CTAs are a group of tumor associated antigens (TAAs) that display normal expression in immune-privileged organs, but display aberrant expression in several types of cancers, particularly in advanced cancers. Investigation of CTAs for the clinical management of breast malignancies indicates that these TAAs have potential roles as novel biomarkers, with increased specificity and sensitivity compared to those currently used in the clinic. Moreover, TAAs could be therapeutic targets for cancer immunotherapy. This review is an attempt to address the promising CTAs in breast cancer and their possible clinical implications as biomarkers and immunotherapeutic targets with particular focus on challenges and future interventions.