Clinical use of serum TRA-1-60 as tumor marker in patients with germ cell cancer

MicroRNA-371a-3p-The Novel Serum Biomarker in Testicular Germ Cell Tumors

INTRODUCTION

Testicular germ cell tumors (TGCTs) are a paradigm for the use of serum tumor markers in clinical management. However, conventional markers such as alpha-fetoprotein (AFP), beta-human chorionic gonadotropin (hCG), and lactate dehydrogenase (LDH) have quite limited sensitivities and specificities. Within the last decade, the microRNA-371a-3p (miR371) emerged as a possible new biomarker with promising features.

AREAS COVERED

This review covers the typical features as well as possible clinical applications of miR371 in TGCT patients, such as initial diagnosis, therapy monitoring, and follow-up. Additionally, technical issues are discussed.

EXPERT OPINION

With a sensitivity of around 90% and specificity >90%, miR371 clearly outperforms the classical serum tumor markers in TGCTs. The unique features of the test involve the potential of modifying recent standards of care in TGCT. In particular, miR371 is expected to aid clinical decision-making in scenarios such as discriminating small testicular TGCT masses from benign ones prior to surgery, assessing equivocal lymphadenopathies, and monitoring chemotherapy results. Likewise, it is expected to make follow-up easier by reducing the intensity of examinations and by sparing imaging procedures. Overall, the data presently available are promising, but further prospective studies are required before the test can be implemented in standard clinical care.

Liquid Biopsies in the Clinical Management of Germ Cell Tumor Patients: State-of-the-Art and Future Directions

Liquid biopsies constitute a minimally invasive means of managing cancer patients, entailing early diagnosis, follow-up and prediction of response to therapy. Their use in the germ cell tumor field is invaluable since diagnostic tissue biopsies (which are invasive) are often not performed, and therefore only a presumptive diagnosis can be made, confirmed upon examination of the surgical specimen. Herein, we provide an overall review of the current liquid biopsy-based biomarkers of this disease, including the classical, routinely used serum tumor markers—the promising microRNAs rapidly approaching the introduction into clinical practice—but also cell-free DNA markers (including DNA methylation) and circulating tumor cells. Finally, and importantly, we also explore novel strategies and challenges for liquid biopsy markers and methodologies, providing a critical view of the future directions for liquid biopsy tests in this field, highlighting gaps and unanswered questions.

Identification and validation of a five apoptosis-related genes signature for prediction of disease-free survival for testicular germ cell tumors

Background

More and more studies have paid attention to the role of apoptosis in tumorigenesis. A variety of apoptosis-related genes (ARGs) are related to tumor progression and resistance to chemotherapy drugs. Therefore, this study aims to establish a prognostic marker for ARG-based testicular germ cell tumors (TCGT).

Methods

TCGT sequencing data and clinical information were downloaded from The Cancer Genome Atlas (TCGA) database and GEO database. The sequencing data of normal tissues came from the GTEx database. Through univariate COX, LASSO, and multiple COX regression analyses, we screened out key ARGs related to prognosis and constructed a risk signature and a prognostic nomogram. Finally, we performed internal and external verification to verify the signature we have established.

Results

Five ARGs, including CHGA, LPCAT1, PPP1CA, PSMB5, UBR2 were selected out and utilized to establish a novel signature. Based on this signature, TCGT patients were divided into high-risk groups and low-risk groups. The results showed that the disease-free survival (DFS) of patients in the high-risk group was lower than that in the low-risk group (P=0.02268). The subsequent univariate and multivariate Cox regression analysis further proved that the features we established are valuable independent prognostic factors (P<0.05). Also, a prognostic nomogram was created to visualize the relationship between various prognostic-related factors and the 1-, 3-, and 5-year DFS of TCGT in the TCGA cohort.

Conclusions

We constructed a new nomogram based on ARGs to predict the risk of testicular tumor recurrence. It can help clinicians better and more intuitively predict the survival of patients.

Glycan Analysis as Biomarkers for Testicular Cancer

The U.S. Preventive Services Task Force does not recommend routine screening for testicular cancer (TC) in asymptomatic men, essentially because serological testicular cancer (TC) biomarkers are not reliable. The main reason is that two of the most important TC biomarkers, α-fetoprotein (AFP) and human chorionic gonadotropin (hCG), are not produced solely due to TC. Moreover, up to 40% of patients with TC do not have elevated serological biomarkers, which is why serial imaging with CT is the chief means of monitoring progress. On the other hand, exposure to radiation can lead to an increased risk of secondary malignancies. This review provides the first comprehensive account of the applicability of protein glycoprofiling as a promising biomarker for TC with applications in disease diagnostics, monitoring and recurrence evaluation. The review first deals with the description and classification of TC. Secondly, the limitations of current TC biomarkers such as hCG, AFP and lactate dehydrogenase are provided together with an extensive overview of the glycosylation of hCG and AFP related to TC. The final part of the review summarises the potential of glycan changes on either hCG and AFP as TC biomarkers for diagnostics and prognostics purposes, and for disease recurrence evaluation. Finally, an analysis of glycans in serum and tissues as TC biomarkers is also provided.

Testicular Cancer Biomarkers: A Role for Precision Medicine in Testicular Cancer

Testicular germ cell tumors (TGCTs) represent the most common solid tumors among men aged 15 to 34 years. Fortunately, recent advances have made testicular cancer a highly curable disease. Despite the high cure rates, there are still several areas in testis cancer care where treatment decisions are controversial and guided only with clinical factors and historic serum tumor markers. Unfortunately, unlike other genitourinary malignancies, modern research techniques have not been widely tested or applied to germ cell tumors, perhaps as a result of excellent prognosis in this cohort of young men. Despite this, there remain numerous challenges and pitfalls in testis cancer care that need to be addressed. A reliable set of biomarkers could be extremely useful in helping risk-stratify patients, detect relapse early, guide surgical decision-making, and tailor follow-up. Current tumor markers (Alpha-fetoprotein, human chorionic gonadotrophin, and lactate dehydrogenase) have low accuracy and low sensitivity when used not only as diagnostic but also as prognostic and predictive markers. In twenty-first century medicine, there is a role for further prognostic stratification and the development of novel biomarkers that offer greater sensitivity and specificity for TGCTs. Despite the initial promising results, the majority of preclinical biomarkers do not, as yet have a proven validated role in clinical practice, and future prospective trials are needed to support and confirm the results of cohort studies. In this narrative review, we aimed to highlight the recent innovations in the development and implementation of novel testicular tumor markers and discuss their clinical applications and limitations in the management of this disease.

Role of biochemical markers in testicular cancer: diagnosis, staging, and surveillance

Testis cancer is one of the few solid organ malignancies for which reliable serum tumor markers are available to help guide disease management. Human chorionic gonadotropin, alpha fetoprotein, and lactate dehydrogenase play crucial roles in diagnosis, staging, prognosis, monitoring treatment response, and surveillance of seminomatous and nonseminomatous germ cell tumors. Herein we discuss the clinical applications of germ cell tumor markers, the limitations of these markers in the management of this disease, and additional serum molecules that have been identified with potential roles as novel germ cell tumor markers.

Application of stem cell markers in search for neoplastic germ cells in dysgenetic gonads, extragonadal tumours, and in semen of infertile men

Germ cell tumours (GCTs) are a complex entity. Current areas of attention include early detection and avoidance of unnecessary over-treatment. Novel findings regarding diagnosis of GCTs located in various anatomical sites are described, particularly testicular GCTs and their common progenitor, carcinoma in situ (CIS). Recognition of CIS enables intervention before tumour development, but nevertheless, testicular GCTs are sporadically diagnosed at the pre-invasive stage where minimal treatment is necessary. As presence of CIS is asymptomatic, a simple screening method is needed when CIS is suspected (i.e. in males investigated for infertility). To develop approaches for early detection CIS gene expression studies have been performed showing many similarities with embryonic stem cells with confirmation of established markers (i.e. PLAP, OCT-3/4, KIT) and identification of novel markers (i.e. AP-2 gamma, NANOG). We have reported a very promising new approach of AP-2 gamma (or OCT3/4) based immunocytological semen analysis (specificity 93.6%, sensitivity 54.5%). Comparative studies of gonadal/extragonadal GCTs have revealed resemblance pointing towards similar, but not identical, origins. Moreover, infertility and testicular cancer are connected in the 'Testicular Dysgenesis Syndrome' and 25% of contralateral testes from testicular GCT patients harbour dysgenetic features, including impaired spermatogenesis. Thus, recent data have provided potential diagnostic tools including CIS detection in semen, microarray-based tumour classification, additional serological GCT markers, and novel stem cell markers for immunohistochemical diagnosis of gonadal and extragonadal GCTs. Many CIS candidate genes are yet uninvestigated, and information from these could increase knowledge about CIS tumour initiation/progression and be used for optimisation of a non-invasive detection method.

The TRA-1-60 and TRA-1-81 human pluripotent stem cell markers are expressed on podocalyxin in embryonal carcinoma

We have previously identified the cell adhesion protein podocalyxin expressed in a human pluripotent stem cell, embryonal carcinoma (EC), which is a malignant germ cell. Podocalyxin is a heavily glycosylated membrane protein with amino acid sequence homology to the hematopoietic stem cell marker CD34. Since the initial discovery of podocalyxin in a cancerous stem cell, numerous new studies have identified podocalyxin in many different human cancers and in embryonic stem cells lines (ES) derived from human embryos. Embryonal carcinoma, as do all human pluripotent stem cells, expresses TRA-1-60 and TRA-1-81 antigens, and although their molecular identities are unknown, they are commonly used as markers of undifferentiated pluripotent human stem cells. We report here that purified podocalyxin from embryonal carcinoma has binding activity with the TRA-1-60 and TRA-1-81 antibodies. Embryonal carcinoma cells treated with retinoic acid undergo differentiation and lose the TRA-1-60/TRA-1-81 markers from their plasma membrane surface. We show that podocalyxin is modified in the retinoic acid-treated cells and has an apparent molecular mass of 170 kDa on protein blots as compared with the apparent 200-kDa molecular weight form of podocalyxin expressed in untreated cells. Furthermore, the modified form of podocalyxin no longer reacts with the TRA-1-60/TRA-1-81 antibodies. Thus, embryonal carcinoma expresses two distinct forms of podocalyxin, and the larger version is a molecular carrier of the human stem cell-defining antigens TRA-1-60 and TRA-1-81.

Human embryonal carcinoma tumor antigen, Gp200/GCTM-2, is podocalyxin

We previously characterized a peanut agglutinin-binding tumor antigen, gp200, a surface membrane glycoprotein expressed on human embryonal carcinoma, a malignant stem cell of testicular tumors. Gp200 is remarkably similar to another embryonal carcinoma antigen, GCTM-2, a cell differentiation marker that is also detected in blood of testis cancer patients, yet neither molecular identity is known. We now report the identity of gp200 as podocalyxin. Protein sequence results of gp200 peptides match with podocalyxin sequence. Furthermore, two distinct monoclonal antibodies, specific for podocalyxin, react positively with gp200. Therefore, gp200 is a testicular tumor form of podocalyxin, a surface membrane glycoprotein that was originally discovered as a scaffolding extracellular matrix protein of kidney podocyte cells. Podocalyxin is also expressed on subsets of hematopoietic cells where it has a putative function as a cell adhesion protein. This is the first report of podocalyxin expression on malignant cells.