Detection and enrichment of carcinoma-in-situ cells in semen by an immunomagnetic method using monoclonal antibody M2A

Etiology and early pathogenesis of malignant testicular germ cell tumors: towards possibilities for preinvasive diagnosis

Malignant testicular germ cell tumors (TGCT) are the most frequent cancers in Caucasian males (20-40 years) with an 70% increasing incidence the last 20 years, probably due to combined action of (epi)genetic and (micro)environmental factors. It is expected that TGCT have carcinoma in situ(CIS) as their common precursor, originating from an embryonic germ cell blocked in its maturation process. The overall cure rate of TGCT is more than 90%, however, men surviving TGCT can present long-term side effects of systemic cancer treatment. In contrast, men diagnosed and treated for CIS only continue to live without these long-term side effects. Therefore, early detection of CIS has great health benefits, which will require an informative screening method. This review described the etiology and early pathogenesis of TGCT, as well as the possibilities of early detection and future potential of screening men at risk for TGCT. For screening, a well-defined risk profile based on both genetic and environmental risk factors is needed. Since 2009, several genome wide association studies (GWAS) have been published, reporting on single-nucleotide polymorphisms (SNPs) with significant associations in or near the genes KITLG, SPRY4, BAK1, DMRT1, TERT, ATF7IP, HPGDS, MAD1L1, RFWD3, TEX14, and PPM1E, likely to be related to TGCT development. Prenatal, perinatal, and postnatal environmental factors also influence the onset of CIS. A noninvasive early detection method for CIS would be highly beneficial in a clinical setting, for which specific miRNA detection in semen seems to be very promising. Further research is needed to develop a well-defined TGCT risk profile, based on gene-environment interactions, combined with noninvasive detection method for CIS.

Effect of the MACS technique on rabbit sperm motility

Magnetic-activated cell sorting (MACS) separates apoptotic spermatozoa by the use of annexin V-conjugated nanoparticles which bind to phosphatidylserine that is externalized on the outer leaflet of the sperm plasma membrane. This technique yields two fractions: annexin V-negative (AnV−) and annexin V-positive (AnV+). The aim of the study was to evaluate the effect of MACS application on the motility parameters of rabbit spermatozoa. Rabbit semen samples collected separately from 4 bucks (I, II, III, and IV) were filtered and separated in a MACS system. The semen samples from a control (untreated) group, AnV− and AnV+ fraction were evaluated using CASA system. The experiment was replicated 4 times for each buck. The AnV+ sperm had significantly lower concentration than the AnV− fractions and the control samples (P<0.05 for bucks I, II, III, but not IV). We observed that the proportion of apoptotic spermatozoa in the semen of NZW bucks is about 20%. There was no significant difference in the percentage of motile and progressively motile spermatozoa between the AnVfractions and control samples. In conclusion, the MACS technique has no harmful effect on the rabbit sperm concentration and motility.

Seminal expression of NY-ESO-1 and MAGE-A4 as markers for the testicular cancer

Testicular germ cell tumours (TGCTs) are the most common malignancies in Caucasian young men and their incidence has increased over the past decades. However, a non-invasive test allowing an early diagnosis of TGCT often proves inaccurate. We have previously shown that two Cancer-Testis Antigens (CTA), namely MAGE-A4 and NY-ESO-1, were expressed by TGCT. As exfoliation of carcinoma in situ (CIS) cells or tumour germ cells from testis into seminal fluid can occur, here we studied the expression of the 2 CTA in semen smears of patients with testicular cancer in comparison with healthy men. Using semen smears from healthy controls (n = 65) and patients diagnosed for testicular tumour (n = 57) and immunological staining, we observed expression of MAGE-A4 and NY-ESO-1 proteins in seminal fluid exfoliated cells. We found a highly statistically significant difference in the ratios of stained cells to the total number of round cells between testicular cancer patients and healthy controls. Multivariable analysis, including sperm parameters and immunostaining on sperm smears, shows the improvement. This technique can provide towards testicular cancer diagnosis when it is included in the current testing regime. However, the fact that expression of these markers was not restricted to foetal germ cells led to detection in the semen of a number of healthy subjects. Although the detection of these CTA could be useful to characterize the sub-type of individual TGCTs better, we stress here that the false positive rate precludes the exclusive employment of these CTA for the early detection of testicular neoplasia.

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.

Prenatal development of murine gonads with special reference to germ cell differentiation: a morphological and immunohistochemical study

The prenatal differentiation of male and female gonads of the mouse was investigated both morphologically and immunohistochemically. Sexual dimorphism could be detected as early as 12 days post-coitum (dpc) by the appearance of the primary elements of the tunica albuginea and positive immunoreactivity for anti-Muellerian hormone in the Sertoli cells of the male gonad. Male germ cells passed two waves of mitotic activity, a first wave between 12 and 14 dpc, which is followed by apoptosis of the old germ cell generation, and a second wave between 17 and 20 dpc. Oct-4 was expressed as a juxtanuclear ring in the cytoplasm of germ cells up to 17 dpc. Subsequently, it was down-regulated and completely disappeared in 20 dpc full-term fetuses. By contrast, M2A antigen revealed only a weak immunoreaction in some germ cells of 14 dpc gonads, but exhibited strong signals in all germ cells of 20 dpc full-term fetuses. Therefore, we postulate that, in the mouse, prenatal germ cells represent two populations: the first is immunopositive for Oct-4 and disappeared in full-term fetuses, whereas the second appeared in 14 dpc and is immunopositive for M2A antigen.

Identity of M2A (D2-40) antigen and gp36 (Aggrus, T1A-2, podoplanin) in human developing testis, testicular carcinoma in situ and germ-cell tumours

Testicular germ-cell tumours of young adults are derived from a pre-invasive intratubular lesion, carcinoma in situ (CIS). In a recent genome-wide gene expression screening using cDNA microarrays, we found PDPN over-expressed in CIS compared to normal adult testis. PDPN encodes podoplanin (Aggrus, human gp36, T1A-2), a transmembrane glycoprotein expressed in lymphatic endothelium and various solid tumours. To examine a potential role for PDPN in testicular neoplasms and during testicular development, we investigated its expression pattern during the development of human testis and in a series of testicular CIS, gonadoblastoma and overt germ-cell tumours. We established by RT-PCR and by immunohistochemistry with a gp36 antibody that PDPN mRNA and the protein product were expressed in testes with germ-cell neoplasms but not in the normal adult testis. We also found gp36 expression in early foetal gonocytes and immature Sertoli cells, similar to the expression pattern of M2A antigen, a previously identified marker for CIS and seminoma. This reinforced our previous proposal that M2A (D2-40) antigen was identical to gp36 (podoplanin, Aggrus, T1A-2). Our findings also suggest that podoplanin has a function in developing testis, most likely at the level of cell-cell interactions among pre-meiotic germ cells and immature Sertoli cells.

A subfertile patient diagnosed with testicular carcinoma in situ by immunocytological staining for AP-2γ in semen samples: Case report

The incidence of testicular cancer is rising. Despite a high cure rate, efforts should be made to obtain diagnosis at the pre-invasive intratubular carcinoma in situ (CIS) stage, as the disease is potentially lethal and treatment has severe side-effects, especially regarding reproductive function. CIS diagnosis is presently only possible by a surgical biopsy of the testis. Immunocytological staining for transcription factor activator protein (AP-2gamma), previously identified as a marker for neoplastic germ cells, was performed in centrifuged samples of ejaculates obtained from 104 andrological patients, including patients with testicular cancer and subfertility. Cells positive for AP-2gamma were found only in semen samples from patients diagnosed a priori with testicular neoplasms and, surprisingly, in a 23 year old control subject with oligozoospermia and no symptoms of a germ cell tumour. Testicular biopsies performed during the follow-up of this patient revealed widespread CIS in one testicle, thus proving a potential diagnostic value of the new marker. For the first time, a patient without clinical symptoms of testicular neoplasia was diagnosed at the pre-invasive CIS stage using a new, simple method based on immunocytological staining of a semen sample for AP-2gamma, a novel marker for CIS. The value of this method for diagnostic use in the clinic requires further careful validation in a large series of patients and controls, but the preliminary results are promising.

Leptin and leptin receptor in human seminal plasma and in human spermatozoa

Leptin, a 167 amino acid peptide, is known to influence the gonads via direct and indirect effects. Recent studies provide contradictory proposition about the peripheral impact of leptin in the male gonads. Thus, we examined leptin and its receptors in human seminal plasma and in human ejaculated spermatozoa by Western blot technique and fluorescence microscopy. In seminal plasma we found a free leptin band (16 kDa) by an anti-leptin polyclonal antibody. Incubation of seminal plasma with recombinant leptin caused a statistically significant increase in the amount of free leptin (p < 0.01) and supports this finding. Furthermore, a soluble leptin receptor (145 kDa) was found in human seminal plasma in the same specimen. We also detected a 145-kDa leptin receptor isoform in ejaculated spermatozoa as a possible target of leptin action in the male genital tract, which was localized at the tail of spermatozoa by immunofluorescence microscopy only. This receptor was significantly associated with the intactness of sperm plasma membranes. Spermatozoa with deteriorated membranes contained 49.2 +/- 6.9% leptin receptor signal intensity compared with spermatozoa having intact membranes (p < 0.01). This finding is difficult to interpret and may be caused by a leakage of OB-R due to loss of membrane integrity. In conclusion, these data provide further hints for a peripheral role of leptin in the male genital tract, possibly, by an interaction between leptin and spermatozoa via sperm leptin receptors.

Deterioration of plasma membrane is associated with activated caspases in human spermatozoa

Spermatozoa with deteriorated plasma membranes can be separated by magnetic-activated cell sorting (MACS) after binding superparamagnetic annexin V-conjugated microbeads (ANMBs) to membrane phosphatidylserine (PS). Semen samples from 15 donors and 25 infertile patients were divided into 2 spermatozoal fractions by annexin V-MACS. Activated caspases (aCPs), which mediate degradations of cell quality, were determined by CaspaTag in the 2 subpopulations. Spermatozoa from donors showed lower levels of bound annexin V (3.6% +/- 0.5% vs 11.9% +/- 1.1%; P <.01) and aCPs (21.8% +/- 2.6% vs 43.2% +/- 2.1%; P <.01) than did spermatozoa from infertile patients. MACS resulted in a decrease of spermatozoa with aCPs from 21.8% +/- 2.6% (before separation) to 9.2% +/- 1.4% (in the ANMB-negative fraction) in donors and from 43.2% +/- 2.1% to 18.8% +/- 2.6% in infertile patients (mean +/- SEM; P <.01). Separation effects of the MACS technique were confirmed with flow cytometry using anti-annexin V antibodies and with electron microscopy. ANMB-MACS removes spermatozoa with PS-bound annexin V and produces a higher quality spermatozoal fraction. Spermatozoa with a deteriorated membrane are characterized by an increase in aCPs. A higher percentage of spermatozoa with ANMBs bound to PS and with aCPs were found in infertile patients.

Carcinoma in situ in the testis

Carcinoma in situ (CIS) of the testis is a common precursor of germ-cell tumours in adults and adolescents, with the exception of spermatocytic seminoma. This article reviews existing knowledge on the pathobiology, genetic aspects and epidemiology of CIS, discusses current hypotheses concerning pathogenesis and invasive progression of germ-cell neoplasms and provides guidelines for diagnosis and clinical management of CIS.

Carcinoma in situ of the testis: review of biological and clinical features

Carcinoma in situ of the testis (CIS) is the uniform precursor of testicular germ-cell tumours. Morphologically, CIS consists of large, intratubular, gonocyte-like cells with large nuclei and abundant glycogen. CIS cells are probably derived from primordial germ cells and are supposed to be present in the testis of a future testis cancer patient at the time of birth. CIS cells appear to spread inside the seminiferous tubules until CIS progresses to invasive cancer. Diagnosis is best achieved by surgical biopsy of the testis and subsequent immunohistological staining of placental alkaline phosphatase (PlAP). This enzyme is present in embryonal germ cells, CIS and seminoma as well as several other types of germ-cell tumour but usually not in normal germ cells. CIS is found in testicular tissue adjacent to testicular germ-cell tumours in about 90% of cases, and it is observed in all clinical groups known to be at risk for testicular cancer: cryptorchidism (2% to 4%), infertility (0% to 1%), ambiguous genitalia (25%) and contralateral testis of patients with testicular cancer (5%). Conversely, CIS is found in less than 1% of the normal male population, and this prevalence corresponds well to the life-time risk of testicular cancer in males. If CIS is left untreated, there is a 50% probability of progressing to frank germ-cell neoplasm within 5 years. Localised low-dose radiotherapy to the testis eradicates CIS and germ cells, while Leydig cells are preserved. The patient can thus be spared orchiectomy and hormone supplementation. Currently, dose-reduction studies are looking for the optimal radiation dose, which is expected to be around 14 to 16 Gy. After chemotherapy, there is a cumulative risk of 42% for recurrence of CIS within 10 years. The concept of CIS offers the chance of very early detection of testicular cancer and organ-preserving early treatment.

Characterization and distribution of an oncofetal antigen (M2A antigen) expressed on testicular germ cell tumours

M2A antigen is an oncofetal antigen associated with germ cell neoplasia, present in testis on fetal gonocytes and re-expressed on carcinoma in situ (CIS) and germ cell tumours. We developed a panel of monoclonal antibodies (mAb), M2A (IgG2a), D1-26 (IgG2b) and D2-40 (IgG1), to this antigen in order to characterize its structure and study its distribution among germ cell tumours. M2A antigen was purified by sequential lectin and antibody affinity chromatography and characterized as a monomeric M, 40 000 surface sialoglycoprotein, extensively glycosylated with O-linked carbohydrate structures, but devoid of N-linked sugars. Terminal sialic acid residues were required for reactivity with mAb M2A and D1-26, but not D2-40. Sections of 69 testicular germ cell tumours, fixed in formalin and embedded in paraffin, were stained with mAb D2-40 to examine the distribution of M2A antigen. Uniform membrane staining was observed in seminomas, and focal staining in 69% of embryonal carcinomas, 29% of teratomas and 25% of yolk sac tumours. CIS in the vicinity of all germ cell tumours also displayed uniform membrane staining. The characterization of M2A antigen, and the development of mAb which react with it in conventionally preserved archival specimens, provide important initiatives to study the origin and progression of germ cell neoplasia.

Fluorescence in situ hybridization analysis of chromosome 12 anomalies in semen cells from patients with carcinoma in situ of the testis

Carcinoma in situ (CIS) of the testis is the precursor of seminomas and non-seminomatous germ cell tumours of the adult testis. A marked cytogenetic anomaly, the isochromosome of the short arm of chromosome 12 [i(12p)], has been demonstrated in over 80 per cent of all histological varieties of testicular germ cell tumours (TGCTs). In the remaining group of i(12p)-negative TGCTs, an overrepresentation of chromosome 12p sequences has been found. The i(12p) chromosome and overrepresentation of 12p sequences in CIS cells have also been reported. In order to establish whether numerical and/or structural aberrations of chromosome 12 can be found in CIS cells exfoliated into seminal fluid, semen specimens from ten patients with CIS lesions were investigated using bicolour double fluorescence in situ hybridization (FISH). The two DNA probes used, p alpha 12H8 and YAC 5, specifically detect the centromeric region of chromosome 12 and a subregion, p11.2-p12.1, on the short arm of chromosome 12, respectively. Ejaculates of ten azoospermic or oligozoospermic infertile males, presumably CIS-free, were used as negative controls. Nuclei exhibiting three or more chromosome 12 signals were found to be present in a significantly larger number in the patient samples than in the control samples. Nuclei with five or more chromosome 12 signals were observed in eight out of the ten patients. Morphologically similar arrangements to i(12p) were observed in some of the ejaculates. These results demonstrate the potential of FISH in the early detection of CIS and TGCTs in males at high risk.