Biological markers of cisplatin resistance in advanced testicular germ cell tumours

Introduction

Germ cell tumours (GCTs) of the testis show exquisite sensitivity to treatment with cisplatin. Despite the high cure rates provided by platinum-based chemotherapy, 10?C20% of patients die from progressive disease. Although various cellular pathways may influence cisplatin efficacy, their actual impact has not been comprehensively investigated in advanced GCTs. The objective of the present study was to clarify the role of the expression status of proteins involved in the Rb and p53 tumour suppressor pathways in sensitivity and resistance of GCTs to cisplatinbased chemotherapy.

Materials and methods

Paraffin-embedded tumour tissues from 84 patients with advanced GCT treated with cisplatinbased chemotherapy were analysed. Immunohistochemical expression of proteins p53 and mdm2, and the G1-phase cyclins D1 and D2 (CD1 and CD2) was assessed and correlated with the clinical course.

Results

The percentages of positive expression of p53, mdm2, CD1 and CD2 were 56, 57, 37.5 and 55%, respectively. From univariate analysis, there was no significant association between p53, mdm2 or CD1 expression and outcome. Instead, positive CD2 expression was found to be marginally associated with shorter median duration of progression-free survival (PFS) (p=0.06). In multivariate analysis, none of the molecular markers retained statistical significance with treatment response or survival.

Conclusions

Tissular expression of p53, mdm2 and CD1 is not associated with prognosis or treatment response in patients with advanced GCT. Aberrant CD2 expression appears to further determine a shorter PFS. Larger and further studies are required to validate CD2 as a marker of cisplatin resistance.     

Human germ cell tumours: expression of gamma-glutamyl transpeptidase and sensitivity to cisplatin.

Previous studies have shown that the enzyme-glutamyl transpeptidase (GGT) is essential for the nephrotoxicity of cisplatin. This study was designed to determine whether GGT activity is necessary for the therapeutic effect of the drug. The relationship between GGT expression and clinical response to platinum-based chemotherapy was examined in 41 human germ cell tumours. Sections of formalin-fixed, paraffin-embedded tumours were immunohistochemically stained with an antibody directed against human GGT. There was no expression of GGT in any of the 17 seminomas or four dysgerminomas; whereas, 12/12 ovarian yolk sac tumours and 4/4 embryonal carcinomas of the testis were GGT-positive. In stage I tumours fewer tumour cells expressed GGT than in later stage tumours. In four germ cell tumours of mixed histology, the seminomatous and dysgerminoma areas were GGT-negative while the areas of the tumour with yolk sac or embryonal histology contained GGT-positive tumour cells. The patients with seminomas or dysgerminomas who were treated with cisplatin-based chemotherapy, all had a complete response despite the absence of GGT expression in these tumours. Fifteen of the 16 patients with yolk sac or embryonal carcinomas received cisplatin-based chemotherapy following surgery. Twelve had a complete response, while three failed to respond to platinum-based therapy. There was no correlation between the level of GGT-expression and response to therapy in this group. Three of the four patients with tumours of mixed histology were treated with cisplatin-based therapy, and had a complete response. Therefore, expression of GGT is not necessary for the therapeutic effect of cisplatin in germ cell tumours. The results from this study suggest that systemic inhibition of GGT would inhibit the nephrotoxic side-effect of cisplatin without interfering with its activity towards germ cell tumours.     

Telomeric length variation in human testicular germ cell tumours

Telomeric length was studied in 5 cases of human testicular germ cell rumours by measuring the length of the terminal restriction fragments (TRFs) containing the (TTAGCG)(n) sequence. Mean TRF length in human placenta used as a source of reference DNA for assessing the effect of cellular ageing was 14 kbp. TRF length in two classical seminomas and a mixed embryonal carcinoma/atypical seminoma ranged from 4 to 14 kbp and from 4 to 23 kbp, respectively, with the same mean value of 9 kbp in both tumour types. In a mixed teratoma/embryonal carcinoma, telomeric length ranged from 14 to 27 kbp with a mean of 20 kbp. In the single case of spermatocytic seminoma studied, telomeric length was up to 100 kbp with a distinct sharp band at similar to 50 kbp, representing the longest, homogeneous telomeres found so far.     

Bone disease in testicular and extragonadal germ cell tumours

Of 297 patients with metastatic testicular and extragonadal germ cell tumours (GCT), bone involvement was detected clinically in 3% (7/251) of those at first presentation and in 9% (4/46) of relapsed cases. This difference was not statistically significant (95% confidence limits -2%; +14%). Concurrent systemic metastases, commonly involving lung (7/11 cases) and para-aortic lymph nodes (6/11), were present in all patients with bone disease. All affected patients had localized bone pain and lumbar spine was the most frequent site involved (9/11). Spinal cord compression occurred in two patients while a third developed progressive vertebral collapse after chemotherapy and required extensive surgical reconstruction. At median follow-up of 4 years, survival among patients presenting with bone disease (6/7) was similar to overall survival in the whole group (84%) and appeared better than in those with liver (18/26, 69%) or central nervous system (6/9) metastases at presentation. Back pain in metastatic germ cell tumours is often due to retroperitoneal lymphadenopathy but lumbar spine osseus metastases must be recognized early if severe potential complications, such as spinal cord compression, are to be avoided. In this series, bone metastases were not seen in the absence of widespread systemic disease suggesting all solitary bony lesions in GCT patients should be biopsied.     

Microsatellite instability in human testicular germ cell tumours.

DNA samples obtained from 29 testicular germ cell tumours have been screened for instability at nine different microsatellite sequences consisting of dinucleotide, trinucleotide and tetranucleotide loci. Overall, in tumours from six (21%) patients we found abnormalities in at least one of the loci examined. Mutation was most frequently found in tetranucleotide and trinucleotide repeats with only a low proportion of alterations in dinucleotide repeats. This pattern of instability is distinct from that reported in colorectal cancer and other cancers that have a high level of alterations in dinucleotide repeats.     

Molecular mechanisms behind the resistance of cisplatin in germ cell tumours

Cisplatin has been one of the principal chemotherapy agents for the last 30 years and is still used widely in the treatment of testicular, ovarian, lung, head and neck, bladder and several other tumours. Resistance to chemotherapeutic agents is a major obstacle for successful treatment. Treatment effect on germ cell tumours (GCTs) is more successful than in adults suffering from almost any other solid tumour, but resistance still appears in 20% of patients with metastatic disease. However, because of the young age of patients and few data regarding the process of becoming resistant, this situation is still a challenge. In this review we are going to analyse the published literature on cisplatin resistance in GCTs and explain the initiatives that the Spanish Germ Cell Cancer Group (GG) is taking to try to elucidate the molecular mechanisms behind this process.     

Management of clinical stage I testicular germ cell tumours

Testicular germ-cell cancer is the most frequent malignancy in young men. In 80% of case no metastasis is observed at diagnosis. Orchidectomy is the initial therapeutic intervention. In case of a pure seminoma, three treatment options should be discussed after surgery : radiotherapy with a limited dose and volume, surveillance, and chemotherapy by single-agent carboplatin. In non-seminomatous germ cell tumour three options should also be considered : surveillance, chemotherapy (two cycles of the BEP regimen) or retroperitoneal lymph node dissection. The strategy should be chosen taking into account predictive factors of relapse and the patient willing. Whatever the strategy, the cure rate is about 99%.     

Clinical and genetic aspects of testicular germ cell tumours

In this paper we review clinical and genetic aspects of testicular germ cell tumours (TGCTs). TGCT is the most common type of malignant disorder in men aged 15-40 years. Its incidence has increased sharply in recent years. Fortunately, survival of patients with TGCT has improved enormously, which can chiefly be attributed to the cisplatin-based polychemotherapy that was introduced in the nineteen eighties to treat patients with metastasized TGCT. In addition, new strategies have been developed in the surgical approach to metastasized/non-metastasized TGCT and alterations have been made to the radiotherapy technique and radiation dose for seminoma. Family history of TGCT is among the strongest risk factors for this tumour type. Although this fact and others suggest the existence of genetic predisposition to develop TGCT, no germline mutations conferring high risk of developing TGCT have been identified so far. A small deletion, referred to as gr/gr, identified on the Y chromosome is probably associated with only a modest increase in TGCT risk, and linkage of familial TGCT to the Xq27 region has not been confirmed yet. Whether highly penetrant TGCT-predisposing mutations truly exist or familial clustering of TGCT can be explained by combinations of weak predispositions, shared in utero or postnatal risks factors and coincidental somatic mutations is an intriguing puzzle, still waiting to be solved.     

Long-term sequelae of treatment for testicular germ cell tumours

Seventy-four patients previously treated in our department for germ cell tumour of the testis underwent a series of tests to determine the frequency of long-term therapeutic complications. All had received cisplatin-based chemotherapy as part of their treatment. There was a significant deterioration in renal function throughout the group. Eighteen (24%) had supine blood pressure greater than systolic 140 mmHg or diastolic 90 mmHg after treatment but hypertension did not correlate with renal impairment. Raynaud's phenomenon was common after chemotherapy (26/74) as was persistent sensory neuropathy (23/74). Although 34% had testosterone levels below the normal range, only six patients had a low free testosterone index with one testis still in situ; 18 patients have fathered children after chemotherapy. Approximately half of the patients completed a psychosexual questionnaire and some 30% of them admitted to sexual problems which they attributed to their treatment. Long-term sequelae of cisplatin-based chemotherapy for testicular malignancy are frequent and persistent, and follow-up of these patients should include prospective measurement of changes in blood pressure.     

Glycolipids of human primary testicular germ cell tumours.

The glycolipid content of human non-seminomatous germ cell tumour cell lines correlates with their differentiation lineage. To analyse whether this reflects the situation in primary tumours, we studied five embryonal carcinomas, five yolk sac tumours and nine (mixed) non-seminomas, using thin-layer chromatography and carbohydrate immunostaining. We also analysed the glycolipid content of 19 seminomas to reveal their relationship with non-seminomas. Lactosylceramide (CDH) was detected in all embryonal carcinomas, but in fewer than half of the seminomas. Seminomas and embryonal carcinomas contained globoseries glycolipids, including globotriosylceramide (Gb3), globoside (Gb4), galactosy globoside (Gb5) and sialy1 galactosyl globoside (GL7). The lacto-series glycolipid Le(x) was found in all embryonal carcinomas, but only in one seminoma. Gangliosides GD3 and GT3 were detected in many seminomas, but rarely in embryonal carcinomas. Yolk sac tumours displayed a heterogeneous glycolipid profile. Compared with seminomas and pure embryonal carcinomas, differentiated non-seminomas had reduced levels of globo-series glycolipids, especially Gb3 and Gb5, whereas CDH, Le(x), GD3 and GT3 were found in the majority of cases. Thus, the glycolipid content of non-seminoma cell lines reflects the situation in primary tumours. Globo-series glycolipids are similarly expressed in seminomas and embryonal carcinomas. The expression of Gb3 and Gb5 is reduced in non-seminomas upon differentiation. Le(x) expression in non-seminomas, including embryonal carcinomas, allows discrimination from seminomas. Expression of gangliosides in seminomas might indicate their maturation from ganglioside-negative precursor cells. Reprogramming of these precursors would result in the formation of Le(x)-expressing embryonal carcinomas.     

Somatic mutations of KIT in familial testicular germ cell tumours

Somatic mutations of the KIT gene have been reported in mast cell diseases and gastrointestinal stromal tumours. Recently, they have also been found in mediastinal and testicular germ cell tumours (TGCTs), particularly in cases with bilateral disease. We screened the KIT coding sequence (except exon 1) for germline mutations in 240 pedigrees with two or more cases of TGCT. No germline mutations were found. Exons 10, 11 and 17 of KIT were examined for somatic mutations in 123 TGCT from 93 multiple-case testicular cancer families. Five somatic mutations were identified; four were missense amino-acid substitutions in exon 17 and one was a 12 bp in-frame deletion in exon 11. Two of seven TGCT from cases with bilateral disease carried KIT mutations compared with three out of 116 unilateral cases (P=0.026). The results indicate that somatic KIT mutations are implicated in the development of a minority of familial as well as sporadic TGCT. They also lend support to the hypothesis that KIT mutations primarily take place during embryogenesis such that primordial germ cells with KIT mutations are distributed to both testes.     

Association between ERCC1 and XPA expression and polymorphisms and the response to cisplatin in testicular germ cell tumours

Background:

Cisplatin cures over 80% of testicular germ cell tumours (TGCTs), and nucleotide-excision repair (NER) modifies the sensitivity to cisplatin. We explored the association between NER proteins and their polymorphisms with cisplatin sensitivity (CPS) and overall survival (OS) of patients with non-seminomatous (ns)-TGCTs.

Methods:

The expression of ERCC1 and XPA and the presence of γH2AX were evaluated in cancer cell lines and in fresh ns-TGCTs. The ERCC1 protein was also determined in ns-TGCTs. The differences between CPS and non-CPS cell lines and patients were analysed by Student''s t- or χ²-tests. The differences in OS were analysed using the log-rank test, and the hazard ratios (HRs) were calculated using the Cox model.

Results:

High ERCC1 expression was observed in the non-CPS cells, and both ERCC1 and γH2AX expressions were augmented after cisplatin treatment. Increased ERCC1 expression was also identified in non-CPS patients. Neither polymorphism was associated with either CPS or OS. The presence of ERCC1 was associated with non-CPS (P=0.05) and adjusted in the prognosis groups. The HR in ERCC1-negative and non-CPS patients was >14.43, and in ERCC1-positive and non-CPS patients the HR was >11.86 (P<0.001).

Conclusions:

High levels of ERCC1 were associated with non-CPS, suggesting that ERCC1 could be used as a potential indicator of the response to cisplatin and prognosis in ns-TGCTs.     

Role of MEK/ERK pathway in the MAD2-mediated cisplatin sensitivity in testicular germ cell tumour cells

Testicular germ cell tumour (TGCT) is the most common malignancy in young males. Although most TGCTs are sensitive to cisplatin-based chemotherapy, significant numbers of TGCT patients still relapse and die each year because of the development of resistance to cisplatin. Previously, we first reported that a key regulator of the mitotic checkpoint, mitotic arrest deficient-2 (MAD2), was a mediator of cisplatin sensitivity in human cancer cells. In this study, we investigated whether MAD2 played a role in cellular sensitivity to cisplatin in TGCT cells and the underlying molecular mechanisms responsible. Using 10 TGCT cell lines, we found that increased MAD2 expression was correlated with cellular sensitivity to cisplatin, which was associated with activation of the MEK pathway. Treatment of cells expressing high levels of MAD2 with an MEK inhibitor, U0126, led to cellular protection against cisplatin-induced apoptosis. Inactivation of MAD2 by transfecting a dominant-negative construct in TGCT cells with high levels of MAD2 resulted in the suppression of MEK pathway and resistance to cisplatin-induced cell death. These results support previous suggestion on the involvement of mitotic checkpoint in DNA damage response in human cancer cells and demonstrate a possible molecular mechanism responsible for the MAD2-mediated sensitivity to cisplatin in TGCT cells. Our results also suggest that downregulation of MAD2 may be an indicator for identification of TGCT cancer cells that are potentially resistant to cisplatin-based therapy.     

Genomic copy number and expression patterns in testicular germ cell tumours

Testicular germ cell tumours of adults and adolescents (TGCT) include seminomas (SE) and nonseminomas (NS), with spermatocytic seminomas (SSE) representing a distinct entity in older men. SE and NS have gain of 12p material in all cases, whereas SSE are associated with overrepresentation of chromosome 9. Here, we compare at the chromosomal level, copy number imbalances with global expression changes, identified by comparative expressed sequence hybridisation analyses, in seven SE, one combined tumour, seven NS and seven cell lines. Positive correlations were found consistent with copy number as a main driver of expression change, despite reported differences in methylation status in SE and NS. Analysis of chromosomal copy number and expression data could not distinguish between SE and NS, in-keeping with a similar genetic pathogenesis. However, increased expression from 4q22, 5q23.2 and 9p21 distinguished SSE from SE and NS and decreased copy number and expression from 2q36-q37 and 6q24 was a specific feature of NS-derived cell lines. Our analysis also highlights 19 regions with both copy number and expression imbalances in greater than 40% of cases. Mining available expression array data identified genes from these regions as candidates for involvement in TGCT development. Supplementary data is available at http://www.crukdmf.icr.ac.uk/array/array.html.     

Mutations of c-kit gene in bilateral testicular germ cell tumours in Japan

About 10-40% of testicular germ cell tumours (TGCTs) have been reported to have activating c-kit gene mutations. A European study group has reported that most bilateral TGCTs from European patients have c-kit mutations at codon 816, although few unilateral cases harbour the mutations. This implies that the presence of a c-kit mutation in a unilateral TGCT predicts the development of TGCT in the contralateral testis (bilateral disease). However, since little is known about on c-kit gene mutational frequencies in bilateral TGCTs from patients of Asian origin, we examined 12 bilateral TGCTs from seven Japanese patients, along with 39 unilateral TGCTs from Japanese patients, for the presence of c-kit mutations. We analyzed c-kit exons 11 and 17 by PCR followed by direct sequencing, and also analyzed the hotspot mutations at codon 816 by loop-hybrid mobility shift assay, a sensitive PCR-based method. We found c-kit mutations in seven of 39 (18%) unilateral TGCTs: two of the seven mutations were in exon 11 and the others, including four point mutations at codon 816, were in exon 17. No mutations, however, were observed in bilateral TGCTs. Thus, the presence of c-kit gene mutations in TGCTs may not be associated with bilateral diseases, at least in Japan.     

Burden of testicular, paratesticular and extragonadal germ cell tumours in Europe

We provide updated estimates of survival, incidence, complete prevalence, and proportion cured for patients with testicular/paratesticular and extragonadal germ cell cancers in Europe, grouped according to the new list of cancer types developed by RARECARE. We collected data, archived in European cancer registries, with vital status information available to 31st December 2003. We analysed 26,000 cases of testicular, paratesticular and extragonadal germ cell cancers diagnosed 1995-2002, estimating that about 15,600 new testicular/paratesticular and 630 new extragonadal cancer cases occurred per year in EU27, with annual incidence rates of 31.5/1,000,000 and 1.27/1,000,000, respectively. Slightly more than 436,000 persons were alive at the beginning of 2008 with a diagnosis of testicular/paratesticular cancer, and about 17,000 with a diagnosis of extragonadal germ cell cancer. Five-year relative survival was 96% for testicular/paratesticular cancer and 71% for extragonadal germ cell cancer; the proportions cured were 95% and 69%, respectively. We found limited variation in survival between European regions except for non-seminomatous testicular cancer, for which five-year relative survival ranged from 86% in Eastern Europe to 96% in Northern Europe. Survival for all cancer types considered decreased with increasing age at diagnosis. Further investigation is required to establish the real reasons for the lower survival in Eastern Europe. Considering the high prevalence of these highly curable cancers, it is important to monitor patients long-term, so as to quantify treatment-related risks and develop treatments having limited impact on quality of life.     

Risk and prognostic significance of metachronous contralateral testicular germ cell tumours

Background:

Testicular germ cell tumour (TGCT) patients are at increased risk of developing a contralateral testicular germ cell tumour (CTGCT). It is unclear whether TGCT treatment affects CTGCT risk.

Methods:

The risk of developing a metachronous CTGCT (a CTGCT diagnosed ⩾6 months after a primary TGCT) and its impact on patient''s prognosis was assessed in a nationwide cohort comprising 3749 TGCT patients treated in the Netherlands during 1965–1995. Standardised incidence ratios (SIRs), comparing CTGCT incidence with TGCT incidence in the general population, and cumulative CTGCT incidence were estimated and CTGCT risk factors assessed, accounting for competing risks.

Results:

Median follow-up was 18.5 years. Seventy-seven metachronous CTGCTs were diagnosed. The SIR for metachronous CTGCTs was 17.6 (95% confidence interval (95% CI) 13.9–22.0). Standardised incidence ratios remained elevated for up to 20 years, while the 20-year cumulative incidence was 2.2% (95% CI 1.8–2.8%). Platinum-based chemotherapy was associated with a lower CTGCT risk among non-seminoma patients (hazard ratio 0.37, 95% CI 0.18–0.72). The CTGCT patients had a 2.3-fold (95% CI 1.3–4.1) increased risk to develop a subsequent non-TGCT cancer and, consequently, a 1.8-fold (95% CI 1.1–2.9) higher risk of death than patients without a CTGCT.

Conclusion:

The TGCT patients remain at increased risk of a CTGCT for up to 20 years. Treatment with platinum-based chemotherapy reduces this risk.     

Selective sensitivity to carboxyamidotriazole by human tumor cell lines with DNA mismatch repair deficiency

We have previously reported that high-dose nifedipine had a selective antiproliferative effect on colon cancer cell lines deficient in DNA mismatch repair (MMR). We hypothesized that carboxyamidotriazole (CAI), a calcium channel blocker, would also have a selective inhibitory effect on colon cancer cell lines with DNA MMR deficiency. In addition, we speculated that this effect may also be seen in cell lines deficient in DNA MMR derived from other tumor types. Fourteen human cancer cell lines with and without DNA MMR derived from carcinomas of the colon, bladder, ovary and prostate were treated with CAI, vehicle or control drugs (nifedipine and 5-flurouracil). The effect of treatment on growth inhibition, invasion, apoptosis and cell cycle progression was assessed. Selective sensitivity to CAI was observed in all cancer cell lines deficient in MMR. Compared with the MMR-proficient cells, the matched deficient cells were significantly more sensitive to the growth inhibitory effect of CAI and nifedipine, but less sensitive to 5-flurouracil. CAI significantly inhibited the invasive ability of MMR-deficient cancer cells compared to 5-flurouracil. CAI induced more apoptosis but similar level of G(2)/M arrest in MMR (hMLH1- or hMSH6-)-deficient colon cancer cells than MMR-proficient counterparts. CAI selectively inhibits proliferation and invasion in MMR-deficient human cancer cell lines. The antitumor effect is at least partly explained by G2/M cell cycle arrest and induction of apoptosis. These findings may have clinical implications directing clinical trials in selectively targeted patients with DNA MMR tumors.     

Paclitaxel-containing high-dose chemotherapy for relapsed or refractory testicular germ cell tumours

High-dose regimes containing etoposide, carboplatin and an oxazaphospharine can salvage 30-40% of patients with relapsed or refractory male germ cell tumours (GCTs). The additional benefit of paclitaxel in such high-dose therapy has not been tested. Between March 1995 and November 2002, 36 male GCT patients were treated with Carbop-EC-T (paclitaxel 75 mg x m(-2), etoposide 450 mg x m(-2), carboplatin AUC 10 on days -7, -5 and -3 and cyclophosphamide 60 mg x kg(-1) on days -5 and -3) followed by peripheral blood stem cell infusion (day 0). The 1-year overall survival rate for all patients is 67% (median follow-up 29 months). For the 24 patients with cisplatin-sensitive disease, the 1-year overall and event-free survivals are 88 and 64%, respectively. For those with cisplatin refractory or absolutely refractory disease, the 1-year overall survival is 25%. In all, 12 patients relapsed at a median duration of 5 months, 11 of whom have died. There were also six treatment-related deaths, five associated with pneumonitis. Pulmonary toxicity has been reported with paclitaxel in other high-dose regimes. Since altering our protocol so that paclitaxel is infused over 24 h with steroid prophylaxis, only one of 18 patients (13 testicular GCTs and five other tumour types) has had a treatment-related death. Our results suggest that Carbop-EC-T may enable a greater proportion of patients with relapsed and refractory GCTs to enter long-term remission.