Multicentre risk-adapted management for stage I non-seminomatous germ cell tumours

BACKGROUND

The Spanish Germ Cell Group is composed of 60 centres. Our challenge was to define a surveillance protocol that would be safe and suitable regardless of population size or geographic coverage.

METHODS

From January 1994 to January 2004, 589 patients with stage I non-seminomatous germ cell tumours entered a risk-adapted surveillance protocol after orchiectomy. Patients with vascular or local invasion of adjacent structures (231/589; 39%) received two cycles of BE400P (bleomycin 30 U/week, etoposide 100 mg/m2 x4, cisplatinum 25 mg/m2 x4). Other patients (358/589; 61%) were kept on close follow-up (chest X-ray; serum tumour markers: first year every 2 months, second year every 3 months, third year every 4 months; abdominal computed tomography scans at every other outpatient control). The outcomes selected for the study were feasibility, relapse rate and number of patients lost to follow-up and mortality.

RESULTS

Median follow-up was 40 months. In the surveillance group, 21 patients were lost to follow-up. In the chemotherapy group, two patients relapsed at 12 and 14.5 months and they are presently free of disease. In the surveillance group, 71 (19%) patients relapsed, of which 55 (71%) relapsed within the first year. Five (1.4%) patients died of their cancer. Factors associated with relapse were embryonal carcinoma and vascular invasion in patients who refused chemotherapy.

CONCLUSIONS

Our risk-adapted surveillance protocol provided a low rate of recurrences.

Four pregnancies and two deliveries after unilateral orchidectomy and chemotherapy for testicular embryonal carcinoma

This case report describes a 33-year-old patient diagnosed with left-sided testicular embryonic carcinoma with vascular invasion. Unilateral orchiectomy was performed and the patient subsequently underwent chemotherapy. He retained fertility and later fathered healthy children.

Coffee grounds emesis: rare presentation of testicular cancer treated with neoadjuvant chemotherapy

Fewer than 5% of patients with metastatic testicular cancer present with gastrointestinal involvement. Even rarer is testicular metastasis to the duodenum. We present the case of a previously healthy 26-year-old man who had symptomatic gastrointestinal bleeding caused by metastatic testicular cancer. He was treated with orchiectomy, cisplatin-based neoadjuvant chemotherapy, and finally, resection of the residual retroperitoneal mass. We believe that neoadjuvant chemotherapy, followed by surgical debulking, is the appropriate therapeutic sequence when treating an otherwise stable patient with metastatic testicular tumor involving the gastrointestinal tract.

Long-Term Efficacy of Two Cycles of BEP Regimen in High-Risk Stage I Nonseminomatous Testicular Germ Cell Tumors with Embryonal Carcinoma and/or Vascular Invasion*1

OBJECTIVES

To report the long-term impact of two cycles of adjuvant chemotherapy on relapse rates and treatment-related morbidity in high-risk stage I nonseminomatous testicular germ cell tumors (NSGCTT I).

MATERIAL AND METHODS

From April 1987 to September 1997, 40 stage I NSGCTT patients with evidence of vascular invasion and/or embryonal carcinoma (EC) in the orchidectomy specimen were treated with two courses of bleomycin, cisplatin, and etoposide (BEP).

RESULTS

All patients but one (incidental death) were alive after an extended follow-up (median 113.2 months, range 63-189). No patients relapsed but two patients presented a second cancer in the remaining testis. Short-term toxicity was minimal and no long-term toxicity was observed.

CONCLUSION

The present series, with extensive follow-up, demonstrated that the efficacy and toxicity of two cycles of BEP compared well with the results of surveillance strategies or RPLND in high-risk stage I NSGCTT.

Risk-adapted treatment for patients with clinical stage I nonseminomatous germ cell tumor of the testis

OBJECTIVES

To evaluate whether two courses of chemotherapy after orchiectomy in patients with clinical Stage I nonseminomatous germ cell testicular tumor at high risk of relapse will spare patients additional chemotherapy or surgery.

METHODS

High-risk patients had one or more of the following: preorchiectomy alpha-fetoprotein level of 80 ng/dL or greater, 80% embryonal cell carcinoma or greater, or vessel invasion in the primary tumor. Low-risk patients had none of these factors or had 50% teratoma or more without vessel invasion. High-risk patients were offered two 21-day courses of outpatient chemotherapy consisting of carboplatin, etoposide, and bleomycin. Low-risk patients and high-risk patients not receiving chemotherapy were observed.

RESULTS

Of 99 patients, we classified 76 as high risk and 23 as low risk of relapse. All but eight of the high-risk patients received chemotherapy. No patient who underwent chemotherapy developed relapse, although 1 patient with normal biomarkers and a late-appearing mass underwent retroperitoneal lymphadenectomy for mature teratoma. Two of the 23 low-risk patients had disease relapse; both successfully underwent chemotherapy. The nonhematologic toxicity was mild in patients receiving chemotherapy, and no patient required hospitalization. The median follow-up was 38 months (range 9 to 69).

CONCLUSIONS

Two courses of postorchiectomy adjuvant chemotherapy were safe and well tolerated and markedly decreased the relapse rate in high-risk patients with clinical Stage I nonseminomatous germ cell testicular tumor without additional surgery or more protracted chemotherapy. This approach may avoid potential problems with compliance and diminish the cost of scrupulous follow-up. Our results support that surveillance for carefully selected patients at a low risk of relapse is appropriate.

Extragonadal retroperitoneal embryonal carcinoma successfully treated with chemotherapy

A 27-year-old Japanese man visited our hospital for further evaluation of multiple shadows on his chest X-ray. A 6 cm hard mass was palpable in the left lower abdominal region. Histological examination revealed that the lung tumor resected by the video-assisted thoracoscopic surgery was an embryonal carcinoma (EC). He was diagnosed as retroperitoneal EC with multiple lung metastases. He underwent chemotherapy with cisplatin, etoposide, and bleomycin, followed by 3 courses. A curative surgical operation revealed that there were no malignant cells in the lung lesions and primary lesion. This patient responded well to chemotherapy and achieved complete remission by chemotherapy.

Two cycles of carboplatin-based adjuvant chemotherapy for high-risk clinical stage I and stage IM non-seminomatous germ cell tumours of the testis: a HECOG trial

BACKGROUND

We investigated the efficacy and safety of 2 cycles of adjuvant chemotherapy with carboplatin, etoposide and bleomycin (CEB90) in patients with high-risk clinical stage I or stage IM non-seminomatous germ cell tumours (NSGCT).

PATIENTS AND METHODS

A total of 52 consecutive patients (22 patients with high-risk histological features [vascular invasion, presence of embryonal carcinoma, absence of yolk sac tumour] and 30 with tumour marker activity post-orchidectomy-stage IM) were entered into this prospective study. Chemotherapy consisted of carboplatin 400 mg/m2 or AUC 5 (day 1), etoposide 165 mg/m2 (days 1-3) and bleomycin 30 mg (days 1, 8, 15). Chemotherapy was repeated every 3 weeks.

RESULTS

During a median follow-up of 112 months (range, 10 to 174 months), two patietns with stage IM relapsed. These cases had a disseminated, marker-positive germ cell tumour (GCT), extensively involving both liver and lungs in the first case and para-aortic lymph nodes and lung in the second one; both patients died of the tumour after a number of salvage chemotherapy (including high-dose therapy) regimens. Fifty patients (96%) are alive and disease-free. Two cycles of CEB90 were well tolerated and the only side-effects were myelotoxicity and alopecia.

CONCLUSION

Despite the general consensus that ciplatin-based chemotherapy is superior to carboplatin-containing regimens in testicular cancer, 2 cycles of CEB90 may be an equally effective treatment option as adjuvant therapy for high-risk clinical stage I and IM patients.

Extensive surgery in metastatic testicular cancer

Surgery remains an important component in the multimodal treatment of patients with advanced testicular cancer. Recently, however, the indications for post-chemotherapy residual tumor resection have changed. Patients with advanced seminoma very rarely need surgical resection of the residual disease after standard chemotherapy. In contrast, patients with high stage non-seminomatous testis cancer must undergo post-chemotherapy surgery in most cases. Surgical resection in metastatic disease may also be necessary in patients with recurrent tumors, patients with persisting marker elevation during chemotherapy and patients with late relapses. Post-chemotherapy residual tumor resections, "redo"-retroperitoneal tumor operations and other salvage resections are often technically demanding procedures with unusual surgical approaches that require individualized perioperative planning in order to reduce morbidity. This paper summarizes the current indications for post-chemotherapy surgery and discusses various surgical approaches and techniques, perioperative management recommendations, as well as complications of these extensive resection procedures.

Unusual intrathoracic location of a primary germ cell tumour

The primary location of non-metastatic germ cell tumours of the chest is the anterior mediastinal compartment. Germ cell tumour arising from lung parenchyma is one of the rarest conditions in human and only a few cases of choriocarcinomas and yolk sac tumour have been reported to date. Here we report a case of intrapulmonary mixed type germ cell tumour, containing embryonal carcinoma, choriocarcinoma and yolk sac tumour elements. Diagnosis of the lesion was achieved by open thoracotomy and bulk of the tumour was resected by right upper lobectomy.

Alpha-FP normalization as a prognostic factor for mediastinal origin embryonal carcinoma: report of five cases

It is well known that a subgroup of germ cell tumors, embryonal carcinoma of extra-gonadal origin have a poor prognosis. We have encountered five cases of mediastinal embryonal carcinoma treated with high-dose chemotherapy (HD-CT) supported by auto-PBSCT in four, and resection in three. Our cases indicated that normalization of the alpha-FP tumor marker level during standard chemotherapy is a very important factor for cure, and the resection of the residual mass after chemotherapy is indicated due to the great risk of remnant malignant cells despite HD-CT.

A novel signaling pathway of nitric oxide on transcriptional regulation of mouse kappa opioid receptor gene

Nitric oxide (NO) suppressed the transcription of the mouse kappa opioid receptor (KOR) gene, mediated by a rapid downregulation of c-myc gene expression. KOR was constitutively expressed in postnatal day 19 (P19) embryonal carcinoma stem cells and is suppressed by NO donors [sodium nitroprusside (SNP), 3-morpholinosydnonimine-1, and S-nitrosoglutathione] in P19 stem cells within 4 hr. The suppression was reversed by 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, an NO scavenger, but could not be blocked by dithiothreitol, ruling out S-nitrosylation as the underlying mechanism. The suppressive effect of NO on KOR occurred at the level of gene transcription, mediated by E boxes located in promoters I and II of this gene. Protein-DNA complexes that formed on these E boxes contained c-myc; c-myc expression was suppressed by NO in P19 stem cells within 2 hr of treatment. Furthermore, chromatin immunoprecipitation demonstrated reduced c-myc binding to the E boxes and hypoacetylation of histone H3 on the chromatin of endogenous KOR promoters in P19 stem cells treated with SNP. It is proposed that NO regulates KOR at the level of gene transcription, mediated by a rapid suppression of c-myc gene expression and its binding to KOR promoters, and followed by chromatin hypoacetylation of and reduced transcription from KOR promoters in P19 stem cells. A novel pathway mediating the potential interplay between NO and opioid systems is discussed.

DNA topoisomerase I and II expression in drug resistant germ cell tumours

A small number of testicular germ cell tumours are refractory to current chemotherapy regimens. DNA topoisomerase I is the target for several new drugs and a potential candidate treatment for chemorefractory germ cell tumours. DNA topoisomerase II alpha is the target for etoposide, which is currently used regularly in germ cell tumour treatment. The expression of DNA topoisomerase I and II alpha were therefore assessed immunohistochemically in a range of testicular tumours, especially those with persistent malignant elements on retroperitoneal lymph node dissection. Pre-chemotherapy orchidectomy specimens were matched with post-chemotherapy retroperitoneal lymph node dissections to examine changes in expression. There was considerable variation in the expression of topoisomerase I in different tumour types. Both yolk sac tumours and teratoma, mature showed universal expression of topoisomerase I, while 38% of seminomas and 30% of embryonal carcinomas were positive. Strong topoisomerase II alpha expression was found in embryonal carcinoma. There was a negative correlation between topoisomerase I and II alpha expression (P=0.004) and downregulation of topoisomerase II alpha after chemotherapy (P=0.02). Topoisomerase I expression appears to increase in those cases with residual teratoma, mature, but is largely unchanged in those cases remaining as embryonal carcinoma. These results suggest that topoisomerase I inhibitors may be useful in chemorefractory germ cell tumours, especially yolk sac tumours and where there are unresectable residual teratoma, mature deposits.

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

TRA-1-60 antigen has been related to the presence of embryonal germ cell carcinoma (EC) and carcinoma in situ. Our study further investigated the clinical efficacy of TRA-1-60 as a serum tumor marker for germ cell cancer in the testis. Three groups of patients with germ cell tumors were included: Group 1, 34 patients with disseminated disease (24 nonseminomatous germ cell tumors [NSGCT] and 10 seminomatous germ cell tumors [SGCT]); this group of patients were followed during the course of chemotherapy with measurements of TRA-1-60, HCG and AFP; Group 2, 28 patients with Stage I NSGCT (22 with embryonal carcinoma [EC]-component and 6 without EC-component, median follow-up 15 months); and Group 3, 40 patients with Stage I pure SGCT (median follow-up 15 months). Seventy-eight percent of patients with disseminated EC-positive NSGCT had increased levels of TRA-1-60 before chemotherapy. After chemotherapy, levels of TRA-1-60 had dropped significantly (p < 0.01). Levels of TRA-1-60 did not normalize in 15% of NSGCT and 30% of SGCT patients after chemotherapy. This was not associated with recurrent disease. Approximately one-third of patients with Stage I NSGCT had increased values of TRA-1-60 during follow-up without having a relapse. Contrary to earlier reports TRA-1-60 is not at present useful as a tumor marker in patients with germ cell tumors. Although detecting a few early relapses the rate of false positive elevations in the tumor marker makes it unreliable in the clinical setting. Our study did confirm that elevated levels of TRA-1-60 were present in approximately 80% of patients with disseminated EC-positive NSGCT before start of chemotherapy and chemotherapy induced a significant decrease in levels of TRA-1-60. Thus, the TRA-1-60 antigen might still prove clinically useful provided that the reliability of the assay can be increased.

Global gene expression patterns during neural differentiation of P19 embryonic carcinoma cells

The nervous system is composed of many different types of neurons and glia cells. Differentiation of these cell types is regulated by various intrinsic transcriptional programs as well as extrinsic signals. Studies of neural differentiation have been focused on the roles of individual factors. Here we profiled global gene expression patterns during neural differentiation of P19 embryonic carcinoma cells. Grouping of the genes induced during P19 neural differentiation into functional categories reveals a set of important transcription factors and extracellular signaling pathways, many of which are also involved in neural development in vivo. In addition, clustering of the induced genes according to their temporal expression pattern reveals 6 groups of genes, each with distinct kinetics, suggesting the existence of different phases in P19 neural differentiation. Our studies provide a temporal array of global pictures of the gene expression patterns used during neural differentiation. The results of this study provide the framework for subsequent analysis of the effects of various intrinsic and extrinsic factors on neural differentiation.

Cisplatin-induced in vivo differentiation of human embryonal carcinoma

OBJECTIVE

To investigate the differentiation of embryonal carcinoma (EC) by cisplatin, and the underlying mechanism, as untreated metastases of nonseminomatous germ cell tumours rarely consist of fully differentiated mature somatic tissues, but such mature metastases are more common after various treatments, including chemotherapy.

MATERIALS AND METHODS

The TTSC-3 human testicular EC line heterotransplanted into nude mice was used as a target. After treating tumour-bearing mice with intraperitoneal injections of varying doses of cisplatin, the histopathology of the tumours was assessed and various gene expressions in the tumours determined by cDNA-array technology.

RESULTS

When cisplatin at 1 mg/kg/week was injected intraperitoneally into TTSC-3-bearing mice, there was no effect on tumour growth. However, injecting cisplatin at 5 mg/kg/week induced a marked regression of the tumour. In contrast, cisplatin at 3 mg/kg/week had a modest inhibitory effect on tumour growth and induced tumour dormancy. Histological examination showed that 5 weeks after injecting cisplatin (3 mg/kg/week), primitive mesenchymal-like cells increased, and 10 weeks afterward cartilage and well-developed glands (teratoma) were apparent; at > 15 weeks afterward there were no EC cells visible. cDNA probes from reverse-transcribed mRNAs of TTSC-3 treated with cisplatin or saline for 10 weeks were compared to identify genes differentially expressed in cisplatin-treated TTSC-3. Of 1176 different human cDNA transcripts in cisplatin-treated TTSC-3, three genes (tumour necrosis factor receptor 1, caspase 8 and Apaf1), which are associated with apoptosis, were expressed markedly more than after saline injection.

CONCLUSIONS

The intermediate dose of cisplatin inhibited tumour growth of EC by inducing differentiation and enhancing apoptosis-related gene expression. These findings suggest that cisplatin may play a significant role in the differentiation of EC in vivo.

Isolated central nervous system relapse of non-seminomatous germ cell tumour of the testis. A case report and review of the literature

Isolated central nervous system (CNS) relapse of non-seminomatous germ cell tumour (NSGCT) of the testis has been reported in only 12 patients previously. We report a patient with an isolated CNS relapse of NSGCT, following a prior systemic relapse. From a review of previous cases, isolated CNS relapse appears to be more common in patients with embryonal cell histology (alone or mixed with other elements) and occurred after a median of 8.5 months following initial presentation. Long-term survival appears possible using multi-modal treatment with whole-brain radiotherapy, surgery and/or chemotherapy. However, the optimal treatment of isolated CNS relapse remains undefined.

Embryonal carcinoma of the testis associated with prostate cancer in a 72-year-old man

A 72-year-old Japanese man presented with a painless swollen left scrotal mass with elevated levels of serum alpha-fetoprotein and prostate specific antigen. The patient underwent high orchiectomy under diagnosis and a final pathological examination revealed embryonal carcinoma of the left testis. A systematic needle prostate biopsy under guidance of transrectal ultrasound revealed prostate cancer (Gleason score, 8) on the left lobe (T2aN0M0). Systemic chemotherapy was given for retroperitoneal lymph node metastasis of testicular cancer and hormonal therapy (LH-RH analog) was given for prostate cancer. The patient was well with no evidence of metastasis from the testicular cancer or prostate cancer and with no elevation of serum alpha-fetoprotein or prostate specific antigen 26 months after the orchiectomy.

Changes in cellular immunity during chemotherapy for testicular cancer

BACKGROUND

The changes in vivo in immunocyte functions during chemotherapy that is administered in combination with granulocyte colony-stimulating factor (G-CSF) in humans have not been fully investigated. This study was designed to examine neutrophil functions and the activities of natural killer (NK) cells, during the administration of chemotherapy and G-CSF for the treatment of testicular cancer.

METHODS

Seven patients with germ cell tumors at stage IIA, IIB or IIIB, who were treated with bleomycin, etoposide and cisplatin (BEP), were enrolled in the study. Numbers and activities of neutrophils and NK cells were measured at various times during and after the first course of chemotherapy. Neutrophil phagocytosis was quantitated by flow cytometry with fluorescent latex beads. Bactericidal activity was measured in terms of colony-forming units. The activity of NK cells was measured by monitoring the release of 51Cr.

RESULTS

After BEP chemotherapy, CD16+ and CD56+ cell counts, and neutrophil granulocyte counts decreased while there were no significant changes in the number of lymphocytes. Phagocytosis by neutrophils was enhanced after administration of G-CSF. The activity of NK cells was severely impaired after chemotherapy and did not change after administration of G-CSF.

CONCLUSIONS

After BEP chemotherapy for testicular cancer with G-CSF, neutrophil function was not at all inferior to those before treatment. Natural killer cell activity was suppressed by the BEP chemotherapy and did not change after administration of G-CSF.

Loss of CD30 expression in metastatic embryonal carcinoma: the effects of chemotherapy?

AIMS

CD30 has been shown to be consistently strongly expressed in embryonal carcinomas. Our aim was to examine changes in CD30 expression in embryonal carcinomas before and after treatment with chemotherapy.

METHODS AND RESULTS

One hundred and eighteen retroperitoneal lymph node dissections from patients with metastatic germ cell tumours were reviewed. Seventeen contained embryonal carcinoma deposits. In nine cases, the matching pre-chemotherapy orchidectomy specimens were available. The cases were immunohistochemically stained for CD30. All nine pre- chemotherapy orchidectomy specimens showed embryonal carcinoma and stained strongly positively for CD30. However, only four out of nine of the matched post-chemotherapy retroperitoneal lymph node dissection specimens and a total of six out of 17 (35%) with embryonal carcinoma deposits stained for CD30. Ten seminomas were negative for CD30. Loss of CD30 did not appear to influence the relapse rate of the patients.

CONCLUSIONS

Loss of CD30 expression occurs frequently in metastatic embryonal carcinomas after chemotherapy. This finding has implications in the use of CD30 in the diagnosis of metastatic non-seminomatous germ cell tumours and suggests that chemotherapy may alter the immunophenotype of embryonal carcinoma while retaining its characteristic histological appearances.

Curcumin-induced differentiation of mouse embryonal carcinoma PCC4 cells

Curcumin, a natural component of turmeric extracted from the rhizomes of Curcuma longa, is known to exhibit a number of biological properties. In the present study, curcumin, at low concentration, was shown to induce differentiation in embryonal carcinoma cell line PCC4. In response to curcumin, PCC4 cells ceased to proliferate and showed cell cycle arrest at G1 phase after 4 hours of treatment, followed by their differentiation which is characterized by increase of nuclear/cytoplasmic ratio. The expression of hsp 70 was also seen upon 8 h of curcumin treatment, and it remained constant up to 48 h. Differentiated cells also expressed a series of differentiation markers such as lamin A, well-established actin, and keratin cytoskeleton. We used mRNA differential display analysis to identify the genes that are regulated during curcumin-induced differentiation of PCC4 cells. We cloned and sequenced three partial cDNAs that were differentially expressed in normal and differentiated cells. Sequence comparison of one downregulated cDNA (Al) has shown homology to a gene present on mouse chromosome five, while the two upregulated cDNA (C1 and C7) are homologous to several mouse ESTs clones from organs of mesodermal origin. We have identified the full-length coding sequence of the Cl fragment with a putative amino acid sequence. Tissue-specific Northern with RNA from adult mouse organs with the C1 fragment alone showed hybridization with mRNA from several tissues, whereas the same Northern with only the coding sequence showed expression of C1 gene mainly in the adult kidney. Homology search revealed that C1 sequence is part of the 3' UTR and may be common to several genes expressed in many tissues. Thus, curcumin appears to differentiate embryonal carcinoma cell PCC4, and one of the upregulated genes seems to be expressed mainly in the adult kidney.

F9 embryocarcinoma cells: a cell autonomous model to study the functional selectivity of RARs and RXRs in retinoid signaling

Mouse F9 embryocarcinoma (EC) cells constitute a well established cell-autonomous model system for investigating retinoid signaling in vitro as, depending on culture conditions, retinoic acid (RA) can induce their differentiation into either primitive, parietal or visceral extraembryonic endoderm-like cells. These RA-induced differentiations are accompanied by decreases in proliferation rates, modifications of expression of subsets of RA-target genes, and induction of apoptosis. To elucidate the roles played by the multiple retinoid receptors (RARs and RXRs) in response to RA treatments, F9 EC cells lacking one or several RARs or RXRs were engineered through homologous recombination. Mutated RARs and/or RXRs were then reexpressed in given RAR or RXR null backgrounds. WT and mutant cells were also treated with different combinations of ligands selective for RXRs and/or for each of the three RAR isotypes. These studies lead to the conclusion that most RA-induced events (e.g. primitive and visceral differentiation, growth arrest, apoptosis and activation of expression of a number of genes) are transduced by RARgamma/RXRalpha heterodimers, whereas some other events (e.g. parietal differentiation) are mediated by RARalpha/RXRalpha. heterodimers. They also demonstrate that both AF-1 and AF-2 activation functions of RARs and RXRs, as well as their phosphorylation, are differentially required in these RA-induced events. In RARgamma/RXRalpha heterodimers, the phosphorylation of RARgamma is necessary for triggering primitive differentiation, while that of RXRalpha is required for growth arrest. On the other hand, phosphorylation of RARalpha is necessary for parietal differentiation. Thus, retinoid receptors are sophisticated signal integrators that transduce not only the effects of their cognate ligands, but also those of ligands that bind to membrane receptors.

Retinoic acid activates p53 in human embryonal carcinoma through retinoid receptor-dependent stimulation of p53 transactivation function

Although retinoids are known to regulate gene transcription by activating retinoid receptors, the targets of retinoid receptors are largely unknown. This study indicates effective all-trans retinoic acid (RA)-induced differentiation of human embryonal carcinoma cells engages p53. Unexpectedly, RA has been found to activate the transactivation function of p53 in the human embryonal carcinoma cell line, NT2/D1, in a retinoid receptor-dependent manner. A derived RA-resistant line, NT2/D1-R1, is deficient in this activity and is co-resistant to cisplatin. This indicates that RA and cisplatin responses may share a common pathway involving p53 in embryonal carcinomas. RA has no effect on p53 steady-state protein levels in either line. RA enhances endogenous p53 transactivation activity in NT2/D1 but not NT2/D1-R1 cells. In addition, RA induces transactivation activity of a gal4-p53 fusion protein, suggesting that RA activates p53 independent of increasing p53 levels or sequence-specific DNA binding. This activity is absent in retinoic acid receptor gamma (RARgamma)-deficient NT2/D1-R1 cells but can be restored upon co-transfection with specific RARs. Transient transfection of a dominant-negative p53 construct in NT2/D1 cells blocks the RA-mediated transcriptional decline of a differentiation-sensitive reporter plasmid and enhances survival of NT2/D1 cells following cisplatin treatment. Taken together, these findings indicate that RA activates the intrinsic activation function of p53 by a novel mechanism independent of effects on p53 stability or DNA binding and that this activation may be a general mechanism that contributes to RA-mediated G1 arrest.

Altered expression of Ape1/ref-1 in germ cell tumors and overexpression in NT2 cells confers resistance to bleomycin and radiation

The human AP endonuclease (Ape1 or ref-1) DNA base excision repair (BER) enzyme is a multifunctional protein that has an impact on a wide variety of important cellular functions including oxidative signaling, transcription factor regulation, and cell cycle control. It acts on mutagenic AP (baseless) sites in DNA as a critical member of the DNA BER repair pathway. Moreover, Ape1/ref-1 stimulates the DNA-binding activity of transcription factors (Fos-Jun, nuclear factor-kappaB, Myb, ATF/cyclic AMP-responsive element binding protein family, HIF-1alpha, HLF, PAX, and p53) through a redox mechanism and thus represents a novel component of signal transduction processes that regulate eukaryotic gene expression. Ape1/ref-1 has also been shown to be closely linked to apoptosis associated with thioredoxin, and altered levels of Ape1/ref-1 have been found in some cancers. In a pilot study, we have examined Ape1/ref-1 expression by immunohistochemistry in sections of germ cell tumors (GCTs) from 10 patients with testicular cancer of various histologies including seminomas, yolk sac tumors, and malignant teratomas. Ape1/ref-1 was expressed at relatively high levels in the tumor cells of nearly all sections. We hypothesized that elevated expression of Ape1/ref-1 is responsible in part for the resistance to therapeutic agents. To answer this hypothesis, we overexpressed the Ape1/ref-1 cDNA in the GCT cell line NT2/D1 using retroviral gene transduction with the vector LAPESN. Using an oligonucleotide cleavage assay and immunohistochemistry to assess Ape1/ref-1 repair activity and expression, respectively, we found that the repair activity and relative Ape1/ref-1 expression in GCT cell lines are directly related. NT2/D1 cells transduced with Ape1/ref-1 exhibited 2-fold higher AP endonuclease activity in the oligonucleotide cleavage assay, and this was reflected in a 2-3-fold increase in protection against bleomycin. Lesser protection was observed with gamma-irradiation. We conclude that: (a) Ape1/ref-1 is expressed at relatively high levels in some GCTs; (b) elevated expression of Ape1/ref-1 in testicular cancer cell lines results in resistance to certain therapeutic agents; and (c) Ape1/ref-1 expression in GCT cell lines determined by immunohistochemistry and repair activity assays parallels the level of protection from bleomycin. We further hypothesize that elevated Ape1/ref-1 levels observed in human testicular cancer may be related to their relative resistance to therapy and may serve as a diagnostic marker for refractory disease. To our knowledge, this is the first example of overexpressing Ape1/ref-1 in a mammalian system resulting in enhanced protection to DNA-damaging agents.

Prediction of relapse after lymph node dissection for germ cell tumours: can salvage chemotherapy be avoided?

Salvage chemotherapy has been used by some oncology centres for patients with residual malignant or immature elements in retroperitoneal lymph node dissections removed for metastatic non-seminomatous germ cell tumours. However, surveillance of these patients shows that many are cured by surgery alone. 118 retroperitoneal lymph node dissections for metastatic non-seminomatous germ cell tumours were reviewed and the morphology seen within them was quantified. 28 of these had immature or malignant elements and had been treated by surveillance before administration of further chemotherapy. The proliferation rate in these cases was assessed by immunochemistry. The proliferation index and the amount of embryonal carcinoma (EC) were both predictors of recurrence and therefore the need for further chemotherapy. Patients with greater than 25% of EC had an 84% chance of relapse and those with a Ki-67 index of greater than 50% had a 71% chance of relapse. The two tests had a positive predictive value of 83% and 71%, respectively. Patients with such a high risk of recurrence could be considered for post-operative adjuvant therapy at this point whilst others would be suitable for a watchful waiting approach.