Proto-oncogenes and tumor suppressor genes in human urological malignancies

Helminths in human carcinogenesis

This review examines the salient literature on selected helminths involved in carcinogenicity in humans and updates information in an earlier review on cancer and helminths by Mayer and Fried (2007, Advances in Parasitology 65, 239-296). The earlier review was concerned with various helminths, i.e., trematodes, cestodes, and nematodes, that are definitely implicated as being carcinogenic. This review examines only those helminths, all of which turn out to be trematodes, that are definitely implicated as being carcinogenic. These trematodes are the blood flukes Schistosoma haematobium, associated with inducing human carcinoma of the urinary bladder and the liver flukes Opisthorchis viverrini and Clonorchis sinensis, associated with inducing cancer of the bile duct (cholangiocarcinoma) and cancer of the liver (hepatocarcinoma) in humans. The review examines mainly the epidemiology and pathology of these helminthic infections in humans and considers what we know about the mechanisms associated with the carcinogenicity of these three trematodes in humans.

The role of helminth infections in carcinogenesis

This review examines the significant literature on the role of helminth infections in carcinogenesis. Both parasitic infections and cancer have complex natural histories and long latent periods during which numerous exogenous and endogenous factors interact to obfuscate causality. Although only two helminths, Schistosoma haematobium and Opisthorchis viverrini, have been proven to be definitely carcinogenic to humans, others have been implicated in facilitating malignant transformation. The known mechanisms of helminth-induced cancer include chronic inflammation, modulation of the host immune system, inhibition of intracellular communication, disruption of proliferation-antiproliferation pathways, induction of genomic instability and stimulation of malignant stem cell progeny. Approximately 16% of all cancer cases worldwide are attributable to pathogenic agents, including schistosomes and liver flukes. This equates to 1,375,000 preventable cancer deaths per year. Means to reduce the incidence of helminth-associated malignancies are discussed.

Proliferating-cell nuclear antigen (PCNA) as an independent prognostic marker in patients after prostatectomy: a comparison of PCNA and Ki-67

OBJECTIVE

To investigate the prognostic value of prostatic tumour cell proliferation, as measured by Ki-67 and proliferating cell nuclear antigen (PCNA), and to compare these measures in men at low and high risk for progression of tumour.

PATIENTS AND METHODS

Two groups of patients with prostate cancer, i.e. 'metastatic' (M, 22) who had pT3b-4aN0M0 and pTanyN1M0, and 'nonmetastatic' (NM, 18), who had < or =pT3aN0M0 disease, were selected from a well-examined and mapped group of 114 treated by radical prostatectomy. Patients in the NM group were selected by the criteria of having a Gleason score of < or = 7. To assess proliferation, 1000 cells were counted at x 400 magnification by two observers and the percentage of tumour cells positively stained with Ki-67 and PCNA defined as the Ki-67 and PCNA labelling index (LI), respectively. The two LI were compared in the NM and M groups, and the correlation of the LIs with pathological stage, progression and prostate-specific antigen (PSA)-free survival evaluated. Prognostic values of the LI were analysed using multivariate analysis.

RESULTS

The mean (range) follow-up was 33 (4-78) months. The mean LIs were higher in the M than the NM group for both PCNA and Ki-67 (P = 0.02 and 0.019, respectively). Both LIs were markedly different between the groups when stratified by progression, with both significantly higher in men with progression in the NM group. Both LIs had a significant association with Gleason score, pathological stage, progression and PSA-free survival. In multivariate analysis the PCNA LI, surgical margin status and pathological stage were independent factors for progression.

CONCLUSION

Tumour cell proliferation as assessed by Ki-67 or PCNA correlate significantly with progression. The PCNA LI was an independent predictor of progression, especially in patients with a low risk of progression according to predefined criteria.

Tyrosine-317 of p52(Shc) mediates androgen-stimulated proliferation signals in human prostate cancer cells

The involvement of tyrosine phosphorylation signaling pathways in steroid-induced cell proliferation has received much attention. However, the adaptor molecule that mediates this interaction remains to be identified. In this communication, we identify p52(Shc) as the mediator between tyrosine phosphorylation signaling and steroid signaling in steroid-responsive cell proliferation. Although the different LNCaP prostate cancer cells, C-33, C-51 and C-81, express similar levels of functional androgen receptor (AR), they exhibit different levels of androgen sensitivity. C-33 cell proliferation is highly responsive to the presence of androgens, whereas C-51 cell proliferation is comparatively less responsive to androgens. In contrast, C-81 cell proliferation is independent of androgens. In these cells, tyrosine phosphorylation levels of both p52(Shc) and ErbB-2 were greatest in C-81 cells, comparatively less in C-51 cells and weaker in C-33 cells. The levels and activity of protein tyrosine phosphatase, cellular prostatic acid phosphatase, decreased correspondingly in those cells. In both androgen-independent, rapidly growing C-81 and ErbB-2 cDNA-transfected C-33 cells, p52(Shc) was hyperphosphorylated at Tyr317 (Y317). Conversely, p52(Shc) tyrophosphorylation was decreased in prostatic acid phosphatase cDNA-transfected stable subclones of C-81 cells, which restore androgen-sensitive proliferation and leads to slow growth rates. In C-33 cells, androgen-stimulated cell proliferation correlated with tyrophosphorylation of ErbB-2 and increased phosphorylation of p52(Shc) at Y317, but not at Y239, differing from phosphorylation patterns associated with epidermal growth factor (EGF) stimulation. Furthermore, overexpression of a mutant of p52(Shc), that is Y317F, blocks Y317 phosphorylation of endogenous p52(Shc) and abolishes androgen-stimulated proliferation, but not EGF-stimulated proliferation. Thus, Y317 of p52(Shc) serves as an important regulatory site that allows tyrosine phosphorylation pathways to moderate androgen sensitivity in human prostate cancer cells.

Cytotoxicity of human prostate cancer cell lines in vitro and induction of apoptosis using 213Bi-Herceptin α-conjugate

HER-2 has been implicated in the oncogenesis of human prostate cancer (CaP) and is the target of a new treatment for metastatic breast cancer using the humanised monoclonal antibody (MAb) trastuzumab (Herceptin). In this study, a novel alpha-particle emitting [213Bi]Herceptin construct, which targets the HER-2 extracellular domain on CaP cells, was prepared and evaluated in vitro. We used immunocytochemistry, flow cytometry and Western blot analysis to examine the expression of HER-2 in a panel of established human CaP cell lines, used the MTS assay to evaluate the cytotoxicity of 213Bi-Herceptin on these cell lines and the TUNEL assay to document apoptosis. The results indicate that LNCaP-LN3 cells express high levels of HER-2 protein, in contrast, DU 145 cells express low to medium levels, and PC-3 cells express an undetectable level of HER-2 protein. 213Bi-Herceptin was specifically cytotoxic to LNCaP-LN3 cells in a concentration-dependent fashion, cause the cells to undergo apoptosis, whereas DU 145 showed an HER-2 level-dependent response to 213Bi-Herceptin cytotoxicity. In contrast, PC-3 cells were resistant to 213Bi-Herceptin-induced cytotoxicity. The 213Bi-Herceptin induced apoptosis in LNCaP-LN3 cells could be inhibited by incubation with unlabeled Herceptin. Our results suggest that 213Bi-Herceptin alpha-conjugate might be a promising new agent for the treatment of preangiogenic cancer cell clusters or micro-metastases with high levels of HER-2 expression.

Pilot attempt of advanced prostate cancer treatment T3NxMx?1 by intermittent more complete androgen blockade

The aim of the prospective pilot study was evaluating efficacy and tolerance of pharma-cological more complete androgen blockade (mMAB) by using Zoladex LA 10.8 mg, Casodex 50 mg and Proscar 5 mg in patients with advanced prostate cancer (T3,Nx Mx-1).

METHODS

This five-year study involved 14 patients aged 67-82 years (average 73). Zoladex LA was administered subcutaneously every 3rd month of treatment, and every day 1 tablet Casodex and 1 tablet Proscar. In the time when PSA was <0.1 mg/ml Zoladex and Casodex were withdrawn, and only Proscar was left. The mMAB treatment was resumed when PSA > 0.1 ng/ml. Before and every 3 months the following laboratory tests were made: PSA, sedimentation, bilirubine, transaminase, phosphatase, ultrasonography (USG); and adverse events were registered. The following criteria of assessment were adopted: CR--complete response--examination tests normal, improved condition, reduction of prostate dimension in USG and value of PSA < 0.1 ng/ml; PR partial response i.e. no progression, the PSA level drops down to the reference values and a reduction of prostate dimension in USG occurs, NR--no response i.e. progression, increased prostate dimension in USG and/or metastases in scintygraphy, as well as PSA above normal.

RESULTS

The mean followup time was 60 months. After the initial 6 months two patients were off-therapy mMAB because they were qualified for radiotherapy. A successive patient (no. 5) was off-therapy (after 4 years) because he left Warsaw to go abroad. After 60 months results mMAB were based on 11 patients' records, and a complete response was confirmed in 7 patients, partial response in 3 patients and no response in one patient.

CONCLUSION

Results of this study show that pharmacological intermittent mMAB is an efficient way of treating advanced prostate cancer. Side effects are low and occur in moderate intensity and do not oblige to treatment withdrawal.

Suppression of LNCaP prostate cancer xenograft tumors by a prostate-specific protein tyrosine phosphatase, prostatic acid phosphatase

BACKGROUND

Although the molecular mechanism of androgen-independent prostate cancer growth and progression has been gradually elucidated, there is limited effective treatment for this prevalent disease. Human prostatic acid phosphatase (PAcP), a major protein tyrosine phosphatase in prostate epithelium, plays a critical role in regulating the growth of prostate cancer cells. In prostate carcinomas, the expression of cellular PAcP decreases. To explore directly the possible therapeutic potential of cellular PAcP, we investigated the suppression effect of PAcP by utilizing cDNA direct intratumoral administration in androgen-independent LNCaP xenograft tumors.

METHODS

An androgen-independent LNCaP cell model (C-33 and C-81 cells) and stable subclones of PAcP cDNA-transfected C-81 cells (LNCaP-23 and LNCaP-34 cells) were used for the experiments. We examined the growth property and expression of PAcP and c-ErbB-2 of these different LNCaP cells in vitro and in vivo. We subsequently investigated the growth suppression effect of PAcP cDNA intratumoral injection in pre-established C-81 xenograft tumors, and analyzed the expression of PAcP, prostate-specific antigen (PSA), proliferating cell nuclear antigen (PCNA), and c-ErbB-2 in the tumors by immunohistochemistry and Western blotting.

RESULTS

The different LNCaP cells exhibited different growth property and tumorigenicity, both in cell culture and xenograft. Biochemical characterizations revealed that the level of cellular PAcP correlated negatively with the growth property of different LNCaP cells, while the level of tyrophosphorylated c-ErbB-2 had an inverse correlation with cellular PAcP. The single intratumoral administration of the wild type PAcP cDNA showed a significant suppression effect on C-81 xenograft tumor growth, compared to vector alone-injected control (P<0.05). In the tumors injected with this PAcP cDNA, the PAcP expression was detected 1 week (wk) after injection, but was undetectable at 6 wk, which inversely correlated with the level of tyrophosphorylated c-ErbB-2 and the degree of cell proliferation indicated by PCNA staining.

CONCLUSIONS

Our results clearly demonstrated that cellular PAcP has a suppression effect on the growth of androgen-independent LNCaP xenograft tumors. This effect occurs at least partly through the dephosphorylation of c-ErbB-2 by PAcP, the prostate-specific protein tyrosine phosphatase. The data indicates that human PAcP could be utilized in the corrective gene therapy for a subgroup of androgen-independent human prostate cancer cells that lack cellular PAcP expression.

Establishment and characterization of androgen-independent human prostate cancer LNCaP cell model

BACKGROUND

The acquisition of an androgen-independent phenotype is the most serious issue of prostate cancer treatment. Although several experimental cell models have been reported for studying androgen independence, they have limited applications related to hormone-refractory prostate cancer. To investigate the molecular mechanism of androgen-independent growth of prostate cancer, we established a useful LNCaP cell model that resembles the clinical scenario of hormone-refractory prostate cancer.

METHODS

Androgen-sensitive LNCaP parental cells were continuously maintained in a regular cell-culture medium, that is, phenol red-positive RPMI 1640 medium supplemented with 5% fetal bovine serum and 1% glutamine. Upon passage, the androgen responsiveness of those cells decreased, to a level lower than that of parental cells. We examined the growth properties and androgen responsiveness of these different LNCaP cells in vitro and in vivo. Cytogenetic characteristics and expression of androgen receptors (ARs) and prostate-specific antigen (PSA) were determined.

RESULTS

Upon continuous passage, the biological behavior of parental C-33 cells (passage number less than 33) was altered. C-81 cells (passage number higher than 81) clearly exhibited more aggressive growth and lower androgen responsiveness than C-33 and C-51 cells (passage number between 35 and 80) in vitro and in vivo. Nevertheless, all these cells expressed a similar level of functional AR protein as well as a similar genetic profile. Moreover, in a steroid-reduced culture condition, C-81 cells secreted a higher level of PSA than C-33 cells.

CONCLUSIONS

Our LNCaP cell model closely recapitulates the progression of human prostate cancer from the androgen-responsive to the hormone-refractory state under the androgen nondeprived condition. This cell model may provide the opportunity to understand the molecular mechanisms associated with the acquisition of androgen independence during human prostate cancer progression.

Expression of CD44 protein in renal cell carcinomas: association with p53 expression

CD44 is an adhesion molecule involved in cell-to-cell and cell-to-matrix interactions. Recent evidence indicates a role of CD44 in tumor growth and metastatic potential of tumor cells. Moreover, it is widely known that the p53 tumor suppressor gene controls cell proliferation and loss of its normal function may lead to carcinogenesis. To investigate the role of these biomarkers in renal cancer, we analyzed the immunohistochemical distribution of CD44's expression on formalin fixed paraffin embedded tissue from 67 renal cell carcinomas and correlated with clinicopathologic parameters as well as with p53 suppressor gene expression. The monoclonal antibodies CD44 and p53 were applied to the tissues using the streptavidin biotin peroxidase method after microwave antigen retrieval. For CD44 and p53 more than 10% membranous and 5% nuclear staining, respectively, were estimated as positive. CD44's membranous immunoreactivity was detected in 24/67 tumors (35%) and mostly in carcinomas of clear/granular cell type. Nine tumors expressed nuclear immunoexpression of p53 protein (13.4%). Statistically significant correlation was noted between CD44 expression and nuclear grade (P < 0.001), tumor stage (P < 0.001), vascular invasion (P < 0.05) and p53 expression (P < 0.01). These results suggest that CD44s and p53 are markers of tumor progression in renal cell cancer.

Identification of a novel gene on chromosome 13 between BRCA-2 and RB-1

METHODS AND RESULTS

By differential display we isolated a new cDNA-fragment, named C13, that is downregulated in malignant prostate tissues. Northern hybridization revealed the fragment to be part of 3.0 and 4.4 kb mRNAs. Fluorescence in situ hybridization, Southern blotting and radiation hybrid mapping demonstrated a chromosomal localization of C13 on 13q12-14 closest to the SHGC-34125 marker. In the 5% chromosomal environment of C13 we detected changes of the allelic status in 13 of 21 prostate cancers. A downregulation was detected at the mRNA level in patients with advanced carcinoma. The 3.0 kb full length cDNA clone encodes a protein with an open reading frame of 2,202 bp or 733 amino acids. The corresponding protein contains a putative nuclear localization signal, several glutamine clusters and an alpha-helix-rich domain. By in situ RNA hybridization we could demonstrate the mainly epithelial expression of the C13 mRNA in prostatic tissue.

CONCLUSIONS

The localization of C13 between the tumor suppressor genes BRCA-2 and RB-1, the detected allelic imbalances, the downregulation of its mRNA in some prostatic cancer tissues, the epithelial expression and the described protein structure suggest that this gene encodes a protein that may have tumor or metastasis suppressing function in prostate tissue.

Synchronous appearance of germ cell tumor and papillary carcinoma of the thyroid

Synchronous appearance of 2 different malignancies in one patient is a rare phenomenon. We describe our experience of 2 patients with synchronous malignancies of the testis and thyroid gland, and of a third patient who developed a thyroid neoplasm unrelated to recent treatment for a germ cell tumor. The medical records of 3 male patients treated for both a germ cell tumor and a thyroid cancer between 1989 and 1994 were reviewed. Two patients with nonseminomatous germ cell tumor received postoperative chemotherapy after orchiectomy and developed a papillary carcinoma of the thyroid during treatment. A third patient, who received radiation therapy for a clinical stage 1 seminoma, recurred with biopsy proven seminoma in the neck in association with a thyroid nodule 2 years later. All 3 patients had their thyroid cancer treated by surgical resection, and one received adjuvant radioactive iodine. Two of the patients are currently alive and disease-free. One patient died of pulmonary complications that stemmed from bleomycin toxicity. Synchronous appearance of germ cell tumor and papillary carcinoma of the thyroid has not been previously described. Genetic predisposition may play a role in the development of such simultaneous neoplasms.

Interaction between protein tyrosine phosphatase and protein tyrosine kinase is involved in androgen-promoted growth of human prostate cancer cells

Steroid hormones play key roles in regulating cell proliferation and differentiation in targeting tissues. However, in advanced cancers, the steroid hormone regulation is frequently attenuated through a yet unknown mechanism even in the presence of functional steroid hormone receptors. We investigate the functional role of tyrosine phosphorylation signaling in the hormone-refractory growth of human prostate tumors. Initial studies demonstrate that the androgen-responsive phenotype of human prostate cancer cells associates with a low phosphotyrosine (p-Tyr) level of ErbB-2, which is regulated by cellular prostatic acid phosphatase (PAcP), a protein tyrosine phosphatase. In prostate cancer cells, the p-Tyr level, but not the protein level, of ErbB-2 inversely correlates with the androgen-responsiveness of cell proliferation. Androgen-stimulated cell growth concurs with a down-regulation of cellular PAcP, an elevated p-Tyr level of ErbB-2, and the activation of mitogen-activated protein kinases. Furthermore, only the ErbB-2 inhibitor AG 879, but not the EGFR inhibitor AG 1478, abolishes androgen-induced cell proliferation. Forced expression of ErbB-2 can also attenuate androgen promotion of cell growth. Data taken collectively conclude that in human prostate cancer cells, the tyrosine phosphorylation of ErbB-2 regulated by cellular PAcP plays a key role in regulating androgen-mediated proliferation signaling. Oncogene (2000).

Prognostic value of immunohistochemical expression of the c-erbB-2 oncoprotein in metastasic prostate cancer

It is well established that the activation of proto-oncogenes could trigger uncontrolled cell growth and cancer development. Although this correlation has already been evidenced in several human tumors, no conclusive studies have related oncogene activation with the development of prostatic neoplasia. Nevertheless, some reports suggest that c-erbB-2, which is a prognostic marker in breast cancer, could be implicated in the development of prostatic adenocarcinoma. We have studied the expression of the c-erbB-2 oncoprotein in primary prostatic tissue in a series of 70 patients with metastasic disease, by means of immunohistochemistry. The NCL-B 11 anti-c-erbB-2 monoclonal antibody was used, and the immunoreactivity was quantified by image analysis. The overall rate of prostatic-tissue sections presenting positive c-erbB-2 immunostaining was 64.3%. No significant relation was observed between histological grade and c-erbB-2 over-expression or severity of the disease, based on the extent of metastases. The average specific survival in patients with c-erbB-2 over-expression was 33 months, while it was 54 in patients with c-erbB-2 negativity; p < 0. 034. These results, as well as the logistic-regression analysis, suggest that expression of c-erbB-2 oncoprotein would be considered as an independent prognostic factor of metastatic prostate cancer. Moreover, it could discriminate between the prognosis of patients with Gleason score 2 to 7 and those with score 8 to 10. Our results suggest that the expression of c-erbB-2 oncoprotein in primary prostatic tissue could have a prognostic value in patients with metastatic prostate cancer. Int. J. Cancer (Pred. Oncol.) 84:421-425, 1999.

Activation of Rb and decline in androgen receptor protein precede retinoic acid-induced apoptosis in androgen-dependent LNCaP cells and their androgen-independent derivative

Androgen ablation-induced prostate cancer regression is transient and ends with the regrowth of androgen-independent (AI) tumors. To mimic this evolution in culture, we chronically deprived an androgen-dependent (AD) prostate cancer cell line (LNCaP) of androgen, generating an AI derivative which retained limited hormone proliferative responsiveness and a barely detectable prostate-specific antigen (PSA) mRNA level. While the cytokeratin 8 (CK8) level was low, the androgen receptor (AR) protein in AI cells was on average tenfold greater than in AD cells. When challenged for susceptibility to undergo apoptosis, the AI cells were more resistant than AD cells to all-trans retinoic acid (tRA) and two chemotherapeutic agents, Taxol and Adriamycin, requiring higher doses and longer periods of treatment to achieve similar effects. Compared to AD cells, the partially apoptosis-resistant AI cells expressed four times more Bcl-2 protein and undetectable levels of p21/WAF1. Induction of apoptosis by tRA in both cell types did not affect their expression but was preceded by the activation of Rb and a pronounced reduction of AR protein level. The kinetics of the Rb activation and AR downmodulation in both cell types matched their tRA sensitivity, suggesting that these events may be required for tRA-induced apoptosis. The results show that the apoptotic pathway in AI cells, although more difficult to induce, is not irrevocably lost and that targeted reduction of the AR protein level with retinoids in combination with androgen ablation therapy may prolong remissions in advanced prostate cancer patients.

Mechanisms of apoptosis by c-Myc

Much recent research on c-Myc has focused on how it drives apoptosis. c-Myc is widely known as a crucial regulator of cell proliferation in normal and neoplastic cells, but until relatively recently its apoptotic properties, which appear to be intrinsic, were not fully appreciated. Its death-dealing aspects have gained wide attention in part because of their potential therapeutic utility in advanced malignancy, where c-Myc is frequently deregulated and where novel modalities are badly needed. Although its exact function remains obscure, c-Myc is a transcription factor and advances have been made in characterizing target genes which may mediate its apoptotic properties. Candidate regulators and effectors are also emerging. Among recent findings are connections to the CD95/Fas and TNF pathways and roles for the tumor suppressor p19ARF and the c-Myc-interacting adaptor protein Binl in mediating cell death. In this review I summarize the data establishing a role for c-Myc in apoptosis in diverse settings and present a modified dual signal model for c-Myc function. It is proposed that c-Myc induces apoptosis through separate 'death priming' and 'death triggering' mechanisms in which 'death priming' and mitogenic signals are coordinated. Investigation of the mechanisms that underlie the triggering steps may offer new therapeutic opportunities.

Relationship between schistosomiasis and bladder cancer

Carcinoma of the urinary bladder is the most common malignancy in the Middle East and parts of Africa where schistosomiasis is a widespread problem. Much evidence supports the association between schistosomiasis and bladder cancer: this includes the geographical correlation between the two conditions, the distinctive patterns of gender and age at diagnosis, the clinicopathological identity of schistosome-associated bladder cancer, and extensive evidence in experimentally infected animals. Multiple factors have been suggested as causative agents in schistosome-associated bladder carcinogenesis. Of these, N-nitroso compounds appear to be of particular importance since they were found at high levels in the urine of patients with schistosomiasis-associated bladder cancer. Various strains of bacteria that can mediate nitrosation reactions leading to the formation of N-nitrosamines have been identified in the urine of subjects with schistosomiasis at higher intensities of infection than in normal subjects. In experimental schistosomiasis, the activities of carcinogen-metabolizing enzymes are increased soon after infection but are reduced again during the later chronic stages of the disease. Not only could this prolong the period of exposure to activated N-nitrosamines, but also inflammatory cells, stimulated as a result of the infection, may induce the endogenous synthesis of N-nitrosamines as well as generating oxygen radicals. Higher than normal levels of host cell DNA damage are therefore anticipated, and they have indeed been observed in the case of alkylation damage, together with an inefficiency in the capacity of relevant enzymes to repair this damaged DNA. In experimental schistosomiasis, it was also found that endogenous levels of host cell DNA damage were related to the intensity of infection. All of these factors could contribute to an increased risk of bladder cancer in patients with schistosomiasis, and in particular, the gene changes observed may have potential for use as biomarkers in the early detection of bladder cancer that may assist in alleviating the problem.

Prognostic markers in bladder cancer: a contemporary review of the literature

PURPOSE

We provide a contemporary review of bladder tumor markers and summarize their role as prognostic indicators.

MATERIALS AND METHODS

A comprehensive review of the literature on prognostic markers for transitional cell carcinoma of the bladder was performed.

RESULTS

Intense research efforts are being made to identify and characterize better various bladder cancers and their true biological potential. The need to predict which superficial tumors will recur or progress and which invasive tumors will metastasize has led to the identification of a variety of potential prognostic markers. Blood group antigens, tumor associated antigens, proliferating antigens, oncogenes, peptide growth factors and their receptors, cell adhesion molecules, tumor angiogenesis and angiogenesis inhibitors, and cell cycle regulatory proteins have recently been identified. The potential clinical applications of these tumor markers are under active investigation. Recent attention has focused on which tumor markers may predict the responsiveness of a particular bladder cancer to systemic chemotherapy.

CONCLUSIONS

At present conventional histopathological evaluation of bladder cancer (tumor grade and stage) cannot predict accurately the behavior of most bladder tumors. With a better understanding of the cell cycle, and cell to cell and cell to extracellular matrix interactions as well as improved diagnostic techniques (immunohistochemistry), progress is being made to identify and characterize other potential prognostic markers for transitional cell carcinoma of the bladder. The ultimate goal is to develop reliable prognostic markers that will accurately predict not only the course but also the response of a tumor to therapy. This information may then be used to dictate more aggressive treatment for tumors that are likely to progress and less aggressive treatment for those that are unlikely to progress. In the future these biological markers may also be used in gene therapy for the treatment of bladder cancer.

Gene therapy for prostate cancer

Prostate cancer remains one of the most significant challenges in clinical oncology, yet present therapies provide incomplete treatment in many cases. Innovative and practical gene therapy-based approaches will prove invaluable in filling the gaps that now exist in the treatment of localized and distant disease. Although multiple potential strategies have been developed, early clinical trials in prostate cancer gene therapy are now in the phase I/II stage of development. Novel preclinical and early clinical data should be considered optimistically, yet cautiously, as this field emerges from its infancy.

An evaluation of the markers p53 and Ki-67 for their predictive value in prostate cancer

BACKGROUND AND OBJECTIVES

p53 and Ki-67 are but two markers being evaluated for their predictive value in prostate cancer. The purpose of this study was to compare p53 and Ki-67 with age, stage, Gleason score, and ploidy for their prognostic abilities in prostate cancer.

METHODS

Prostate cancer specimens from 134 patients were immunohistochemically stained for p53 and Ki-67 expression and differences evaluated by SPSS analysis of variance (ANOVA) methods. The dependent variable was patient survival and the independent variables were age, stage, Gleason score, and ploidy.

RESULTS

In decreasing order of prediction of survival were stage (P < 0.001), Gleason score (P < 0.001), age (P = 0.1869), Ki-67 (P = 0.2284), p53 (P = 0.4282) and ploidy (P = 0.8141).

CONCLUSION

It is concluded that stage and Gleason score are significant predictors of survival while p53, Ki-67, age and ploidy are not.

Nuclear p53 overexpression in bladder, prostate, and renal carcinomas

BACKGROUND

The aim of this study was to examine nuclear p53 overexpression in transitional cell carcinoma of the bladder, adenocarcinoma of the prostate, and renal cell carcinoma.

METHODS

Forty-four pathologic specimens from 39 bladder cancer patients, 41 prostatic adenocarcinoma, and 39 renal cell carcinoma specimens were analyzed immunohistochemically with D07 monoclonal antibody to detect the expression of the mutant p53 gene. Overexpression was said to occur when the number of positively-stained tumor nuclei were > or = 10% in each specimen. p53 overexpression was correlated with the clinical and histopathological features of these cancers.

RESULTS

Nuclear p53 overexpression occurred in 18.2% of transitional cell bladder cancer specimens, 12.2% of prostate cancer specimens, and 17.9% of renal cell cancer specimens. Statistical analyses showed that grade, vascular invasion, and necrosis in bladder cancer, a high Gleason score in prostate cancer, and the 1-year mortality rate in renal cancer were significantly related with p53 nuclear overexpression (P < 0.05).

CONCLUSION

Using the D07 monoclonal antibody, nuclear p53 overexpression is relatively uncommon in urologic malignancies, and moderately correlates with several histopathological and clinical features of urologic malignancies.

Alterations of the metastasis suppressor gene nm23 and the proto-oncogene c-myc in human testicular germ cell tumors

The putative metastasis suppressor genes nm23-H1, nm23-H2 and the c-myc proto-oncogene were investigated in testicular germ cell tumors (GCTs) using Southern and Northern blotting as well as semiquantitative reverse transcription polymerase chain reaction (RT-PCR) and single strand conformation polymorphism (SSCP) analysis. When studying Bgl II RFLPs, allelic losses of the nm23 gene were found in 3/12 (25%) informative tumors, and all 3 had lymph node and/or distant metastases. A 2 to 7 fold nm23 mRNA overexpression was found in 22/34 (64.7%) tumors examined. RT-PCR revealed that this phenomenon is mainly a consequence of nm23-H2 overexpression. Overexpression of both the H1 and the H2 gene was predominantly found in the seminoma subtype and was not associated with tumor stage. Only 1/25 tumors, a seminoma with distant metastases, had a point mutation in the coding region of the nm23-H2 gene as demonstrated by SSCP analysis. None of the 8 seminomas and only 1/13 non-seminomas had c-myc overexpression. No abnormalities of the c-myc gene could be detected on the DNA level. Despite the fact that in previous investigations nm23-H2 was demonstrated to be a putative transcription factor for c-myc, no coexpression of c-myc and nm23-H2 was found by quantitative RT-PCR in this study.

Loss of heterozygosity of the nm23-H1 gene in human renal cell carcinomas

This study evaluates the potential contribution of the nm23-H1 gene to malignant transformation in patients with renal cell carcinoma. Using specific oligonucleotide primers for the nm23-H1 microsatellite repetitive sequence, gene instability was followed by polymerase chain reaction/loss of heterozygosity assay on 54 tumor specimens and the corresponding normal tissue samples. We also determined, immunohistochemically, the relative concentration and localization of the nm23-H1 protein product. From 77.7% informative cases, DNA from 6 tumors exhibited loss of heterozygosity, regardless of the tumor stage (TNM). Out of 39 samples analyzed, 30 were negative for Nm23-H1 protein, while the others were only slightly positive. No correlation with tumor stage was found. Normal renal tissue was also negative for this protein. Our results provide the evidence for loss of heterozygosity, followed by means of microsatellite tandem-repeat polymorphism, at the nm23-H1 locus in renal cell carcinoma. However, since no correlation was found between the tumor stage or metastatic potential on the one hand, and allelic loss and specific protein expression on the other, it seems that nm23-H1 does not play a key role in the invasiveness of this tumor type.

Expression of p21 and mutant p53 gene products in residual prostatic tumor cells after radical radiotherapy

BACKGROUND

In a previous study, sextant core biopsies revealed residual tumor in the prostate in 37/55 investigated patients, with an average of 6.8 years after external beam radiation therapy (RRT). More than half of the biopsies exhibited Ki-67 and PCNA proliferation activity.

METHODS

The present study aims at further characterizing residual tumor cells post-RRT by investigating whether the tumor cells exhibit immunohistochemical expression of p21 and mutant p53 gene products, which reflect the state of cell cycle regulatory mechanisms.

RESULTS

Positive p53 staining was observed in 11% and p21 positivity in 47% of biopsies. The proportion of positively stained cells was low for both antigens. The staining patterns point to the existence of wild-type p53-dependent, as well as alternative pathways for p21 protein induction.

CONCLUSIONS

A low proportion of tumor cells exhibited p53 protein accumulation post-RRT. G1 arrest, as assessed by p21 immunoexpression, was demonstrated in a low percentage of tumor cells in < 50% of post-RRT biopsies, indicating that the vast majority of residual tumor cells following RRT escape the G1/S checkpoint control and propagate into S-phase, presumably with a maintained malignant potential.

Biological prognostic factors in renal cell carcinoma

– The authors have reviewed literature regarding the main contributions of molecular biology to renal cell carcinoma characterisation. The progress made in the analysis of chromosomal alterations, oncogenes, p53 protein, proliferation indices and adhesion molecules are described. The authors conclude that molecular biology, especially the analysis of chromosomal alterations and proliferation indices, may contribute to renal cell carcinoma diagnosis and to the understanding of its pathogenesis and prognosis.

Oncoproteins and tumor suppressor proteins in congenital sacrococcygeal teratomas

Congenital sacrococcygeal teratoma (SCT) is the most common germ cell tumor of infancy and childhood with a female preponderance. Most SCTs are diagnosed at birth, are benign, and consist of fully differentiated, mature tissues. Tumorigenesis of SCTs remains poorly understood. Almost nothing is known about possible oncogene activation or tumor suppressor inactivation in these rare tumors. We describe the presence of various oncoproteins and tumor suppressor proteins in eight cases of congenital SCT. The following oncogenes were examined: ras family (c-H-, c-N-, and c-K-ras), early genes (fos, jun), and tumor suppressor genes (p53 and nm23-H-I). There was no relationship between the intensity of expression of these oncoproteins and tumor suppressor genes and the following parameters: tumor size, age, and survival of the patients. We did not observe any difference, however, between the expression of the examined oncogenes and tumor suppressor genes nm23 and p53 in immature and mature teratomas. Our findings suggest that the ras family of oncogenes, fos and jun oncogenes, and nm23 and p53 tumor suppressor genes are present in congenital SCT, indicating a possible role in genesis and development of these tumors.

Molecular and genetic events in schistosomiasis-associated human bladder cancer: role of oncogenes and tumor suppressor genes

Carcinoma of the urinary bladder is the most common malignancy in many tropical and subtropical countries and is mainly due to endemic schistosomal infection. Schistosomiasis-associated bladder cancer defines a characteristic pathology and cellular and molecular biology that differs from urothelial carcinoma of non-schistosomal origin. N-Nitroso compounds are suspected etiologic agents in the process of bladder cancer induction during schistosomiasis. Elevated levels of DNA alkylation damage have been detected in schistosome-infected bladders and are accompanied by an inefficient capacity of DNA repair mechanisms. Consequently, high frequency of G --> A transition mutations were observed in the H-ras gene and at the CpG sequences of the p53 tumor suppressor gene. Genetic changes have also been detected in the c-erbB-1 and c-erbB-2 oncogenes and in the cdkn2 and Rb tumor suppressor genes. The potential application of these mutational patterns in providing a biological marker suitable for the biomonitoring and early detection of this neoplasm could indicate new avenues of approach that might alleviate the problem in the future. It can also assist in elucidating the mechanisms by which schistosomiasis augments human bladder cancers.

Renal medullary carcinoma: clinical and therapeutic aspects of a newly described tumor

BACKGROUND

Renal medullary carcinoma is a newly described, aggressive kidney tumor. All patients with the disease have been African-American with sickle cell (SC) trait or hemoglobin SC disease.

METHODS

Patient information was obtained from individual patient records and from the Department of Defense national data bank, The Defense Enrollment and Eligibility Reporting System. Data were obtained from either personal review of the patient's records or from discussion with the patient's physician. Cytogenetic studies were performed on one patient.

RESULTS

Six patients are presented. All had SC trait. Median age was 24.5 years and 1 patient was female. Time from diagnosis to death averaged 3 months (range 1-7 mos). No objective responses were reported to a wide variety of chemo and immunotherapies: cyclophosphamide, doxorubicin, cisplatin; methotrexate, vinblastine, doxorubicin, and cisplatin; single agent interferon; single agent paclitaxel; or single agent vinblastine. Investigational regimens included topotecan, doxorubicin, and filgrastim; alpha-interferon, interleukin-2, and 5-fluorouracil; and single agent paclitaxel. Cytogenetic studies revealed numerous structural, as well as numerical anomalies. Of the cells successfully karyotyped (n=4), 2 contained abnormalities of chromosome 3 and all contained monosomy 11.

CONCLUSIONS

Renal medullary carcinoma is an aggressive, chemoresistant tumor. Time from discovery of tumor to patient death is very short and has been altered by a wide variety of chemotherapies and immunotherapies. An unidentified genetic component is likely present.

Expression of stem-cell factor and its receptor c-kit protein in normal testicular tissue and malignant germ-cell tumours

The proto-oncogene c-kit and its ligand stem-cell factor (SCF) may play an important role in the development of normal and malignant testicular tissue. This study investigates the presence of SCF and c-kit protein in 32 orchiectomy specimens of patients with testicular cancer, in 5 specimens of normal testicular tissue and in three established non-seminomatous germ-cell cancer cell lines (H12.1, H32, 577ML) by an immunohistochemical approach. Out of 9 testicular cancer specimens classified as pure seminomas, 7 (78%) showed a strong immunohistochemical reaction for both SCF and c-kit protein on the surface of the tumour cells. Fourteen non-seminomatous germ-cell tumours composed of embryonal carcinoma were completely negative for both SCF and c-kit proteins and only faint positivity was found in 6 tumours (26%). Differentiated teratomatous structures within the specimens on non-seminomatous tumours showed a strong immunohistochemical reaction for SCF and c-kit protein in 8 of 11 (73%) cases. All three testicular cancer cell lines showed only faint staining reactions for c-kit protein and none for SCF. No secretion of SCF by the three lines in vitro was detected. The addition of high concentrations of SCF (100 ng/ml) to the testicular cancer cell lines in culture conditions without fetal calf serum resulted in a 1.4 to 3-fold growth stimulation compared to cell growth in serum-free medium alone. This effect was not detectable when the cells were cultured in serum-containing media. In the normal testicular tissue the germ-cells displayed a strong immunohistochemical reaction for c-kit protein while SCF positivity was found at the tubular membrane and on the surface of Sertoli cells. The SCF/c-kit system may possess a regulatory function in normal testicular tissue by possibly providing the microenvironment necessary for spermatogenesis. With the development of testicular cancer, this regulatory system seems to be lost, particularly in non-seminomatous germ-cell tumours. A growth-stimulatory effect of high concentrations of SCF on non-seminomatous testicular cancer cell lines can be detected only in culture conditions with serum-free media. The effects achievable by the combination of SCF with other growth factors need to be further studied, as well as the role of the c-kit/SCF regulatory system for normal spermatogenesis and its possible implications for the understanding and treatment of male infertility.

Differentiation-stage specific expression of oncoprotein 18 in human and rat prostatic adenocarcinoma

Oncoprotein 18 (Op18) is an intracellular phosphoprotein that has been shown to be overexpression in a number of human malignancies. In the present report we have studied the pattern of Op18 expression on normal, hyperplastic, and malignant prostatic tissue as well as in rat prostatic tumor lines. One of the objectives of the present work was to establish whether the level of Op18 expression can be used as a prognostic marker in human prostatic adenocarcinoma. To that end, sections from normal, hyperplastic, and malignant human prostatic tissue were examined by immunohistochemistry for expression of Op18. In the normal and hyperplastic prostate, Op18 expression was observed in basal glandular epithelial cells, whereas the columnar luminal epithelial cells were not stained by the anti Op18 antibodies. In highly differentiated prostatic cancers occasional epithelial cells were stained, while in poorly differentiated tumors most of the epithelial cells contained Op18 immunoreactivity. The staining pattern was similar in the primary prostatic tumor and in the regional lymph node metastases. Most importantly, a limited survey of prostatic cancer patient samples (n = 40) showed a significant correlation between the fraction of Op18 immunoreactive cells and survival. Studies of a rat prostatic tumor model, showed that only a few cells were stained in the highly differentiated Dunning R3327PAP tumor, while most cells were stained in the anaplastic AT1 rat prostatic tumor. Interestingly, castration of rats resulted in an increased Op18 immunoreactivity, within 14 days, in the highly differentiated rat R3327PAP prostatic tumor. In conclusion, the level of Op18 expression seems to be related to cellular differentiation, histological grade, and survival in prostatic cancers. These findings show that Op18 immunoreactivity may be useful as a prognostic marker in prostatic cancer. In addition it may help in the differentiation between highly differentiated prostatic tumors and non-malignant conditions.