Screening of H-ras gene point mutations in 50 cases of bladder carcinoma

Mutational Analysis of the BRAF Gene in Transitional Cell Carcinoma of the Bladder

Purpose

Mutational activation of the MAP kinase pathway is frequently found in many types of cancer. Recently, activating mutations in the BRAF gene, an important activator of this pathway, have been described in several tumor types including melanoma, colorectal and papillary thyroid cancer. The most frequent mutation in exon 15 (V600E) as well as several other mutations within exons 11 and 15 result in constitutive activation of the oncoprotein.

Materials and methods

Our study aimed to investigate BRAF mutations in 30 human bladder tumors and their adjacent normal tissues. The V600E mutation was screened by PCR/RFLP and exons 11, 14 and 15 of BRAF including intron-exon boundaries were sequenced.

Results

We detected two tumor specimens bearing two different mutations, both of which were found in exon 15. One sample showed the T1799A (V600E) and the other the G1798T (V600L) mutation. The first specimen was stage pT1a and grade II, whereas the second was stage pT2b and grade III. No mutations within the coding region of exons 11, 14, 15 and the intron-exon junctions for the remaining samples were found.

Conclusions

Our results suggest that involvement of BRAF mutations in the development of transitional cell carcinoma of the bladder is infrequent.

α-Lipoic acid suppresses migration and invasion via downregulation of cell surface β1-integrin expression in bladder cancer cells

Our previous study showed α-lipoic acid (LA) downregulated cell surface β1-integrin expression of v-H-ras-transformed derivative of rat fibroblast with amelioration of their malignant phenotype. Here, we evaluated the ameliorating effect of LA on the malignant characters in H-ras-transformed bladder cancer cells. H-ras mutated bladder cancer line, T24 cells were incubated with LA to evaluate the inhibitory effect on proliferation, migration, invasion and β1-integrin expression. Fluorescence staining of F-actin and western blotting analyses of the related signaling pathways were also performed. LA inhibited the proliferation of T24 cells. Cell adhesion to collagen IV and fibronectin was strikingly inhibited by LA treatment accompanied by downregulation of cell surface but not whole cell β1-integrin expression. LA clearly inhibited cell migration and invasion of T24 cells, which were mimicked by extracellular signal-regulated kinase (ERK) and Akt pathway inhibition. Actually, LA significantly downregulated the phosphorylated ERK and Akt levels. Moreover, LA downregulated phosphorylated focal adhesion kinase level with disappearance of stress fiber formation. Finally, although LA induced the internalization of cell surface β1-integrin, disruption of the raft did not affect the action of LA. Taken together, LA is a promising agent to improve malignant character of bladder cancer cells through regulation of cellular β1-integrin localization.

Spotlight on differentially expressed genes in urinary bladder cancer

INTRODUCTION

We previously identified common differentially expressed (DE) genes in bladder cancer (BC). In the present study we analyzed in depth, the expression of several groups of these DE genes.

MATERIALS AND METHODS

Samples from 30 human BCs and their adjacent normal tissues were analyzed by whole genome cDNA microarrays, qRT-PCR and Western blotting. Our attention was focused on cell-cycle control and DNA damage repair genes, genes related to apoptosis, signal transduction, angiogenesis, as well as cellular proliferation, invasion and metastasis. Four publicly available GEO Datasets were further analyzed, and the expression data of the genes of interest (GOIs) were compared to those of the present study. The relationship among the GOI was also investigated. GO and KEGG molecular pathway analysis was performed to identify possible enrichment of genes with specific biological themes.

RESULTS

Unsupervised cluster analysis of DNA microarray data revealed a clear distinction in BC vs. control samples and low vs. high grade tumors. Genes with at least 2-fold differential expression in BC vs. controls, as well as in non-muscle invasive vs. muscle invasive tumors and in low vs. high grade tumors, were identified and ranked. Specific attention was paid to the changes in osteopontin (OPN, SPP1) expression, due to its multiple biological functions. Similarly, genes exhibiting equal or low expression in BC vs. the controls were scored. Significant pair-wise correlations in gene expression were scored. GO analysis revealed the multi-facet character of the GOIs, since they participate in a variety of mechanisms, including cell proliferation, cell death, metabolism, cell shape, and cytoskeletal re-organization. KEGG analysis revealed that the most significant pathway was that of Bladder Cancer (p = 1.5×10(-31)).

CONCLUSIONS

The present work adds to the current knowledge on molecular signature identification of BC. Such works should progress in order to gain more insight into disease molecular mechanisms.

Ras Isoprenylation and pAkt Inhibition by Zoledronic Acid and Fluvastatin Enhances Paclitaxel Activity in T24 Bladder Cancer Cells

Background

Bisphosphonates interfere with the mevalonate pathway and inhibit the prenylation of small GTP-binding proteins such as ras and rap. We hypothesized that zoledronic acid would synergistically inhibit T24 bladder cancer cell growth in combination with fluvastatin and paclitaxel.

Methods

Increasing doses of fluvastatin, zoledronic acid, and paclitaxel were investigated as single agents and in combination, and synergistic interactions were evaluated by the Chou-Talalay method. Western blots were used to assess effects on signal transduction pathways.

Results

Growth of T24 was significantly inhibited with IC₅₀ values of 2.67 ± 0.61 μM for fluvastatin and 5.35 ± 1.35 μM for zoledronic acid after 72 hours treatment. Geranylgeranyl pyrophosphate and farnesyl pyrophosphate was able to block, in part, this inhibitory activity. The combinations of zoledronic acid and paclitaxel, zoledronic acid and fluvastatin, and fluvastatin and paclitaxel were all synergistic. Both fluvastatin and zoledronic acid inhibited Ras and Rap prenylation, and the phosphorylation of ERK1/2 and AKT. The degree of inhibition of phosphorylation of these key signaling transduction pathways appears to closely correlate with their synergistic interactions.

Conclusions

Zoledronic acid enhances fluvastatin and paclitaxel activity against T24 in a synergistic manner and this is mediated largely by inhibition of both the Ras/Raf/MEK/ERK and PI3K/AKT signaling pathways via isoprenylation inhibition.

Inhibitory effect of flavonoids on mutant H-Rasp protein

Mutant form of H-Ras (Harvey-Ras) proteins are found in almost 10%-25% of human tumours. Mutational activation transforms it into an oncogenic form, which results in the loss of intrinsic GTPase function and therefore the protein is constitutively in the active, GTP-bound state and is continuously sending signals for cell growth and proliferation. In the present insilico study, the inhibitory effect of different flavonoid compounds on mutant H Ras protein p21 has been assessed. In addition, inhibitory effect of flavonoids is compared with 3 known anticancer drugs. Upon docking, it was found that flavonoids such as Naringenin, Daidzein, and Hesperetin showed highest affinity (most negative ΔG), while Rutin showed no affinity towards mutant H Ras. The 3 clinical anticancer agents (Erlotinib, Letrozole and Exemestane) showed binding energies in the range of -1.11 to -5.51 kcal/mol which is comparatively lower than the flavonoids indicating efficacy of flavonoids in the treatment of cancer with little or no cytotoxicity. Our study demonstrates that flavonoids (particularly Naringenin, Daidzein, and Hesperetin) are the effective drugs to inhibit function of mutant H-Ras P21 protein, which in turn arrests the process of cell growth and proliferation of the cancer cell.

Molecular genesis of non-muscle-invasive urothelial carcinoma (NMIUC)

Urothelial carcinoma (UC) is the most common type of bladder cancer in Western nations. Most patients present with the non-muscle-invasive (NMIUC) form of the disease, while up to a third harbour the invasive form (MIUC). Specifically, the aetiology of NMIUC appears to be multifactorial and very different from that of MIUC. Loss of specific tumour suppressor genes as well as gain-of-function mutations in proteins within defined cellular signalling pathways have been implicated in NMIUC aetiology. The regions of chromosome 9 that harbour CDKN2A, CDKN2B, TSC1, PTCH1 and DBC1 are frequently mutated in NMIUC, resulting in functional loss; in addition, HRAS and FGFR3, which are both proto-oncogenes encoding components of the Ras-MAPK signalling pathway, have been found to harbour activating mutations in a large number of NMIUCs. Interestingly, some of these molecular events are mutually exclusive, suggesting functional equivalence. Since several of these driving changes are amenable to therapeutic targeting, understanding the signalling events in NMIUC may offer novel approaches to manage the recurrence and progression of this disease.

Management of bladder cancer: current and emerging strategies

Cancer of the urinary bladder is the fifth most prevalent solid tumour in the US. Urothelial carcinoma is the most common form of bladder cancer, accounting for about 90% of cases. About 25% of patients with bladder cancer have advanced disease (muscle-invasive or metastatic disease) at presentation and are candidates for systemic chemotherapy. Urothelial carcinoma is a chemo-sensitive disease, with a high overall and complete response rate to combination chemotherapy. In the setting of muscle-invasive urothelial carcinoma, use of neoadjuvant chemotherapy is associated with overall survival benefit. The role of adjuvant chemotherapy in this setting is yet to be validated. In the setting of metastatic disease, use of cisplatin-based regimens improves survival. However, despite initial high response rates, the responses are typically not durable leading to recurrence and death in the vast majority of these patients. Currently, there is no standard second-line therapy for patients in whom first-line chemotherapy for metastatic disease has failed. Many newer chemotherapeutic agents have shown modest activity in urothelial carcinoma. Improved understanding of molecular biology and pathogenesis of urothelial carcinoma has opened avenues for the use of molecularly targeted therapies, several of which are being tested in clinical trials. Currently, several novel drugs seem particularly promising including inhibitors of the epidermal growth factor receptor pathway, such as cetuximab, and inhibitors of tumour angiogenesis, such as bevacizumab and sunitinib. Development of reliable molecular predictive markers is expected to improve treatment decisions, therapy development and outcomes in urothelial carcinoma. Funding of and participation in clinical trials are key to advancing the care of urothelial cancer patients. Current and emerging strategies in the medical management of urothelial carcinoma are reviewed.

Vascular endothelial growth factor, p53, and the H-ras oncogene in Egyptian patients with bladder cancer

AIM: To evaluate the relationship between vascular endothelial growth factor (VEGF), p53, and the H-ras oncogene and different clinicopathological parameters in Egyptian patients with Schistosoma-associated transitional cell carcinoma of the bladder.

METHODS: The study included 50 patients with transitional cell carcinoma for whom radical cystectomy and urinary diversions were carried out. VEGF and p53 protein expressions were evaluated with an immunohistochemical staining method, and H-ras oncogene mutations were analyzed with a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique.

RESULTS: High grade tumors revealed higher p53 immunostaining than low grade tumors (P = 0.016). p53 and VEGF protein expressions, as well as H-ras oncogene mutations, had an insignificant impact on patient outcomes (P = 0.962, P = 0.791, and P = 967, respectively). Cancer extension to regional lymph nodes was associated with poor outcomes (P = 0.008).

CONCLUSION: VEGF, p53 and the H-ras oncogene have no relation to patient survival and outcome in Schistosoma-associated transitional cell carcinoma.

Bladder cancer: modeling and translation

Transitional cell carcinoma of the bladder is a common malignancy worldwide that is associated with significant morbidity and mortality. Although superficial tumors can often be treated effectively, invasive cancers not only require invasive surgery, but are also refractory to aggressive chemotherapy and radiotherapy. In this issue of Genes & Development, Puzio-Kuter and colleagues (pp. 675-680) describe an elegant genetically engineered murine model of bladder cancer that recapitulates many of the cardinal features of the human disease. The development of such models together with the application of new approaches to enumerate the complement of genetic alterations in bladder will provide new insights into the molecular nature of this disease. Moreover, the anatomy of this urinary malignancy provides a unique opportunity for innovative translational studies.

Activation of RAS family genes in urothelial carcinoma

PURPOSE

Bladder cancer is the fifth most common malignancy in men in Western society. We determined RAS codon 12 and 13 point mutations and evaluated mRNA expression levels in transitional cell carcinoma cases.

MATERIALS AND METHODS

Samples from 30 human bladder cancers and 30 normal tissues were analyzed by polymerase chain reaction/restriction fragment length polymorphism and direct sequencing to determine the occurrence of mutations in codons 12 and 13 of RAS family genes. Moreover, we used real-time reverse transcriptase-polymerase chain reaction to evaluate the expression profile of RAS genes in bladder cancer specimens compared to that in adjacent normal tissues.

RESULTS

Overall H-RAS mutations in codon 12 were observed in 9 tumor samples (30%). Two of the 9 patients (22%) had invasive bladder cancer and 7 (77%) had noninvasive bladder cancer. One H-RAS mutation (11%) was homozygous and the remaining 89% were heterozygous. All samples were WT for K and N-RAS oncogenes. Moreover, 23 of 30 samples (77%) showed over expression in at least 1 RAS family gene compared to adjacent normal tissue. K and N-RAS had the highest levels of over expression in bladder cancer specimens (50%), whereas 27% of transitional cell carcinomas demonstrated H-RAS over expression relative to paired normal tissues.

CONCLUSIONS

Our results underline the importance of H-RAS activation in human bladder cancer by codon 12 mutations. Moreover, they provide evidence that increased expression of all 3 RAS genes is a common event in bladder cancer that is associated with disease development.

Behavioral genetics of the depression/cancer correlation: a look at the Ras oncogene family and the 'cerebral diabetes paradigm'

This study investigates the causes of the observed linkage between depression and later onset of cancer. The prevailing view is that cancer in depressed patients results from a weakened immune system. However, molecular biologists have recognized that dysregulation of the ras proto-oncogene results in impaired serotonin and dopamine synthesis manifesting as major depression. A qualitative review of the literature showed that (1) studies using the Minnesota Multiphasic Personality Inventory showed a greater correlation between depression and later cancer onset than those employing other measures and (2) the more related the cancer type was to the Ras oncogene family, the greater the correlation between depression and later cancer onset. These results support the hypothesis that the ras proto-oncogene plays a role in the etiology of depression and could be the common denominator in long-observed depression/cancer linkages. Previous depression/cancer linkage studies are confounded in that they failed to analyze cancer type and accurately diagnose depression.

Proteome-based diagnostics and prognosis of bladder transitional cell carcinoma

More than 90% of bladder tumors are diagnosed as bladder transitional cell carcinoma and the majority of these lesions (70%) are diagnosed as superficial papillary lesions (stage pTa, T1). Recurrences are common to superficial tumors and few lesions will progress to a higher grade and/or stage and muscle invasion. Thus, diagnosing cancer at an early stage, predicting whether a tumor will recur and/or progress and identification of novel targets for cancer intervention, become the main focus of bladder cancer research. The purpose of this article is to briefly review what has been accomplished to date by using proteomic technology in order to develop a new strategy to resolve the problems of early detection, recurrence or therapeutic intervention.

Search for the tumor-related proteins of transition cell carcinoma in Taiwan by proteomic analysis

To better understand the carcinogenesis of bladder cancer in Taiwan, we utilized the proteomic approach to search for potential biomarkers of transitional cell carcinoma (TCC). Analysis by 2-DE and MS/MS indicated that seven proteins are down-regulated and three proteins up-regulated in grade III samples as compared with those of grade II. Of these deregulated proteins, fatty acid binding proteins, annexin V, heat-shock protein 27, and lactate dehydrogenase have been shown to be associated with bladder cancer. Our studies also found altered expression of a group of proteins that have not been documented previously in bladder cancer, including annexin I, 15-hydroxyprostaglandin dehydrogenase, galectin-1, lysophospholipase and mitochondrial short-chain enoyl-coenzyme A hydratase 1 precursor. These results illustrate a pattern of differential protein expression between low- and high-grade tumors and it may be utilized as the molecular fingerprinting of a subset of bladder cancers. In addition, the present study provides a valuable resource in the study of pathological mechanisms in cancers of urothelial origin. The immunohistochemical staining of grade II and III TCC samples with antiserum to annexin I protein was utilized to confirm that the annexin I protein is up-regulated in grade III TCC.

H-Ras oncogene counteracts the growth-inhibitory effect of genistein in T24 bladder carcinoma cells

Among eight human bladder cancer cell lines we examined, only T24 cells were resistant to the growth inhibition effect of genistein, an isoflavone and potent anticancer drug. Since the T24 cell line was the only cell line known to overexpress oncogenic H-Ras(val 12), we investigated the role of H-Ras(val 12) in mediating drug resistance. Herein, we demonstrate that the phenotype of T24 cells could be dramatically reversed and became relatively susceptible to growth inhibition by genistein if the synthesis of H-Ras(val 12) or its downstream effector c-Fos had been suppressed. The inhibition of Ras-mediated signalling with protein kinase inhibitors, such as PD58059 and U0126 which inhibited MEK and ERK, in T24 cells also rendered the identical phenotypic reversion. However, this reversion was not observed when an inhibitor was used to suppress the protein phosphorylation function of PI3 K or PKC. These results suggest that the signal mediated by H-Ras(val 12) is predominantly responsible for the resistance of the cells to the anticancer drug genistein.

A phase II trial of R115777, an oral farnesyl transferase inhibitor, in patients with advanced urothelial tract transitional cell carcinoma

BACKGROUND

R115777 is a potent farnesyl transferase inhibitor and has significant antitumor effects in vitro and in vivo.

METHODS

The objective of the current study was to determine the objective response proportion in patients with metastatic transitional cell carcinoma (TCC) of the urothelial tract who received treatment with R115777 at a dose of 300 mg orally given twice daily for 21 days followed by 7 days of rest for every 4-week cycle. Thirty-four patients with TCC were enrolled in this Phase II study. Patients were allowed to have received a maximum of one prior systemic chemotherapy regimen, not including chemoradiation or neoadjuvant chemotherapy. All patients were required to have an Eastern Cooperative Oncology Group performance status of 0-2 and adequate bone marrow, hepatic, and kidney function.

RESULTS

Twice daily administration of oral R115777 was tolerated well. R115777 was absorbed rapidly after oral administration. Grade 3-4 neutropenia (according to the National Cancer Institute Common Toxicity Criteria [version 2.0]) was observed in 5 patients (15%). Grade 3-4 nonhematologic toxicity was rare, consisting of rash and diarrhea in 1 patient each. Two patients (6%) without prior chemotherapy demonstrated partial responses. Thirteen patients (38%) achieved disease stabilization according to World Health Organization criteria that lasted a median of 4 months. No complete responses were observed.

CONCLUSIONS

The objective response rate of R115777 was not sufficient to warrant future investigation in TCC as a single agent. Preliminary evidence of the activity of R115777 in 2 chemotherapy-naive patients may warrant further investigation in combination with first-line chemotherapy.

Non-invasive screening of fragile X syndrome A using urine and hair roots

The diagnosis of fragile X A syndrome (FRAXA) during childhood depends largely on DNA-based diagnostic tests due to the lack of the specific clinical features. To determine a non-invasive screening method for fragile X syndrome, we studied the method of DNA-based diagnosis using urine or hair roots instead of routinely used peripheral blood cells. The amplification of repeat-containing alleles of FMR-1 by PCR using Pfu polymerase was applied on DNA extracted from urine sediments or hair roots of 50 and 28 normal individuals, respectively. Consistent amplification of repeat-containing DNA fragments of normal size to ethidium-visible quantities were obtained in 92% (46/50) of urine samples and 100% (28/28) of hair roots. No bands of normal size or abnormal or artificial smears were detected in two male FRAXA patients. No female samples were examined in the present study because the separation of two alleles was unsatisfactory on agarose gels with DNA from blood samples. Our results indicate that the use of hair roots in a DNA-based test constitutes a rapid, simple and less-invasive screen to diagnose males with FRAXA.

The role of Ras superfamily proteins in bladder cancer progression

PURPOSE

The prognosis of patients with bladder cancer is strongly dependent on whether the lesion is superficial or invasive at initial presentation. In addition, a significant fraction of patients presenting with superficial disease have invasive tumor during followup. Understanding how superficial bladder cancer progresses to invasive forms of the disease is of paramount importance for early diagnosis and successful treatment. Molecular mechanisms underlying bladder cancer progression are being elucidated. We reviewed the roles that members of the Ras superfamily of monomeric G proteins, an important class of cellular regulator, have in bladder cancer and its progression.

MATERIALS AND METHODS

We performed MEDLINE searches focusing on members of the Ras superfamily of monomeric G proteins and their involvement in transitional cell carcinoma, which is the most common form of bladder cancer. General involvement in cancer of key superfamily members, focusing on mechanisms and downstream pathways, was also reviewed through MEDLINE and manual bibliographic searches.

RESULTS

With more than 100 members in humans the Ras superfamily is a diverse group of monomeric G proteins. These proteins regulate many cellular processes, such as cell cycle progression, actin cytoskeletal dynamics and membrane traffic. Members of the Ras and Rho family are also known to be involved in human cancer through mutation, over expression and dysregulation. In this review we focus on bladder cancer. In particular we focus on how H-Ras, RalA/B and RhoGDI2, a regulator of Rho family members, participate in bladder cancer progression and how their participation may be related to other molecules associated with bladder cancer progression, such as epidermal growth factor receptor, p53 and PTEN (phosphatase and tensin homologue deleted on chromosome 10).

CONCLUSIONS

The findings discussed offer the hopeful possibility that signaling pathways mediated by Ras superfamily members may offer new opportunities for diagnostic and therapeutic interventions in bladder cancer.

Ras oncogene mutations in urine sediments of patients with bladder cancer

Early detection of bladder cancer is particularly important since it dramatically affects the survival rates. However, neither urinary cytology nor tumor markers that are currently used are sensitive enough for the early detection of bladder cancer or recurrent disease. The ras genes are frequently mutated in cancer. In this study, we investigated the diagnostic potential of ras mutation analysis in urinary sediments of patients with bladder cancer using a single-strand conformation polymorphism analysis and polymerase chain reaction. Mutation in codon 12 of the H-ras gene was observed in 39% of the patients. Our results indicate that this approach may significantly improve diagnostic sensitivity in detecting bladder tumors.

Farnesyltransferase inhibitors potentiate the antitumor effect of radiation on a human tumor xenograft expressing activated HRAS

Successful radiosensitization requires that tumor cells become more radiosensitive without causing an equivalent reduction in the survival of cells of the surrounding normal tissues. Since tumor cell radiosensitivity can be influenced by RAS oncogene activation, we have hypothesized that inhibition of oncogenic RAS activity would lead to radiosensitization of tumors with activated RAS. We previously showed in tissue culture that prenyltransferase treatment of cells with activated RAS resulted in radiosensitization, whereas treatment of cells with wild-type RAS had no effect on radiation survival. Here we ask whether the findings obtained in vitro have applicability in vivo. We found that treatment of nude mice bearing T24 tumor cell xenografts with farnesyltransferase inhibitors resulted in a significant and synergistic reduction in tumor cell survival after irradiation. The regrowth of T24 tumors expressing activated RAS was also significantly prolonged by the addition of treatment with farnesyltransferase inhibitors compared to the regrowth after irradiation alone. In contrast, there was no effect on the radiosensitivity of HT-29 tumors expressing wild-type RAS. These results demonstrate that specific radiosensitization of tumors expressing activated RAS oncogenes can be obtained in vivo.

Urinary markers of malignancy

Transitional cell carcinoma (TCC) is the second most common malignancy in the genitourinary tract. The majority of urothelial tumors are superficial when the patient first presents, but despite adequate resection of the primary lesion the recurrence rate is particularly high. In a small but significant group of patients the tumor is primary invasive or subsequently can progress and leads to death. Voided urine can be easily obtained and therefore diagnostic urine tests would be ideal for screening or follow up of TCC. Although many urinary markers have been described, none of them is used routinely in clinical practice. Promising tumor markers still need to be evaluated in multi-center clinical studies. Larger prospective trials are necessary in order to identify prognostic indicators that would help to predict disease progression or response to different treatment modalities (BCG, chemo-, radiotherapy, etc.). Hopefully, new diagnostic urine tests will allow to identify patients who will most benefit from early cystectomy with or without adjuvant treatment, bladder sparing protocols or systemic treatment. In this paper we have reviewed the literature and discuss, from the clinician's point of view, the current status of various diagnostic tests for urinary markers. [Lee SJ, Lee WE, Chang SG, Lee CH, Kim JI. A comparative study of telomerase, Lewis X, BTA, NMP22 and urinary cytology in bladder tumor. J Urol 1999;161(suppl):152.]

Presence of Donor- and Recipient-derived DNA in Cell-free Urine Samples of Renal Transplantation Recipients: Urinary DNA Chimerism

Background: Previous studies have indicated that microchimerism is present in body tissues, peripheral blood, and plasma of recipients after organ transplantation. We hypothesize that donor-derived DNA may also be present in cell-free urine of renal transplant recipients and that the concentrations of urine DNA may be correlated with graft rejection.

Methods: Thirty-one female patients who had renal transplantation were enrolled in the study. In women with male organ donors, the SRY gene on the Y chromosome was used as a marker for donor-derived DNA. Real-time quantitative PCR for the SRY and β-globin genes was carried out on cell-free urinary DNA from these patients. Serial urine samples from a female renal transplant recipient undergoing an acute rejection episode were also collected and analyzed with the β-globin quantitative PCR system.

Results: SRY sequences were detected in the urine of 14 of 17 female patients with male organ donors. None of the 14 patients with female organ donors had detectable SRY sequences in urinary DNA. The median fractional concentration of donor-derived DNA was 8.7% (interquartile range, 1.9–26.4%). During the acute rejection episode, urinary concentrations of the β-globin gene were markedly increased, with the concentrations returning rapidly to normal following antirejection treatment.

Conclusions: Our results demonstrate that urinary DNA chimerism is present following renal transplantation. The measurement of urinary DNA using quantitative PCR may be useful for the diagnosis and monitoring of graft rejection.

Malignant fibrous histiocytomas and H-ras-1 oncogene point mutations

AIMS

To investigate the types and the frequencies of H-ras-1 gene mutations in malignant fibrous histiocytomas.

METHODS

Thirty five samples of malignant fibrous histiocytoma tissue were searched for point mutations within "hot spot" codons 12 and 13 of the H-ras-1 oncogene by the specific "nested" polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) and a direct cycle sequencing procedure.

RESULTS

In contrast to previous reports, none of the tumours contained a point mutation or any other changes within or around the hot spot gene sequences.

CONCLUSIONS

These data indicate that H-ras-1 oncogenic activation is not required in the molecular pathway of malignant fibrous histiocytoma formation and cannot be used as a discriminating factor for diagnostic sarcoma typing.

Inhibition of human bladder cancer cell motility by genistein is dependent on epidermal growth factor receptor but not p21ras gene expression

A significant portion of patients who present with non-muscle invasive "superficial" bladder cancer develop the muscle "invasive" life-threatening form of the disease during subsequent follow-up. In clinical studies, overexpression of the epidermal growth factor receptor (EGFR) and the p21 ras oncogene have been strongly associated with this phenotypic tumor transition. The marked difference in incidence of invasive bladder cancer in Asia compared to the United States has made us hypothesize that, among other factors, dietary influences have an impact on such tumor progression. A significantly higher dietary consumption of soy products exists in Asia and has led to the notion that the isoflavones present in this diet may contribute to a reduction in the number of invasive transitional cell bladder cancers. In this regard, we sought to determine the effect of genistein, a naturally occurring dietary protein tyrosine kinase (PTK) inhibitor, on the growth and motility of human bladder cancer cell lines with diverse EGFR and p21ras expression phenotypes and corresponding invasive behaviors. These effects were compared with those of tyrphostin, a pure synthetic EGFR inhibitor. Our results indicate that both genistein and tyrphostin are effective inhibitors of bladder cancer motility and growth, key factors in the development of muscle invasive disease. In addition, the growth and motility inhibitory effects of genistein and tyrphostin are observed preferentially in cells that overexpress the EGFR. Cells that have a mutated p21ras but do not overexpress the EGFR are less inhibited by these 2 compounds, suggesting that their effect is primarily directed at the EGFR signal transduction pathways proximal to the p21ras gene. Our results would seem to corroborate the notion that a high dietary intake of isoflavones is a likely explanation for the decreased incidence of invasive bladder cancer.