Bernard Malavaud

Sphingosine Kinase-1 as a Chemotherapy Sensor in Prostate Adenocarcinoma Cell and Mouse Models

Systemic chemotherapy was considered of modest efficacy in prostate cancer until the recent introduction of taxanes. We took advantage of the known differential effect of camptothecin and docetaxel on human PC-3 and LNCaP prostate cancer cells to determine their effect on sphingosine kinase-1 (SphK1) activity and subsequent ceramide/sphingosine 1-phosphate (S1P) balance in relation with cell survival. In vitro, docetaxel and camptothecin induced strong inhibition of SphK1 and elevation of the ceramide/S1P ratio only in cell lines sensitive to these drugs. SphK1 overexpression in both cell lines impaired the efficacy of chemotherapy by decreasing the ceramide/S1P ratio. Alternatively, silencing SphK1 by RNA interference or pharmacologic inhibition induced apoptosis coupled with ceramide elevation and loss of S1P. The differential effect of both chemotherapeutics was confirmed in an orthotopic PC-3/green fluorescent protein model established in nude mice. Docetaxel induced a stronger SphK1 inhibition and ceramide/S1P ratio elevation than camptothecin. This was accompanied by a smaller tumor volume and the reduced occurrence and number of metastases. SphK1-overexpressing PC-3 cells implanted in animals developed remarkably larger tumors and resistance to docetaxel treatment. These results provide the first in vivo demonstration of SphK1 as a sensor of chemotherapy.

Validation of the European Society of Urogenital Radiology Scoring System for Prostate Cancer Diagnosis on Multiparametric Magnetic Resonance Imaging in a Cohort of Repeat Biopsy Patients

BACKGROUND Wide variations in acquisition protocols and the lack of robust diagnostic criteria make magnetic resonance imaging (MRI) detection of prostate cancer (PCa) one of the most challenging fields in radiology and urology. OBJECTIVE To validate the recently proposed European Society of Urogenital Radiology (ESUR) scoring system for multiparametric MRI (mpMRI) of the prostate. DESIGN, SETTING, AND PARTICIPANTS An institutional review board-approved multicentric prospective study; 129 consecutive patients (1514 cores) referred for mpMRI after at least one set of negative biopsies. INTERVENTION Transfer of mpMRI-suspicious areas on three-dimensional (3D) transrectal ultrasound images by 3D elastic surface registration; random systematic and targeted cores followed by core-by-core analysis of pathology and mpMRI characteristics of the core locations. The ESUR scores were assigned after the procedure on annotated Digital Imaging and Communications in Medicine archives. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Relationships between ESUR scores and biopsy results were assessed by the Mann-Whitney U test. The Yates correction and Pearson χ(2) tests evaluated the association between categorical variables. A teaching set was randomly drawn to construct the receiver operating characteristic curve of the ESUR score sum (ESUR-S). The threshold to recommend biopsy was obtained from the Youden J statistics and tested in the remaining validation set in terms of sensitivity, specificity, positive predictive value, negative predictive value, and accuracy. RESULTS AND LIMITATIONS Higher T2-weighted, dynamic weighted imaging and dynamic contrast-enhanced ESUR scores were observed in areas yielding cancer-positive cores. The proportion of positive cores increased with the ESUR-S aggregated in five increments (ESUR-S 3-5: 2.9%; ESUR-S 6-8: 11.1%; ESUR-S 9-10: 38.2%; ESUR-S 11-12: 63.4%; and ESUR-S 13-15: 83.3%; p<0.0001). A threshold of ESUR-S ≥ 9 exhibited the following characteristics: sensitivity: 73.5%; specificity: 81.5%; positive predictive value: 38.2%; negative predictive value: 95.2%; and accuracy: 80.4%. Although the study was not designed to compare repeat biopsy strategies, more targeted cores than random systematic cores were found to be positive for cancer (36.3% compared with 4.9%, p<0.00001). CONCLUSIONS In the challenging situation of repeat biopsies, the ESUR scoring system was shown to provide clinically relevant stratification of the risk of showing PCa in a given location.

Complications for Radical Cystectomy

Objectives: To report the perioperative events after radical cystectomy and urinary diversion in bladder cancer in terms of major and minor complications and to seek statistical relationships with patient’s characteristics and surgical procedures. Methods: One hundred and sixty–one radical cystectomies performed in the modern era in two academic hospitals were reviewed. Preoperative patients characteristics (age, sex, hemoglobin, total protein, weight and height) and perioperative data (operative time, type of urinary diversion, associated procedures, blood transfusion, seniority of the surgeon) were recorded. Perioperative morbidity was defined by any adverse event during hospital stay or within 30 days after surgery, those requesting an additional stay of more that 3 days in the intensive care unit or a reoperation being classified as major complications. Significant relationships were sought for classes by Student’s t test for comparison of quantitative variables and Yate’s corrected χ2 test for categorical variables. Spearman’s rank correlation test was used for comparison of quantitative variables. Results: Major complications were observed in 41 patients (25.5%) and resulted in 14 reoperations (8.7% reoperation rate). Most of them were diversion–related and were statistically related to the ASA score ≧3 (p<0.01, 5.7 odds ratio). Compared to sophisticated means of diversion, cutaneous diversion resulted in minimal operative time and hospital stay. No relationships between age, body mass index, biological parameters, type of diversion, associated procedure, surgeon’s experience and postoperative complications could be evidenced. Uneventful recovery resulted in a 16.6 days mean hospital stay, minor complications induced a significant 3.8 days additional stay and major complications resulted in major lengthening of hospital stay (21.2 days mean additional stay). Conclusion: ASA scores equal to or greater than 3 were associated with major complications and most specially those related to the type of urinary diversion. Therefore, we recommend special care in the selection of the type of urinary diversion and further preoperative evaluation inclusive of nutritional assessment.

BCG Intravesical Instillations: Recommendations for Side-Effects Management

Adverse events following intravesical BCG therapy are related to strain virulence, allergic reactions or to nosocomial urinary tract infections. Low grade fever and irritative symptoms are common side-effects of BCG. They subside within 48 hours and do not require any specific treatment, apart from standard painkillers and antispasmodics. Further instillations should be postponed until symptoms have resolved completely. If symptoms do not resolve, complementary investigations are recommended including urine culture, and isoniazid may be prescribed for 15 days. The BCG dose should be reduced if symptoms increase after subsequent instillations. Complications of BCG infection – either local or systemic – have been reported with an incidence of 10–15%. These complications include: granulomatous prostatitis or epididymitis (treated with isoniazid and rifampicin for 3 months), contracted bladder may occur, mainly during maintenance courses, systemic infection such as granulomatous nephritis and abscesses, pneumonitis, hepatitis, osteomyelitis (treated with isoniazid, rifampicin and ethambutol for 6 months), and life-threatening adverse events may be related to septicaemia or to immunoallergic reactions, the onset of which may be delayed several months after the end of BCG therapy. Such conditions require urgent treatment with standard antituberculous antibiotics and prednisolone. These complications are an absolute contraindication for further BCG instillations. Despite its toxicity, the risk-benefit ratio favours the use of BCG in patients who have moderate- and high-risk tumours.

Sphingosine Kinase 1: A New Modulator of Hypoxia Inducible Factor 1α during Hypoxia in Human Cancer Cells

Here, we provide the first evidence that sphingosine kinase 1 (SphK1), an oncogenic lipid kinase balancing the intracellular level of key signaling sphingolipids, modulates the transcription factor hypoxia inducible factor 1alpha (HIF-1alpha), master regulator of hypoxia. SphK1 activity is stimulated under low oxygen conditions and regulated by reactive oxygen species. The SphK1-dependent stabilization of HIF-1alpha levels is mediated by the Akt/glycogen synthase kinase-3beta signaling pathway that prevents its von Hippel-Lindau protein-mediated degradation by the proteasome. The pharmacologic and RNA silencing inhibition of SphK1 activity prevents the accumulation of HIF-1alpha and its transcriptional activity in several human cancer cell lineages (prostate, brain, breast, kidney, and lung), suggesting a canonical pathway. Therefore, we propose that SphK1 can act as a master regulator for hypoxia, giving support to its inhibition as a valid strategy to control tumor hypoxia and its molecular consequences.

Chemosensitizing effects of sphingosine kinase-1 inhibition in prostate cancer cell and animal models

We have previously reported that, in prostate cancer, inhibition of the oncogenic sphingosine kinase-1/sphingosine 1-phosphate (SphK1/S1P) pathway is a key element in chemotherapy-induced apoptosis. Here, we show that selective pharmacologic inhibition of SphK1 triggers apoptosis in LNCaP and PC-3 prostate cancer cells, an effect that is reversed by SphK1 enforced expression. More importantly, we show for the first time that the up-regulation of the SphK1/S1P pathway plays a crucial role in the resistance of prostate cancer cells to chemotherapy. Importantly, pharmacologic SphK1 inhibition with the B-5354c compound sensitizes LNCaP and PC-3 cells to docetaxel and camptothecin, respectively. In vivo, camptothecin and B-5354c alone display a limited effect on tumor growth in PC-3 cells, whereas in combination there is a synergy of effect on tumor size with a significant increase in the ceramide to S1P sphingolipid ratio. To conclude, our study highlights the notion that drugs specifically designed to inhibit SphK1 could provide a means of enhancing the effects of conventional treatment through the prosurvival antiapoptotic SphK1/S1P pathway. [Mol Cancer Ther 2008;7(7):1836–45]

Nosocomial outbreak of influenza virus A (H3N2) infection in A solid organ transplant department

Background. There is a strong body of evidence in favor of influenza virus immunization in solid organ recipients. However, little attention has been devoted to other reservoirs, such as the patients’ relatives and, at the time of hospital admission, to the healthcare workers. Methods. Analysis of the epidemiology of an outbreak of nosocomial influenza A in a solid organ transplant unit. Results. Four cases of influenza A virus infection were reported during a short 4-day outbreak in a 12 single-room transplant unit. None of the patients had been immunized against influenza. Three patients had not been visited by their relatives between admission and influenza infection. Three nurses, among the 27 healthcare workers, presented with clinical flu symptoms at times consistent with nosocomial transmission. Conclusions. Because the prevention of influenza infection by vaccination warrants a global strategy to target the different reservoirs, we suggest that the modern policy of vaccinating solid organ patients should be extended both to their relatives and to the healthcare workers of transplant units.

FTY720 (Fingolimod) Sensitizes Prostate Cancer Cells to Radiotherapy by Inhibition of Sphingosine Kinase-1

Radiotherapy is widely used as a radical treatment for prostate cancer, but curative treatments are elusive for poorly differentiated tumors where survival is just 15% at 15 years. Dose escalation improves local response rates but is limited by tolerance in normal tissues. A sphingosine analogue, FTY720 (fingolimod), a drug currently in phase III studies for treatment of multiple sclerosis, has been found to be a potent apoptosis inducer in prostate cancer cells. Using in vitro and in vivo approaches, we analyzed the impact of FTY720 on sphingolipid metabolism in hormone-refractory metastatic prostate cancer cells and evaluated its potential as a radiosensitizer on cell lines and prostate tumor xenografts. In prostate cancer cell lines, FTY720 acted as a sphingosine kinase 1 (SphK1) inhibitor that induced prostate cancer cell apoptosis in a manner independent of sphingosine-1-phosphate receptors. In contrast, γ irradiation did not affect SphK1 activity in prostate cancer cells yet synergized with FTY720 to inhibit SphK1. In mice bearing orthotopic or s.c. prostate cancer tumors, we show that FTY720 dramatically increased radiotherapeutic sensitivity, reducing tumor growth and metastasis without toxic side effects. Our findings suggest that low, well-tolerated doses of FTY720 could offer significant improvement to the clinical treatment of prostate cancer.

High prevalence of erectile dysfunction after renal transplantation.

BACKGROUND AND METHODS A cross-sectional study of multifaceted male sexual function in 323 consecutive kidney transplant recipients was conducted by mail by means of the validated International Index of Erectile Function (IIEF). All five IIEF domains (IIEF-5), i.e., erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction, were scored for each responder. IIEF-5 scoring that conformed to the National Institutes of Health definition of erectile dysfunction (ED) was computed for all patients sexually active within the past 4 weeks. RESULTS Two hundred and seventy-one patients replied. Compared to the controls used for IIEF psychometric validation, kidney transplant recipients gave lower erectile function (P<0.01) and intercourse satisfaction (P<0.05) scores, despite their being younger. ED, according to the IIEF-5 method, was demonstrated in 55.7% of the sexually active patients (n=212). Age, time on dialysis, and iterative transplants were significantly and negatively related to erectile dysfunction. CONCLUSION IIEF proved to be a valuable means of unveiling highly prevalent erectile dysfunction in male kidney transplant recipients. The negative impact of the time on dialysis was emphasized in the results.

Periprostatic adipocytes act as a driving force for prostate cancer progression in obesity

Obesity favours the occurrence of locally disseminated prostate cancer in the periprostatic adipose tissue (PPAT) surrounding the prostate gland. Here we show that adipocytes from PPAT support the directed migration of prostate cancer cells and that this event is strongly promoted by obesity. This process is dependent on the secretion of the chemokine CCL7 by adipocytes, which diffuses from PPAT to the peripheral zone of the prostate, stimulating the migration of CCR3 expressing tumour cells. In obesity, higher secretion of CCL7 by adipocytes facilitates extraprostatic extension. The observed increase in migration associated with obesity is totally abrogated when the CCR3/CCL7 axis is inhibited. In human prostate cancer tumours, expression of the CCR3 receptor is associated with the occurrence of aggressive disease with extended local dissemination and a higher risk of biochemical recurrence, highlighting the potential benefit of CCR3 antagonists in the treatment of prostate cancer.