Eric A. Bissonette

Cellular interactions in the tropism of prostate cancer to bone

At autopsy ≥80% of prostate cancers have established macrometastases in marrow containing bone. The mechanism(s) to explain this remarkable level of bone involvement remain to be elucidated. We examined the adhesive and invasive behavior of prostate cancer cells to osteoblastic and human bone marrow endothelial cells (HBME‐1) in an attempt to explain the tropism of prostate cells for bone. We found an inverse relationship between adhesion and prostate cell tumorigenicity and metastatic potential. Relative cell adhesion of P69 between cell lines was 1.74‐fold (95% confidence interval [CI] = 1.15–2.64) and 1.58‐fold (95% CI = 0.94–2.68) greater at 1 hr and 2 hr, respectively, than LNCaP that was essentially equivalent to C4‐2 cells when using an osteoblastic cell line, D1 as the substrate. Similar results were acquired when HBME‐1 were used as substratum. There was a marked increase in adhesion of the poorly tumorigenic cell line P69 as compared to the cancer cells to HBME‐1. P69 adhesion was 2.78‐fold (95% CI = 1.87–4.84) and 2.0‐fold (95% CI = 1.43–2.80) greater at 1 hr and 2 hr, respectively when compared to LNCaP or C4‐2 cells. D1 cells, a bone homing osteoblastic precursor, behaved contrary to the metastatic, bone‐colonizing C4‐2 cell line and bound best to other bone cells but not as well as a non‐homing fetal bone marrow‐derived cell line, D2. Invasion of prostate cancer cells through HBME‐1 lawns was examined at 8 hr and 16 hr. In contrast to the adhesion studies, the invasion of the more aggressive C4‐2 cells was 3.46‐fold (95% CI = 1.18–10.17) and 2.65‐fold (95% CI = 1.26–5.56) greater at 8 hr and 16 hr, respectively than LNCaP cells. Similarly, LNCaP cell invasion was 1.73‐fold (95% CI = 0.69–4.37) and 2.35‐fold (95% CI = 1.41–3.93) greater at 8 hr and 16 hr, respectively than P69 cells at the invasion of HBME‐1 monolayers. At 8 hr, C4‐2 cells had 6.0‐fold (95% CI = 2.63,13.65) higher invasive potential than P69 cells. Phage display biopanning of LNCaP cells versus C4‐2 cells in vitro using 4 separate techniques repeatedly identified the same peptide in support of minimal cell surface changes associated with the ability of C4‐2 cells to metastasize to bone. As integrins are vital to cell adhesion and migration, we examined the integrin subunit expression in the prostate cell lines. The expression of integrin subunits is much higher in the nontumorigenic cell line, P69, whereas the differences in integrin expression between LNCaP and C4‐2 are negligible. Only α2 and β5 integrin subunits increase from LNCaP to C4‐2. Given that C4‐2 cells spontaneously metastasize to bone in vivo and LNCaP cells do not, these studies imply that the ability of a metastatic prostate cancer cell to colonize the bone is not completely dependent upon the ability of the cancer cell to adhere to either osteoblastic cells or to the bone marrow endothelial cell lining. Therefore, the initial interaction between the bone endothelium or stroma and prostate cells is not accurately referred to as a tropic or homing response. The invasion assay results indicate that the invasive potential of the cell more accurately reflects the bone colonizing potential of a prostate cancer cell. It is likely that bidirectional paracrine interactions, subsequent to marrow adhesion, between prostate cancer cells and the bone microenvironment are what determine the successful colonization of the bone by prostate cancer cells. Further, functional changes in surface proteins that are involved in invasion are likely to occur without major changes in levels of cell surface protein expression. Functional integrin association, substratum usage and outside in signaling are more likely to predict metastatic behavior.

Longitudinal Comparison of Sexual Function After 3-Dimensional Conformal Radiation Therapy or Prostate Brachytherapy

PURPOSEnThe risk of erectile dysfunction can influence treatment decisions for localized prostate cancer. To estimate the risk from 2 popular radiotherapies we compared erectile function and overall satisfaction with sexual function after 3-dimensional (D) conformal radiation therapy and transperineal prostate brachytherapy.nnnMATERIALS AND METHODSnA total of 128 patients with prostate cancer underwent 3-D conformal radiation therapy (median dose 70.2 Gy. to the planning target volume) and 60 underwent palladium transperineal prostate brachytherapy (median dose 90 or 115 Gy. to 80% of the prostate with or without external nonconformal beam radiation therapy. Of the 128 patients 47 (37%) also received a luteinizing hormone releasing hormone (LH-RH) agonist (3 to 4 months), whereas 26 (43%) of the 60 patients received external beam radiation therapy and LH-RH (8 to 9 months). We evaluated erectile function and overall satisfaction with questions from validated, self-administered questionnaires. Patients responded to the questions serially before any prostate cancer therapy and at regular followup visits thereafter. We used the time until a patient returned to baseline erectile function and overall satisfaction to compare treatment modalities.nnnRESULTSnMedian followup was 21 months. Of patients receiving 3-D conformal radiation therapy with or without LH-RH agonists 65% (95% CI 47% to 82%) and 67% (53% to 81%), respectively, returned to baseline overall satisfaction within 12 months after treatment versus 23% (9% to 50%) and 56% (38% to 75%) of the patients treated with transperineal prostate brachytherapy with or without external beam radiation therapy and LH-RH agonists, respectively. Reductions in overall satisfaction appeared to relate to changes in erectile function.nnnCONCLUSIONSnThese data suggest that in the absence of LH-RH agonist use 3-D conformal radiation therapy and transperineal prostate brachytherapy have a similar impact on erectile function and overall satisfaction. Differences observed in erectile function and overall satisfaction in the 2 groups of patients who received adjuvant LH-RH may be due to the different duration of therapy (3 versus 8 months). Longer followup will be needed to evaluate this hypothesis.

Utility of percutaneous intervention in the management of tunneled hemodialysis catheters.

nA variety of interventional techniques have beenndeveloped to restore function to dysfunctional tunneled hemodialysisncatheters (THC). The relative efficacies of these techniques werenevaluated retrospectively to determine which therapy might be mostnbeneficial. The records of malfunctioning THCs referred toninterventional radiology between November 1995 and December 1999 werenretrospectively reviewed. Dysfunctional THCs were studied using DSAnimages obtained while injecting contrast through the lumens of thenTHCs. The interventions performed were categorized into 1 of 5 groups:nno treatment or conservative measures such as vigorous flushing;nadvancing a guidewire through the THC to reposition the catheter tip ornto dislodge a small thrombus; catheter exchange over a guidewire;nfibrin stripping of the THC using a loop snare; or prolonged (4 or morenhr) direct thrombolytic infusion. A Cox Proportional Hazards model wasndeveloped to compare the rate of failure among the procedures. Therenwere 340 THC studies. The catheters were managed as follows: 93npatients received conservative management only, 15 had a guidewirenadvanced through the catheter, 147 underwent catheter exchange, 62 werentreated with a fibrin stripping procedure, and 23 received anthrombolytic infusion. Estimated 30-day patency rates for THCs weren38.2% for conservative management, 30.9% for guidewire manipulationnof catheter tip, 53.6% for catheter exchange, 76.1% for fibrinnstripping, and 69.8% for thrombolytic infusion. Differences among thentreatments were observed (p < 0.01) andnpairwise comparisons were made among the treatment groups. Failurenrates were significantly higher in the catheter exchangen(p <0.01) and guidewire manipulation atncatheter tip (p <0.01) groups when comparednwith the fibrin stripping group. The catheter exchange and guidewirenmanipulation groups also experienced higher rates of failure whenncompared with the thrombolytic infusion group, although the differencesnwere not statistically significant (p = 0.08, pn= 0.17, respectively). Four procedure-related complicationsnrequiring hospitalization or other intervention occurred. Three ofnthese were in the catheter exchange group with one incidence of sepsis,none drug reaction, and one hematoma. Fibrin stripping and thrombolyticninfusion provided the greatest efficacy in the treatment of poorlynfunctioning THCs, but all therapies demonstrated wide-ranging results.nCentral line exchanges did not provide a superior secondary patency andnexperienced more complications.n

Magnetic resonance urography for the assessment of potential renal donors: Comparison of the RARE technique with a low-dose gadolinium-enhanced magnetic resonance urography technique in the absence of pharmacological and mechanical intervention

The aim of this study was to determine whether magnetic resonance urography without pharmacological (diuretic) stimulation and mechanical compression allows conclusive evaluation of the urinary system in potential renal donors. In 28 consecutive patients magnetic resonance urography (MRU) was performed on a 1.5-T system. Two techniques, rapid acquisition with relaxation enhancement (RARE) and a gadolinium (Gd)-enhanced 3D fast low angle shot (FLASH) sequence were compared in the absence of adjunctive measures. Two reviewers assessed image quality, presence of artifacts and completeness of visualization of the collecting systems and ureters. Among the 53 MR urograms, there was no difference in image quality and presence of artifacts between RARE and Gd-MRU. Despite high image quality, visualization of the urinary collecting system was insufficient. Continuous visualization from the collecting system to the distal ureter was demonstrated bilaterally in only 14% of the RARE and 26% of Gd-enhanced MR urograms, respectively. Overall, Gd-enhanced MRU was superior to the RARE technique in displaying the segments of the urinary collecting system, but this difference was not found to be statistically significant. Neither the RARE technique nor the gadolinium-enhanced MRU technique is accurate enough to allow the evaluation of the collecting system and ureters in potential renal donors in the absence of pharmacological intervention and compression.

Allelic Imbalance of 8p Indicates Poor Survival in Gastric Cancer

Gastric cancer is a common tumor worldwide and a tremendous health burden. However, the underlying mechanisms of tumorigenesis in this cancers development are primarily undefined. Allelic imbalance (AI) of 8p has been reported in many cancers, yet, the target(s) of alteration and the importance of allelic imbalance on this chromosomal arm in gastric carcinoma development remained to be characterized. Our findings confirmed a high rate of AI on 8p in gastric cancers. Moreover, we demonstrated that AI on 8p, either overall or at marker D8S560, was associated with poorer survival in patients with gastric cancer. Finally, gastric cancers with a high rate of microsatellite instability were significantly associated with noncardia tumors and with female gender.

Comparison of Multistation MR Angiography with Integrated Parallel Acquisition Technique versus Conventional Technique with a Dedicated Phased-array Coil System in Peripheral Vascular Disease

PURPOSEnTo assess the impact of integrated parallel acquisition technique (iPAT) on signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), venous contamination, and overall image interpretability for peripheral magnetic resonance (MR) angiography with use of a dedicated phased-array coil system.nnnMATERIALS AND METHODSnThree-dimensional contrast material-enhanced conventional MR angiography and iPAT peripheral MR angiography was performed at three stations (pelvis, thigh, calf) in 38 consecutive patients on a 1.5-T high-performance cardiovascular system (conventional MR angiography, n=19; iPAT MR angiography, n=19). A total of 29 vessel segments per patient were analyzed. For each segment, arterial, muscle, and background signal were measured; SNR and CNR were calculated; and repeated-measures analysis of variance was performed. For each of the three stations, the degree of venous contamination and the overall confidence of interpretability were analyzed with use of ordinal logistic regression analysis accounting for correlated outcome data.nnnRESULTSnA total of 1,018 vessel segments were available for analysis (477 with conventional MR angiography, 541 with iPAT MR angiography). Compared with conventional MR angiography, iPAT MR angiography resulted in decreased SNR and CNR in the pelvis and thigh stations but no change in the calf station. The difference in the pelvis was statistically significant (P<.007 for SNR and P<0.01 for CNR). Venous contamination in the calf station was significantly less on iPAT MR angiography (P<.003), with no significant differences in the other stations. The overall confidence of interpretability with iPAT MR angiography was significantly better on the lower station (P<.008).nnnCONCLUSIONSniPAT MR angiography leads to reduced SNR and CNR in the pelvis and thigh, but this does not affect interpretability of images obtained at these stations. The temporal gain results in significantly increased interpretability as a result of less venous contamination in the calf station. iPAT MR angiography is superior to conventional MR angiography for peripheral imaging.

Low-dose IL-2 induces cytokine cascade, eosinophilia, and a transient Th2 shift in melanoma patients

Purpose: To assess changes in serum cytokine levels in patients treated concomitantly with or without systemic low-dose IL-2. Vaccination targeted CTL responses to peptide antigens, and IL-2 was coadministered to expand activated CTL. Paradoxically, CTL responses were diminished in patients after 2xa0weeks of IL-2. We hypothesized that changes in the cytokine milieu may have contributed to this result. Experimental design: Serum samples were studied from 37 patients enrolled in two clinical trials of a melanoma peptide vaccine administered with or without low-dose IL-2 therapy. Twenty-two patients enrolled in the MEL36 trial received six weekly vaccinations with the four-peptide mixture and were randomized to receive subcutaneous IL-2 (3×106xa0IU/m2/day) daily for 6xa0weeks beginning either at week 1 (upfront group) or at week 4 (delayed group) of vaccine therapy. Fifteen patients on the MEL39 trial were treated with the same vaccine without concurrent IL-2 administration. Results: Circulating levels of IL-5 peaked 1xa0week after starting IL-2, followed 2xa0weeks later by a marked eosinophilia, correlating in magnitude with peak IL-5 serum levels. Levels of IFNγ, GM-CSF, IL-4, IL-10, and IL-12 had no observed relationship to IL-2 administration. At the time of the IL-5 serum peak, PBL responses to mitogen suggested a transient shift to Th2-dominance. Conclusions: Low-dose IL-2 appears to have induced a transient Th2-dominant secondary cytokine cascade at the time of vaccination, for which eosinophilia is a surrogate marker. For future vaccine therapies targeting cytotoxic T-cell responses, delaying IL-2 until after initiation of immune responses may be more effective.