Distribution and function of polycystin-2 in mouse retinal ganglion cells

The polycystin family of transient receptor potential (TRP) channels form Ca(2+) regulated cation channels with distinct subcellullar localizations and functions. As part of heteromultimeric channels and multi-protein complexes, polycystins control intracellular Ca(2+) signals and more generally the translation of extracellular signals and stimuli to intracellular responses. Polycystin-2 channels have been cloned from retina, but their distribution and function in retinal ganglion cells (RGCs) have not yet been established. In the present study, we determined cellular and subcellular localization as well as functional properties of polycystin-2 channels in RGCs. Polycystin-2 expression and distribution in RGCs was assessed by immunohistochemistry on vertical cryostat section of mouse retina as well as primary cultured mouse RGCs, using fluorescence microscopy. Biophysical and pharmacological properties of polycystin-2 channels isolated from primary cultured RGCs were determined using planar lipid bilayer electrophysiology. We detected polycystin-2 immunoreactivity both in the ganglion cell layer as well as in primary cultured RGCs. Subcellular analysis revealed strong cytosolic localization pattern of polycystin-2. Polycystin-2 channel current was Ca(2+) activated, had a maximum slope conductance of 114 pS, and could be blocked in a dose-dependent manner by increasing concentrations of Mg(2+). The cytosolic localization of polycystin-2 in RGCs is in accordance with its function as intracellular Ca(2+) release channel. We conclude that polycystin-2 forms functional channels in RGCs, of which biophysical and pharmacological properties are similar to polycystin-2 channels reported for other tissues and organisms. Our data suggest a potential role for polycystin-2 in RGC Ca(2+) signaling.

Marginal recurrence requiring salvage radiotherapy after stereotactic body radiotherapy for spinal metastases

INTRODUCTION

We sought to quantify and identify risk factors associated with margin recurrence (MR) requiring salvage radiotherapy after stereotactic body radiation therapy (SBRT) for spinal metastases.

METHODS

We retrospectively reviewed patients with spinal metastases who were treated with single-fraction SBRT between 2006 and 2009. Gross tumor was contoured, along with either the entire associated vertebral body(ies) or the posterior elements, and included in the planning target volume. No additional margins were used. MR was defined as recurrent tumor within one vertebral level above or below the treated lesion that required salvage radiotherapy. Only patients who presented for 3-month post-SBRT follow-up were included in the analysis. Fine and Gray competing risk regression models were generated to identify variables associated with higher risks of MR. MR was plotted using cumulative incidence analysis.

RESULTS

SBRT was delivered to 208 lesions in 149 patients. Median follow-up was 8.6 months, and median survival was 12.8 months. The median prescribed dose was 14 Gy (10-16 Gy). MR occurred in 26 (12.5%) treated lesions, at a median time of 7.7 months after SBRT. Patients with paraspinal disease at the time of SBRT (20.8% vs. 7.6% of patients; p = 0.02), and those treated with <16 Gy (16.3% vs. 6.3% of patients, p = 0.14) had higher rates of MR. Both variables were associated with significantly higher risk of MR on multivariate analysis.

CONCLUSION

SBRT for spinal metastases results in a low overall rate of MR. The presence of paraspinal disease at the time of SBRT and a dose of <16 Gy were associated with higher risks of MR.

Treatment outcomes for patients with glioblastoma multiforme and a low Karnofsky Performance Scale score on presentation to a tertiary care institution. Clinical article

OBJECT

The object of this study was to determine the benefit of surgery, radiation, and chemotherapy for patients with glioblastoma multiforme (GBM) and a low Karnofsky Performance Scale (KPS) score.

METHODS

The authors retrospectively evaluated the records of patients who underwent primary treatment for pathologically confirmed GBM and with a KPS score ≤ 50 on initial evaluation for radiation therapy at a tertiary care institution between 1977 and 2006. Seventy-four patients with a median age of 69 years (range 19-88 years) and a median KPS score of 50 (range 20-50) were retrospectively grouped into the Radiation Therapy Oncology Group (RTOG) recursive partitioning analysis (RPA) Classes IV (11 patients), V (15 patients), and VI (48 patients). Patients underwent biopsy (38 patients) or tumor resection (36 patients). Forty-seven patients received radiation. Nineteen patients also received chemotherapy (53% temozolomide), initiated concurrently (47%) or after radiotherapy.

RESULTS

The median survival overall was 2.3 months (range 0.2-48 months). Median survival stratified by RPA Classes IV, V, and VI was 6.6, 6.6, and 1.8 months, respectively (p < 0.001, log-rank test). Median survival for patients receiving radiation (5.2 months) was greater than that for patients who declined radiation (1.6 months, p < 0.001). Patients in RPA Class VI appeared to benefit from radiotherapy only when tumor resection was also performed. The median survival from treatment initiation was greater for patients receiving chemotherapy concomitantly with radiotherapy (9.8 months) as compared with radiotherapy alone (1.7 months, p = 0.002). Of 20 patients seen for follow-up in the clinic at a median of 48 days (range 24-196 days) following radiotherapy, 70% were noted to have an improvement in the KPS score of between 10 and 30 points from the baseline score. On multivariate analysis, only RPA class (p = 0.01), resection (HR = 0.37, p = 0.001), and radiation therapy (HR = 0.39, p = 0.02) were significant predictors of a decreased mortality rate.

CONCLUSIONS

Patients with a KPS score ≤ 50 appear to have increased survival and functional status following tumor resection and radiation. The extent of benefit from concomitant chemotherapy is unclear. Future studies may benefit from reporting that utilizes a prognostic classification system such as the RTOG RPA class, which has been shown to be effective at separating outcomes even in patients with low performance status. Patients with GBMs and low KPS scores need to be evaluated in prospective studies to identify the extent to which different therapies improve outcomes.

The role of adjuvant radiation therapy in the treatment of spinal myxopapillary ependymomas

Object

The goal in this study was to determine the role of radiation therapy (RT) in the treatment of spinal myxopapillary ependymomas (MPEs).

Methods

Thirty-seven patients with histologically verified spinal MPEs were reviewed. Kaplan-Meier analyses and Cox proportional hazard regression were used to determine what patient and treatment factors influenced overall survival (OS) and recurrence.

Results

At the time of initial diagnosis, the median age was 33 years and the Karnofsky Performance Scale score was 80. In 86.5% of cases, the most common presenting symptom was pain. All patients received surgery as their initial treatment. Nine patients also received RT along with surgery, with a median total dose of 50.2 Gy. The mean survival time was 12.2 years; however, only 4 of 37 patients had died at the time of this study. None of the patient or treatment parameters significantly correlated with OS. Sixteen patients (43.2%) were found to have a recurrence, with a median time to recurrence of 7.7 years. None of the patient or treatment parameters correlated with recurrence-free survival for an initial recurrence. The median time to the second recurrence (recurrence following therapy for initial recurrence) was 1.6 years. Use of RT as salvage therapy after initial recurrence significantly correlated with longer times to a second recurrence. The median recurrence-free survival time before the second recurrence was 9.6 years for those who received RT versus 1.1 years for those who did not receive RT (p = 0.0093). None of the other parameters significantly correlated with a second recurrence.

Conclusions

Radiation therapy may have a role as salvage therapy in delaying recurrences of spinal MPEs.

Abstract P5-14-04: Patterns of Locoregional Failure in Women with Invasive Breast Cancer Treated with Mastectomy and Tissue Expander/Implant Reconstruction

BACKGROUND: Breast reconstruction with a tissue expander/implant (TE/I) following mastectomy for invasive breast cancer poses unique challenges in detecting local recurrence and in the technical delivery of post-mastectomy radiotherapy (PMRT). For women identified as having high risk disease, PMRT lowers the risk of locoregional failure (LRF) and enhances long-term survival. The aim of this study was to evaluate the patterns of LRF in women who underwent mastectomy and implant reconstruction, with or without adjuvant PMRT.

METHODS: We performed a retrospective review of all patients undergoing mastectomy with TE/I reconstruction for non-metastatic invasive breast cancer from 2001-2006 at the Cleveland Clinic, after approval from the institutional review board. The presence and location of locoregional recurrence was noted. Kaplan-Meier curves were generated to estimate locoregional recurrence free survival (LRFS) and overall survival (OS) rates.

RESULTS: The study population consisted of 326 patients: 121 (37%) with pathologic stage I disease, 128 (39%) with stage II, 46 (14%) with stage III, and 31 (10%) who underwent neoadjuvant systemic therapy prior to mastectomy. The median number of lymph nodes dissected was 10 and the median follow-up was 5.5 years. The OS for all patients at 5 years was 92.4%. By stage, 5-year OS was 95.9% for stage I, 94.4% for stage II,87.2% for stage III, and 79.6% for those undergoing pre-operative systemic therapy. The LRFS at 5 years for all patients was 91.3%. The 5-year LRFS was 95.4% for stage I, 93.6% for stage II, 79.4% for stage III, and 87.4% for those who underwent pre-operative systemic therapy. 8% of all patients had a LRF. By lymph node status, node-negative patients (N0) had a LRF rate of 4.8% (9/189), those with 1-3 nodes positive (N1) had a LRF rate of 5.0% (4/80), those with 4-9 nodes positive (N2) had a LRF rate of 17.5% (7/40), and those with 10 or more nodes positive (N3) had a LRF rate of 50% (6/12).

The most common sites of LRF were cutaneous chest wall (8/26) and axilla (8/26), followed by the supraclavicular/cervical nodes (5/26) and chest wall with muscle involvement (3/26). The remaining 2/26 failed at a combination of the above sites.

21.2% of the total population (69/326) underwent PMRT to the chest wall and regional nodes. By nodal status, including those who received neoadjuvant systemic therapy, 7.4% of women with zero nodes positive underwent radiation, followed by 18.8% with 1-3 nodes positive, and 76.9% with 4 or more nodes positive.

CONCLUSIONS: The crude rate of LRF in this large institutional series is similar to what has been previously reported in the literature. In our population, LRF in the superficial chest wall occurred at the same rate as the axillary nodes, which was followed in frequency by the supraclavicular/cervical nodes. Nearly 1/4 of women with 4 or more positive axillary nodes underwent no adjuvant radiation therapy following mastectomy, despite being a population of women known to derive benefit from PMRT. Further investigation is required to determine whether the presence of a TE/I reconstruction alters decision-making for adjuvant local therapy and/or impacts the technical delivery of PMRT.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-14-04.

Demonstration of Laccase in the White Rot Basidiomycete Phanerochaete chrysosporium BKM-F1767

It has been widely reported that the white rot basidiomycete Phanerochaete chrysosporium, unlike most other white rot fungi, does not produce laccase, an enzyme implicated in lignin biodegradation. Our results showed that P. chrysosporium BKM-F1767 produces extracellular laccase in a defined culture medium containing cellulose (10 g/liter) and either 2.4 or 24 mM ammonium tartrate. Laccase activity was demonstrated in the concentrated extracellular culture fluids of this organism as determined by a laccase plate assay as well as a spectrophotometric assay with ABTS [2,2(prm1)-azinobis(3-ethylbenzathiazoline-6-sulfonic acid)] as the substrate. Laccase activity was observed even after addition of excess catalase to the extracellular culture fluid to destroy the endogenously produced hydrogen peroxide, indicating that the observed activity is not due to a peroxidase. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by activity staining with ABTS revealed the presence of a laccase band with an estimated M(infr) of 46,500.

Ultrastructural Localization of Hydrogen Peroxide Production in Ligninolytic Phanerochaete chrysosporium Cells

Previous studies have shown that the hydroxyl radical derived from hydrogen peroxide (H(2)O(2)) is involved in lignin degradation by Phanerochaete chrysosporium. In the present study, the ultrastructural sites of H(2)O(2) production in ligninolytic cells of P. chrysosporium were demonstrated by cytochemically staining cells with 3,3'-diaminobenzidine (DAB). Hydrogen peroxide production, as evidenced by the presence of oxidized DAB deposits, appeared to be localized in the periplasmic space of cells from ligninolytic cultures grown for 14 days in nitrogen-limited medium. When identical cells were treated with DAB in the presence of aminotriazole, periplasmic deposits of oxidized DAB were not observed, suggesting that the deposits resulted from the H(2)O(2)-dependent peroxidatic oxidation of DAB by catalase. Cells from cultures grown for 3 or 6 days in nitrogen-limited medium or for 14 days in nitrogen-sufficient medium had little ligninolytic activity and low specific activity for H(2)O(2) production and did not contain periplasmic oxidized DAB deposits. The results suggest that in cultures grown in nitrogen-limited medium, there is a positive correlation between the occurrence of oxidized DAB deposits, the specific activity for H(2)O(2) production in cell extracts, and ligninolytic activity.

Isolation of saprophytic basidiomycetes from soil

A method with the combined advantages of soil particle washing, selective inhibitors, and an indicator substrate was developed to isolate saprophytic basidiomycetes from soil. Organic particles were washed from soil and plated on a medium containing lignin, guaiacol, and benomyl, which reduced mold growth and allowed detection of basidiomycetes producing laccase or peroxidase. The 64 soil samples yielded 67 basidiomycete isolates, representing 51 groups on the basis of morphology and physiology. This method should facilitate investigations into the biodiversity of soil basidiomycetes and yield organisms that are useful in bioremediation of soils contaminated with pesticides or other recalcitrant aromatic compounds.

PSA bounce and biochemical failure after brachytherapy for prostate cancer: a study of 820 patients with a minimum of 3 years of follow-up

PURPOSE

To determine clinical or dosimetric factors associated with a prostate-specific antigen (PSA) bounce, as well as an association between a PSA bounce and biochemical relapse-free survival (bRFS), in patients treated with iodine-125 brachytherapy.

METHODS AND MATERIALS

A variety of clinical and treatment factors were examined in 820 patients who had a minimum of 3 years of PSA follow-up with T1-T2cN0M0 prostate cancer. Four different PSA threshold values were used for defining a PSA bounce: a PSA rise of ≥ 0.2, ≥ 0.4, ≥ 0.6, and ≥ 0.8 ng/mL.

RESULTS

A PSA bounce of ≥ 0.2, ≥ 0.4, ≥ 0.6, and ≥ 0.8 ng/mL was noted in 247 patients (30.1%), 161 (19.6%), 105 (12.8%), and 78 (9.5%), respectively. The median time to the first PSA rise was 17.4, 16.25, 16.23, and 15.71 months, respectively, vs. 34.35 months for a biochemical failure (p < 0.0001). A PSA rise of ≥ 0.2 ng/mL was the only definition for which there was a significant difference in bRFS between bounce and non-bounce patients. The 5-year bRFS rate of patients having a PSA bounce of ≥0.2 was 97.7% vs. 91% for those who did not have a PSA bounce (p = 0.0011). On univariate analysis for biochemical failure, age, risk group, and PSAs per year had a statistically significant correlation with PSA bounce of ≥ 0.2 ng/mL. On multivariate analysis, age and PSAs per year remained statistically significant (p < 0.0001 and p = 0.0456, respectively).

CONCLUSIONS

A bounce definition of a rise ≥ 0.2 ng/mL is a reliable definition among several other definitions. The time to first PSA rise is the most valuable factor for distinguishing between a bounce and biochemical failure.

Association of body mass index with prostate cancer biochemical failure

PURPOSE

The association between obesity and biochemical failure measured by prostate specific antigen after prostate cancer treatment is controversial. We determined whether there is an association between body mass index and biochemical failure in men treated for low and intermediate risk prostate cancer with various treatment modalities.

MATERIALS AND METHODS

We performed a cohort study in 2,687 patients who underwent treatment for low and intermediate risk prostate adenocarcinoma as described by National Comprehensive Cancer Network guidelines at Cleveland Clinic between January 1996 and December 2005. Univariate and multivariate analyses were done to determine the effect of multiple patient characteristics on biochemical failure.

RESULTS

There were 319 biochemical failures (11.9%). Body mass index as a continuous variable was significantly associated with biochemical failure on univariate analysis (HR 1.030, p = 0.02). There was a significant association with biochemical failure when comparing normal vs overweight and normal vs obese men but not overweight vs obese men. On multivariate analysis body mass index as a continuous or a categorical variable was not significantly associated with biochemical failure. Multivariate analysis revealed certain variables significantly associated with biochemical failure, including black race, greater initial prostate specific antigen, Gleason score 7, treatment type and more frequent prostate specific antigen screening.

CONCLUSIONS

We found a significant association between body mass index and biochemical failure on univariate analysis that did not hold true on multivariate analysis. Black race was associated with biochemical failure on multivariate analysis. The reason for this is unclear. Future studies should further characterize the relationship between race and biochemical failure.

Maximum standardized uptake value from staging FDG-PET/CT does not predict treatment outcome for early-stage non-small-cell lung cancer treated with stereotactic body radiotherapy

PURPOSE

To perform a retrospective review to determine whether maximum standardized uptake values (SUV(max)) from staging 2-deoxy-2- [(18)F] fluoro-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) studies are associated with outcomes for early-stage non-small-cell lung cancer (NSCLC) treated with stereotactic body radiotherapy (SBRT).

METHODS AND MATERIALS

Seventy-two medically inoperable patients were treated between October 17, 2003 and August 17, 2007 with SBRT for T1-2N0M0 NSCLC. SBRT was administered as 60 Gy in 3 fractions, 50 Gy in 5 fractions, or 50 Gy in 10 fractions using abdominal compression and image-guided SBRT. Cox proportional hazards regression was performed to determine whether PET SUV(max) and other variables influenced outcomes: mediastinal failure (MF), distant metastases (DM), and overall survival (OS).

RESULTS

Biopsy was feasible in 49 patients (68.1%). Forty-nine patients had T1N0 disease, and 23 had T2N0 disease. Median SUV(max) was 6.55 (range, 1.5-21). Median follow-up was 16.9 months (range, 0.1-37.9 months). There were 3 local failures, 8 MF, 19 DM, and 30 deaths. Two-year local control, MF, DM, and OS rates were 94.0%, 10.4%, 30.1%, and 61.3%, respectively. In univariate analysis, PET/CT SUV(max), defined either as a continuous or dichotomous variable, did not predict for MF, DM, or OS. On multivariable analysis, the only predictors for overall survival were T1 stage (hazard ratio = 0.331 [95% confidence interval, 0.156-0.701], p = 0.0039) and smoking pack-year history (hazard ratio = 1.015 [95% confidence interval, 1.004-1.026], p = 0.0084).

CONCLUSIONS

Pretreatment PET SUV(max) did not predict for MF, DM, or OS in patients treated with SBRT for early-stage NSCLC.

Five year biochemical recurrence free survival for intermediate risk prostate cancer after radical prostatectomy, external beam radiation therapy or permanent seed implantation

OBJECTIVE

To compare biochemical recurrence-free survival (bRFS) for patients with intermediate-risk prostate cancer treated by retropubic radical prostatectomy (RRP), laparoscopic radical prostatectomy (LRP), external beam radiation therapy (RT), or permanent seed implantation (PI).

METHODS

Patients treated for intermediate-risk prostate cancer per National Comprehensive Cancer Network guidelines from 1996 to 2005 were studied. Variables potentially affecting bRFS were examined using univariate and multivariate Cox regression analysis. Five-year bRFS rates were calculated by actuarial methods; bRFS was calculated using Kaplan-Meier analysis. Nadir +2 definition of biochemical failure was used for RT and PI patients; a PSA ≥ 0.4 ng/mL was used for radical prostatectomy (RP) patients. Time to initiation of salvage therapy was compared for each treatment group using the Kruskal-Wallis test.

RESULTS

Nine-hundred seventy-nine patients were analyzed with a median follow-up of 65 months. Five years bRFS rate was 82.8% for all patients (89.5% PI, 85.7% RT, 79.9% RRP, and 60.2% LRP). Patients treated by LRP had significantly worse bRFS than RT (P < .0001), PI (P < .0001), or RRP patients (P = .0038). Treatment modality (P < .0001) and average number of PSA tests per year (P < .0001) were the only independent predictors of bRFS on multivariate analysis. Median time to initiation of salvage therapy from time of treatment was 28.6 months for all patients (26.1 RP, 21.0 LRP, 47.4 PI, 47.8 RT; P < .0001).

CONCLUSIONS

Patients with intermediate-risk prostate cancer choosing PI, RT, or RRP appear to have improved 5-year bRFS and delayed salvage therapy compared with LRP.

Stereotactic radiosurgery for single brainstem metastases: the cleveland clinic experience

PURPOSE

To assess the imaging and clinical outcomes of patients with single brainstem metastases treated with stereotactic radiosurgery (SRS).

MATERIALS AND METHODS

We retrospectively reviewed the data from patients with single brainstem metastases treated with SRS. Locoregional control and survival were calculated using the Kaplan-Meier method. Prognostic factors were assessed using a Cox proportional hazards model.

RESULTS

Between 1997 and 2007, 43 patients with single brainstem metastases were treated with SRS. The median age at treatment was 59 years, the median Karnofsky performance status was 80, and the median follow-up was 5.3 months. The median dose was 15 Gy (range, 9.6-24), and the median conformality and heterogeneity index was 1.7 and 1.9, respectively. The median survival was 5.8 months from the procedure date. Of the 33 patient with post-treatment imaging available, a complete radiographic response was achieved in 2 (4.7%), a partial response in 8 (18.6%), and stable disease in 23 (53.5%). The 1-year actuarial rate of local control, distant brain control, and overall survival was 85%, 38.3%, and 31.5%, respectively. Of the 43 patients, 8 (19%) died within 2 months of undergoing SRS, and 15 (36%) died within 3 months. On multivariate analysis, greater performance status (hazard ratio [HR], 0.95, p = .004), score index for radiosurgery (HR, 0.7; p = .004), graded prognostic assessment score (HR, 0.48; p = .003), and smaller tumor volume (HR, 1.23, p = .002) were associated with improved survival. No Grade 3 or 4 toxicities were observed.

CONCLUSION

The results of our study have shown that SRS is a safe and effective local therapy for patients with brainstem metastases.

Gender, race, and survival: a study in non-small-cell lung cancer brain metastases patients utilizing the radiation therapy oncology group recursive partitioning analysis classification

PURPOSE

To explore whether gender and race influence survival in non-small-cell lung cancer (NSCLC) in patients with brain metastases, using our large single-institution brain tumor database and the Radiation Therapy Oncology Group recursive partitioning analysis (RPA) brain metastases classification.

METHODS AND MATERIALS

A retrospective review of a single-institution brain metastasis database for the interval January 1982 to September 2004 yielded 835 NSCLC patients with brain metastases for analysis. Patient subsets based on combinations of gender, race, and RPA class were then analyzed for survival differences.

RESULTS

Median follow-up was 5.4 months (range, 0-122.9 months). There were 485 male patients (M) (58.4%) and 346 female patients (F) (41.6%). Of the 828 evaluable patients (99%), 143 (17%) were black/African American (B) and 685 (83%) were white/Caucasian (W). Median survival time (MST) from time of brain metastasis diagnosis for all patients was 5.8 months. Median survival time by gender (F vs. M) and race (W vs. B) was 6.3 months vs. 5.5 months (p = 0.013) and 6.0 months vs. 5.2 months (p = 0.08), respectively. For patients stratified by RPA class, gender, and race, MST significantly favored BFs over BMs in Class II: 11.2 months vs. 4.6 months (p = 0.021). On multivariable analysis, significant variables were gender (p = 0.041, relative risk [RR] 0.83) and RPA class (p < 0.0001, RR 0.28 for I vs. III; p < 0.0001, RR 0.51 for II vs. III) but not race.

CONCLUSIONS

Gender significantly influences NSCLC brain metastasis survival. Race trended to significance in overall survival but was not significant on multivariable analysis. Multivariable analysis identified gender and RPA classification as significant variables with respect to survival.