Differential regulation of androgen receptor by PIM-1 kinases via phosphorylation-dependent recruitment of distinct ubiquitin E3 ligases.

Androgen receptor (AR) plays a pivotal role in prostate cancer. Regulation of AR transcriptional activity by post-translational modifications, such as phosphorylation by multiple kinases, is well documented. Here, we report that two PIM-1 kinase isoforms which are up-regulated during prostate cancer progression, namely PIM-1S and PIM-1L, modulate AR stability and transcriptional activity through differentially phosphorylating AR at serine 213 (Ser-213) and threonine 850 (Thr-850). Although both kinases are capable of interacting with and phosphorylating AR at Ser-213, only PIM-1L could phosphorylate Thr-850. We also showed that PIM-1S induced Ser-213 phosphorylation destabilizes AR by recruiting the ubiquitin E3 ligase Mdm2 and promotes AR degradation in a cell cycle-dependent manner, while PIM-1L-induced Thr-850 phosphorylation stabilizes AR by recruiting the ubiquitin E3 ligase RNF6 and promotes AR-mediated transcription under low-androgen conditions. Furthermore, both PIM-1 isoforms could promote prostate cancer cell growth under low-androgen conditions. Our data suggest that these kinases regulate AR stability and transcriptional activity through recruitment of different functional partners in a phosphorylation-dependent manner. As AR turnover has been previously shown to be critical for cell cycle progression in prostate cancer cells, PIM-1 kinase isoforms may promote prostate cancer cell growth, at least in part, through modulating AR activity via distinct mechanisms.

Novel membrane-associated androgen receptor splice variant potentiates proliferative and survival responses in prostate cancer cells.

Progression from the androgen-sensitive to androgen-insensitive (or castration-resistant) stage is the major obstacle for sustained effectiveness of hormonal therapy for prostate cancer. The androgen receptor (AR) and its splice variants play important roles in regulating the transcription program essential for castration resistance. Here, we report the identification of a novel AR splice variant, designated as AR8, which is up-regulated in castration-resistant prostate cancer cells. AR8 is structurally different from other known AR splice variants because it lacks a DNA binding domain and therefore, unlikely functions as a transcription factor on its own. Immunofluorescence staining revealed that AR8 was primarily localized on the plasma membrane, possibly through palmitoylation of two cysteine residues within its unique C-terminal sequence. Mutation of these putative palmitoylation sites in AR8 led to loss of its plasma membrane localization. In addition, we demonstrated that overexpression of AR8 in prostate cancer cells promoted association of Src and AR with the EGF receptor in response to EGF treatment and enhanced tyrosine phosphorylation of AR. Conversely, specific knockdown of AR8 expression in prostate cancer cells compromised EGF-induced Src activation and AR phosphorylation. This effect was accompanied with attenuation of proliferation and increased apoptosis in prostate cancer cells cultured in androgen-depleted medium. We also showed that AR8 was required for optimal transcriptional activity of AR in response to treatment of both androgen and EGF. Taken together, our results demonstrate that the membrane-associated AR8 isoform may contribute to castration resistance by potentiating AR-mediated proliferative and survival responses to hormones and growth factors.

SRC Kinase-Mediated Tyrosine Phosphorylation of TUBB3 Regulates Its Stability and Mitotic Spindle Dynamics in Prostate Cancer Cells.

Tubulin is an integral part of the cytoskeleton and plays a pivotal role in cellular signaling, maintenance, and division. ß-tubulin is also the molecular target for taxane compounds such as docetaxel (DTX) and cabazitaxel (CTX), both first-line treatments for several solid cancers. Increased expression of Class III ß-tubulin (TUBB3), a primarily neural isoform of ß-tubulin, correlates with taxane resistance and poor prognosis. Although tyrosine kinase c-Src has been implicated to phosphorylate ß-tubulins during both hematopoietic and neural differentiation, the mechanisms by which Src modulates tubulins functions are still poorly understood. Here, we report, for the first time, that TUBB3 is phosphorylated at Tyrosine 340 (Y340) by c-SRC in prostate cancer cells. We also showed that Y340 phosphorylation regulates TUBB3 protein stability and subcellular localization. Furthermore, we demonstrated that inhibition of SRC kinase activity compromises spindle stability in mitotic cells, at least partly due to the lack of TUBB3 Y340 phosphorylation. Given the importance of TUBB3 as a clinical biomarker of poor prognosis and drug resistance, characterization of TUBB3 posttranslational regulation could potentially serve as new biomarkers for disease recurrence and/or treatment failure.

Shoulder pain: a comparison of wheelchair athletes and nonathletic wheelchair users.

PURPOSE: The purpose of this study was to directly compare the onset and prevalence of shoulder pain in athletic and nonathletic wheelchair users. METHODS: A questionnaire was distributed to athletic and nonathletic wheelchair-dependent populations. This inquired about presence and duration of shoulder pain, age of subject, level of injury, duration of time since injury, wheelchair use, involvement in sports, and training habits. A total of 257 subjects were involved in the study. RESULTS: The odds of having shoulder pain were twice as high among nonathletes as they were among athletes. This finding represents a significant difference over and above age differences, differences in years spent in a wheelchair, and differences in level of spinal cord injury. Athletes also have an average of 12 yr free of shoulder pain after becoming wheelchair bound, whereas nonathletes have only 8 yr. CONCLUSION: Promotion of active exercise for wheelchair users is encouraged to decrease shoulder pain, resulting in more functional, pain-free years.

Tyrosine kinase ETK/BMX is up-regulated in bladder cancer and predicts poor prognosis in patients with cystectomy.

Deregulation of the non-receptor tyrosine kinase ETK/BMX has been reported in several solid tumors. In this report, we demonstrated that ETK expression is progressively increased during bladder cancer progression. We found that down-regulation of ETK in bladder cancer cells attenuated STAT3 and AKT activity whereas exogenous overexpression of ETK had opposite effects, suggesting that deregulation of ETK may attribute to the elevated activity of STAT3 and AKT frequently detected in bladder cancer. The survival, migration and invasion of bladder cancer cells were significantly compromised when ETK expression was knocked down by a specific shRNA. In addition, we showed that ETK localizes to mitochondria in bladder cancer cells through interacting with Bcl-XL and regulating ROS production and drug sensitivity. Therefore, ETK may play an important role in regulating survival, migration and invasion by modulating multiple signaling pathways in bladder cancer cells. Immunohistochemistry analysis on tissue microarrays containing 619 human bladder tissue samples shows that ETK is significantly upregulated during bladder cancer development and progression and ETK expression level predicts the survival rate of patients with cystectomy. Taken together, our results suggest that ETK may potentially serve as a new drug target for bladder cancer treatment as well as a biomarker which could be used to identify patients with higher mortality risk, who may be benefited from therapeutics targeting ETK activity.

Effect of obesity on inpatient rehabilitation outcomes following total knee arthroplasty.

OBJECTIVES: To examine obesity effects on outcomes following inpatient rehabilitation in patients following primary total knee arthroplasty or revision total knee arthroplasty. DESIGN: Retrospective, comparative study. SETTING: Fifty-bed, university-affiliated rehabilitation hospital. PATIENTS: Obese (N = 139; body mass index >30 kg/m(2)) and non-obese (N = 146; body mass indexB <30 kg/m(2)) total knee arthroplasty patients. Participants were further stratified based on total knee arthroplasty type, primary and revision for a total of four groups. INTERVENTION: Interdisciplinary inpatient rehabilitation. MAIN MEASURES: Range of motion, length of stay, Functional Independence Measure (FIM) scores, FIM efficiency scores, total and daily hospital charges, and discharge disposition location. RESULTS: Range of motion and FIM scores improved from admission to discharge in both obese and non-obese patients regardless of total knee arthroplasty type. FIM efficiency was lower in revision than primary total knee arthroplasty (2.8 versus 3.6 patients/day; P < 0.005) but not different between obese and non-obese groups. Total hospital charges were lower for the primary than for the revision patients (P < 0.05), but were directly related with body mass index (r = 0.140, P < 0.05). Discharge disposition locations were not different among groups. CONCLUSION: Rehabilitation teams can expect comparable gains between obese and non-obese patients following total knee arthroplasty, but at a greater expense.

Outcomes after inpatient rehabilitation of primary and revision total hip arthroplasty.

OBJECTIVE: To compare the outcomes of patients who have gone to inpatient rehabilitation after primary total hip arthroplasty (THA) and revision THA. DESIGN: Retrospective, comparative study. SETTING: Fifty-bed freestanding, university-affiliated rehabilitation hospital. PARTICIPANTS: Two hundred fifty-five male and female primary THA patients and 147 male and female revision THA patients. INTERVENTION: Interdisciplinary inpatient rehabilitation. MAIN OUTCOME MEASURES: Length of stay (LOS), FIM instrument score and FIM motor score components, hospital charges, and discharge disposition location. RESULTS: FIM scores improved from admission to discharge by 29.7 and 27.9 points for the primary THA and revision THA groups, respectively (P<.05). LOS was shorter for primary THA patients compared with revision THA patients (10.0d vs 11.5d, P<.05). FIM efficiency (DeltaFIM/LOS) was greater for primary THA compared with revision THA (3.4 and 2.7 points/day, P<.05). Total rehabilitation hospital charges were 11,421 US dollars and 13,707 US dollars for the primary and revision THA groups, respectively, with the mechanical and infection revision THAs incurring the greatest charges (14,596 US dollars and 15,386 US dollars, respectively; P<.001). Compared with primary THA, revision THA patients were twice as likely to be discharged to locations other than home. CONCLUSIONS: FIM score improvement was lower and LOS and hospital charges were greater in revision THA than in primary THA after rehabilitation. Infection revision THA patients gained less functional independence and were discharged home less often than mechanical or pain revision THA patients; finally, infection and mechanical revision THA accrued the highest hospital charges.

A preliminary examination of the CMS eligibility criteria in total-joint arthroplasty.

OBJECTIVE: To analyze inpatient rehabilitation outcomes in total-knee arthroplasty (TKA) and total-hip arthroplasty (THA) patients using the 2004 Medicare 75% rule criteria. DESIGN: This retrospective study compared outcomes in unilateral TKA (UTKA), bilateral TKA (BTKA), and THA after interdisciplinary inpatient rehabilitation (n = 867). Patients were separated into three comparison pairs: 1) UTKA or BTKA, 2) age <85 yrs or > or =85 yrs, and 3) body mass index (BMI) <50 or > or =50 kg/m. Length of stay (LOS), functional independence measure (FIM) scores (total, motor, and cognitive), hospital charges, FIM efficiency, and discharge disposition were analyzed. RESULTS: BTKA improved total FIM score more than UTKA (43 vs. 38%; P = 0.039). TKA with BMI > or =50 kg/m had similar admission and discharge FIM motor scores compared with BMI <50 kg/m (P > 0.05). TKA patients > or =85 yrs had lower admission FIM scores, longer LOS (11.3 vs. 9.4 days), and 22% higher total charges than TKA patients younger than 85 yrs (P = 0.042). THA patients > or =85 yrs had 6-10% lower total FIM, FIM motor, and FIM cognition scores and were discharged to home less frequently than younger patients (P < 0.05). Total and daily charges were 21-162% higher in THA patients with BMIs > or =50 kg/m than in THA patients with BMIs <50 kg/m (P < 0.045). CONCLUSION: All patients made functional gains during rehabilitation. However, the most costly and lengthy rehabilitation occurred in TKA patients > or =85 yrs and THA patients with BMI > or =50 kg/m.

Outcomes in total knee arthroplasty patients after inpatient rehabilitation: influence of age and gender.

OBJECTIVES: To examine age and gender effects on outcomes after inpatient rehabilitation in primary total knee arthroplasty (TKA) and revision TKA patients. DESIGN: This retrospective, comparative study was conducted in a 50-bed, university-affiliated rehabilitation hospital. Patients included primary TKA patients (n = 286) and revision TKA patients (n = 138) placed into one of three age brackets: <60 yrs, 60-70 yrs, or >70 yrs. Measurements included length of stay (LOS), FIM scores, hospital charges, and discharge disposition location. RESULTS: FIM scores improved from admission to discharge in both primary and revision patients (P = 0.015). LOS was shorter in primary than revision patients (8.3 vs. 10.4 days, P = 0.001), and the LOS was longest in patients >70 yrs compared with those <60 or 60-70 yrs (10.6 vs. 8.7 and 8.8 days, respectively; P = 0.004). FIM efficiency was greater in primary than in revision TKA patients (3.68 vs. 2.77 points/day, P = 0.001), and greater for men than women in each age bracket regardless of TKA type (3.68 vs. 2.78 points/day, P = 0.001). Total hospital charges were lower for men than women for both TKA types ($9,656 +/- 823 vs. $11,544 +/- 1,359; P = 0.015), and were highest in patients >70 yrs of age (P = 0.015). CONCLUSIONS: Primary and revision TKA patients make improvements in functional independence during inpatient rehabilitation. Although FIM gains were similar among age and gender groupings, FIM efficiency is lowest in women. Despite similar daily hospital costs among the groups, slower progress with functional gains (decreased FIM efficiency) increases the LOS and total hospital charges, especially in older women.

Inpatient rehabilitation outcomes in primary and revision total knee arthroplasty patients.

UNLABELLED: Inpatient rehabilitation is an effective means of improving physical function and independence following total knee arthroplasty (TKA). Revision TKA (TKAR) is becoming increasingly more prevalent and it is unclear if revision TKAR patients attain similar improvements following inpatient rehabilitation compared to primary TKA (TKAP) patients. This investigation compared functional outcomes following interdisciplinary inpatient rehabilitation in 286 TKAP and 138 TKAR consecutive male and female patients. Functional Independence Measure (FIM) scores improved from admission to discharge for the TKAP (81.6 to 110.5) and TKAR (74.4 to 101.4) groups (p = 0.015). TKAP patients had shorter length of stay (LOS) compared to TKAR (9.2 and 11.3). FIM efficiency (FIM/LOS) was greater for the TKAP compared to TKAR (3.6 and 2.6). Total hospital charges were 11,399 dollars and 13,407 dollars for the TKAP and TKAR groups, respectively. TKAP patients were more likely to be discharged home compared to the TKAR patients (97.6 vs. 78.3%). Both TKAP and TKAR patients demonstrate gains in FIM scores during inpatient rehabilitation. However, the amount of FIM efficiency is lower, and LOS and hospital charges are greater when comparing TKAR and TKAP. In addition, discharge disposition may be influenced by the type of TKA, primary and revision. LEVEL OF EVIDENCE: Prognostic study, level II-1 (retrospective study). See Guidelines for Authors for a complete description of levels of evidence.

Sex and age effects on outcomes of total hip arthroplasty after inpatient rehabilitation.

OBJECTIVE: To retrospectively examine the effects of sex and age on the inpatient rehabilitation outcomes of patients after total hip arthroplasty (THA). DESIGN: Exploratory, retrospective study. SETTING: A university-affiliated rehabilitation hospital. PARTICIPANTS: Male and female THA patients (N=332) were stratified into age brackets (<65y, 65-84y, >or=85y). All patients completed interdisciplinary inpatient rehabilitation. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Length of stay (LOS), FIM instrument scores, FIM efficiency (FIM/LOS), hospital costs, and discharge disposition location were collected by chart review. RESULTS: Regardless of age, women had lower FIM scores at admission and discharge than men (P<.05). FIM efficiency was 22% to 53% lower for women in primary THA and 16% to 85% lower in revision THA than men (P=.001). Women accrued higher total hospital charges than men (13,099 dollars vs 11,141 dollars; P<.05), and were discharged home less frequently than men (84.4% vs 90.9%; P<.05). Admission FIM scores were 10.6% and 8.9% lower and discharge FIM scores were 7.3% and 9.2% lower in patients 85 years or older than those less than 65 or 65 to 84 years (P<.01). FIM efficiency was 25% to 38% higher in patients less than 85 years than those 85 years and older (P=.015), and 37% higher in men than women (P=.001). Patients 85 years and older were discharged less frequently to home than patients less than 85 years (P<.05). CONCLUSIONS: All patients made functional improvement after inpatient rehabilitation, but women and patients 85 years and older had longer LOS and lower FIM efficiency, incurred greater hospital charges, and were less likely to be discharged to home than men and younger counterparts.