CBAP regulates the function of Akt-associated TSC protein complexes to modulate mTORC1 signaling

The Akt-Rheb-mTORC1 pathway plays a crucial role in regulating cell growth, but the mechanisms underlying the activation of Rheb-mTORC1 by Akt remain unclear. In our previous study, we found that CBAP was highly expressed in human T-ALL cells and primary tumors, and its deficiency led to reduced phosphorylation of TSC2/S6K1 signaling proteins as well as impaired cell proliferation and leukemogenicity. We also demonstrated that CBAP was required for Akt-mediated TSC2 phosphorylation in vitro. In response to insulin, CBAP was also necessary for the phosphorylation of TSC2/S6K1 and the dissociation of TSC2 from the lysosomal membrane. Here we report that CBAP interacts with AKT and TSC2, and knockout of CBAP or serum starvation leads to an increase in TSC1 in the Akt/TSC2 immunoprecipitation complexes. Lysosomal-anchored CBAP was found to override serum starvation and promote S6K1 and 4EBP1 phosphorylation and c-Myc expression in a TSC2-dependent manner. Additionally, recombinant CBAP inhibited the GAP activity of TSC2 complexes in vitro, leading to increased Rheb-GTP loading, likely due to the competition between TSC1 and CBAP for binding to the HBD domain of TSC2. Overexpression of the N26 region of CBAP, which is crucial for binding to TSC2, resulted in a decrease in mTORC1 signaling and an increase in TSC1 association with the TSC2/AKT complex, ultimately leading to increased GAP activity toward Rheb and impaired cell proliferation. Thus, we propose that CBAP can modulate the stability of TSC1-TSC2 as well as promote the translocation of TSC1/TSC2 complexes away from lysosomes to regulate Rheb-mTORC1 signaling.

A Novel Allogeneic Rituximab-Conjugated Gamma Delta T Cell Therapy for the Treatment of Relapsed/Refractory B-Cell Lymphoma

Chimeric antigen receptor T cell (CAR-T) therapy has been applied in the treatment of B-cell lymphoma; however, CAR-T manufacturing requires virus- or non-virus-based genetic modification, which causes high manufacturing costs and potential safety concerns. Antibody-cell conjugation (ACC) technology, which originated from bio-orthogonal click chemistry, provides an efficient approach for arming immune cells with cancer-targeting antibodies without genetic modification. Here, we applied ACC technology in Vγ9Vδ2 T (γδ2 T) cells to generate a novel off-the-shelf CD20-targeting cell therapy ACE1831 (rituximab-conjugated γδ2 T cells) against relapsed/refractory B-cell lymphoma. ACE1831 exhibited superior cytotoxicity against B-cell lymphoma cells and rituximab-resistant cells compared to γδ2 T cells without rituximab conjugation. The in vivo xenograft study demonstrated that ACE1831 treatment strongly suppressed the aggressive proliferation of B-cell lymphoma and prolonged the survival of tumor-bearing mice with no observed toxicity. Mass spectrometry analysis indicated that cell activation receptors including the TCR complex, integrins and cytokine receptors were conjugated with rituximab. Intriguingly, the antigen recognition of the ACC-linked antibody/receptor complex stimulated NFAT activation and contributed to ACE1831-mediated cytotoxicity against CD20-expressing cancer cells. This study elucidates the role of the ACC-linked antibody/receptor complex in cytotoxicity and supports the potential of ACE1831 as an off-the-shelf γδ2 cell therapy against relapsed/refractory B-cell lymphoma.

Abstract 3464: CBAP: A novel rheostat molecule for regulation of TSC GAP activity and mTORC1 signaling in cancer cells

The PI3K-mTOR signaling pathway is one of the most frequently dysregulated signaling cascades in cancer. Understanding the molecular wiring of the PI3K-mTOR signaling network and its activation in cancer will improve our understanding of their contribution to cancer pathology and provide novel therapeutic strategies by targeting this network. Our previous works demonstrated that Common receptor Beta chain Associated Protein (CBAP) is required for Jurkat cell leukemogenesis and regulates Akt-dependent TSC2 phosphorylation and lysosomal dissociation of TSC complexes, and in turn enhances mTORC1 signalling and expression of c-MYC and HIF-1a in Jurkat T-ALL leukemic cells. In this report, we tackle the question how TSC/Rheb/mTORC1 pathway is regulated by CBAP via cell-based functional assay, immunoprecipitation and in vitro GTPase assay. Our data revealed that CBAP interacted with TSC2 via tuberin-binding domain and could compete for TSC2 binding with TSC1 and suppressed the GTPase activation activity of TSC1/2 complexes. Akt could also associate with TSC2 complexes and CBAP in both Jurkat and CBAP-knockout Jurkat cells, except that TSC1 could be detected within the complexes only in the absence of CBAP. Moreover, the Rheb-GAP activity of this Akt-associated TSC2 complexes was sensitive to the presence of CBAP and TSC1/2 GAP activity was strongly suppressed by recombinant CBAP proteins in the in vitro reconstituted assay. Finally, a peptide domain of CBAP interacting with TSC2 was mapped and disruption of CBAP-TSC2 interaction by overexpressing this peptide inhibits the Akt/Rheb signal axis and suppresses leukemia cell growth. In summary, our data revealed an important role of the interaction between CBAP and TSC2 proteins in promoting Rheb/mTORC1 signaling activity, and suggested a crucial role of overexpression of CBAP protein in tumor cell proliferation.

Citation Format: Jong-Young J. Yen, Yun-Jung Chiang, Wei-Ting Liao, Shih-Hao Wang, Hsin-Fang Yang-Yen. CBAP: A novel rheostat molecule for regulation of TSC GAP activity and mTORC1 signaling in cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3464.

CBAP modulates Akt-dependent TSC2 phosphorylation to promote Rheb-mTORC1 signaling and growth of T-cell acute lymphoblastic leukemia

High-frequency relapse remains a clinical hurdle for complete remission of T-cell acute lymphoblastic leukemia (T-ALL) patients, with heterogeneous dysregulated signaling profiles—including of Raf-MEK-ERK and Akt-mTORC1-S6K signaling pathways—recently being implicated in disease outcomes. Here we report that GM-CSF/IL-3/IL-5 receptor common β-chain-associated protein (CBAP) is highly expressed in human T-ALL cell lines and many primary tumor tissues and is required to bolster leukemia cell proliferation in tissue culture and for in vivo leukemogenesis in a xenograft mouse model. Downregulation of CBAP markedly restrains expansion of leukemia cells and alleviates disease aggravation of leukemic mice. Transcriptomic profiling and molecular biological analyses suggest that CBAP acts upstream of Ras and Rac1, and functions as a modulator of both Raf-MEK–ERK and Akt-mTORC1 signaling pathways to control leukemia cell growth. Specifically, CBAP facilitated Akt-dependent TSC2 phosphorylation in cell-based assays and in vitro analysis, decreased lysosomal localization of TSC2, and elevated Rheb-GTP loading and subsequent activation of mTORC1 signaling. Taken together, our findings reveal a novel oncogenic contribution of CBAP in T-ALL leukemic cells, in addition to its original pro-apoptotic function in cytokine-dependent cell lines and primary hematopoietic cells, by demonstrating its functional role in the regulation of Akt-TSC2-mTORC1 signaling for leukemia cell proliferation. Thus, CBAP represents a novel therapeutic target for many types of cancers and metabolic diseases linked to PI3K-Akt-mTORC1 signaling.

Is surviving enough? Coping and impact on activities of daily living among melanoma patients with lymphoedema

We assessed the impact of lymphoedema (defined as ≥ 10% limb volume change) on quality of life (QOL), ability to perform activities of daily living (ADLs) and coping in 277 melanoma patients. Limb volume was measured prospectively, pre-operatively and every 3-6 months for 18 months post-operatively using a perometer. Three questionnaires were administered to measure QOL, coping and impact on ADLs. Statistical analyses were conducted using longitudinal logistic regression models. At 18 months, the cumulative incidence of lymphoedema was 31% in patients with upper extremity nodal basin treatment and 40% in lower extremity nodal basin treatment patients. Patients with lower extremity lymphoedema reported lower QOL scores than those with upper extremity lymphoedema. Over 18 months, both groups with mild and moderate lymphoedema showed improvement in coping [odds ratio (OR): 6.67, 95% confidence interval (CI): 3.30-13.47] and performance of ADLs (OR: 7.46, CI: 3.38-16.47). Over the course of 18 months, men were found to have poorer coping scores than women (OR: 2.91, CI: 1.35-6.27). Lymphoedema was associated with improvement in coping over time (P = 0.08) and a higher reported interference with ADLs (OR: 2.53, CI: 1.29-4.97). Patient education about lymphoedema at the time of surgical consent may improve self-efficacy and coping ability. Effective management of lymphoedema may improve patient QOL and reduce interference with ADLs.

Association between use of FK506 and prevalence of post-transplantation diabetes mellitus in kidney transplant patients

BACKGROUND

Tacrolimus (FK506) use has been suggested as a risk factor for post-transplantation diabetes mellitus (PTDM) because it can impair insulin secretion. This association warrants further investigation. This study aimed to examine the prevalence of PTDM and its association with FK506 use in kidney transplant recipients. The study also aimed to examine the relationship of FK506 use and diabetes-related biologic markers.

METHODS

A retrospective chart review was used to collect data at a medical center in northern Taiwan from September 2003 to February 2012. PTDM was defined with the use of the criteria of the American Diabetes Association.

RESULTS

Among 166 patients included in the analysis, PTDM was reported in 49 patients (29.5%). A total of 93 patients used the FK506 regimen, of whom 34 (36.6%) were PTDM cases. Logistic regression showed that FK506 use (odds ratio [OR], 2.71; 95% confidence interval [CI], 1.20-6.11; P = .016) and older age (OR,1.08; 95% CI, 1.03-1.13; P = .001) were significant risk factors for PTDM. In addition, FK506 use in PTDM cases was associated with a significantly higher hemoglobin A1c level (7.55 vs 5.81; P = .01) and a borderline significantly higher insulin resistance index (3.24 vs 1.92; P = .053) than was FK506 use without the presence of PTDM.

CONCLUSIONS

Older age and an FK506 regimen were important predictors of the prevalence of PTDM. Greater early detection and prevention efforts for PTDM are needed for older transplant recipients. PTDM patients with an FK506 regimen had higher hemoglobin A1c levels and insulin resistance index than did patients who did not use FK506. The association of serum indicators with FK506 use in the prevalence of PTDM warrants further investigation.

LOUPE-ASSISTED MODIFIED ONE-LAYER VASOVASOSTOMY

Several studies indicate that microsurgical modified one-layer vasovasostomy is comparable to the two-layer anastomosis with respect to patency and pregnancy rates. The objective of this study was to determine the feasibility and result of modified one-layer vasovasostomy under loupe magnification only. Thirty-two patients aged 28 to 64 years (mean 41.3 +/- 6 years) underwent vasovasostomy at CGMH from July 1997 to June 2002, with all operations being a modified on-layer anastomosis created with the aid of a 3 x loupe. The estimated duration of vasectomy ranged from 4 months to 27 years, with a mean of 9.2 +/- 4.8 years. Postoperative semen analysis and pregnancy were examined. Each patient was followed up at 1,4, and 12 weeks postoperatively. The total operation time ranged from 118 to 228 minutes (average 150 +/- 35 minutes). There was no operation-related complication such as hematoma or wound infection. The patency rate was 89% (25/28), and the pregnancy rate at 2 years or more of follow-up was 39% (11/28). The patency and pregnancy rates were similar to those obtained in most studies of microsurgical vasovasostomy. For uncomplicated vasectomy reversal, this simple loupe-assisted modified one-lyer vasovasostomy seems to provide an adequate anastomosis.

GIANT SEMINAL VESICLE CYST RESEMBLING MEGAURETER WITH HYDRONEPHROSIS

Seminal vesicle cysts combined with ipsilateral renal agenesis is a rare congenital anomaly. We report an extreme case whose image resembles megaureter and hydronephrosis. A standard nephrectomy was performed and spermatozoa with flattened, cuboidal, and pseudostratified epithelium was found microscopically. The diagnosis of seminal vesicle cyst was confirmed.

Functional Characterization of CBAP in Controlling Bim-independent Hematopoietic Homeostasis (97.14)

The lifespan of hematopoietic cells is involved in controlling inflammation and autoimmune response. CBAP (Common Beta chain Associating Protein) is a newly annotated membrane bound protein and is identified to associate with Box II domain, highly conserved among cytokine receptor superfamily, of common beta chain (βc) of GM-CSF/IL-3/IL-5 receptor.

In GM-CSF withdrawal-induced cell death assay, CBAP is demonstrated to trigger apoptotic signal, which is involved in Bax/Bak activation, and could be blocked by overexpression of Bcl-2 protein. In order to characterize the biological role of CBAP in vivo, we created the CBAP-deficient mice in either wild-type (wt) or Bim-deficient genetic background. We find that CBAP deficient mice are viable and fertile. The targeted allele could be transmitted according Mendel's Law inside the family, suggesting there is no apparent reproductive defect. In addition, we find the alterations of haematopoietic homeostasis. CBAP-deficiency increased the numbers of T cells, B cells and dendritic cells in the peripheral lymphatic organs in both the wt- and Bim-/- background, suggesting CBAP plays a non-redundant role in regulating hematopoietic homeostasis. CBAP-deficient primary bone marrow-derived dendritic cells (BMDCs) are more resistant to GM-CSF withdrawal-induced cell death, suggesting the contribution of CBAP in the regulation of apoptosis. Taken together, these results suggest the potential role of CBAP in controlling death of hematopoietic cells as well as playing a redundant role of Bim-regulated cell death.

An IL-7 splicing-defect lymphopenia mouse model revealed by genome-wide mutagenesis

Homeostasis of the hematopoietic system is tightly regulated by an array of cytokines that control proliferation, differentiation and apoptosis of various cell lineages. To identify genes that are essential for hematopoietic homeostasis, we screened C57BL/6 mice that had been genome-wide mutagenized by N-ethyl-N-nitrosourea (ENU) to produce altered blood cell composition. We identified a mutant mouse line with a drastic reduction in the number of T and B cell lineages in lymphatic tissues and peripheral blood, as well as severe atrophy of the thymus and lymph nodes. Genotyping with a genome-wide single nucleotide polymorphism (SNP) marker set mapped the mutant phenotype to chromosome 3A and subsequent direct DNA sequencing revealed a G-to-A point mutation in the splicing donor site of the third exon of the candidate gene for IL-7, a lymphocyte survival cytokine. Such mutation resulted in skipping of exon 3 and production of an internally truncated IL-7 (DeltaE3-IL7). Furthermore, using recombinant proteins produced in a baculoviral system, we demonstrated that DeltaE3-IL7 had no detectable anti-apoptotic activity even at a dose that was 30 times more than that required for a wild-type protein to manifest a full activity in a naïve T cell survival assay. Our data suggest that this mutant mouse line provides an alternative animal model for the study of severe combined immunodeficiency (SCID) syndrome in humans.

MAPK-mediated phosphorylation of GATA-1 promotes Bcl-XL expression and cell survival

In the interleukin 3-dependent hematopoietic cell line Ba/F3, inhibition of mitogen-activated protein kinase, a member of the MAPK/c-Jun N-terminal kinase/stress-activated protein kinase kinase family that plays an important role in cell growth and death control, rapidly leads to severe apoptosis. However, most of the antiapoptotic substrates of MAPK remain to be identified. Here we report that, upon interleukin-3 stimulation of Ba/F3 cells, the transcription factor GATA-1 is strongly phosphorylated at residue serine 26 by a MAPK-dependent pathway. Phosphorylation of GATA-1 increases GATA-1-mediated transcription of the E4bp4 survival gene without significantly changing the DNA-binding affinity of GATA-1. Further characterization of GATA-1 phosphorylation site mutants revealed that the antiapoptotic function of GATA-1 is strongly dependent upon its phosphorylation at the Ser-26 position and is probably mediated through its up-regulation of Bcl-X(L) expression. Taken together, our data demonstrate that MAPK-dependent GATA-1 phosphorylation is important for its transactivation of the E4bp4 gene, Bcl-X(L) expression and cell survival. Therefore, GATA-1 may represent a novel MAPK substrate that plays an essential role in a cytokine-mediated antiapoptotic response.

GATA factors are essential for transcription of the survival gene E4bp4 and the viability response of interleukin-3 in Ba/F3 hematopoietic cells

E4bp4, a member of the basic region/leucine zipper transcription factor superfamily, is up-regulated by the interleukin-3 (IL-3) signaling pathway and plays an important role in the anti-apoptotic response of IL-3. In this study, we demonstrated that E4bp4 is regulated by IL-3 mainly at the transcriptional level. Promoter analysis revealed that a GATA motif downstream of a major transcription initiation site is essential for E4bp4 expression in the IL-3-dependent Ba/F3 cell line. Gel shift assays demonstrated that both GATA-1 and GATA-2 proteins bind to the E4bp4 GATA site in vitro, and the chromatin immunoprecipitation assay further confirmed the in vivo binding of GATA-1 to the E4bp4 promoter. Overexpression of GATA-1 alone transactivates the E4bp4 reporter, whereas transactivation of the E4bp4 reporter by GATA-2 is dependent on the stimulation of IL-3. Last, we demonstrated that alteration of GATA-1 binding to the GATA site by stably overexpressing GATA-1 or a GATA-1 mutant containing only the DNA-binding domain not only modulates the expression of the E4bp4 gene but also influences apoptosis induced by IL-3 removal. Taken together, our results suggest that the GATA factors play an important role in transducing the survival signal of IL-3, and one of their cellular targets is E4bp4.

Tuning up or down the UV-induced apoptosis in Chinese hamster ovary cells with cell cycle inhibitors

Exposure to UVC induces apoptosis in Chinese hamster ovary (CHO.K1) cells. While studying the underlying mechanism, we found that a variety of cell cycle inhibitors, including colcemid, hydroxyurea and mimosine, enhance the UV-induced apoptosis in these cells. Such enhancement was not dependent on the cell cycle progression nor was it related to the difference in UV sensitivity at different phases of the cell cycle. The expression of p21(waf1/cip1), a general cyclin-dependent kinase (CDK) inhibitor, was deficient in CHO.K1 cells. Ectopic overexpression of the human p21 markedly increased the survival rates of the UV-irradiated cells in the presence of colcemid. In addition, roscovitine, a small-molecule inhibitor of CDK, also inhibited the UV-induced apoptosis. These observations suggest that deregulation of CDK activity may be critical in the UV-induced apoptosis in CHO.K1 cells.

Liver-derived dendritic cells induce donor-specific hyporesponsiveness: use of sponge implant as a cell transplant model

Spontaneously accepted mouse liver allografts are capable of protecting subsequently transplanted donor organs from rejection; however, the underlying mechanisms are unclear. Dendritic cells (DC) residing in liver grafts are likely important in tolerance induction. DC propagated from mouse liver with GM-CSF are phenotypically and functionally immature. They are poor allostimulators in MLR and prolong survival of pancreatic islet allografts. It has been problematic to perform mechanistic studies in an islet transplant model because of difficulties in obtaining sufficient graft infiltrating cells. In this study, we used a sponge allograft model [i.e.. a subcutaneously implanted sponge matrix loaded with B10 (H2b) spleen cells]. To investigate the influence of administration of donor (B10) liver-derived DC on alloimmune reactivity of C3H (H2k) hosts, sponge graft infiltrating cells (SGIC) and recipient spleen cells were isolated, and their immunophenotype and donor-specific cytotoxic T lymphocyte (CTL) activity were examined. The results illustrate that donor-specific CTL activity of T cells are lower in recipients that had received systemic treatment with liver-derived immature DC, associated with a decrease in CD8+ cell population and an increase in Gr-1+ cells in SGIC, compared with recipients treated with mature bone marrow (BM)-derived DC. Interestingly, administration of liver DC directly into the sponge did not inhibit T cell responses. These data suggest that systemic administration of donor liver DC induces donor-specific hyporesponsiveness, probably not by direct inhibition of graft infiltrating T cells. The increased Gr-1+ cells may play immune regulatory roles in induction of host donor-specific hyporesponsiveness.

Effective treatment of small murine hepatocellular carcinoma by dendritic cells

Hepatocellular carcinoma (HCC) is a common malignancy with a poor prognosis. This investigation examined whether dendritic cell-based immunotherapy can treat murine HCC effectively. Bone marrow-derived dendritic cells were propagated from C57BL/10J mice in GM-CSF (4 ng/mL) and interleukin (IL)-4 (1,000 micro/mL). The dendritic cells were pulsed with a Hepa1-6 lysate overnight and employed to treat murine HCC. For in vivo study, HCC was created by inoculation of hepa1-6, 5 x 10(5) cells, in the flank of C57BL/10J mice. HCC were categorized into small (3 x 3-mm) and large (5 x 5-mm) tumors. These HCC were treated by dendritic cells intravenously, twice at weekly intervals. The results revealed that lymphocytes could be gathered around small HCC after administration of Hepa1-6 lysate-pulsed dendritic cells. Seven of 12 (58.3%) small HCC could be eradicated completely by dendritic cell-based immunotherapy, and 33.3% of the small tumors responded to immunotherapy partially which were held in a stable condition for 34.0 +/- 7.4 days before the tumors regrew. For large HCC, lymphocytes did not gather around the tumors, and the tumors cannot be eradicated effectively by dendritic cells. However, dendritic cell-based immunotherapy could slow down the growth rate of large tumors (116.2 +/- 91.4 mm(3) vs. 234.0 +/- 149.1 mm(3) of the control on day 7, P =.043; and 280.3 +/- 224.7 mm(3) vs. 870.0 +/- 418.9 mm(3) of the control on day 17, P <.001). Conclusively, dendritic cells pulsed with a Hepa1-6 lysate can be employed to treat small HCC in vivo effectively. However, the efficacy of dendritic cell-based immunotherapy decreases while tumors grow.

CREB is one component of the binding complex of the Ces-2/E2A-HLF binding element and is an integral part of the interleukin-3 survival signal

The Ces-2/E2A-HLF binding element (CBE) is recognized by Caenorhabditis elegans death specification gene product Ces-2 and human acute lymphocytic leukemia oncoprotein E2A-HLF. In an attempt to identify a cellular CBE-binding protein(s) that may be involved in apoptosis regulation in mammals, multiple nuclear binding complexes of CBE were identified in various mammalian cell lines and tissues by electrophoretic mobility shift assay. Cyclic AMP (cAMP)-responsive element (CRE)-binding protein (CREB) was present in one major CBE complex of Ba/F3 and TF-1 cells, and both in vitro-translated and Escherichia coli-synthesized CREB bound to CBE. Activation of CREB by cAMP-elevating chemicals or the catalytic subunit of protein kinase A (PKAc) resulted in induction of the CBE-driven reporter gene. Stimulation of Ba/F3 cells with interleukin-3 (IL-3) promptly induced phosphorylation of CREB at serine(133) partially via a PKA-dependent pathway. Consistently, Ba/F3 cell survival in the absence of IL-3 was prolonged by activation of PKA. Conversely, treatment of cells with a PKA inhibitor or expression of the dominant negative forms of the regulatory subunit type I of PKA and CREB overrode the survival activity of IL-3. Last, the bcl-2 gene was demonstrated to be one candidate cellular target of the CREB-containing CBE complex, as mutations in the CRE and CBE sites significantly reduced the IL-3 inducibility of the bcl-2 promoter. Together, our results suggest that CREB is one cellular counterpart of Ces-2/E2A-HLF and is part of IL-3 dependent apoptosis regulation in hematopoietic cells.

The role of free to total prostate-specific antigen ratio for prostate cancer in screening patients with total serum levels between 4 and 20 ng/ml

BACKGROUND

We retrospectively tried to determine if the free to total prostate-specific antigen (f/t PSA) ratio could improve the specificity of PSA in prostate cancer screening of patients with total serum levels between 4 and 20 ng/ml.

METHODS

Two hundred ninety-five patients with serum PSA levels from 4 to 20 ng/ml had undergone sextant prostate needle biopsy. Each patient had no prior history of prostate cancer, acute urine retention, or prostatitis. Prebiopsy free PSA values were measured in 155 patients. Total PSA levels were determined with the AxSYM enzyme-linked immunosorbent assay. Free PSA levels were measured with the AxSYM microparticle enzyme immunoassay.

RESULTS

Mean f/t PSA ratios were 0.114+/-0.004 in men of the cancer group and 0.161+/-0.008 in men of the benign group (p<0.002). Based on the analysis of sensitivity and specificity in relation to f/t PSA ratios, use of the 18% cutoff point could detect 89% of cancer cases, and at the same time could avoid 35% of unnecessary prostate biopsies. The areas under the receiver-of-characteristic curve for f/t PSA ratio and total PSA were 0.649 and 0.545, respectively.

CONCLUSION

Serum f/t PSA ratios were significantly lower in patients with prostate cancer than in patients with benign disease. The determination of an appropriate f/t PSA ratio should be based on the generated data such as that demonstrated in this study in order to improve diagnostic accuracy and specificity for patients with equivocal PSA values and to avoid conducting unnecessary prostate biopsies.

Cbl-b regulates the CD28 dependence of T-cell activation

Whereas co-stimulation of the T-cell antigen receptor (TCR) and CD28 triggers T-cell activation, stimulation of the TCR alone may result in an anergic state or T-cell deletion, both possible mechanisms of tolerance induction. Here we show that T cells that are deficient in the adaptor molecule Cbl-b (ref. 3) do not require CD28 engagement for interleukin-2 production, and that the Cbl-b-null mutation (Cbl-b(-/-)) fully restores T-cell-dependent antibody responses in CD28-/- mice. The main TCR signalling pathways, such as tyrosine kinases Zap-70 and Lck, Ras/mitogen-activated kinases, phospholipase Cgamma-1 and Ca2+ mobilization, were not affected in Cbl-b(-/-) T cells. In contrast, the activation of Vav, a guanine nucleotide exchange factor for Rac1/Rho/CDC42, was significantly enhanced. Our findings indicate that Cbl-b may influence the CD28 dependence of T-cell activation by selectively suppressing TCR-mediated Vav activation. Mice deficient in Cbl-b are highly susceptible to experimental autoimmune encephalomyelitis, suggesting that the dysregulation of signalling pathways modulated by Cbl-b may also contribute to human autoimmune diseases such as multiple sclerosis.

Enterovesical fistula: experiences with 41 cases in 12 years

BACKGROUND

A retrospective analysis of enterovesical fistula treated at Chang Gung Memorial Hospital was conducted to determine the optimal diagnosis and management of this disease.

METHODS

The records of 41 patients who presented from 1984 to 1996 and had a final diagnosis of enterovesical fistula were retrospectively reviewed. The etiology, symptoms on presentation, diagnostic tools, and modality of treatment were analyzed.

RESULTS

The majority of these cases were associated with malignancy (38, 92.7%), and the others with diverticulitis (2, 4.9%) and iatrogenic causes (1, 2.4%). In those with malignancy, 15 patients (39.5%) were found to have tumor recurrence. The most frequent symptom in enterovesical fistula was fecaluria (58.5%), followed by abdominal pain (22%) and dysuria (14.6%). Diagnostic tools included the barium enema, cystography, and cystoscopy; these methods could identify the fistula in 63.2%, 60%, and 53.8% of the patients, respectively. Methods of management included diversion only (39%), one-stage fistula repair (36.6%), and watchful surveillance (24.4%).

CONCLUSION

Enterovesical fistula should be considered if fecaluria, pneumaturia, or persistent non-specific urinary tract infection present as the initial complaint. A thorough surgery for a possible underlying malignancy is mandatory when confronted with enterovesical fistula, since the incidence of inflammatory bowel disease is low in this area. An abdominal computer tomography (CT) scan, barium enema, and cystogram can be useful diagnostic tools. Treatment of this entity should be individualized according to each patients clinical status.

Application of cryoablation in the management of prostate cancer

BACKGROUND

Radical prostatectomy is the most common and effective therapy for localized prostate cancer. But in addition to its surgical complications, even highly selected series carry a positive margin rate of 35 to 50%. Radiotherapy is another alternative for prostate cancer, but following radiotherapy there have been high positive biopsies reported. Cryosurgery, defined as in situ freezing and hence, devitalization of neoplastic tissues, has currently raised the interest of urologists in the management of localized prostate cancer or failed radiotherapy.

MATERIAL

Five patients underwent transperineal cryosurgery of prostate in Chang Gung Memorial Hospital. Among them, three cases were stage D, one stage B and another failed radiotherapy of stage C prostate cancer. All patients received hormone therapy too.

RESULTS

PSA declined in 3 patients and biopsies showed intraductal neoplasia. All 5 patients suffered from urine incontinence and one persisted. No mortality has been reported.

CONCLUSION

Cryoablation of the prostate is an alternative for treatment of prostate cancer.

[Analysis of 117 cases of hypospadias--its location, operation and complication]

Hypospadias is a common congenital anomaly in male newborns. The incidence is about one in 300 live male births. In the U.S., about 6000 boys with hypospadias are born each year. For this study, we collected 117 recent (with the last 5 years) cases (88 fresh and 29 referred) who received an operation in our department. We calculated the hypospadias location and the complication rate with the desire of finding out the relationships between them. Our overall complication rate is 51.3% which is much higher than other recent studies and may be related to a different distribution of the hypospadias locations.

The clinical manifestations of the tuberculous pleural effusion in adult patients

The clinical data of 52 patients with tuberculous pleural effusion were analyzed. Their average age was 48 years old. Thirty two (62%) of them were sick for less than one week. Fever, chest pain and cough were the predominant pictures. Six of the 52 patients had coexisting disease. Intermediate strength protein purified derivative (PPD) test was found to be positive in 14 out of 31 (45%) patients. Their pleural effusions were usually unilateral, right-sided, and nearly half of them occupied more than half of the hemithorax. One third of these patients and concomitant pulmonary tuberculosis and pleural effusion. None of the patients had grossly bloody effusion. All of the effusions were exudative, and the glucose levels in the pleural fluid were invariably above 60 mg/dl. Presence of mesothelial cells in the pleural fluid was found in 28% of them, but none of the patients presented with significant eosinophils in the pleural fluid. Pleural fluid and sputum cultures for Mycobacterium tuberculosis usually reveal a negative study unless a concomitant pulmonary lesion was present. Combined antituberculosis and prednisolone treatment decreased the duration of constitutional symptoms and hastened the resolution of pleural effusion. In conclusion, tuberculous pleural effusion should be considered in elderly patients presenting with massive exudative pleural effusion even with a negative PPD study. Cultures of sputum and pleural fluid are less helpful in patients without parenchymal disease. Prednisolone is recommended in extremely ill patients.