Surgical treatment of acromioclavicular joint dislocation of Rockwood III/IV: a retrospective study on clavicular hook plate versus arthroscopic TightRope loop titanium button.

PURPOSE: To compare the clinical efficacy of arthroscopic TightRope loop titanium button and clavicular hook plate in the treatment of acromioclavicular joint (ACJ) dislocation of Rockwood III/IV. METHODS: A retrospective analysis of patients with ACJ dislocation in our hospital from January 2018 to December 2020 was conducted. The patients were assigned to be treated with arthroscopic TightRope loop titanium button (TR group) or clavicular hook plate (HP group). The preoperative, intraoperative and postoperative data and imaging findings of the two groups were compared. RESULTS: A total of 58 eligible patients were enrolled in this study. Compared with HP group, TR group had shorter incision length and less blood loss during operation. Postoperative follow-up ranged from 12 to 24 months (mean 15.4 months). At 6 months and 12months postoperatively, compared with HP group, TR group had lower VAS and higher CMS, and the difference was statistically significant. At 12 months postoperatively, compared with HP group, TR group had lower ACJ gap and coracoclavicular joint(CCJ) distance, and the difference was statistically significant.In HP group, there were 3 cases of subacromial impact, 1 case of redislocation, 2 cases of traumatic arthritis and 2 cases of wound infection. There was 1 case of redislocation in TR group. CONCLUSIONS: Compared with clavicular hook plate, arthroscopic TightRope loop titanium button is minimally invasive, safe and effective in the treatment of ACJ dislocation, and has a good trend in clinical application.

The hydroxyapatite modified 3D printed poly L-lactic acid porous screw in reconstruction of anterior cruciate ligament of rabbit knee joint: a histological and biomechanical study.

BACKGROUND: 3D printing technology has become a research hotspot in the field of scientific research because of its personalized customization, maneuverability and the ability to achieve multiple material fabrications. The focus of this study is to use 3D printing technology to customize personalized poly L-lactic acid (PLLA) porous screws in orthopedic plants and to explore its effect on tendon-bone healing after anterior cruciate ligament (ACL) reconstruction. METHODS: Preparation of PLLA porous screws with good orthogonal pore structure by 3D printer. The hydroxyapatite (HA) was adsorbed on porous screws by electrostatic layer-by-layer self-assembly (ELSA) technology, and PLLA-HA porous screws were prepared. The surface and spatial morphology of the modified screws were observed by scanning electron microscopy (SEM). The porosity of porous screw was measured by liquid displacement method. Thirty New Zealand male white rabbits were divided into two groups according to simple randomization. Autologous tendon was used for right ACL reconstruction, and porous screws were inserted into the femoral tunnel to fix the transplanted tendon. PLLA group was fixed with porous screws, PLLA-HA group was fixed with HA modified porous screws. At 6 weeks and 12 weeks after surgery, 5 animals in each group were sacrificed randomly for histological examination. The remaining 5 animals in each group underwent Micro-CT and biomechanical tests. RESULTS: The pores of PLLA porous screws prepared by 3D printer were uniformly distributed and connected with each other, which meet the experimental requirements. HA was evenly distributed in the porous screw by ELSA technique. Histology showed that compared with PLLA group, mature bone trabeculae were integrated with grafted tendons in PLLA-HA group. Micro-CT showed that the bone formation index of PLLA-HA group was better than that of PLLA group. The new bone was uniformly distributed in the bone tunnel along the screw channel. Biomechanical experiments showed that the failure load and stiffness of PLLA-HA group were significantly higher than those of PLLA group. CONCLUSIONS: The 3D printed PLLA porous screw modified by HA can not only fix the grafted tendons, but also increase the inductivity of bone, promote bone growth in the bone tunnel and promote bone integration at the tendon-bone interface. The PLLA-HA porous screw is likely to be used in clinic in the future.

MMTV promoter-regulated caveolin-1 overexpression yields defective parenchymal epithelia in multiple exocrine organs of transgenic mice.

Caveolin-1 (Cav-1) is a major structural protein of caveolae, specialized plasma membrane invaginations that are involved in a cell-specific fashion in diverse cell activities such as molecular transport, cell adhesion, and signal transduction. In normal adult mammals, Cav-1 expression is abundant in mesenchyme-derived cells but relatively low in epithelial parenchyma. However, epithelial Cav-1 overexpression is associated with development and/or progression of many carcinomas. In this study, we generated and characterized a transgenic mouse model of Cav-1 overexpression under the control of a mouse mammary tumor virus (MMTV) long terminal-repeat promoter, which is predominantly expressed in specific epithelial cells. The MMTVcav-1(+) transgenic mice were fertile, and females bore litters of normal size with no obvious developmental abnormalities. However, by age 11months, the MMTVcav-1(+) mice demonstrated overtly different phenotypes in multiple exocrine organs when compared with their nontransgenic MMTVcav-1(-) littermates. Cav-1 overexpression in MMTVcav-1(+) mice produced organ-specific abnormalities, including hypotrophy of mammary glandular epithelia, bronchiolar epithelial hyperplasia and atypia, mucous-cell hyperplasia in salivary glands, elongated hair follicles and dermal thickening in the skin, and reduced accumulation of enzymogen granules in pancreatic acinar cells. In addition, the MMTVcav-1(+) transgenic mice tended to have a greater incidence of malignant tumors, including lung and liver carcinomas and lymphoma, than their MMTVcav-1(-) littermates. Our results indicate that Cav-1 overexpression causes organ-specific, age-related epithelial disorders and suggest the potential for increased susceptibility to carcinogenesis.

Caveolin-1 maintains activated Akt in prostate cancer cells through scaffolding domain binding site interactions with and inhibition of serine/threonine protein phosphatases PP1 and PP2A.

Previously it has been reported that caveolin-1 (cav-1) has antiapoptotic activities in prostate cancer cells and functions downstream of androgenic stimulation. In this study, we demonstrate that cav-1 overexpression significantly reduced thapsigargin (Tg)-stimulated apoptosis. Examination of the phosphatidylinositol 3-kinase (PI3-K)/Akt signaling cascade revealed higher activities of PDK1 and Akt but not PI3-K in cav-1-stimulated cells compared to control cells. We subsequently found that cav-1 interacts with and inhibits serine/threonine protein phosphatases PP1 and PP2A through scaffolding domain binding site interactions. Deletion of the cav-1 scaffolding domain significantly reduces phosphorylated Akt and cell viability compared with wild-type cav-1. Analysis of potential substrates for PP1 and PP2A revealed that cav-1-mediated inhibition of PP1 and PP2A leads to increased PDK1, Akt, and ERK1/2 activities. We demonstrate that increased Akt activities are largely responsible for cav-1-mediated cell survival using dominant-negative Akt mutants and specific inhibitors to MEK1/MEK and show that cav-1 increases the half-life of phosphorylated PDK1 and Akt after inhibition of PI3-K by LY294002. We further demonstrate that cav-1-stimulated Akt activities lead to increased phosphorylation of multiple Akt substrates, including GSK3, FKHR, and MDM2. In addition, overexpression of cav-1 significantly increases translocation of phosphorylated androgen receptor to nucleus. Our studies therefore reveal a novel mechanism of Akt activation in prostate cancer and potentially other malignancies.

mRTVP-1, a novel p53 target gene with proapoptotic activities.

We identified a novel mouse gene, mRTVP-1, as a p53 target gene using differential display PCR and extensive promoter analysis. The mRTVP-1 protein has 255 amino acids and differs from the human RTVP-1 (hRTVP-1) protein by two short in-frame deletions of two and nine amino acids. RTVP-1 mRNA was induced in multiple cancer cell lines by adenovirus-mediated delivery of p53 and by gamma irradiation or doxorubicin both in the presence and in the absence of endogenous p53. Analysis of RTVP-1 expression in nontransformed and transformed cells further supported p53-independent gene regulation. Using luciferase reporter and electrophoretic mobility shift assays we identified a p53 binding site within intron 1 of the mRTVP-1 gene. Overexpression of mRTVP-1 or hRTVP-1 induced apoptosis in multiple cancer cell lines including prostate cancer cell lines 148-1PA, 178-2BMA, PC-3, TSU-Pr1, and LNCaP, a human lung cancer cell line, H1299, and two isogenic human colon cancer cell lines, HCT116 p53(+/+) and HCT116 p53(-/-), as demonstrated by annexin V positivity, phase-contrast microscopy, and in selected cases 4',6'-diamidino-2-phenylindole staining and DNA fragmentation. Deletion of the signal peptide from the N terminus of RTVP-1 reduced its apoptotic activities, suggesting that a secreted and soluble form of RTVP-1 may mediate, in part, its proapoptotic activities.

RTVP-1, a tumor suppressor inactivated by methylation in prostate cancer.

We previously identified and characterized a novel p53-regulated gene in mouse prostate cancer cells that was homologous to a human gene that had been identified in brain cancers and termed RTVP-1 or GLIPR. In this report, we document that the human RTVP-1 gene is also regulated by p53 and induces apoptosis in human prostate cancer cell lines. We show that the expression of the human RTVP-1 gene is down-regulated in human prostate cancer specimens compared with normal human prostate tissue at the mRNA and protein levels. We further document epigenetic changes consistent with RTVP-1 being a tumor suppressor in human prostate cancer.

Caveolin-1 regulates hormone resistance through lipid synthesis, creating novel therapeutic opportunities for castration-resistant prostate cancer.

Caveolin-1 (Cav-1) is overexpressed in aggressive and metastatic prostate cancer (PCa) and induces PCa cell proliferation. Androgens mediate lipid synthesis through acetyl-CoA carboxylase-1 (ACC1) and fatty acid synthase (FASN). We investigated the Cav-1-mediated lipid synthesis in the development of castration resistance, and identified novel therapeutic opportunities. Using the PBCre+;Ptenloxp/loxp;PBCav-1+ mouse model we found that Cav-1 induction increased cancer incidence and growth, and ACC1-FASN expression in intact and castrated mice. We demonstrated that Cav-1 regulated ACC1 and FASN expression in an AR-independent way and increased palmitate synthesis using western blot analysis, qRT-PCR and mass spectrometry in vitro. By using FASN siRNA and C-75, we found that FASN inhibition was more effective in Cav-1-overexpressing cells. This inhibition was abrogated by ACC1si RNA, revealing the role of malonyl-CoA, an ACC1 product, as a mediator of cytotoxicity. Cav-1 was associated with ACC1 in human tumors and ACC1, FASN, and Cav-1 expression were increased in metastatic PCa compared to primary tumors and normal prostate epithelium. Palmitoleate and oleate levels were higher in BMA from patients with metastatic PCa who responded poorly to abiraterone acetate. Our findings suggest that Cav-1 promotes hormone resistance through the upregulation of ACC1-FASN and lipid synthesis under androgen deprivation, suggesting that FASN inhibition could be used to treat PCa that demonstrates Cav-1 overexpression.

Development of an immunoassay for serum caveolin-1: a novel biomarker for prostate cancer.

PURPOSE: Caveolin-1 (cav-1), the major protein component of caveolae, plays an important role in multiple signaling pathways, molecular transport, and cellular proliferation and differentiation. The specific functions of cav-1/caveolae are highly cell and context dependent. We have previously shown that cav-1 expression is increased in metastatic human prostate cancer and that cav-1 cellular protein expression is predictive of recurrence of the disease after radical prostatectomy. Recently, we reported that cav-1 is secreted by androgen-insensitive prostate cancer cells, and we detected, by Western blotting, cav-1 in the high-density lipoprotein(3) fraction of serum specimens from patients with prostate cancer. EXPERIMENTAL DESIGN: Using rabbit polyclonal antibodies with specificity for cav-1, we developed a direct sandwich immunoassay for the determination of cav-1 in serum. A recombinant human cav-1 fusion protein was overexpressed and purified from 293 PE cells and used as a calibrator. RESULTS: The assay was highly specific and had a minimum detection limit of 0.017 ng/ml (mean + 3 SD of zero calibrator) and measuring range of up to 200 ng/ml. Intra-assay coefficient of variation was 2.29-6.74% and inter-assay coefficient of variation was 2.81-6.43% over the serum concentration tested 0.04-31.89 ng/ml. The recovery limit of cav-1 by the assay was 89.55-100.28%. The median serum cav-1 level in 102 prostate cancer patients with clinically localized disease (0.463 ng/ml) was significantly higher than 81 healthy control men (0.324 ng/ml; P = 0.0446, Mann-Whitney test) or 107 men with benign prostatic hyperplasia (0.172 ng/ml; P = 0.0317, Mann-Whitney test). CONCLUSIONS: Our results indicate that serum cav-1 has the power to differentiate between prostate cancer and benign prostatic hyperplasia patients and the potential to be an important biomarker for prostate cancer. Additional studies to test the potential of serum cav-1 as a diagnostic and/or prognostic marker in prostate cancer are warranted.

Adenoviral vector-mediated mRTVP-1 gene therapy for prostate cancer.

We previously identified the mouse RTVP-1 (mRTVP-1; related to testes-specific, vespid, and pathogenesis proteins) gene as a direct target of p53 with proapoptotic activities in various cancer cell lines, including prostate cancer. To test the therapeutic potential of mRTVP-1 we constructed an adenoviral vector capable of efficient transduction and expression of mRTVP-1 (AdmRTVP-1) and used this vector in an orthotopic, metastatic mouse model of prostate cancer. A single intratumoral administration of AdmRTVP-1 gene therapy significantly reduced primary tumor wet weight compared with control Adbetagal-injected tumors at two time points after injection with two different vector doses (p < or = 0.01 at 7 and 14 days). Spontaneous metastasis to lung was also significantly reduced (p < or = 0.02). Evaluation of treated tumors revealed increased apoptosis and lower microvessel density counts. In a rat aortic ring sprouting assay, AdmRTVP-1 inhibited endothelial cell sprouting compared with Adbetagal, confirming its antiangiogenic activity. These therapeutic activities were associated with a significant increase in survival from 22.9 to 26.8 days (p = 0.003) in this aggressive model of prostate cancer. Interestingly, there were significant increases in the infiltration of tumor-associated macrophages, dendritic cells, and CD8+ T cells, which persisted at 14 days posttreatment in the AdmRTVP-1-treated tumors compared with Adbetagal control-treated tumors. In addition, significantly increased natural killer and cytotoxic T lymphocyte activities were demonstrated in the mice with AdmRTVP-1-treated tumors. The unique therapeutic properties of AdmRTVP-1 gene therapy demonstrated in this study provide new opportunities for gene and immunotherapy of prostate cancer and potentially other malignancies.

Targeting poly(ADP-ribose) polymerase and the c-Myb-regulated DNA damage response pathway in castration-resistant prostate cancer.

Androgen deprivation is the standard treatment for advanced prostate cancer (PCa), but most patients ultimately develop resistance and tumor recurrence. We found that MYB is transcriptionally activated by androgen deprivation therapy or genetic silencing of the androgen receptor (AR). MYB silencing inhibited PCa growth in culture and xenografts in mice. Microarray data revealed that c-Myb and AR shared a subset of target genes that encode DNA damage response (DDR) proteins, suggesting that c-Myb may supplant AR as the dominant regulator of their common DDR target genes in AR inhibition-resistant or AR-negative PCa. Gene signatures including AR, MYB, and their common DDR-associated target genes positively correlated with metastasis, castration resistance, tumor recurrence, and decreased survival in PCa patients. In culture and in xenograft-bearing mice, a combination strategy involving the knockdown of MYB, BRCA1, or TOPBP1 or the abrogation of cell cycle checkpoint arrest with AZD7762, an inhibitor of the checkpoint kinase Chk1, increased the cytotoxicity of the poly[adenosine 5'-diphosphate (ADP)-ribose] polymerase (PARP) inhibitor olaparib in PCa cells. Our results reveal new mechanism-based therapeutic approaches for PCa by targeting PARP and the DDR pathway involving c-Myb, TopBP1, ataxia telangiectasia mutated- and Rad3-related (ATR), and Chk1.

Caveolin-1-LRP6 signaling module stimulates aerobic glycolysis in prostate cancer.

Caveolin 1 (Cav-1) is a plasma membrane-associated protein with the capacity to modulate signaling activities in a context-dependent fashion. Interactions between Cav-1 and low-density lipoprotein receptor-related protein 6 (LRP6) were reported to be important for the regulation of Wnt-ß-catenin (ß-cat) signaling. Cav-1 also interacts with insulin and IGF-I receptors (IGF-IR/IR) and can stimulate IR kinase activities. We found positive correlation between Cav-1 and LRP6 expression in both human primary prostate cancer and metastasis tissues and in PC-3 cells. Cav-1 stimulation of Wnt-ß-cat signaling and c-Myc levels was positively associated with LRP6 expression in LNCaP, PC-3, and DU145 prostate cancer cells. Importantly, LRP6 and, to a lesser extent, Cav-1 were found to stimulate aerobic glycolysis. These activities were positively associated with the expression of HK2 and Glut3 and shown to be dependent on Akt signaling by both gene knockdown and chemical inhibition methods. We further showed that Cav-1 and LRP6 exert their effects on Akt and glycolytic activities by stimulating IGF-IR/IR signaling. Overall, our results show that Cav-1 interacts with LRP6 to generate an integrated signaling module that leads to the activation of IGF-IR/IR and results in stimulation of Akt-mTORC1 signaling and aerobic glycolysis in prostate cancer.

Glioma pathogenesis-related protein 1 induces prostate cancer cell death through Hsc70-mediated suppression of AURKA and TPX2.

In this study we report that expression of glioma pathogenesis-related protein 1 (GLIPR1) regulated numerous apoptotic, cell cycle, and spindle/centrosome assembly-related genes, including AURKA and TPX2, and induced apoptosis and/or mitotic catastrophe (MC) in prostate cancer (PCa) cells, including p53-mutated/deleted, androgen-insensitive metastatic PCa cells. Mechanistically, GLIPR1 interacts with heat shock cognate protein 70 (Hsc70); this interaction is associated with SP1 and c-Myb destabilization and suppression of SP1- and c-Myb-mediated AURKA and TPX2 transcription. Inhibition of AURKA and TPX2 using siRNA mimicked enforced GLIPR1 expression in the induction of apoptosis and MC. Recombinant GLIPR1-ΔTM protein inhibited AURKA and TPX2 expression, induced apoptosis and MC, and suppressed orthotopic xenograft tumor growth. Our results define a novel GLIPR1-regulated signaling pathway that controls apoptosis and/or mitotic catastrophe in PCa cells and establishes the potential of this pathway for targeted therapies.

Caveolin-1 upregulation contributes to c-Myc-induced high-grade prostatic intraepithelial neoplasia and prostate cancer.

Previously we reported caveolin-1 (Cav-1) overexpression in prostate cancer cells and showed that it promotes prostate cancer progression. Here, we report that Cav-1 was overexpressed in 41.7% (15 of 36) of human high-grade prostatic intraepithelial neoplasia (HGPIN) specimens obtained during radical prostatectomies. Positive correlations exist between Cav-1-positive (Cav-1(+)) HGPIN and Cav-1(+) primary prostate cancer (rho = 0.655, P < 0.0001) and between Cav-1 and c-Myc expression in HGPIN (rho = 0.41, P = 0.032). To determine whether Cav-1 cooperates with c-Myc in development of premalignant lesions and prostate cancer in vivo, we generated transgenic mice with c-Myc overexpression driven by the ARR(2)PB promoter. In this ARR(2)PB-c-myc model, Cav-1 overexpression was found in mouse PIN (mPIN) lesions and prostate cancer cells and was associated with a significantly higher ratio of proliferative to apoptotic labeling in mPIN lesions than in the Cav-1-negative epithelia adjacent to those lesions (10.02 vs. 4.34; P = 0.007). Cav-1 overexpression was also associated with increased levels of P-Akt and VEGF-A, which were previously associated with Cav-1-induced prostate cancer cell survival and positive feedback regulation of cellular Cav-1 levels, respectively. In multiple prostate cancer cell lines, Cav-1 protein (but not mRNA) was induced by c-Myc transfection, whereas VEGF siRNA transfection abrogated c-Myc-induced Cav-1 overexpression, suggesting a c-Myc-VEGF-Cav-1 signaling axis. Overall, our results suggest that Cav-1 is associated with c-Myc in the development of HGPIN and prostate cancer. Furthermore, Cav-1 overexpression in HGPIN is potentially a biomarker for early identification of patients who tend to develop Cav-1(+) primary prostate cancer.

GLIPR1 suppresses prostate cancer development through targeted oncoprotein destruction.

Downregulation of the proapoptotic p53 target gene glioma pathogenesis-related protein 1 (GLIPR1) occurs frequently in prostate cancer, but the functional meaning of this event is obscure. Here, we report the discovery of functional relationship between GLIPR1 and c-Myc in prostate cancer where c-Myc is often upregulated. We found that the expression of GLIPR1 and c-Myc were inversely correlated in human prostate cancer. Restoration of GLIPR1 expression in prostate cancer cells downregulated c-myc levels, inhibiting cell-cycle progression. Downregulation was linked to a reduction in ß-catenin/TCF4-mediated transcription of the c-myc gene, which was caused by GLIPR1-mediated redistribution of casein kinase 1α (CK1α) from the Golgi apparatus to the cytoplasm where CK1α could phosphorylate ß-catenin and mediate its destruction. In parallel, GLIPR1 also promoted c-Myc protein ubiquitination and degradation by glycogen synthase kinase-3α- and/or CK1α-mediated c-Myc phosphorylation. Notably, genetic ablation of the mouse homolog of Glipr1 cooperated with c-myc overexpression to induce prostatic intraepithelial neoplasia and prostate cancer. Together, our findings provide evidence for CK1α-mediated destruction of c-Myc and identify c-Myc S252 as a crucial CK1α phosphorylation site for c-Myc degradation. Furthermore, they reveal parallel mechanisms of c-myc downregulation by GLIPR1 that when ablated in the prostate are sufficient to drive c-Myc expression and malignant development.

GLIPR1 tumor suppressor gene expressed by adenoviral vector as neoadjuvant intraprostatic injection for localized intermediate or high-risk prostate cancer preceding radical prostatectomy.

BACKGROUND: GLIPR1 is upregulated by p53 in prostate cancer cells and has preclinical antitumor activity. A phase I clinical trial was conducted to evaluate the safety and activity of the neoadjuvant intraprostatic injection of GLIPR1 expressing adenovirus for intermediate or high-risk localized prostate cancer before radical prostatectomy (RP). METHODS: Eligible men had localized prostate cancer (T1-T2c) with Gleason score greater than or equal to 7 or prostate-specific antigen 10 ng/mL or more and were candidates for RP. Patients received the adenoviral vector expressing the GLIPR1 gene by a single injection into the prostate followed four weeks later by RP. Six viral particle (vp) dose levels were evaluated: 10(10), 5 × 10(10), 10(11), 5 × 10(11), 10(12), and 5 × 10(12) vp. RESULTS: Nineteen patients with a median age of 64 years were recruited. Nine men had T1c, 4 had T2a, and 3 had T2b and T2c clinical stage. Toxicities included urinary tract infection (n = 3), flu-like syndrome (n = 3), fever (n = 1), dysuria (n = 1), and photophobia (n = 1). Laboratory toxicities were grade 1 elevated AST/ALT (n = 1) and elevations of PTT (n = 3, with 1 proven to be lupus anticoagulant). No pathologic complete remission was seen. Morphologic cytotoxic activity, induction of apoptosis, and nuclear p27(Kip1) upregulation were observed. Peripheral blood CD8(+), CD4(+), and CD3(+) T-lymphocytes were increased, with upregulation of their HLA-DR expression and elevations of serum IL-12. CONCLUSIONS: The intraprostatic administration of GLIPR1 tumor suppressor gene expressed by an adenoviral vector was safe in men, with localized intermediate or high-risk prostate cancer preceding RP. Preliminary evidence of biologic antitumor activity and systemic immune response was documented.

Caveolin-1 promotes autoregulatory, Akt-mediated induction of cancer-promoting growth factors in prostate cancer cells.

Caveolin-1 (cav-1) and the cancer-promoting growth factors vascular endothelial growth factor (VEGF), transforming growth factor beta1 (TGF-beta1), and fibroblast growth factor 2 (FGF2) are often found to be upregulated in advanced prostate cancer and other malignancies. However, the relationship between cav-1 overexpression and growth factor upregulation remains unclear. This report presents, to our knowledge, the first evidence that in prostate cancer cells, a positive autoregulatory feedback loop is established in which VEGF, TGF-beta1, and FGF2 upregulate cav-1, and cav-1 expression, in turn, leads to increased levels of VEGF, TGF-beta1, and FGF2 mRNA and protein, resulting in enhanced invasive activities of prostate cancer cells, i.e., migration and motility. Our results further show that cav-1-enhanced mRNA stability is a major mechanism underlying the upregulation of these cancer-promoting growth factors, and that PI3-K-Akt signaling is required for forming this positive autoregulatory feedback loop.

Glioma pathogenesis-related protein 1 exerts tumor suppressor activities through proapoptotic reactive oxygen species-c-Jun-NH2 kinase signaling.

Glioma pathogenesis-related protein 1 (GLIPR1), a novel p53 target gene, is down-regulated by methylation in prostate cancer and has p53-dependent and -independent proapoptotic activities in tumor cells. These properties suggest an important tumor suppressor role for GLIPR1, yet direct genetic evidence of a tumor suppressor function for GLIPR1 is lacking and the molecular mechanism(s), through which GLIPR1 exerts its tumor suppressor functions, has not been shown. Here, we report that the expression of GLIPR1 is significantly reduced in human prostate tumor tissues compared with adjacent normal prostate tissues and in multiple human cancer cell lines. Overexpression of GLIPR1 in cancer cells leads to suppression of colony growth and induction of apoptosis. Mice with an inactivated Glipr1 gene had significantly shorter tumor-free survival times than either Glipr1(+/+) or Glipr1(+/-) mice in both p53(+/+) and p53(+/-) genetic backgrounds, owing to their development of a unique array of malignant tumors. Mechanistic analysis indicated that GLIPR1 up-regulation increases the production of reactive oxygen species (ROS) leading to apoptosis through activation of the c-Jun-NH(2) kinase (JNK) signaling cascade. Thus, our results identify GLIPR1 as a proapoptotic tumor suppressor acting through the ROS-JNK pathway and support the therapeutic potential for this protein.

Identification and characterization of RTVP1/GLIPR1-like genes, a novel p53 target gene cluster.

Our previous finding of RTVP1 (GLIPR1) as a p53 target gene with tumor suppressor functions prompted us to initiate a genome-wide sequence homology search for RTVP1/GLIPR1-like (GLIPR1L) genes. In this study we report the identification and characterization of a novel p53 target gene cluster that includes human RTVP1 (hRTVP-1) together with two GLIPR1L genes (GLIPR1L1 and GLIPR1L2) on human chromosome 12q21 and mouse Rtvp1 (mRTVP-1 or Glipr1) together with three Glipr1-like (Glipr1l) genes on mouse chromosome 10D1. GLIPR1L1 has two and GLIPR1L2 has five differentially spliced isoforms. Protein homology search revealed that hRTVP-1 gene cluster members share a high degree of identity and homology. GLIPR1L1 is testis-specific, whereas GLIPR1L2 is expressed in different types of tissues, including prostate and bladder. Like hRTVP-1, GLIPR1L1 and GLIPR1L2 are p53 target genes. The similarities of these novel p53 target gene cluster members in protein structure and their association with p53 suggest that these genes may have similar biological functions.

The role of caveolin-1 in androgen insensitive prostate cancer.

PURPOSE: We summarize the literature regarding androgen insensitive prostate cancer and caveolin-1. Caveolin-1 is a major structural component of caveolae, membrane micro-domains known to have important roles in signal transduction and lipid transport. MATERIALS AND METHODS: A review of the literature relevant to androgen insensitive caveolin-1 and prostate cancer included the first published report in 1998 through those published in March 2002. RESULTS: Caveolin-1 expression is increased in primary and metastatic human prostate cancer with highest levels observed after androgen ablation therapy. Recent studies have documented that caveolin-1 is secreted by prostate cancer cells and can be detected in the serum of men with prostate cancer. CONCLUSIONS: The results presented in this review establish that caveolin-1 is an autocrine/paracrine factor associated with androgen insensitive prostate cancer. They show the potential for caveolin-1 as a biomarker therapeutic target for this important malignancy.

Disruption of the caveolin-1 gene impairs renal calcium reabsorption and leads to hypercalciuria and urolithiasis.

Using LoxP/Cre technology, we generated a knockout mouse homozygous for a null mutation in exon 2 of Cav1. In male Cav1-/- animals, we observed a dramatic increase in the incidence of urinary calcium stone formation. In 5-month-old male mice, the incidence of early urinary calculi was 67% in Cav1-/- mice compared to 19% in Cav1+/+ animals. Frank stone formation was observed in 13% of Cav1-/- males but was not seen in Cav1+/+ mice. Urine calcium concentration was significantly higher in Cav1-/- male mice compared to Cav1+/+ mice. In Cav1-/- mice, distal convoluted tubule cells were completely devoid of Cav1 and the localization of plasma membrane calcium ATPase was disrupted. Functional studies confirmed that active calcium absorption was significantly reduced in Cav1-/- compared to Cav1+/+ male mice. These results demonstrate that disruption of the Cav1 gene promotes the progressive steps required for urinary calcium stone formation and establish a new mouse model for urinary stone disease.