Knowledge translation and implementation in spinal cord injury: a systematic review.

OBJECTIVE: To conduct a systematic review examining the effectiveness of knowledge translation (KT) interventions in changing clinical practice and patient outcomes. METHODS: MEDLINE/PubMed, CINAHL, EMBASE and PsycINFO were searched for studies published from January 1980 to July 2012 that reported and evaluated an implemented KT intervention in spinal cord injury (SCI) care. We reviewed and summarized results from studies that documented the implemented KT intervention, its impact on changing clinician behavior and patient outcomes as well as the facilitators and barriers encountered during the implementation. RESULTS: A total of 13 articles featuring 10 studies were selected and abstracted from 4650 identified articles. KT interventions included developing and implementing patient care protocols, providing clinician education and incorporating outcome measures into clinical practice. The methods (or drivers) to facilitate the implementation included organizing training sessions for clinical staff, introducing computerized reminders and involving organizational leaders. The methodological quality of studies was mostly poor. Only 3 out of 10 studies evaluated the success of the implementation using statistical analyses, and all 3 reported significant behavior change. Out of the 10 studies, 6 evaluated the effect of the implementation on patient outcomes using statistical analyses, with 4 reporting significant improvements. The commonly cited facilitators and barriers were communication and resources, respectively. CONCLUSION: The field of KT in SCI is in its infancy with only a few relevant publications. However, there is some evidence that KT interventions may change clinician behavior and improve patient outcomes. Future studies should ensure rigorous study methods are used to evaluate KT interventions.

Use of computer-aided three-dimensional prototyping to surgically assist in tooth autotransplantation.

Autotransplantation is a surgical technique in which a donor tooth belonging to the same individual is repositioned into a surgically prepared socket or site of previous tooth extraction. It is beneficial in patients with teeth affected by agenesis, trauma, significant caries, and in teeth in a non-restorable condition or prognostically poor due to other pathology. It is particularly useful in paediatric patients, as properly transplanted teeth have a vital periodontium that allows for continuous growth and functional adaptation leading to preservation of the alveolar ridge. Technological advances in rapid prototyping combined with three-dimensional (3D) computed tomography (CT) have the ability to revolutionise autotransplantation. Preoperative planning for atraumatic extraction of the donor tooth and precise preparation of the recipient site with a rapid prototyped surgical template of the donor tooth considerably reduces the extra-alveolar time, and also reduces manipulation of the root sheath and periodontal ligament, and related trauma. This case series demonstrates the efficient and successful autotransplantation of various types of teeth with the use of a rapid prototyped surgical template produced from 3D CT. The use of this technology is expected to refine the surgical technique and improve treatment outcomes.

Ten-year study of postoperative complications following dental extractions in patients with inherited bleeding disorders.

Dental extractions challenge the body's haemostatic mechanism. Postoperative bleeding from dental extraction can be prolonged, or even life threatening in patients with inherited bleeding disorders. Pre- and postoperative clotting factor replacements or systemic desmopressin (ddAVP) have been advocated at our institution to prevent bleeding complications in these patients. This study aimed to assess the postoperative bleeding rate in patients with inherited bleeding disorders that underwent dental extractions at our institution between 2003 and 2012. Patients with inherited bleeding disorders such as haemophilia A, haemophilia B, and von Willebrand's disease were included. Retrospective chart review was conducted. The result showed 53 extraction events occurred in 45 patients over the 10-year period. Ten out of 53 extraction events (18.9%) had postoperative bleeding requiring further factor replacement or ddAVP. Postoperative bleeding in one patient with mild haemophilia A was complicated by the development of inhibitors. Type and severity of bleeding disorder, bone removal, and use of a local haemostatic agent did not have any significant effect on postoperative bleeding. Despite the use of perioperative factors and desmopressin, the postoperative bleeding rates remain high for patients with inherited bleeding disorders. More studies are required to assess the safety and effectiveness of using local haemostatic control to achieve haemostasis following extractions.

Lack of a role of DNA methylation in tumor promoter 12-O-tetradecanoylphorbol-13-acetate-induced synthesis of ornithine decarboxylase messenger RNA in T24 cells.

Association of alteration in DNA methylation pattern in triggering 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced transcription of ornithine decarboxylase (ODC) gene in T24 cells was determined. In accord with our previous findings (Archiv. Biochem. Biophys., 262: 326-336, 1988), TPA treatment of T24 cells, cultured in serum-free medium, resulted in a dramatic (approximately 15-fold) increase in ODC activity which was accompanied by a proportional increase in hybridizable amount of ODC mRNA. Data from nuclear run-off transcription assay revealed that TPA-induced accumulation of ODC mRNA is the result of increased transcription initiation. Since DNA hypomethylation has been proposed to be a mechanism involved in the regulation of transcription of some gene(s), we examined the changes in the methylation patterns in the ODC gene isolated from the vehicle (ethanol)- and TPA-treated T24 cells. The autoradiograms resulting from the Southern blot analysis of DNA cleaved with several methylation-sensitive restriction endonucleases [e.g., HpaII, MspI, cfoI (HhaI), SalI, XhoI] exhibited no difference in methylation pattern of ODC gene in T24 cells. Also, a single or chronic application of TPA to either noninitiated or 7,12-dimethylbenz(a)anthracene-initiated mouse skin failed to alter DNA methylation pattern of ODC gene. Furthermore, the hypomethylation agent 5-azacytidine failed to induce ODC mRNA in T24 cells. These results indicate that TPA does not affect the methylation status of ODC gene and hypomethylation may not be sufficient for TPA-increased ODC gene transcription in T24 cells.

Expression of human chromosome 2 ornithine decarboxylase gene in ornithine decarboxylase-deficient Chinese hamster ovary cells.

Ornithine decarboxylase (ODC) belongs to a multigene family and some of these may very well be nonfunctional (pseudogenes). We isolated an ODC gene from a human chromosome 2-specific library and transfected the gene into ODC-deficient Chinese hamster ovary cells to directly demonstrate that this ODC gene is functional and ODC is essential for cell proliferation. After screening 2.5 X 10(5) plaques using a human ODC complementary DNA probe, a typical clone with a 5.4-kilobase insert was isolated and then cloned into the HindIII site of the pGem-1 vector. One (phODC 2B1) of these clones containing a 5.4-kilobase ODC gene insert was identified. Restriction enzyme analysis and partial sequencing data revealed that phODC 2B1 contained the full length protein-coding sequences but lacked first exon and 3'-polyadenylation sequences. Primer extension analysis indicated that human ODC mRNA has homologous sequences with the ODC gene from human chromosome 2. To determine that the chromosome 2 ODC gene is functional, ODC-deficient Chinese hamster ovary cells were transfected with the ODC expression vector (phSV2B1-neo) and several G418-resistant transfectants were isolated which expressed 70- to 400-fold more ODC activity than parental or wild-type Chinese hamster ovary cells. Furthermore, these stable transfectants exhibited a higher growth rate than wild-type cells. These results indicate that the ODC gene from human chromosome 2 encodes functional ODC protein, and ODC (and its product putrescine) is required for cell growth.

Serum prostate specific antigen levels in mice bearing human prostate LNCaP tumors are determined by tumor volume and endocrine and growth factors.

The ability of prostate-specific antigen (PSA) to predict tumor volume and stage in patients with prostate cancer would be improved if factors regulating its production and clearance were better defined. A thorough understanding of the pharmacokinetics (regulation of production, metabolism, and excretion) of PSA has been precluded, however, by the absence of an in vivo animal model. The purposes of this study are to develop a murine model for evaluating PSA pharmacokinetics in vivo and to assess factors that influence PSA production in vitro. The human prostate cancer cell line, LNCaP, was chosen because it is androgen sensitive and PSA positive. Although LNCaP cells are usually nontumorigenic when inoculated s.c. in athymic mice, coinoculation of 1 x 10(6) LNCaP cells with 1 x 10(6) human bone fibroblasts reliably produces PSA-secreting carcinomas. This LNCaP model provides accurate correlation between tumor volume and serum PSA levels (r = 0.94) and demonstrates that tumor volume and androgens are codeterminants of circulating PSA levels. Following castration, serum PSA levels decrease rapidly up to 8-fold and increase up to 20-fold following androgen supplementation, without detectable castration-induced tumor cell death or concomitant changes in tumor volume. Serum PSA levels increase 0.24 ng/ml/mm3 of tumor, which is approximately 5-fold less than that estimated for humans. Most likely this reduced PSA index (PSA:tumor volume ratio) results from a 7-fold faster clearance of PSA in athymic mice than in humans; other than this shorter half-life, PSA elimination in the murine model appears similar to that in humans, with both following first-order kinetics characteristic of a two-compartment model. Interestingly, following prolonged growth (greater than 21 days) in castrate hosts, LNCaP tumors are capable of adapting to an androgen-deprived environment whereby LNCaP tumors regain the ability to secrete PSA in amounts similar to the precastrate state. In LNCaP cells, androgens increase PSA mRNA levels 4-fold in vivo and in vitro. PSA mRNA expression is also altered by various growth factors. Changes in PSA production induced by androgens and growth factors do not always parallel changes in LNCaP cell growth rate induced by these factors, suggesting that PSA production occurs independently of cell growth rate and may be influenced by various interrelated factors, including hormonal and stromal milieu. Observations from this murine model suggest that androgens and tumor volume are independent determinants of serum PSA levels and imply that decreases in circulating PSA following antiandrogen therapy may not always reflect a corresponding reduction in tumor volume.

Autocrine regulation of prostate-specific antigen gene expression in a human prostatic cancer (LNCaP) subline.

Prostate-specific antigen (PSA), a M(r) 34,000 serine protease, is recognized as a useful marker for the detection and prognosis of patients with prostate cancer. Although serum PSA is an excellent prognostic indicator, an increasing number of factors were found to regulate the PSA expression of prostatic cancer cells, which include androgenic steroids, the growth factors (GFs) and the extracellular matrix. The purpose of this study is to define a novel protein factor that may be responsible for regulating PSA expression by androgen-independent (AI) human prostate cancer cells. We have established a LNCaP subline (C4) from a parental LNCaP tumor grown in a castrated host. The C4 subline overexpressed PSA mRNA and protein. Serum-free conditioned medium (CM) isolated from the C4 subline is able to stimulate PSA gene expression in parental LNCaP cells in a concentration-dependent manner. This autocrine PSA-inducing activity was found to be organ specific because CMs from other fibroblast cell lines (such as bone, prostate, kidney, and lung fibroblasts) and the CMs from several prostatic carcinoma cell lines (such as parental LNCaP, PC-3, DU-145) and a bladder transitional carcinoma cell line (WH) fail to exhibit similar activity. The activity of the CM from the C4 subline cannot be substituted by GFs such as TGF-alpha, TGF-beta, bFGF, HGF, KGF, or NGF; neuropeptide (bombesin/GRP); secondary messenger analogue (dibutyryl cAMP); beta 2-adrenergic agonist (isoproterenol); or alpha 1-adrenergic agonist (phenylephrine), indicating that the factor(s) may be a novel prostate-specific autocrine factor (PSAF). Both androgen and PSAF exhibit an additive effect on up-regulating PSA gene expression, suggesting that the signal transduction pathway elicited by PSAF may differ from that mediated by the androgen receptor. Further characterization of PSAF by heat, acid, and trypsin digestion revealed that the PSAF may be a protein factor with a unique amino acid composition. These observations suggest that a novel autocrine pathway mediated by PSAF may be responsible for the overexpression of PSA mRNA and protein in a human prostatic cancer cell line. The potential clinical significance of this factor will be discussed.

The dual impact of coxsackie and adenovirus receptor expression on human prostate cancer gene therapy.

In a recent paper, we reported a significant difference in coxsackie and adenovirus receptor (CAR) from several human bladder cancer cell lines that correlated with their sensitivities to adenoviral infection (Y. Li, R-C. Pong, J. M. Bergelson, M. C. Hall, A. I. Sagalowsky, C-P. Tseng, Z. Wang, and J. T. Hsieh, Cancer Res., 59: 325-330, 1999). In human prostate cancer, CAR protein is down-regulated in the highly tumorigenic PC3 cell line, which suggests that, in addition to its function as a viral receptor, CAR may have a pathophysiological role in prostate cancer progression. In this paper, we document that CAR does not merely enhance the viral sensitivity of prostate cancer cells but also acts as a tumor inhibitor for androgen-independent prostate cancer cells. Our data indicate that CAR is a potential therapeutic agent for increasing the efficacy of prostate cancer therapy.

Acceleration of human prostate cancer growth in vivo by factors produced by prostate and bone fibroblasts.

Prostate cancer, the most prevalent cancer affecting men, frequently metastasizes to the axial skeleton where it produces osteoblastic lesions with growth rates often exceeding that of the primary tumor. To evaluate the role of tumor cell-host stromal interaction and stromal specific growth factors (GFs) in prostate cancer growth and progression, we coinoculated athymic mice with human prostate cancer cells (LNCaP) and various nontumorigenic fibroblasts s.c. LNCaP tumor formation was most consistently induced by human bone (MS) fibroblasts (62%), followed by embryonic rat urogenital sinus mesenchymal (rUGM) cells (31%) and Noble rat prostatic fibroblasts (17%), but not by NIH-3T3, normal rat kidney, or human lung CCD16 fibroblasts. Carcinomas formed preferentially in male hosts, demonstrating in vivo androgen sensitivity. The human prostate component of these tumors was confirmed with immunohistochemical staining for prostate-specific antigen (PSA), Northern analysis for PSA expression, and Southern analysis for human repetitive Alu sequences. Elevations in serum PSA paralleled the histomorphological and biochemical findings. LNCaP and fibroblast cell-conditioned media (CM) was used to determine whether autocrine and paracrine mitogenic pathways exist between LNCaP and fibroblast cells in vitro, and various defined GFs were tested to identify possible active factors. Mitogenic assays revealed a 200-300% bidirectional stimulation between LNCaP and bone or prostate fibroblast-derived CM. Lung, normal rat kidney, and 3T3 fibroblast CM were not mitogenic for LNCaP cells. Among the purified GFs tested basic fibroblast growth factor (bFGF) was the most potent mitogen, stimulating LNCaP growth 180% in a concentration-dependent manner. Transforming growth factor alpha and epidermal growth factor were both minimally mitogenic. Coinoculation of LNCaP cells with a slowly absorbed matrix (Gelfoam) absorbed with bFGF or dialyzed and concentrated rUGM or MS CM was also capable of inducing LNCaP tumor formation in vivo. These observations illustrate that fibroblasts differentially modulate prostate cancer growth through the release of paracrine-mediated GFs, possibly including bFGF, and that tumor-stromal cell interactions play an important role in prostate cancer growth and progression.

The mechanism of the growth-inhibitory effect of coxsackie and adenovirus receptor (CAR) on human bladder cancer: a functional analysis of car protein structure.

The coxsackie and adenovirus receptor (CAR) is identified as a high-affinity receptor for adenovirus type 5. We observed that invasive bladder cancer specimens had significantly reduced CAR mRNA levels compared with superficial bladder cancer specimens, which suggests that CAR may play a role in the progression of bladder cancer. Elevated CAR expression in the T24 cell line (CAR-negative cells) increased its sensitivity to adenovirus infection and significantly inhibited its in vitro growth, accompanied by p21 and hypophosphorylated retinoblastoma accumulation. Conversely, decreased CAR levels in both RT4 and 253J cell lines (CAR-positive cells) promoted their in vitro growth. To unveil the mechanism of action of CAR, we showed that the extracellular domain of CAR facilitated intercellular adhesion. Furthermore, interrupting intercellular adhesion of CAR by a specific antibody alleviates the growth-inhibitory effect of CAR. We also demonstrated that both the transmembrane and intracellular domains of CAR were critical for its growth-inhibitory activity. These data indicate that the cell-cell contact initiated by membrane-bound CAR can elicit a negative signal cascade to modulate cell cycle regulators inside the nucleus of bladder cancer cells. Therefore, the presence of CAR cannot only facilitate viral uptake of adenovirus but also inhibit cell growth. These results can be integrated to formulate a new strategy for bladder cancer therapy.

Application of a tumor suppressor (C-CAM1)-expressing recombinant adenovirus in androgen-independent human prostate cancer therapy: a preclinical study.

Recently, we demonstrated that an androgen-regulated cell adhesion molecule, C-CAM, acts as a tumor suppressor in prostate cancer development. In this study, we further explored the possibility of applying C-CAM as a potential agent for developing prostate cancer gene therapy using an adenoviral delivery system. We found that prostate cancer cells, in general, were sensitive to adenoviral infection. In vitro characterization indicated that C-CAM1 protein was detected only in C-CAM1 adenovirus-infected cells but not in antisense control virus-infected cells, and the levels of expression showed dose dependency. Because of the stability of the protein, C-CAM expression in viral-infected cells appeared to be a long-lasting event, indicating that C-CAM may be superior to many other known tumor suppressors that have a short protein half-life. Most importantly, the delivery of a single dose of C-CAM adenovirus was able to repress the growth of PC-3-induced tumors in nude mice for at least 3 weeks. Taken together, these data indicate that C-CAM is a potential candidate for human prostate cancer therapy.

Tumor suppressive role of an androgen-regulated epithelial cell adhesion molecule (C-CAM) in prostate carcinoma cell revealed by sense and antisense approaches.

We recently demonstrated that C-CAM, an epithelial-cell adhesion molecule of the immunoglobulin supergene family, could be regulated by androgen and might act as a growth repressor during differentiation of the prostatic epithelium. To define the role of C-CAM in prostatic tumorigenesis, a tumorigenic human prostatic cancer cell line, PC-3, was transfected with an expression plasmid containing C-CAM1 (a C-CAM isoform). Transfected clones showed significantly lower growth rates, reduced anchorage-independent growth, and less tumorigenicity in vivo than control cells. Furthermore, transfection of an antisense vector into a nontumorigenic prostatic epithelial cell line, NbE, resulted in tumor formation in nude mice. Sublines derived from these NbE-induced tumors had lower levels of C-CAM than did control cells. These data suggest that C-CAM1 can function as a tumor suppressor in prostate tumorigenesis.

Epidermal growth factor receptor-mediated autocrine and paracrine stimulation of human transitional cell carcinoma.

Stromal-epithelial interactions may play a key role in tumor growth and metastasis. We have established a model to study the cellular and molecular basis of this paracrine interaction both in vivo and in vitro using a human transitional cell carcinoma cell line (WH). s.c. coinoculation of 1 x 10(6) WH cells with 1 x 10(6) nontumorigenic fetal rat urogenital sinus mesenchymal (rUGM) cells in athymic mice accelerated carcinoma growth 20 times faster than isolated WH cell inoculations and 4 times faster than coinoculations of the same number of NIH-3T3 or human bladder fibroblasts. Characterization of these chimeric tumors with immunohistochemical and DNA dot-blot analyses documented their predominantly human component. To evaluate the underlying mechanisms involved in this paracrine-mediated in vivo tumor growth acceleration, Northern analyses for growth factors (GFs) and extracellular matrix (ECM) expression in the different cell lines, as well as in vitro mitogenic assays, were performed. Northern analysis revealed basic fibroblast growth factor, transforming growth factor alpha, and epidermal growth factor receptor expression by WH cells but not rUGM cells; ECM components (fibronectin and collagens I and IV) were expressed only in the fibroblast cell lines. Cell type-specific paracrine growth factors are produced by cultured stromal and epithelial cells with a 2-3-fold bidirectional increase in WH and rUGM cell growth when cultured with reciprocal cell-type conditioned medium. An autocrine growth loop was observed for WH but not rUGM cells. WH cell growth is stimulated in vitro by low concentrations of transforming growth factor alpha and epidermal growth factor, while rUGM cell growth is stimulated 3-fold by basic fibroblast growth factor. Antiepidermal growth factor receptor antibodies completely inhibited autocrine and paracrine pathways stimulating WH cell growth, while anti-basic fibroblast growth factor antibodies had no inhibitory effect. These observations suggest that autocrine and paracrine growth factor stimulation of WH bladder carcinoma cell growth is most likely mediated by an epidermal growth factor receptor-related pathway. The predominant expression of ECM by fibroblasts in this model suggests that stromal cell ECM components may modulate tumor cell growth and angiogenesis possibly through mechanisms involving cellular adhesion, chemotaxis, or growth factor action.

Consistent expression of an epithelial cell adhesion molecule (C-CAM) during human prostate development and loss of expression in prostate cancer: implication as a tumor suppressor.

Cell adhesion molecules have been suggested to function as tumor suppressor molecules. We have been studying one of the epithelial cell adhesion molecules (C-CAM), which belongs to the immunoglobulin gene superfamily. Transfection of a C-CAM cDNA expression vector into a highly tumorigenic human prostate cancer cell line (PC-3) suppresses tumor formation in nude mice. Alternatively, reducing C-CAM expression levels in the nontumorigenic rat prostate epithelial cell line NbE by the antisense expression vector markedly increases tumorigenicity of NbE cells in nude mice. These results suggest that C-CAM may be a tumor suppressor in prostate cancer. In this study, we examined the relationship between C-CAM expression during human prostate development and neoplastic progression by immunohistochemical staining of frozen sections. C-CAM predominantly localized on the plasma membrane of the basal cell layer in both the fetal and normal adult prostate gland. However, an overall decreased staining was seen in benign prostatic hyperplasia and high grade prostatic intraepithelial neoplasia. Furthermore, C-CAM was not detected in prostate carcinomas. Thus, a decrease in C-CAM expression may be an early event in hyperplastic/neoplastic transformation. These observations support the suggestion that C-CAM is a tumor suppressor in prostate cancer progression.

Expression of the protooncogene bcl-2 in the prostate and its association with emergence of androgen-independent prostate cancer.

The significance of apoptosis in relation to the development and progression of prostate cancer remains largely undefined. bcl-2 is an oncogene that functions by overriding apoptosis. bcl-2 expression was localized to the basal epithelial cells in the normal human prostate with the use of immunohistochemistry. Androgen-dependent and androgen-independent prostate carcinomas were evaluated immunohistochemically for bcl-2 expression. bcl-2 was undetectable in 13 of 19 cases of androgen-dependent cancers. In contrast, androgen-independent cancers displayed diffuse, high levels of bcl-2 staining (P < 0.01). In rats, steady-state levels of bcl-2 mRNA, assessed by S1 assays, reached maximum levels 10 days following castration. Addition of exogenous testosterone with, or without, flutamide demonstrated that the increased bcl-2 mRNA resulted from androgen ablation. Our findings indicate that bcl-2 expression is augmented following androgen ablation and is correlated with the progression of prostate cancer from androgen dependence to androgen independence.

Adenovirus-mediated expression of PML suppresses growth and tumorigenicity of prostate cancer cells.

Our previous studies demonstrated that the promyelocytic leukemia gene, PML, encodes a growth and transformation suppressor. Overexpression of PML inhibits cancer cell growth in vitro and in vivo. In this study, we further explored the possibility of applying PML as a potential agent for developing prostate cancer gene therapy using an adenovirus delivery system. We have constructed and produced the recombinant PML-adenovirus, Ad-PML, in which the full-length PML cDNA is driven by the strong cytomegalovirus promoter. In LNCaP, DU145, and PC-3 prostate cancer cell lines, an infection efficiency of 90% can be achieved at a concentration of 2, 10, and 100 multiplicity of infection (MOI), respectively. Western blotting and immunofluorescence staining demonstrated that the AD-PML-infected cells expressed a high level of PML protein. The protein expression peaked at days 3-4 postinfection, and a detectable level of PML was found at day 18 after viral infection. To test the effect of Ad-PML on the growth of prostate cancer cells, the DU145 and LNCaP cells were infected with 10 and 2 MOI of Ad-PML. We found that the growth rate of the Ad-PML-infected DU145 and LNCaP cells were significantly inhibited. A tumorigenicity test in nude mice showed that the Ad-PML-treated DU145 cells failed to form tumors. Most importantly, direct injection of Ad-PML into DU145-induced tumors was able to repress tumor growth in nude mice by 64%. Taken together, these data indicate that PML is a tumor growth suppressor in prostate cancer and that Ad-PML may be a potential candidate for human prostate cancer therapy.

Suppression of human bladder cancer growth by increased expression of C-CAM1 gene in an orthotopic model.

Recently, we demonstrated that an immunoglobulin-like cell adhesion molecule, C-CAM, acts as a tumor suppressor in prostate cancer. It is known that C-CAM is expressed in many epithelial cell types. In this study, we tested the possibility that C-CAM may also suppress bladder cancer progression. We used an orthotopic tumor model, which provides a relevant organ condition for examining the interaction between primary tumor cells and their microenvironment; this interaction has a critical impact on the behavior of carcinoma. We constructed a recombinant adenovirus expressing C-CAM1 (an isoform of C-CAM) and infected the 253J B-V cell line, a tumorigenic human bladder carcinoma subline. In vitro, C-CAM1 protein was detected in C-CAM1 adenovirus-infected cells but not in antisense control virus-infected cells, and the levels of expression showed dose dependency. When these cells were injected orthotopically in nude mice, we found that the increased expression of C-CAM1 in the 253J B-V cells repressed the growth of 253J B-V-induced tumors. Taken together, these data indicate that C-CAM1 is a potent tumor suppressor in human bladder cancer.

Loss of adenoviral receptor expression in human bladder cancer cells: a potential impact on the efficacy of gene therapy.

There is great interest in the development of gene therapeutic strategies for the treatment of benign and malignant diseases. Recombinant adenovirus has a wide spectrum of tissue specificity and is an efficient vector delivery system. Successful gene delivery, however, requires viral entry into the target cells via specific receptor-mediated uptake. Recently, a cDNA clone (the coxsackie and adenovirus receptor [CAR]) encoding a 46-kDa protein was identified as the receptor for group C adenovirus (e.g., adenovirus type 2 and 5). Currently, little is known regarding the expression of adenoviral receptor in normal tissue and cancer. In this paper, we have documented a significant difference in viral receptor levels that may be due to transcriptional regulation of the CAR gene in several human bladder cancer cell lines. The differences in viral receptor levels in these cells correlated with their sensitivity to viral infection. Transfection of receptor-negative cell line with CAR cDNA led to increased virus binding and increased susceptibility to adenovirus-mediated gene delivery. Our results demonstrate that the expression of adenoviral receptor is variable among human bladder cancer cells. This variability may have a significant impact on the outcome of adenovirus-based gene therapy.

Loss of DAB2IP in RCC cells enhances their growth and resistance to mTOR-targeted therapies.

Targeted therapies using small-molecule inhibitors (SMIs) are commonly used in metastatic renal cell cancer (mRCC) patients; patients often develop drug resistance and eventually succumb to disease. Currently, understanding of mechanisms leading to SMIs resistance and any identifiable predictive marker(s) are still lacking. We discovered that DAB2IP, a novel Ras-GTPase-activating protein, was frequently epigenetically silenced in RCC, and DAB2IP loss was correlated with the overall survival of RCC patients. Loss of DAB2IP in RCC cells enhances their sensitivities to growth factor stimulation and resistances to SMI (such as mammalian target of rapamycin (mTOR) inhibitors). Mechanistically, loss of DAB2IP results in the activation of extracellular signal-regulated kinase/RSK1 and phosphoinositide-3 kinase/mTOR pathway, which synergizes the induction of hypoxia-inducible factor (HIF)-2α expression. Consequently, elevated HIF-2α suppresses p21/WAF1 expression that is associated with resistance to mTOR inhibitors. Thus combinatorial targeting both pathways resulted in a synergistic tumor inhibition. DAB2IP appears to be a new prognostic/predictive marker for mRCC patients, and its function provides a new insight into the molecular mechanisms of drug resistance to mTOR inhibitors, which also can be used to develop new strategies to overcome drug-resistant mRCC.

Induction of apoptosis and G2/M cell cycle arrest by DCC.

The Deleted in Colorectal Cancer gene (DCC) encodes a cell surface receptor that belongs to the Ig superfamily. Inactivation of the DCC gene has been implicated in human tumor progression. However, little is known about the biological function of the DCC protein. In the present study, we demonstrated that expression of DCC activated caspase-3 and programmed cell death, or induced G2/M cell cycle arrest in tumor cells. In some cell lines, apoptosis was evident within 24 h of DCC expression. Timing of the appearance of apoptotic cells coincided with that of the cleavage of poly (ADP-ribose) polymerase, a substrate of caspase-3. Expression of the apoptosis inhibitory gene Bcl-2 was not able to abrogate the DCC-induced apoptosis. In the G2/M cycle arrest cells, cdk1 activity was inhibited. Our results suggest that the DCC protein may transduce signals resulting in activation of caspases or inhibition of Cdk1. These data provide a possible mechanism by which DCC suppresses tumorigenesis.