Evaluation of the Utility of Liquid-based Cytology, Cell-blocks, and Flow Cytometric Immunophenotyping on Endobronchial Ultrasound-guided Transbronchial Needle Aspiration Samples in the Diagnosis of Sarcoidosis.

BACKGROUND: There is little information on the value of different processing methods for samples obtained during endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA) in suspected sarcoidosis. We evaluated the role of conventional smears, liquid-based cytology (LBC), cell-blocks and flow cytometric immunophenotyping in the diagnosis of sarcoidosis using EBUS-TBNA samples. METHODS: This was a prospective study of consecutive EBUS-TBNA samples from clinically suspected cases of sarcoidosis. In addition to conventional smears, we prepared LBC smears, cell-blocks, and performed flow cytometric evaluation of the CD4:CD8 ratio. The final diagnosis of sarcoidosis was made based on the relevant clinical details and laboratory investigations including the results of transbronchial and endobronchial biopsies (TBLB and endobronchial biopsy). RESULTS: We included 60 subjects [mean age: 45.2 y; 29 (48.3%) men]. The sensitivity of conventional smears, LBC, and cell-blocks for diagnosing sarcoidosis was found to be 75.5%, 37.8%, 35%, respectively, when used alone. However, on combining conventional and LBC smears, the sensitivity increased to 84.4% and on combining all three techniques, the sensitivity was 86.7%. The CD4:CD8 ratio on flow cytometric immunophenotyping of EBUS-TBNA samples ranged from 0 to 11.5 with a mean of 3.17±2.78 in confirmed cases of sarcoidosis and 70% of these cases had CD4:CD8 ratio of more than 2. CONCLUSION: Cell-blocks and liquid-based preparations add to the yield of conventional preparation of EBUS-TBNA samples in the diagnosis of sarcoidosis. A combination of conventional and LBC works well in detecting almost 85% of the cases of sarcoidosis. Higher CD4:CD8 ratio favors a diagnosis of sarcoidosis.

Amyloidosis secondary to chronic pulmonary aspergillosis: Case report and a systematic review of literature.

Secondary amyloidosis results from the deposition of abnormally folded proteins in body organs due to chronic inflammatory disorders. Kidneys are the most commonly affected organ and manifest as nephrotic syndrome with or without renal failure. Chronic pulmonary aspergillosis (CPA) is a chronic infection of lung parenchyma affecting those with an underlying structural lung disease. Herein, we present a case of CPA where the initial manifestation was that of nephrotic syndrome due to renal amyloidosis. We also perform a systematic review for studies describing secondary amyloidosis due to CPA.

Monitoring treatment response in chronic pulmonary aspergillosis: role of clinical, spirometric and immunological markers.

OBJECTIVES: The treatment response in chronic pulmonary aspergillosis (CPA) is usually assessed based on the improvement in clinical and imaging findings. Herein, we evaluate serum Aspergillus fumigatus-specific IgG, serum galactomannan, weight change, and lung function for assessing treatment response in subjects with CPA. METHODS: We categorized treatment response as favourable (improved or stable clinical response with radiologically improved or stable disease) or unfavourable (worsening of symptoms or radiological progression) after 6 months of treatment with antifungal azoles. We measured A. fumigatus-specific IgG, serum galactomannan, weight, and lung function at baseline, 3 months, and 6 months in those with favourable and unfavourable treatment response. RESULTS: One hundred and twenty-six consecutive treatment-naïve subjects (53.2% (67/126) males; mean ± SD age, 42.3 ± 14.7 years) with CPA were included. One hundred and six and 20 were classified as having favourable and unfavourable response, respectively. After 6 months of treatment, the decline in serum A. fumigatus-specific IgG (n = 119) was similar in those with favourable or unfavourable response (mean ± SD, -26.3 ± 45.5 mgA/L vs. -3.4 ± 65.6 mgA/L; p 0.20). There was no significant change in the serum galactomannan (favourable vs. unfavourable: mean ± SD, -0.11 ± 2.8 vs. -0.62 ± 2; p 0.92) or FEV1 (favourable vs. unfavourable: mean ± SD, 24 ± 250 mL vs. -62 ± 154 mL; p 0.19) after 6 months of treatment. There was significant loss of weight (mean ± SD, -2.5 ± 4.5 kg) in subjects with unfavourable response. CONCLUSION: Serum A. fumigatus-specific IgG and serum galactomannan inconsistently decrease following treatment and may not be useful indicators for monitoring treatment response in CPA. Similarly, there is little change in pulmonary function following treatment. A gain in body weight is seen in those with favourable response.

Evolving epidemiology of lung cancer in India: Reducing non-small cell lung cancer-not otherwise specified and quantifying tobacco smoke exposure are the key.

BACKGROUND: Adenocarcinoma is the most prevalent histological type of lung cancer (LC) in developed countries while squamous cell carcinoma (SqCC) has so far been the most common type at our center. Herein, we report our continued assessment of the epidemiological trend of LC aimed at determining any change in the histological distribution. METHODS: Retrospective analysis involving all consecutive newly diagnosed LC patients over a 4-year period (March 2011-February 2015). Demographic characteristics, histology, and staging data for current data set were compared with our previously published data (2008-2011). As before, smoking index (SI) was used to group patients as never (SI = 0), light (SI = 1-100), moderate (SI = 101-300), and heavy (SI ≥301) smokers. RESULTS: Majority of 1301 patients had advanced disease (Stages IIIB = 30.1%; IV = 53.3%), were males (82.3%) and current/ex-smokers (76.9%). Adenocarcinoma and SqCC (36.4% each) were equally prevalent. As compared to our previous study, adenocarcinoma increased (36.4% vs. 27.5%) and nonsmall cell lung cancer-not otherwise specified (NSCLC-NOS) decreased (5.1% vs. 10.9%) significantly (P < 0.001). The current study had more heavy smokers (68.3% vs. 61.1%; P = 0.013) and median SI was also higher (500 vs. 400; P = 0.001). Among SI-based groups, significant differences were observed for age, gender, body mass index, histology, TNM stage, and metastatic disease distribution. CONCLUSION: Reduction in NSCLC-NOS has led to adenocarcinoma and SqCC being equally prevalent at our center in North India despite an increase in heavy smokers. Accurate histological NSCLC subtyping is necessary for optimal epidemiological assessment.

Meta-analysis of Indian studies evaluating adenosine deaminase for diagnosing tuberculous pleural effusion.

OBJECTIVE: To determine the diagnostic accuracy of pleural fluid adenosine deaminase (ADA) in diagnosing tuberculous pleural effusion (TPE) among Indian patients using systematic review and meta-analysis. DESIGN: The PubMed, Embase, IndMED and Cochrane databases and other relevant publications were searched to identify Indian studies evaluating the sensitivity and specificity of ADA in diagnosing TPE. Pooled diagnostic accuracy measures and 95% confidence intervals (95%CI) were generated using a bivariate random-effects model, and examined using forest plots and hierarchical summary receiver operating characteristic (HSROC) curves. RESULTS: Forty publications with 3524 patients were studied. Pooled sensitivity, specificity and diagnostic odds ratio estimates were high (0.94, 95%CI 0.89-0.96; 0.89, 95%CI 0.83-0.93; and 119.85, 95%CI 48.35-297.08, respectively). The area under the HSROC curve was 0.966. The most common ADA threshold was 40 international units (IU)/l in 18 studies. Pooled positive and negative likelihood ratios for thresholds between 38 and 42 IU/l were respectively 6.80 (95%CI 4.18-11.07) and 0.06 (95%CI 0.03-0.11). There was no clear change in diagnostic performance with increasing ADA thresholds. Multivariate meta-regression did not reveal any factor that significantly influenced the substantial heterogeneity between studies. CONCLUSION: Pleural fluid ADA has good diagnostic accuracy for TPE in Indian patients, and appears more useful at excluding TPE at a threshold value of around 40 IU/l.

Allergic bronchopulmonary aspergillosis complicating Swyer-James-Macleod's syndrome: case report and review of literature.

Allergic bronchopulmonary aspergillosis (ABPA) is a pulmonary disorder that results from immune responses mounted against antigens of Aspergillus fumigatus, resulting in non-specific respiratory symptoms and structural lung damage. Classically defined in individuals suffering from bronchial asthma and cystic fibrosis, ABPA has recently been described in other lung diseases including COPD, pulmonary tuberculosis, idiopathic bronchiectasis and others. Herein, we report the first case of ABPA complicating Swyer-James-Macleod's syndrome that was successfully treated with oral antifungal therapy.

The radiosensitizing effect of the aurora kinase inhibitors, ENMD-2076, on canine mast cell tumours in vitro.

ENMD-2076 is an aurora kinase inhibitor that also has multi-target tyrosine kinase inhibitor properties. In this study, the mRNA and the protein expression of aurora-A and aurora-B were evaluated in three canine mast cell tumour cell lines. Dose-dependent cytotoxicity was seen in the cells treated, and it affected the cell cycle with cells in the G2/M phase being selectively killed. The cells were also evaluated for radiosensitivity with/without ENMD-2076, and radiosensitization was seen after 3 Gy and 6 Gy exposures with ENMD-2076 for 48 h. Protein expression of caspase-3 was gradually increased, and the expression intensity was highest at 24 h post irradiation in cells without ENMD-2076 treatment, which indicates that radiation exposure with ENMD-2076-induced cell death faster than radiation treatment alone. Our study results suggest the potential usefulness of treating canine mast cell tumours with aurora kinase inhibitors alone or in conjunction with radiation therapy.

Role of inhaled amphotericin in allergic bronchopulmonary aspergillosis.

Allergic bronchopulmonary aspergillosis (ABPA) is an immunological pulmonary disorder caused by immune reactions mounted against the ubiquitous fungus Aspergillus fumigatus. The disease clinically manifests with poorly controlled asthma, hemoptysis, systemic manifestations like fever, anorexia and weight loss, fleeting pulmonary opacities and bronchiectasis. The natural course of the disease is characterized by repeated episodes of exacerbations. Almost 30-40% of the patients require prolonged therapy, which currently consists of corticosteroids and anti-fungal azoles; both these agents have significant adverse reactions. Amphotericin B administered via the inhaled route can achieve a high concentration in the small airways with minimal systemic side-effects. Nebulized amphotericin B has been used in the management of invasive pulmonary aspergillosis. The aim of this review is to study the utility of inhaled amphotericin in ABPA.

Kaposi's sarcoma-associated herpesvirus glycoproteins B and K8.1 regulate virion egress and synthesis of vascular endothelial growth factor and viral interleukin-6 in BCBL-1 cells.

Kaposi's sarcoma-associated herpesvirus (KSHV) viral glycoproteins play important roles in the infectious life cycle and have been implicated in KSHV-associated endothelial cell transformation, angiogenesis, and KS-induced malignancies. KSHV-associated primary effusion lymphomas (PELs) secrete high levels of vascular endothelial growth factor (VEGF) and viral interleukin-6 (vIL-6) in vitro and VEGF, vIL-6, and basic-fibroblast growth factor (b-FGF) in mouse xenografts. KSHV-encoded glycoproteins B (gB) and K8.1 stimulate VEGF secretion, most likely mediated by direct or indirect binding to cell surface receptors, including the gB-specific alphaVbeta3 and alpha3beta1 integrins. In this study, the short interfering RNA (siRNA)-mediated inhibition of either gB or K8.1 transcription by anti-gB or -K8.1 siRNAs caused a substantial reduction in virion egress and a decrease in both vIL-6 and VEGF production. Similarly, the treatment of BCBL-1 cells with anti-gB or anti-K8.1 antibodies caused a substantial reduction in vIL-6 and VEGF production. Codon-optimized versions of either wild-type gB, mutant gB having the RGD amino acid motif changed to RAA, or K8.1 efficiently rescued virion egress and VEGF and vIL-6 production. These results suggest that the binding of gB via its RGD motif to integrin receptors was not responsible for the observed gB-associated regulation of VEGF and vIL-6 transcription. Conditioned medium collected from BCBL-1 cells transfected with anti-gB and anti-K8.1 siRNAs or treated with anti-gB and anti-K8.1 antibodies exhibited a significantly reduced ability to induce the formation of the capillary network of endothelial cells compared to the ability of medium from mock-infected BCBl-1 cells. Furthermore, medium obtained from BCBL-1 cells expressing smaller amounts of gB and K8.1 produced a substantial reduction in endothelial cell migration in a vertical migration assay compared to that of control medium containing wild-type levels of gB and K8.1. These results suggest a functional linkage between gB/K8.1 synthesis and VEGF/vIL-6 transcriptional regulation via paracrine and/or autocrine signaling pathways.

Structure-function studies of the functional and binding epitope of the human 37 kDa laminin receptor precursor protein.

Expression of the 37 kDa laminin receptor precursor protein (37LRP) correlates directly with increased invasiveness and the metastatic potential of tumors. The 37LRP matures to a 67 kDa protein which facilitates the binding of cancer cells to basement membranes. The palindrome peptide sequence LMWWML, corresponding to the 173-178-residue stretch of the human 37LRP sequence, has been identified as the laminin-1-binding site. Peptides from 37LRP of species that contain this palindrome-bind laminin-1 with high affinity. Nuclear magnetic resonance (NMR) conformational studies have been undertaken on a synthetic 15-residue peptide (KGAHSVGLMWWMLAR) containing the palindrome to establish the structural basis of this activity. To further correlate the structural data with laminin-1-binding function, analogous structural studies were conducted for a similar peptide (RGKHSIGLIWYLLAR) lacking the palindrome, originating from 37LRP sequence of Saccharomyces cerevisiae and exhibiting low laminin-1-binding affinity. Finally, in vitro cell invasion assays were performed to investigate the possibility that the laminin-1-binding affinity of the peptides influences their inhibitory activity.

Growth factor regulation of secreted matrix metalloproteinase and plasminogen activators in prostate cancer cells, normal prostate fibroblasts and normal osteoblasts.

We assessed the relative levels of secreted matrix metalloproteinases (MMPs) and plasminogen activators (PAs) in PC-3 cells, prostate fibroblasts and osteoblasts in the presence and absence of VEGF, TGF beta1 and bFGF. Fibroblasts and osteoblasts secreted more MMPs -1 and -2 than did PC-3 cells, while PC-3 s contributed the majority of PAs. MMP-1 expression was downregulated by transforming growth factor beta-1 (TGF beta1) treatment in prostate fibroblasts and upregulated by basic fibroblast growth factor (bFGF) in both stromal lines. In PC-3 cells, TGF beta1 and bFGF increased urokinase plasminogen activator secretion. TGF beta1 decreased tissue plasminogen activator secretion in all cell lines. Prostate cancer cells associated with fibroblasts or osteoblasts have a variety of MMPs and PAs to facilitate matrix degradation.

Inhibition of murine prostate tumor growth and activation of immunoregulatory cells with recombinant canarypox viruses.

BACKGROUND: Immunization with modified tumor cells carrying recombinant immunomodulatory genes is being explored as cancer immunotherapy. In this study, we examine whether canarypox ALVAC viruses carrying immunostimulatory cytokine genes (granulocyte-macrophage colony-stimulating factor, interleukin 2, interleukin 12, and tumor necrosis factor-alpha) can induce antitumor immunity (to rechallenge) in the RM-1 model of a highly aggressive, weakly immunogenic murine prostate cancer. METHODS: For antitumor activity studies, RM-1 murine prostate cancer cells were infected with the parental ALVAC virus or one or two recombinant ALVAC-cytokine viruses and then injected into male C57BL/6 mice. For rechallenge studies, other mice were first given an injection subcutaneously with irradiated (nonproliferating) recombinant ALVAC-infected RM-1 cells and then (10 days later) with untreated RM-1 cells. For the determination of which immune cells were required for antitumor activity, mice were immunodepleted of CD4, CD8, or natural killer (NK) NK1.1 cells with the corresponding monoclonal antibodies and were then given an injection of ALVAC-cytokine-infected RM-1 cells. For all experiments, tumor outgrowth and animal survival were monitored. RESULTS: After subcutaneous injection into mice, RM-1 cells infected with one (except ALVAC-interleukin 2) or two ALVAC-cytokine recombinants had statistically significantly greater antitumor activity than RM-1 cells infected with parental ALVAC (P<.001 for all; two-sided test). The antitumor activity of RM-1 cells infected with any two ALVAC-cytokine recombinants was greater than, but not statistically significantly different from, that of RM-1 cells infected with any one ALVAC-cytokine recombinant. NK1.1 cells were necessary for antitumor activity, but tumor-specific CD4(+) regulatory T cells were also induced that inhibited CD8(+) RM-1-specific cytotoxic T cells, resulting in the lack of immunity to a rechallenge by RM-1 cells. DISCUSSION: Canarypox viruses can transfer immunostimulatory cytokine genes into RM-1 prostate cancer cells. When such cells were injected into mice, the cytokines induced an antitumor response against this highly aggressive, weakly immunogenic tumor. This response, however, did not protect the mouse against a rechallenge with RM-1 cells because suppressor CD4(+) T cells were induced that inhibited tumor-specific CD8(+) cytotoxic T cells.

Dietary 4-HPR suppresses the development of bone metastasis in vivo in a mouse model of prostate cancer progression.

The effects of the synthetic retinoid N-(4-hydroxyphenyl) retinamide (4-HPR) on prostate cancer metastasis in vivo were evaluated in the mouse prostate reconstitution (MPR) model. MPRs were produced by infection of either heterozygous (+/-) or nullizygous (-/-) p53-mutant fetal prostatic epithelial cells with the recombinant retrovirus Zipras/myc 9. Previous studies have documented that loss of p53 function potentiates metastasis in this model system. MPRs were grafted into homozygous (+/+) p53 male mice, fed a 4-HPR containing diet or a control diet and maintained until the status of tumor progression dictated sacrifice. Under these experimental conditions, treatment with 4-HPR did not have a significant effect on primary tumor wet weight for either p53 +/- or p53 -/- MPRs. For, p53 +/- MPRs the animals fed the 4-HPR diet had a slight improvement in survival and a significant reduction in the number of mesenteric metastases (P = 0.0477, t-test). Notably, in p53 +/- MPRs the incidence of metastasis to lumbar spine and sternum was 92% in the control animals compared to 54% in the 4-HPR treated animals (P = 0.035, chi2-test). In p53 -/- MPRs there was a trend toward a reduction in the number of soft tissue metastases to lung and liver in the 4-HPR group relative to the control diet group and a statistically significant reduction in the incidence of metastasis to bone was demonstrated in that 50% of control animals versus 30% of 4-HPR treated p53 -/- animals harbored bone metastases (P = 0 < 0.05, chi2-test). Cell lines were established from portions of the primary tumor and from selected metastatic deposits in each experimental group. Clonal analysis, by retroviral integration pattern, indicated increased clonal diversity in both the primary tumors and metastasis-derived cell lines from 4-HPR treated animals relative to the control animals. In vitro treatment with 4-HPR did not reveal discriminating differences between cell lines derived from primary tumors and bone metastases or control and treatment groups in regard to growth arrest or apoptotic responses. Overall these studies indicate limited anti-tumor and anti-metastatic activity in this highly aggressive in vivo mouse model of prostate cancer, yet 4-HPR treatment significantly suppressed the development of bone metastases in p53 +/- and p53 -/- MPRs revealing a novel and potentially clinically useful activity of this retinoid.

Novel regulation of type IV collagenase (matrix metalloproteinase-9 and -2) activities by transforming growth factor-beta1 in human prostate cancer cell lines.

The type IV collagenases/gelatinases matrix metalloproteinase-2 (MMP-2) and MMP-9 play a variety of important roles in both physiological and pathological processes and are regulated by various growth factors, including transforming growth factor-beta1 (TGF-beta1), in several cell types. Previous studies have suggested that cellular control of one or both collagenases can occur through direct transcriptional mechanisms and/or after secretion through proenzyme processing and interactions with metalloproteinase inhibitors. Using human prostate cancer cell lines, we have found that TGF-beta1 induces the MMP-9 proenzyme; however, this induction does not result from direct effects on gene transcription but, instead, through a protein synthesis-requiring process leading to increased MMP-9 mRNA stability. In addition, we have examined levels of TGF-beta1 regulation of MMP-2 in one prostate cancer cell line and found that TGF-beta1 induces higher secreted levels of this collagenase through increased stability of the secreted 72-kDa proenzyme. These results identify two novel nontranscriptional pathways for the cellular regulation of MMP-9 and MMP-2 collagenase gene expression and activities.

Neuropeptides induce Mr 92,000 type IV collagenase (matrix metalloprotease-9) activity in human prostate cancer cell lines.

The type IV collagenases matrix metalloprotease (MMP)-2 and MMP-9 are linked with a wide array of biological activities, including tumor invasion, metastasis, and angiogenesis. Here, we report that neuropeptide hormones, which are present in prostatic adenocarcinomas, can stimulate secreted activity of MMP-9 in human prostate cancer cell lines. Northern blotting analyses demonstrated that neuropeptide stimulation lead to elevated mRNA levels of MMP-9 but not MMP-2. Further assays of MMP-9 promoter activation and a nuclear run-off indicated that neuropeptide induction of MMP-9 expression occurs at the level of transcription. These data indicate that neuropeptides can regulate MMP activity, which, in turn, could facilitate prostate cancer progression.

Requirement for matrix metalloproteinase-9 (gelatinase B) expression in metastasis by murine prostate carcinoma.

Although a number of effective therapies are available for localized prostate cancer, metastatic prostate cancer is difficult to treat and impossible to cure. Identification of the gene products that enable a prostatic carcinoma cell to metastasize should facilitate an understanding of the processes leading to metastasis. To characterize the contribution of matrix metalloproteinase-9 (MMP-9, gelatinase B or the 92-kd type IV gelatinase/collagenase) to the development of metastasis in prostate cancer, we reduced MMP-9 expression in metastatic murine prostatic carcinoma cells using a ribozyme. The ribozyme transfected cells had lower basal levels of MMP-9 as well as decreased levels after stimulation by transforming growth factor-beta or phorbol 12-myristate 13-acetate when compared with the parental cells or with control transfectants. The cells with down-regulated MMP-9 were unable to form lung colonies in the experimental metastasis assay, whereas the controls and parental cells readily formed metastases. All cell types readily formed tumors after injection and down-regulation of MMP-9 did not adversely affect the rate of tumor growth. Thus, MMP-9 expression is required for hematogenous metastasis in a murine prostate model system raising the possibility that it may play an equivalent role in human prostate cancer.

Transforming growth factor beta1 stimulates contrasting responses in metastatic versus primary mouse prostate cancer-derived cell lines in vitro.

Tumor progression to the stage of metastasis may result in part from the selection of certain primary tumor cell clones which are phenotypically competent for survival, invasion, and growth at secondary sites. Selection for traits such as loss of growth inhibitory responses, acquisition of increased adhesiveness, increased local immunosuppression, and enhanced motility and collagenase activities likely contribute to cancer progression and may be regulated through the action of growth factors. The transforming growth factors (TGF-beta) family of growth factors has often been associated with these traits and tumor progression; therefore, elimination or subversion of TGF-beta-responsive pathways should be considered as a mechanistic framework for metastatic events. In this report, we have compared growth and extracellular matrix responses to TGF-beta in six metastatic and six primary tumor-derived cell lines in a mouse model of prostate cancer. We have found that tumor cell lines derived from focal pulmonary metastasis secreted relatively greater quantities of total TGF-betas, lost most or all TGF-beta1 growth inhibition, but responded to TGF-beta1 through induction of the type IV collagenase matrix metalloproteinase-9, whereas cell lines derived from tumors which proliferated at the primary site retained the growth inhibition but lacked collagenase activity. Synthesis of another extracellular matrix protein, plasminogen activator inhibitor 1, was stimulated by TGF-beta1 in both primary as well as metastatic tumors. These results suggest that acquisition of differential responses to the TGF-beta family could result in phenotypic traits which facilitate tumor metastasis from certain primary site clones.

Prostate cancer gene therapy: herpes simplex virus thymidine kinase gene transduction followed by ganciclovir in mouse and human prostate cancer models.

Prostate cancer is the most common internal malignancy in men in the United States. Most cancers are diagnosed when they are locally advanced or metastatic and there is no effective treatment. In this study we evaluated the effectiveness of cytotoxic gene therapy in human PC-3 and DU145 prostate cancer cell lines and in a rodent cell line, RM-1, derived from the mouse prostate reconstitution model system. The cell lines were efficiently transduced in vitro by a replicative-defective recombinant adenovirus (ADV) carrying the herpes simplex virus thymidine kinase gene (HSV-tk). A virus titer-dependent sensitivity to ganciclovir (GCV) was observed. To determine a target therapeutic viral dose in vivo, subcutaneous tumors were generated by injection of RM-1 cells in syngeneic male hosts and injected with escalating doses of HSV-tk virus (5 x 10(7) to 1 x 10(9) pfu). The mice received GCV twice daily for 6 days and were sacrificed when tumor volumes exceeded 2.5 cm3 or when they appeared to be in distress. Because the two highest doses were equally as effective, further controlled studies were performed with the lower dose of 5 x 10(8) pfu with ADV/RSV-tk or a control virus containing the beta-galactosidase gene (ADV/RSV-beta-Gal) and treated with GCV or saline (PBS). The mean tumor volume in the treated animals was 16% that of control animals at 13 days. Histologically, treated tumors demonstrated necrosis and had a significantly higher apoptotic index. Survival data indicated that the treatment animals lived 7 days (21 in total) longer than the control animals, with 1 treatment animal being totally free of tumor. These results demonstrate that HSV-tk + GCV cytotoxic gene therapy can inhibit the growth of mouse and human prostate cancer cells in vitro and interrupt tumor growth of an aggressive mouse prostate cancer cell line in vivo.