Mipsagargin, a novel thapsigargin-based PSMA-activated prodrug: results of a first-in-man phase I clinical trial in patients with refractory, advanced or metastatic solid tumours.

BACKGROUND: Mipsagargin (G-202; (8-O-(12-aminododecanoyl)-8-O-debutanoyl thapsigargin)-Asp-γ-Glu-γ-Glu-γ-GluGluOH)) is a novel thapsigargin-based targeted prodrug that is activated by PSMA-mediated cleavage of an inert masking peptide. The active moiety is an inhibitor of the sarcoplasmic/endoplasmic reticulum calcium adenosine triphosphatase (SERCA) pump protein that is necessary for cellular viability. We evaluated the safety of mipsagargin in patients with advanced solid tumours and established a recommended phase II dosing (RP2D) regimen. METHODS: Patients with advanced solid tumours received mipsagargin by intravenous infusion on days 1, 2 and 3 of 28-day cycles and were allowed to continue participation in the absence of disease progression or unacceptable toxicity. The dosing began at 1.2 mg m(-2) and was escalated using a modified Fibonacci schema to determine maximally tolerated dose (MTD) with an expansion cohort at the RP2D. Plasma was analysed for mipsagargin pharmacokinetics and response was assessed using RECIST criteria. RESULTS: A total of 44 patients were treated at doses ranging from 1.2 to 88 mg m(-2), including 28 patients in the dose escalation phase and 16 patients in an expansion cohort. One dose-limiting toxicity (DLT; Grade 3 rash) was observed in the dose escalation portion of the study. At 88 mg m(-2), observations of Grade 2 infusion-related reaction (IRR, 2 patients) and Grade 2 creatinine elevation (1 patient) led to declaration of 66.8 mg m(-2) as the recommended phase II dose (RP2D). Across the study, the most common treatment-related adverse events (AEs) were fatigue, rash, nausea, pyrexia and IRR. Two patients developed treatment-related Grade 3 acute renal failure that was reversible during the treatment-free portion of the cycle. To help ameliorate the IRR and creatinine elevations, a RP2D of 40 mg m(-2) on day 1 and 66.8 mg m(-2) on days 2 and 3 with prophylactic premedications and hydration on each day of infusion was established. Clinical response was not observed, but prolonged disease stabilisation was observed in a subset of patients. CONCLUSIONS: Mipsagargin demonstrated an acceptable tolerability and favourable pharmacokinetic profile in patients with solid tumours.

Relationship of negative emotionality, NIAAA recovery, and 3- and 6-month drinking outcomes among adults in treatment for alcohol use disorder.

BACKGROUND: The National Institute of Alcohol Abuse and Alcoholism (NIAAA) recently released a new definition of recovery from alcohol use disorder (AUD). A patient is considered recovered if they are remitted from DSM-5 AUD and report cessation of heavy drinking. The NIAAA has also recently proposed the Addictions Neuroclinical Assessment (ANA) to guide treatment research. Negative emotionality is one of three domains of the ANA and theory proposes that AUD is maintained by negative reinforcement via the relief of negative affect. The purpose of the current study was to examine: (1) the relationship of end-of-treatment negative emotionality and NIAAA recovery, and (2) the ability of NIAAA recovery at the end of treatment to predict three- and six-month drinking outcomes. METHOD: At baseline and end-of-treatment, women and men (n = 181) in treatment for AUD completed measures of negative emotionality, drinking, and were assessed for DSM-5 AUD diagnostic criteria. At three- and six-months post-treatment, drinking was re-assessed. RESULTS: 22.5% (n = 24) of participants met full criteria for NIAAA recovery at end-of-treatment. Lower levels of end of treatment negative emotionality were associated with increased odds of achieving NIAAA recovery. Meeting NIAAA recovery predicted greater percent days abstinent (PDA) and lower percent heavy drinking days (PHDD) at 3-months, but not at 6-months post-treatment. CONCLUSIONS: This study is among the first to report a relationship between the negative emotionality domain of the ANA and NIAAA recovery. Results underscore the importance of addressing negative emotionality in treatment. Findings also suggest that NIAAA recovery predicts positive short term drinking outcomes.

Sunitinib in combination with docetaxel and prednisone in chemotherapy-naive patients with metastatic, castration-resistant prostate cancer: a phase 1/2 clinical trial.

BACKGROUND: This phase 1/2 study assessed sunitinib combined with docetaxel (Taxotere) and prednisone in chemotherapy-naive metastatic, castration-resistant prostate cancer (mCRPC) patients. PATIENTS AND METHODS: To determine the recommended phase 2 dose (RP2D), 25 patients in four dose escalation cohorts received 3-week cycles of sunitinib (2 weeks on, 1 week off), docetaxel and prednisone, preceded by a 4-week sunitinib 50 mg/day lead in. RP2D was evaluated in 55 additional patients. The primary end point was prostate-specific antigen (PSA) response rate. RESULTS: One phase 1 dose-limiting toxicity occurred (grade 3 hyponatremia). The RP2D was sunitinib 37.5 mg/day, docetaxel 75 mg/m(2) and prednisone 5 mg b.i.d. During phase 2, confirmed PSA responses occurred in 31 patients [56.4% (95% confidence interval 42.3-69.7)]. Median time to PSA progression was 9.8 months. Forty-one patients (75%) were treated >3 months, 12 (22%) completed the study (16 cycles) and 43 (78%) discontinued (36% for disease progression and 27% adverse events). The most frequent treatment-related grade 3/4 adverse events were neutropenia (53%; 15% febrile) and fatigue/asthenia (16%). Among 33 assessable patients, 14 (42.4%) had confirmed partial response. Median progression-free and overall survivals were 12.6 and 21.7 months, respectively. CONCLUSION: This combination was moderately well tolerated, with promising response rate and survival benefit, justifying further investigation in mCRPC.

A phase I study to determine the safety, pharmacokinetics and pharmacodynamics of a dual VEGFR and FGFR inhibitor, brivanib, in patients with advanced or metastatic solid tumors.

BACKGROUND: This study was designed to determine the safety, pharmacokinetics (PK) and pharmacodynamics (PD) of brivanib in patients with advanced/metastatic solid tumors. PATIENTS AND METHODS: Ninety patients enrolled in this two-part, phase I open-label study of oral brivanib alaninate. The primary objectives of this study were (in part A) dose-limiting toxicity, maximum tolerated dose (MTD) and the lowest biologically active dose level and (in part B) the optimal dose/dose range. The secondary objectives of this study were preliminary evidence of antitumor activity, PK and PD. RESULTS: Across part A (open-label dose escalation and MTD) and part B (open-label dose optimization), 68 patients received brivanib alaninate. Brivanib demonstrated a manageable toxicity profile at doses of 180-800 mg. Most toxic effects were mild. Systemic exposure of the active moiety brivanib increased linearly ≤1000 mg/day. The MTD was 800 mg/day. Forty-four patients were treated at the MTD: 20 with 800 mg continuously, 11 with 800 mg intermittently and 13 with 400 mg b.i.d. doses. Partial responses were confirmed in two patients receiving brivanib ≥600 mg. Dynamic contrast-enhanced magnetic resonance imaging demonstrated statistically significant decreases in parameters reflecting tumor vascularity and permeability after multiple doses in the 800-mg continuous q.d. and 400-mg b.i.d. dose cohorts. CONCLUSION: In patients with advanced/metastatic cancer, brivanib demonstrates promising antiangiogenic and antitumor activity and manageable toxicity at doses ≤800 mg orally q.d., the recommended phase II study dose.

Timing of the definitive procedure and ileostomy closure for total colonic aganglionosis HD: Systematic review.

AIM: To establish the cogency of recommendations for the appropriate age for pull-through and ileostomy closure in Total Colonic Aganglionosis-Hirschsprung Disease's (TCA-HD). METHOD: Medline, PubMed, Cochrane, and the ClinicalKey databases were searched without date restriction. The studies that reported TCA-HD cases were evaluated for the number of cases, age at the definitive procedure, age at the ileostomy closure, reported complications, and the type of procedure. Perianal excoriation and diaper rash rates were analyzed using SPSS software, with p < 0.05 considered significant. RESULTS: Twenty-five studies mentioned TCA-HD findings between 1968 and 2019. The total number of patients who had definitive surgery was 218. Analysis showed no correlation between development of diaper rash and the age of the patient at the time of the definitive surgery or ileostomy closure. Studies scored between six and nine of nine possible stars on the NOS scoring system. CONCLUSION: There is no correlation between age of surgery and postoperative diaper rash. Delaying the definitive procedure or ileostomy closure for TCA-HD has limited support on a review of current studies. The perianal excoriation/diaper rash is not reported in the literature at a high enough frequency to warrant keeping a diverting ileostomy until toilet trained of urine. TYPE OF STUDY: Systematic review and meta-analysis. Levels of evidence IV.

A phase I study of an oral simulated FOLFOX with high dose capecitabine.

BACKGROUND: A phase I study of high-dose capecitabine given over 2 days, along with oxaliplatin, bolus 5FU and leucovorin (LV), was designed to simulate FOLFOX6 without the need for infusional 5FU. METHODS: Schedule A included oxaliplatin 100 mg/m(2), 5FU 400 mg/m(2), and LV 20 mg/m(2) (all given IV on days 1 and 15, 28 day cycle). Capecitabine was administered orally every 8 h x 6 doses, days 1 and 15. Schedule B excluded 5FU and LV, maintaining oxaliplatin and capecitabine. Pharmacokinetics were performed for capecitabine for 6 patients on each schedule. RESULTS: 36 patients were treated. The dose-limiting toxicities seen included nausea, dehydration, fatigue, hypotension and confusion. Minimal palmar-plantar erythrodysesthesia was seen. Myelosuppression was common, but not a dose limiting toxicity. The pharmacokinetic parameters for capecitabine were unaltered. CONCLUSION: Using capecitabine to mimic FOLFOX6 is feasible and well tolerated with a toxicity profile that differs from standard 14-day capecitabine dosing, with less palmar-plantar erythrodysesthesia. The phase II dose for capecitabine in combination with oxaliplatin, 5FU, and LV is 1,500 mg/m(2)/dose or 2,250 mg/m(2)/dose in the absence of bolus 5FU/LV.

Reduced warfarin binding of albumin variants.

Binding studies of albumins A/A and A/Me from human plasma and isolated albumin revealed small, but statistically significant, reductions in warfarin binding of albumin A/Me compared to albumin A/A. Such differences in binding in vitro could result in altered pharmacological responses to warfarin administered to individuals possessing albumin A/Me. To determine if clinically significant differences in warfarin distribution exist, observations should be made in vivo on patients of different albumin phenotype who are receiving warfarin therapeutically.

Biologic features and treatment outcome of secondary acute lymphoblastic leukemia--a review of 101 cases.

BACKGROUND: Secondary acute lymphoblastic leukemia (sALL) is a rare disease and its biologic features are not well characterized. PATIENTS AND METHODS: We describe a cohort of seven patients and discuss 94 additional cases from the literature for whom biological parameters were described. Cases with incomplete data were excluded. RESULTS: Hodgkin's disease (HD) was more common in the 18-59 age group while breast and prostate cancers were prevalent only in the >or=18-year-old patients. The time interval to develop sALL was similar among all age groups but was significantly longer for HD and neuroblastoma primary diagnoses and sALL with complex karyotype. T-cell immunophenotype was more common in the <18 age group. Complete remission was infrequent in the >or=60 age group. The overall survival was poor for all sALL regardless of age, primary diagnoses, cytogenetic subgroups, or immunophenotype. Allogeneic transplantation most probably represents the only chance of cure. CONCLUSION: Better identification of prognostic factors to prevent the occurrence of sALL is indicated.

Osteoporosis and oral infection: independent risk factors for oral bone loss.

Studies have suggested that oral bone loss is independently influenced by local and systemic factors, including osteoporosis. This cross-sectional study of 1256 post-menopausal women, recruited from the Buffalo center of the Women's Health Initiative Observational Study, evaluated the influence of oral infection and age on the associations between osteoporosis and oral bone loss. Systemic bone density was measured by dual-energy x-ray absorptiometry. Alveolar crestal height was measured from standardized dental radiographs. Oral infection was assessed from subgingival plaque samples. Total forearm density [beta (SE)= -0.931 (0.447), p=0.038] and presence of Tannerella forsythensis [beta (SE)=0.125 (0.051), p=0.015] were independently associated with mean alveolar height among women aged <70 years after confounder adjustment. Women aged 70+ years had worse oral bone loss, in general, but neither bone density nor oral infection was significantly associated with mean alveolar height in this age group. Systemic bone density and oral infection independently influenced oral bone loss in post-menopausal women aged <70 years.

Small bowel fed response as measured by wireless motility capsule: Comparative analysis in healthy, gastroparetic, and constipated subjects.

BACKGROUND: Small bowel fed response is an increased contractile activity pattern following the ingestion of a meal. Postprandial motility is traditionally evaluated using small bowel manometry. Wireless motility capsule (WMC) is an ingestible wireless capsule that measures pH, temperature, and intraluminal pressure. The primary aim of the study was to assess small bowel fed response captured with the non-invasive WMC. The secondary aim was to compare the fed response patterns between healthy subjects and patients with motility disorders of gastroparesis and constipation. METHODS: All subjects had 250 cc Ensure® meal 6 hours after WMC ingestion. Frequency of contractions (Ct), area under the curve (AUC), and motility index (MI) were analyzed during 30 minutes of pre-prandial baseline and 60 minutes postprandially in 20-minute windows. KEY RESULTS: One hundred and eighty-eight subjects (107 healthy, 23 gastroparetics, 58 constipated) were analyzed. Healthy: Ct, AUC, and MI all increased significantly immediately after meal ingestion (P < .01). Motility parameters peak at 20-40 minutes postmeal. The motor activity decreased at the end of postprandial hour, but was still significantly higher than the fasting baseline (P < .01). Gastroparetics: All motility parameters failed to increase significantly compared to the baseline throughout the entire postprandial hour. Constipated: The fed response was similar to healthy subjects. CONCLUSIONS AND INFERENCES: The small bowel fed response was readily observed in healthy and chronic constipation subjects with WMC but is blunted in gastroparetics. A blunted small bowel fed response suggests neuropathic changes outside the stomach and may contribute to postprandial symptoms.

Prooxidant-antioxidant shift induced by androgen treatment of human prostate carcinoma cells.

BACKGROUND: Prostate cancer is a disease associated with aging. Also commonly associated with increasing age is a shift in the prooxidant-antioxidant balance of many tissues toward a more oxidative state, i.e., increased oxidative stress. We hypothesize that androgen exposure, which has long been associated with the development of prostate cancer, may be a means by which the prooxidant-antioxidant balance of prostate cells is altered. PURPOSE: Using established prostate carcinoma cell lines, we studied the effect of androgens on various parameters of oxidative state (e.g., generation of hydrogen peroxide and hydroxyl radicals, lipid peroxidation, and oxygen consumption) and antioxidant defense mechanisms (e.g., the glutathione system and catalase). METHODS: The androgen-responsive LNCaP and the androgen-independent DU145 prostate carcinoma cell lines were exposed to 5 alpha-dihydrotestosterone (DHT) and to the synthetic androgen R1881. The cellular proliferation responses were measured by use of a fluorometric assay to quantitate the amount of DNA. The generation of reactive oxygen species was measured by use of 2',7'-dichlorofluorescin diacetate, a dye that fluoresces in the presence of hydrogen peroxide or hydroxyl radicals. Lipid peroxidation was quantitated by use of a chromogen specific for malonaldehyde and 4-hydroxy-2(E)-nonenal. General mitochondrial activity was determined by assaying 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction. A Clark-type electrode was used to assess oxygen consumption per cell. Intracellular glutathione concentrations and the activities of catalase and gamma-glutamyl transpeptidase were measured spectrophotometrically. All P values resulted from two-sided tests. RESULTS: DHT at less than 1 to 100 nM (a concentration range encompassing the physiologic levels of DHT considering all ages) and R1881 at 0.1-1 nM concentrations were effective in inducing in LNCaP cells comparable proliferative responses and changes in oxidative stress. In contrast, neither DHT nor R1881 had any effect on the oxidative stress in DU145 cells. The mitochondrial activity in LNCaP cells, as measured by MTT reduction, was significantly elevated above the levels of the untreated controls by DHT (0.1-1000 nM) and R1881 (0.05-1 nM) (P < .001 in both). Oxygen consumption and catalase activity were increased in LNCaP cells in the presence of 1 nM R1881 by 60% and 40%, respectively, over the values in the untreated control cells (P < .03 and P < .01, respectively). The same concentration of R1881 resulted in a decrease in intracellular glutathione concentrations and an increase in gamma-glutamyl transpeptidase activity in LNCaP cells. Treatment with the oxidizing agents H2O2 and menadione produced an increase in gamma-glutamyl transpeptidase activity in LNCaP cells, whereas treatment with the antioxidant compound ascorbic acid (100 mM) reduced the oxidative stress produced in LNCaP cells by 1 nM R1881 and completely blocked the gamma-glutamyl transpeptidase activity. CONCLUSIONS: Physiologic levels of androgens are capable of increasing oxidative stress in androgen-responsive LNCaP prostate carcinoma cells. The evidence suggests that this result is due in part to increased mitochondrial activity. Androgens also alter intracellular glutathione levels and the activity of certain detoxification enzymes, such as gamma-glutamyl transpeptidase, that are important for maintenance of the cellular prooxidant-antioxidant balance.

Effect of antioxidants on androgen-induced AP-1 and NF-kappaB DNA-binding activity in prostate carcinoma cells.

BACKGROUND: Previous studies have suggested that male hormones (androgens) and certain forms of oxygen (reactive oxygen species) are linked to the development of prostate cancer. We hypothesized that androgens contribute to prostate carcinogenesis by increasing oxidative stress. We further hypothesized that antioxidants reduce prostate cancer risk by modulating androgen effects on cellular processes. METHODS: To test these hypotheses, we looked for 1) a change in the level of reactive oxygen species in the presence of androgens, 2) androgen-induced binding activity of transcriptional activators AP-1 and NF-kappaB, whose activities are known to be altered during cell proliferation, and 3) the effect of antioxidants on androgen-induced transcription factor binding. RESULTS: Physiologic concentrations (1 nM) of 5alpha-dihydrotestosterone or 1-10 nM R1881, a synthetic androgen, produced sustained elevation of AP-1 and NF-kappaB DNA-binding activity in LNCaP cells, an androgen-responsive human prostate carcinoma cell line. Androgen-independent DU145 cells (another human prostate carcinoma cell line) were unaffected by R1881 treatment. AP-1-binding activity increased 5 hours after 1 nM R1881 treatment; NF-kappaB DNA-binding activity increased after 36 hours. Both activities remained elevated for at least 120 hours. Nuclear AP-1 and NF-kappaB protein levels were not elevated. Antioxidant vitamins C plus E blocked both androgen-induced DNA-binding activity and production of reactive oxygen species. CONCLUSION: Physiologic concentrations of androgens induce production of reactive oxygen species and cause prolonged AP-1 and NF-kappaB DNA-binding activities, which are diminished by vitamins C and E.

Randomized phase I chemoprevention dose-seeking study of alpha-difluoromethylornithine.

BACKGROUND: alpha-Difluoromethylornithine (DFMO) is an irreversible inhibitor of ornithine decarboxylase (ODC), the key enzyme in mammalian polyamine biosynthesis. Levels of ODC are closely related to tumor promotion, and inhibition of ODC is associated with suppression of tumor development in laboratory animals. DFMO has shown a dose-response effect in tumor inhibition in mice. PURPOSE: A randomized phase I study of DFMO was conducted to determine the lowest daily oral dose that can achieve at least 50% inhibition of ODC activity induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in human skin, with minimal clinical toxicity (grade 1 or lower; Eastern Cooperative Oncology Group [ECOG]). METHODS: Cancer patients entered in steps 1 and 2 of the study had been treated and had no clinical evidence of cancer. In step 1, 13 patients received 0.125, 0.25, 0.5, or 0.75 g/m2 DFMO four times a day. In step 2, 13 patients received 0.125 or 0.25 g/m2 four times a day or 0.5 or 1.0 g/m2 every day. The 26 patients treated in steps 1 and 2 (range, < 1-6 months) had colon, prostate, or bladder cancer. In step 3, six cancer-free subjects at risk for colorectal cancer received 0.5 g/m2 every day for 5-12 months. To evaluate the effectiveness of DFMO in reducing TPA-induced ODC activity, we calculated the percent change from pretreatment ODC levels in skin biopsy specimens and the percentage of subjects with at least a 50% reduction in ODC levels. RESULTS: In step 1 of the study, treatment-limiting audiotoxicity was observed at the three highest doses. Because the only dose with no major toxic effects in step 2 was 0.5 g/m2 every day, that dose was administered in step 3, with no major toxic effects. Seven subjects treated with 0.5 g/m2 every day had pretreatment ODC levels in the normal range; five averaged a reduction in ODC activity of at least 50%. DFMO had linear pharmacokinetics over the entire dose range. When 0.5 g/m2 was given every day, the peak plasma concentration was 47.1 +/- 5.1 microM at 3-4 hours (monthly mean +/- SE, 14.5 +/- 5.2 microM); half-life was 3.5 hours; and area under the curve for plasma concentration x time for a single dose of DFMO was 311 +/- 39 microM x hour. CONCLUSIONS: These data support phase II chemoprevention studies with DFMO given at a dose of 0.5 g/m2 every day. IMPLICATIONS: Studies investigating prevention of cancers with DFMO are under consideration.

Phase I study of continuous-infusion L-S,R-buthionine sulfoximine with intravenous melphalan.

BACKGROUND: Increased intracellular glutathione has long been associated with tumor cell resistance to various cytotoxic agents. An inhibitor of glutathione biosynthesis, L-S,R-buthionine sulfoximine (BSO), has been shown to enhance the cytotoxicity of chemotherapeutic agents in vitro and in vivo. We performed a phase I study of BSO administered with the anticancer drug melphalan to determine the combination's safety/tolerability and to determine clinically whether BSO produced the desired biochemical end point of glutathione depletion (<10% of pretreatment value). METHODS: Twenty-one patients with advanced cancers received an initial 30-minute infusion of BSO totaling 3.0 g/m2 and immediately received a continuous infusion of BSO on one of the following schedules: 1) 0.75 g/m2 per hour for 24 hours (four patients); 2) the same dose rate for 48 hours (four patients); 3) the same dose rate for 72 hours (10 patients); or 4) 1.5 g/m2 per hour for 48 hours (three patients). During week 1, the patients received BSO alone; during weeks 2 or 3, they received BSO plus melphalan (15 mg/m2); thereafter, the patients received BSO plus melphalan every 4 weeks. Glutathione concentrations in peripheral blood lymphocytes were determined for all patients; in 10 patients on three of the administration schedules, these measurements were made in multiple sections from tumor biopsy specimens taken before, during, and after continuous-infusion BSO. RESULTS: Continuous-infusion BSO alone produced minimal toxic effects, although BSO plus melphalan produced occasional severe myelosuppression (grade 4) and frequent low-grade nausea/vomiting (grade 1-2). This treatment also produced consistent, profound glutathione depletion (<10% of pretreatment value). The degree of glutathione depletion in peripheral lymphocytes was considerably less than that observed in tumor sections. CONCLUSIONS: Continuous-infusion BSO is relatively nontoxic and results in depletion of tumor glutathione.

Alteration of glyceraldehyde-3-phosphate dehydrogenase activity and messenger RNA content by androgen in human prostate carcinoma cells.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12) activity and mRNA content is altered in the androgen-responsive human prostate carcinoma cell line LNCaP after exposure to the synthetic androgen R1881. Elevation in GAPDH activity is noted as early as 24 h after treatment with 1 nM R1881 and lasts at least 96 h. R1881 has no effect on the activity of GAPDH in androgen-independent DU145 cells. LNCaP GAPDH mRNA content is lowered by treatment with 1 nM R1881; the magnitude of reduction appears to depend on the length of exposure. The results present at least one means by which androgen-responsive tissues may develop alterations in GAPDH mRNA or activity, as is found in certain tumor tissues.

Effects of steroid hormones and peptide growth factors on protooncogene c-fos expression in human breast cancer cells.

To investigate if the estrogen control of the tumorigenic phenotype of breast cancer cells was mediated through activation of the c-fos protooncogene, we examined the expression of this oncogene in MCF-7 cells. In cells synchronized by double thymidine blockade, the peptide growth factors transforming growth factor alpha and epidermal growth factor increased c-fos mRNA levels 6-fold above controls after 30 min of treatment. The phorbol ester, 12-O-tetradecanoylphorbol-13-acetate, increased c-fos mRNA levels 4- to 5-fold above control. 17 beta-Estradiol, a growth stimulator, increased c-fos mRNA levels less than 2-fold above control levels, while progesterone, vitamin D3, dihydrotestosterone, and dexamethasone had little effect on c-fos mRNA levels. In contrast, 17 beta-estradiol treatment initially diminished the c-myc RNA level after 30 min of treatment and resulted in an elevation of c-myc by 2.5 h after initiation of treatment. We conclude that c-fos induction in these cells is growth related and accompanies stimulation by transforming growth factor alpha and epidermal growth factor. 17 beta-Estradiol, on the other hand, induced much smaller increases in c-fos mRNA levels, suggesting an alternative or more complex mechanism of cellular stimulation.

Disruption of mitochondrial function by suramin measured by rhodamine 123 retention and oxygen consumption in intact DU145 prostate carcinoma cells.

Suramin, an antiparasitic drug, has shown antitumor activity in humans. This may occur in part through disruption of energy balance, which is believed to be part of its antiparasitic action. Suramin disrupts mitochondrial function in intact DU145 prostate carcinoma cell monolayers as seen by its causing the release of rhodamine 123 from prestained cells beginning at about 10 microM in 96-well microtiter plates measured with a fluorescent plate scanner. This effect was similar to the ionophore carbonyl cyanide m-chlorophenylhydrazone, dissolved in ethanol at 0.01 N and indicates that suramin acts as a respiratory poison or an ionophore. This effect was confirmed by studies of oxygen consumption with a Clark oxygen electrode and cellular ATP content which demonstrated uncoupling of oxidative phosphorylation by 100 microM suramin, a clinically achievable plasma drug level.

Alteration in gamma-glutamyl transpeptidase activity and messenger RNA of human prostate carcinoma cells by androgen.

Concentrations of the synthetic androgen R1881 that correspond to physiologically relevant concentrations of 5alpha-dihydrotestosterone are capable of altering the activity of gamma-glutamyl transpeptidase (GGT) in human prostate carcinoma cells. GGT activity of the androgen-responsive prostate cancer cell line LNCaP increases >50% above that of the control after a 72-h exposure to 1 nM R1881. This elevation in GGT activity occurs as early as 48 h after treatment and is maintained for at least 96 h. Loss of glutathione (GSH) from media and accumulation of intracellular GSH of cells pretreated with 1 nM R1881 occur at a higher rate than in control cells, suggesting that a greater rate of GSH salvage is associated with the increased GGT activity. Immunohistochemical staining detects an increase in GGT-positive staining in cells treated with 1 nM R1881 for 72 h. Steady-state mRNA levels for GGT are elevated above those of the control 24-72 h after treatment. R1881 has no effect on the GGT activity of the androgen-independent prostate cell line DU145. Growth of LNCaP but not DU145 cells is inhibited by 1 nM R1881 compared to that of the control. Inhibitors of GGT activity, acivicin and serine-borate, are capable of dampening or blocking the effect of R1881 on growth. Growth of LNCaP cells treated with 1 nM R1881 plus 100 mM glycylglycine, a stimulator of GGT activity, is inhibited to a greater extent than the growth of LNCaP cells treated with R1881 alone. These data demonstrate that androgens can elevate GGT activity and increase GGT mRNA and protein levels in human prostate carcinoma cells. In addition, compounds able to alter GGT activity are capable of altering androgen-related growth effects.

Disruption of cellular energy balance by suramin in intact human prostatic carcinoma cells, a likely antiproliferative mechanism.

The antiparasitic drug, suramin, has antiproliferative effects in human carcinoma cells. It has been suggested that this occurs through blockade of growth factor-receptor interactions. Three types of evidence that suramin rapidly inhibits cellular respiration or disrupts cellular energy balance in intact cells of the human prostate carcinoma cell line, DU145, are presented. Beginning at approximately 10(-4) M, suramin rapidly causes dose-dependent inhibition of tetrazolium conversion by mitochondrial dehydrogenases in intact cells, demonstrating an inhibition of respiration. This effect is reversed by exchange with suramin-free media but not by pretreatment with serum, epidermal growth factor, insulin-like growth factor I, acidic and basic fibroblast growth factors, or calcium. Rhodamine 123 (10 micrograms/ml) uptake by mitochondria in intact DU145 cells is inhibited in the presence of 10(-3) M suramin. Treatment with 10(-4)-10(-3) M suramin causes the loss of rhodamine 123 from cells with mitochondria prestained with rhodamine 123, indicating that suramin is acting as an ionophore or respiratory poison. Also shown by electron microscopy are progressive toxic changes in mitochondria of DU145 cells within 1 h after treatment with 10(-4) M suramin. These data indicate that in intact DU145 cells 10(-4) M suramin rapidly disrupts cellular energy balance or respiration as seen by three studies of mitochondrial state. Disruption of energy balance or respiration represents a likely antiproliferative mechanism, as is thought to be a primary mechanism for the action of suramin in parasitic diseases. This proposed mechanism of action for suramin can explain the most prominent observed clinical toxicities of nephrotoxicity, adrenal toxicity, coagulopathy, and demyelinating neuropathy.