Gerald Batist

Use of Statins and the Risk of Death in Patients With Prostate Cancer

PURPOSE To determine whether the use of statins after prostate cancer diagnosis is associated with a decreased risk of cancer-related mortality and all-cause mortality and to assess whether this association is modified by prediagnostic use of statins. PATIENTS AND METHODS A cohort of 11,772 men newly diagnosed with nonmetastatic prostate cancer between April 1, 1998, and December 31, 2009, followed until October 1, 2012, was identified using a large population-based electronic database from the United Kingdom. Time-dependent Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs) with 95% CIs of mortality outcomes associated with postdiagnostic use of statins, lagged by 1 year to account for latency considerations and to minimize reverse causality, and considering effect modification by prediagnostic use of statins. RESULTS During a mean follow-up time of 4.4 years (standard deviation, 2.9 years), 3,499 deaths occurred, including 1,791 from prostate cancer. Postdiagnostic use of statins was associated with a decreased risk of prostate cancer mortality (HR, 0.76; 95% CI, 0.66 to 0.88) and all-cause mortality (HR, 0.86; 95% CI, 0.78 to 0.95). These decreased risks of prostate cancer mortality and all-cause mortality were more pronounced in patients who also used statins before diagnosis (HR, 0.55; 95% CI, 0.41 to 0.74; and HR, 0.66; 95% CI, 0.53 to 0.81, respectively), with weaker effects in patients who initiated the treatment only after diagnosis (HR, 0.82; 95% CI, 0.71 to 0.96; and HR, 0.91; 95% CI, 0.82 to 1.01, respectively). CONCLUSION Overall, the use of statins after diagnosis was associated with a decreased risk in prostate cancer mortality. However, this effect was stronger in patients who also used statins before diagnosis.

Connexin43 pseudogene is expressed in tumor cells and inhibits growth.

Pseudogenes are classically thought of as nonfunctional DNA sequences due to their inability to be translated, or to produce a functional protein. Gap junctions, a multiprotein complex made of proteins called connexins, are involved in intercellular communication and are deregulated in many cancers. Connexin43 (Cx43) is the only connexin for which a pseudogene has been reported so far. The Cx43 pseudogene (ΨCx43) has all of the features of an expressed gene. We identified the presence of a ΨCx43 mRNA transcript in several cancer cell lines and in none of the normal mammary epithelial cells studied. Using an in vitro translation assay, we found that the ΨCx43 coding plasmid could be translated into a 43 kDa protein. This was further confirmed by expressing a ΨCx43-green fluorescence protein fusion protein in breast cancer MCF-7 cells. We then examined the functional significance of the ΨCx43. In both MTT growth and colony formation assays, significant growth inhibition was observed, a feature common to cells overexpressing the Cx43 gene. However, using a scrape-loading assay, we could not detect any effect on gap junctional intercellular communication. Based on our findings, ΨCx43 joins and enlarges the thus far restricted group of functionally transcribed and translated pseudogenes.

Cul3 overexpression depletes Nrf2 in breast cancer and is associated with sensitivity to carcinogens, to oxidative stress, and to chemotherapy

Nrf2 is the key transcription factor for cytoprotective gene programs. Nrf2 is normally maintained at very low concentrations by proteasomal degradation, through its interaction with the adapter protein Keap1 and the Cul3 E3 ligase. Increased Nrf2 concentration resulting from loss of function Keap1 mutations has been described in chemoresistant non–small cell lung cancer. Previous studies in breast cancer showed low levels of some Nrf2-regulated detoxification genes, but the mechanism has not been systematically examined. We found that half of the breast cancer cell lines examined have decreased concentration of Nrf2 compared with normal mammary epithelial cell lines, associated with variable but detectable levels in Keap1 levels, and consistently increased Cul3 mRNA and protein. Immunochemistry showed that 7 of 10 breast cancer specimens examined also have low Nrf2 levels and increased Cul3. Keap1 protein levels are variable. We found no C23Y mutation in Keap1 of any of the cell lines. Using siRNA, we silenced Cul3 in MCF-7 breast cancer cells, and microarray analysis reveals the induction of GCL, NQO1, AKR1C1, UGDH, and TXN by at least 2-fold. The Nrf2-regulated ABCC1 drug transporter was also found to be increased. These Cul3-silenced MCF7 cells are highly resistant to oxidative stress induced by H2O2, to the carcinogen benzo(a)pyrene, and to both Doxorubicin and Paclitaxel. This high Cul3/low Nrf2 signature may be key to cellular sensitivity to both chemical carcinogeneic stimuli as well as to cytotoxicity of commonly used chemotherapeutic drugs in established breast cancers. [Mol Cancer Ther 2009;8(8):2432–40]

Overexpression of cytochrome P-450 isoforms involved in aflatoxin B1 bioactivation in human liver with cirrhosis and hepatitis.

Studies were carried out to test the hypothesis that inflammatory liver disease increases the expression of specific cytochrome P-450 isoenzymes involved in aflatoxin B1 (AFB) activation. The immunohistochemical expression and localization of various human cytochrome P-450 isoforms, including CYP2A6, CYP1A2, CYP3A4, and CYP2B1, were examined in normal human liver and liver with hepatitis and cirrhosis. The constitutive expression of CYP3A4 in normal liver showed a characteristic pattern of distribution in centrilobular hepatocytes, whereas CYP1A2, CYP2A6, and CYP2B1 1 were expressed uniformly throughout the liver acinus. In sections of liver infected with hepatitis B virus (HBV) or hepatitis C virus (HCV), the expression of CYP2A6 was markedly increased in hepatocytes immediately adjacent to areas of fibrosis and inflammation. CYP3A4 and CYP2B 1 were induced to a lesser degree, and expression of CYP1A2 was unaffected. In HBV-infected liver, double immunostaining revealed that overexpression of CYP2A6 occurred in hepatocytes expressing the HBV core antigen. In HCV-infected liver, CYP2A6, CYP3A4, and CYP2B 1 were overexpressed in hepatocytes with hemosiderin pigmentation. These results suggest that alterations in phenotypic expression of specific P-450 isoenzymes in hepatocytes associated with hepatic inflammation and cirrhosis might increase susceptibility to AFB genotoxicity.

Etoposide (VP-16) and cisplatin in previously treated small-cell lung cancer: clinical trial and in vitro correlates.

Treatment of patients with relapsed small-cell lung cancer (SCLC) has been uniformly unsuccessful. Recently, the combination of etoposide (VP-16) and cisplatin in this setting has been reported to result in up to 50% response rates. We treated 29 patients with relapsed SCLC with this combination and found only a 12% response rate. The discrepancy between our results and those of others is most likely due to differences in prior treatment of the patients, although the effect of dose and schedule modifications are considered. Our patients had received a six-drug regimen over a median of 7 months and had a median drug-free interval before this treatment of only 3 weeks. Evidence is presented that suggests that this aggressive initial therapy affected both host tolerance to further treatment and the development of tumor resistance at the cellular level.

Sensitization to doxorubicin resistance in breast cancer cell lines by tamoxifen and megestrol acetate

Acquired drug resistance is a major factor in the failure of doxorubicin-based chemotherapy in breast cancer. We determined the ability of megestrol acetate and/or tamoxifen to reverse doxorubicin drug resistance in a doxorubicin-resistant breast cancer line (the human MCF-7/ADR). The cytotoxicity of doxorubicin, megestrol acetate, and/or tamoxifen was determined in the sensitive and resistant cell lines utilizing the sulphorhodamine B assay. Tamoxifen alone produced an IC50 (concentration resulting in 50% inhibition of control growth) of 10.6 microM, whereas megestrol acetate alone resulted in an IC50 of 48.7 microM in the MCF-7/ADR cell line. The IC50 of doxorubicin in MCF-7/ADR was 1.9 microM. Neither megestrol acetate alone nor tamoxifen alone at 1 or 5 microM altered the IC50 of doxorubicin. However, the combination of tamoxifen (1 or 5 microM) and megestrol acetate (1 or 5 microM) synergistically sensitized MCF-7/ADR cells. Additionally, megestrol acetate and tamoxifen inhibited iodoarylazidoprazosin binding to P-glycoprotein, and, in their presence, there was an increased doxorubicin accumulation in the MCF-7/ADR cells. Furthermore, the combination of tamoxifen and megestrol acetate had much less effect on the cytotoxicity of doxorubicin in MCF-7 wild-type cells. Clinically achievable concentrations of tamoxifen and megestrol acetate can largely sensitize MCF-7/ADR to doxorubicin. The combination of these three drugs in a clinical trial may be informative.

Structure-Based Identification of Novel Human γ-Glutamylcysteine Synthetase Inhibitors

Glutathione depletion represents a potentially important strategy to sensitize tumors to cytotoxic drugs. l-Buthionine-(R,S)-sulfoximine (l-BSO) has been studied in both preclinical and early clinical trials, but limitation on its access has led to a search for alternatives. Using a 3D molecular model of human γ-glutamylcysteine synthetase (γ-GCSH), the major subunit of the rate-limiting GSH synthetic enzyme, we virtually screened the National Cancer Institute chemical database to identify compounds that could bind to and potentially inhibit γ-GCSH. We identified 51 test chemicals, all with structures very distinct from l-BSO. We subjected these compounds to biological assays measuring γ-GCSH inhibition and glutathione (GSH) depletion. Among 10 novel γ -GCS inhibitors identified, 4 compounds depleted glutathione in cells, and 2 with related structures sensitized tumor cells to melphalan treatment. This work validates the use of model-based database mining and identified inhibitors of γ-GCSH with novel chemical structures.

Phase I and pharmacokinetic study of tiazofurin (TCAR, NSC 286193) administered by continuous infusion

SummaryTiazofurin (2-β-D-ribofuranosylthiazole-4-carboxamide, TCAR) is a synthetic C-nucleoside that demonstrated significant in vivo activity against a variety of animal tumors as well as in vitro activity against human tumor-derived cell lines. Thirteen patients were treated with TCAR administered as a 5-day continuous infusion in this Phase I trial. Seventeen complete cycles were administered in three dose levels ranging from 550 to 1450 mg/M2. Dose-limiting toxicities were myelosuppression and neurotoxicity including severe lethargy. Other toxicities including superficial skin peeling, myalgias, and tearing were seen at all doses. One patient had chest pain on day 4 resulting in stopping the drug, however, there was no evidence of cardiac or pericardial disease. Uric acid levels rose within one day in the absence of allopurinol treatment. There were no treatment related deaths. HPLC measurement of drug levels demonstrated steady-state plasma levels during the infusion, and a half-life following the infusion of 7.7 ± 0.6 hours. Minor abnormalities in renal function were associated with dramatic changes in pharmacokinetics and toxicity. No clinical responses were observed in this trial.

Immuno-Matrix-Assisted Laser Desorption/Ionization Assays for Quantifying AKT1 and AKT2 in Breast and Colorectal Cancer Cell Lines and Tumors

The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) pathway is one of the most commonly dysregulated signaling pathways that is linked to cancer development and progression, and its quantitative protein analysis holds the promise to facilitate patient stratification for targeted therapies. Whereas immunohistochemistry (IHC) and immunoassays are routinely used for clinical analysis of signaling pathways, mass spectrometry-based approaches such as liquid chromatography/electrospray ionization multiple reaction monitoring mass spectrometry (LC/ESI-MRM-MS) are more commonly used in clinical research. Both technologies have certain disadvantages, namely, the nonspecificity of IHC and immunoassays, and potentially long analysis times per sample of LC/ESI-MRM-MS. To create a robust, fast, and sensitive protein quantification tool, we developed immuno-matrix-assisted laser desorption/ionization (iMALDI) assays with automated liquid handling. The assays are able to quantify AKT1 and AKT2 from breast cancer and colon cancer cell lines and flash-frozen tumor lysates with a linear range of 0.05-2.0 fmol/μg of total lysate protein and with coefficients of variation < 15%. Compared to other mass spectrometric methods, the developed assays require less sample per analysis-only 25 μg of total protein-and are therefore suitable for analysis of needle biopsies. Furthermore, the presented iMALDI technique is the first MS-based method for absolute quantitation of AKT peptides from cancer tissues. This study demonstrates the suitability of iMALDI for low limit-of-detection and reproducible quantitation of signaling pathway members using a benchtop MALDI mass spectrometer within approximately 6-7 h.

Phase I and pharmacokinetic study of Bay 38-3441, a camptothecin glycoconjugate, administered as a 30-minute infusion daily for five days every 3 weeks in patients with advanced solid malignancies

Bay 38-3441 is a camptothecin glycoconjugate which stabilizes the active lactone form of camptothecin and allows selective uptake into tumor cells. We conducted a phase I study of Bay 38-3441 administered as a 30-minute infusion daily for five consecutive days every 21 days. Thirty-one patients were enrolled at 8 dose levels. Most common nonhematologic side effects were diarrhea (29%), vomiting (19%), nausea (19%), lethargy (13%), and abdominal pain (10%). The main hematologic toxicity was prolonged neutropenia. Nine patients had a best response of stable disease with a median duration of 2.7 months (range: 2.3–20.6 months). The study was closed without reaching the maximum tolerated dose (MTD) due to excessive toxicity in a companion trial resulting in termination of development of this agent. Bay 38-3441 was well tolerated in this study with granulocytopenia as the main hematologic toxicity. This study showed that glycoconjugation is a feasible delivery technique for camptothecin.