Antidepressants in the general hospital.

An approach to the use of antidepressant medication in the general hospital is presented. The type of depression most likely to respond to chemotherapy is described, categories of available antidepressant agents are discussed, and relevant pharmacologic aspects are outlined. This paper suggests clinical guidelines for the use of these drugs, particularly in medical and surgical patients.     

A novel role of DNA polymerase eta in modulating cellular sensitivity to chemotherapeutic agents

Genetic defects in polymerase eta (pol eta; hRad30a gene) result in xeroderma pigmentosum variant syndrome (XP-V), and XP-V patients are sensitive to sunlight and highly prone to cancer development. Here, we show that pol eta plays a significant role in modulating cellular sensitivity to DNA-targeting anticancer agents. When compared with normal human fibroblast cells, pol eta-deficient cells derived from XP-V patients were 3-fold more sensitive to beta-d-arabinofuranosylcytosine, gemcitabine, or cis-diamminedichloroplatinum (cisplatin) single-agent treatments and at least 10-fold more sensitive to the gemcitabine/cisplatin combination treatment, a commonly used clinical regimen for treating a wide spectrum of cancers. Cellular and biochemical analyses strongly suggested that the higher sensitivity of XP-V cells to these agents was due to the inability of pol eta-deficient cells to help resume the DNA replication process paused by the gemcitabine/cisplatin-introduced DNA lesions. These results indicated that pol eta can play an important role in determining the cellular sensitivity to therapeutic agents. The findings not only illuminate pol eta as a potential pharmacologic target for developing new anticancer agents but also provide new directions for improving future chemotherapy regimen design considering the use of nucleoside analogues and cisplatin derivatives.     

Successful adoptive immunotherapy with vaccine-sensitized T cells,despite no effect with vaccination alone in a weakly immunogenic tumor model

Tumor cell vaccines have been successful at inducing immunity in naïve mice, but only in a few reports has vaccination alone induced regression of established tumors and, generally, only when they are very small. Clinically, vaccinations alone may not be able to cause regression of established human cancers, which tend to be weakly immunogenic. We hypothesized that pharmacologic ex vivo amplification of a vaccination-induced immune response with subsequent adoptive immunotherapy (AIT) to tumor-bearing animals would be more effective in treatment of these animals than vaccination alone. The 4T1 and 4T07 mammary carcinomas are derived from the same parental cell line, but 4T1 is much less immunogenic and more aggressive than 4T07. Vaccination with either 4T1, 4T1-IL-2, or 4T07-IL-2 was not effective as treatment for established 4T1 tumors. However, 4T1 or 4T07-IL-2-vaccine-sensitized draining lymph node (DLN) cells, activated ex vivo with bryostatin 1 and ionomycin and expanded in culture, induced complete tumor regressions when adoptively transferred to 4T1 tumor-bearing animals. This was effective against small tumors as well as more advanced tumors, 10 days after tumor cell inoculation. Furthermore, as would be required for this approach to be used clinically, vaccine-DLN cells obtained from mice with established progressive 4T1 tumors (inoculated 10 days before vaccination) also induced regression of 4T1 tumors in an adoptive host. In none of these experiments was exogenous IL-2 required to induce tumor regression. The response to tumor cell vaccine can be amplified by ex vivo pharmacologic activation of sensitized T cells, which can then cure an established, weakly immunogenic and highly aggressive tumor that was resistant to vaccination alone.     

Protection of all cleavable sites of DNA with the multiple CGCG or continuous CGG sites from the restriction enzyme,indicative of simultaneous binding of small ligands

The anthracenone ligands (1–12) with a keto-phenol and a hydroxamic acid unit were synthesized and evaluated by a restriction enzyme inhibition assay. DNA substrates composed of multiple CGCG or CGG sites are fully hydrolyzed by a restriction enzyme that is selective for each sequence. Under such conditions, the full-length DNA substrate remains only when the ligand binds to all binding sites and protects it from hydrolysis by the restriction enzymes. In the assay using AccII and the 50-mer DNA substrates containing a different number of CGCG sites at different non-binding AT base pair intervals, the more the CGCG sites, the more the full-length DNA increased. Namely, simultaneous binding of the ligand (5) to the CGCG sites increased in the order of (CGCG)₅>(CGCG)₂>(CGCG)₁. Furthermore, the length of the spacer of the hydroxamic acid to the anthracenone skeleton played an important role in the preference for the number of the d(A/T) base pairs between the CGCG sites. The long spacer-ligand (5) showed a preference to the CGCG sites with five AT pairs, and the short spacer-ligand (10) to that with two AT pairs. The ligand (12) with the shortest spacer showed a preference in simultaneous binding to the 54-mer DNA composed of 16 continuous CGG sites in the assay using the restriction enzyme Fnu4HI that hydrolyzes the d(GCGGC)/d(CGCCG) site. Application of these ligands to biological systems including the repeat DNA sequence should be of significant interest.     

Efficient nonviral transfection of dendritic cells and their use for in vivo immunization

Immunization with dendritic cells (DCs) transfected with genes encoding tumor-associated antigens (TAAs) is a highly promising approach to cancer immunotherapy. We have developed a system, using complexes of plasmid DNA expression constructs with the cationic peptide CL22, that transfects human monocyte-derived DCs much more efficiently than alternative nonviral agents. After CL22 transfection, DCs expressing antigens stimulated autologous T cells in vitro and elicited primary immune responses in syngeneic mice, in an antigen-specific manner. Injection of CL22-transfected DCs expressing a TAA, but not DCs pulsed with a TAA-derived peptide, protected mice from lethal challenge with tumor cells in an aggressive model of melanoma. The CL22 system is a fast and efficient alternative to viral vectors for engineering DCs for use in immunotherapy and research.     

Antitumor effect of pharmacologic ascorbate in the B16 murine melanoma model

Because 5-year survival rates for patients with metastatic melanoma remain below 25%, there is continued need for new therapeutic approaches. For some tumors, pharmacologic ascorbate treatment may have a beneficial antitumor effect and may work synergistically with standard chemotherapeutics. To investigate this possibility in melanoma, we examined the effect of pharmacologic ascorbate on B16-F10 cells. Murine models were employed to compare tumor size following treatment with ascorbate, and the chemotherapeutic agents dacarbazine or valproic acid, alone or in combination with ascorbate. Results indicated that nearly all melanoma cell lines were susceptible to ascorbate-mediated cytotoxicity. Compared to saline controls, pharmacologic ascorbate decreased tumor size in both C57BL/6 (P<0.0001) and NOD-scid tumor bearing mice (P<0.0001). Pharmacologic ascorbate was superior or equivalent to dacarbazine as an antitumor agent. Synergy was not apparent when ascorbate was combined with either dacarbazine or valproic acid; the latter combination may have additional toxicities. Pharmacologic ascorbate induced DNA damage in melanoma cells, as evidenced by increased phosphorylation of the histone variant, H2A.X. Differences were not evident in tumor samples from C57BL/6 mice treated with pharmacologic ascorbate compared to tumors from saline-treated controls. Together, these results suggest that pharmacologic ascorbate has a cytotoxic effect against melanoma that is largely independent of lymphocytic immune functions and that continued investigation of pharmacologic ascorbate in cancer treatment is warranted.     

Inhibition of angiogenesis by type I interferons in models of Kaposi's sarcoma

Kaposi's Sarcoma (KS) is a pathology which occurs with increased frequency and in a particularly aggressive form in AIDS patients. The HIV-1 Tat protein appears to be an important co-factor in the induction of the extensive neo-vascularization associated with AIDS-KS. Tat acts as a chemoattractant for endothelial cells in vitro, inducing both chemotactic and invasive responses. Several clinical trials have been performed testing the effectiveness of diverse biological agents in therapy of KS, among these the type I interferons. Type I IFNs have diverse biological functions besides their anti-viral activity, including anti-angiogenic properties. We have shown that IFN alpha and IFN beta are potent inhibitors of both primary and immortalized endothelial cell migration and morphogenesis in vitro as well as neo-angiogenesis induced by HIV-1 Tat in vivo. The inhibitory effect of IFN class I on HIV-Tat associated angiogenesis further supports its use as a therapy for epidemic Kaposi's sarcoma. The use of recombinant IFNs at the levels required to obtain a therapeutic effect are associated with side effects and toxicity, therefore we are now developing a gene therapy approach for constant and local delivery type I IFNs.     

New therapies in onco-hematology and new infectious risk factors

The biologic, clinical and therapeutic setting is nowadays such that risk factors for infectious complications are constantly changing and progressively increasing in patients suffering from onco-hematologic conditions. In addition to situations that are well known or that are gradually being recognized related both to the underlying disease and to treatment, such as neutropenia, neutrophil dysfunction, mucosal damage, concomitant monocytopenia and lymphopenia, abnormalities within the host cellular and humoral compartments, impairments in cytokine networks, alterations in T lymphocytes/tumor interactions, crosstalks between neoplastic cells and accessory cells, etc, over the last few years we are witnessing important changes in the overall management of patients with hematologic malignancies. Historically, the categories at risk were represented by patients with acute leukemia and patients undergoing an allogeneic stem cell transplant. In both, the likelihood of eradicating the disease requires necessarily a myeloablative therapeutic strategy, complicated in the allografted patients by the risks of graft-versus-host disease (GvHD), the required immunosuppressive treatment and the recently documented role that cytokines may play in the development of acute GvHD. Considerable changes have occurred in recent years. From the identification of "new" diseases at risk (e.g. lymphomas occurring in HIV+ individuals), to the progressive and constant increase in allotransplant procedures, to the development of new transplant procedures (cord blood, matched-unrelated or mismatched donor transplant, mini-transplant, the administration of donor lymphocytes), to the development of new drugs that can induce immunosuppression, to the clinical use of certain monoclonal antibodies (MoAb), to the combined use of chemotherapy plus MoAb. These developments are associated with other general considerations. Within these: 1) the growing use of ablative therapies in diseases for which for many years the approach has been less aggressive or indeed conservative; 2) the progressive recognition of categories of patients with unfavorable prognosis for whom an aggressive approach is required; 3) the constant improvement in mean life expectancy and "biologic" age of patients; thus, the progressive changes in the definition of "old age". Taken together, this has led, on the one hand, to an increase in the categories of onco-hematologic patients at risk of infective complications and to a major focus on the immune compartment of the affected patients, and, on the other hand, to an overall broadening of the infective scenario.     

Chemopreventive agent-induced modulation of death receptors

The goals of chemoprevention of cancer are to inhibit the initiation or suppress the promotion and progression of preneoplastic lesions to invasive cancer through the use specific natural or synthetic agents. Therefore, a more desirable and aggressive approach is to eliminate aberrant clones by inducing apoptosis rather than merely slowing down their proliferation. The increased understanding of apoptosis pathways has directed attention to components of these pathways as potential targets not only for chemotherapeutic but also for chemopreventive agents. Activation of death receptors triggers an extrinsic apoptotic pathway, which plays a critical role in tumor immunosurveillance. An increasing number of previously identified chemopreventive agents were found to induce apoptosis in a variety of premalignant and malignant cell types in vitro and in a few animal models in vivo. Some chemopreventive agents such as non-steroidal anti-inflammatory drugs, tritepenoids, and retinoids increase the expression of death receptors. Thus, understanding the modulation of death receptors by chemopreventive agents and their implications in chemoprevention may provide a rational approach for using such agents alone or in combination with other agents to enhance death receptor-mediated apoptosis as a strategy for effective chemoprevention of cancer.     

The Antihelmintic Drug Pyrvinium Pamoate Targets Aggressive Breast Cancer

WNT signaling plays a key role in the self-renewal of tumor initiation cells (TICs). In this study, we used pyrvinium pamoate (PP), an FDA-approved antihelmintic drug that inhibits WNT signaling, to test whether pharmacologic inhibition of WNT signaling can specifically target TICs of aggressive breast cancer cells. SUM-149, an inflammatory breast cancer cell line, and SUM-159, a metaplastic basal-type breast cancer cell line, were used in these studies. We found that PP inhibited primary and secondary mammosphere formation of cancer cells at nanomolar concentrations, at least 10 times less than the dose needed to have a toxic effect on cancer cells. A comparable mammosphere formation IC50 dose to that observed in cancer cell lines was obtained using malignant pleural effusion samples from patients with IBC. A decrease in activity of the TIC surrogate aldehyde dehydrogenase was observed in PP-treated cells, and inhibition of WNT signaling by PP was associated with down-regulation of a panel of markers associated with epithelial-mesenchymal transition. In vivo, intratumoral injection was associated with tumor necrosis, and intraperitoneal injection into mice with tumor xenografts caused significant tumor growth delay and a trend toward decreased lung metastasis. In in vitro mammosphere-based and monolayer-based clonogenic assays, we found that PP radiosensitized cells in monolayer culture but not mammosphere culture. These findings suggest WNT signaling inhibition may be a feasible strategy for targeting aggressive breast cancer. Investigation and modification of the bioavailability and toxicity profile of systemic PP are warranted.     

Protective effects of plant-derived natural products on renal complications

Diabetic nephropathy is the leading cause of renal failure worldwide. This debilitating disorder has several underlying pathophysiologic mechanisms, and therefore a variety of pharmacologic agents have been developed to prevent or treat diabetic nephropathy; however, synthetic drugs may possess unfavorable side effects. In response to this, the global use of herbal-based pharmacologic agents is increasing among diabetic patients. Numerous studies have reported therapeutic benefits of herbal-based compounds against diabetes-induced renal dysfunction. These agents can prevent renal dysfunction and improve renal function by blocking or suppressing deleterious pathways such as oxidative stress, inflammation, apoptosis, necrosis, and nitric oxide deprivation that lead to vascular injuries. In the current study, we have reviewed the beneficial properties of the most common herbal agents used in renal complications and diabetic nephropathy.     

Phase separation in phosphatidylcholine bilayers as a predictor of inhibition of blood platelet aggregation by amantadines

The ability of eleven amantadine derivatives to induce phase separation in dipalmitoyl phosphatidylcholine bilayers was studied by differential scanning calorimetry. The relative potency varied with the shape and size of the hydrocarbon cage. These agents also markedly inhibited blood platelet aggregation. The relative potencies of these compounds to induce phase separation showed a significant correlation ($\text{r = 0.70}$) with their platelet inhibitory activity suggesting that their pharmacologic action may be at the level of the platelet membrane. The effective concentration of the parent component amantadine is similar to its pharmacologic concentration suggesting its use as an anti-platelet drug.     

Double-helix formation of self-complementary chimeric oligonucleotides r(CG)nd(CG)3-n (n = 0, 1, 2, 3).

Double-helix formations of self-complementary chimeric hexanucleotides, r(CGCGCG), r(CGCG)d(CG), r(CG)d(CGCG), and d(CGCGCG), have been studied spectrophotometrically an thermodynamically in 1 mol dm-3 NaCl buffer. CD (circular dichroism) spectra showed that r(CGCGCG), r(CGCG)d(CG), and r(CG)d(CGCG) formed A-type double helix, while d(CGCGCG) formed B-type double helix. The stabilization energies of these helices at 37 degrees C obtained from UV melting analyses were 9.2 kcal mol-1 for r(CGCGCG), 8.2 kcal mol-1 for r(CGCG)d(CG), 6.8 kcal mol-1 for r(CG)d(CGCG), and 8.5 kcal mol-1 for d(CGCGCG), respectively.     

Arsenic trioxide and neuroblastoma cytotoxicity

The majority of aggressive forms of the childhood tumor neuroblastoma can with current treatment protocols not be cured and possess a major challenge in pediatric oncology. After initial rounds of chemotherapy, surgery and irradiation, which in most cases result in tumor regression, these aggressive neuroblastomas relapse and frequently develop drug resistance. As approximately 50% of the children with neuroblastoma have an aggressive form, there is a compelling demand for new treatment strategies. Arsenic trioxide has the capacity to kill multidrug-resistant neuro-blastoma cells in vitro and in vivo and the drug is currently being evaluated in clinical trials. In this report we discuss the background to the use of arsenic trioxide in cancer therapy and the currently known mechanisms by which arsenic trioxide kills human neuroblastoma cells.     

Focal Adhesion Kinase Inhibitors in Combination with Erlotinib Demonstrate Enhanced Anti-Tumor Activity in Non-Small Cell Lung Cancer

Blockade of epidermal growth factor receptor (EGFR) activity has been a primary therapeutic target for non-small cell lung cancers (NSCLC). As patients with wild-type EGFR have demonstrated only modest benefit from EGFR tyrosine kinase inhibitors (TKIs), there is a need for additional therapeutic approaches in patients with wild-type EGFR. As a key component of downstream integrin signalling and known receptor cross-talk with EGFR, we hypothesized that targeting focal adhesion kinase (FAK) activity, which has also been shown to correlate with aggressive stage in NSCLC, would lead to enhanced activity of EGFR TKIs. As such, EGFR TKI-resistant NSCLC cells (A549, H1299, H1975) were treated with the EGFR TKI erlotinib and FAK inhibitors (PF-573,228 or PF-562,271) both as single agents and in combination. We determined cell viability, apoptosis and 3-dimensional growth in vitro and assessed tumor growth in vivo. Treatment of EGFR TKI-resistant NSCLC cells with FAK inhibitor alone effectively inhibited cell viability in all cell lines tested; however, its use in combination with the EGFR TKI erlotinib was more effective at reducing cell viability than either treatment alone when tested in both 2- and 3-dimensional assays in vitro, with enhanced benefit seen in A549 cells. This increased efficacy may be due in part to the observed inhibition of Akt phosphorylation when the drugs were used in combination, where again A549 cells demonstrated the most inhibition following treatment with the drug combination. Combining erlotinib with FAK inhibitor was also potent in vivo as evidenced by reduced tumor growth in the A549 mouse xenograft model. We further ascertained that the enhanced sensitivity was irrespective of the LKB1 mutational status. In summary, we demonstrate the effectiveness of combining erlotinib and FAK inhibitors for use in known EGFR wild-type, EGFR TKI resistant cells, with the potential that a subset of cell types, which includes A549, could be particularly sensitive to this combination treatment. As such, further evaluation of this combination therapy is warranted and could prove to be an effective therapeutic approach for patients with inherent EGFR TKI-resistant NSCLC.     

Methylation of either cytosine in the recognition sequence CGCG inhibits ThaI cleavage of DNA.

ThaI (CGCG) sites which overlap HhaI (GCGC) sites in phi X174 and pBR322 DNA were methylated in vitro with HhaI methylase and S-adenosylmethionine to yield CGmCG, mCGCG or mCGmCG (5-methylcytosine, mC). Methylation of either cytosine in the ThaI recognition sequence rendered the DNA resistant to ThaI cleavage. Rat pituitary cell genomic DNA was digested with ThaI or 2 other known methylation-sensitive enzymes, AvaI or XhoI. After electrophoresis and ethidium bromide straining of the DNA, all 3 enzymes showed the infrequent DNA cleavage characteristic of methylation-sensitive enzymes. Comparison of pituitary growth hormone (GH) genes bearing strain-specific degrees of methylation showed the less methylated gene to be more frequently cut by either AvaI or ThaI. ThaI resistant sites in GH genes were cleaved by ThaI after exposing cells to 5-azacytidine, an inhibitor of DNA methylation. We conclude that ThaI is a useful restriction enzyme for the analysis of mC at CGCG sequences in eukaryotic DNA.     

Transdifferentiation of cancer stem cells into endothelial cells

Vasculogenic mimicry was first described as the unique ability of aggressive melanoma cells to express an endothelial phenotype and to form vessel-like networks in three dimensional cultures, “mimicking” the pattern of embryonic vascular networks and recapitulating the patterned networks seen in patients with aggressive tumors correlated with poor prognosis. Recent work shows the occurrence of alternative vasculogenic patterns is due to the presence of stem cell population (cancer stem cells, CSC) at least in melanoma and glioblastoma. In the present review the new perspectives to target vasculogenic mimicry for an anti-vascular treatment strategy and the possible use of AQP1 as target, are discussed. Interest in AQP1 as a target arises from the pivotal role it plays in the organisation of vascular network affecting the cytoskeleton.     

Cyclin degradation for cancer therapy and chemoprevention

Cancer is characterized by uncontrolled cell division resulting from multiple mutagenic events. Cancer chemoprevention strategies aim to inhibit or reverse these events using natural or synthetic pharmacologic agents. Ideally, this restores normal growth control mechanisms. Diverse classes of compounds have been identified with chemopreventive activity. What unites many of them is an ability to inhibit the cell cycle by specifically modulating key components. This delays division long enough for cells to respond to mutagenic damage. In some cases, damage is repaired and in others cellular damage is sufficient to trigger apoptosis. It is now known that pathways responsible for targeting G1 cyclins for proteasomal degradation can be engaged pharmacologically. Emergence of induced cyclin degradation as a target for cancer therapy and chemoprevention in pre-clinical models is discussed in this article. Evidence for cyclin D1 as a molecular pharmacologic target and biological marker for clinical response is based on experience of proof of principle trials.     

Calcium, calcium channels, and calcium channel antagonists

Voltage-dependent Ca2+ channels are an important pathway for Ca2+ influx in excitable cells. They also represent an important site of action for a therapeutic group of agents, the Ca2+ channel antagonists. These drugs enjoy considerable use in the cardiovascular area including angina, some arrhythmias, hypertension, and peripheral vascular disorders. The voltage-dependent Ca2+ channels exist in a number of subclasses characterized by electrophysiologic, permeation, and pharmacologic criteria. The Ca2+ channel antagonists, including verapamil, nifedipine, and diltiazem, serve to characterize the L channel class. This channel class has been characterized as a pharmacologic receptor, since it possesses specific drug-binding sites for both antagonists and activators and it is regulated by homologous and heterologous influences. The Ca2+ channels of both voltage- and ligand-regulated classes are likely to continue to be major research targets for new drug design and action.