Current Pharmaceutical Biotechnology - Volume 7, Issue 6, 2006

Multiple myeloma (MM) is a malignant proliferation of plasma cells and plasmacytoid cells in the bone marrow which is characterized nearly always by the presence in the serum and/or urine of a monoclonal immunoglobulin (Ig) or Ig fragment. MM is the second most common hematologic malignancy, accounting for 15,270 new cancer cases in the United States in the year 2004, and approximately 2% of cancer-related deaths. Several in vitro and animal model studies have demonstrated the importance of the bone marrow in promoting MM cell growth, survival, drug resistance, and migration within the bone marrow microenvironment and in extramedullary sites, and have already derived new molecules that target both MM cells and the bone marrow microenvironment. Thus, thalidomide and derivatives (Revlimid and the Actimid) and Velcade have transformed considerably the history of MM treatment. They have not to be considered as competitors but rather complementary agents whose impact will probably stem from their combination and their association with the intensive treatment. This issue of “Current Pharmaceutical Biotechnology” is a collection of reviews focused on “Novel agents for multiple myeloma treatment”. The goal has been to provide up-to-date reviews of benefit to a broad audience. We would like to express our appreciations to all colleagues for their excellent contributions. It is our hope that this issue serves as a platform to stimulate new ideas leading to new discoveries and the expansion of new frontiers in the field of multiple myeloma treatment.

Currently, Arsenic Trioxide (ATO) is considered the treatment of choice for patients with relapsed acute promyelocytic leukemia (APL). Recently, a durable remission with minimal toxicity by single agent ATO or ATO + ATRA in newly diagnosed APL was reported by different groups. These regimens have minimal toxicity and can be administered on an outpatient basis after remission induction, thus they could become a real, less toxic and more economic option to ATRA + anthracyclines in particular in low risk APL, or in patients that cannot undergo chemotherapy because of age or comorbid conditions and in patients that refuse chemotherapy. Significantly, these therapies are a successful attempt to cure a tumoral disease without chemotherapy. The results of clinical trials of ATO administration as single agent in multiple myeloma (MM) and myelodisplastic syndromes (MDS) were encouraging and showed clinical effects but they were not close to APL success. On the contrary, results of clinical trials to treat non-APL acute myeloid leukemia (AML) were disappointing. We suggest that a combination therapy with drugs targeting specific pro-survival molecules or capable to enhance pro-apoptotic pathways may lead to an improvement of ATO efficacy against hematological malignancies, in particular AML. Our pre-clinical studies showed that ATO is capable to induce cell death in acute leukemia cells but the apoptotic function is limited since it can induce also a mechanism of cell defense by activating pro-survival molecules such as MEK-ERK, Bcl-xL, Bcl-2. By combining ATO with specific MEK inhibitors, we demonstrated that the block of MEK-ERK phosphorylation, the induction of Bad de-phosphorylation, and activation of p53AIP1 apoptotic pathway interrupt the pro-survival mechanisms of ATO and kill the leukemic cells by apoptotic synergism. Our results provide an experimental basis for combined or sequential treatment with MEK inhibitors and ATO in AML. The renaissance of ATO as a drug in moderne medicine may be considered, together with ATRA success, a victory of empirical analysis, that had (and has) great impact on Chinese culture.

Multiple myeloma (MM) is an incurable malignancy of terminally differentiated B-cells accounting for approximately 1 to 2% of all human cancers. The development of MM is believed to be a multistep transformation process that leads to progressive accumulation of genetic alterations. The interaction between MM and bone marrow (BM) microenviroment triggers multiple proliferative and antiapoptotic signaling pathways. Here we discuss the current understanding of signaling pathways, and their potential implication in targeted therapies in MM.

Thalidomide and the analogues lenalidomide (CC-5013, Revlimid®) and CC-4047 (Actimid®) belong to the family of immunomodulatory drugs (IMiDs). These agents have anti-angiogenic properties, modulate TNFα and IL-12 secretion, co-stimulate T cells, increase NK cell toxicity and have direct anti-tumour effects. These characteristics have made of them promising drugs for treatment of relapsed, refractory and newly diagnosed MM. It seems that lenalidomide and CC-4047 are more powerful in inhibiting TNFα and have, except for myelosuppression, less side effects than Thal. Combination of IMiDs with dexamethasone, bortezomib and with chemotherapeutic agents are tested in numerous trials, which will help in determining the optimal combination and administration schedule of different molecules to take advantage of non-overlapping toxicities and synergisms between those agents.

Multiple myeloma (MM) is a plasma cell malignancy characterized by the high capacity to induce osteolytic bone lesions. Bone destruction in MM mainly depends on the increase of osteoclast formation and activity that occurs in close contact with myeloma cells infiltration. The histomorphometric studies, performed in MM patients, have demonstrated that MM patients with high plasma cell infiltrate are also characterized by a lower number of osteoblasts and a decreased bone formation that contributes, to the development of bone lesion. In the last years the progress in acknowledge of the pathophysiology of MM-induced osteolysis leaded to identify new therapeutics targets in MM bone disease and developed new drugs in the treatment of patients with skeletal involvement

Thalidomide (Thal) has antiangiogenic and immunomodulatory activity. Clinical research provided clear evidence that Thal is one of the most active drugs for the treatment of multiple myeloma leading to decrease of monoclonal protein of at least 50% in 30% of patients with relapsed or refractory multiple myeloma. Randomized trials based on a large body of evidence from phase II trials determined that Thal significantly increases total response rate in combination regimens (dexamethasone [Dex] and or chemotherapy) for relapsed as well as newly diagnosed patients. Thal also decreases time to response in combination therapy approaches. Thal has therefore been recognized by leading organizations as part of the treatment concept for patients with relapsed or refractory disease. Strict guidelines apply for the treatment and monitoring of Thal therapy to prevent the teratogenic effects of Thal and to monitor and prevent other potential adverse events as neuropathy and thrombosis. Additional randomized studies will now define the status of Thal for newly diagnosed patients and will be the basis for the approval in Europe and other countries world wide.

The ubiquitin-proteasome pathway (UPP) is the major non-lysosomal proteolytic system in the cytosol and nucleus of all eukaryotic cells. Bortezomib (also known as PS-341 and Velcade™) is a proteasome inhibitor, a novel class of cancer therapies. Bortezomib blocks multi-ubiquitinated protein degradation by inhibiting 26S proteasome activity, including regulating cell cycle, anti-apoptosis, and inflammation, as well as immune surveillance. In multiple myeloma (MM) cells, bortezomib directly induces cell stress response followed by activation of c-Jun NH2 terminal kinase (JNK)/stress-activated protein kinase (SAPK), and triggers caspase-dependent apoptosis of tumor cells. Recent clinical studies demonstrated that bortezomib had remarkable anti-tumor activity in refractory and relapsed MM, providing the basis to approval by FDA. Its anti-tumor activities earlier in the course, in combination therapies, and in other malignancies is ongoing.

Multiple myeloma (MM) is a B-cell malignancy characterized by an accumulation of long-lived neoplastic plasma cells (PC) within the bone marrow (BM). Novel treatments are not only targeting myeloma cells but also directly interfere with myeloma-stromal cell interactions, interrupting signal transduction pathways. Farnesyltransferase inhibitors (FTIs) and rapamycin represent novel classes of signal transduction inhibitors targeting principally Ras/MAPK and PI3K/Akt pathway. Pre-clinical and early clinical reports are presented in this study.

This special issue of Current Pharmaceutical Biotechnology deals with an exciting topic: &ldquoEssential Fatty Acids” and their implications for human health. Essential fatty acids (EFAs) are the main constituent of the phospholipid component of all cell membranes in the human body. EFAs, as it name implies, are essential for human survival but cannot be synthesized by the human body and hence, have to be obtained in our diet. The two EFAs are linoleic acid (LA) and -linolenic acid (ALA). Both LA and ALA form precursors to several of their long chain metabolites. Some of the important molecules that are formed from EFAs and their long-chain metabolites include: various eicosanoids, lipoxins, resolvins, and protectins. These molecules have several important actions on vascular tissue, platelets, leukocytes, macrophages, bronchial smooth muscle, myocardium, kidney, brain, and other cells and tissues in the body. Depending on the local tissue concentration and the type of metabolite formed from EFAs, they can have useful and harmful actions. For instance, excess formation of leukotrienes may produce inflammation, bronchospasm and thus may cause bronchial asthma. On the other hand, formation of appropriate amounts of lipoxins and resolvins may help in the resolution of inflammation and healing of wounds. In addition, EFAs may interact with nitric oxide and form nitrolipids that have potent biological actions. EFAs and their metabolites seem to have an important role in brain growth and development and memory formation and consolidation, participate in a variety of physiological and pathological processes. In this issue, the metabolism, actions and uses of EFAs and their metabolites has been outlined by various authors. I hope that the topics discussed will be useful to many of the readers.

Studies showed that gamma-linolenic acid (GLA) and its derivatives have the potential to be anti-cancer molecules. In vitro, in vivo and limited clinical studies showed that GLA has selective tumoricidal action with little or no side effects. The mechanism of its action appears to be by inducing apoptosis of tumor cells by augmenting free radical generation only in the tumor cells but not normal cells. Intra-arterial injection of a lithium salt derivative of GLA demonstrated its ability to selectively occlude tumor-feeding vessels. Since GLA is an endogenous naturally occurring molecule and has no significant side effects, it calls for more studies to exploit its potential as a novel anti-cancer drug.

Essential fatty acids (EFAs): cis-linoleic acid (LA) and -linolenic acid (ALA) are essential for humans and their deficiency is rare in humans due to their easy availability in diet. EFAs are metabolized to their respective long-chain metabolites: dihomo-gamma-linolenic acid (DGLA), and arachidonic acid (AA) from LA; and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from ALA. Some of these long-chain metabolites form precursors to respective prostaglandins (PGs), thromboxanes (TXs), and leukotrienes (LTs), lipoxins (LXs) and resolvins. EFAs and their metabolites may function as endogenous angiotensin converting enzyme and HMG-CoA reductase inhibitors, nitric oxide enhancers, anti-hypertensives, and anti-atherosclerotic molecules. EFAs react with nitric oxide (NO) to yield respective nitroalkene derivatives that have cell-signaling actions via ligation and activation of peroxisome proliferator-activated receptors (PPARs). In several diseases such as obesity, hypertension, diabetes mellitus, coronary heart disease, alcoholism, schizophrenia, Alzheimer's disease, atherosclerosis, and cancer the metabolism of EFAs is altered. Thus, EFAs and their derivatives have significant clinical implications.

The expression and activity of Fatty Acid Synthase (FASN; the sole enzyme capable of the reductive de novo synthesis of long-chain fatty acids from acetyl-CoA, malonyl-CoA, and nicotinamide adenine dinucleotide phosphate - NADPH-) is extremely low in nearly all nonmalignant adult tissues, whereas it is significantly up-regulated or activated in many cancer types, thus creating the potential for a large therapeutic index. Since the pioneering observation that inhibition of FASN activity by the mycotoxin cerulenin preferentially kills cancer cells and retards the growth of tumors in xenografts models, numerous in vitro and in vivo studies have confirmed the potential of FASN as a target for antineoplastic intervention. Other FASN inhibitors such as the cerulenin derivative C75, the β-lactone orlistat, the green tea polyphenol epigallocatechin-3-gallate (EGCG) and other naturally occurring flavonoids (i.e., luteolin, quercetin, and kaempferol), as well as the antibiotic triclosan, have been identified and have been shown to limit cancer cell growth by inducing apoptotic cell death. Though the exact mode of action of these FASN inhibitors is under discussion, it has been revealed that depletion of end-product fatty acids, toxic intracellular accumulation of supra-physiological concentrations of the FASN substrate malonyl-CoA and/or limited membrane synthesis and/or functioning by altered production of phospholipids partitioning into detergent-resistant membrane microdomains (lipid raft-aggregates), can explain, at least in part, the cytostatic, cytotoxic as well as the apoptotic effects occurring upon pharmacological inhibition of FASN activity in cancer cells. Moreover, several cancer-associated molecular features including nonfunctioning p53, overexpression of the Her-2/neu (erbB-2) oncogene, and hyperactivation of the PI-3'K down-stream effector protein kinase B (AKT), appear to determine an exacerbated sensitivity to FASN inhibition-induced cancer cell death. Although few of these inhibitors are expected to be &ldquoexclusively” selective for FASN, the potential of FASN as a target for antineoplastic intervention has eventually been confirmed by RNA interference (RNAi)-knockdown of FASN. Certainly, future studies should definitely elucidate the ultimate biochemical link between FASN inhibition and cancer cell death. Although the combination of FASN structural complexity and until recently the lack of X-ray crystallography data of mammalian FASN created a significant challenge in the exploitation of FASN as a valuable target for drug development, it is hoped that the improvement in the selectivity and potency of forthcoming novel FASN-targeted small molecule inhibitors by taking advantage, for instance, of the recent 4.5 Å resolution X-ray crystallographic map of mammalian FASN, will direct the foundation of a new family of chemotherapeutic agents in cancer history.

The final proof about the specific mechanisms by which the different components of olive oil, the principal source of fat in a typical &ldquoMediterranean diet&rdquo, exert their potential protective effects on the promotion and progression of several human cancers requires further investigations. A recent discovery that dietary fatty acids can interact with the human genome by regulating the amount and/or activity of transcription factors has opened a whole new line of research aimed to molecularly corroborate the ant-cancer benefits of the olive oil-based Mediterranean diet and the underlying mechanisms. Our most recent findings reveal that oleic acid (OA; 18:1n-9), the main olive oil's monounsaturated fatty acid, can suppress the overexpression of HER2 (erbB-2), a well-characterized oncogene playing a key role in the etiology, invasive progression and metastasis in several human cancers. First, exogenous supplementation with physiological concentrations of OA significantly down-regulates HER2-coded p185Her-2/neu oncoprotein in human cancer cells naturally harboring amplification of the HER gene. Second, OA exposure specifically represses the transcriptional activity of the human HER2 gene promoter in tumor-derived cell lines naturally exhibiting HER2 gene amplification and p185Her-2/neu protein overexpression but not in cancer cells expressing physiological levels of HER2. Third, OA treatment induces the upregulation of the Ets protein PEA3 (a transcriptional repressor of the HER2 gene promoter) solely in cancer cells naturally displaying HER2 gene amplification. Fourth, HER2 gene promoter bearing a PEA3 site-mutated sequence cannot be negatively regulated by OA, while treatment with OA fails to repress the expression of a human full-length HER2 cDNA controlled by a SV40 viral promoter. Fifth, OA-induced inhibition of HER2 promoter activity does not occur if HER2 gene-amplified cancer cells do no concomitantly exhibit high levels of Fatty Acid Synthase (FASN; Oncogenic antigen- 519) as specific depletion of FASN, which itself similarly suppresses HER2 overexpression by inducing PEA3-dependent repression of HER2 gene promoter, strongly antagonizes the inhibitory effects of OA on HER2 gene promoter activity. Considering that OA treatment efficiently blocks FASN activity and down-regulates FASN protein expression, it is reasonable to suggest that an accumulation of supra-physiological concentrations of the FASN substrate malonyl-CoA, due to its reduced utilization by FASN in the presence of exogenous OA, appears to act as an indicator of &ldquocell fuel&rdquo availability capable to suppress HER2 expression via formation of inhibitory &ldquoPEA3 protein-PEA3 DNA binding site&rdquo complexes on the endogenous HER2 promoter. Indeed, malonyl-CoA on its own dramatically decreases HER2 promoter activity, while OA or malonyl-CoA similarly up-regulates PEA3 gene promoter activity. This previously unrecognized ability of OA to directly affect the expression of a cluster of interrelated human cancer genes (i.e., HER2, FASN and PEA3) should open a new line of research aimed to explore the anti-cancer effects of OA. Certainly, an appropriate dietary intervention reproducing this prominent anti-oncogenic feature of the &ldquoMediterranean diet&rdquo must be carried out in animal models and human pilot studies in the future. Only then we will know whether the old &ldquoMediterranean dietary traditions&rdquo will become a new molecular approach in the management of cancer disease.

The global incidence of atopic eczema is escalating. While new treatment options are becoming available, previous treatments with certain confirmed benefits are still worth investigating as safe and effective therapies. One such treatment, Efamol® evening primrose oil (EPO), was proven efficacious in a 1989 meta-analysis of randomized, doubleblind, placebo-controlled clinical trials. A decade of further testing and subsequent independent reanalysis of 26 clinical studies including 1207 patients presented here, establishes that Efamol® EPO has a simultaneous, beneficial effect on itch/pruritis, crusting, oedema and redness (erythema) that becomes apparent between 4 and 8 weeks after treatment is initiated. However, the magnitude of this effect is reduced in association with increasing frequency of potent steroid use. This and other confounding variables that are now being reported in the literature may account for historically reported inconsistent patient response. Recent research has uncovered unique complexities in fatty acid metabolism and immune response in the atopic condition beyond those previously reported and may well have identified a subcategory of nonresponders and has helped established those that can consistently derive significant benefit. Further research is needed to provide a better understanding of the physiology behind this complex disorder and the beneficial role that fatty acids can play in its development and management. Conclusion: Efamol® EPO has a simultaneous, beneficial effect on itch/pruritis, crusting, oedema and redness (erythema) that becomes apparent between 4 and 8 weeks after treatment is initiated. However, the magnitude of this effect is reduced in association with increasing frequency of potent steroid use.

The applications of 'omics' (genomics, transcriptomics, proteomics and metabolomics) technologies in nutritional studies have opened new possibilities to understand the effects and the action of different diets both in healthy and diseased states and help to define personalized diets and to develop new drugs that revert or prevent the negative dietary effects. Several single nucleotide polymorphisms have already been investigated for potential gene-diet interactions in the response to different lipid diets. It is also well-known that besides the known cellular effects of lipid nutrition, dietary lipids influence gene expression in a tissue, concentration and age-dependent manner. Protein expression and post-translational changes due to different diets have been reported as well. To understand the molecular basis of the effects and roles of dietary lipids high-throughput functional genomic methods such as DNA- or protein microarrays, high-throughput NMR and mass spectrometry are needed to assess the changes in a global way at the genome, at the transcriptome, at the proteome and at the metabolome level. The present review will focus on different high-throughput technologies from the aspects of assessing the effects of dietary fatty acids including cholesterol and polyunsaturated fatty acids. Several genes were identified that exhibited altered expression in response to fish-oil treatment of human lung cancer cells, including protein kinase C, natriuretic peptide receptor-A, PKNbeta, interleukin-1 receptor associated kinase- 1 (IRAK-1) and diacylglycerol kinase genes by using high-throughput quantitative real-time PCR. Other results will also be mentioned obtained from cholesterol and polyunsaturated fatty acid fed animals by using DNA- and protein microarrays.

Inflammation plays an important role in health and disease. Most of the chronic diseases of modern society, including cancer, diabetes, heart disease, arthritis, Alzheimer's disease, etc. have inflammatory component. At the same time, the link between diet and disease is also being recognized. Amongst dietary constituents, fat has gained most recognition in affecting health. Saturated and trans fatty acids have been implicated in obesity, heart disease, diabetes and cancer while polyunsaturated fatty acids (PUFAs) generally have a positive effect on health. The PUFAs of omega-3 and omega-6 series play a significant role in health and disease by generating potent modulatory molecules for inflammatory responses, including eicosanoids (prostaglandins, and leukotrienes), and cytokines (interleukins) and affecting the gene expression of various bioactive molecules. Gamma linolenic acid (GLA, all cis 6, 9, 12-Octadecatrienoic acid, C18:3, n- 6), is produced in the body from linoleic acid (all cis 6,9-octadecadienoic acid), an essential fatty acid of omega-6 series by the enzyme delta-6-desaturase. Preformed GLA is present in trace amounts in green leafy vegetables and in nuts. The most significant source of GLA for infants is breast milk. GLA is further metabolized to dihomogamma linlenic acid (DGLA) which undergoes oxidative metabolism by cyclooxygenases and lipoxygenases to produce anti-inflammatory eicosanoids (prostaglandins of series 1 and leukotrienes of series 3). GLA and its metabolites also affect expression of various genes where by regulating the levels of gene products including matrix proteins. These gene products play a significant role in immune functions and also in cell death (apoptosis). The present review will emphasize the role of GLA in modulating inflammatory response, and hence its potential applications as an anti-inflammatory nutrient or adjuvant.