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OPEN ACCESS PLUS
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Contents
12(7): Pp. 857 - 872
Z. Mihaly, Z. Sztupinszki, P. Surowiak and B. Gyorffy
[Open Access Plus] |
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Chemotherapy and immunotherapy failed to deliver decisive results in the systemic treatment of metastatic renal cell carcinoma. Agents representing the current standards operate on members of the RAS signal transduction pathway. Sunitinib (targeting vascular endothelial growth factor), temsirolimus (an inhibitor of the mammalian target of rapamycin - mTOR) and pazopanib (a multi-targeted receptor tyrosine kinase inhibitor) are used in the first line of recurrent disease. A combination of bevacizumab (inhibition of angiogenesis) plus interferon α is also first-line therapy. Second line options include everolimus (another mTOR inhibitor) as well as tyrosine kinase inhibitors for patients who previously received cytokine. We review the results of clinical investigations focusing on survival benefit for these agents. Additionally, trials focusing on new agents, including the kinase inhibitors axitinib, tivozanib, dovitinib and cediranib and monoclonal antibodies including velociximab are also discussed. In addition to published outcomes we also include follow-up and interim results of ongoing clinical trials. In summary, we give a comprehensive overview of current advances in the systemic treatment of metastatic renal cell carcinoma.
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12(7): Pp. 838 - 846
P. Tagliaferri, M. Rossi, M. T. Di Martino, N. Amodio, E. Leone, A. Gulla, A. Neri and P. Tassone
[Open Access Plus] |
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MicroRNAs (miRNAs) recently emerged with a key role in multiple myeloma (MM) pathophysiology and are considered important regulators of MM cell growth and survival. Since miRNAs can act either as oncogenes or tumour suppressors, the potential of targeting the miRNA network arises as a novel therapeutic approach for human cancer. Potential strategies based on miRNA therapeutics basically rely on miRNA inhibition or miRNA replacement approaches and take benefit respectively from the use of antagomirs or synthetic miRNAs as well as from lipid-based nanoparticles which allow an efficient miRNA-delivery. The availability of experimental in vivo platforms which recapitulate the growth of MM cells within the specific human bone marrow microenvironment in immunocompromised mice (SCID-hu and SCID-synth-hu) provides powerful systems for development of miRNA-based therapeutics in MM. Preliminary findings on the anti-MM activity of synthetic miRNAs in such experimental models offer a proof-of-principle that miRNA therapeutics is a promising opportunity for this still incurable disease representing the rationale for a new venue of investigation in this specific field.
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12(7): Pp. 814 - 822
P. Tassone, P. Neri, R. Burger, M. T. Di Martino, E. Leone, N. Amodio, M. Caraglia and P. Tagliaferri
[Open Access Plus] |
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Mouse models of multiple myeloma (MM) are basic tools for translational research and play a fundamental role in the development of new therapeutics against plasma cell malignancies. All available models, including transplantable murine tumors in syngenic mice, xenografts of established human cell lines in immunocompromised mice and transgenic models that mirror specific steps of MM pathogenesis, have demonstrated some weaknesses in predicting clinical results, particularly for new drugs targeting the human bone marrow microenvironment (huBMM). The recent interest to models recapitulating the in vivo growth of primary MM cells in a human (SCID-hu) or humanized (SCID-synth-hu) host recipient has provided powerful platforms for the investigation of new compounds targeting MM and/or its huBMM. Here, we review and discuss strengths and weaknesses of the key in vivo models that are currently utilized in the MM preclinical investigation.
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11(7): Pp. 826 - 836
B. B. Cheung and G. M. Marshall
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Following the discovery that defective retinoid signaling directly contributes to tumorigenesis, and, that retinoids have an anti-cancer effect in vitro and in vivo, retinoids have become part of the routine care in children with neuroblastoma at the stage of minimal residual disease. However, many patients still relapse following retinoid therapy, demonstrating the need for more effective retinoids and better assays to predict retinoid sensitivity in cancer cells. Recent evidence suggests that the copper metabolism gene, ATP7A, is retinoid-regulated and an important component of the retinoic acid receptor β (RARβ) anticancer effect in neuroblastoma cells. To highlight and further develop the concept of using ATP7A as a target in retinoid therapy, and combination therapy with copper chelators in neuroblastoma, the current literature and abstracts related to the clinical application of retinoids, the function of ATP7A and the clinical application of copper chelators are summarized. We propose that strategies targeting the copper export protein, ATP7A, in combination therapy with retinoids and copper depletion therapy, may have great therapeutic potential in the clinical treatment of neuroblastoma and other malignancies.
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10(8): Pp. 824 - 833
A. J. Weickhardt, N. C. Tebbutt and J. M. Mariadason
[Open Access Plus] |
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Mutations in K-Ras are observed in approximately 40% of colon tumours. This has significant implications for predicting likelihood of response to the antibody-based EGFR inhibitors, cetuximab and panitumumab, with K-Ras mutant patients now clearly shown to be inherently resistant to these agents. Alternative treatment strategies for K-Ras mutant patients are therefore urgently needed. Farnesyltransferase inhibitors, developed to inhibit K-Ras, have to-date been largely unsuccessful. However, a number of agents which target signaling components in the MAPK and PI3K pathways downstream of mutant K-Ras are currently being evaluated in clinical trials and will be discussed. A further clinical concern is that K-Ras wild type patients who initially respond to EGFR inhibitors eventually develop acquired resistance to these agents and experience tumour progression. Studies from the use of related agents in other disease settings as well as pre-clinical studies provide important insights into mechanisms by which this may occur. While no evidence presently exists for somatic mutations as a basis for acquired resistance to EGFR inhibitors in colon cancer, several studies implicate upregulation and signaling via other Her family members, c-Met, IGFR and Src. Upregulation of the pro-angiogenic factor, VEGF, is also a possible mechanism of acquired resistance. This review discusses drugs currently in clinical trials that may potentially achieve more efficient and prolonged targeting of the EGFR pathway by overcoming these mechanisms of resistance.
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10(2): Pp. 155 - 167
A. K. Gandhi, J. Kang, L. Capone, A. Parton, L. Wu, L. H. Zhang, D. Mendy, A. Lopez-Girona, T. Tran, L. Sapinoso, W. Fang, S. Xu, G. Hampton, J. B. Bartlett and P. Schafer
[Open Access Plus] |
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To determine the effect of dexamethasone on the antimyeloma effects of lenalidomide, we tested in vitro proliferation, tumor suppressor gene expression, caspase activity, cell cycling, and apoptosis levels in a series of multiple myeloma (MM) and plasma cell leukemia cell lines treated with lenalidomide and dexamethasone, alone or in combination. The effect of dexamethasone on the immunomodulatory activities of lenalidomide such as T cell and natural killer (NK) cell activation was measured via interleukin [IL]-2 production, and interferon-γ and granzyme B production respectively. Lenalidomide inhibited proliferation in most cell lines tested, and this effect was enhanced by dexamethasone. This effect was observed in MM cells containing the high-risk cytogenetic abnormalities t(4;14), t(14;16), del17p, del13, and hypodiploidy. Mechanistically, lenalidomide plus dexamethasone synergistically induced expression of the tumor suppressor genes Egr1, Egr2, Egr3, p15, p21, and p27 in MM cell lines and MM patient cells. The combination activated caspases 3, 8, and 9 and induced cell cycle arrest and apoptosis. Lenalidomide alone increased T cell production of IL-2, and NK cell production of interferon-γ and granzyme B. Notably, dexamethasone antagonized these immunostimulatory effects of lenalidomide in a dose-dependent manner. These data further elucidate the mechanism of action of lenalidomide and dexamethasone in MM, and suggest that use of low-dose dexamethasone with lenalidomide may retain the antiproliferative effect of lenalidomide while permitting greater immunomodulatory effects of this combination regimen.
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9(4): Pp. 572 - 594
Qi Zhao Wang, William Xu, Nagy Habib and Ruian Xu
[Open Access Plus] |
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Lung cancer is the leading cause of death from cancer in the world. Although the molecular network of lung carcinogenesis has been partly known at the levels of genes and proteins, and personalized therapy based on the genetic changes has made considerable progress in the last decade, the high mortality rate is not markedly changed. MicroRNAs (miRNAs), a class of short endogenous RNAs, acting as post-transcriptional regulators of gene expression, are similar with siRNAs in both the biosynthesis and the function steps. While, miRNAs mostly silence gene expression by binding imperfectly matched sequences in the 3 UTR of target mRNA, which is different with siRNAs by targeting ORF of mRNA with a perfectly complementary manner. miRNAs have multiple functions in lung development, and abnormal expression of miRNAs could lead to lung tumorigenesis. The different expression profiles of miRNAs in lung cancer, and the stability of miRNAs in serum, all together make them as new potentially clinical biomarkers for diagnosis and prognosis. Moreover, miRNAs may serve as either novel potential targets acting directly as oncogenes (e.g. miR-17-92 cluster) or directly therapeutic molecules working as tumor suppressor genes (e.g. let-7 family). RNAi technology based on miRNAs has many advantages over siRNAs, such as in vivo stability, highly RNA promoter-compatibility and no overt toxicity. Eventually, it might overcome the present disadvantages and become a good candidate for lung cancer therapy.
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8(4): Pp. 243 - 252
Kazumori Arai, Sachiko Takano, Takumi Teratani, Yasuhiro Ito, Toshihiro Yamada and Ryushi Nozawa
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S100 protein A8 and A9 naturally form a stable heterocomplex. Recently, we have proved that S100A9 overexpression in various adenocarcinomas is associated with poor tumor differentiation. In this study, we examined the relationship between the expression of each protein and the pathological parameters that reflect the aggressiveness of carcinoma, in invasive ductal carcinoma (IDC) of the breast. Serial paraffin-embedded tissue sections from 101 IDC cases were immunostained with respective monoclonal antibodies, and the results were as follows: 1) A positive correlation of immunoreactivity between S100A8 and S100A9 was noticed (r=0.873 and P < 0.0001); 2) The percentage of S100A9- positive tumor cells was higher than that of S100A8-positive tumor cells (P < 0.001), and S100A8 alone was not detected in any case; 3) Overlap between S100A8 and S100A9 staining patterns was found in the corresponding tissue areas, but S100A9 positivity was also observed in S100A8-negative tumor cells; 4) The immunopositivity for each protein also correlated with the mitotic activity, MIB-1 index, HER2 overexpression, node metastasis, and poor pT categories and pStage (P < 0.05); 5) Co-expression of both proteins was associated with poor tumor differentiation, vessel invasion, node metastasis, and poor pStage (P < 0.05). Furthermore, co-expression of the proteins was also observed in MCF-7 cells, and it was suggested that the immunolocalization is related with cell cycle. Our conclusions are as follows: 1) It is suggested that S100A8 is S100A9-dependently expressed and acquires the protein stability by S100A8/A9 heterocomplex formation; 2) S100A8 and S100A9 overexpression should be considered marker of poor prognosis in IDC.
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7(5): Pp. 465 - 474
Leena Hilakivi-Clarke
[Open Access Plus] |
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Findings with experimental rodent models reveal that exposures to dietary factors during the in utero and pubertal periods when the mammary gland is undergoing extensive modeling and re-modeling, alter susceptibility to develop mammary tumors. Similar observations have been made in humans: childhood exposure to genistein in soy or to some other bioactive food components reduces later breast cancer risk, although they may have no effect if consumed during adulthood. Thus, food components may be more effective in affecting cancer risk in some periods of life than others. Many of these dietary exposures modify fetal and postnatal hormonal environment, including changing the concentrations of estrogens and leptin. The hormonal alterations then may induce persistent epigenetic changes by affecting gene promoter regions or by inducing histone modifications that affect chromatin transcription. The targets of epigenetic changes are likely to be the terminal end buds (TEBs), the structures where carcinogen-induced mammary tumors in rats and mice are initiated. More specifically, the site of these changes in TEBs may be the stem cells and their niche; this might explain how an exposure early in life affects the risk of breast cancer decades later. Similar structures in women, called terminal ductal lobular units, are the sites where most human breast cancers rise. According to this hypothetical model, cancer is initiated only when the epigenetically altered cells are exposed to carcinogens/radiation, etc. during adult life. In a “normal” stem cell or its niche, cancer initiating exposures do not necessarily cause cancer, because the cells can either repair the damage or undergo apoptosis. Thus, the most likely molecular targets of early life dietary exposures are genes that regulate DNA adduct formation, repair DNA damage or induce apoptosis, such as genes affecting cellular metabolism, tumor suppressor genes or genes promoting cell survival. It is possible that some of these epigenetic changes also explain why the number of TEBs generally, but not always, correlates with breast cancer risk. This hypothesis may imply that adult intake of some bioactive dietary components reduces cancer risk increased by early life dietary exposures or inhibits tumor growth by reversing epigenetic changes in various molecular targets.
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6(5): Pp. 409 - 431
J. Shao, B. Zhou, Bernard Chu and Y. Yen
[Open Access Plus] |
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Ribonucleotide reductase (RR) is a multisubunit enzyme responsible for the reduction of ribonucleotides to their corresponding deoxyribonucleotides, which are building blocks for DNA replication and repair. The key role of RR in DNA synthesis and cell growth control has made it an important target for anticancer therapy. Increased RR activity has been associated with malignant transformation and tumor cell growth. Efforts for new RR inhibitors have been made in basic and translational research. In recent years, several RR inhibitors, including Triapine, Gemcitabine, and GTI-2040, have entered clinical trial or application. Furthermore, the discovery of p53R2, a p53-inducible form of the small subunit of RR, raises the interest to develop subunit-specific RR inhibitors for cancer treatment. This review compiles recent studies on (1) the structure, function, and regulation of two forms of RR; (2) the role in tumorigenesis of RR and the effect of RR inhibition in cancer treatment; (3) the classification, mechanisms of action, antitumor activity, and clinical trial and application of new RR inhibitors that have been used in clinical cancer chemotherapy or are being evaluated in clinical trials; (4) novel approaches for future RR inhibitor discovery.
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6(2): Pp. 123 - 133
A. Nardin, M. L. Lefebvre, K. Labroquere, O. Faure and J. P. Abastado
[Open Access Plus] |
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About one third of osteosarcoma patients develop lung metastasis refractory to chemotherapy. Recent studies indicate that biological response modifiers activating the patients immune system may help controlling minimal residual disease via pathways distinct from those used by cytotoxic drugs, and therefore prove effective against tumor resistance. Muramyl tripeptide phosphatidylethanolamine (MTP-PE) is a synthetic lipophilic glycopeptide capable of activating monocytes and macrophages to a tumoricidal state. When intercalated in multilamellar liposomes (L-MTP-PE) and injected intravenously, it targets lung, liver, and spleen macrophages. Therapeutic activity of L-MTP-PE was demonstrated in several preclinical models of experimental lung metastasis and in clinical trials in dogs with osteosarcoma. Although macrophage activation was shown to be directly involved in the in vivo anti-metastatic activity of this molecule, cytokine and chemokine secretion by activated macrophages could induce recruitment and stimulation of other immune cells, which may in turn indirectly contribute to the anti-tumor effect. L-MTP-PE has undergone clinical development in humans. In early trials, most side effects of L-MTP-PE were minimal. L-MTP-PE showed signs of efficacy in treatment of patients with recurrent osteosarcoma and the encouraging results from phase II studies led to a phase III trial conducted by the Childrens Oncology Group in patients with newly diagnosed high-grade osteosarcoma. Patients were treated with or without L-MTP-PE in combination with multi-drug chemotherapy in adjuvant setting; significantly higher overall survival and disease-free survival were observed in the group receiving L-MTP-PE.
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