Autophagy and cancer therapy cardiotoxicity: From molecular mechanisms to therapeutic opportunities

Cardiotoxicity is a major drawback of anticancer therapies, often hindering optimal management of cancer. Among the most cardiotoxic agents are anthracyclines (AC) that, despite being cardiotoxic, are highly effective in the treatment of a wide variety of cancers, spanning from hematological malignancies to solid tumors. Modern imaging techniques can identify patients at risk of developing cardiotoxicity, but treatment options are still limited and ineffective, partly because the molecular mechanisms underlying AC cardiac side effects are still incompletely understood. Although AC cardiotoxicity was initially ascribed to the trigger of cell-damaging oxidative stress, antioxidants fail to prevent anthracycline-induced cardiotoxicity (AIC), suggesting the involvement of additional mechanisms. Among these, the cellular recycling process, named autophagy, recently emerged to play a key role in AIC, but whether autophagy activation is beneficial or detrimental in this context is still controversial. This review will summarize recent evidence on the role of autophagy in AIC in the attempt to reconcile the controversial findings in the field. Finally, we will describe major regulator of cardiac autophagy that may represent good candidates for therapeutic intervention in AIC.     

Iron homeostasis and tumorigenesis: molecular mechanisms and therapeutic opportunities

Excess iron is tightly associated with tumorigenesis in multiple human cancer types through a variety of mechanisms including catalyzing the formation of mutagenic hydroxyl radicals, regulating DNA replication, repair and cell cycle progression, affecting signal transduction in cancer cells, and acting as an essential nutrient for proliferating tumor cells. Thus, multiple therapeutic strategies based on iron deprivation have been developed in cancer therapy. During the past few years, our understanding of genetic association and molecular mechanisms between iron and tumorigenesis has expanded enormously. In this review, we briefly summarize iron homeostasis in mammals, and discuss recent progresses in understanding the aberrant iron metabolism in numerous cancer types, with a focus on studies revealing altered signal transduction in cancer cells.     

Molecular pathogenesis and therapeutic targets in epithelial ovarian cancer

Ovarian cancer, the most aggressive gynecologic cancer, is the foremost cause of death from gynecologic malignancies in the developed world. Two primary reasons explain its aggressive behavior: most patients present with advanced disease at diagnosis, and die of recurrences from disease that has become resistant to conventional chemotherapies. In this paper on epithelial ovarian cancer (EOC), we will review molecular alterations associated with the few precursor lesions identified to date, followed by the more commonly recognized processes of de novo carcinogenesis, metastasis, and the development of chemoresistance. We will propose a unifying model of ovarian epithelial tumorigenesis that takes into account various hypotheses. We will also review novel approaches to overcome the major problem of chemoresistance in ovarian cancer. Finally, we will discuss advances and new challenges in the development of mouse model systems to investigate EOC precursor lesions, progression, metastasis, and chemoresistance.     

Apolipoprotein E and Alzheimer's disease: molecular mechanisms and therapeutic opportunities

Multiple genetic and environmental factors are likely to contribute to the development of Alzheimer's disease (AD). The most important known risk factor for AD is presence of the E4 isoform of apolipoprotein E (apoE). Epidemiological studies demonstrated that apoE4 carriers have a higher risk and develop the disease and an early onset. Moreover, apoE4 is the only molecule that has been associated with all the biochemical disturbances characteristic of the disease: amyloid-beta (Abeta) deposition, tangle formation, oxidative stress, lipid homeostasis deregulation, synaptic plasticity loss and cholinergic dysfunction. This large body of evidence suggest that apoE is a key player in the pathogenesis of AD. This short review examines the current facts and hypotheses of the association between apoE4 and AD, as well as the therapeutic possibilities that apoE might offer for the treatment of this disease.     

Prostate tumor-stroma interaction: molecular mechanisms and opportunities for therapeutic targeting

Maintenance of cell and tissue homeostasis is dependent upon the dynamic balance of cell proliferation, differentiation, and apoptosis through interactions between cells and their microenvironment. The unique prostatic cellular phenotypes are induced and maintained by interaction between epithelium and adjacent stroma through intimate intercellular signaling pathways. In this article, we summarize current advances in the tumor-stroma interaction and its biologic and therapeutic implications. We specifically emphasize current studies of the possible factors driving the "vicious cycle" between stroma and emerging prostate tumor epithelial cells that may be responsible for carcinogenesis and metastasis to bone. Stroma responds both genotypically and phenotypically to tumor epithelium upon co-culture under 3-D conditions. Likewise, the emerging carcinoma responds to stromal signals that drive progression to malignancy. A vicious cycle mediated by soluble and insoluble molecules secreted by tumor cells and stroma appear be the critical factors supporting and sustaining tumor colonization in bone. Co-targeting tumor and stroma with therapeutic agents has yielded promising results both in pre-clinical models of prostate cancer and bony metastasis and in clinical trials of patients treated with a dual tumor and stroma targeting strategies. In conclusion, understanding and targeting the interaction of the tumor and its stromal microenvironmant may improve the prognosis, reduce the suffering and increase the survival of patients with advanced cancer metastasis.     

Proteins of the Hedgehog signaling pathway as therapeutic targets against cancer

The Hedgehog pathway plays a crucial role in growth and patterning during embryonic development and is involved in stem cell maintenance and proliferation in adult tissues. Mutations that increase the overall activity of the pathway are often associated with a higher incidence of cancers. This article focuses on the mutations, misfoldings and deregulations of the Hedgehog pathway proteins that have been reported to be involved in different tumors, and on small molecules targeting these proteins shown to slow down the growth of certain tumors in various animal models. We propose that proteomics could be a powerful tool to identify new targets of the Hedgehog pathway, enabling the discovery of effective and novel treatments for cancers.     

The other side of the coin: dissecting molecular mechanisms behind hereditary breast cancer in search of therapeutic opportunities

Over the last quarter century several genetic alterations have been implicated in hereditary breast cancer (HBC). Two papers recently published in the New England Journal of Medicine explored the mutation prevalence in breast cancer predisposition genes across a large population of affected and unaffected subjects. These analyses designated ATM, BARD1, BRCA1, BRCA2, CHEK2, PALB2, RAD51C and RAD51D as the core set of genes associated with a significantly increased risk of developing breast cancer. A deeper understanding of the biological role of these genes unearths an intricate mechanism involving DNA repair and cell cycle regulation. Exploiting these inherited alterations for targeted treatments, as is currently the case with PARP inhibitors, may provide additional therapeutic opportunities for HBC patients.     

HOX cluster-embedded lncRNAs and epithelial-mesenchymal transition in cancer: Molecular mechanisms and therapeutic opportunities

Although there has been substantial improvement in the treatment modalities, cancer remains the major cause of fatality worldwide. Metastasis, recurrence, and resistance to oncological therapies are the leading causes of cancer mortality. Epithelial-mesenchymal transition (EMT) is a complex biological process that allows cancer cells to undergo morphological transformation into a mesenchymal phenotype to acquire invasive potential. It encompasses reversible and dynamic ontogenesis by neoplastic cells during metastatic dissemination. Hence, understanding the molecular landscape of EMT is imperative to identify a reliable clinical biomarker to combat metastatic spread. Accumulating evidence reveals the role of HOX (homeobox) cluster-embedded long non-coding RNAs (lncRNAs) in EMT and cancer metastasis. They play a crucial role in the induction of EMT, modulating diverse biological targets. The present review emphasizes the involvement of HOX cluster-embedded lncRNAs in EMT as a molecular sponge, chromatin remodeler, signaling regulator, and immune system modulator. Furthermore, the molecular mechanisms behind therapy resistance and the potential use of novel drugs targeting HOX cluster-embedded lncRNAs in the clinical management of distant metastasis will be discussed.     

Cell surface adhesion molecules and adhesion-initiated signaling: understanding of anoikis resistance mechanisms and therapeutic opportunities

Cells express various cell surface adhesion molecules (receptors) that not only mechanically serve as contacting sites between the cell and extracellular matrix (ECM) or adjacent cells, but also initiate intracellular signaling pathways modulating important cellular events including survival and proliferation. Normal cells undergo apoptosis when lacking ECM attachment. This type of cell death has been termed anoikis. Anoikis can be viewed as a normal process which ensures tissue homeostasis and failure to execute the anoikis program or resistance to anoikis could result in adherent cells surviving under suspension condition and proliferating at ectopic sites where the matrix proteins are different from those the cells originally contact. Resistance to anoikis is emerging as a hallmark of metastatic cancers which enables cancer cells to disseminate to distant organs through systemic circulation. In this review, we will discuss the molecular basis of adhesion-initiated signaling, the impact of loss of cell-ECM adhesion on normal cell survival, the role of cancer cell aggregate formation via intercellular adhesion under non-adherent condition, and mechanisms of anoikis resistance developed in metastatic cancer cells. Understanding of these aspects will provide opportunities to find new potential molecular targets, and therapeutic strategies based on these findings will likely prove to be more specific and effective.     

Eph receptors and their ligands: Promising molecular biomarkers and therapeutic targets in prostate cancer

Although at present, there is a high incidence of prostate cancer, particularly in the Western world, mortality from this disease is declining and occurs primarily only from clinically significant late stage tumors with a poor prognosis. A major current focus of this field is the identification of new biomarkers which can detect earlier, and more effectively, clinically significant tumors from those deemed “low risk”, as well as predict the prognostic course of a particular cancer. This strategy can in turn offer novel avenues for targeted therapies. The large family of Receptor Tyrosine Kinases, the Ephs, and their binding partners, the ephrins, has been implicated in many cancers of epithelial origin through stimulation of oncogenic transformation, tumor angiogenesis, and promotion of increased cell survival, invasion and migration. They also show promise as both biomarkers of diagnostic and prognostic value and as targeted therapies in cancer. This review will briefly discuss the complex roles and biological mechanisms of action of these receptors and ligands and, with regard to prostate cancer, highlight their potential as biomarkers for both diagnosis and prognosis, their application as imaging agents, and current approaches to assessing them as therapeutic targets. This review demonstrates the need for future studies into those particular family members that will prove helpful in understanding the biology and potential as targets for treatment of prostate cancer.     

Apoptosis evasion: the role of survival pathways in prostate cancer progression and therapeutic resistance

The ability of a tumor cell population to grow exponentially represents an imbalance between cellular proliferation and cellular attrition. There is an overwhelming body of evidence suggesting the ability of tumor cells to avoid programmed cellular attrition, or apoptosis, is a major molecular force driving the progression of human tumors. Apoptotic evasion represents one of the true hallmarks of cancer and appears to be a vital component in the immunogenic, chemotherapeutic, and radiotherapeutic resistance that characterizes the most aggressive of human cancers [Hanahan and Weinberg, 2000]. The challenges in the development of effective treatment modalities for advanced prostate cancer represent a classic paradigm of the functional significance of anti-apoptotic pathways in the development of therapeutic resistance.     

The HER family and cancer: emerging molecular mechanisms and therapeutic targets

The human epidermal growth factor receptor (HER) family of transmembrane tyrosine kinases regulates diverse cellular functions in response to extracellular ligands. The deregulation of HER signaling through gene amplification or mutation is seen in many human tumors and an abundance of experimental evidence supports the etiological role of these events in cancer pathogenesis. In addition, the fact that they are feasible targets for both antibody and small-molecule therapeutics has made them highly pursued targets for the development of rationally designed anticancer drugs. Several HER-targeting agents have entered clinical practice and this has led to novel discoveries regarding the mechanisms of resistance, which has defined a new generation of challenges for targeted cancer therapies. Here, we review recent advances in our understanding of HER signaling and targeting in cancer.     

The role,mechanism and potentially therapeutic application of microRNA-29 family in acute myeloid leukemia

Abnormal proliferation, apoptosis repression and differentiation blockage of hematopoietic stem/progenitor cells have been characterized to be the main reasons leading to acute myeloid leukemia (AML). Previous studies showed that miR-29a and miR-29b could function as tumor suppressors in leukemogenesis. However, a comprehensive investigation of the function and mechanism of miR-29 family in AML development and their potentiality in AML therapy still need to be elucidated. Herein, we reported that the family members, miR-29a, -29b and -29c, were commonly downregulated in peripheral blood mononuclear cells and bone marrow (BM) CD34+ cells derived from AML patients as compared with the healthy donors. Overexpression of each miR-29 member in THP1 and NB4 cells markedly inhibited cell proliferation and promoted cell apoptosis. AKT2 and CCND2 mRNAs were demonstrated to be targets of the miR-29 members, and the role of miR-29 family was attributed to the decrease of Akt2 and CCND2, two key signaling molecules. Significantly increased Akt2, CCND2 and c-Myc levels in the AML cases were detected, which were correlated with the decreased miR-29 expression in AML blasts. Furthermore, a feed-back loop comprising of c-Myc, miR-29 family and Akt2 were found in myeloid leukemogenesis. Reintroduction of each miR-29 member partially corrected abnormal cell proliferation and apoptosis repression and myeloid differentiation arrest in AML BM blasts. An intravenous injection of miR-29a, -29b and -29c in the AML model mice relieved leukemic symptoms significantly. Taken together, our finding revealed a pivotal role of miR-29 family in AML development and rescue of miR-29 family expression in AML patients could provide a new therapeutic strategy.     

Cancer stem cells in glioblastoma — molecular signaling and therapeutic targeting

Glioblastomas (GBMs) are highly lethal primary brain tumors. Despite current therapeutic advances in other solid cancers, the treatment of these malignant gliomas remains essentially palliative. GBMs are extremely resistant to conventional radiation and chemotherapies. We and others have demonstrated that a highly tumorigenic subpopulation of cancer cells called GBM stem cells (GSCs) promotes therapeutic resistance. We also found that GSCs stimulate tumor angiogenesis by expressing elevated levels of VEGF and contribute to tumor growth, which has been translated into a useful therapeutic strategy in the treatment of recurrent or progressive GBMs. Furthermore, stem cell-like cancer cells (cancer stem cells) have been shown to promote metastasis. Although GBMs rarely metastasize beyond the central nervous system, these highly infiltrative cancers often invade into normal brain tissues preventing surgical resection, and GSCs display an aggressive invasive phenotype. These studies suggest that targeting GSCs may effectively reduce tumor recurrence and significantly improve GBM treatment. Recent studies indicate that cancer stem cells share core signaling pathways with normal somatic or embryonic stem cells, but also display critical distinctions that provide important clues into useful therapeutic targets. In this review, we summarize the current understanding and advances in glioma stem cell research, and discuss potential targeting strategies for future development of anti-GSC therapies.     

Vitamin D signaling in immune-mediated disorders: Evolving insights and therapeutic opportunities

1,25(OH)(2)D(3), the active form of vitamin D, is a central player in calcium and bone metabolism. More recently, important immunomodulatory effects have been attributed to this hormone. The widespread presence of the vitamin D receptor (VDR) in the immune system and the expression of the enzymes responsible for the synthesis of the active 1,25(OH)(2)D(3) regulated by specific immune signals, even suggest a paracrine immunomodulatory role for 1,25(OH)(2)D(3). Additionally, the different molecular mechanisms used by 1,25(OH)(2)D(3) to exert its immunomodulatory effects prove of a broad action radius for this compound. Both, the effects of vitamin D deficiency and/or absence of the VDR as well as intervention with pharmacological doses of 1,25(OH)(2)D(3) or one of its less-calcemic analogs, affects immune system behavior in different animal models of immune-mediated disorders, such as type 1 diabetes. This review aims to summarize the data as they stand at the present time on the role of vitamin D in the pathogenesis of immune-mediated disorders, with special focus on type 1 diabetes, and on the therapeutic opportunities for vitamin D in the prevention and treatment of this autoimmune disease in mouse models and humans.     

大蒜阿霍烯抗胃癌的作用及分子机制*

目的: 探讨大蒜阿霍烯对胃癌细胞MGC-803的作用及相关分子机制。方法: 终浓度分别为0、1、5、25和125 μmol/L大蒜阿霍烯作用于细胞MGC-803 24 h、48 h和72 h,各设3复孔,MTS法检测细胞增殖活性,JC-1和Hoechst染色法观察线粒体膜电位和核型改变,LDH释放法检测细胞毒性,流式法分析细胞的凋亡和周期改变,RT-qPCR和Western blot检测P53、Caspase-3、RAS、ERK、BCL-2、AKT、mTOR、PI3K基因的表达,同时,取4周龄雄性BALB/C鼠随机分成5组,20只/组,腹股沟皮下接种胃癌细胞MGC-803,2 d后各组分别经皮下注射浓度为0 μmol/L、1 μmol/L、5 μmol/L、25 μmol/L、125 μmol/L的大蒜阿霍烯,0.1 ml/次,隔天注射一次,并于首次注射肿瘤细胞的第20日每组杀10只,取瘤组织,称重。记录剩余小鼠的存活期,观察大蒜阿霍烯对荷瘤小鼠胃癌生长及生存期的影响。结果: 大蒜阿霍烯可明显抑制MGC-803细胞增殖活性,诱导细胞凋亡(P＜0.01),显著上调P53、Caspase-3、BAX基因的转录和表达水平,抑制基因RAS、ERK1、BCL-2、AKT、mTOR和PI3K的表达(P＜0.01),显著抑制小鼠胃癌移植瘤生长,并延长荷瘤小鼠存活期(P＜0.01)。结论: 大蒜阿霍烯对胃癌有治疗作用,可通过调节PI3K-AKT-mTOR、RAS-RAF-MEK-ERK信号通路而抑制胃癌细胞增殖,诱导细胞凋亡。     

Metastatic breast cancer: mechanisms and opportunities for cytology

Despite significant advances in diagnosis, surgical techniques, general patient care, and local and systemic adjuvant therapies, metastatic disease remains the most critical condition limiting the survival of patients with breast cancer. Therefore, the development of effective treatment against late‐arising metastasis has become the centre of clinical attention and is one of the current challenges in cancer research. A deeper understanding of the metastatic cascade is fundamental, and the need for repetitive tumour assessments for the evaluation of tumour evolution is a relatively new practice in routine medical care. As such, fine needle aspiration cytology (FNAC) is ideally placed to monitor biological changes in metastasis that may affect treatment and response. As FNAC is a minimally invasive method, it can be performed repeatedly with relatively little trauma, and selective ancillary tests can be applied to FNAC specimens, including for tumour whose primary nature is known. Herein, we review how the linear and parallel models explain metastatic dissemination, thus influencing therapeutic and clinical decisions, and how cytology, together with immunocytochemistry and molecular analysis, can be a tool for routine clinical practice and clinical trials aimed at metastatic disease with a special emphasis on breast cancer.