Evaluating Temsirolimus Activity in Multiple Tumors: A Review of Clinical Trials

Cervical cancer therapies: current challenges and future perspectives

Cervical cancer is the fourth most common female cancer worldwide and results in over 300 000 deaths globally. The causative agent of cervical cancer is persistent infection with high-risk subtypes of the human papillomavirus and the E5, E6 and E7 viral oncoproteins cooperate with host factors to induce and maintain the malignant phenotype. Cervical cancer is a largely preventable disease and early-stage detection is associated with significantly improved survival rates. Indeed, in high-income countries with established vaccination and screening programs it is a rare disease. However, the disease is a killer for women in low- and middle-income countries who, due to limited resources, often present with advanced and untreatable disease. Treatment options include surgical interventions, chemotherapy and/or radiotherapy either alone or in combination. This review describes the initiation and progression of cervical cancer and discusses in depth the advantages and challenges faced by current cervical cancer therapies, followed by a discussion of promising and efficacious new therapies to treat cervical cancer including immunotherapies, targeted therapies, combination therapies, and genetic treatment approaches.

The Role of mTOR Inhibitors in Hematologic Disease: From Bench to Bedside

The mTOR pathway plays a central role in many cellular processes, such as cellular growth, protein synthesis, glucose, and lipid metabolism. Aberrant regulation of mTOR is a hallmark of many cancers, including hematological malignancies. mTOR inhibitors, such as Rapamycin and Rapamycin analogs (Rapalogs), have become a promising class of agents to treat malignant blood diseases-either alone or in combination with other treatment regimens. This review highlights experimental evidence underlying the molecular mechanisms of mTOR inhibitors and summarizes their evolving role in the treatment of hematologic disease, including leukemia, lymphoma, myeloma, immune hemocytopenia, and graft-versus-host disease (GVHD). Based on data presented in this review, we believe that mTOR inhibitors are becoming a trusted therapeutic in the clinical hematologist's toolbelt and should be considered more routinely in combination therapy for the management of hematologic disease.

The therapeutic potential of mTOR inhibitors in breast cancer

Rapamycin and modified rapamycins (rapalogs) have been used to prevent allograft rejection after organ transplant for over 15 years. The mechanistic target of rapamycin (mTOR) has been determined to be a key component of the mTORC1 complex which consists of the serine/threonine kinase TOR and at least five other proteins which are involved in regulating its activity. Some of the best characterized substrates of mTORC1 are proteins which are key kinases involved in the regulation of cell growth (e.g., p70S6K) and protein translation (e.g., 4E-BP1). These proteins may in some cases serve as indicators to sensitivity to rapamycin-related therapies. Dysregulation of mTORC1 activity frequently occurs due to mutations at, or amplifications of, upstream growth factor receptors (e.g., human epidermal growth factor receptor-2, HER2) as well as kinases (e.g., PI3K) and phosphatases (e.g., PTEN) critical in the regulation of cell growth. More recently, it has been shown that certain rapalogs may enhance the effectiveness of hormonal-based therapies for breast cancer patients who have become resistant to endocrine therapy. The combined treatment of certain rapalogs (e.g., everolimus) and aromatase inhibitors (e.g., exemestane) has been approved by the United States Food and Drug Administration (US FDA) and other drug regulatory agencies to treat estrogen receptor positive (ER+) breast cancer patients who have become resistant to hormonal-based therapies and have progressed. This review will summarize recent basic and clinical research in the area and evaluate potential novel therapeutic approaches.

Distinct signaling mechanisms of mTORC1 and mTORC2 in glioblastoma multiforme: a tale of two complexes

Mechanistic target of rapamycin (mTOR) is a serine-threonine kinase that functions via two multiprotein complexes, namely mTORC1 and mTORC2, each characterized by different binding partners that confer separate functions. mTORC1 function is tightly regulated by PI3-K/Akt and is sensitive to rapamycin. mTORC2 is sensitive to growth factors, not nutrients, and is associated with rapamycin-insensitivity. mTORC1 regulates protein synthesis and cell growth through downstream molecules: 4E-BP1 (also called EIF4E-BP1) and S6K. Also, mTORC2 is thought to modulate growth factor signaling by phosphorylating the C-terminal hydrophobic motif of some AGC kinases such as Akt and SGK. Recent evidence has suggested that mTORC2 may play an important role in maintenance of normal as well as cancer cells by virtue of its association with ribosomes, which may be involved in metabolic regulation of the cell. Rapamycin (sirolimus) and its analogs known as rapalogues, such as RAD001 (everolimus) and CCI-779 (temsirolimus), suppress mTOR activity through an allosteric mechanism that acts at a distance from the ATP-catalytic binding site, and are considered incomplete inhibitors. Moreover, these compounds suppress mTORC1-mediated S6K activation, thereby blocking a negative feedback loop, leading to activation of mitogenic pathways promoting cell survival and growth. Consequently, mTOR is a suitable target of therapy in cancer treatments. However, neither of these complexes is fully inhibited by the allosteric inhibitor rapamycin or its analogs. In recent years, new pharmacologic agents have been developed which can inhibit these complexes via ATP-binding mechanism, or dual inhibition of the canonical PI3-K/Akt/mTOR signaling pathway. These compounds include WYE-354, KU-003679, PI-103, Torin1, and Torin2, which can target both complexes or serve as a dual inhibitor for PI3-K/mTOR. This investigation describes the mechanism of action of pharmacological agents that effectively target mTORC1 and mTORC2 resulting in suppression of growth, proliferation, and migration of tumor and cancer stem cells.

Vascular tumors have increased p70 S6-kinase activation and are inhibited by topical rapamycin

Vascular tumors are endothelial cell neoplasms whose cellular and molecular mechanisms, leading to tumor formation, are poorly understood, and current therapies have limited efficacy with significant side effects. We have investigated mechanistic (mammalian) target of rapamycin (mTOR) signaling in benign and malignant vascular tumors, and the effects of mTOR kinase inhibitor as a potential therapy for these lesions. Human vascular tumors (infantile hemangioma and angiosarcoma) were analyzed by immunohistochemical stains and western blot for the phosphorylation of p70 S6-kinase (S6K) and S6 ribosomal protein (S6), which are activated downstream of mTOR complex-1 (mTORC1). To assess the function of S6K, tumor cells with genetic knockdown of S6K were analyzed for cell proliferation and migration. The effects of topical rapamycin, an mTOR inhibitor, on mTORC1 and mTOR complex-2 (mTORC2) activities, as well as on tumor growth and migration, were determined. Vascular tumors showed increased activation of S6K and S6. Genetic knockdown of S6K resulted in reduced tumor cell proliferation and migration. Rapamycin fully inhibited mTORC1 and partially inhibited mTORC2 activities, including the phosphorylation of Akt (serine 473) and PKCα, in vascular tumor cells. Rapamycin significantly reduced vascular tumor growth in vitro and in vivo. As a potential localized therapy for cutaneous vascular tumors, topically applied rapamycin effectively reduced tumor growth with limited systemic drug absorption. These findings reveal the importance of mTOR signaling pathways in benign and malignant vascular tumors. The mTOR pathway is an important therapeutic target in vascular tumors, and topical mTOR inhibitors may provide an alternative and well-tolerated therapy for the treatment of cutaneous vascular lesions.

Hypoxia regulates the sperm associated antigen 4 (SPAG4) via HIF, which is expressed in renal clear cell carcinoma and promotes migration and invasion in vitro

Hypoxia leads to the upregulation of a variety of genes mediated largely via the hypoxia inducible transcription factor (HIF). Prominent HIF-regulated target genes such as the vascular endothelial growth factor (VEGF), the glucose transporter 1 (Glut-1), or erythropoietin (EPO) help to assure survival of cells and organisms in a low oxygenated environment. Here, we are the first to report the hypoxic regulation of the sperm associated antigen 4 (SPAG4). SPAG4 is a member of the cancer testis (CT) gene family and to date little is known about its physiological function or its involvement in tumor biology. A number of CT family candidate genes are therefore currently being investigated as potential cancer markers, due to their predominant testicular expression pattern. We analyzed RNA and protein expression by RNAse protection assay, immunofluorescent as well as immunohistological stainings. To evaluate the influence of SPAG4 on migration and invasion capabilities, siRNA knockdown as well as transient overexpression was performed prior to scratch or invasion assay analysis. The hypoxic regulation of SPAG4 is clearly mediated in a HIF-1 and VHL dependent manner. We furthermore show upregulation of SPAG4 expression in human renal clear cell carcinoma (RCC) and co-localization within the nucleolus in physiological human testis tissue. SPAG4 knockdown reduces the invasion capability of RCC cells in vitro and overexpression leads to enhancement of tumor cell migration. Together, SPAG4 could possibly play a role in the invasion capability and growth of renal tumors and could represent an interesting target for clinical intervention.

Phase II trial of temsirolimus alone and in combination with irinotecan for KRAS mutant metastatic colorectal cancer: outcome and results of KRAS mutational analysis in plasma

BACKGROUND

Patients with chemotherapy refractory metastatic colorectal cancer and KRAS mutations have no effective treatment option. The present study evaluated the efficacy of temsirolimus in chemotherapy refractory mCRC with KRAS mutations. Furthermore, we wanted to investigate if resistance to temsirolimus could be reversed by the addition of irinotecan. Finally, we analyzed pre-treatment blood samples for KRAS mutations to investigate the association between quantitative measures of KRAS mutated alleles and clinical outcome.

MATERIAL AND METHODS

Patients received weekly temsirolimus 25 mg until progression. Thereafter patients were treated with combination therapy comprising biweekly irinotecan 180 mg/m(2) and weekly temsirolimus. A polymerase chain reaction method was used to quantify the KRAS mutated alleles in plasma (pKRAS).

RESULTS

Sixty-four patients were included. Treatment was well tolerated. Thirty-eight percent achieved stable disease on monotherapy and 63% on combination therapy. Four and eight patients had a minimal response, respectively. Median overall survival was 160 days. Median time to progression was 45 and 84 days, respectively. The concordance between KRAS status in tumor and plasma was 82%. All patients with tumor reduction had low levels of pKRAS. Patients with high pKRAS had a 77% risk of early progression on monotherapy compared to 43% in patients with lower levels. Multivariate survival analysis confirmed that pKRAS was a strong prognostic factor.

CONCLUSION

Temsirolimus has limited efficacy in chemotherapy resistant KRAS mutant disease, but plasma KRAS quantification is a strong predictor of outcome.

Deconstructing mTOR complexes in regulation of Glioblastoma Multiforme and its stem cells

Atypical serine-threonine kinase, mTOR (mechanistic target of Rapamycin; originally coined "mammalian TOR"), exists in two distinct multi-protein complexes termed mTOR complex 1 (mTORC1) and 2 (mTORC2), that senses and integrates a variety of environmental signals to control organism growth and homeostasis via non-overlapping signaling pathways. mTOR belongs to the phosphoinositide 3-kinase (PI3-K)-related kinase family, and an aberrant activation of mTORC1 is a potential contributing factor in uncontrolled cell growth, proliferation, and survival of tumor cells via specific effects on cap-dependent translation initiation, as well as in a more sustained manner via advancing ribosome biogenesis. It is thereby shown to be deregulated in numerous pathological conditions including cancer, obesity, type 2 diabetes, and neurodegeneration. Notably, mTOR itself, or through its substrates, regulates stem cell differentiation and maintenance of plueropotency. mTORC2 has been linked to cytoskeletal reorganization and cell survival through Akt, and is crucial to many divergent physiological functions, which may include stem cell regulation.

Activation of lysosomal function in the course of autophagy via mTORC1 suppression and autophagosome-lysosome fusion

Lysosome is a key subcellular organelle in the execution of the autophagic process and at present little is known whether lysosomal function is controlled in the process of autophagy. In this study, we first found that suppression of mammalian target of rapamycin (mTOR) activity by starvation or two mTOR catalytic inhibitors (PP242 and Torin1), but not by an allosteric inhibitor (rapamycin), leads to activation of lysosomal function. Second, we provided evidence that activation of lysosomal function is associated with the suppression of mTOR complex 1 (mTORC1), but not mTORC2, and the mTORC1 localization to lysosomes is not directly correlated to its regulatory role in lysosomal function. Third, we examined the involvement of transcription factor EB (TFEB) and demonstrated that TFEB activation following mTORC1 suppression is necessary but not sufficient for lysosomal activation. Finally, Atg5 or Atg7 deletion or blockage of the autophagosome-lysosome fusion process effectively diminished lysosomal activation, suggesting that lysosomal activation occurring in the course of autophagy is dependent on autophagosome-lysosome fusion. Taken together, this study demonstrates that in the course of autophagy, lysosomal function is upregulated via a dual mechanism involving mTORC1 suppression and autophagosome-lysosome fusion.

Modulating autophagy: a strategy for cancer therapy

Autophagy is a process in which long-lived proteins, damaged cell organelles, and other cellular particles are sequestered and degraded. This process is important for maintaining the cellular microenvironment when the cell is under stress. Many studies have shown that autophagy plays a complex role in human diseases, especially in cancer, where it is known to have paradoxical effects. Namely, autophagy provides the energy for metabolism and tumor growth and leads to cell death that promotes tumor suppression. The link between autophagy and cancer is also evident in that some of the genes that regulate Carcinogenesis, oncogenes and tumor suppressor genes, participate in or impact the autophagy process. Therefore, modulating autophagy will be a valuable topic for cancer therapy. Many studies have shown that autophagy can inhibit the tumor growth when autophagy modulators are combined with radiotherapy and/or chemotherapy. These findings suggest that autophagy may be a potent target for cancer therapy.

PTPN11-associated mutations in the heart: has LEOPARD changed Its RASpots?

In this review, we focus on elucidating the cardiac function of germline mutations in the PTPN11 gene, encoding the Src homology-2 (SH2) domain-containing protein tyrosine phosphatase SHP2. PTPN11 mutations cause LEOPARD syndrome (LS) and Noonan syndrome (NS), two disorders that are part of a newly classified family of autosomal dominant syndromes termed "RASopathies," which are caused by germline mutations in components of the RAS/RAF/MEK/ERK mitogen activating protein kinase pathway. LS and NS mutants have opposing biochemical properties, and yet, in patients, these mutations produce similar cardiac abnormalities. Precisely how LS and NS mutations lead to such similar disease etiology remains largely unknown. Recent complementary in vitro, ex vivo, and in vivo analyses reveal new insights into the functions of SHP2 in normal and pathological cardiac development. These findings also reveal the need for individualized therapeutic approaches in the treatment of patients with LS and NS and, more broadly, patients with the other "RASopathy" gene mutations as well.

Incidence and management of mTOR inhibitor-associated pneumonitis in patients with metastatic renal cell carcinoma

The administration of mammalian target of rapamycin (mTOR) inhibitors can give rise to a potentially life-threatening adverse event, often referred to as 'non-infectious pneumonitis' (NIP), which is characterized by non-infectious, non-malignant, and non-specific inflammatory infiltrates. Patients usually present with cough and/or dyspnoea. We provide a brief description of the mechanism of action of mTOR inhibitors and their overall safety in patients with metastatic renal cell carcinoma (mRCC) and review the literature on mTOR inhibitor-associated NIP in patients with solid tumours. The review was used to derive questions on the diagnosis, management, and monitoring of mRCC patients with NIP, and to develop a decision tree for use in routine clinical practise. A key recommendation was the subdivision of grade 2 NIP into grades 2a and 2b, where grade 2a is closer to grade 1 and grade 2b to grade 3. This subdivision is important because it takes into account the nature and severity of clinical symptoms potentially related to NIP, either the onset of new symptoms or the worsening of existing symptoms, and thus determines the type and frequency of follow-up. It also helps to identify a subgroup of patients in whom treatment, if effective, may be continued without dose adjustment.

Cardiotoxicity of molecularly targeted agents

Cardiac toxicity of molecularly targeted cancer agents is increasingly recognized as a significant side effect of chemotherapy. These new potent therapies may not only affect the survival of cancer cells, but have the potential to adversely impact normal cardiac and vascular function. Unraveling the mechanisms by which these therapies affect the heart and vasculature is crucial for improving drug design and finding alternative therapies to protect patients predisposed to cardiovascular disease. In this review, we summarize the classification and side effects of currently approved molecularly targeted chemotherapeutics.

Exploiting cancer cell vulnerabilities to develop a combination therapy for ras-driven tumors

Ras-driven tumors are often refractory to conventional therapies. Here we identify a promising targeted therapeutic strategy for two Ras-driven cancers: Nf1-deficient malignancies and Kras/p53 mutant lung cancer. We show that agents that enhance proteotoxic stress, including the HSP90 inhibitor IPI-504, induce tumor regression in aggressive mouse models, but only when combined with rapamycin. These agents synergize by promoting irresolvable ER stress, resulting in catastrophic ER and mitochondrial damage. This process is fueled by oxidative stress, which is caused by IPI-504-dependent production of reactive oxygen species, and the rapamycin-dependent suppression of glutathione, an important endogenous antioxidant. Notably, the mechanism by which these agents cooperate reveals a therapeutic paradigm that can be expanded to develop additional combinations.

Targeting cap-dependent translation blocks converging survival signals by AKT and PIM kinases in lymphoma

New anticancer drugs that target oncogenic signaling molecules have greatly improved the treatment of certain cancers. However, resistance to targeted therapeutics is a major clinical problem and the redundancy of oncogenic signaling pathways provides back-up mechanisms that allow cancer cells to escape. For example, the AKT and PIM kinases produce parallel oncogenic signals and share many molecular targets, including activators of cap-dependent translation. Here, we show that PIM kinase expression can affect the clinical outcome of lymphoma chemotherapy. We observe the same in animal lymphoma models. Whereas chemoresistance caused by AKT is readily reversed with rapamycin, PIM-mediated resistance is refractory to mTORC1 inhibition. However, both PIM- and AKT-expressing lymphomas depend on cap-dependent translation, and genetic or pharmacological blockade of the translation initiation complex is highly effective against these tumors. The therapeutic effect of blocking cap-dependent translation is mediated, at least in part, by decreased production of short-lived oncoproteins including c-MYC, Cyclin D1, MCL1, and the PIM1/2 kinases themselves. Hence, targeting the convergence of oncogenic survival signals on translation initiation is an effective alternative to combinations of kinase inhibitors.

Sirolimus demonstrates activity in the primary therapy of acute graft-versus-host disease without systemic glucocorticoids

BACKGROUND

Advances in acute graft-versus-host disease therapy are needed.

DESIGN AND METHODS

We examined the efficacy of sirolimus as primary therapy for acute graft-versus-host disease in 32 patients.

RESULTS

Acute graft-versus-host disease involved the skin in 53% of cases, gastrointestinal tract in 66%, liver in 16%. The syndrome was overall grade 1 in 12% cases, grade 2 in 75%, and grade 3 in 13%. Sirolimus was targeted to achieve serum trough levels of 5-14 ng/mL. Sixteen (50%) patients achieved sustained, complete resolution of acute graft-versus-host disease with sirolimus alone. In contrast, 19 of 32 (59%) matched historical controls treated with standard 1 mg/kg steroids achieved complete response (P=0.47). With median follow-up time for surviving patients of 16 (range 6-26) months, one year overall survival was 56% (95% CI 38-74%). The cumulative incidence of relapse at one year was 37% (95% CI 23-60%), and mortality in remission was 20% (95% CI 10-42%). The cumulative incidence of chronic graft-versus-host disease was 55% (95% CI 39-79%). Thrombotic microangiopathy occurred in 3 cases (grade 1 n=1; grade 2 n=2), and responded to dose reduction of calcineurin inhibitor.

CONCLUSIONS

In this retrospective series, sirolimus demonstrates activity comparable to that of high-dose glucocorticoids in the primary therapy of acute graft-versus-host disease. Confirmation of this activity requires prospective clinical trials.

Widespread deregulation of phosphorylation-based signaling pathways in multiple myeloma cells: opportunities for therapeutic intervention

Multiple myeloma (MM) is a neoplasm of plasma cell origin that is largely confined to the bone marrow (BM). Chromosomal translocations and other genetic events are known to contribute to deregulation of signaling pathways that lead to transformation of plasma cells and progression to malignancy. However, the tumor stroma may also provide trophic support and enhance resistance to therapy. Phosphorylation of proteins on tyrosine, serine and threonine residues plays a pivotal role in cell growth and survival. Therefore, knowing the status of phosphorylation-based signaling pathways in cells may provide key insights into how cell growth and survival is promoted in tumor cells. To provide a more comprehensive molecular analysis of signaling disruptions in MM, we conducted a kinome profile comparison of normal plasma cells and MM plasma cells as well as their surrounding cells from normal BM and diseased BM. Integrated pathway analysis of the profiles obtained reveals deregulation of multiple signaling pathways in MM cells but also in surrounding bone marrow blood cells compared to their normal counterparts. The deregulated kinase activities identified herein, which include the mTOR (mammalian target of rapamycin)/p70S6K and ERK1/2 (extracellular signal-regulated kinases 1 and 2) pathways, are potential novel molecular targets in this lethal disease.

Selecting multimodal therapy for rhabdomyosarcoma

Rhabdomyosarcoma is a typical tumor of childhood, characterized by a high grade of malignancy, local invasiveness and a marked propensity to metastasize, but also a generally good response to chemotherapy and radiotherapy. Multimodal therapy is essential to cure rhabdomyosarcoma patients, but different uses of surgery, radiotherapy and chemotherapy, and their intensity, need to be selected and modulated to different patient risk groups. This article attempts to give an account of the current treatment options, the open and debated issues and the potential novel strategies for the near future.

Rapamycin inhibits anal carcinogenesis in two preclinical animal models

The incidence of anal cancer is increasing especially among HIV-infected persons in the HAART era. Treatment of this cancer is based upon traditional chemoradiotherapeutic approaches, which are associated with high morbidity and of limited effectiveness for patients with high-grade disease. The mammalian target of rapamycin (mTOR) pathway has been implicated in several human cancers, and is being investigated as a potential therapeutic target. In archival human anal cancers, we observed mTOR pathway activation. To assess response of anal cancer to mTOR inhibition, we utilized two newly developed mouse models, one in which anal cancers are induced to arise in HPV16 transgenic mice and the second a human anal cancer xenograft model. Using the transgenic mouse model, we assessed the preventative effect of rapamycin on neoplastic disease. We saw significant changes in the overall incidence of tumors, and tumor growth rate was also reduced. Using both the transgenic mouse and human anal xenograft mouse models, we studied the therapeutic effect of rapamycin on preexisting anal cancer. Rapamycin was found to significantly slow, if not stop, the growth of both mouse and human anal cancers. As has been seen in other cancers, rapamycin treatment led to an activation of the MAPK pathway. These results provide us cause to pursue further the evaluation of rapamycin as a therapeutic agent in the control of anal cancer.

Rapamycin reverses hypertrophic cardiomyopathy in a mouse model of LEOPARD syndrome-associated PTPN11 mutation

LEOPARD syndrome (LS) is an autosomal dominant "RASopathy" that manifests with congenital heart disease. Nearly all cases of LS are caused by catalytically inactivating mutations in the protein tyrosine phosphatase (PTP), non-receptor type 11 (PTPN11) gene that encodes the SH2 domain-containing PTP-2 (SHP2). RASopathies typically affect components of the RAS/MAPK pathway, yet it remains unclear how PTPN11 mutations alter cellular signaling to produce LS phenotypes. We therefore generated knockin mice harboring the Ptpn11 mutation Y279C, one of the most common LS alleles. Ptpn11(Y279C/+) (LS/+) mice recapitulated the human disorder, with short stature, craniofacial dysmorphia, and morphologic, histologic, echocardiographic, and molecular evidence of hypertrophic cardiomyopathy (HCM). Heart and/or cardiomyocyte lysates from LS/+ mice showed enhanced binding of Shp2 to Irs1, decreased Shp2 catalytic activity, and abrogated agonist-evoked Erk/Mapk signaling. LS/+ mice also exhibited increased basal and agonist-induced Akt and mTor activity. The cardiac defects in LS/+ mice were completely reversed by treatment with rapamycin, an inhibitor of mTOR. Our results demonstrate that LS mutations have dominant-negative effects in vivo, identify enhanced mTOR activity as critical for causing LS-associated HCM, and suggest that TOR inhibitors be considered for treatment of HCM in LS patients.

Intranuclear function for protein phosphatase 2A: Pph21 and Pph22 are required for rapamycin-induced GATA factor binding to the DAL5 promoter in yeast

Protein phosphatase 2A (PP2A), a central Tor pathway phosphatase consisting of a catalytic subunit (Pph21 or Pph22), a scaffold subunit (Tpd3), and one of two regulatory subunits (Cdc55 or Rts1), has been repeatedly shown to play important roles in cytoplasmically localized signal transduction activities. In contrast, its involvement in intranuclear control of mRNA production has heretofore not been reported. Here, we demonstrate for the first time that binding of the nitrogen catabolite repression-responsive GATA transcription activators (Gln3 and Gat1) to the DAL5 promoter and DAL5 expression require Pph21/22-Tpd3-Cdc55/Rts1 in rapamycin-treated glutamine-grown cells. This conclusion is supported by the following observations. (i) Rapamycin-induced DAL5 expression along with Gln3 and Gat1 binding to the DAL5 promoter fails to occur in pph21Δ pph22Δ, tpd3Δ, and cdc55Δ rts1Δ mutants. (ii) The Pph21/22 requirement persists even when Gat1 and Gln3 are rendered constitutively nuclear, thus dissociating the intranuclear requirement of PP2A from its partial requirement for rapamycin-induced nuclear Gat1 localization. (iii) Pph21-Myc(13) (Ppp21 tagged at the C terminus with 13 copies of the Myc epitope) weakly associates with the DAL5 promoter in a Gat1-dependent manner, whereas a similar Pph22-Myc(13) association requires both Gln3 and Gat1. Finally, we demonstrate that a pph21Δ pph22Δ double mutant is epistatic to ure2Δ for nuclear Gat1 localization in untreated glutamine-grown cells, whereas for Gln3, just the opposite occurs: i.e., ure2Δ is epistatic to pph21Δ pph22Δ. This final observation adds additional support to our previous conclusion that the Gln3 and Gat1 GATA factor localizations are predominantly controlled by different regulatory pathways.

Temsirolimus for metastatic desmoplastic small round cell tumor

Desmoplastic small round cell tumor (DSRCT) is a rare and aggressive neoplasm that mostly occurs in young males. No curative treatment options currently exist for this type of tumor and long-term survival remains poor. In vitro rapamycin induces apoptotic death of JN-DSRCT-1 cells, a possible model for desmoplastic small round cell tumors in which the EWS gene is fused to the WT1 gene. We therefore demonstrate the prolonged activity of temsirolimus, an mTOR-inhibitor, in a patient with DSRCT.

Development of target-specific treatments in multiple myeloma

In the last decade, the novel agents lenalidomide, bortezomib, and thalidomide have dramatically improved outcomes for patients with multiple myeloma (MM). A number of new therapies with precise targets involved in MM cell growth and replication are now in development and have the potential for further improvements. Second-generation proteasome inhibitors and thalidomide derivatives may offer increased efficacy and safety. Investigational therapies with rationally selected targets in MM include inhibitors of histone deacetylase, heat shock protein 90, mammalian target of rapamycin, BCL2, Akt, mitogen-activated protein kinase, and telomerase. In addition, monoclonal antibodies directed against several targets have been developed and many are showing promise in initial clinical trials in MM. Interest in the ancient remedy of arsenic trioxide has been revived because of its proapoptotic effects on mitochondria, despite its established toxicities. In general, combination regimens are proving the most efficacious, which is to be expected given the multiple overlapping pathways responsible for MM growth and progression.

mTOR signaling is involved in indomethacin and nimesulide suppression of colorectal cancer cell growth via a COX-2 independent pathway

BACKGROUND

Inhibition of mammalian target of rapamycin (mTOR) represents an attractive target for anticancer therapy, but its role in suppression of colorectal cancer (CRC) cell growth by cyclooxygenase-2 (COX-2) inhibitors is unclear. Here, we analyzed the effect of indomethacin (Indo, a nonselective COX-2 inhibitor) and nimesulide (Nim, a selective COX-2 inhibitor) on mTOR signaling in CRC cells in vitro and in vivo to determine the dependence of this effect on COX-2.

METHODS

Human CRC cell lines with varying COX-2 expression levels were treated with Indo and Nim. Western blot test was performed to detect mTOR-related components (mTOR, p70s6 K, and 4EBP1), and cell viability, cell cycle, and apoptosis were assessed. HCT116 and SW1116 cells were injected into athymic nude mice to establish a CRC xenograft model. After treatment with Nim, tumor volume, mTOR signaling, and apoptosis were evaluated in this model. HT29 and SW1116 cells were also treated with Nim after transfection with COX-2-specific small interfering RNA (siRNA) to assess dependence of COX-2 on mTOR signaling under drug treatment.

RESULTS

Both Indo and Nim reduced mTOR signaling activity in CRC cells that differ in their COX-2 expression in vitro and in vivo. Additionally, Indo and Nim could reduce the mTOR signaling activity after COX-2 silencing in CRC cells.

CONCLUSIONS

mTOR signaling is involved in Indo- and Nim-mediated suppression of CRC growth via a COX-2 independent pathway. This study unveils a novel mechanism through which COX-2 inhibitors exerts their anticancer effects and further emphasizes targeting mTOR signaling in anticancer therapy.

Pharmacotherapy of neuroblastoma

IMPORTANCE OF THE FIELD

Neuroblastoma, a tumor of the sympathetic nervous system, is the most common extracranial solid tumor of early life. High risk disease in older children remains a therapeutic challenge, despite high-intensity therapy with correspondingly significant short- and long-term toxicities.

AREAS COVERED IN THIS REVIEW

We have reviewed therapy for neuroblastoma over the last three decades. This includes cytotoxic chemotherapy, immunotherapy, radionuclides, antiangiogenic compounds, and molecularly targeted agents. We provide a perspective on the incorporation of these drugs into therapy for neuroblastoma.

WHAT THE READER WILL GAIN

The reader will gain a better understanding of these novel agents and their targets in neuroblastoma. The reader will also gain insight into the need to define through sequential, carefully designed clinical trials, the roles and toxicities of these therapies, especially if the combination of targeted and conventional cytotoxic agents is used.

TAKE HOME MESSAGE

Advanced-stage neuroblastoma in older infants and children remains a disease that is difficult to cure. New, targeted agents may improve both the therapeutic index and the outcome, but are, for the most part, in early development and present a challenge for clinical trial design given both the rarity of this disease and its responsiveness (albeit incomplete) to currently used cytotoxic agents.

Methyl 2-cyano-3,11-dioxo-18-olean-1,12-dien-30-oate (CDODA-Me), a derivative of glycyrrhetinic acid, functions as a potent angiogenesis inhibitor

Methyl 2-cyano-3,11-dioxo-18-olean-1,12-dien-30-oate (CDODA-Me), a triterpenoid acid derived synthetically from glycyrrhetinic acid, has been characterized as a peroxisome proliferator-activated receptor γ agonist with a broad range of receptor-dependent and -independent anticancer activities. Although CDODA-Me decreases the expression of some angiogenic genes in cancer cells, the direct effects of this compound on angiogenesis have not been defined. In this study, we have extensively investigated the activities of CDODA-Me in multiple angiogenesis assays. Our results showed that this agent inhibited vascular endothelial growth factor (VEGF)-induced proliferation, migration, invasion, and lamellipodium and capillary-like structure formation of human umbilical endothelial cells (HUVECs) in a concentration-dependent manner. Moreover, CDODA-Me abrogated VEGF-induced sprouting of microvessels from rat aortic rings ex vivo and inhibited the generation of new vasculature in the Matrigel plugs in vivo, where CDODA-Me significantly decreased the number of infiltrating von Willebrand factor-positive endothelial cells. To understand the molecular basis of this antiangiogenic activity, we examined the signaling pathways in CDODA-Me-treated HUVECs. Our results showed that CDODA-Me significantly suppressed the activation of VEGF receptor 2 (VEGFR2) and interfered with the mammalian target of rapamycin (mTOR) signaling, including mTOR kinase and its downstream ribosomal S6 kinase (S6K), but had little effect on the activities of extracellular signal-regulated protein kinase and AKT. Taken together, CDODA-Me blocks several key steps of angiogenesis by inhibiting VEGF/VEGFR2 and mTOR/S6K signaling pathways, making the compound a promising agent for the treatment of cancer and angiogenesis-related pathologies.

PET in Brain Tumors

Evaluating gliomas, either at diagnosis or at recurrence, is among the historical indications of FDG positron emission tomography (PET) imaging. There is a clear relationship between the tumor grade, patient prognosis, and intensity of uptake. Yet the exact role of FDG PET imaging remains debated. PET and methionine labeled with the short-lived C11 also have been proposed, with the significant advantage of high tumor-to-cortex contrast and distinct bological properties that lead to specific indications. Clinical use of this tracer is hampered by the need for an on-site cyclotron, however. In recent years, the increased availability of fluorinated amino-acid analogs, in particular FET, has open the way to renewed scientific interest in the field of neuro-oncological PET and PET/CT. This article discusses FDG and alternative tracers for diagnosing and characterizing primary brain tumors, detecting their recurrences, helping to guide the radiation therapy, and for evaluating the response to treatments.

Dietary interventions to extend life span and health span based on calorie restriction

The societal impact of obesity, diabetes, and other metabolic disorders continues to rise despite increasing evidence of their negative long-term consequences on health span, longevity, and aging. Unfortunately, dietary management and exercise frequently fail as remedies, underscoring the need for the development of alternative interventions to successfully treat metabolic disorders and enhance life span and health span. Using calorie restriction (CR)-which is well known to improve both health and longevity in controlled studies-as their benchmark, gerontologists are coming closer to identifying dietary and pharmacological therapies that may be applicable to aging humans. This review covers some of the more promising interventions targeted to affect pathways implicated in the aging process as well as variations on classical CR that may be better suited to human adaptation.