Rapamycin induces apoptosis of JN-DSRCT-1 cells by increasing the Bax : Bcl-xL ratio through concurrent mechanisms dependent and independent of its mTOR inhibitory activity

Strategies for the Treatment of Desmoplastic Small Round Cell Tumor: A Case Series

Desmoplastic small round cell tumor (DSRCT) is a rare, aggressive pediatric sarcoma that has a poor prognosis despite a multimodal approach of surgical resection, chemotherapy, and radiation. Incidence is only approximately 0.2 cases per million, limiting clinical trials from which to derive a standard of treatment. Advancement instead relies on case reports and series. The Children's Hospital at Montefiore in the Bronx, New York, a tertiary care hospital associated with the Montefiore Einstein Comprehensive Cancer Center, has treated eight such patients in the last decade, resulting in one of the largest single-institution case series of DSRCT patients to date. Though these patients are demographically unusual for DSRCT, including two women and two with rare extra-abdominal tumors of the brain and bone, through treatment of these patients we have accrued experience regarding various treatment strategies in both primary and refractory DSRCT. We treat primary DSRCT with interval-compressed vincristine/doxorubicin/cyclophosphamide alternating with cycles of ifosfamide/etoposide and irinotecan/temozolomide/temsirolimus (ITT). This is the first descriptive series of this size describing the use of ITT in DSRCT. Treatment for refractory cases focuses on targeted therapies when available, emphasizing the personalization that DSRCT treatment requires.

Small round cell sarcomas

Undifferentiated small round cell sarcomas (SRCSs) of bone and soft tissue comprise a heterogeneous group of highly aggressive tumours associated with a poor prognosis, especially in metastatic disease. SRCS entities mainly occur in the third decade of life and can exhibit striking disparities regarding preferentially affected sex and tumour localization. SRCSs comprise new entities defined by specific genetic abnormalities, namely EWSR1-non-ETS fusions, CIC-rearrangements or BCOR genetic alterations, as well as EWSR1-ETS fusions in the prototypic SRCS Ewing sarcoma. These gene fusions mainly encode aberrant oncogenic transcription factors that massively rewire the transcriptome and epigenome of the as yet unknown cell or cells of origin. Additional mutations or copy number variants are rare at diagnosis and, depending on the tumour entity, may involve TP53, CDKN2A and others. Histologically, these lesions consist of small round cells expressing variable levels of CD99 and specific marker proteins, including cyclin B3, ETV4, WT1, NKX3-1 and aggrecan, depending on the entity. Besides locoregional treatment that should follow standard protocols for sarcoma management, (neo)adjuvant treatment is as yet ill-defined but generally follows that of Ewing sarcoma and is associated with adverse effects that might compromise quality of life. Emerging studies on the molecular mechanisms of SRCSs and the development of genetically engineered animal models hold promise for improvements in early detection, disease monitoring, treatment-related toxicity, overall survival and quality of life.

Desmoplastic Small Round Cell Tumor: A Review of Main Molecular Abnormalities and Emerging Therapy

Simple Summary

Desmoplastic small round cell tumor is a rare neoplasm with extremely aggressive behavior. Despite the multimodal treatment for newly diagnosed patients with chemotherapy, cytoreductive surgery and radiation, the cure rate is still low. For relapsed or progressive disease, there is limited data regarding second and third-line therapies. Novel agents have shown only modest activity. Recent molecular changes have been identified in this disease and this opens opportunities to be explored in future clinical trials.

Abstract

Desmoplastic small round cell tumor (DSRCT) is an extremely rare, aggressive sarcoma affecting adolescents and young adults with male predominance. Generally, it originates from the serosal surface of the abdominal cavity. The hallmark characteristic of DSRCT is the EWSR1–WT1 gene fusion. This translocation up-regulates the expression of PDGFRα, VEGF and other proteins related to tumor and vascular cell proliferation. Current management of DSRCT includes a combination of chemotherapy, radiation and aggressive cytoreductive surgery plus intra-peritoneal hyperthermic chemotherapy (HIPEC). Despite advances in multimodal therapy, outcomes remain poor since the majority of patients present disease recurrence and die within three years. The dismal survival makes DSRCT an orphan disease with an urgent need for new drugs. The treatment of advanced and recurrent disease with tyrosine kinase inhibitors, such as pazopanib, sunitinib, and mTOR inhibitors was evaluated by small trials. Recent studies using comprehensive molecular profiling of DSRCT identified potential therapeutic targets. In this review, we aim to describe the current studies conducted to better understand DSRCT biology and to explore the new therapeutic strategies under investigation in preclinical models and in early phase clinical trials.

Desmoplastic Small Round Cell Tumors: A review with focus on clinical management and therapeutic options

Desmoplastic Small Round Cell Tumors (DSRCTs) are an entity of rare, aggressive soft tissue sarcomas described by Gerald and Rosai in 1989. It predominantly affects male adolescents and young adults, with a peak incidence between an age of 20 and 30 years. Typically, DSRCT demonstrate as multiple small tumor nodules within the abdominal cave, retroperitoneum and pelvis. In more than 50% of the cases, the neoplasm presents metastatic at the timepoint of diagnosis. Histologically, DSRCTs have a characteristic morphology with sharply demarcated islands of uniform small round cells in abundant desmoplastic stroma organized in loose extracellular matrix. Immunohistochemistry reveals a polyphenotypic differentiation with co-expression of epithelial, myogenic, mesenchymal and neural markers. The morphology is highly variable and can hinder diagnosis. The most consistent molecular characteristic of DSRCT is the reciprocal t(11;22)(p13q12) translocation. This mutation leads to a formation of the EWSR1-WT1 fusion oncogene, which encodes for a chimeric protein with transcriptional regulatory activity and is regarded as driving source of the disease. To date, there is no standardized concept for clinical management, staging and treatment. Patients receive an aggressive multimodal therapeutic approach consisting of chemotherapy, radical surgical procedures, hyperthermic, intraperitoneal chemotherapy (HIPEC) and radiation. New targeted therapies are used in experimental settings as salvage therapy. So far, none of these therapies showed significant long-term success. This review gives an overview of diagnostic difficulties and pitfalls, discusses therapeutic strategies and highlights options for clinical management.

Photodynamic Therapy Using a Novel Phosphorus Tetraphenylporphyrin Induces an Anticancer Effect via Bax/Bcl-xL-related Mitochondrial Apoptosis in Biliary Cancer Cells

Photodynamic therapy (PDT) uses photosensitizer activation by light of a specific wavelength, and is a promising treatment for various cancers; however, the detailed mechanism of PDT remains unclear. Therefore, we investigated the anticancer effect of PDT using a novel phosphorus tetraphenylporphyrin (Ptpp) in combination with light emitting diodes (Ptpp-PDT) in the NOZ human biliary cancer cell line. Cell viability and apoptosis were examined by MTT assay, flow cytometry and TUNEL assay for 24 hr after Ptpp-PDT. MitoTracker and JC-1 were used as markers of mitochondrial localization and membrane potential. The levels of mitochondrial oxidative phosphorylation (OXPHOS) complexes, Bcl-2 family proteins, cytochrome c and cleaved caspase-3 were examined by western blotting and immunohistochemistry. The results revealed that Ptpp localized to mitochondria, and that Ptpp-PDT efficiently decreased cell viability in a dose- and time-dependent manner. JC-1 and OXPHOS complexes decreased, but apoptotic cells increased from 6 to 24 hr after Ptpp-PDT. A decrease in Bcl-xL and increases in Bax, cytochrome c and cleaved caspase-3 were also found from 6 to 24 hr after Ptpp-PDT. Based on these results, we conclude that Ptpp-PDT induces anticancer effects via the mitochondrial apoptotic pathway by altering the Bax/Bcl-xL ratio, and could be an effective treatment for human biliary cancer.

Rapamycin inhibits B-cell activating factor (BAFF)-stimulated cell proliferation and survival by suppressing Ca2+-CaMKII-dependent PTEN/Akt-Erk1/2 signaling pathway in normal and neoplastic B-lymphoid cells

B-cell activating factor (BAFF) is a crucial survival factor for B cells, and excess BAFF contributes to development of autoimmune diseases. Recent studies have shown that rapamycin can prevent BAFF-induced B-cell proliferation and survival, but the underlying mechanism remains to be elucidated. Here we found that rapamycin inhibited human soluble BAFF (hsBAFF)-stimulated cell proliferation by inducing G₁-cell cycle arrest, which was through downregulating the protein levels of CDK2, CDK4, CDK6, cyclin A, cyclin D1, and cyclin E. Rapamycin reduced hsBAFF-stimulated cell survival by downregulating the levels of anti-apoptotic proteins (Mcl-1, Bcl-2, Bcl-xL and survivin) and meanwhile upregulating the levels of pro-apoptotic proteins (BAK and BAX). The cytostatic and cytotoxic effects of rapamycin linked to its attenuation of hsBAFF-elevated intracellular free Ca²⁺ ([Ca²⁺]_i). In addition, rapamycin blocked hsBAFF-stimulated B-cell proliferation and survival by preventing hsBAFF from inactivating PTEN and activating the Akt-Erk1/2 pathway. Overexpression of wild type PTEN or ectopic expression of dominant negative Akt potentiated rapamycin's suppression of hsBAFF-induced Erk1/2 activation and proliferation/viability in Raji cells. Interestingly, PP242 (mTORC1/2 inhibitor) or Akt inhibitor X, like rapamycin (mTORC1 inhibitor), reduced the basal or hsBAFF-induced [Ca²⁺]_i elevations. Chelating [Ca²⁺]_i with BAPTA/AM, preventing [Ca²⁺]_i elevation using EGTA, 2-APB or verapamil, inhibiting CaMKII with KN93, or silencing CaMKII strengthened rapamycin's inhibitory effects. The results indicate that rapamycin inhibits BAFF-stimulated B-cell proliferation and survival by blunting mTORC1/2-mediated [Ca²⁺]_i elevations and suppressing Ca²⁺-CaMKII-dependent PTEN/Akt-Erk1/2 signaling pathway. Our finding underscores that rapamycin may be exploited for prevention of excessive BAFF-induced aggressive B-cell malignancies and autoimmune diseases.

Cinobufagin suppresses colorectal cancer angiogenesis by disrupting the endothelial mammalian target of rapamycin/hypoxia-inducible factor 1α axis

Inducing angiogenesis is a hallmark of cancers that sustains tumor growth and metastasis. Neovascularization is a surprisingly early event during the multistage progression of cancer. Cinobufagin, an important bufadienolide originating from Chan Su, has been clinically used to treat cancer in China since the Tang dynasty. Here, we show that cinobufagin suppresses colorectal cancer (CRC) growth in vivo by downregulating angiogenesis. The hierarchized neovasculature is significantly decreased and the vascular network formation is disrupted in HUVEC by cinobufagin in a dose‐dependent way. Endothelial apoptosis is observed by inducing reactive oxygen species (ROS) accumulation and mitochondrial dysfunction which can be neutralized by N‐acetyl‐l‐cysteine (NAC). Expression of hypoxia‐inducible factor 1α (HIF‐1α) is reduced and phosphorylation of mTOR at Ser2481 and Akt at Ser473 is downregulated in HUVEC. Endothelial apoptosis is triggered by cinobufagin by stimulation of Bax and cascade activation of caspase 9 and caspase 3. Increased endothelial apoptosis rate and alterations in the HIF‐1α/mTOR pathway are recapitulated in tumor‐bearing mice in vivo. Further, the anti‐angiogenesis function of cinobufagin is consolidated based on its pro‐apoptotic effects on an EOMA‐derived hemangioendothelioma model. In conclusion, cinobufagin suppresses tumor neovascularization by disrupting the endothelial mTOR/HIF‐1α pathway to trigger ROS‐mediated vascular endothelial cell apoptosis. Cinobufagin is a promising natural anti‐angiogenetic drug that has clinical translation potential and practical application value.

Potential use of melatonin in skin cancer treatment: A review of current biological evidence

Skin cancer, particularly melanoma, is a leading cause of death worldwide. The therapeutic methods for this malignancy are not effective, and due to the side effects of these treatments, applying an appropriate alternative or complementary treatment is important. According to available data, melatonin as the main product of the pineal gland has oncostatic and antitumoral properties. Also, melatonin acts as an anti-inflammatory and reactive oxygen species inducer agent which suppresses the growth of tumors. It also has apoptosis induction characteristics through regulating signaling pathways, including heat shock protein 70, nuclear factor-erythroid 2 p45-related factor 2 and others. Thus, adding melatonin to chemo- and radiotherapy may have synergistic therapeutic effects and increase the survival time in patients with skin cancer. Few clinical studies have evaluated the efficacy of melatonin in skin cancer. Based on the related mechanisms, this review discusses about how melatonin may improve outcomes in skin cancer patients.

Desmoplastic Small Round Blue Cell Tumor: A Review of Treatment and Potential Therapeutic Genomic Alterations

Desmoplastic small round blue cell tumors (DSRCTs) originate from a cell with multilineage potential. A molecular hallmark of DSRCT is the EWS-WT1 reciprocal translocation. Ewing sarcoma and DSRCT are treated similarly due to similar oncogene activation pathways, and DSRCT has been represented in very limited numbers in sarcoma studies. Despite aggressive therapy, median survival ranges from 17 to 25 months, and 5-year survival rates remain around 15%, with higher survival reported among those undergoing removal of at least 90% of tumor in the absence of extraperitoneal metastasis. Almost 100% of these tumors contain t(11;22) (p13;q12) translocation, and it is likely that EWS-WT1 functions as a transcription factor possibly through WT1 targets. While there is no standard protocol for this aggressive disease, treatment usually includes the neoadjuvant HD P6 regimen (high-dose cyclophosphamide, doxorubicin, and vincristine (HD-CAV) alternating with ifosfamide and etoposide (IE) chemotherapy combined with aggressively attempted R0 resection). We aimed to review the molecular characteristics of DSRCTs to explore therapeutic opportunities for this extremely rare and aggressive cancer type.

Rapamycin attenuates BAFF-extended proliferation and survival via disruption of mTORC1/2 signaling in normal and neoplastic B-lymphoid cells

B cell activating factor from the TNF family (BAFF) stimulates B-cell proliferation and survival, but excessive BAFF promotes the development of aggressive B cells leading to malignant and autoimmune diseases. Recently, we have reported that rapamycin, a macrocyclic lactone, attenuates human soluble BAFF (hsBAFF)-stimulated B-cell proliferation/survival by suppressing mTOR-mediated PP2A-Erk1/2 signaling pathway. Here, we show that the inhibitory effect of rapamycin on hsBAFF-promoted B cell proliferation/survival is also related to blocking hsBAFF-stimulated phosphorylation of Akt, S6K1, and 4E-BP1, as well as expression of survivin in normal and B-lymphoid (Raji and Daudi) cells. It appeared that both mTORC1 and mTORC2 were involved in the inhibitory activity of rapamycin, as silencing raptor or rictor enhanced rapamycin's suppression of hsBAFF-induced survivin expression and proliferation/viability in B cells. Also, PP242, an mTORC1/2 kinase inhibitor, repressed survivin expression, and cell proliferation/viability more potently than rapamycin (mTORC1 inhibitor) in B cells in response to hsBAFF. Of interest, ectopic expression of constitutively active Akt (myr-Akt) or constitutively active S6K1 (S6K1-ca), or downregulation of 4E-BP1 conferred resistance to rapamycin's attenuation of hsBAFF-induced survivin expression and B-cell proliferation/viability, whereas overexpression of dominant negative Akt (dn-Akt) or constitutively hypophosphorylated 4E-BP1 (4EBP1-5A), or downregulation of S6K1, or co-treatment with Akt inhibitor potentiated the inhibitory effects of rapamycin. The findings indicate that rapamycin attenuates excessive hsBAFF-induced cell proliferation/survival via blocking mTORC1/2 signaling in normal and neoplastic B-lymphoid cells. Our data underscore that rapamycin may be a potential agent for preventing excessive BAFF-evoked aggressive B-cell malignancies and autoimmune diseases.

Ciclopirox olamine inhibits mTORC1 signaling by activation of AMPK

Ciclopirox olamine (CPX), an off-patent antifungal agent, has recently been identified as a potential anticancer agent. The mammalian target of rapamycin (mTOR) is a central controller of cell growth, proliferation and survival. Little is known about whether and how CPX executes its anticancer action by inhibiting mTOR. Here we show that CPX inhibited the phosphorylation of p70 S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E binding protein 1 (4E-BP1), two downstream effector molecules of mTOR complex 1 (mTORC1), in a spectrum of human tumor cells, indicating that CPX inhibits mTORC1 signaling. Using rhabdomyosarcoma cells as an experimental model, we found that expression of constitutively active mTOR (E2419K) conferred resistance to CPX inhibition of cell proliferation, suggesting that CPX inhibition of mTORC1 contributed to its anticancer effect. In line with this, treatment with CPX inhibited tumor growth and concurrently suppressed mTORC1 signaling in RD xenografts. Mechanistically, CPX inhibition of mTORC1 was neither via inhibition of IGF-I receptor or phosphoinositide 3-kinase (PI3K), nor by activation of phosphatase and tensin homolog (PTEN). Instead, CPX inhibition of mTORC1 was attributed to activation of AMP-activated protein kinase (AMPK)-tuberous sclerosis complexes (TSC)/raptor pathways. This is supported by the findings that CPX activated AMPK; inhibition of AMPK with Compound C or ectopic expression of dominant negative AMPKα partially prevented CPX from inhibiting mTORC1; silencing TSC2 attenuated CPX inhibition of mTORC1; and CPX also increased AMPK-mediated phosphorylation of raptor (S792). Therefore, the results indicate that CPX exerts the anticancer effect by activating AMPK, resulting in inhibition of mTORC1 signaling.

Functionally conserved effects of rapamycin exposure on zebrafish

Mechanistic target of rapamycin (mTOR) is a conserved serine/threonine kinase important in cell proliferation, growth and protein translation. Rapamycin, a well‑known anti‑cancer agent and immunosuppressant drug, inhibits mTOR activity in different taxa including zebrafish. In the present study, the effect of rapamycin exposure on the transcriptome of a zebrafish fibroblast cell line, ZF4, was investigated. Microarray analysis demonstrated that rapamycin treatment modulated a large set of genes with varying functions including protein synthesis, assembly of mitochondrial and proteasomal machinery, cell cycle, metabolism and oxidative phosphorylation in ZF4 cells. A mild however, coordinated reduction in the expression of proteasomal and mitochondrial ribosomal subunits was detected, while the expression of numerous ribosomal subunits increased. Meta‑analysis of heterogeneous mouse rapamycin microarray datasets enabled the comparison of zebrafish and mouse pathways modulated by rapamycin, using Kyoto Encyclopedia of Genes and Genomes and Gene Ontology pathway analysis. The analyses demonstrated a high degree of functional conservation between zebrafish and mice in response to rapamycin. In addition, rapamycin treatment resulted in a marked dose‑dependent reduction in body size and pigmentation in zebrafish embryos. The present study is the first, to the best of our knowledge, to evaluate the conservation of rapamycin‑modulated functional pathways between zebrafish and mice, in addition to the dose‑dependent growth curves of zebrafish embryos upon rapamycin exposure.

Influence of osteoarthritis grade on molecular signature of human cartilage

Articular chondrocytes maintain cartilage matrix turnover and have the capacity for anabolic and catabolic activities that can be influenced by injury and disease. This study tested the hypothesis that catabolic genes are upregulated with regional osteoarthritis (OA) disease severity within a joint. With IRB approval, specimens of knee cartilage obtained as discarded tissues from subjects undergoing arthroplasty were partitioned for each subject by OA disease severity and evaluated for gene expression by RT-PCR. There was regional OA grade-associated upregulation of expected inflammatory mediators TNF-α, TNF receptors, IFN-γ, and interleukins as well as genes encoding proteolytic enzymes, including Adamts-5 and MMPs. Osteoclast-related genes, cathepsin K, tartrate-resistant acid phosphatase (TRAP), RANKL, RANK, M-CSF, and c-fms, but not osteoprotegerin, were induced in advanced grades. In vitro treatment of normal human chondrocytes with interleukin-1β upregulated similar genes; this provides evidence that chondrocytes per se can be the source of osteoclast-related factors. Immunohistochemical staining showed that RANK- and RANKL-positive cells were abundant in advanced grades, especially in chondrocyte clusters. This suggests a possible autocrine mechanism by which an osteoclast phenotype is induced in articular chondrocytes. In sum, these studies identified gene expression signatures in human OA cartilage based upon regional disease severity within a joint. There was an effect of OA Grade on expression of osteoclastic lytic enzymes and regulatory factors in human articular chondrocytes. Induction of an osteoclast-like phenotype in chondrocytes may be part of OA progression and suggests specific therapeutic approaches.

Desmoplastic small round cell tumor 20 years after its discovery

Desmoplastic small round cell tumor (DSRCT) was proposed as a distinct disease entity by William L Gerald and Juan Rosai in 1991. Over 850 patients have been reported in the medical literature. A specific translocation, t(11;22)(p13;q12), is seen in almost all cases, juxtaposing the EWS gene to the WT1 tumor suppressor gene. DSRCT is composed of nests of small round cells with polyphenotypic differentiation, typically a mixture of epithelial, mesenchymal and neural features, surrounded by a prominent desmoplastic stroma. DSRCT has a predilection for adolescent and young adult males, and primarily involves the abdominal cavity and pelvis. Survival is low despite their initial response to multimodal treatment. Most patients relapse with disseminated disease that is unresponsive to further therapy.

Direct Activation of Bax Protein for Cancer Therapy

Bax, a central cell death regulator, is an indispensable gateway to mitochondrial dysfunction and a major proapoptotic member of the B-cell lymphoma 2 (Bcl-2) family proteins that control apoptosis in normal and cancer cells. Dysfunction of apoptosis renders the cancer cell resistant to treatment as well as promotes tumorigenesis. Bax activation induces mitochondrial membrane permeabilization, thereby leading to the release of apoptotic factor cytochrome c and consequently cancer cell death. A number of drugs in clinical use are known to indirectly activate Bax. Intriguingly, recent efforts demonstrate that Bax can serve as a promising direct target for small-molecule drug discovery. Several direct Bax activators have been identified to hold promise for cancer therapy with the advantages of specificity and the potential of overcoming chemo- and radioresistance. Further investigation of this new class of drug candidates will be needed to advance them into the clinic as a novel means to treat cancer.

Rapamycin inhibits BAFF-stimulated cell proliferation and survival by suppressing mTOR-mediated PP2A-Erk1/2 signaling pathway in normal and neoplastic B-lymphoid cells

B-cell activating factor (BAFF) is involved in not only physiology of normal B cells, but also pathophysiology of aggressive B cells related to malignant and autoimmune diseases. Rapamycin, a lipophilic macrolide antibiotic, has recently shown to be effective in the treatment of human lupus erythematosus. However, how rapamycin inhibits BAFF-stimulated B-cell proliferation and survival has not been fully elucidated. Here, we show that rapamycin inhibited human soluble BAFF (hsBAFF)-induced cell proliferation and survival in normal and B-lymphoid (Raji and Daudi) cells by activation of PP2A and inactivation of Erk1/2. Pretreatment with PD98059, down-regulation of Erk1/2, expression of dominant negative MKK1, or overexpression of wild-type PP2A potentiated rapamycin's suppression of hsBAFF-activated Erk1/2 and B-cell proliferation/viability, whereas expression of constitutively active MKK1, inhibition of PP2A by okadaic acid, or expression of dominant negative PP2A attenuated the inhibitory effects of rapamycin. Furthermore, expression of a rapamycin-resistant and kinase-active mTOR (mTOR-T), but not a rapamycin-resistant and kinase-dead mTOR-T (mTOR-TE), conferred resistance to rapamycin's effects on PP2A, Erk1/2 and B-cell proliferation/viability, implying mTOR-dependent mechanism involved. The findings indicate that rapamycin inhibits BAFF-stimulated cell proliferation/survival by targeting mTOR-mediated PP2A-Erk1/2 signaling pathway in normal and neoplastic B-lymphoid cells. Our data highlight that rapamycin may be exploited for preventing excessive BAFF-induced aggressive B-cell malignancies and autoimmune diseases.

Myeloablative chemotherapy with autologous stem cell transplant for desmoplastic small round cell tumor

Desmoplastic small round cell tumor (DSRCT), a rare, aggressive neoplasm, has a poor prognosis. In this prospective study, we evaluated the role of myeloablative chemotherapy, followed by autologous stem cell transplant in improving survival in DSRCT. After high-dose induction chemotherapy and surgery, 19 patients with chemoresponsive DSRCT underwent autologous stem cell transplant. Myeloablative chemotherapy consisted of carboplatin (400–700 mg/m²/day for 3 days) + thiotepa (300 mg/m²/day for 3 days) ± topotecan (2 mg/m²/day for 5 days). All patients were engrafted and there was no treatment-related mortality. Seventeen patients received radiotherapy to sites of prior or residual disease at a median of 12 weeks after transplant. Five-year event-free and overall survival were 11 ± 7% and 16 ± 8%, respectively. Two patients survive disease-free 16 and 19 years after transplant (both in complete remission before transplant). 14 patients had progression and died of disease at a median of 18 months following autologous transplant. These data do not justify the use of myeloablative chemotherapy with carboplatin plus thiotepa in patients with DSRCT. Alternative therapies should be considered for this aggressive neoplasm.

Rapamycin treatment during in vitro maturation of oocytes improves embryonic development after parthenogenesis and somatic cell nuclear transfer in pigs

This study was conducted to investigate the effects of rapamycin treatment during in vitro maturation (IVM) on oocyte maturation and embryonic development after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT) in pigs. Morphologically good (MGCOCs) and poor oocytes (MPCOCs) were untreated or treated with 1 nM rapamycin during 0-22 h, 22-42 h, or 0-42 h of IVM. Rapamycin had no significant effects on nuclear maturation and blastocyst formation after PA of MGCOCs. Blastocyst formation after PA was significantly increased by rapamycin treatment during 22-42 h and 0-42 h (46.6% and 46.5%, respectively) relative to the control (33.3%) and 0-22 h groups (38.6%) in MPCOCs. In SCNT, blastocyst formation tended to increase in MPCOCs treated with rapamycin during 0-42 h of IVM relative to untreated oocytes (20.3% vs. 14.3%, 0.05 < p < 0.1), while no improvement was observed in MGCOCs. Gene expression analysis revealed that transcript abundance of Beclin 1 and microtubule-associated protein 1 light chain 3 mRNAs was significantly increased in MPCOCs by rapamycin relative to the control. Our results demonstrated that autophagy induction by rapamycin during IVM improved developmental competence of oocytes derived from MPCOCs.

Multimodal treatment of abdominal and pelvic desmoplastic small round cell tumor with relative good prognosis

OBJECTIVE

To investigate the clinicopathologic features and survival outcomes of desmoplastic small round cell tumor (DSCRT).

METHODS

The retrospective cohort study was performed on clinical and pathological data of 18 DSCRT patients. Among them, two subgroups were classified according to treatment modalities. 10 cases underwent operation and adjuvant chemotherapy (group 1, 10/18, 55.6%) and 8 cases were diagnosed by fine needle aspiration biopsy without surgical intervention (group 2, 8/18, 44.4%). All cases received six courses of multiple agents chemotherapy.

RESULTS

All cases were histologically confirmed as DSRCT and Cox regression revealed that sex, tumor localization and treatment modality affected patient outcomes. Kaplan-Meier analysis revealed that the median survival time was 22.0 ± 4.0 mo in group 1 versus 9.0 ± 0.7 mo in group 2.

CONCLUSION

DSRCT is highly aggressive malignance with poor prognosis, surgical excision with combination of chemotherapy can significantly improve the survival outcomes.

Cytotoxic activity of sunitinib and everolimus in Caki-1 renal cancer cells is accompanied by modulations in the expression of apoptosis-related microRNA clusters and BCL2 family genes

Sunitinib and everolimus are two of the antineoplastic agents indicated for the management of metastatic renal cancer. Although both of the above compounds were primarily designed as antiangiogenic factors, preclinical studies claim that these drugs can also trigger apoptosis. Herein, we sought to evaluate the cytotoxic activity of sunitinib and everolimus against renal cancer cells Caki-1 and moreover to assess their impact on the expression levels of three BCL2 family members and three apoptosis-related microRNA clusters upon incubation with the drugs or following recovery from treatment. The cytotoxic effect of sunitinib and everolimus on Caki-1 cells' viability was estimated by the MTT assay, while cleaved PARP, assayed via Western Blotting, served as a marker of programmed cell death. As for the expression levels of the BCL2 family members BCL2, BAX and BCL2L12 and those of the mature microRNAs of the miR-183/96/182, miR-143/145, and miR-15a/16 clusters, they were quantified via real-time PCR. Our results showed that both agents induced a time- and dose-dependent decrease in cell viability and promoted cleavage of PARP. In parallel, significant modulations were observed in the expression levels of miR-145, miR-15a, and miR-16 in case of sunitinib, whereas BCL2, BAX, miR-145 and miR-15a expression was strongly affected by everolimus. Overall, our data support the notion that sunitinib and everolimus are able to directly induce cell death in renal cancer cells and simultaneously affect the expression levels of their apoptosis-related microRNAs and BCL2 family members upon this process.

Phase I study and preclinical efficacy evaluation of the mTOR inhibitor sirolimus plus gemcitabine in patients with advanced solid tumours

Background:

We conducted a phase I study in patients with advanced solid tumours to identify the recommended dose, assess pharmacokinetics (PK), pharmacodynamic activity and preclinical antitumour efficacy of the combination of sirolimus and gemcitabine.

Methods:

Nineteen patients were treated with sirolimus 2 or 5 mg daily and gemcitabine 800 or 1000 mg m⁻² on days 1 and 8. Dose escalation depended on dose-limiting toxicity (DLT) rate during the first 3-week period. Paired skin biopsies were evaluated for phosphorylated S6 (pS6) as marker of mTOR (mammalian target of rapamycin) inhibition. Pharmacokinetics and preclinical evaluation of efficacy using two different sarcoma cell lines and leiomyosarcoma xenografts were also conducted.

Results:

Three DLTs were observed: grade 3 transaminitis, grade 3 thrombocytopenia and grade 4 thrombocytopenia. Common treatment-related adverse events included anaemia, neutropenia, thrombocytopenia and transaminitis. Pharmacodynamic analyses demonstrated mTOR inhibition with sirolimus 5 mg and PK showed no influence of sirolimus concentrations on gemcitabine clearance. In vitro and in vivo studies suggested mTOR pathway hyperactivation by gemcitabine that was reversed by sirolimus. Tumour growth in leiomyosarcoma xenografts was dramatically inhibited by the treatment.

Conclusions:

Recommended dose was sirolimus 5 mg per 24 h plus gemcitabine 800 mg m⁻². Antitumour activity in preclinical sarcoma models and mTOR signalling inhibition were observed. A phase II study is currently ongoing.

Desmoplastic small round cell tumor of the abdomen and pelvis: clinicopathological characters of 12 cases

Purpose. To study the clinical, radiological, and pathological characteristics of abdominal desmoplastic small round cell tumor (DSRCT) and investigate the optimal therapy modalities. Patients and Methods. A retrospective cohort study was performed on 12 abdominal DSRCT patients; all pathological, radiological, and prognostic data were analyzed. There were 3 patients (25%) with metastatic disease at presentation. In all 12 cases, 6 cases underwent operation and adjuvant chemotherapy (group 1, 6/12, 50%). The other 6 cases were diagnosed by fine needle aspiration or exploratory laparotomy biopsy (group 2, 6/12, 50%); all cases received four to six courses of multiple agents chemotherapy, respectively. Results. All cases were finally diagnosed as DSRCT pathologically. Among group 1, all cases underwent en bloc resection (2/6, 33%) or tumor debulking (4/6, 67%) and, following four courses of multiple agents chemotherapy, Kaplan-Meier analysis revealed that 3-year survival was 50% in group 1 versus 16.7% in group 2 (P < 0.05). Gross tumor resection was highly significant in prolonging overall survival; patients with localized solitary lesion have a better prognosis, most likely due to increased feasibility of resection. Conclusions. DSRCT is a rare malignant tumor with poor prognosis. Surgical excision with combination chemotherapy as an adjunct is mandatory for nonmetastatic cases because these modalities used in isolation may have less impact.

Melatonin combined with endoplasmic reticulum stress induces cell death via the PI3K/Akt/mTOR pathway in B16F10 melanoma cells

This study investigated B16F10 melanoma cell death induced by melatonin combined with endoplasmic reticulum (ER) stress through the PI3K/Akt/mTOR pathway. Cell viability was significantly decreased after treatment with melatonin combined with ER stress from thapsigargin or tunicamycin compared to no treatment or treatment with melatonin only. Combined melatonin and ER stress also significantly reduced expression of p85β, p-Akt (Ser473, Thr308), and p-mTOR (Ser2448, Ser2481) compared to treatment with melatonin only. The ER stress protein p-PERK and p-eIF2α were significantly increased under combined melatonin and ER stress treatment compared to no treatment or treatment with melatonin only. Combined melatonin and ER stress significantly reduced Bcl-2 protein and augmented Bax protein compared to melatonin-only treatment. Also, the combined treatment significantly lowered expression of catalase, Cu/Zn-SOD, and Mn-SOD proteins compared to melatonin only. Expression of p85β was significantly more decreased under treatment with melatonin and thapsigargin or tunicamycin plus the PI3K inhibitors LY294002 or wortmannin than under treatment with only melatonin or a PI3K inhibitor. The PI3K downstream target p-Akt (Ser473, Thr308) showed significantly decreased expression under treatment with melatonin and thapsigargin or tunicamycin plus PI3K inhibitors than under treatment with melatonin or PI3K inhibitors only. These results indicate that survival of B16F10 melanoma cells after combined treatment with melatonin and ER stress inducers is suppressed through regulation of the PI3K/Akt/mTOR pathway. Melatonin combined with thapsigargin or tunicamycin appears to be a promising strategy for effective melanoma treatment.

Inhibition of hypoxia-induced proliferation of pulmonary arterial smooth muscle cells by a mTOR siRNA-loaded cyclodextrin nanovector

The proliferation of pulmonary arterial smooth muscle cells (PASMCs) is a key pathophysiological component of vascular remodeling in pulmonary arterial hypertension (PAH), an intractable disease, for which pharmacotherapy is limited and only slight improvement in survival outcomes have achieved over the past few decades. RNA interference provides a highly promising strategy to the treatment of this chronic lung disease, while efficient delivery of small interfering RNA (siRNA) remains a key challenge for the development of clinically acceptable siRNA therapeutics. With the aim to construct useful nanomedicines, the mammalian target of rapamycin (mTOR) siRNA was loaded into hybrid nanoparticles based on low molecular weight (Mw) polyethylenimine (PEI) and a pH-responsive cyclodextrin material (Ac-aCD) or poly(lactic-co-glycolic acid) (PLGA). This hybrid nanoplatform gave rise to desirable siRNA loading, and the payload release could be modulated by the hydrolysis characteristics of carrier materials. Fluorescence observation and flow cytometry quantification suggested that both Ac-aCD and PLGA nanovectors (NVs) may enter PASMCs under either normoxia or hypoxia conditions as well as in the presence of serum, with uptake and transfection efficiency significantly higher than those of cationic vectors such as PEI with Mw of 25 kDa (PEI25k) and Lipofectamine 2000 (Lipo 2k). Hybrid Ac-aCD or PLGA NV containing siRNA remarkably inhibited proliferation and activated apoptosis of hypoxic PASMCs, largely resulting from effective suppression of mTOR signaling as evidenced by significantly lowered expression of mTOR mRNA and phosphorylated protein. Moreover, these hybrid nanomedicines were more effective than commonly used cationic vectors like PEI25k and Lipo 2k, with respect to cell growth inhibition, apoptosis activation, and expression attenuation of mTOR mRNA and protein. Therefore, mTOR siRNA nanomedicines based on hybrid Ac-aCD or PLGA NV may be promising therapeutics for diseases related to hypoxic abnormal growth of PASMCs.

The rationale of targeting mammalian target of rapamycin for ischemic stroke

Given the current limitation of therapeutic approach for ischemic stroke, a leading cause of disability and mortality in the developed countries, to develop new therapeutic strategies for this devastating disease is urgently necessary. As a serine/threonine kinase, mammalian target of rapamycin (mTOR) activation can mediate broad biological activities that include protein synthesis, cytoskeleton organization, and cell survival. mTOR functions through mTORC1 and mTORC2 complexes and their multiple downstream substrates, such as eukaryotic initiation factor 4E-binding protein 1, p70 ribosomal S6 kinase, sterol regulatory element-binding protein 1, hypoxia inducible factor-1, and signal transducer and activator transcription 3, Yin Ying 1, Akt, protein kinase c-alpha, Rho GTPase, serum-and gucocorticoid-induced protein kinase 1, etc. Specially, the role of mTOR in the central nervous system has been attracting considerable attention. Based on the ability of mTOR to prevent neuronal apoptosis, inhibit autophagic cell death, promote neurogenesis, and improve angiogenesis, mTOR may acquire the capability of limiting the ischemic neuronal death and promoting the neurological recovery. Consequently, to regulate the activity of mTOR holds a potential as a novel therapeutic strategy for ischemic stroke.

Arenobufagin, a natural bufadienolide from toad venom, induces apoptosis and autophagy in human hepatocellular carcinoma cells through inhibition of PI3K/Akt/mTOR pathway

Hepatocellular carcinoma (HCC) is a deadly form of cancer without effective chemotherapy so far. Currently, only sorafenib, a multitargeted tyrosine kinase inhibitor, slightly improves survival in HCC patients. In searching for natural anti-HCC components from toad venom, which is frequently used in the treatment of liver cancer in traditional Chinese medicine, we discovered that arenobufagin, a bufadienolide from toad venom, had potent antineoplastic activity against HCC HepG2 cells as well as corresponding multidrug-resistant HepG2/ADM cells. We found that arenobufagin induced mitochondria-mediated apoptosis in HCC cells, with decreasing mitochondrial potential, as well as increasing Bax/Bcl-2 expression ratio, Bax translocation from cytosol to mitochondria. Arenobufagin also induced autophagy in HepG2/ADM cells. Autophagy-specific inhibitors (3-methyladenine, chloroquine and bafilomycin A1) or Beclin1 and Atg 5 small interfering RNAs (siRNAs) enhanced arenobufagin-induced apoptosis, indicating that arenobufagin-mediated autophagy may protect HepG2/ADM cells from undergoing apoptotic cell death. In addition, we observed the inhibition of phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway by arenobufagin. Interestingly, inhibition of mTOR by rapamycin or siRNA duplexes augmented arenobufagin-induced apoptosis and autophagy. Finally, arenobufagin inhibited the growth of HepG2/ADM xenograft tumors, which were associated with poly (ADP-ribose) polymerase cleavage, light chain 3-II activation and mTOR inhibition. In summary, we first demonstrated the antineoplastic effect of arenobufagin on HCC cells both in vitro and in vivo. We elucidated the underlying antineoplastic mechanisms of arenobufagin that involve cross talk between apoptosis and autophagy via inhibition of the PI3K/Akt/mTOR pathway. This study may provide a rationale for future clinical application using arenobufagin as a chemotherapeutic agent for HCC.

Rapamycin delays disease onset and prevents PrP plaque deposition in a mouse model of Gerstmann-Sträussler-Scheinker disease

Autophagy is a cell survival response to nutrient deprivation that delivers cellular components to lysosomes for digestion. In recent years, autophagy has also been shown to assist in the degradation of misfolded proteins linked to neurodegenerative disease (Ross and Poirier, 2004). In support of this, rapamycin, an autophagy inducer, improves the phenotype of several animal models of neurodegenerative disease. Our Tg(PrP-A116V) mice model Gerstmann-Sträussler-Scheinker disease (GSS), a genetic prion disease characterized by prominent ataxia and extracellular PrP amyloid plaque deposits in brain (Yang et al., 2009). To determine whether autophagy induction can mitigate the development of GSS, Tg(PrP-A116V) mice were chronically treated with 10 or 20 mg/kg rapamycin intraperitoneally thrice weekly, beginning at 6 weeks of age. We observed a dose-related delay in disease onset, a reduction in symptom severity, and an extension of survival in rapamycin-treated Tg(PrP-A116V) mice. Coincident with this response was an increase in the autophagy-specific marker LC3II, a reduction in insoluble PrP-A116V, and a near-complete absence of PrP amyloid plaques in the brain. An increase in glial cell apoptosis of unclear significance was also detected. These findings suggest autophagy induction enhances elimination of misfolded PrP before its accumulation in plaques. Because ataxia persisted in these mice despite the absence of plaque deposits, our findings also suggest that PrP plaque pathology, a histopathological marker for the diagnosis of GSS, is not essential for the GSS phenotype.

Enteric-delivered rapamycin enhances resistance of aged mice to pneumococcal pneumonia through reduced cellular senescence

Rapamycin, a potent immunomodulatory drug, has shown promise in the amelioration of numerous age-associated diseases including cancer, Alzheimer's disease and cardiac hypertrophy. Yet the elderly, the population most likely to receive therapeutic rapamycin, are already at increased risk for infectious disease; thus concern exists that rapamycin may exacerbate age-associated immune dysfunctions and worsen infection outcomes. Herein, we examined the impact of enteric delivered rapamycin monotherapy (eRapa) on the susceptibility of aged (22-24month) C57BL/6 mice to Streptococcus pneumoniae, the leading bacterial cause of community-acquired pneumonia. Following challenge with S. pneumoniae, administration of eRapa conferred modest protection against mortality. Reduced mortality was the result of diminished lung damage rather than reduced bacterial burden. eRapa had no effect on basal levels of Interleukin (IL)-1α, IL-6, IL-10, IL-12p70, KC, Interferon-γ, Tumor necrosis factor α and Monocyte chemotactic protein-1 in whole lung homogenates or during pneumococcal pneumonia. Previously we have demonstrated that cellular senescence enhances permissiveness for bacterial pneumonia through increased expression of the bacterial ligands Laminin receptor (LR), Platelet-activating factor receptor (PAFr) and Cytokeratin 10 (K10). These proteins are co-opted by S. pneumoniae and other respiratory tract pathogens for host cell attachment during lung infection. UM-HET3 mice on eRapa had reduced lung cellular senescence as determined by levels of the senescence markers p21 and pRB, but not mH2A.1. Mice on eRapa also had marked reductions in PAFr, LR, and K10. We conclude that eRapa protected aged mice against pneumonia through reduced lung cellular senescence, which in turn, lowered bacterial ligand expression.

Autophagy influences maternal mRNA degradation and apoptosis in porcine parthenotes developing in vitro

Autophagy, an essential process for cellular maintenance, cell viability, and development, is the bulk degradation of proteins and organelles. This study investigated the expression levels of autophagy-related genes and the effect of 3-methyladenine (3-MA, an autophagy inhibitor) or rapamycin (an autophagy inducer) on maternal gene degradation and apoptosis in porcine parthenotes developing in vitro. LC3, which is essential for the formation of autophagosomes, was widely expressed in porcine parthenotes. High levels of autophagy-related genes, Atg5, Beclin1 and Lc3 transcripts were expressed in the 1-cell (1C) stage and gradually decreased through the 2-cell (2C) to blastocyst stages. The mRNA expression of Gdf9, c-mos and cyclin B maintained high levels in 2C and 4-cell (4C) embryos treated with 3-MA compared with the control. The Bmp15 and cyclin B mRNA levels were significantly reduced in embryos treated with rapamycin compared with the control. These results suggest that autophagy influences the degradation of these maternal genes. Furthermore, 3-MA-treated embryos exhibited significantly reduced developmental rates, decreased total cell numbers and increased rates of apoptosis. Expression of Atg5, Beclin1 and Lc3 and synthesis of LC3 protein were significantly reduced at the blastocyst stage. Although rapamycin treatment did not affect the developmental rate, it decreased the cell number and increased the rate of apoptosis, and the expression of Atg5, Beclin1 and Lc3 and LC3 protein synthesis were increased. Finally, blastocysts derived following treatment with 3-MA or rapamycin exhibited significantly decreased expression of selected transcription factors, including Pou5f1, Sox2 and Nanog. In conclusion, our results demonstrate that autophagy influences maternal mRNA degradation and apoptosis at the blastocyst stage and suggest that autophagy plays an important role in early embryo development in the pig.

Desmoplastic small round cell tumors with EWS-WT1 fusion transcript in children and young adults

BACKGROUND

The presence of the EWS-WT1 gene fusion transcript (GFT) is characteristic of desmoplastic small round cell tumor (DSRCT), a rare and very aggressive disease for which the treatment has not yet been clearly standardized.

METHODS

This was a retrospective national multicenter analysis of young patients <30 years with tumors expressing the EWS-WT1-GFT, designed to determine whether extensive surgery had an impact on survival.

RESULTS

Between 1995 and 2006, a EWS-WT1-GFT was detected in the tumors of 38 patients, 17 (44.7%) of whom had had a different initial pathologic diagnosis prior to molecular testing. Mean age was 13.2 years (range: 4-29.7 years). Only 9 patients (24%) had localized disease. Treatment was heterogeneous. Nine patients had "limited" surgical resections and 22 underwent "extensive" surgery. Two-year event-free survival and overall survival were 14.4% and 50%, respectively. Among the five patients who were alive in complete remission, four had undergone extensive and complete surgery.

CONCLUSIONS

Detection of the EWS-WT1-GFT plays a major role in the diagnosis of DSRCT. No survival difference was observed according to extent of surgery, but complete surgery seemed to offer the best chance of long-term survival. High-dose chemotherapy or local radiotherapy did not appear to improve survival in this retrospective analysis, but larger prospective studies are needed to provide definitive conclusions on the role of these treatments.

Results of a phase II study of sirolimus and cyclophosphamide in patients with advanced sarcoma

BACKGROUND

Activation of the mammalian target of rapamycin (mTOR) pathway has been demonstrated in sarcoma. Trials using mTOR inhibitor in sarcoma have shown low objective response rates but progression-free survival (PFS) rates suggest cytostatic effects. The combination of sirolimus and cyclophosphamide demonstrated synergistic anti-sarcoma activity in preclinical models; therefore, we conducted a phase II trial of sirolimus and cyclophosphamide in patients with advanced sarcoma.

METHODS

Patients received 4 mg sirolimus daily and 200mg cyclophosphamide d1-7 and 15-21 every 28 days. The primary objective was to estimate the 24-week PFS rate with a target of ≥ 25%. Patients were followed for World Health Organisation (WHO) criteria tumour response by imaging every 8 weeks. Serum levels of sirolimus, lipids and vascular endothelial growth factor were measured. Tumour tissue was analysed for mTOR, S6 ribosomal protein and cytochrome P450 3A4/5 by quantitative immunofluorescence.

RESULTS

Forty-nine eligible patients were enrolled from September 2008 to December 2009. Patients received a median of four cycles of therapy. Starting doses of drugs were tolerated in 79%. One patient achieved partial tumour response, 10 were progression-free for ≥ 24 weeks and two completed 12 cycles of treatment. Median PFS and overall survival (OS) were 3.4 and 9.9 months, respectively. Serious adverse events attributed to therapy occurred in 11% and included infection, pneumonitis and thrombosis. Hypertriglyceridaemia from treatment and lower tumour phosphorylated-mTOR are associated with longer survival.

CONCLUSIONS

Sirolimus and cyclophosphamide were tolerated by the majority of patients. About 20% of patients had stable sarcoma for at least 6 months but objective tumour response was infrequent.

Fighting neurodegeneration with rapamycin: mechanistic insights

A growing number of studies point to rapamycin as a pharmacological compound that is able to provide neuroprotection in several experimental models of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Huntington's disease and spinocerebellar ataxia type 3. In addition, rapamycin exerts strong anti-ageing effects in several species, including mammals. By inhibiting the activity of mammalian target of rapamycin (mTOR), rapamycin influences a variety of essential cellular processes, such as cell growth and proliferation, protein synthesis and autophagy. Here, we review the molecular mechanisms underlying the neuroprotective effects of rapamycin and discuss the therapeutic potential of this compound for neurodegenerative diseases.

Effects of 25-hydroxyvitamin D(3) on proliferation and osteoblast differentiation of human marrow stromal cells require CYP27B1/1α-hydroxylase

1,25-Dihydroxyvitamin D(3)[1,25(OH)(2)D(3)] has many noncalcemic actions that rest on inhibition of proliferation and promotion of differentiation in malignant and normal cell types. 1,25(OH)(2)D(3) stimulates osteoblast differentiation of human marrow stromal cells (hMSCs), but little is known about the effects of 25-hydroxyvitamin D(3)[25(OH)D(3)] on these cells. Recent evidence shows that hMSCs participate in vitamin D metabolism and can activate 25(OH)D(3) by CYP27B1/1α-hydroxylase. These studies test the hypothesis that antiproliferative and prodifferentiation effects of 25(OH)D(3) in hMSCs depend on CYP27B1. We studied hMSCs that constitutively express high (hMSCs(hi-1α) ) or low (hMSCs(lo-1α)) levels of CYP27B1 with equivalent expression of CYP24A1 and vitamin D receptor. In hMSCs(hi-1α), 25(OH)D(3) reduced proliferation, downregulated proliferating cell nuclear antigen (PCNA), upregulated p21(Waf1/Cip1), and decreased cyclin D1. Unlike 1,25(OH)(2)D(3), the antiapoptotic effects of 25(OH)D(3) on Bax and Bcl-2 were blocked by the P450 inhibitor ketoconazole. The antiproliferative effects of 25(OH)D(3) in hMSCs(hi-1α) and of 1,25(OH)(2)D(3) in both samples of hMSCs were explained by cell cycle arrest, not by increased apoptosis. Stimulation of osteoblast differentiation in hMSCs(hi-1α) by 25(OH)D(3) was prevented by ketoconazole and upon transfection with CYP27B1 siRNA. These data indicate that CYP27B1 is required for 25(OH)D(3)'s action in hMSCs. Three lines of evidence indicate that CYP27B1 is required for the antiproliferative and prodifferentiation effects of 25(OH)D(3) on hMSCs: Those effects were not seen (1) in hMSCs with low constitutive expression of CYP27B1, (2) in hMSCs treated with ketoconazole, and (3) in hMSCs in which CYP27B1 expression was silenced. Osteoblast differentiation and skeletal homeostasis may be regulated by autocrine/paracrine actions of 25(OH)D(3) in hMSCs.

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.

Human CD34-derived myeloid dendritic cell development requires intact phosphatidylinositol 3-kinase-protein kinase B-mammalian target of rapamycin signaling

Dendritic cells (DCs) are composed of different subsets that exhibit distinct functionality in the induction and regulation of immune responses. The myeloid DC subsets, including interstitial DCs and Langerhans cells (LCs), develop from CD34+ hematopoietic progenitors via direct DC precursors or monocytes. The molecular mechanisms regulating DC development are still largely unknown and mostly studied in mice. Phosphatidylinositol 3-kinase (PI3K) regulates multiple processes in myeloid cells. This study investigated the role of PI3K signaling in the development of human CD34-derived myeloid DCs. Pharmacologic inhibition of PI3K or one of its downstream targets mTOR reduced interstitial DC and LC numbers in vitro. Increased activity of this signaling module by introduction of constitutively active protein kinase B (PKB/c-Akt) increased the yields of human DC precursors in vitro as well as in transplanted beta2-microglobulin-/- NOD/SCID mice in vivo. Signaling inhibition during differentiation did not affect the acquisition of a DC phenotype, whereas proliferation and survival strongly depended on intact PI3K-PKB-mTOR signaling. Interestingly, however, this pathway became redundant for survival regulation upon terminal differentiation, which was associated with an altered expression of apoptosis regulating genes. Although dispensable for costimulatory molecule expression, the PI3K-PKB-mTOR signaling module was required for other important processes associated with DC function, including Ag uptake, LPS-induced cytokine secretion, CCR7 expression, and T cell stimulation. Thus, PI3K-PKB-mTOR signaling plays a crucial role in the development of functional CD34-derived myeloid DCs. These findings could be used as a strategy to manipulate DC subset distribution and function to regulate immunity.

Primary sarcoma of the liver and transplantation: a case study and literature review

Primary sarcomas of the liver are rare tumors and their diagnosis is difficult to assess, particularly on percutaneous liver biopsy. Epithelioid hemangioendothelioma (EHE) is an infrequent indication for liver transplantation, and angiosarcoma (AS) is a widely recognized contraindication because of its poor prognosis. We report the case of a young woman who underwent liver transplantation (LT) for an infiltrative hepatic tumor with several features suggestive of EHE, although the analysis of the native liver revealed AS. Everolimus was used as the main immunosuppressive drug. More than two years after LT, her physical condition remained stable despite a local recurrence at 10 months. In this setting, the ranking of new immunosuppressive agents belonging to the family of the proliferation signal inhibitors will need to be precise, but their intrinsic properties suggest a potential use in treatments after LT for atypical malignancies.

Advances in preclinical small molecules for the treatment of NSCLC

BACKGROUND

NSCLC accounts for 85% of all lung cancer cases and is the leading cause of cancer mortality. Advances in the knowledge of molecular events governing oncogenesis have led to a number of novel therapeutic agents targeting specific pathways critical for tumor growth.

OBJECTIVE

To summarize the recent preclinical developments of small molecules for NSCLC therapy.

METHODS

This review primarily consists of patents and publications between 1997 and 2008.

RESULTS/CONCLUSION

Small molecules with known targets, such as inhibitors for EGFR, VEGF, RAS-RAF-MAP kinase pathway, phosphoinositide 3-kinase pathway, histone deacetylase, protein phosphatase, topoisomerase, cyclin dependent kinases, heat-shock protein, tubulin, DNA and MET are reviewed. Other novel small molecules with potent efficacy without target information are also discussed.

Natural history and therapeutic management of recurrent hepatocellular carcinoma after liver transplantation

While the natural history and appropriate diagnostic and management practices are relatively well defined for hepatocellular carcinoma (HCC), data are scarce concerning the characteristic features and treatment modalities for recurrent HCC after liver transplantation. The time of recurrence appears to impact survival more significantly than localization, but to date, guidelines for therapeutic management of recurrent HCC have not been established. Data in the literature shows that late and unifocal recurrence has a better prognosis when treated by surgery or radiofrequency. In the event of early recurrence, surgery cannot be recommended due to the lack of evidence and the high risk of advanced disease. Systemic therapy can be discussed in a situation of multifocal recurrence. Proliferative signal inhibitors exhibit both immunosuppressive and antiproliferative properties and liver transplantation teams tend to introduce such treatment despite the lack of extensive data.

Synergy between phosphatidylinositol 3-kinase/Akt pathway and Bcl-xL in the control of apoptosis in adenocarcinoma cells of the lung

Adenocarcinomas of the lung commonly show an increase in the activity of phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway, yet many are resistant to apoptosis induced by the inhibition of PI3K. We hypothesized that Bcl-xL would have a synergistic effect on the apoptotic response induced by inhibition of the PI3K/Akt pathway in lung adenocarcinoma. To test this, we examined the effect of the PI3K inhibitor (LY294002) on lung adenocarcinoma cell lines expressing varying levels of Bcl-xL. We found that cells that overexpress Bcl-xL are resistant to LY294002-induced apoptosis, whereas cells that express little Bcl-xL readily are not. Restoring Bcl-xL expression in cells that express low level of Bcl-xL conferred resistance to apoptosis in response to LY294002. The simultaneous inhibition of the PI3K/Akt pathway by LY294002 or Akt1 small interfering RNA and Bcl-xL function by ABT-737 or Bcl-xL small interfering RNA greatly enhanced the apoptotic response. Moreover, this response was associated with the induction of proapoptotic BH3-only Bcl-2 family member Bim. Our data suggest that PI3K/Akt and Bcl-xL pathways control cell death in lung adenocarcinoma cells in a synergistic manner. Modulation of Bcl-xL expression may represent one important strategy to optimize the efficacy of therapeutic agents targeting the PI3K/Akt pathway in adenocarcinoma of the lung.

ABT-263 and rapamycin act cooperatively to kill lymphoma cells in vitro and in vivo

ABT-263 is a potent, orally bioavailable inhibitor of the antiapoptotic Bcl-2 family members Bcl-2, Bcl-x(L), and Bcl-w, which is currently in phase I clinical trials. Previous work has shown that this compound has low nanomolar cell-killing activity in a variety of lymphoma and leukemia cell lines, many of which overexpress Bcl-2 through a variety of mechanisms. Rapamycin is a macrolide antibiotic that inhibits the mammalian target of rapamycin complex, leading to cell cycle arrest and inhibition of protein translation. Rapamycin (and its analogues) has shown activity in a variety of tumor cell lines primarily through induction of cell cycle arrest. Activity has also been shown clinically in mantle cell lymphoma and advanced renal cell carcinoma. Here, we show that treatment of the follicular lymphoma lines DoHH-2 and SuDHL-4 with 100 nmol/L rapamycin induces substantial G(0)-G(1) arrest. Addition of as little as 39 nmol/L ABT-263 to the rapamycin regimen induced a 3-fold increase in sub-G(0) cells. Combination of these agents also led to a significant increase in Annexin V staining over ABT-263 alone. In xenograft models of these tumors, rapamycin induced a largely cytostatic response in the DoHH-2 and SuDHL-4 models. Coadministration with ABT-263 induced significant tumor regression, with DoHH-2 and SuDHL-4 tumors showing 100% overall response rates. Apoptosis in these tumors was significantly enhanced by combination therapy as measured by staining with an antibody specific for cleaved caspase-3. These data suggest that combination of ABT-263 and rapamycin or its analogues represents a promising therapeutic strategy for the treatment of lymphoma.

The dual PI3 kinase/mTOR inhibitor PI-103 prevents p53 induction by Mdm2 inhibition but enhances p53-mediated mitochondrial apoptosis in p53 wild-type AML

Activation of the phosphatidylinositol-3 kinase/Akt/mammalian target of the rapamycin (PI3K/Akt/mTOR) pathway and inactivation of wild-type p53 by murine double minute 2 homologue (Mdm2) overexpression are frequent molecular events in acute myeloid leukemia (AML). We investigated the interaction of PI3K/Akt/mTOR and p53 pathways after their simultaneous blockade using the dual PI3K/mTOR inhibitor PI-103 and the Mdm2 inhibitor Nutlin-3. We found that PI-103, which itself has modest apoptogenic activity, acts synergistically with Nutlin-3 to induce apoptosis in a wild-type p53-dependent fashion. PI-103 synergized with Nutlin-3 to induce Bax conformational change and caspase-3 activation, despite its inhibitory effect on p53 induction. The PI-103/Nutlin-3 combination caused profound dephosphorylation of 4E-BP1 and decreased expression of many proteins including Mdm2, p21, Noxa, Bcl-2 and survivin, which can affect mitochondrial stability. We suggest that PI-103 actively enhances downstream p53 signaling and that a combination strategy aimed at inhibiting PI3K/Akt/mTOR signaling and activating p53 signaling is potentially effective in AML, where TP53 mutations are rare and downstream p53 signaling is intact.

Combined inhibition of MAPK and mTOR signaling inhibits growth, induces cell death, and abrogates invasive growth of melanoma cells

The RAS-RAF-MEK-ERK and PI3K-AKT-mTOR signaling pathways are activated through multiple mechanisms and appear to play a major role in melanoma progression. Herein, we examined whether targeting the RAS-RAF-MEK-ERK pathway with the RAF inhibitor sorafenib and/or the PI3K-AKT-mTOR pathway with the mTOR inhibitor rapamycin has therapeutic effects against melanoma. A combination of sorafenib (4 microM) with rapamycin (10 nM) potentiated growth inhibition in all six metastatic melanoma cell lines tested. The absolute enhancement of growth inhibition rates ranged from 13.0-27.8% in different cell lines (P<0.05, combination treatment vs monotreatment). Similar results were obtained with combinations of the MEK inhibitors U0126 (30 microM) or PD98059 (50 microM) with rapamycin (10 nM). The combined treatment of melanoma cells with sorafenib and rapamycin led to an approximately twofold increase of cell death compared with sorafenib monotreatment (P<0.05) as assessed by propidium iodide staining and cell death detection ELISA. Moreover, sorafenib in combination with rapamycin completely suppressed invasive melanoma growth in organotypic culture mimicking the physiological context. These effects were associated with complete downregulation of the antiapoptotic proteins Bcl-2 and Mcl-1. Sorafenib combined with rapamycin appears to be a promising strategy for the effective treatment of melanoma and merits clinical investigation.

Age-related intrinsic changes in human bone-marrow-derived mesenchymal stem cells and their differentiation to osteoblasts

In vivo and in vitro studies indicate that a subpopulation of human marrow-derived stromal cells (MSCs, also known as mesenchymal stem cells) has potential to differentiate into multiple cell types, including osteoblasts. In this study, we tested the hypothesis that there are intrinsic effects of age in human MSCs (17-90 years). We tested the effect of age on senescence-associated beta-galactosidase, proliferation, apoptosis, p53 pathway genes, and osteoblast differentiation in confluent monolayers by alkaline phosphatase activity and osteoblast gene expression analysis. There were fourfold more human bone MSCs (hMSCs) positive for senescence-associated beta-galactosidase in samples from older than younger subjects (P < 0.001; n = 17). Doubling time of hMSCs was 1.7-fold longer in cells from the older than the younger subjects, and was positively correlated with age (P = 0.002; n = 19). Novel age-related changes were identified. With age, more cells were apoptotic (P = 0.016; n = 10). Further, there were age-related increases in expression of p53 and its pathway genes, p21 and BAX. Consistent with other experiments, there was a significant age-related decrease in generation of osteoblasts both in the STRO-1+ cells (P = 0.047; n = 8) and in adherent MSCs (P < 0.001; n = 10). In sum, there is an age-dependent decrease in proliferation and osteoblast differentiation, and an increase in senescence-associated beta-galactosidase-positive cells and apoptosis in hMSCs. Up-regulation of the p53 pathway with age may have a critical role in mediating the reduction in both proliferation and osteoblastogenesis of hMSCs. These findings support the view that there are intrinsic alterations in human MSCs with aging that may contribute to the process of skeletal aging in humans.