Thyroid hormone inactivation in gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) are resistant to traditional chemotherapy but are responsive to the tyrosine kinase inhibitors imatinib and sunitinib. The use of these agents has improved the outcome for patients but is associated with adverse effects, including hypothyroidism. Multiple mechanisms of this effect have been proposed, including decreased iodine organification and glandular capillary regression. Here we report the finding of consumptive hypothyroidism caused by marked overexpression of the thyroid hormone-inactivating enzyme type 3 iodothyronine deiodinase (D3) within the tumor. Affected patients warrant increased monitoring and may require supernormal thyroid hormone supplementation.

Establishment and characterization of a novel Hodgkin lymphoma cell line, AM-HLH, carrying the Epstein-Barr virus genome integrated into the host chromosome.

We describe the establishment and characterization of a cell line, AM-HLH, obtained from a patient with Epstein-Barr virus-positive (EBV+ ) nodular sclerosis-type Hodgkin lymphoma (HL). The cells were positive for CD2 and CD30 and negative for CD15. The immunoglobulin heavy- and κ light-chain genes were rearranged. The karyotype was of the triploid range. Southern blotting using the EBV terminal repeat probe detected 3 hybridizing bands that were identical to those of the parental HL material. The cells expressed EBV-encoded RNAs as well as latent genes (EBNA1, EBNA2, LMP1, and LMP2A) and lytic genes (BZLF1 and BALF2). Fluorescence in situ hybridization (FISH) with the cosmid pJB8 clone containing a fragment of EBV DNA as a probe revealed multiple hybridization signals at a marker chromosome. Additional FISH using whole chromosome painting and centromere probes in combination with multicolor FISH determined that multiple EBV copies were clustered within the chromosome 20 materials of the marker chromosome. Culture supernatants of AM-HLH contained IL-10 as measured by the bead-based immunoassay. It is possible that an integrated EBV genome and cellular genes on chromosome 20 were coamplified, leading to the enhanced expression of genes involved in cell growth control. The AM-HLH cell line will be useful to clarify the role of cytokines in the development of EBV+ HL.

Platelet-Derived Growth Factor Receptor-α Regulates Proliferation of Gastrointestinal Stromal Tumor Cells With Mutations in KIT by Stabilizing ETV1.

BACKGROUND & AIMS: In gastrointestinal muscles, v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT) is predominantly expressed by interstitial cells of Cajal (ICC) and platelet-derived growth factor receptor-α (PDGFRA) polypeptide is expressed by so-called fibroblast-like cells. KIT and PDGFRA have been reported to be coexpressed in ICC precursors and gastrointestinal stromal tumors (GISTs), which originate from the ICC lineage. PDGFRA signaling has been proposed to stimulate growth of GISTs that express mutant KIT, but the effects and mechanisms of selective blockade of PDGFRA are unclear. We investigated whether inhibiting PDGFRA could reduce proliferation of GIST cells with mutant KIT via effects on the KIT-dependent transcription factor ETV1. METHODS: We studied 53 gastric, small intestinal, rectal, or abdominal GISTs collected immediately after surgery or archived as fixed blocks at the Mayo Clinic and University of California, San Diego. In human GIST cells carrying imatinib-sensitive and imatinib-resistant mutations in KIT, PDGFRA was reduced by RNA interference (knockdown) or inhibited with crenolanib besylate (a selective inhibitor of PDGFRA and PDGFRB). Mouse ICC precursors were retrovirally transduced to overexpress wild-type Kit. Cell proliferation was analyzed by methyltetrazolium, 5-ethynyl-2'-deoxyuridine incorporation, and Ki-67 immunofluorescence assays; we also analyzed growth of xenograft tumors in mice. Gastric ICC and ICC precursors, and their PDGFRA(+) subsets, were analyzed by flow cytometry and immunohistochemistry in wild-type, Kit(+/copGFP), Pdgfra(+/eGFP), and NOD/ShiLtJ mice. Immunoblots were used to quantify protein expression and phosphorylation. RESULTS: KIT and PDGFRA were coexpressed in 3%-5% of mouse ICC, 35%-44% of ICC precursors, and most human GIST samples and cell lines. PDGFRA knockdown or inhibition with crenolanib efficiently reduced proliferation of imatinib-sensitive and imatinib-resistant KIT(+)ETV1(+)PDGFRA(+) GIST cells (50% maximal inhibitory concentration = 5-32 nM), but not of cells lacking KIT, ETV1, or PDGFRA (50% maximal inhibitory concentration >230 nM). Crenolanib inhibited phosphorylation of PDGFRA and PDGFRB, but not KIT. However, Kit overexpression sensitized mouse ICC precursors to crenolanib. ETV1 knockdown reduced KIT expression and GIST proliferation. Crenolanib down-regulated ETV1 by inhibiting extracellular-signal-regulated kinase (ERK)-dependent stabilization of ETV1 protein and also reduced expression of KIT and PDGFRA. CONCLUSIONS: In KIT-mutant GIST, inhibition of PDGFRA disrupts a KIT-ERK-ETV1-KIT signaling loop by inhibiting ERK activation. The PDGFRA inhibitor crenolanib might be used to treat patients with imatinib-resistant, KIT-mutant GIST.

Preoperative Tissue Doppler Imaging-Derived Atrial Conduction Time Predicts Postoperative Atrial Fibrillation in Patients Undergoing Mitral Valve Surgery for Mitral Valve Regurgitation.

BACKGROUND: Postoperative atrial fibrillation (POAF) is a common complication of cardiac surgery and may result in stroke, heart failure and poor prognosis. This study evaluated a novel index of total atrial conduction time derived from the P-wave onset (lead II) to the peak A' wave on tissue Doppler imaging (PA-TDI duration) in patients undergoing mitral valve surgery (MVS) for mitral valve regurgitation. METHODS AND RESULTS: Seventy-three patients undergoing MVS had transthoracic echocardiography with tissue Doppler imaging preoperatively and were monitored postoperatively with continuous electrocardiographic telemetry for 14 days. Preoperative characteristics, echocardiographic data, operative data and postoperative findings were compared between patients with (n=44) and without (n=29) POAF. Postoperative cardiac events were higher in patients with than without POAF (12/44, 27% vs. 3/29, 10%; P=0.0798) and cerebral events occurred in only 2 POAF patients. On multivariate analysis the independent predictors of POAF were degenerative disease etiology (OR, 4.61; 95% CI: 1.41-15.0; P=0.0112) and PA-TDI duration (OR, 1.04; 95% CI: 1.01-1.07; P=0.0048). On ROC curve analysis a PA-TDI cut-off of 159.4 ms was optimal for predicting POAF. CONCLUSIONS: PA-TDI duration was an independent predictor of POAF after MVS. Patients with PA-TDI duration >159.4 ms should be considered high risk and treated appropriately to improve outcome.

Iliac Artery Stenting Combined with Open Iliofemoral Endarterectomy Facilitated by a Novel Ultrasonic Ablation Instrument for Diffuse Iliofemoral Occlusive Disease.

An 81-year-old male complained of intermittent claudication of the right leg. Computed tomography (CT) revealed a right external iliac artery (EIA) stenosis with severe calcification extending to the common femoral artery. A hybrid procedure of endarterectomy and stenting was performed. EIA endarterectomy was performed using a novel Cavitron Ultrasonic Surgical Aspirator which ablated the inside of the distal EIA without arterial injury. A stent graft was placed in the proximal EIA covering the margin of endarterectomized distal EIA. Postoperative CT showed no stenosis, and symptoms in the leg disappeared. This could be an alternative procedure for iliofemoral occlusive disease.

Mitral Valve Replacement via Anterolateral Right Thoracotomy without Cross-Clamping in a Patient with Fungal Infective Endocarditis and Functioning Internal Mammary Artery after Previous Coronary Artery Bypass Grafting and Mitral Valve Repair.

A 55-year-old man developed severe mitral regurgitation with persistent fungal infective endocarditis 8 months after coronary artery bypass grafting with a left internal mammary artery and 2 saphenous veins, as well as mitral valve repair with a prosthetic ring. Echocardiography demonstrated severe mitral regurgitation and a valvular vegetation. Computed tomography coronary arteriography indicated that all grafts were patent and located intimately close to the sternum. Median resternotomy was not attempted due to the risk of injury to the bypass grafts, and therefore, a right anterolateral thoracotomy approach was utilized. Mitral valve replacement was performed with the patient under deep hypothermia and ventricular fibrillation without aortic cross-clamping. The patient`s postoperative course was uneventful. Thus, right anterolateral thoracotomy may be a superior approach to mitral valve surgery in patients who have undergone prior coronary artery bypass grafting.

Lysosomal Sequestration Determines Intracellular Imatinib Levels.

The intracellular uptake and retention (IUR) of imatinib is reported to be controlled by the influx transporter SLC22A1 (organic cation transporter 1). We recently hypothesized that alternative uptake and/or retention mechanisms exist that determine intracellular imatinib levels. Here, we systematically investigate the nature of these mechanisms. Imatinib uptake in cells was quantitatively determined by liquid chromatography-tandem mass spectrometry. Fluorescent microscopy was used to establish subcellular localization of imatinib. Immunoblotting, cell cycle analyses, and apoptosis assays were performed to evaluate functional consequences of imatinib sequestration. Uptake experiments revealed high intracellular imatinib concentrations in HEK293, the leukemic cell lines K562 and SD-1, and a gastrointestinal stromal tumor cell line GIST-T1. We demonstrated that imatinib IUR is time-, dose-, temperature-, and energy-dependent and provide evidence that SLC22A1 and other potential imatinib transporters do not substantially contribute to the IUR of imatinib. Prazosin, amantadine, NH4Cl, and the vacuolar ATPase inhibitor bafilomycin A1 significantly decreased the IUR of imatinib and likely interfere with lysosomal retention and accumulation of imatinib. Costaining experiments with LysoTracker Red confirmed lysosomal sequestration of imatinib. Inhibition of the lysosomal sequestration had no effect on the inhibition of c-Kit signaling and imatinib-mediated cell cycle arrest but significantly increased apoptosis in imatinib-sensitive GIST-T1 cells. We conclude that intracellular imatinib levels are primarily determined by lysosomal sequestration and do not depend on SLC22A1 expression.

Prognostic significance of promyelocytic leukemia expression in gastrointestinal stromal tumor; integrated proteomic and transcriptomic analysis.

Prognostic markers are urgently needed to optimize the postoperative treatment strategies for gastrointestinal stromal tumors (GIST). GIST of the small intestine (I-GIST) show more aggressive behavior than those of the stomach (S-GIST), and the molecular background of the malignancy in I-GIST may include potential prognostic biomarkers. We conducted integrated proteomic and transcriptomic analysis to identify genes showing differential expressions according to the tumor site. We generated protein expression profiles for four cases each of surgically resected I-GIST and S-GIST using label-free proteomic analysis. For proteins showing differential expressions, global mRNA expression was compared between 9 I-GIST and 23 S-GIST. Among the 2555 genes analyzed, we found that promyelocytic leukemia (PML), a tumor suppressor gene, was significantly downregulated in I-GIST at both the protein and mRNA levels (P < 0.01; fold difference ≥2.0). Immunohistochemistry of 254 additional cases from multiple clinical facilities showed that PML-negative cases were significantly frequent in the I-GIST group (P < 0.001). The 5-year recurrence-free survival rate was significantly lower in the PML-negative than in the PML-positive cases (60.1% vs 91.7%; P < 0.001). Multivariate analysis revealed that downregulation of PML was an independent unfavorable prognostic factor (hazard ratio = 2.739; P = 0.001). Our study indicated that prognostication based on PML expression may have potential for optimizing the treatment strategy for GIST patients. Further validation studies of PML for clinical application, and investigation for the mechanistic significance of PML to clarify the molecular backgrounds of malignancy in GIST are warranted.

Efficacy of cardiopulmonary rehabilitation with adaptive servo-ventilation in patients undergoing off-pump coronary artery bypass grafting.

BACKGROUND: Postoperative complications after cardiac surgery increase mortality. This study aimed to evaluate the efficacy of cardiopulmonary rehabilitation with adaptive servo-ventilation (ASV) in patients undergoing off-pump coronary artery bypass grafting (OPCAB). METHODS AND RESULTS: A total of 66 patients undergoing OPCAB were enrolled and divided into 2 groups according to the use of ASV (ASV group, 30 patients; non-ASV group, 36 patients). During the perioperative period, all patients undertook cardiopulmonary rehabilitation. ASV was used from postoperative day (POD) 1 to POD5. Hemodynamics showed a different pattern in the 2 groups. Blood pressure (BP) on POD6 in the ASV group was significantly lower than that in the non-ASV group (systolic BP, 112.9±12.6 vs. 126.2±15.8 mmHg, P=0.0006; diastolic BP, 62.3±9.1 vs. 67.6±9.3 mmHg, P=0.0277). The incidence of postoperative atrial fibrillation (POAF) was lower in the ASV group than in the non-ASV group (10% vs. 33%, P=0.0377). The duration of oxygen inhalation in the ASV group was significantly shorter than that in the non-ASV group (5.1±2.2 vs. 7.6±6.0 days, P=0.0238). The duration of postoperative hospitalization was significantly shorter in the ASV group than in the non-ASV group (23.5±6.6 vs. 29.0±13.1 days, P=0.0392). CONCLUSIONS: Cardiopulmonary rehabilitation with ASV after OPCAB reduces both POAF occurrence and the duration of hospitalization.

Inactivation of Patched1 in mice leads to development of gastrointestinal stromal-like tumors that express Pdgfrα but not kit.

BACKGROUND & AIMS: A fraction of gastrointestinal stromal tumor (GIST) cells overexpress the platelet-derived growth factor receptor (PDGFR)A, although most overexpress KIT. It is not known if this is because these receptor tyrosine kinases have complementary oncogenic potential, or because of heterogeneity in the cellular origin of GIST. Little also is known about why Hedgehog (HH) signaling is activated in some GIST. HH binds to and inactivates the receptor protein patched homolog (PTCH). METHODS: Ptch was conditionally inactivated in mice (to achieve constitutive HH signaling) using a Cre recombinase regulated by the lysozyme M promoter. Cre-expressing cells were traced using R26R-LacZ reporter mice. Tumors were characterized by in situ hybridization, immunohistochemistry, immunoblot, and quantitative reverse-transcriptase polymerase chain reaction analyses. Cell transformation was assessed by soft agar assay. RESULTS: Loss of Ptch from lysozyme M-expressing cells resulted in the development of tumors of GIST-like localization and histology; these were reduced when mice were given imatinib, a drug that targets KIT and PDGFRA. The Hh signaling pathway was activated in the tumor cells, and Pdgfrα, but not Kit, was overexpressed and activated. Lineage tracing revealed that Cre-expressing intestinal cells were Kit-negative. These cells sometimes expressed Pdgfrα and were located near Kit-positive interstitial cells of Cajal. In contrast to KIT, activation of PDGFRA increased anchorage-independent proliferation and was required for tumor formation in mice by cells with activated HH signaling. CONCLUSIONS: Inactivation of Ptch in mice leads to formation of GIST-like tumors that express Pdgfrα, but not Kit. Activation of Pdgfrα signaling appears to facilitate tumorigenesis.

Preoperative tissue Doppler imaging-derived atrial conduction time can predict postoperative atrial fibrillation in patients undergoing aortic valve replacement for aortic valve stenosis.

BACKGROUND: Postoperative atrial fibrillation (POAF) is a common complication of cardiac surgery and may result in stroke or heart failure and poor prognosis. This study aimed to evaluate a novel index of total atrial conduction time derived from the P-wave onset (lead II) to the peak A' wave on tissue Doppler imaging (PA-TDI duration). The PA-TDI duration was compared with previously reported predictors of POAF, and the optimal cutoff value of PA-DTI was calculated in patients undergoing aortic valve replacement (AVR) for AV stenosis (AS). METHODS AND RESULTS: We enrolled 63 patients undergoing isolated AVR. They underwent transthoracic echocardiography with TDI preoperatively and were monitored postoperatively with continuous electrocardiographic telemetry for 7 days. The hospital stay was significantly longer in the 41 patients with POAF than in the 22 without POAF (33.8±19.7 vs. 24.1±8.1 days, P=0.03). Multivariate analysis revealed that PA-TDI duration (odds ratio [OR], 1.07; 95% confidence interval [CI], 1.02-1.13; P=0.0072) and age (OR, 1.14; CI, 1.03-1.28; P=0.016) were significant independent predictors of POAF. Receiver-operating characteristic curve analysis showed the optimal cutoff values of PA-TDI duration and age were 147.3 ms and 74 years, respectively. CONCLUSIONS: The PA-TDI duration was an independent predictor of POAF after AVR for AS. Patients with PA-TDI duration >147 ms should be considered high risk and treated appropriately to improve outcomes.

Molecular cytogenetic analysis of the scleractinian coral Acropora solitaryensis Veron & Wallace 1984.

We performed a molecular cytogenetic investigation of the scleractinian coral Acropora solitaryensis, which is dominant in the temperate region of Japan (30-35°N). Molecular cytogenetic analysis, using fluorescence in situ hybridization (FISH), was carried out for karyotyping and gene mapping. We propose the karyotype of this coral (2n = 30) based on C-banding and FISH analyses. FISH mapping of the rRNA gene was carried out with a probe generated by PCR amplification using rRNA gene primers. Furthermore, the telomeres and centromeres of all chromosomes were visualized using FISH. By comparative genomic hybridization using DNA from sperm and unfertilized eggs of this coral, we offer evidence suggesting the existence of sex chromosomes in this species. Collectively, these data advance our understanding of coral genetics.

Peridinin from the marine symbiotic dinoflagellate, Symbiodinium sp., regulates eosinophilia in mice.

Peridinin and fucoxanthin, which are natural carotenoids isolated from a symbiotic dinoflagellate, Symbiodinium sp., and a brown alga, Petalonia fascia, respectively, were compared for inhibitory effects on delayed-type hypersensitivity in mice. The number of eosinophils at the site of inflammation and in peripheral blood was compared for the administration of peridinin and fucoxanthin applied by painting and intraperitoneally. Peridinin, but not the structurally-related fucoxanthin, significantly suppressed the number of eosinophils in both the ear lobe and peripheral blood. Furthermore, peridinin applied topically, but not administered intraperitoneally, suppressed the level of eotaxin in the ears of sensitized mice. Fucoxanthin weakly suppressed the concentration of eotaxin in ears only by intraperitoneal administration. Although both carotenoids inhibited the migration of eosinophils toward eotaxin, the inhibitory effect of peridinin was higher than that of fucoxanthin. Peridinin may be a potential agent for suppressing allergic inflammatory responses, such as atopic dermatitis, in which eosinophils play a major role in the increase of inflammation.

Prevention of pacemaker-associated contact dermatitis by polytetrafluoroethylene sheet and conduit coating of the pacemaker system.

A 73-year-old female with sick sinus syndrome and atrial fibrillation was implanted with a ventricular demand inhibit pacemaker. She subsequently developed multiple episodes of skin irritation and necrosis. Skin patch testing revealed sensitivity to almost every component of the pacemaker system. The pacemaker was removed and replaced with a new pacemaker in which the generator was covered with a polytetrafluoroethylene (PTFE) sheet and the lead was covered with PTFE conduit. The patient suffered no further episodes of pacemaker-associated contact dermatitis.

Modified septal myectomy using a curved knife for left ventricular septal hypertrophy.

An 86-year-old woman presented with chest pain and discomfort. Echocardiography revealed severe aortic valve stenosis and asymmetric septal hypertrophy. Aortic valve replacement and myectomy were performed using a curved knife. The blade was U-shaped in cross-section, and was curved upward along the long axis. Hypertrophic septal myocardium was removed along the long axis of the left ventricle (LV), and a groove for blood flow was constructed. The patient was discharged uneventfully without recurrence of her chest discomfort. Our result suggested that a curved knife is a reasonable option for transaortic septal myectomy in patients with obstructive LV hypertrophy.

A case of Heyde syndrome: resolution following aortic valve replacement.

Heyde syndrome is a triad of aortic stenosis, acquired coagulopathy, and anemia due to bleeding from intestinal angiodysplasia. Here we describe a case of this syndrome. An 80-year-old woman with severe aortic stenosis was referred to our department for an aortic valve replacement. She suffered from recurrent iron-deficiency anemia and required transfusions every 2 weeks. Gastroscopy and colonoscopy were normal with the exception of angiodysplasia without bleeding in the cecum. After aortic valve replacement her anemia was resolved. She was discharged on postoperative day 22. No transfusions were needed after the procedure. To date, her hemoglobin has remained stable at >10 mg/dL.

Spatiotemporal patterns of throwing muscle synergies in yips-affected baseball players.

"Yips" are involuntary movements that interfere with the automatic execution of sports movements. However, how the coordination among the various muscles necessary for sports movements is impaired in athletes with yips remains to be fully understood. This study aimed to assess whether muscle synergy analysis through non-negative matrix factorization (NMF) could identify impaired spatiotemporal muscle coordination in baseball players with throwing yips. Twenty-two college baseball players, including 12 with and 10 without yips symptoms participated in the study. Electromyographic activity was recorded from 13 ipsilateral upper extremity muscles during full-effort throwing. Muscle synergies were extracted through NMF. Cluster analysis was conducted to identify any common spatiotemporal patterns of muscle synergies in players with yips. Whether individual players with yips showed deviations in spatiotemporal patterns of muscle synergies compared with control players was also investigated. Four muscle synergies were extracted for each player, but none were specific to the yips group. However, a more detailed analysis of individual players revealed that two of the three players who presented dystonic symptoms during the experiment exhibited specific patterns that differed from those in control players. By contrast, each player whose symptoms were not reproduced during the experiment presented spatiotemporal patterns of muscle synergies similar to those of the control group. The results of this study indicate no common spatiotemporal pattern of muscle synergies specific to the yips group. Furthermore, these results suggest that the spatiotemporal pattern of muscle synergies in baseball throwing motion is not impaired in situations where symptoms are not reproduced even if the players have yips symptoms. However, muscle synergy analysis can identify the characteristics of muscle coordination of players who exhibit dystonic movements. These findings can be useful in developing personalized therapeutic strategies based on individual characteristics of yips symptoms.

New findings of kinase switching in gastrointestinal stromal tumor under imatinib using phosphoproteomic analysis.

Despite the revolutionary effects of imatinib on advanced gastrointestinal stromal tumors (GISTs), most patients eventually develop disease progression following primary resistance or acquired resistance driven by secondary-resistant mutations. Even in radiographically vanishing lesions, pathology has revealed persistent viable cells during imatinib therapy, which could lead to the emergence of drug-resistant clones. To uncover the mechanisms underlying these clinical issues, here we examined imatinib-induced phosphoproteomic alterations in GIST-T1 cells, using our quantitative tyrosine phosphoproteomic analysis method, which combined immunoaffinity enrichment of phosphotyrosine-containing peptides with isobaric tags for relative and absolute quantitation (iTRAQ) technology. Using this approach, we identified 171 tyrosine phosphorylation sites spanning 134 proteins, with 11 proteins exhibiting greater than 1.5-fold increases in tyrosine phosphorylation. Among them, we evaluated FYN and focal adhesion kinase (FAK), both of which are reportedly involved in proliferation and malignant alteration of tumors. We confirmed increased tyrosine phosphorylation of both kinases by western blotting. Inhibition of FYN and FAK phosphorylation each increased tumor cell sensitivity to imatinib. Furthermore, a FAK-selective inhibitor (TAG372) induced apoptosis of imatinib-resistant GIST-T1 cells and decreased the imatinib IC50 . These results indicate that FYN or FAK might be potential therapeutic targets to overcome resistance to imatinib in GISTs. Additionally, we showed that the iTRAQ-based quantitative phosphotyrosine-focused phosphoproteomic approach is a powerful method for screening phosphoproteins associated with drug resistance.

Regulatory effects of Spirulina complex polysaccharides on growth of murine RSV-M glioma cells through Toll-like receptor 4.

This study is the first to report that Spirulina complex polysaccharides (CPS) suppress glioma growth by down-regulating angiogenesis via a Toll-like receptor 4 signal. Murine RSV-M glioma cells were implanted s.c. into C3H/HeN mice and TLR4 mutant C3H/HeJ mice. Treatment with either Spirulina CPS or Escherichia coli (E. coli) lipopolysaccharides (LPS) strongly suppressed RSV-M glioma cell growth in C3H/HeN, but not C3H/HeJ, mice. Glioma cells stimulated production of interleukin (IL)-17 in both C3H/HeN and C3H/HeJ tumor-bearing mice. Treatment with E. coli LPS induced much greater IL-17 production in tumor-bearing C3H/HeN mice than in tumor-bearing C3H/HeJ mice. In C3H/HeN mice, treatment with Spirulina CPS suppressed growth of re-transplanted glioma; however, treatment with E. coli LPS did not, suggesting that Spirulina CPS enhance the immune response. Administration of anti-cluster of differentiation (CD)8, anti-CD4, anti-CD8 antibodies, and anti-asialo GM1 antibodies enhanced tumor growth, suggesting that T cells and natural killer cells or macrophages are involved in suppression of tumor growth by Spirulina CPS. Although anti-interferon-γ antibodies had no effect on glioma cell growth, anti-IL-17 antibodies administered four days after tumor transplantation suppressed growth similarly to treatment with Spirulina CPS. Less angiogenesis was observed in gliomas from Spirulina CPS-treated mice than in those from saline- or E. coli LPS-treated mice. These findings suggest that, in C3H/HeN mice, Spirulina CPS antagonize glioma cell growth by down-regulating angiogenesis, and that this down-regulation is mediated in part by regulating IL-17 production.

Autophagy inhibition and antimalarials promote cell death in gastrointestinal stromal tumor (GIST).

Although gastrointestinal stromal tumors (GISTs) harboring activating KIT or platelet-derived growth factor receptor A (PDGFRA) mutations respond to treatment with targeted KIT/PDGFRA inhibitors such as imatinib mesylate, these treatments are rarely curative. Most often, a sizeable tumor cell subpopulation survives and remains quiescent for years, eventually resulting in acquired resistance and treatment failure. Here, we report that imatinib induces autophagy as a survival pathway in quiescent GIST cells. Inhibiting autophagy, using RNAi-mediated silencing of autophagy regulators (ATGs) or antimalarial lysosomotrophic agents, promotes the death of GIST cells both in vitro and in vivo. Thus, combining imatinib with autophagy inhibition represents a potentially valuable strategy to promote GIST cytotoxicity and to diminish both cellular quiescence and acquired resistance in GIST patients.