Cancer stem cells niche: A target for novel cancer therapeutics

Nowadays, cancer has been a frequent disease, and the first or second most common cause of death worldwide. Despite a better understanding of the biology of cancer cells, the therapy of most cancers has not significantly changed for the past four decades. It is because conventional chemotherapies and/or radiation therapies are usually designed to eradicate highly proliferative cells. Mounting evidence has implicated that cancer is a disease of stem cells. Cancer stem cells (CSC) are often relatively quiescent, and therefore may not be affected by therapies targeting rapidly dividing cells. Like normal stem cells (NSC) residing in a “stem cell niche” that maintains them in a stem-like state, CSC also require a special microenvironment to control their self-renewal and undifferentiated state. The “CSC niche” is likely to be the most crucial target in the treatment of cancer. In this article, we summarize the current knowledge regarding CSC and their niche microenvironments. Understanding of CSC’s origin, molecular profile, and interaction with their microenvironments, this could be a paradigm shift in the treatment of cancer, away from targeting the blast cells and towards the targeting of the CSC, thus improving therapeutic outcome.     

Therapeutic options for recurrent malignant glioma

Background and purpose: Despite the given advances in neuro-oncology most patients with high grade malignant glioma ultimately fail locally or locoregionally. In parallel with improvements of initial treatment options, several salvage strategies have been elucidated and already entered clinical practice. Aim of this article is to review the current status of salvage strategies in recurrent high grade glioma. Material and methods: Using the following MESH headings and combinations of these terms the pubmed database was searched: “Glioma”, “Recurrence”, “Neoplasm Recurrence, Local”, “Radiosurgery”, “Brachytherapy”, “Neurosurgical Procedures” and “Drug Therapy”. For citation crosscheck the ISI web of science database was used employing the same search terms. In parallel, the abstracts of ASCO 2008-2009 were analyzed accordingly. Results: Currently the following options for salvage entered clinical practice: re-resection, re-irradiation (stereotactic radiosurgery, (hypo-)fractionated (stereotactic) radiotherapy, interstitial brachytherapy) or single/poly-chemotherapy schedules including new dose-intensified or alternative treatment protocols employing targeted drugs. Re-operation is associated with high morbidity and mortality, however, is an option in a highly selected patient cohort. Since toxicity has been overestimated, re-irradiation is an increasingly used option with precise fractionated radiotherapy being the most optimal technique. On average, time to secondary progression is in the range of several months. Conventional chemotherapy regimens also improve time to secondary progression; however the efficacy is only modest and treatment-related toxicities like myelo-suppression occur very frequently. Molecular targeted agents/kinases are undergoing clinical testing; however no final recommendations can be made. Conclusions: Currently, several re-treatment options with only modest efficacy exist. The relative value of each approach compared to other options is unknown as well as it remains open which sequence of modalities should be chosen.     

Perivascular stem cell niche in head and neck cancer

Cancers may contain a small sub-population of uniquely tumorigenic cells that exhibit self-renewal and multipotency, i.e. cancer stem cells (CSCs). These cells reside in invasive fronts in close proximity to blood vessels in many tumors, including head and neck squamous cell carcinomas (HNSCCs). Recent evidence suggests that CSC resist chemotherapy and “drive” local recurrence and metastatic spread. Notably, endothelial cell-initiated signaling is critical for the survival and self-renewal of CSC and may play a role in resistance to therapy. Therefore, patients with head and neck cancer might benefit from therapies that target the CSC directly or their supportive perivascular niche.     

Genomic instability in myeloid malignancies: Increased reactive oxygen species (ROS), DNA double strand breaks (DSBs) and error-prone repair

Disease progression in myeloid malignancies results from the accumulation of “mutations” in genes that control cellular growth and differentiation. Many types of genetic alterations have been identified in myeloid diseases. However, the mechanism(s) by which these cells acquire genetic alterations or “Genomic instability”, is less well understood. Increasing evidence suggests that the genetic changes in myeloid malignancies lead to increased production of endogenous sources of DNA damage, such as, reactive oxygen species (ROS). The fusion gene BCR–ABL in chronic myeloid leukemia (CML), FLT3/ITD in acute myeloid leukemia (AML), and RAS mutations in myelodysplastic syndromes (MDS)/myeloproliferative diseases (MPD) result in ROS production. Increased ROS can drive a cycle of genomic instability leading to DNA double strand breaks (DSBs) and altered repair that can lead to acquisition of genomic changes. Evidence is coming to light that defects in a main repair pathway for DSBs, non-homologous end-joining (NHEJ), lead to up-regulation of alternative or “back-up” repair that can create chromosomal deletions and translocations. This article will review evidence for activation of RAS/PI3K/STAT pathways, that lead to increased ROS, DNA damage and defective repair in myeloid diseases, a mechanism for acquisition of additional mutations that can drive disease progression.     

Serum discrimination of early-stage lung cancer patients using electrospray-ionization mass spectrometry

The goal of this study was to evaluate the usefulness of electrospray ionization-mass spectrometry (ESI-MS) technology to distinguish sera of early-stage lung cancer patients from control individuals. ESI-MS m/z (mass divided by charge) data were generated from sera of 43 non-small cell lung cancer patients (pathological stages I and II) and 21 control individuals. Identifications of m/z peak area significances between cancer and control ESI-MS sera spectra were performed using t-tests. A “leave one out” cross validation procedure, which mimics blinded sera analysis and corrects for “over-fitting” of data, yielded discriminatory cancer versus control distribution p value and ROC curve area value of <0.001 and 0.87, respectively. Analysis without the “leave one out” cross validation procedure yielded a ROC curve area of 0.99 for discrimination of sera from lung cancer patients versus control individuals. Predictive value measurements revealed overall test efficiency and sensitivity for distinguishing sera from lung cancer patients from controls (using “leave one out” cross validation) of 80% and 84%, respectively. ESI-MS serum analysis between control individuals and lung cancer patients who smoked or did not smoke had p values in ranges indicating that smoking effects are not pronounced in our analysis. These studies indicate that ESI-MS analyses of sera from early stage non-small cell lung cancer patients were helpful in distinguishing these patients from control individuals.     

The clinical significance of cytology versus histology-based diagnosis in small cell lung cancer: A retrospective study

Objectives

The aim of this study was to investigate the clinical significance of cytology versus histology-based diagnosis among patients diagnosed with small cell lung cancer (SCLC).

Materials and methods

Retrospective analysis of medical records of 443 patients with histologically or cytologically confirmed small cell lung carcinoma (SCLC) was performed. All patients received platinum-based chemotherapy regimens. Survival data (overall survival) were compared between patients with histology or cytology-based diagnosis in the overall study population as well as after stratification of patients according to disease stage (limited or extensive) at the time of diagnosis.

Results

Distribution of demographics and clinicopathological characteristics among the two groups (“histology” and “cytology”) was similar. No statistically significant differences in the survival curves between the “histology” and “cytology” groups were found in the overall study population (log rank test, p = 0.237), as well as in the subgroup of patients with limited disease (log rank test, p = 0.474). In contrast, patients with histology-based diagnosis had a statistically significant longer survival as compared to those with cytology-based diagnosis in the extensive disease subgroup (log rank test, p = 0.031), but this association was not retained after adjusting the analysis for demographics and clinical characteristics via a Cox regression model (HR = 1.18, 95% CI: 0.96–1.44, p = 0.110).

Conclusion

The results of our study suggest that the type of diagnostic modality employed (histology or cytology-based) for the establishment of a diagnosis of SCLC may not have a significant effect on the overall survival of patients. Further studies are warranted to further investigate this important, yet rather unexplored, issue.     

Overcoming cetuximab resistance in HNSCC: The role of AURKB and DUSP proteins

Unraveling the underlying mechanisms of cetuximab resistance in head and neck squamous cell carcinoma (HNSCC) is of major importance as many tumors remain non-responsive or become resistant. Our microarray results suggest that “resistant” cells still exhibit RAS–MAPK pathway signaling contributing to drug resistance, as witnessed by low expression of DUSP5 and DUSP6, negative regulators of ERK1/2, and increased expression of AURKB, a key regulator of mitosis. Therefore, interrupting the RAS–MAPK pathway by an ERK1/2 inhibitor (apigenin) or an AURKB inhibitor (barasertib) might be a new strategy for overcoming cetuximab resistance in HNSCC.     

Migration of intraprostatic fiducial markers and its influence on the matching quality in external beam radiation therapy for prostate cancer

Purpose

To assess the influence of fiducial marker (FM) migration on the matching quality in external beam radiation therapy (EBRT) for prostate cancer.

Materials and methods

The position of FMs were identified using on-board kV imaging (OBI) and their 3-D position established using an in-house reconstruction algorithm for 31 patients with prostate adenocarcinoma. To carry out the match, the positions were overlaid on the digitally reconstructed radiographs (DRR) generated from the planning CT. The distance between each FM was calculated for seven treatments throughout the EBRT course. Four radiotherapy technologists were asked to independently perform and rate the match from OBI to DRR which was then correlated to the extent of FM migration.

Results

All the matches were rated by at least three radiotherapy technologists as “very easy” (“easy” subgroup) for 24 patients (77%), while the other seven patients had their match rated less than “very easy” and considered the “not easy” subgroup. The average daily FM migration was 0.93 ± 0.34 mm for the “easy” subgroup vs. 1.82 ± 0.75 mm for the latter. An average migration >2 mm was seen in five/seven patients in the “not easy” subgroup as compared to none in the “easy” subgroup. There was a trend towards less FM migration and better matching if the planning CT was done later than the day of the FM implant (p = 0.093).

Conclusions

FM migration >2 mm predicts for a more difficult matching process; PTV margins might have to be adjusted or the planning CT repeated.     

Early prediction of response by F-FDG PET/CT during preoperative therapy in locally advanced rectal cancer: A systematic review

Aim

To assess the predictive value of fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in early assessing response during neo-adjuvant chemoradiotherapy (CRT) in patients with locally advanced rectal cancer.

Materials and methods

A systematic review was performed by search of MEDLINE Library for the following terms: “rectal carcinoma OR rectal cancer”, “predictive OR prediction OR response assessment OR response OR assessment”, “early OR ad interim”, “therapy”, “FDG OR ¹⁸F-FDG”, “PET OR PET/CT”. Articles performed by the use of stand-alone PET scanners were excluded.

Results

10 studies met the inclusion criteria, including 302 patients. PET/CT demonstrated a good early predictive value in the global cohort (mean sensitivity = 79%; mean specificity = 78%). SUV and its percentage decrease (response index = RI) were calculated in all studies. A higher accuracy was demonstrated for RI (mean sensitivity = 82%; pooled specificity = 85%) with a mean cut-off of 42%. The mean time point to perform PET scan during CRT resulted to be at 1.85 weeks. Some PET parameters resulted to be both predictive and not statistical predictive of response, maybe due to the small population and few studies bias.

Conclusion

PET showed high accuracy in early prediction response during preoperative CRT, increased with the use of RI as parameter. In the era of tailored treatment, the precocious assessment of non-responder patients allows modification of the subsequent strategy especially the timing and the type of surgical approach.     

Contouring of the Pharyngeal Superior Constrictor Muscle (PSCM). A cooperative study of the Italian Association of Radiation Oncology (AIRO) Head and Neck Group

Background and purpose

Irradiation of the Pharyngeal Superior Constrictor Muscle (PSCM) seems to play a crucial role in radiation-related swallowing dysfunctions. Purpose of our study was to quantify operator-related variability in the contouring of PSCM on Computed Tomography (CT) scans and adherence with contours derived from MR images.

Materials and methods

Three sets of treatment planning CT and their corresponding MR images were selected. Contouring of the PSCM was performed using both a literature-based method, derived from literature review, and an optimized method, derived from Magnetic Resonance (MR) images thus obtaining “literature-based” and “optimized” contours. Each operator contoured the PSCM on CT scans according to both methods for three times in three different days. Inter- and intra-operator variability and adherence to a contour obtained from MR images (named “MR-derived” contour) were analyzed.

Results

Thirty-four operators participated and 612 contours were obtained. Both intra- and inter-operator variability and adherence to the “MR-derived” contour were significantly different between the two methods (p ? 0.05). The “optimized” method showed a lower intra- and inter-operator variability and a higher adherence to the “MR-derived” contour.

Conclusions

The “optimized” method ameliorates both operator-related variability and adherence with MR images.     

Re-appraisal of N2 disease by lymphatic drainage pattern for non-small-cell lung cancers: by terms of nodal stations, zones, chains, and a composite

Purpose

N2 non-small-cell lung cancer (NSCLC) is a heterogeneous disease with an extremely wide range of 5-year survival rates. A composite method of sub-classification for N2 is likely to provide a more accurate method to more finely differentiate prognosis of N2 disease.

Methods

A total of 720 pN2 (T1-4N2M0) NSCLC cases were enrolled in our retrospective analysis of the proposed composite method. Survival rates were respectively calculated according to the N2 stratification methods: singly by “nodal stations”, “nodal zones”, or “nodal chains”, or by combination of all three. Statistical analysis was carried out by Kaplan-Meier and Cox regression models.

Results

A total of 10,199 lymph nodes (8059 mediastinal; 2140 hilar and intra-lobar) were removed. By nodal station, there were 173 cases of single-station involvement and 547 multi-stations. By nodal zone, there were 413 single-zone involvement and 307 with multiple zones. By nodal chain, there were 311 cases with single-chain and 409 multi-chain involvements. The overall 5-year survival was 20% and median survival time was 27.52 months. The 5-year survival was significantly better for cases of single-zone involvement, as compared to multi-zones (29% vs. 6%, p < 0.0001). The 5-year survival rates of single- and multi-chains involvement were 36% and 8%, respectively (p < 0.0001). When taking all of the above grouping methods into consideration, the N2 disease state could be further sub-classified into two subgroups with respective survival rates of 36% and 7% (p < 0.0001). Subgroup I was composed of individuals with single-chain involvement and having either one or two station metastasis; individuals with any other metastasis combinations formed Subgroup II. Multivariate analysis revealed that the composite sub-classification method, number of positive lymph nodes, ratio of nodal metastasis, and pT information were the most important risk factors of 5-year survival.

Conclusions

By combining the three N2 stratification methods based on “stations”, “zones”, and “chains” into one composite method, prognosis prediction was more accurate for N2 NSCLC disease. Single nodal chain involvement, which may be either one or two nodal stations metastasis, is associated with best outcome for pN2 patients.     

Holy Basil leaf extract decreases tumorigenicity and metastasis of aggressive human pancreatic cancer cells in vitro and in vivo: Potential role in therapy

There is an urgent need to develop alternative therapies against lethal pancreatic cancer (PC). Ocimum sanctum (“Holy Basil”) has been used for thousands of years in traditional Indian medicine, but its anti-tumorigenic effect remains largely unexplored. Here, we show that extracts of O. sanctum leaves inhibit the proliferation, migration, invasion, and induce apoptosis of PC cells in vitro. The expression of genes that promote the proliferation, migration and invasion of PC cells including activated ERK-1/2, FAK, and p65 (subunit of NF-κB), was downregulated in PC cells after O. sanctum treatment. Intraperitoneal injections of the aqueous extract significantly inhibited the growth of orthotopically transplanted PC cells in vivo (p < 0.05). Genes that inhibit metastasis (E-cadherin) and induce apoptosis (BAD) were significantly upregulated in tumors isolated from mice treated with O. sanctum extracts, while genes that promote survival (Bcl-2 and Bcl-xL) and chemo/radiation resistance (AURKA, Chk1 and Survivin) were downregulated. Overall, our study suggests that leaves of O. sanctum could be a potential source of novel anticancer compounds in the future.     

Potential use of imatinib in Ewing's Sarcoma: evidence for in vitro and in vivo activity

BACKGROUND: Ewing's sarcoma cells express c-kit, a receptor tyrosine kinase, and its ligand, stem cell factor (SCF), creating a potential autocrine loop that may promote tumor survival. We thus examined whether the specific tyrosine kinase inhibitor imatinib mesylate (hereafter imatinib; formerly STI571) could inhibit the proliferation of Ewing's sarcoma cells in vitro and in vivo. METHODS: The effect of imatinib on c-kit expression and phosphorylation in Ewing's sarcoma cells was examined by immunoblotting. The effect of imatinib on cell growth and apoptosis was examined with an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay and with a morphologic test and Annexin V staining, respectively. The effect of imatinib oral therapy (every 12 hours for 5-7 days) on primary tumor growth was assessed in Ewing's sarcoma xenografts in SCID/bg mice (5 or 10 mice per group). RESULTS: All Ewing's sarcoma cell lines tested were sensitive to imatinib-mediated apoptosis with a concentration inhibiting growth by 50% (IC50) of 10-12 micro M. Imatinib inhibited SCF-mediated c-kit phosphorylation (IC50 = 0.1-0.5 microM). In the xenograft model, imatinib treatment resulted in the regression or control of primary Ewing's sarcomas. After 6 days of treatment, the mean lower extremity volume including xenograft tumor was 3744 mm3 (95% confidence interval [CI] = 3050 to 4437 mm3), 1442 mm3 (95% CI = 931 to 1758 mm3), and 346 mm3 (95% CI = 131 to 622 mm3) in mice treated with carrier alone or with imatinib at 50 mg/kg or at 100 mg/kg, respectively. CONCLUSIONS: Imatinib interferes with growth of all Ewing's sarcoma cell lines tested in vitro and in vivo. Targeted inhibition of tyrosine kinase-dependent autocrine loops, therefore, may be a viable therapeutic strategy for Ewing's sarcoma.     

Hypoxia-activated chemotherapeutic TH-302 enhances the effects of VEGF-A inhibition and radiation on sarcomas

Background:

Human sarcomas with a poor response to vascular endothelial growth factor-A (VEGF-A) inhibition and radiation therapy (RT) have upregulation of hypoxia-inducible factor 1α (HIF-1α) and HIF-1α target genes. This study examines the addition of the hypoxia-activated chemotherapy TH-302 to VEGF-A inhibition and RT (a.k.a. trimodality therapy).

Methods:

Trimodality therapy was examined in two xenograft models and in vitro in tumour endothelial cells and sarcoma cell lines.

Results:

In both mouse models, VEGF-A inhibition and radiation showed greater efficacy than either therapy alone in slowing sarcoma growth. When TH-302 was added, this trimodality therapy completely blocked tumour growth with tumours remaining dormant for over 3 months after cessation of therapy. Trimodality therapy caused 2.6- to 6.2-fold more endothelial cell-specific apoptosis than bimodality therapies, and microvessel density and HIF-1α activity were reduced to 11–13% and 13–20% of control, respectively. When trimodality therapy was examined in vitro, increases in DNA damage and apoptosis were much more pronounced in tumour endothelial cells compared with that in sarcoma cells, especially under hypoxia.

Conclusions:

The combination of TH-302, VEGF-A inhibition, and RT is highly effective in preclinical models of sarcoma and is associated with increased DNA damage and apoptosis in endothelial cells and decreased HIF-1α activity.     

Define relative incomplete resection by highest mediastinal lymph node metastasis for non-small cell lung cancers: rationale based on prognosis analysis

Purpose

Present research aimed to explore the rationale of defining RIR operations by metastatic status of highest nodes.

Patients and methods

549 surgical patients, bearing pN2-NSCLCs, were enrolled in the current study. R1/R2 nodes on the right side and L4 nodes on the left were taken as the highest mediastinal lymph nodes. The operations were defined “Complete Resection (CR)” if the highest nodes were negative. Operations were otherwise “Relative Incomplete Resections (RIR)” if the nodes were positive. Exclusion criteria included: metastatic carcinomas or small cell lung cancer, prior history of induction therapy, exploratory thoracotomy, palliative resection, and massive pleural dissemination, as well as cases without “highest” mediastinal nodal pathology. The survival rate was calculated using the life-table and Kaplan-Meier method. Comparisons between groups were calculated using the Log-rank test.

Results

A total of 6865 lymph nodes (5705 mediastinal and 1160 regional, average 12.6 ± 6.4 nodes for each patient) were removed. Total cases included 246 RIR (100 left and 146 right side) and 303 CR (108 left and 195 right). The overall 5-year survival rate was 22% and the median survival time was 28.29 months. Five-year survival rates of the CR and RIR group were statistically significant (29% and 13%, respectively p < 0.0001). L4 and R1/R2 lymph nodes had similar position for defining RIR; no obvious survival difference was indicated between either side (p = 0.464 in CR groups, p = 0.647 in RIR groups). N2 subcategories and skip-metastasis were closely associated with highest nodal involvement (p < 0.0001). Multivariate analysis showed CR/RIR assignment, tumor size, N2 disease stratification, pathological T status, and number of positive mediastinal nodes were risk factors for 5-year survival in the present case series.

Conclusion

Involvement of the highest mediastinal lymph nodes is highly predictive of poor prognosis and indicates an advanced stage of the disease. Therefore, it may be appropriate to assign R1/R2 or L4 as criterion for defining RIR or CR cases in surgical NSCLC cases.     

A differential intra-operative molecular biological test for the detection of sentinel lymph node metastases in breast carcinoma. An extended experience from the first UK centre routinely offering the service in clinical practice

Introduction

One-Step Nucleic acid Amplification (OSNA) is a molecular biological assay of cytokeratin-19 (a breast epithelial marker) mRNA. It can be employed intra-operatively for detection of lymph node metastases in breast carcinoma. Patients with positive sentinel nodes may proceed to axillary lymph node dissection (ALND) level I or higher dependent upon the OSNA quantitative result, during the same surgical procedure, avoiding a second operation and eliminating the technical difficulties possibly associated with delayed ALND.

Aims

Our Breast Unit was the first in the UK to implement this novel technique in routine practice. This study reviews our first 44-month data following introduction of OSNA “live” on whole sentinel nodes following an extensive validation study (Snook et al.).⁹

Methods

Data was collected prospectively from the period of introduction 01/12/2008 to 30/08/2012. All patients eligible for sentinel node biopsy were offered OSNA and operations were performed by five consultant breast surgeons. On detection of macro-metastasis a level II/III and for a micro-metastasis a level I ALND was performed.

Results

A total of 859 patients (1709 sentinel lymph nodes) were analysed. All except one were females. The majority underwent wide local excision (73.4%, n = 631) or mastectomy 25% (n = 215) and 1.6% (13) underwent SLN biopsy alone. IDC was seen in 79% (n = 680) of the patients and 53.5% (n = 460) had grade II tumours. One-third (30.8%, n = 265) had positive sentinel nodes and had further axillary surgery at the time of SLN biopsy. Of these, 47% (n = 125/265) had macro-metastases, 38% (n = 101/265) had micro-metastases and 14.7% (n = 39/265) had “positive but inhibited” results. Positive non-sentinel lymph nodes (NSLN) were seen in 35% (44/125) of those with macro-metastases; 17.8% (18/101) of the patients with micro-metastases and 10.2% (4/39) of the “positive but inhibited” group.

Conclusion

In our series over a third of our patients had positive lymph nodes detected with OSNA allowing them to proceed directly to axillary surgery at the same operation. This technique eliminates the need for a second operation in sentinel lymph node positive patients and avoids the anxiety waiting for histological results.     

Everolimus in combination with letrozole inhibit human breast cancer MCF-7/Aro stem cells via PI3K/mTOR pathway: an experimental study

This study evaluated the effects of an mTOR inhibitor everolimus alone or in combination with letrozole on MCF-7/Aro (MCF-7 cells stably transfected with CYP19) in vitro and in vivo. In vitro studies, full-length CYP19 (aromatase) was cloned in a plasmid transfer vector pH ß-Aro and then transfected into MCF-7 stem cells which were ESA⁺CD44⁺CD24^?/low sorted by flow cytometry. MTT assays were used to quantify the inhibitory effect of the drugs on MCF-7/Aro stem cells (SCs) and non-stem cells (NSCs). Apoptosis and the cell cycle distributions of stem cells were examined by flow cytometry. The tumorigenicity of stem cells after treatment was investigated by soft agar colony formation assays. In vivo studies, the BALB/c mice were injected with MCF-7/Aro SCs, and the different treatments were administered. After necropsy, the expression of KI67, CD31, AKT1, phospho-AKT (Thr308), and mTOR was analyzed by immunohistochemistry. In vitro, compared with MCF-7/Aro NSCs, there were greater resistance to the standard treatment doses of letrozole and everolimus in MCF-7/Aro SCs (17- and 15-fold, respectively). Treatment with everolimus or letrozole resulted in growth inhibition of SCs in a dose-dependent manner. Compared with single-agent therapy, the combination of everolimus with letrozole was more effective in the inhibition of cell growth (P?<?0.001) and tumorigenicity (P?<?0.01). In addition, an increase in G1 cell cycle arrest and increases in early apoptosis were observed in the combination treatment group compared with either single-agent group. In vivo, the xenograft tumor sizes were significantly decreased in everolimus alone group compared to control group, and everolimus plus letrozole therapy was much more effective compared with either single agent alone (P?<?0.01). Compared with everolimus alone, the combination of everolimus and letrozole reduced the expression of KI67, mTOR, and phospho-AKT (Thr308; P?<?0.01). Everolimus has effective inhibition on aromatase-overexpressing stem cell in vitro and in vivo. The combination everolimus and letrozole could be more effective than either drug alone.     

Inhibition of the mitochondrial Hsp90 chaperone network: A novel,efficient treatment strategy for cancer?

Research has shown that cancer cells exhibit multiple deregulated pathways, involving proliferation, migration and cell death. Heat-shock-proteins have evolved as “central regulators” and are implicated in the modulation of these pathways and in organelle-specific signaling. In this instance, heat-shock-proteins (Hsps) assist cancer cells in the maturation of proteins. Hsp90 is of particular interest because its enzymatic ATPase activity is elevated in malignant cells as compared to non-neoplastic counterparts. Consistent with its high-activity in cancer cells, Hsp90 stabilizes a considerable number of proteins being instrumental in carcinogenesis and the maintenance and growth of highly malignant cancers. Among its distribution Hsp90 is also localized within mitochondria of neoplastic cells of various origin, interacting with another chaperone, TRAP1 (Tumor necrosis factor type 1 receptor-associated protein or Heat-shock-protein 75) to antagonize the cell death promoting properties of the matrix protein, Cyclophilin-D. Several preclinical studies, including in vivo studies in both orthotopic and genetic animal models, have confirmed that targeting mitochondrial Hsp90 may be a novel efficient treatment method for highly recalcitrant tumors. This review summarizes the most recent findings of mitochondrial Hsp90 signaling and its potential implications for cancer therapy.     

Ewing sarcoma dissemination and response to T-cell therapy in mice assessed by whole-body magnetic resonance imaging

Background:

Novel treatment strategies in Ewing sarcoma include targeted cellular therapies. Preclinical in vivo models are needed that reflect their activity against systemic (micro)metastatic disease.

Methods:

Whole-body magnetic resonance imaging (WB-MRI) was used to monitor the engraftment and dissemination of human Ewing sarcoma xenografts in mice. In this model, we evaluated the therapeutic efficacy of T cells redirected against the Ewing sarcoma-associated antigen G_D2 by chimeric receptor engineering.

Results:

Of 18 mice receiving intravenous injections of VH-64 Ewing sarcoma cells, all developed disseminated tumour growth detectable by WB-MRI. All mice had lung tumours, and the majority had additional manifestations in the bone, soft tissues, and/or kidney. Sequential scans revealed in vivo growth of tumours. Diffusion-weighted whole-body imaging with background signal suppression effectively visualised Ewing sarcoma growth in extrapulmonary sites. Animals receiving G_D2-targeted T-cell therapy had lower numbers of pulmonary tumours than controls, and the median volume of soft tissue tumours at first detection was lower, with a tumour growth delay over time.

Conclusion:

Magnetic resonance imaging reliably visualises disseminated Ewing sarcoma growth in mice. G_D2-retargeted T cells can noticeably delay tumour growth and reduce pulmonary Ewing sarcoma manifestations in this aggressive disease model.