Unlocking new contrast in a scanning helium microscope

Delicate structures (such as biological samples, organic films for polymer electronics and adsorbate layers) suffer degradation under the energetic probes of traditional microscopies. Furthermore, the charged nature of these probes presents difficulties when imaging with electric or magnetic fields, or for insulating materials where the addition of a conductive coating is not desirable. Scanning helium microscopy is able to image such structures completely non-destructively by taking advantage of a neutral helium beam as a chemically, electrically and magnetically inert probe of the sample surface. Here we present scanning helium micrographs demonstrating image contrast arising from a range of mechanisms including, for the first time, chemical contrast observed from a series of metal–semiconductor interfaces. The ability of scanning helium microscopy to distinguish between materials without the risk of damage makes it ideal for investigating a wide range of systems.

Scanning helium microscopy uses neutral atoms to image traditionally challenging materials (e.g. delicate, insulating and magnetic samples) non-destructively with absolute surface sensitivity. This work reports the first observation of chemical contrast in helium microscopy via inelastic scattering.

A highly contrasting scanning helium microscope

We present a scanning helium microscope equipped to make use of the unique contrast mechanisms, surface sensitivity, and zero damage imaging the technique affords. The new design delivers an order of magnitude increase in the available helium signal, yielding a higher contrast and signal-to-noise ratio. These improvements allow the microscope to produce high quality, intuitive images of samples using topological contrast, while setting the stage for investigations into further contrast mechanisms.

High protein expression of EZH2 is related to unfavorable outcome to tamoxifen in metastatic breast cancer

BACKGROUND

Metastatic breast cancer (MBC) is a highly heterogeneous disease with great differences in outcome to both chemo- and endocrine therapy. Better insight into the mechanisms underlying resistance is essential to better predict outcome to therapy and to obtain a more tailored treatment approach. We have previously described that increased mRNA expression levels of Enhancer of Zeste homolog (EZH2) are associated with worse outcome to tamoxifen therapy in MBC. Here, we explored whether this is also the case for EZH2 protein expression.

PATIENTS AND METHODS

A tissue microarray (TMA) was created using formalin-fixed, paraffin-embedded estrogen receptor (ER)-positive primary breast tumor tissues of 250 MBC patients treated with first-line tamoxifen. Quantity and intensity of EZH2 expression were determined by immunohistochemistry (IHC) and both were used to generate and group scores according to a previously described method for scoring EZH2.

RESULTS

In total, 116 tumors (46%) were considered to be EZH2 positive. The presence of EZH2 protein expression was significantly associated with progression-free survival (PFS) in both univariate [hazard ratio (HR) 1.51, 95% confidence interval (CI) 1.17-1.97, P = 0.002] and multivariate analysis including traditional factors associated with tamoxifen outcome (HR 1.41, 95% CI 1.06-1.88, P = 0.017). Considering quantity irrespective of intensity, tumors with >50% EZH2-positive cells had the worst PFS (HR 2.15, 95% CI 1.42-3.27, P < 0.001), whereas intensity alone did not show a significant association with PFS. Application of other methods of scoring EZH2 positivity resulted in a similar significant association between the amount of EZH2 positive cells and PFS.

CONCLUSION

In addition to EZH2 mRNA levels, these results suggest that protein expression of EZH2 can be used as a marker to predict outcome to tamoxifen therapy. This provides new rationale to explore EZH2 inhibition in the clinical setting and increases the possibilities for a more personalized treatment approach in MBC patients.

Imiquimod 5% cream as pretreatment of Mohs micrographic surgery for nodular basal cell carcinoma in the face: a prospective randomized controlled study

BACKGROUND

Imiquimod 5% cream can reduce or clear superficial and small nodular basal cell carcinoma (BCC). It could be used as a pretreatment of Mohs micrographic surgery (MMS) to decrease defect size.

OBJECTIVES

To study if a pretreatment with imiquimod 5% cream decreases defect size after MMS. In addition, to study the effect on the number of Mohs stages and reconstruction time.

METHODS

Seventy patients aged >18 years with a primary nodular BCC in the face were included. The imiquimod group used imiquimod 5% cream for 4 weeks, before MMS. The control group was treated with MMS only. Tumour and defect sizes were measured. We noted the number of Mohs stages, reconstruction time and side-effects.

RESULTS

The median percentage increase in area from tumour size at baseline to the post-MMS defect for the imiquimod group was significantly less compared with the control group, 50% vs. 147% (P < 0·001). A tendency towards fewer Mohs stages in the imiquimod group was observed and the reconstruction time was significantly shorter in this group (P = 0·01).

CONCLUSIONS

Imiquimod 5% cream as pretreatment of MMS significantly reduced the tumour size in primary nodular BCC and reduced the surgical defect size. Further research is necessary to investigate cost-effectiveness.

Relocatable fixation systems in intracranial stereotactic radiotherapy. Accuracy of serial CT scans and patient acceptance in a randomized design

PURPOSE

The goal was to provide a quantitative evaluation of the accuracy of three different fixation systems for stereotactic radiotherapy and to evaluate patients' acceptance for all fixations.

METHODS

A total of 16 consecutive patients with brain tumours undergoing fractionated stereotactic radiotherapy (SCRT) were enrolled after informed consent (Clinical trials.gov: NCT00181350). Fixation systems evaluated were the BrainLAB® mask, with and without custom made bite-block (fixations S and A) and a homemade neck support with bite-block (fixation B) based on the BrainLAB® frame. The sequence of measurements was evaluated in a randomized manner with a cross-over design and patients' acceptance by a questionnaire.

RESULTS

The mean three-dimensional (3D) displacement and standard deviations were 1.16 ± 0.68 mm for fixation S, 1.92 ± 1.28 and 1.70 ± 0.83 mm for fixations A and B, respectively. There was a significant improvement of the overall alignment (3D vector) when using the standard fixation instead of fixation A or B in the craniocaudal direction (p = 0.037). Rotational deviations were significantly less for the standard fixation S in relation to fixations A (p = 0.005) and B (p = 0.03). EPI imaging with off-line correction further improved reproducibility. Five out of 8 patients preferred the neck support with the bite-block.

CONCLUSION

The mask fixation system in conjunction with a bite-block is the most accurate fixation for SCRT reducing craniocaudal and rotational movements. Patients favoured the more comfortable but less accurate neck support. To optimize the accuracy of SCRT, additional regular portal imaging is warranted.

P5-06-08: Mesenchymal Stem Cells and Carcinoma-Associated Fibroblasts Sensitize Breast Cancer Cells in 3D Cultures to Kinase Inhibitors

Background: Bone-derived mesenchymal stem cells (MSCs) are attracted to cancer lesions and may differentiate to CAFs. By interacting with cancer cells, MSCs and CAFs may promote cancer progression and modulate drug sensitivity.

Material and Methods: To analyze ability of MSCs and CAFs to modulate drug response, we generated spheroids of MCF-7 or MDA-MB-231 breast cancer cells in the absence or presence of human (h) MSCs or hCAFs and tested the susceptibility of the breast cancer cells to three different kinase inhibitors (TKI258, RAD001 and RAF265) as used in cancer therapy.

Results: While MSCs and CAFs did not affect the response of either breast cancer cell line to PDGFR/FGFR/VEGFR inhibitor TKI258, they sensitized breast cancer cells to the mTOR inhibitor RAD001. In MCF-7 cells, this was accompanied by increased apoptosis. hMSCs and to a lesser extent hCAFs also enhanced the cytotoxic effect of RAF inhibitor RAF265 on MDA-MB-231 cells. Searching for the mechanism that underlies the effect of stromal cells on RAF265 response we found that stromal cells inhibited RAF265-induced increase in ERK1/2 phosphorylation, supported RAF265-dependent downregulation of PKCalpha (protein kinase Calpha) and prevented RAF265-induced conversion of LC3B, a marker of autophagy. To mimic the changes in ERK1/2 phosphorylation and PKCalpha expression in response to the stromal cells, we treated cells with MEK1 inhibitor U0126 or PKCalpha inhibitor Gö6976, respectively. U0126, but not Gö6976, was as effective as hMSCs in sensitizing MDA-MB-231 cells to RAF265.

Discussion: Our data suggest that hMSCs and hCAFs increased the cytotoxic effect of RAF265 on MDA-MB-231 cells by downregulating ERK1/2 phosphorylation. In summary, this study shows that hMSCs are able to render breast cancer cells more susceptible to kinase inhibitors and that, to the most part, hCAFs to which hMSCs can differentiate are able to mimic the drug-sensitizing effects of hMSCs.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-06-08.

Abstract P4-02-16: High miRNA26A1 and Low EZH2 Expression Levels Are Associated with Favorable Outcome to Tamoxifen in Advanced Breast Cancer through Similar Molecular Pathways

Background: We showed that decreased expression levels of EZH2 are associated with a favorable outcome to tamoxifen in advanced breast cancer. Furthermore, EZH2 knockdown in MCF7 cells resulted in estrogen receptor (ER) upregulation and increased sensitivity to anti-estrogens. Recently, EZH2 has been identified as a target of miRNA26A1 and miRNA101.

Objective: To associate miRNA26A1 and miRNA101 expression levels with: A) EZH2 and B) molecular pathways and C) outcome to first-line tamoxifen monotherapy for advanced disease.

Materials & Methods: Expression levels of miRNA26A1, miRNA101, EZH2 and references (miRNA-132 and miRNA-374) were measured using quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) in 235 ER-positive primary breast cancer specimens from patients with advanced disease. The levels of expression were related to clinicopathologic factors and disease outcome. Pathway analysis was performed in a subset of 65 ER-positive tumors with available gene expression microarray data available. Computations were performed with STATA and P-values &lt;0.05 were considered statistically significant.

Results: The miRNA26A1 levels were significantly associated with levels of ER, progesterone (PgR), HER2 and EGFR, whereas miRNA101 levels showed significant relations with PgR expression and menopausal status. The miRNA26A1 and miRNA101 levels showed an inverse relation with EZH2 mRNA levels (Spearman Rank Correlation of -0.21 and -0.15, respectively, P&lt;0.05). As continuous variable in univariate analysis, miRNA26A1 (Hazard Ratio (HR) =0.13, 95 % CI: 0.06-0.28) correlated with Time to Progression (TTP), while miRNA101 did not (HR=0.87, 95% CI: 0.70-1.07). In multivariate analysis including traditional predictive factors, the third with highest miRNA26A1 levels (HR=0.49, 95% CI: 0.34-0.72) alone, or combined with the third with lowest EZH2 levels (HR=0.56, 95% CI: 0.35-0.88) were associated with a favorable TTP independently of traditional factors. Pathway analyses identified 2 overlapping, cell cycle, related pathways with two genes (CCNE1and CDC2) differentially expressed (P&lt;0.05) between tumors with high and low levels of miRNA26A1 and EZH2, respectively. Levels of CCNE1 and CDC2 were tested in the 235 tumors and showed as continuous variables also a significant association with TTP (HR=1.27, 95% CI: 1.12-1.45 and HR=1.53, 95% CI: 0.129-1.81).

Conclusions: The miRNA26A1 and miRNA101 levels have an inverse relation with levels of EZH2, however, only miRNA26A1 has predictive value in advanced breast cancer. Pathways comparison between miRNA26A1 and EZH2 identified 2 overlapping cell cycle related pathways and the genes CCNE1 and CDC2. Low levels of EZH2, CCNE1 and CDC2 and high levels of miRNA26A1 are associated with a favorable outcome to tamoxifen therapy.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-02-16.

Complete response of a metastatic gastroesophageal adenocarcinoma on irinotecan-based chemotherapy in a dialysis patient

We present the first case report of a complete response of metastatic gastroesophageal cancer in a chronic hemodialysis patient with irinotecan-based chemotherapy. An elderly dialysis patient presented with diffuse liver metastases by a gastroesophageal adenocarcinoma. He received combination chemotherapy with 5 fluorouracil and irinotecan. After six months of chemotherapy, liver scans show complete remission. The principles, practice, and experience of chemotherapy with irinotecan during dialysis are discussed.

Integrated Genomic Profiling of Endocrine Therapy Response in Advanced Breast Cancer

PurposeIn hormone receptor positive breast cancer the response rates for endocrine treatment, i.e. tamoxifen (TAM) or aromatase inhibitors (AIs), are only 50 to 70% in the advanced disease setting. The overall aim of this retrospective study is to identify a molecular signature using integrated genomic profiling to improve prediction of endocrine treatment outcome in the advanced disease setting.ObjectivesA) To compare mRNA expression profiles of TAM- and AI-treated patients and to identify genes and pathways associated with treatment outcome.B) To discover miRNA and mRNA signatures predictive for AI response.Patients and MethodsFresh frozen Estrogen Receptor (ER)-positive primary breast cancer specimens from patients with advanced disease treated with first-line AIs (N=55) or TAM (N=109) were analyzed. Expression profiles of 670 miRNAs and 44K mRNAs were generated using multiplex qRT-PCR and microarrays. Profiles were related to clinical response and time to progression (TTP). Statistical and bio-informatic tools were applied to discover and combine markers into an integrated genomic predictive signature. The nearest centroid prediction method of BRB-ArrayTools (Version3.7.0) was used to assess the predictive value.ResultsThe quality controlled and informative expression profiles of 277 miRNAs and 14112 mRNAs in 50 AI-treated tumors and 10433 mRNAs in 101 TAM-treated tumors were included for further analysis in the discovery phase.Global testing of mRNAs linked to Biocarta pathways demonstrated the involvement of the interferon pathway in endocrine therapy response in both AI- and TAM-treated patients. Using BRB-ArrayTools survival analysis to find genes associated with TTP (P&lt;0.05), we identified 1002 mRNAs in AI-treated and 662 mRNAs in TAM-treated tumors to be significantly related with TTP.The overlap of 40 mRNAs between AI- and TAM-treatment was defined as a mRNA signature for endocrine treatment outcome. In TAM-treated patients this classifier has a 69% accuracy (63% sensitivity, 74% specificity), an odds ratio for clinical benefit of 4.69 (95% CI 1.99-11.05, P&lt;0.001) and a hazard ratio for TTP of 0.17 (95% CI 0.10-0.29, P&lt;0.001). In AI-treated patients, this 40mRNA signature has a performance of 78% accuracy (84% sensitivity, 62% specificity) and significantly predicts clinical benefit (odds ratio = 8.27, 95% CI 2.00-34.3, P=0.004) and TTP (hazard ratio = 0.07, 95% CI 0.02-0.22, P&lt;0.001).After statistical analysis a 16 miRNAs classifier for AI-treatment outcome was identified with a performance of 78% accuracy (89% sensitivity, 46% specificity). This classifier significantly predicts clinical benefit (Odds ratio = 7.07, 95% CI 1.57-31.9, P=0.011) and TTP (hazard ratio = 0.24, 95% CI 0.09-0.61, P=0.003).The genomic mRNA and miRNA signatures are currently integrated and validated in additional samples as well as “in silico” on tumors treated with neo-adjuvant AI (Miller et al, JCO 2009).ConclusionThis is the first study that combines miRNA and mRNA profiling in an attempt to define an integrated genomic signature for endocrine treatment outcome. Additional prospective multicenter studies are needed to confirm the predictive value of this signature.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3029.

Methylated genes as new cancer biomarkers

Aberrant hypermethylation of promoter regions in specific genes is a key event in the formation and progression of cancer. In at least some situations, these aberrant alterations occur early in the formation of malignancy and appear to be tumour specific. Multiple reports have suggested that measurement of the methylation status of the promoter regions of specific genes can aid early detection of cancer, determine prognosis and predict therapy responses. Promising DNA methylation biomarkers include the use of methylated GSTP1 for aiding the early diagnosis of prostate cancer, methylated PITX2 for predicting outcome in lymph node-negative breast cancer patients and methylated MGMT in predicting benefit from alkylating agents in patients with glioblastomas. However, prior to clinical utilisation, these findings require validation in prospective clinical studies. Furthermore, assays for measuring gene methylation need to be standardised, simplified and evaluated in external quality assurance programmes. It is concluded that methylated genes have the potential to provide a new generation of cancer biomarkers.

Harmonisation of multi-centre real-time reverse-transcribed PCR results of a candidate prognostic marker in breast cancer: an EU-FP6 supported study of members of the EORTC - PathoBiology Group

AIM

Assessment of intra- and inter-laboratory variation in multi-centre real-time reverse-transcribed PCR (qRT-PCR)-based mRNA quantification of a prognostic marker in breast cancer using external quality assurance (EQA).

METHODS

A questionnaire on the methodologies used and EQA calibrators were sent to 5 participating laboratories from 4 European countries, which measured mRNA levels of PITX2 splice variants and reference genes by qRT-PCR.

RESULTS

Differences in the methodology included PCR quantification methodology and equipment, RNA extraction and cDNA synthesis procedures. The intra-laboratory coefficient of variation (CV) ranged from 5 to 23%, and the inter-laboratory CV ranged from 17 to 30%. The inter-laboratory CV was reduced to 13% by using prediluted calibrators and by harmonising the data in the central QA laboratory. Additional normalisation using reference genes did not decrease the variation further.

CONCLUSIONS

Both externally provided calibrators and centralised harmonisation are required to reduce the intra-laboratory variation in multi-centre qRT-PCR results to an acceptable level.