Effects of grafting on key photosynthetic enzymes and gene expression in the citrus cultivar Huangguogan

Grafting influences scion photosynthetic capacity and fruit quality. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), which strongly affects photosynthetic rate, and Rubisco activase (RCA), which regulates Rubisco activity, are two key photosynthetic enzymes. However, little information is available regarding the effect of grafting on the concentration and expression of Rubisco and RCA in the citrus cultivar Huangguogan. The objective of this study was to investigate the effect of grafting Huangguogan plants onto trifoliate orange, tangerine, and orange on: 1) the concentration of Rubisco and RCA; 2) the mRNA levels of rbcL, rbcS, and rca; and 3) fruit quality. Overall, the results showed that when Huangguogan plants budded on tangerine and orange, they had better fruit quality, while on trifoliate orange they had higher Rubisco concentration. Tangerine and orange are probably the most suitable rootstocks for Huangguogan plants given the environmental conditions of Sichuan Province, China.

Abstract P2-05-23: TWIST1 silences FOXA1 transcription to promote breast cancer progression

TWIST1 promotes epithelial-mesenchymal transition (EMT), invasion and metastasis of breast cancer cells, but the underlying mechanism is still not well understood. We generated mammary gland tumor specific Twist1 knock out mouse model and found that TWIST1 does not affect PyMT-induced mammary tumor initiation and growth but promotes tumor lung metastasis. We identified FOXA1 as a novel direct target of TWIST1 in both mouse and human breast cancer. We further found that TWIST1 inhibits FOXA1 expression through direct binding to its proximal promoter region and recruiting Mi2/nucleosome remodeling and deacetylase (Mi2/NuRD) transcriptional repressor complex. Moreover, TWIST1 also diminished transcriptional activator AP1 binding to FOXA1 promoter. TWIST1 mediated FOXA1 down-regulation is essential for promoting breast cancer migration, invasion and metastasis. FOXA1 significantly inhibits TWIST1 dependent cell migration and invasion capability of MCF7 cells through inhibiting integrin α5, β1 and MMP9 expression. Importantly, TWIST1high FOXA1low correlates with the poorest prognosis in breast cancer patients.

Citation Format: Xu Y, Feng Z, Xu Y, Mo Q, Qin L, Sun T, Wu H, Li Y, Liao L, Xu J. TWIST1 silences FOXA1 transcription to promote breast cancer progression. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-05-23.

Abstract P3-07-32: Tumour infiltrating lymphocyte (TIL) and chemokine gene signature predicts for benefit of anthracycline-containing chemotherapy in breast cancer patients

Background: The contribution of immune cells has long been appreciated in tumour development and disease progression; however, their translational potential as cancer-associated prognostic and predictive markers was only recently recognized. High densities of tumour-infiltrating lymphocytes (TILs) correlate with improved clinical outcome in breast cancer; whether TILs also predict anthracycline benefit in all, or only a particular subgroup, of breast cancer patients remains largely unknown. Furthermore, since identification of TILs is generally based on H&E staining, it has not previously been possible to evaluate relative contribution of distinct T-cell types, and B cells, to patient outcome.

Methods: We assessed 290 patient samples from the BR9601 adjuvant breast cancer trial for the capacity of TIL contexture to predict for anthracycline (E-CMF) benefit over CMF. We immunoprofiled patient samples on the Nanostring platform to gain insight into the impact of lymphocyte populations predicting for anthracycline benefit. Our immunoprofiling panel included 38 genes representing TIL-gene signatures and chemokines that may be responsible for recruiting TILs to the tumour site.

Results: The analyses revealed two important findings. First, refinement of the 38-gene panel resulted in the generation of a novel 9-gene signature that includes cytotoxic T lymphocytes (CTL) and chemokine genes. Low CTL gene expression correlated with ER+ expression while high expression correlated with ER- expression (p<0.0001), consistent with the notion that high TIL densities are predominantly observed in non-luminal breast cancers. Second, in an univariate Cox regression analysis, this 9-gene signature was a predictive biomarker of anthracycline benefit with respect to breast-cancer specific OS (HR: 0.371, 95%CI 0.158-0.868, p=0.022) and DRFS (HR: 0.395, 95%CI 0.172-0.907, p=0.028); this effect was no longer significant after adjustment for other prognostic factors (OS HR: 0.437, 95%CI 0.166-1.150, p=0.094; DRFS HR: 0.488, 95%CI 0.185-1.287, p=0.147).

Conclusion: This study highlights the significance of assessing the entire tumour since TILs, tumour and stromal cells collectively engage in a complex interplay that contributes to disease development and progression. Importantly, it reveals that not only CTLs but also chemokines may be clinically relevant and should be validated as potential biomarkers of anthracycline benefit and as therapeutic targets.

Citation Format: Braunstein M, Yao C, Lyttle N, Liao L, Boutros PC, Twelves CJ, Bartlett JMS, Spears M. Tumour infiltrating lymphocyte (TIL) and chemokine gene signature predicts for benefit of anthracycline-containing chemotherapy in breast cancer patients. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-32.

Abstract P2-04-01: The role of Jmjd1a in mammary gland development and breast tumor growth

Histone modification alters chromatin architecture and thereby influences gene transcription. Histone methylation status is reversible and counter-regulated by methyltransferases and demethylases. Jmjd1a (also known as KDM3A, TSGA, JMJD1, JHDM2A and JHMD2A) is a histone demethylase. It belongs to JmjC domain-containing protein family and could specifically remove di- and mono- methyl residues from di or mono-methylated histone H3K9 (H3K9me2/me1). Recent studies showed that Jmjd1a plays an important role in embryonic stem cell self-renewal, spermatogenesis, regulation of metabolic gene expression and body weight, sex determination, tumor angiogenesis, and macrophage infiltration. However, its role in mammary gland (MG) development, breast carcinogenesis and breast cancer progression hasn't been systemically investigated. In this study, we found that Jmjd1a is expressed in mouse luminal epithelial cells. Genetic disruption of the Jmjd1a gene significantly slowed down MG development as indicated by retarded MG elongation and decreased ductal density in virgin mice observed at the ages of 4, 6 and 8 weeks. In agreement with the retarded MG development, the expression of Ki67 and cyclinD1 in epithelial cells of MGs from Jmjd1a knockout (KO) mice dramatically reduced compared with that from wild type (WT) mice. H3K9me1 and H3K9me2 levels in the epithelial cells of KO MGs are much higher than that in WT MGs. To assess the role of Jmjd1a in breast cancer progression, we crossbred Tg(Jmjd1a-/-) mice with MMTV-TVA(RCAS-PyMT) mice and obtained Tg(Jmjd1a-/-)×MMTV-TVA(RCAS-PyMT) mice. Infection of the TVA-expressing MG epithelial cells with the RCAS-PyMT virus induced mammary tumors in these mice and MMTV-TVA(RCAS-PyMT) control mice. We found that KO of Jmjd1a slightly accelerated mammary tumor initiation but significantly decreased tumor growth. Ki67 and cyclinD1 expression statistically reduced in KO tumors versus WT tumors. At the molecular level, Jmjd1a expression positively correlated with cyclin D1 expression in mammary epithelial cells and mammary tumors. Knockdown of Jmjd1a in MCF-7 cells significantly reduced cyclin D1 expression, while ectopic expression of Jmjd1a in MCF-7 cells increased cyclin D1 expression. ChIP assay revealed that Jmjd1a is associated with a promoter region of cyclin D1. Co-expression of c-Myc and Jmjd1a boosted the activity of the cyclin D1 reporter. In conclusion, our study indicated that Jmjd1a plays an important role in promoting mammary gland development and breast tumor growth by up-regulating cyclin D1 expression. Targeting Jmjd1a may inhibit breast cancer progression.

Citation Format: Qin L, Xu Y, Wu Y, Yu X, Toneff MJ, Liao L, Li Y, Xu J. The role of Jmjd1a in mammary gland development and breast tumor growth. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-04-01.

Abstract P3-06-03: Downregulation of histone H2A and H2B pathways is associated with anthracycline sensitivity in breast cancer

Background: Meta-analyses performed by the Early Breast Cancer Trialists Collaborative Group demonstrated a significant increase in disease free and overall survival through the addition of anthracyclines to polychemotherapy. Anthracyclines have, however, significant toxicities including cardiotoxicity and leukaemia. It is, therefore, imperative to identify those patients who will benefit from adjuvant anthracycline treatment; other patients could then be spared unnecessary toxicities and be considered for alternative adjuvant therapy. Several markers that may predict anthracycline benefit have been explored in patient cohorts (HER2, TOP2A, Ch17CEP and TIMP1) with limited success.

Methods: To identify markers that are clinically-relevant, we generated MDA-MB-231, MCF7, SKBR3 and ZR-75-1 breast cancer cell lines sensitive and resistant to epirubicin to identify pathways contributing to anthracycline resistance. A complementary approach including gene expression analyses to identify molecular pathways involved in resistance, and small-molecule inhibitors to reverse resistance were performed. RNA was extracted from patients in the BR9601 adjuvant trial evaluating the addition of epirubicin (E) to CMF and analysed through Nanostring technology. Log-rank analyses explored the predictive values of the signatures on distant relapse-free survival (DRFS). Cox-regression models tested independent predictive value on DRFS in the presence of treatment, age, tumour size, nodal status, ER status and grade, and treatment by marker interactions.

Results: Gene expression analysis identified upregulaton of a histone gene module in all four cell lines which was validated by qRT-PCR. Histone deacetylase small-molecule inhibitors reversed resistance and were cytotoxic for epirubicin-resistant cell lines, with IC50's ranging from 0.1-3.69µM, confirming that histone pathways are associated with epirubicin resistance. Gene expression analysis of the 18-gene histone module in the BR9601 clinical cohort revealed that patients whose tumour had low expression had an increased DRFS (HR: 0.35, 95%CI 0.17-0.73, p=0.005) when treated with E-CMF compared with patients treated with CMF alone. Conversely, there was no apparent benefit of E-CMF vs CMF in patients with high histone module expression (HR: 0.96, 95%CI 0.58-1.59, p=0.87). After multivariate analysis and adjustment for HER2 status, nodal status, age, grade and ER status, the treatment by marker interaction was 0.35 (95%CI 0.13-0.96, p=0.042) for DRFS.

Conclusion: Histone gene expression was an independent predictor of anthracycline benefit in terms of DRFS. In vitro data demonstrated that resistance could be reversed with histone deacetylase small-molecule inhibitors. The histone signature identified could be a potential theranostic candidate for patients with early breast cancer.

Citation Format: Spears M, Braunstein M, Liao L, Yao C, Lyttle N, Lobo N, Taylor KJ, Krzyzanowski PM, Kalatskaya I, Marcellus R, Stein L, Boutros P, Twelves CJ, Bartlett JMS. Downregulation of histone H2A and H2B pathways is associated with anthracycline sensitivity in breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-06-03.

793 nm pump induced photo-bleaching of photo-darkened Yb(3+)-doped fibers

We report on the strong photo-bleaching of the photo-darkening (PD) induced loss under the cladding pump of a 793 nm laser diode (LD) in double clad Yb-doped fibers. Up to 68% PD loss at 810 nm was bleached. The bleaching rates under different powers show that the higher pump power corresponds to the more bleached loss within the same time. Moreover, repeatable processes of PD and photo-bleaching were observed when alternately pumped with 915 and 793 nm LDs. Furthermore, it was found that simultaneously pumping the fiber with 915 and 793 nm LDs can suppress about 80% PD loss, compared with pumping the fiber only with 915 nm LD. The mechanism of photo-bleaching under 793 nm pump was also discussed.

RANTES and SDF-1 Are Keys in Cell-based Therapy of TMJ Osteoarthritis

The present study aimed to investigate the therapeutic effect of injections of local bone marrow mesenchymal stem cells (BMSCs) on osteoarthritis (OA) of the temporomandibular joint (TMJ) and to explore the role of stromal cell-derived factor 1 (SDF-1) and regulated on activation, normal T-cell expressed and secreted (RANTES) in this effect. Fundamentally, OA of the TMJ was induced by unilateral anterior crossbite in mice. Exogenous green fluorescent protein-labeled BMSCs (GFP-BMSCs) were weekly injected into the TMJ region for 4, 8, and 12 wk. The reparative effects of exogenous GFP-BMSCs were investigated by morphological observation and micro-computed tomography. The differentiation of GFP-BMSCs in the cartilage was examined by double immunofluorescence of GFPs with type II collagen, and the expression of related factors in the condylar cartilage was quantified by real-time polymerase chain reaction. The role of RANTES and SDF-1 in the therapeutic effect of exogenous BMSCs was examined by both in vitro and in vivo studies. The OA cartilage of the TMJ displays a synchronous increase in SDF-1 and RANTES expression and a higher capability of attracting the migration of GFP-BMSCs. The implanted GFP-BMSCs differentiated into type II collagen-positive cells and reversed cartilage degradation and subchondral bone loss in mice with OA of the TMJ. The migration of GFP-BMSCs towards OA cartilage and the rescuing effect of GFP-BMSC injections were impaired by the inhibitors of C-X-C chemokine receptor type 4 (CXCR4) and C-C chemokine receptor type 1 (CCR1), which are the receptors of SDF-1 and RANTES, respectively. Our data indicated that SDF-1/CXCR4 and RANTES/CCR1 signals are pivotal and function synergistically in the recruitment of GFP-BMSCs towards degraded cartilage in mice OA of the TMJ.

MiR-26a functions oppositely in osteogenic differentiation of BMSCs and ADSCs depending on distinct activation and roles of Wnt and BMP signaling pathway

MicroRNAs (miRNAs) emerge as important regulators of stem cell lineage commitment and bone development. MiRNA-26a (miR-26a) is one of the important miRNAs regulating osteogenic differentiation of both bone marrow-derived mesenchymal stem cells (BMSCs) and adipose tissue-derived mesenchymal stem cells (ADSCs). However, miR-26a functions oppositely in osteogenic differentiation of BMSCs and ADSCs, suggesting distinct post-transcriptional regulation of tissue-specific MSC differentiation. However, the molecular basis is largely unknown. Here, we report that the function of miR-26a is largely depended on the intrinsic signaling regulation network of MSCs. Using bioinformatics and functional assay, we confirmed that miR-26a potentially targeted on GSK3β and Smad1 to regulate Wnt and BMP signaling pathway. Overall comparative analysis revealed that Wnt signaling was enhanced more potently and played a more important role than BMP signaling in osteogenic differentiation of BMSCs, whereas BMP pathway was more essential for promoting osteogenic differentiation of ADSCs. The distinct activation pattern and role of signaling pathways determined that miR-26a majorly targeted on GSK3β to activate Wnt signaling for promoting osteogenic differentiation of BMSCs, whereas it inhibited Smad1 to suppress BMP signaling for interfering with the osteogenic differentiation of ADSCs. Taken together, our study demonstrated that BMSCs and ADSCs applied different signaling pathway to facilitate their osteogenic differentiation, which determined the inverse function of miR-26a. The distinct transcriptional regulation and post-transcriptional regulation network suggested the intrinsic molecular differences between tissue-specific MSCs and the complexity in MSC research and MSC-based cell therapy.

ProLuCID: An improved SEQUEST-like algorithm with enhanced sensitivity and specificity

ProLuCID, a new algorithm for peptide identification using tandem mass spectrometry and protein sequence databases has been developed. This algorithm uses a three tier scoring scheme. First, a binomial probability is used as a preliminary scoring scheme to select candidate peptides. The binomial probability scores generated by ProLuCID minimize molecular weight bias and are independent of database size. A modified cross-correlation score is calculated for each candidate peptide identified by the binomial probability. This cross-correlation scoring function models the isotopic distributions of fragment ions of candidate peptides which ultimately results in higher sensitivity and specificity than that obtained with the SEQUEST XCorr. Finally, ProLuCID uses the distribution of XCorr values for all of the selected candidate peptides to compute a Z score for the peptide hit with the highest XCorr. The ProLuCID Z score combines the discriminative power of XCorr and DeltaCN, the standard parameters for assessing the quality of the peptide identification using SEQUEST, and displays significant improvement in specificity over ProLuCID XCorr alone. ProLuCID is also able to take advantage of high resolution MS/MS spectra leading to further improvements in specificity when compared to low resolution tandem MS data. A comparison of filtered data searched with SEQUEST and ProLuCID using the same false discovery rate as estimated by a target-decoy database strategy, shows that ProLuCID was able to identify as many as 25% more proteins than SEQUEST. ProLuCID is implemented in Java and can be easily installed on a single computer or a computer cluster. This article is part of a Special Issue entitled: Computational Proteomics.

Isolation and characterization of microsatellite markers for Axonopus compressus (Sw.) Beauv. (Poaceae) using 454 sequencing technology

Axonopus compressus (Sw.) Beauv. is a perennial herb widely used as a garden lawn grass. In this study, we used Roche 454 pyrosequencing, combined with the magnetic bead enrichment method FIASCO, to isolate simple sequence repeat markers from the A. compressus genome. A total of 1942 microsatellite loci were identified, with 53,193 raw sequencing reads. One hundred micro-satellite loci were selected to test the primer amplification efficiency in 24 individuals; 14 primer pairs yielded polymorphic amplification products. The number of observed alleles ranged from two to six, with an average of 3.5. Shannon's Information index values ranged from 0.169 to 0.650, with an average of 0.393. Nei's genetic diversity values ranged from 0.108 to 0.457, with an average of 0.271. This first set of microsatellite markers developed for Axonopus will assist in the development of molecular marker-assisted breeding and the assessment of genetic diversity in A. compressus.

A polymorphism in the DNA repair domain of APEX1 is associated with the radiation-induced pneumonitis risk among lung cancer patients after radiotherapy

OBJECTIVE

To examine the association of tag single nucleotide polymorphisms (tagSNPs) (rs1130409, rs1760944, rs2307486 and rs3136817) in APEX1 with the risk of severe radiation-induced pneumonitis (RP) after radiotherapy among Han Chinese patients with lung cancer.

METHODS

A total of 168 patients with lung cancer who were receiving radiotherapy were prospectively recruited. RP was evaluated according to the Radiation Therapy Oncology Group. A case-control study was performed. The case group included patients with RP grade of ≥3, while the control group comprised patients with RP grades <3. Four tagSNPs of APEX1 were genotyped in 126 patients with complete follow-up by multi-SNaPshot® (Genesky Biotechnologies Inc., Shanghai, China) genotyping assays. RESULTS were assessed by a logistic regression model for RP risk and Mantal-Cox log-rank test for the cumulative RP probability by the genotypes.

RESULTS

rs1130409 was associated with severe RP. GT genotype of rs1130409 was significantly higher in patients with RP than in those of the control group [68.8% vs 41.8%; p = 0.025; resulting odds ratio (OR), 5.98]. Patients with lung cancer bearing the G allele had a 5.83-fold higher risk of RP than those with the wild TT genotype [OR = 5.83; 95% confidence interval (CI), 1.27-26.90; p = 0.024], and this was further confirmed by the binary regression adjusted by some confounding factors, including Karnofsky performance scale, concurrent chemotherapy-radiotherapy and lung volume receiving >30 Gy (OR = 6.96; 95% CI, 1.36-35.77; p = 0.02). rs1130409 was also associated with the time to occurrence of severe RP (p = 0.04). Three-dimensional model APEX1 protein showed that rs1130409 is located in the random coil structure corresponding to the DNA repair function region.

ADVANCES IN KNOWLEDGE

rs1130409 of APEX1 can be a predictor of RP grades ≥3 among patients with lung cancer.

Identification of candidate serum biomarkers for small cell lung cancer by proteomics analysis

AIM

Detection of novel tumor biomarker will aid in diagnosis of early-stage small cell lung cancer (SCLC). The purpose of this study was to identify novel tumor biomarker in serum from patients with SCLC using a proteomics-based approach.

METHODS

Sera were analyzed before the initiation of chemotherapy. Serum proteins of SCLC patients and healthy controls were collected and separated by 2-D fluorescence differential gel electrophoresis (2-D DIGE). Positive spots were analyzed by LC-MS/MS. Different expression of identified biomarker was verified by immunohistochemical method in wax specimen from 40 patients.

RESULTS

A total of 86 proteins were shown to be differentially abundant between the serum of SCLC patients and normal subjects by 2-D DIGE. Fifteen proteins were identified by LC-MS/MS. According to the bioinformatic analysis, these proteins are mainly involved in development and carcinogenesis. Some of them have been previously demonstrated to be important prognostic factors. Differential expression of 5 proteins between the normal tissue and cancerious tissue was confirmed by immunochemistry of SCLC patients.

CONCLUSION

We have identified different serum proteins between SCLC patients and healthy controls. These proteins may be potential serum biomarkers for early detection of SCLC and play a role in the development and metastasis of SCLC.

Herpes simplex virus vector-mediated gene transfer of kynurenine aminotransferase improves detrusor overactivity in spinal cord-injured rats

Detrusor overactivity threatens the renal function of patients with spinal cord injury. Suppressing N-methyl-D-aspartate receptors is known to improve detrusor overactivity in rats with spinal cord injury, whereas kynurenic acid, the endogenous antagonist of N-methyl-D-aspartate receptors, is irreversibly synthesized by kynurenine aminotransferases (KATs). In this study, we investigated whether replication-defective herpes simplex virus vector-mediated gene transfer of human KAT II could treat detrusor overactivity by injecting the vectors into the rat bladder wall 1 week after spinal cord injury. Three weeks after injection, we evaluated the cystometry and gene expression of KAT II in L6-S1 dorsal root ganglia. The results showed that the vectors are transported to L6-S1 dorsal root ganglia and upregulate the expression of KAT II, and that they also improve the detrusor overactivity and voiding efficiency. We also proved that N-methyl-D-aspartate receptors were blocked by kynurenic acid in the extracellular solution or the vector-mediated gene transfer of KAT II in cultured rat neurons of L6-S1 dorsal root ganglia by whole-cell patch clamp to explore the mechanisms of gene therapy. Therefore, replication-defective herpes simplex virus vector-mediated KAT II inhibits detrusor overactivity in spinal cord-injured rats, possibly by suppressing N-methyl-D-aspartate receptors in bladder afferent pathways.

Magnetic resonance imaging of bone and muscle traits at the hip: an in vivo precision study

OBJECTIVE

To determine the in vivo precision of MRI-based measures of bone and muscle traits at the hip.

METHODS

Left proximal femoral neck and shaft of 14 participants (5M:9 F; age:21-68) were scanned 3 times using a 1.5 T MRI. Commercial and custom image processing methods were used to derive bone geometry and strength traits at the proximal femoral neck and shaft along with muscle area of various muscle groups at the shaft site. For precision, root mean square coefficients of variation (CV%rms) and standard deviations (SDrms) were calculated.

RESULTS

At the femoral neck, CV%rms for area-based bone measures ranged between 1.7-5.0%; CV%rms for cortical thickness varied from 4.7 to 5.6%; and CV%rms for bending, torsional and buckling-based strength indices ranged between 4.6-7.1%. At the femoral shaft, CV%rms for bone area ranged between 1.2-3.0%; CV%rms for cortical thickness varied from 1.7 to 2.0%; and CV%rms for bending and buckling-based strength indices ranged between 1.4-3.1%. For muscle area, CV%rms ranged between 1.3-4.5%.

CONCLUSIONS

MRI-based measures of bone and muscle traits at the proximal femoral neck and shaft demonstrated in vivo precision errors <7.1%. MRI is a promising 3D technique for monitoring changes in bone and muscle at the clinically important hip.

Abstract P5-08-14: Deregulated histone and cell cycle pathways are associated with anthracycline resistance in breast cancer

Drug resistance in breast cancer is the major obstacle to a successful outcome following chemotherapy treatment. While a well-recognized mechanism of resistance involves upregulation of multidrug resistance (MDR) genes, the complexity and hierarchy of other non-MDR driven pathways are still largely unknown. The aim of this study was to identify pathways contributing to anthracycline resistance using isogenic drug resistant breast cancer cell lines. We generated MDA-MB-231, MCF7, SKBR3 and ZR-75-1 epirubicin-resistant breast cancer cell lines, all of which were cross-resistant to doxorubicin and SN-38; only SKBR3 cell line was also resistant to taxanes. Epirubicin-resistant cells were morphologically different from native cells, and had alterations in apoptosis and cell cycle profile. Using gene expression and small inhibitor analyses we identified deregulation of histone H2A and H2B genes in all four cell lines. These genes contribute to several biological pathways, which include cell cycle, chromosomal maintenance, epigenetics, RNA polymerase and mitochondrial transcription, as well as post-translational protein modifications. Importantly, histone deacetylase and cell cycle/DNA damage small molecule inhibitors reversed resistance and were cytotoxic for all four epirubicin-resistant cell lines confirming that histone and cell cycle pathways are associated with epirubicin resistance. Our study has established a model system for investigating drug resistance in all four breast cancer subtypes and revealed key pathways that contribute to the molecular mechanisms of anthracycline resistance.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-08-14.

Clinical study of a noninvasive multimodal sono-contrast induced spectroscopy system for breast cancer diagnosis

PURPOSE

To present a noninvasive multimodal sono-contrast induced spectroscopy (SCIS) system for breast cancer detection.

METHODS

An IRB approved clinical study was carried out to evaluate its diagnostic power. A total of 66 subjects were enrolled with informed consent. The study data were grouped into healthy breast tissue (26), histologically proven cancer (14), and benign mass (26). The diffuse reflectance optical intensity and low intensity focused ultrasound (LIFU) signals, as well as ultrasound images, were collected during each study. The ratio of optical intensities at wavelengths 685 and 830 nm was analyzed using wavelet technique to compare the LIFU effects in cancer and noncancerous tissues. The ultrasound images were also processed to obtain tissue texture parameters, such as correlation, energy, contrast, homogeneity, etc. Backward stepwise regression method was performed to identify the statistically significant factors correlating to tissue types (cancer vs benign mass).

RESULTS

Comparison of the optical signals showed that LIFU induced transitory fluctuation in noncancerous tissue, but not in malignant tissue, as quantified by the ratio of mean absolute deviation (RMAD) of the high frequency component. Statistical analysis revealed that the RMAD ratios were significantly different in tumor vs noncancerous masses (p ≪ 0.01). For tissue texture parameters, energy and correlation were found to statistically correlate with the tissue types. A cancer characterization model was developed using the weighted factors to differentiate the tumor from the benign mass. Trade-off between sensitivity and specificity was obtained by varying the threshold value that estimated the upper-bound of the cancer output factor, from which the receiver-operating characteristic (ROC) curve was generated. The characterization model was optimized using ten modeling datasets and verified using another ten validation datasets randomly generated from the database. The optimization results show that an AUC of 0.93 can be achieved. With threshold 0.3, sensitivity of 96.0%, specificity of 84.1%, and negative predictive value (NPV) of 97.3% can be achieved.

CONCLUSIONS

The feasibility of the multimodal system in characterizing breast cancer vs benign mass is established.