Abstract P5-04-18: Extracts derived from fungi and plants demonstrate specificity for subtyptes of triple negative breast cancer

New effective therapies are needed for patients with triple negative breast cancers (TNBC). The identification by Lehmann and Bauer1 of distinct subtypes of TNBC and representative cell lines that are driven by different defects and signaling pathways provided the opportunity, for the first time, to screen for selective activities against these subtypes of TNBC. Using this knowledge, we initiated a screen of diverse natural product extract libraries with the goal of identifying extracts selective for subtypes of TNBC. The compounds with this selective activity will then be purified using bioassay-guided fractionation. Drugs derived from plants and fungi have provided some of the most important pharmaceuticals used today, including numerous anticancer agents.2 Natural products occupy a biologically validated chemical space that does not overlap with compounds found in most synthetic chemical libraries.3 Additionally, there are differences in chemical space between plant and fungal-derived compounds4 and different compound classes are expected to be isolated from these two sources. A total of 1,953 extracts of fungi collected from diverse environments, including Great Lakes sediments and 2,200 plant extracts from tropical environments have been screened for selective cytotoxic activities against cell lines representing 5 subtypes of TNBC. These subtypes are the basal-like 1 and 2 (BL1, BL2), mesenchymal (M), mesenchymal stem-like (MSL) and luminal androgen receptor (LAR). The initial screening using one concentration, 2 µg/ml for fungal extracts and 20 µg/ml for plant extracts, identified many extracts with selective activity against the TNBC subtypes. Detailed dose response curves were then generated with these extracts in each of the TNBC cell lines. A total of 4 fungal extracts and 7 plant extracts with selective cytotoxic activities were identified with selectivity up to 100-fold for 3 of the extracts. Bioassay-guided fractionation is ongoing to identify the active constituents. These results demonstrate that natural product extracts can yield selective actions against TNBC subtypes. We expect that these plant and fungal extracts will yield compounds that target molecular drivers specific to the TNBC subtypes. It is our expectation that compounds with selective, targeted activities will continue to be isolated from these extract collections.

1. Lehman BD and Bauer JA et al. J Clin Invest: 121, 2750-2767, 2011.

2. Newman DJ and Cragg GM. J Nat Prod: 75, 311-335, 2012.

3. Feher M and Schmidt JM. J Chem Inf Comput Sci: 43, 218-227, 2003.

4. El-Elimat, T et al. ACS Med Chem Lett: 3, 645-649, 2012.

Citation Format: Shaffer CV, Cai S, Perez A, Risinger AL, Du L, O'Keefe BR, Cichewicz RH, Mooberry SL. Extracts derived from fungi and plants demonstrate specificity for subtyptes of triple negative 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 P5-04-18.

Abstract P3-06-04: Investigating clonal dynamics in triple negative breast cancer chemoresistance

Approximately 50% of triple-negative breast cancer (TNBC) patients have extensive residual disease following neoadjuvant chemotherapy (NAC). These patients have a four-fold increase in mortality risk and an increased risk of distant metastases within three years (1). Understanding the molecular basis of resistance to NAC is expected to provide opportunities to better treat patients in the primary setting. Extensive intratumoral subclonal heterogeneity has been well documented in primary, treatment-naïve TNBC (2). Subclonal populations harboring distinct molecular profiles may confound targeted therapy strategies, yet the functional impact of subclonal heterogeneity in TNBC resistance to therapy is unknown. We are implementing DNA barcoding to quantitatively track changes in subclonal architecture pre- and post-treatment in patient-derived xenograft (PDX) models of TNBC in order to design novel combination therapies. Such barcoding strategies have been used to monitor clonal dynamics in breast cancer PDXs with great sensitivity (3).

We have established an orthotopic PDX from a treatment-naïve TNBC patient (PIM1, procured from a patient later found to have chemoresistant disease). In order to model chemoresistance, we treated PIM1 with Adriamycin and cyclophosphamide (AC), standard of care NAC for TNBC patients, which resulted in partial response but left residual disease. To characterize subclonal dynamics in response to NAC, we transduced freshly isolated PIM1 cells with a lentiviral library expressing 25 million unique DNA barcodes (Cellecta) using conditions to ensure each transduced cell contained a single unique barcode. Transduced cells were selected with puromycin, then orthotopically implanted into immuno-compromised mice. High-throughput barcode sequencing revealed reproducible maintenance of greater than 60,000 unique barcodes in PDX tumors. Comparison of barcode distribution in tumors treated with vehicle or NAC will reveal whether NAC selects for a subpopulation of cells during the development of resistance. Future directions will include whole-exome and RNA sequencing to characterize genomic changes associated with alterations in barcode distribution in response to NAC treatment. Our ultimate goal is to identify novel combination therapies to eliminate subclones that contribute to chemoresistance in primary TNBC.

References

1. Cortazar P, et al. (Pathological complete response and long-term clinical benefit in breast cancer: the CTNeoBC pooled analysis. The Lancet 384(9938):164-172.

2. Shah SP, et al. (2012) The clonal and mutational evolution spectrum of primary triple-negative breast cancers. Nature 486(7403):395-399.

3. Nguyen LV, et al. (2014) DNA barcoding reveals diverse growth kinetics of human breast tumour subclones in serially passaged xenografts. Nat Commun 5.

Citation Format: Echeverria GV, Seth S, Moulder S, Symmans W, Chang J, Cai S, Heffernan T, Piwnica-Worms H. Investigating clonal dynamics in triple negative breast cancer chemoresistance. [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 P3-06-04.

Do the cations in clay and the polymer matrix affect quantum dot fluorescent properties?

This paper studied the effects of cations and polymer matrix on the fluorescent properties of quantum dots (QDs). The results indicated that temperature has a greater impact on fluorescence intensity than clay cations (mainly K(+) and Na(+) ). Combined fluorescence lifetime and steady-state spectrometer tests showed that QD lifetimes all decreased when the cation concentration was increased, but the quantum yields were steady at various cation concentrations of 0, 0.05, 0.5 and 1 M. Poly(ethylene oxide) (PEO), poly(vinyl alcohol) (PVA) and diepoxy resin were used to study the effects of polymers on QD lifetime and quantum yield. The results showed that the lifetime for QDs 550 nm in PEO and PVA was 17.33 and 17.12 ns, respectively; for the epoxy resin, the lifetime was 0.74 ns, a sharp decrease from 24.47 ns. The quantum yield for QDs 550 nm changed from 34.22% to 7.45% and 7.81% in PEO and PVA, respectively; for the epoxy resin the quantum yield was 2.25%. QDs 580 nm and 620 nm showed the same results as QDs 550 nm. This study provides useful information on the design, synthesis and application of QDs-polymer luminescent materials. Copyright © 2015 John Wiley & Sons, Ltd.

Cytotoxicity, genotoxicity and antibacterial effectiveness of a bioceramic endodontic sealer

AIM

To compare the characteristics of bioceramic endodontic sealer Endosequence BC sealer with those of AH Plus sealer.

METHODOLOGY

Cytotoxicity and genotoxicity were analysed on human gingival fibroblasts submitted to cell culture medium conditioned by sealers using the MTT reduction assay and micronucleus formation test (MNT), respectively. Cells grown on fresh medium served as controls. Cell viabilities were measured at 1, 3, 5 and 7 days. The antibacterial activity was analysed on an Enterococcus faecalis strain (ATCC 29212) using both on agar diffusion test (ADT) and a direct contact test (DCT). The inhibition zones in ADT were measured after 48 h and the colony-forming units counting in the DCT after 1, 24, 72 and 168 h. Data were compared by anova and Tukey's test and MNT by Fisher's exact test (P < 0.05).

RESULTS

Cultures submitted to Endosequence BC sealer had a significantly higher number of viable cells (P < 0.01) and less micronucleus formation (P < 0.05) than AH Plus sealer. Endosequence BC sealer exhibited significantly smaller inhibition zones (6.00 ± 0.03 mm) than AH Plus sealer (10.31 ± 0.21 mm) (P < 0.05). Moreover, Endosequence BC sealer had significantly smaller antibacterial activity than AH Plus sealer up to 1 h of direct contact (P < 0.05). On other exposure times, both materials had similar antibacterial effectiveness (P > 0.05).

CONCLUSIONS

Bioceramic-based sealer had less cytotoxicity and genotoxicity and similar antibacterial effect against E. faecalis in comparison with AH Plus sealer.

The prognostic value of pSTAT3 in gastric cancer: a meta-analysis

INTRODUCTION

The prognostic value of pSTAT3 in gastric cancer has been assessed for years while the results remain controversial and heterogeneous. Therefore, we conducted this meta-analysis to determine the prognostic effect of pSTAT3 in gastric cancer patients.

METHODS

We searched PubMed, Embase and Web of Science and eight studies comprising 1314 gastric cancer patients were included in our meta-analysis. Hazard ratios (HRs) with 95 % confidence interval (95 % CI) were extracted to perform meta-analysis on the overall survival. Subgroup analysis according to study location, publication year, number of patients and quality score of studies were also investigated.

RESULTS

Our results revealed that pSTAT3-positive patients had a significant increase in mortality risk as compared to pSTAT3-negative patients in the random-effects model (combined HR 1.87, 95 % CI 1.28-2.74). However, our result showed no statistically significant association between pSTAT3 and clinicopathological characteristics (TMN stage, lymph node metastasis, grade of differentiation, Lauren classification and distant metastasis) of gastric cancer.

CONCLUSION

In conclusion, our meta-analysis suggests that positive expression of pSTAT3 is associated with poor prognosis in gastric cancer patients.

Scoring Functions Based on Second Level Score for k-SAT with Long Clauses

It is widely acknowledged that stochastic local search (SLS) algorithms can efficiently find models for satisfiable instances of the satisfiability (SAT) problem, especially for random k-SAT instances. However, compared to random 3-SAT instances where SLS algorithms have shown great success, random k-SAT instances with long clauses remain very difficult. Recently, the notion of second level score, denoted as "score_2", was proposed for improving SLS algorithms on long-clause SAT instances, and was first used in the powerful CCASat solver as a tie breaker. In this paper, we propose three new scoring functions based on score_2. Despite their simplicity, these functions are very effective for solving random k-SAT with long clauses. The first function combines score and score_2, and the second one additionally integrates the diversification property "age". These two functions are used in developing a new SLS algorithm called CScoreSAT. Experimental results on large random 5-SAT and 7-SAT instances near phase transition show that CScoreSAT significantly outperforms previous SLS solvers. However, CScoreSAT cannot rival its competitors on random k-SAT instances at phase transition. We improve CScoreSAT for such instances by another scoring function which combines score_2 with age. The resulting algorithm HScoreSAT exhibits state-of-the-art performance on random k-SAT (k>3) instances at phase transition. We also study the computation of score_2, including its implementation and computational complexity.

The delayed massive hemorrhage after gastrectomy in patients with gastric cancer: characteristics, management opinions and risk factors

AIMS

This study was designed to investigate the clinical features of delayed massive hemorrhage (DMH) after gastrectomy in patients with gastric cancer (GC).

METHODS

This study retrospectively reviewed 1536 GC patients with major gastrectomy between 1998 and 2011. Based on the time onset of postoperative bleeding, patients were divided into early postoperative hemorrhage (EPH), delayed massive hemorrhage (DMH), and no-bleeding groups. Postoperative mortality, bleeding treatment, and risk factors of hemorrhage were explored.

RESULTS

In sum, 15 (0.9%) patients suffered from DMH, with three (20%) dead cases. None of 18 (1.2%) patients with EPH died, but there were three dead cases in no-bleeding group. DMH had more extra-intestinal bleeding (P = 0.037) than EPH. Angiographic embolization was performed in 12 (80%) of DMH patients and successful in ten cases. Surgical procedures were applied in only two embolization-failed cases. Extended lymphadenectomy (P = 0.038), vascular skeletonization (P = 0.012) and advanced TNM stage (P < 0.001) were correlated with DMH.

CONCLUSIONS

DMH can be successfully managed with angiographic embolization, followed by alternative surgery. Extensive lymphadenectomy and vascular skeletonization should be discreetly performed during gastrectomy.

The visual diagnosis of tuberculous pleuritis under medical thoracoscopy: a retrospective series of 91 cases

BACKGROUND

Despite progress of medical, the fast and accurate diagnosis of tuberculous pleuritis (TP) continues to be a challenge, mainly because of the lack of specific clinical features and the difficulty in isolating the Mycobacterium tuberculosis.

OBJECTIVES

To investigate the role of medical thoracoscopy in definite diagnosis of tuberculous pleuritis, especially the feature of visual diagnosis in tuberculous pleuritis via medical thoracoscopy. We performed a retrospective review of the utility of medical thoracoscopy in tuberculous pleuritis.

PATIENTS AND METHODS

A retrospective chart review was performed of 91 patients who had medical thoracoscopy for suspected TP at the Second Xiangya Hospital from October 1, 2006 to July 30, 2012.

RESULTS

In ninety one cases, 76 patients were diagnosed with TP by pathologic diagnosis. The visual findings via thoracoscopy of 76 TP patients included the following: (1) necrosis (76.32%, n=58), (2) diffuse miliary nodules (64.67%, n=49), (3) single or multiple pleural nodules (14.47%, n=11), (4) hyperemic, edematous and thickened pleura (56.58%, n=43), and (5) pleural adhesions or fibrotic septa (78.95%, n=60), and all of these samples had hydrothorax or loculated effusion. The diagnostic efficiency of visual diagnosis via medical thoracoscopy about tuberculous pleuritis was 93.41%. In the non-invasive test, ADA > 40 u/l with LDH > 200 u/l for TP showed relatively high sensitivity and specificity (73.68%, 80.00%, respectively).

CONCLUSIONS

TP presents a variety of scopic phenotypes under medical thoracoscopy. The experienced pulmonologists visually diagnose TP efficiently and directly via medical thoracoscopy. Medical thoracoscopy with combined biopsy is an accurate and safe method for diagnosing TP.

Abstract P1-07-05: The cell fate factor DACH1 represses YB-1-mediated oncogenic transcription and translation

The epithelial-mesenchymal transition (EMT) enhances cellular invasiveness and confers tumor cells with cancer stem cell like characteristics, through transcriptional and translational mechanisms. The mechanisms maintaining transcriptional and translational repression of EMT and cellular invasion are poorly understood. The Drosophila homologue of DACH1, the Dac gene is a key member of the retinal determination gene network that specifies organismal development. The dachshund (dac), eya1, eyes-absent (eya), twin of eyeless (toy), teashirt (tsh) and sinoculues (so) are expressed in progenitor cells, contributing to development of the eye and genitalia. Loss of DACH1 expression contributes to the expansion of neural progenitors, muscle satellite cell differentiation and breast cancer stem cells. In recent studies Dachshund repressed breast cancer stem cell expansion. DACH1 expression is reduced in a variety of human cancers including prostate, ovarian and human breast cancer.

Herein, the cell fate-determination factor Dachshund (DACH1), suppressed EMT via repression of cytoplasmic translational induction of Snail by inactivating the Y box-binding protein (YB-1). In the nucleus, DACH1 antagonized YB-1-mediated oncogenic transcriptional modules governing cell invasion. DACH1 blocked YB-1-induced mammary tumor growth and EMT in mice. In basal-like breast cancer (BLBC) the reduced expression of DACH1 and increased YB-1, correlated with poor metastasis free survival. The loss of DACH1 suppression of both cytoplasmic translational and nuclear transcriptional events governing EMT and tumor invasion may contribute to poor prognosis in BLBC.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-07-05.

Tumour diameter is a predictor of mesorectal and mesenteric lymph node metastases in anorectal melanoma

AIM

Anorectal melanoma is a rare neoplasm with poor prognosis. The aim of this study was to investigate what clinicopathological factors predict lymph node metastases and to investigate their association with survival.

METHOD

Patients undergoing surgery with curative intent for primary anorectal melanoma in Fudan University Shanghai Cancer Center between 1989 and 2011 were studied retrospectively. The associations between clinicopathological factors and lymph node metastases and prognosis were determined.

RESULTS

Forty-three patients underwent a potentially curative resection with a median follow-up of 20 months; the 5-year overall survival rate was 29.6% with median overall survival of 28 months. Tumour diameter > 3 cm was associated with mesorectal and mesenteric lymph node metastases (P = 0.013). Perineural invasion (hazard ratio 5.683; 95% CI 1.978-16.328; P = 0.001) was the only factor that independently predicted survival.

CONCLUSION

Tumour diameter was associated with mesorectal and mesenteric lymph node metastases; therefore, wide local excision may not be appropriate for surgery with curative intent for patients with a tumour diameter ≥ 3 cm. Perineural invasion was an important prognostic factor for anorectal melanoma.

NuMVC: An Efficient Local Search Algorithm for Minimum Vertex Cover

The Minimum Vertex Cover (MVC) problem is a prominent NP-hard combinatorial optimization problem of great importance in both theory and application. Local search has proved successful for this problem. However, there are two main drawbacks in state-of-the-art MVC local search algorithms. First, they select a pair of vertices to exchange simultaneously, which is time-consuming. Secondly, although using edge weighting techniques to diversify the search, these algorithms lack mechanisms for decreasing the weights. To address these issues, we propose two new strategies: two-stage exchange and edge weighting with forgetting. The two-stage exchange strategy selects two vertices to exchange separately and performs the exchange in two stages. The strategy of edge weighting with forgetting not only increases weights of uncovered edges, but also decreases some weights for each edge periodically. These two strategies are used in designing a new MVC local search algorithm, which is referred to as NuMVC. We conduct extensive experimental studies on the standard benchmarks, namely DIMACS and BHOSLIB. The experiment comparing NuMVC with state-of-the-art heuristic algorithms show that NuMVC is at least competitive with the nearest competitor namely PLS on the DIMACS benchmark, and clearly dominates all competitors on the BHOSLIB benchmark. Also, experimental results indicate that NuMVC finds an optimal solution much faster than the current best exact algorithm for Maximum Clique on random instances as well as some structured ones. Moreover, we study the effectiveness of the two strategies and the run-time behaviour through experimental analysis.

Comparison of the pharmacokinetics of imipenem after intravenous and intrathecal administration in rabbits

BACKGROUND

Intrathecal administration of antibiotics has potentially high effectiveness for the treatment for severe intracranial infections, particularly nosocomial meningitis. The use of intrathecal injection of antibiotics has been reported mostly in case reports. However, there is sparse data regarding the pharmacokinetics of antibiotics after intrathecal administration.

AIM

This study investigated whether intrathecal injection is an effective method for the administration of imipenem.

MATERIALS AND METHODS

The pharmacokinetics of imipenem after intrathecal and intravenous administration of 1:1 imipenem: cilastatin (IMI/CIL) to rabbits were compared.

RESULTS

The AUC0-t in the cerebrospinal fluid for intrathecal administration was approximately twice that of an equal dose of intravenous administration at doses of 0.35, 0.7, and 1.4 mg/kg. Brain concentrations of imipenem after intrathecal injection were three times greater than observed after intravenous injection and remained high for at least 8 hours post-injection. Elimination of imipenem after administration by either route was primarily via urine, but a transient surge of imipenem in bile and intestinal tissue was observed.

CONCLUSIONS

Results indicate that there is a clinical potential for intrathecally administered IMI/CIL. Further studies are warranted to investigate the potential for seizure and to assess the translatability of the rabbit model to human treatment.