P5-21-01: A Renewable Tissue Resource of Phenotypically Stable Human Breast Cancer Xenografts for Preclinical Studies

Introduction Translational breast cancer research is hampered severely by difficulties in obtaining and studying primary human breast tissue, and by the lack of in vivo preclinical models that accurately reflect patient tumor biology. These limitations are due, in part, to the fact that traditional immunocompromised mouse models are not generally permissive for growth. We sought to circumvent some of these limitations by transplanting and growing human mammary tumors in the mammary fat pad of SCID/Beige immunocompromised mice in the absence of exogenous human fibroblasts.

Aims and Methods To establish a set of stable human breast cancer xenografts for preclinical studies. Human breast cancer biopsies were received, minced into small fragments and then transplanted directly into “cleared” fat pads of recipient SCID/Beige immunocompromised mice. Transplanted fat pads were checked weekly. After initial tumor was palpated and harvested, tumor fragments were transplanted into new SCID/Beige hosts for subsequent transplant generations. Serial immunohistochemical evaluations were performed to confirm human origin and biomarker status. Analytical flow cytometry for evaluating expression of proposed “cancer stem cell” markers, and gene and protein expression analysis were carried out on all stable lines.

Results and Conclusions Xenograft lines were established directly from breast cancer patient samples, without intervening culture in vitro, using the epithelium-free mammary fat pad as the transplantation site. Of the conditions tested, xenograft take rate was highest in the presence of a low-dose estradiol pellet without exogenous human fibroblasts. Thirty six stably transplantable xenograft lines representing 27 patients were established, using pre-treatment, mid-treatment, and/or post-treatment samples. Most patients yielding xenografts were “triple-negative” (ER-PR-HER2−) (n=21), we were able to establish lines from three ER-PR-HER2+ patients, one ER+PR+HER2−, one ER+PR-HER2−and one “triple-positive” (ER+PR+HER2+) patients. Serially passaged xenografts show phenotypic consistency with the tumor of origin at the histopathology level, and remarkable stability across multiple transplant generations at both the genomic, transcriptomic, and proteomic levels. Of 27 lines evaluated fully, thirteen xenografts showed metastasis to the mouse lung. These models thus serve as a renewable, quality-controlled tissue resource, and should prove useful for preclinical evaluation of experimental therapeutics.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-21-01.

P1-04-09: Biphasic Effects of Docetaxel and Hedgehog Signaling Antagonists on Breast Cancer Tumor-Initiating Cells In Vivo

Recent data suggest the existence of a subset of breast cancer cells variously termed cancer stem cells, tumor-initiating, or tumor-propagating cells, that are capable of self-renewal and of regenerating tumors upon transplantation that are biologically consistent with the tumor of origin. These cells appear to be intrinsically resistant to systemic chemo- and radiation therapies and may therefore be responsible for treatment resistance, and disease recurrence. Several signal transduction networks have been implicated in normal and malignant stem cell self-renewal. These include those of the Hedgehog, Notch, Wnt, EGF, FGF families of ligands. Antagonists of these networks have become attractive targeted therapeutic agents. In this study, we evaluated two different Hedgehog signaling antagonists, one targeting Smoothened (the main membrane effector of activated signaling) and one targeting GLI1/2 (the two transcription factors mediating ligand response), for their ability to shrink patient-derived xenograft tumors and to affect the number or function of breast tumor-initiating cells in vivo. Both antagonists showed little effect as single agents, but could augment tumor shrinkage by docetaxel. However, these effects were only observed in those models showing evidence of canonical SMO/GLI-mediated signaling. In dilutional transplantation assays, both SMO or GLI targeted agents have a biphasic effect on the behavior of the tumor-initiating population such that large cell numbers yielded few tumors while intermediate cell numbers yielded tumors at a comparable rate as controls. These data suggest that combination therapy alters the functional state of stem cells in the context of larger cell numbers rather than targeting the tumor-initiating cell directly. These data therefore have significant relevance for the interpretation of ongoing clinical trials of hedgehog signaling inhibitors in solid tumors, including breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-04-09.

P4-01-07: Combining Hedgehog Inhibitor, GDC-0449 with Tamoxifen Overcomes Tamoxifen-Resistance in In-Vitro and In-Vivo Studies of Estrogen-Receptor Positive Breast Cancer

Aims: Approximately 30–40% of patients with estrogen receptor positive (ER+) invasive breast cancer relapse despite targeted endocrine therapy with tamoxifen. Dependency of ER+ breast tumors shifts from estrogen to alternative cell survival mechanisms aberrantly activated over time facilitating drug-resistance and survival. We have identified Hedgehog (Hhg) signaling pathway as one such alternative pathway of survival activated in ER+ tumors that are resistant to tamoxifen. We sought to determine if treating such tumors with Hhg inhibitor and tamoxifen would improve outcomes.

Methods: Using MCF7 cell lines that are either sensitive (parental) or resistant to tamoxifen (4-hydroxy tamoxifen resistant-OHTR) and other ER+ cell lines, expression of Hhg markers (SHH, PTCH, SMO, GLI1, GLI2 and GLI3) and Hhg targets (SNAIL, MYC, BMI1 and FOXM1) was analyzed by Real-time RT-PCR, Western blotting and immunocytochemistry. GLI1 transactivation potential was measured using 8XGLI-Luciferase reporter plasmid. GLI1 was depleted in OHTR and T47D cells using GLI1siRNA. The GLI1 depleted cells were exposed to tamoxifen and assessed for i) cell viability by MTT assay, ii) extent of apoptosis by TUNEL assay and PARP/Caspase cleavage (Western blot), iii) cell cycle profile by flow cytometry and iv) presence of tumor initiating cells (TICs) by mammosphere formation assay. Effect of GDC-0449, a small molecule inhibitor of SMO was tested on OHTR cell induced xenografts in athymic nude mice by monitoring tumor growth and distant metastasis. Correlation of GLI1 expression in primary breast tumor tissues (assessed by immunohistochemistry) and disease-free interval was studied in women enrolled on an ongoing clinical trial (OSU 0483) in premenopausal women with ER+ breast cancer undergoing adjuvant oophorectomy and tamoxifen.

Results: Expression of Hhg signaling molecules and the targets are significantly activated in OHTR cells resistant to 0.5 and 1μM tamoxifen. Serial passage of the resistant cells in mice resulted in aggressive transformation of tumors that micro-metastasized to lung and liver. Concurrent increase in Hhg marker expression, TICs and acquisition of epithelial mesenchymal transition were observed in the cells derived from these tumors. Depletion of GLI1 in OHTR cells resulted in reduced proliferation, colony formation and mammosphere formation and increased apoptosis in presence of tamoxifen. Treatment of OHTR cells with GDC-0449 and tamoxifen inhibited cell proliferation in vitro and supressed tumor growth and distant metastasis of tamoxifen resistant xenografts in mice. Primary human breast tumors expressing higher level of GLI1 demonstrated a trend towards increased risk of recurrence (p= 0.08) after tamoxifen therapy.

Conclusions: Our work has demonstrated for the first time that activated Hhg signaling is an alternate survival mechanism for tamoxifen resistant breast cancer. Furthermore, targeting these tumors with a combination of tamoxifen and anti-Hhg therapy inhibited tumor growth and development of distant metastases demonstrating efficacy of this approach. Clinical trials using this combination in patients with advanced ER+ breast cancer are warranted and are under development.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-01-07.

Isolation and characterization of nucleotide-binding site and C-terminal leucine-rich repeat-resistance gene candidates in bananas

Commercial banana varieties are highly susceptible to fungal pathogens, as well as bacterial pathogens, nematodes, viruses, and insect pests. The largest known family of plant resistance genes encodes proteins with nucleotide-binding site (NBS) and C-terminal leucine-rich repeat (LRR) domains. Conserved motifs in such genes in diverse plant species offer a means for the isolation of candidate genes in banana that may be involved in plant defense. Six degenerate PCR primers were designed to target NBS and additional domains were tested on commercial banana species Musa acuminata subsp malaccensis and the Musa AAB Group propagated in vitro and plants maintained in a greenhouse. Total DNA was isolated by a modified CTAB extraction technique. Four resistance gene analogs were amplified and deposited in GenBank and assigned numbers HQ199833-HQ199836. The predicted amino acid sequences compared to the amino acid sequences of known resistance genes (MRGL1, MRGL2, MRGL3, and MRGL4) revealed significant sequence similarity. The presence of consensus domains, namely kinase-1a, kinase-2 and hydrophobic domain, provided evidence that the cloned sequences belong to the typical non-Toll/interleukin-1 receptor-like domain NBS-LRR gene family.

High glucose-induced expression of inflammatory cytokines and reactive oxygen species in cultured astrocytes

Astrocyte activation plays important roles both in physiological and pathological process in the CNS. In the latter, the process is further aggravated by hyperglycemia, leading to diabetes complications of CNS. We report here that high glucose (HG) treatment stimulated astrocytic morphological alteration coupled with changes in glial fibrillary acidic protein (GFAP) and vimentin expression. Additionally, HG upregulated the expression of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), interleukin-4 (IL-4), and vascular endothelial growth factor (VEGF); however, its effects on transforming growth factor-β (TGF-β) expression were not evident. HG treatment induced increased production of reactive oxygen species (ROS) as well as activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator transcription 3 (STAT 3). HG-induced expression of TNF-α, IL-6, IL-1β, IL-4, and VEGF was blocked by ROS scavenger and inhibitors specific for NF-κB and STAT 3, respectively. The results suggest that the aforementioned multiple inflammatory cytokines and mediators that may be linked to the pathogenesis of the diabetes complications of CNS are induced by HG via the key signaling pathways.

Bronchopulmonary infection with Lophomonas blattarum: a case report and literature review

Human infection with Lophomonas blattarum is extremely rare. The clinical manifestations of 45 cases of bronchopulmonary L. blattarum infection occurring in China, including one case diagnosed and treated at the authors' hospital, are described. The most common manifestations included fever, cough with expectoration, chest stuffiness or shortness of breath, bronchiectasis and pulmonary abscess. A course of metronidazole treatment lasting 14-38 days was effective in controlling the disease. The diagnosis of L. blattarum infection should be based on one or more of bronchoscopic brush smear, bronchoscopic biopsy smear and bronchoalveolar lavage.

Comparison of entecavir and lamivudine in preventing hepatitis B reactivation in lymphoma patients during chemotherapy

During chemotherapy for lymphoma, the administration of cytotoxic agents and rituximab often results in hepatitis B reactivation (incidence, 14-72%). This study was designed to compare the efficacy of entecavir and lamivudine in preventing hepatitis B reactivation in lymphoma patients. Between January 2007 and February 2009, patients treated in four hospitals in China were screened to identify those most appropriate for analysis. These patients received either entecavir or lamivudine during chemotherapy and for 6 months after completion of chemotherapy. A total of 34 patients received entecavir and 89 patients received lamivudine. Compared with the lamivudine group, the entecavir group had significantly lower rates of hepatitis (5.9 vs 27.0%, P = 0.007), hepatitis B reactivation (0 vs 12.4%, P = 0.024) and disruption of chemotherapy (5.9 vs 20.2%, P = 0.042). All patients with hepatitis B reactivation had B-cell non-Hodgkin's lymphoma (stage III-IV). In lymphoma patients under chemotherapy treatment, entecavir is more effective than lamivudine in preventing hepatitis B reactivation. For patients with advanced stage disease, entecavir should be considered the primary preventive therapy.

A functional alternative splicing mutation in human tryptophan hydroxylase-2

The brain serotonergic system has an essential role in the physiological functions of the central nervous system and dysregulation of serotonin (5-HT) homeostasis has been implicated in many neuropsychiatric disorders. The tryptophan hydroxylase-2 (TPH2) gene is the rate-limiting enzyme in brain 5-HT synthesis, and thus is an ideal candidate gene for understanding the role of dysregulation of brain serotonergic homeostasis. Here, we characterized a common, but functional single-nucleotide polymorphism (SNP rs1386493) in the TPH2 gene, which decreases efficiency of normal RNA splicing, resulting in a truncated TPH2 protein (TPH2-TR) by alternative splicing. TPH2-TR, which lacks TPH2 enzyme activity, dominant-negatively affects full-length TPH2 function, causing reduced 5-HT production. The predicted mRNA for TPH2-TR is present in postmortem brain of rs1386493 carriers. The rs13864923 variant does not appear to be overrepresented in either global or multiplex depression cohorts. However, in combination with other gene variants linked to 5-HT homeostasis, this variant may exhibit important epistatic influences.

The prevalence and incidence of sick building syndrome in Chinese pupils in relation to the school environment: a two-year follow-up study

There are few incidence studies on sick building syndrome (SBS). We studied two-year change of SBS in Chinese pupils in relation to parental asthma/allergy (heredity), own atopy, classroom temperature, relative humidity (RH), absolute humidity (AH), crowdedness, CO₂, NO₂, and SO₂. A total of 1993 participated at baseline, and 1143 stayed in the same classrooms after two years. The prevalence of mucosal and general symptoms was 33% and 28% at baseline and increased during follow-up (P < 0.001). Twenty-seven percent reported at least one symptom improved when away from school. Heredity and own atopy were predictors of SBS at baseline and incidence of SBS. At baseline, SO₂ was associated with general symptoms (OR=1.10 per 100 μg/m³), mucosal symptoms (OR=1.12 per 100 μg/m³), and skin symptoms (OR=1.16 per 100 μg/m³). NO₂ was associated with mucosal symptoms (OR=1.13 per 10 μg/m³), and symptoms improved when away from school (OR=1.13 per 10 μg/m³). Temperature, RH, AH, and CO₂ were negatively associated with prevalence of SBS. Incidence or remission of SBS was not related to any exposure, except a negative association between SO₂ and new skin symptoms. In conclusion, heredity and atopy are related to incidence and prevalence of SBS, but the role of the measured exposures for SBS is more unclear.

PRACTICAL IMPLICATIONS

We found high levels of CO₂ indicating inadequate ventilation and high levels of SO₂ and NO₂, both indoors and outdoors. All schools had natural ventilation, only. Relying on window opening as a tool for ventilation in China is difficult because increased ventilation will decrease the level of CO₂ but increase the level of NO₂ and SO₂ indoors. Prevalence studies of sick building syndrome (SBS) might not be conclusive for causal relationships, and more longitudinal studies on SBS are needed both in China and other parts of the world. The concept of mechanical ventilation and air filtration should be introduced in the schools, and when planning new schools, locations close to heavily trafficked roads should be avoided.

Association analysis between the -2518MCP-1(A/G) polymorphism and generalized aggressive periodontitis in a Chinese population

BACKGROUND AND OBJECTIVE

It has been suggested that aggressive periodontitis has a genetic basis. Monocyte chemoattractant protein 1 (MCP-1) plays a critical role in the recruitment of monocytes and the development of periodontitis. The -2518MCP-1(A/G) polymorphism has been implicated as a risk or susceptibility factor for a variety of autoimmune conditions and inflammatory diseases. The intent of this investigation was to study whether the -2518MCP-1(A/G) polymorphism is associated with generalized aggressive periodontitis in the Chinese population.

MATERIAL AND METHODS

One hundred and twenty-four patients with generalized aggressive periodontitis and 94 healthy subjects were included in this case-control study. Genomic DNA was isolated from a peripheral blood sample obtained from each subject. Gene polymorphisms of -2518MCP-1(A/G) were analyzed by a standard polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. A logistic regression analysis was performed to test the association between the -2518MCP-1(A/G) genotype (alleles) and generalized aggressive periodontitis with adjustment of the major covariates (gender, age and smoking status).

RESULTS

There was no significant association of the -2518MCP-1(A/G) polymorphism with generalized aggressive periodontitis in the unstratified subjects. However, when patients were stratified by gender, the frequency of the G(+) genotype was significantly lower in female patients with generalized aggressive periodontitis compared with female controls (p = 0.036, adjusted odds ratio = 0.3, 95% CI: 0.1-0.9). In female patients with generalized aggressive periodontitis, the probing pocket depth was larger in subjects with the AA genotype than in subjects with the G(+) genotype (5.07 mm vs. 4.30 mm; Z = -2.470, p = 0.014).

CONCLUSION

The polymorphisms of -2518MCP-1 may play an important role in determining generalized aggressive periodontitis susceptibility in this cohort of Chinese women.

WNK4 inhibits NCC protein expression through MAPK ERK1/2 signaling pathway

WNK [with no lysine (K)] kinase is a subfamily of serine/threonine kinases. Mutations in two members of this family (WNK1 and WNK4) cause pseudohypoaldosteronism type II featuring hypertension, hyperkalemia, and metabolic acidosis. WNK1 and WNK4 were shown to regulate sodium chloride cotransporter (NCC) activity through phosphorylating SPAK and OSR1. Previous studies including ours have also shown that WNK4 inhibits NCC function and its protein expression. A recent study reported that a phorbol ester inhibits NCC function via activation of extracellular signal-regulated kinase (ERK) 1/2 kinase. In the current study, we investigated whether WNK4 affects NCC via the MAPK ERK1/2 signaling pathway. We found that WNK4 increased ERK1/2 phosphorylation in a dose-dependent manner in mouse distal convoluted tubule (mDCT) cells, whereas WNK4 mutants with the PHA II mutations (E562K and R1185C) lost the ability to increase the ERK1/2 phosphorylation. Hypertonicity significantly increased ERK1/2 phosphorylation in mDCT cells. Knock-down of WNK4 expression by siRNA resulted in a decrease of ERK1/2 phosphorylation. We further showed that WNK4 knock-down significantly increases the cell surface and total NCC protein expressions and ERK1/2 knock-down also significantly increases cell surface and total NCC expression. These data suggest that WNK4 inhibits NCC through activating the MAPK ERK1/2 signaling pathway.

Variation in sequence and expression of the avian FTO, and association with glucose metabolism, body weight, fatness and body composition in chickens

OBJECTIVE

The fat mass and obesity-associated gene (FTO), a crucial gene that affects human obesity and metabolism, has been widely studied in mammals but remains poorly characterized in birds. We aimed to identify variant FTO transcripts in domestic avian species, and to characterize the expression and biological functions of FTO in chickens.

METHODS

Variant FTO transcripts and their expression in birds were investigated using RACE and real-time quantitative reverse transcriptase-PCR technology. The effects of FTO on glucose metabolism, growth and body composition were determined by fasting and various diet treatments, as well as association analysis in a F₂ resource population. The function of cFTO1 was further studied by overexpression in chick embryo fibroblast (CEF) cells.

RESULTS

Variant FTO transcripts were identified in chicken (cFTO1 to cFTO4), duck (dFTO1, dFTO2 and dFTO4) and goose (gFTO1, gFTO2 and gFTO5). In the chicken, the complete transcript (cFTO1) was predominantly expressed in the leg muscle, pituitary, hypothalamus and cerebellum. Fasting increased both cFTO1 and PGC1α gene expression in the cerebrum, liver, breast muscle and subcutaneous fat, but decreased expression in the pituitary and anterior hypothalamus. In all tested tissues in chickens, a high-glucose diet markedly increased cFTO1 and PGC1α expression. Feeding a high-fat diet increased both cFTO1 and PGC1α expression, except in the pituitary. Overexpression of cFTO1 in CEF cells significantly increased the expression of PGC1α (2.5-fold), STAT3 (2.2-fold) and HL (1.5-fold), a cluster of genes related to energy metabolism. A total of 65 single nucleotide polymorphisms (SNPs) were identified in chicken FTO, and 18 tested SNPs were significantly associated with traits of body weight, body composition and fatness.

CONCLUSIONS

These data collectively indicate that FTO is related to glucose metabolism, body weight, fatness and body composition in birds, thus expanding knowledge of FTO function to non-mammalian species.

Dosimetric variations of target volumes and organs at risk in nasopharyngeal carcinoma intensity-modulated radiotherapy

OBJECTIVE

The aim of this study was to evaluate the actual dose variability to the targets and organs at risk (OARs) during nasopharyngeal carcinoma (NPC) intensity-modulated radiotherapy (IMRT) and to investigate the significance of replanning.

METHODS

11 NPC patients were included in this study. Each patient had both a planning CT and weekly repeated CT. Simulated plans that were generated by using the same beam configurations mapped to the repeated CT represented the actual delivered doses to the target volumes and OARs. An IMRT replanning was performed with the fifth week CT scan. Doses among the initial plan, the simulated plans and replanning were compared.

RESULTS

There were no significant dosimetric differences in the gross tumour volume, clinical target volume (CTV) 1 or CTV2 for either the simulated plans or the replanning compared with the initial plan. Dosimetric variability of both parotid glands and the brain stem were unique to each individual, and doses to the spinal cord were always maintained within the limit. Replanning in the fifth week had significantly decreased the doses delivered to both parotids (p-values of the mean dose were 0.015 and 0.026 for the left and right parotid, respectively), whereas it did not reduce the doses to the brain stem and spinal cord. There was no relationship between dose variability and weight loss.

CONCLUSIONS

There are no significant dose changes for target volumes and spinal cord, and doses to the brain stem and both parotid glands changed individually during NPC IMRT. Replanning helps to spare bilateral parotids.

Change in mortality risk over time in young kidney transplant recipients

Mortality risk for kidney transplant recipients may change with increasing accumulated exposure to the "transplantation milieu." We sought to characterize changes over time in mortality rate and in age-, sex- and race-standardized mortality ratios (SMR) relative to the general population, and to estimate the association between increasing time since first transplant and mortality risk. A total of 18 911 patients who received a first transplant at <21 years old (1983-2006), and whose data were recorded in the USRDS, were studied. There were 2713 deaths over a median follow-up of 8.9 (interquartile range 4.0-14.5; maximum 23) years. Among those with graft function, mortality was highest in the first post transplant year; beyond the first year of the first transplant, age-adjusted mortality rates and SMRs decreased slightly over follow-up. Cause of death was cardiovascular for 34.6%, infection for 19.5%, malignancy for 5.8%, other for 21.4% and unknown for 18.7%. For every 1-year time increment after the end of the first post transplant year, age-adjusted all-cause and cardiovascular mortality rates fell by 1% (p = 0.06) and 16% (p = 0.007), respectively; infection-related mortality rate did not change over time (p = 0.5). These results suggest that exposure to the transplantation milieu has no cumulative negative effects on cardiovascular health over the long term.

Stability and nonlinear optical properties of ZnO nanoparticles

Photoluminescence (PL) of ZnO nanoparticles of different surface states and sizes grown by several methods has been measured. The origin of luminescence and dependence of the luminescence spectrum shape and intensity on 325 nm excitation laser power are studied. Strong ultraviolet emission at 3.26 eV, weak violet emission around 3.12 eV and weak green emission at 2.40 eV have been observed in 16 nm nanoparticles capped by octylamine grown by non-hydrolytic method. The nanoparticles are stable under high power laser radiation and their PL intensity increases nonlinearly with an increasing laser power. As the nanoparticle size decreases to 12 nm, high power laser produces nonradiative centers which may quench the luminescence in a degree. Nanoparticles of 8 nm capped by PVP and uncapped nanoparticles of 14 nm are unstable and their luminescence depends on the excitation laser power. High power laser can quench O vacancy emission and enhance ultraviolet emission in PVP capped nanoparticles while vacancy emission can not be quenched in uncapped nanoparticles.