Abstract P5-09-05: Progranulin (GP88) expression and letrozole resistance in breast cancer

The 88 kDa glycoprotein GP88 (Progranulin, PCDGF, acrogranin) is the largest member of the granulin/epithelin family of growth modulators. GP88 was originally characterized in our laboratory through a biological screen to identify drivers of tumorigenesis. Published studies have established that GP88 represents an ideal therapeutic and diagnostic target in breast cancer (BC) leading to the development of validated tools to measure GP88 in tumor biopsies and biological fluids as well as blocking its action. It was shown that: 1) GP88 expression increases with tumorigenesis; 2) in ER+ breast cancer cells, GP88 stimulates proliferation and its overexpression confers estrogen independence and resistance to several anti-estrogens and aromatase inhibitor; 3) inhibition of GP88 expression by antisense transfection inhibited proliferation in vitro and in vivo; 4) In Her-2 overexpressing breast tumors, GP88 stimulated Her-2 phosphorylation and conferred trastuzumab resistance; 5) GP88 is expressed in 80% invasive ductal carcinoma (IDC) and 60% of ductal carcinoma whereas it is negative in lobular carcinoma, benign lesions and normal mammary tissues; 6) GP88 is secreted and can be detected in the serum of BC patients at an increased level when compared to healthy subjects; 7) Pathological studies with 530 cases of ER+ IDC with clinical outcomes showed that GP88 tumor expression was an independent prognostic indicator of recurrence in early stage BC patients. Training study followed by an independent validation study demonstrated that high GP88 tissue expression (GP88 3+) was associated with a 4-fold increase in risk of recurrence at 5 years.

Since GP88 displays not only diagnostic but also therapeutic potentials, we developed a neutralizing anti-GP88 antibody AG1 that inhibited GP88 biological effect (proliferation and migration) in a dose-dependent fashion in vitro. AG1 was expressed in a high yield CHO cell line and formulated. We have shown that in tamoxifen resistant cells, treatment with AG1 would inhibit tumor growth and restore tamoxifen sensitivity. The present study examined the effect of AG1 in letrozole resistant cells. We have developed from a letrozole sensitive cell ER+ BC cell line, a letrozole-resistant cell line by long term selection in letrozole-supplemented medium. This cell line (LetR) shows also decreased letrozole responsiveness in vivo and therefore constitutes an excellent model for investigating letrozole resistance in vivo as well as in vivo. Here we investigated the effect of various doses of AG1 on LetR tumor development alone or in combination with letrozole. Treatment with AG1 (10 mg/kg i.p.) in combination with letrozole was efficient to maintain long term responsiveness to letrozole and inhibited tumor growth. In addition to the mouse xenografts study, an IRB approved clinical study examines changes in GP88 circulating levels in patients with resistance to aromatase inhibitors. Preliminary data will be presented.

In conclusion, inhibiting GP88 could provide a novel and alternative therapeutic strategy for patients with resistance to anti-estrogen therapy, being tamoxifen or letrozole.

This work is supported by 2R44CA124179 and HHSN 261201200060C from NCI and 02- 2013-018 from the Avon Foundation for Women.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-09-05.

Abstract P2-10-40: Correlation between expression of the prognostic marker Progranulin (GP88) with Oncotype Dx Recurrence Score in estrogen receptor positive breast tumors

Background: GP88 (Progranulin, acrogranin) is an 88kDa glycoprotein overexpressed in breast tumors and involved in their proliferation and survival. Biological studies have shown that GP88 in ER+ breast cancer cells was associated with estrogen independence and resistance to anti-estrogen therapies and aromatase inhibitors. In addition, GP88 stimulated migration, invasion and angiogenesis, hallmarks of metastasis. Pathological studies have demonstrated that GP88 was preferentially expressed in invasive ductal carcinoma while lobular carcinoma was mostly negative. No expression was found in normal mammary tissue. Two retrospective studies totaling 530 cases of ER+ formalin-fixed paraffin-embedded invasive ductal carcinoma (IDC) established that high GP88 expression was associated with a 4-fold increase in risk of recurrence and 2.5-fold increase in death when compared to low GP88 scores. Multivariate analysis showed that GP88 remains a predictor of recurrence even when adjusted for prognostic factors such as tumor size, grade, stage, lymph node status and age. High level of GP88 was also found to be elevated in the serum of breast cancer patients when compared to healthy individuals. Since GP88 tumor tissue expression appears as a prognostic factor for ER+ breast cancer, we proposed to investigate whether GP88 tumor tissue expression would correlated to Oncotype Dx® Recurrence Score which is now for early stage ER+ node negative breast cancer patients.

Methods: Eight five cases from women ages 37–77 with ER+ invasive mammary carcinoma from three different institutions and with an available Oncotype Dx recurrence score were selected with approval from each site's IRB. GP88 expression was determined by immunohistochemistry (IHC) using the anti-human GP88 6B3 monoclonal antibody (A&G) on a Ventana automated staining platform. For all cases examined, GP88 IHC scores (0, 1+, 2+, 3+) were compared to routine clinicopathologic factors (tumor size, grade, and stage), PR, HER2/neu and Ki67 expression (by image analysis) and to their Oncotype DX® recurrence score (Genomic Health). The associations of GP88 with the parameters described above were assessed by t test or ANOVA.

Results: The GP88 tissue expression correlated with Oncotype Dx Recurrence score (p < 0.03) as well as with Ki-67 index (p < 0.004). Age, HER2/neu and PR status did not correlate with GP88 expression. Details of these finding will be presented here.

Conclusion: This study shows that GP88, an important tumor aggressiveness indicator, significantly correlates with Oncotype DX score and confirms that GP88 correlates with other tumor clinicopathologic parameters and prognostic markers. Further studies are underway to determine whether GP88 in combination with routine markers, particularly Ki67, could be used instead of Oncotype DX Assay to predict outcome and provide information for the management of ER+ breast cancer patients.

This study is supported by grant 02–2010-010 from the Avon Foundation for Women.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-10-40.

P2-12-32: Association between Progranulin (GP88) Expression and Recurrence Risk for Breast Cancer Patients with Estrogen Receptor Positive Invasive Ductal Carcinoma

Purpose: GP88 (progranulin) is a critical player of breast tumorigenesis for estrogen receptor positive (ER+) breast cancer. Pathological studies showed that GP88 was expressed in invasive ductal carcinoma (IDC), but not in normal mammary tissue, benign lesions or lobular carcinoma. The present study examines GP88 prognostic significance in association with recurrence risk for patients with ER+ IDC.

Patients and Methods: Two retrospective multi-site clinical studies examined GP88 expression by immunohistochemistry (IHC) analysis in paraffin-embedded tumor tissues in correlation with patients’ survival outcomes. The training study established a GP88 cut-off value associated with decreased disease-free (DFS) and overall (OS) survivals. The validation study verified the GP88 cut-off value and compared GP88 prognostic information with other prognostic factors in multivariate analysis.

Results: GP88 expression is associated with a statistically significant increase in recurrence risk for ER+ IDC patients. The training study established that GP88 3+ score by IHC analysis was associated with decreased DFS (p=0.0004) and OS (p=0.0036). The independent validation study verified that GP88 3+ score for the high risk group and demonstrated that GP88 3+ score was associated with a 5.9-fold higher hazard of disease recurrence and a 2.5-fold higher mortality hazard compared to patients with tumor GP88<3+. GP88 remained an independent risk predictor after considering age, nodal status, tumor size, tumor grade, progesterone receptor expression, treatment and disease stage.

Conclusion: Our training and validation studies demonstrate that the survival factor GP88 is a prognostic biomarker, predictive of recurrence risk and increased mortality for ER+ IDC patients, independent from other prognostic factors. These results provide support for measuring GP88 tissue expression for newly diagnosed early stage breast cancer patients.

This work was supported by grants R43CA124179, and U01CA113916 from the National Cancer Institute, grants 07-2007-064 and 02-2010-010 from the Avon Foundation for Women.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-12-32.

Isolation and characterization of twelve polymorphic microsatellite loci in the buff-throated partridge (Tetraophasis szechenyii)

Twelve polymorphic microsatellite markers were isolated from an AC-enriched genomic library of Buff-throated partridge (Tetraophasis szechenyii). The allele number of these loci ranged from three to 13 (average 7.75 per locus) in tested individuals. Polymorphism information content ranged from 0.532 to 0.882 with an average of 0.721. Average observed and expected heterozygosities were 0.559 (range from 0.240 to 0.792) and 0.772 (range from 0.621 to 0.910), respectively. These microsatellite markers will be useful for the assessment of genetic diversity, relatedness identification of family and analysis of population structure in wild buff-throated partridge.

GP88 Serum Level Is Increased in Breast Cancer Patients with Disease Progression

GP88 (progranulin) is an 88-kDa glycoprotein autocrine growth factor that plays a critical role in breast tumorigenesis. GP88 is expressed in human BC tumors in a positive correlation with their tumorigenicity. In estrogen receptor positive (ER+) cells, GP88 expression is low and is stimulated by estradiol whereas in ER negative (ER-) cells, it is constitutively overexpressed. In ER+ cells, increased GP88 expression was found to be associated with resistance to anti-estrogen therapy. In Her-2 overexpressing breast tumors, increased GP88 expression was associated with Herceptin resistance. Inhibition of GP88 expression in human breast adenocarcinoma cells resulted in a drastic reduction of tumor incidence and tumor growth in nude mice. Immunohistochemical studies carried out with 206 paraffin-embedded human breast biopsies have shown that GP88 is expressed in invasive ductal carcinomas in correlation with expression of markers of poor prognosis whereas normal tissues and benign breast lesions were negative. Importantly, high GP88 expression in tissue biopsies was accompanied by decreased disease-free and overall survival. Since GP88 contains a signal peptide for secretion, we have shown that GP88 can be found in serum. An IRB approve blood sampling study of 189 patients (Race: Caucasian- 91, African American-92, Asian-6; median age- 51 with a range from 26 to 81) established at the University of Maryland demonstrated that GP88 was measurable in serum and that GP88 serum level was statistically elevated in breast cancer patients when compared to healthy individuals. Median level of GP88 was 40.7 ng/ml (range 6.4-80) in early stage (stage 1 –3) BC pts (p- value = 0.007) and 45.3 ng/ml (range 9.8 to 158.4) in stage 4 metastatic BC patients (p-value= 0.0007). Statistically significant increase in circulating GP88 level was found in early stages as well as in metastatic disease when compared to healthy individuals.Since we have shown that GP88 tissue expression was associated with increased disease recurrence, the present study was focused on examining whether GP88 serum level was also increased in disease progression and could be used to monitor disease recurrence. Our data show that patients with disease recurrence or progression presented a 5 to 10 fold increase in their GP88 serum levels.This study identifies GP88 as a measurable biomarker for recurrence or disease progression not only at the tissue but also at the serum level.This study is supported by grants from MIPS, the Avon Foundation and from the National Cancer Institute.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6040.

Cellular deposits on intraocular lenses

We examined cellular deposits on 14 intraocular lenses (IOL) that were removed after implantation for a variety of clinical reasons. Five of the lenses were cultured to evaluate the growth potential of preexisting cells on the IOLs. The most common cells found were iris pigment epithelial cells. The thickest membranes were probably formed by iris stromal cells. Other cellular deposits included macrophages, multinucleated foreign body giant cells, lens epithelial cells, squamous epithelial ingrowth, red blood cells, uveal melanocytes, and vitreous strands. Cells around the IOL had only limited growth in tissue culture. We propose that a continuous influx of inflammatory cells in conjunction with a disruption of the blood-aqueous barrier may be an important pathogenetic mechanism for the production of thick secondary membranes around an IOL.

Association of serum levels of the growth factor GP88 with disease progression in breast cancer patients

e22021

Background: The autocrine growth factor GP88 is an important player in breast cancer. GP88 is expressed in human BC tumors in correlation with their tumorigenicity. Increased GP88 expression was associated with anti-estrogen therapy resistance in ER+ cells and Herceptin resistance in Her-2 overexpressing breast tumors. Inhibition of GP88 expression inhibited tumor incidence and growth in nude mice. Immunohistochemical studies have shown that GP88 is expressed in invasive ductal carcinomas (IDC) and that high GP88 expression correlated with increased recurrence and mortality. Since GP88 is found in serum, we hypothesized that GP88 was elevated in the sera of breast cancer patients compared to healthy individuals and that GP88 serum level increases with disease progression. Methods: An IRB approved prospective study was established at the University of Maryland Breast Clinic to determine the serum level of GP88 in breast cancer patients (BC pts). Approximately 5 ml of blood was drawn every three months. GP88 serum concentration was determined in triplicate by human GP88 enzyme immunoassay. 190 BC pts were accrued. Sera from healthy volunteers (HV) were obtained to establish GP88 baseline. BC patient characteristics: Caucasian- 91, African American-92, Asian-6; median age, 51 (range 29- 86), stage I - 48, II - 52, III - 26, IV - 63. Results: Median serum GP88 level was 28.7 ng/ml (range 16.6–38.2) in HV, 40.7 ng/ml (range 6.4–100) in early stage (stage 1 -3) BC pts (p- value = 0.007) and 45.3 ng/ml (range 9.8 to 158.4) in stage 4 BC patients (p- value= 0.0007). Statistically significant increase in serum GP88 level was found in early stages as well as in metastatic disease when compared to HV. In addition, patients that were initially diagnosed with early stage disease but recurred showed a 5 to 10 fold increase in their GP88 serum levels. Conclusions: GP88 serum level is significantly higher in the sera of BC than HV subjects. Moreover, GP88 serum level increased in association with disease recurrence and progression. This study identifies GP88 as a measurable biomarker for disease progression not only at the tissue but also at the serum level. These results are also interesting since GP88 is also a therapeutic target of malignant progression of breast carcinoma.

No significant financial relationships to disclose.

Elevated serum levels of the growth factor GP88 are found in breast cancer patients when compared to healthy individuals

Abstract #2006

Background: GP88 is an autocrine growth factor that plays a critical role in breast tumorigenesis. GP88 is expressed in human BC tumors in a positive correlation with their tumorigenicity. Increased GP88 expression is associated with resistance to anti-estrogen therapy in ER + cells and with herceptin resistance in Her-2 overexpressing breast tumors. Inhibition of GP88 expression in human breast adenocarcinoma inhibited tumor incidence and growth in nude mice. Immunohistochemical studies have shown that GP88 was expressed in invasive ductal carcinomas in correlation with the expression of poor prognosis markers whereas normal tissues and benign lesions were negative. High GP88 expression in tumor biopsies was accompanied by decreased disease-free survival. Since GP88 can be secreted, we have hypothesized that GP88 could be secreted in the circulation and found in serum. We examined whether GP88 could be found in the circulation and whether GP88 could be elevated in the sera of breast cancer patients when compared to healthy individuals.
 Methods: An IRB approved blood sampling study was conducted at the University of Maryland Breast Clinic to determine the serum level of GP88 in healthy volunteers (HV) and breast cancer patients (BC pts). Serum GP88 concentration was determined in triplicate by quantitative enzyme immunoassay. 189 BC pts were accrued. In addition, sera from 18 HV were obtained to establish a GP88 baseline in healthy volunteers. BC patient characteristics: Race: Caucasian- 91, African American-92, Asian-6; median age, 51 (range 29-86), stage I – 48, II - 52, III – 26, IV - 63.
 Results: Circulating GP88 was measurable in the serum. Median level of GP88 was 28.7 ng/ml (range 16.6-38.2) in HV; 40.7 ng/ml (range 6.4-100) in early stage (stage 1 –3) BC pts (p- value = 0.007) and 45.3 ng/ml (range 9.8 to 158.4) in stage 4 metastatic BC patients (p-value= 0.0007). Statistically significant increase in circulating GP88 level was found in early stages as well as in metastatic disease. Correlation studies with BC prognostic factors such as stage, tumor size, lymph node involvement, tumor grade and presence of ER and HER-2 will be presented.
 Conclusion: GP88 can be detected in the sera of HV and BC pts. Comparison between the two groups of subjects indicates that GP88 level is significantly higher in the sera of BC pts. These studies are important as they identify as a measurable circulating biomarker GP88 that is also a therapeutic target of malignant transformation or malignant progression of breast carcinoma (BC). Future studies will examine whether there is any correlation between the serum level of GP88 and therapeutic response to systemic therapy in breast cancer patients.
 This study was supported by grant from MIPS, the Avon Foundation and 1R43 CA 124179-01A1 from the National Institutes of Health.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2006.

Tissue expression of the growth factor GP88 is a predictor of recurrence in patients with estrogen receptor positive breast tumors

Abstract #1088

Background
 Our laboratory is working on the characterization of novel breast cancer targets that have therapeutic an/or diagnostic applications. We have previously identified the growth factor GP88 as a significant player of breast tumorigenesis. GP88 is expressed in human breast cancer cells in a positive correlation with tumorigenesis. In estrogen receptor positive breast cancer cells, GP88 mediates estrogen proliferation effect and its increase is associated with resistance to anti-estrogen therapy. Inhibition of GP88 expression in human breast adenocarcinoma lead to inhibition of tumor incidence and tumor growth in nude mice. Pathological studies showed that ductal carcinoma expressed GP88 whereas benign lesions and normal mammary tissue were negative. Based on this evidence, the present study was carried out to investigate whether high GP88 expression in estrogen receptor positive invasive ductal carcinoma is associated with increased recurrence and decreased overall survival.
 Methods
 Under an IRB approved study, 239 archival formalin-fixed, paraffin-embedded estrogen receptor positive invasive ductal carcinoma with a minimum of 4 years follow-up were obtained from three United States tumor banks The clinical data included patients demographics such as age and race, tumor characteristics including tumor size, tumor grade, nodal status, disease stage and receptor status, time and type of first recurrence, time and status of last follow-up. GP88 expression was determined by immunohistochemistry using Oncostain 88TM IHC kit on five-micrometer sections. GP88 expression was scored as: <10% of cells staining – negative, >10% of cells staining – positive with positive staining graded from weak/focal (1+) to moderate/focal or diffuse (2+) to strong/diffuse (3+). The statistical analysis of GP88 expression in all cases was carried out. The Oncostain 88TM test performance was evaluated for its ability to predict disease-free (DFS) and/or overall survivals (OS) using Kaplan Meier curves and the Cox proportional hazards models for quantification of risk.
 Results
 The data show that ER+ cases with high GP88 expression (3+) had a hazard ratio for OS of 2.29 (95% CI, 1.38-3.78; p< 0.0013) and a HR for DFS of 2.88 (95% CI 1.59-5.24; p<0.0005). GP88 3+ remained highly significant for OS and DFS even when the data were adjusted for covariates such as nodal status, disease stage, tumor grade, tumor size, supporting the findings that GP88 brings independent information on the recurrence risk and overall survival of ER+ invasive ductal carcinoma.
 Conclusion
 This study demonstrates for the first time that high GP88 expression (3+) is a predictor of higher recurrence and increased mortality in ER+ IDC. These data provide a novel biomarker tissue assay (Oncostain 88TM) with prognostic significance in breast cancer.
 This study was supported by grant 1R43 CA 124179-01A1 from the National Institutes of Health.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1088.

Genetic diversity of captive forest musk deer (Moschus berezovskii) inferred from the mitochondrial DNA control region

Forest musk deer (Moschus berezovskii) were once distributed widely in China. However, wild populations have declined dramatically because of poaching and habitat loss. Captive breeding populations have been established for several decades, but the genetic backgrounds of most captive populations were unclear and the population sizes increased very slowly. To provide useful information for conservation and management of this species, we investigated the genetic diversity and population structure of forest musk deer by analysing a 582-bp fragment of the mitochondrial DNA (mtDNA) control region (CR) in three captive breeding populations in Sichuan Province, China. Ninety-four variable sites and 27 haplotypes were observed in 109 individuals, and the nucleotide and haplotype diversities were relatively high compared with those of other endangered mammals. Of the three investigated populations, the Maerkang population had the highest nucleotide diversity (pi=0.0568), haplotype diversity (h=0.836) and average intra-population genetic distance (0.062). The analysis of molecular variance demonstrated that most variation occurred within samples and that there was significant differentiation of the three populations. Estimates of gene flow indicated that there were few genetic exchanges among the three populations. Building pedigree records and increasing gene flow between populations will be helpful for conserving these populations and this species.

Identifying quantitative trait loci for resistance to Sclerotinia head rot in two USDA sunflower germplasms

Sclerotinia head rot is a major disease of sunflower in the world, and quantitative trait loci (QTL) mapping could facilitate understanding of the genetic basis of head rot resistance and breeding in sunflower. One hundred twenty-three F2:3 and F2:4 families from a cross between HA 441 and RHA 439 were studied. The mapping population was evaluated for disease resistance in three field experiments in a randomized complete block design with two replicates. Disease incidence (DI) and disease severity (DS) were assessed. A genetic map with 180 target region amplification polymorphism, 32 simple sequence repeats, 11 insertion-deletion, and 2 morphological markers was constructed. Nine DI and seven DS QTL were identified with each QTL explaining 8.4 to 34.5% of phenotypic variance, suggesting the polygenic basis of the resistance to head rot. Five of these QTL were identified in more than one experiment, and each QTL explained more than 12.9% of phenotypic variance. These QTL could be useful in sunflower breeding. Although a positive correlation existed between the two disease indices, most of the respective QTL were located in different chromosomal regions, suggesting a different genetic basis for the two indices.

Treatment of osteonecrosis of the femoral head with hBMP-2-gene-modified tissue-engineered bone in goats

The efficacy of β-tricalcium phosphate (β-TCP) loaded with bone morphogenetic protein-2 (BMP-2)-gene-modified bone-marrow mesenchymal stem cells (BMSCs) was evaluated for the repair of experimentally-induced osteonecrosis of the femoral head in goats.

Bilateral early-stage osteonecrosis was induced in adult goats three weeks after ligation of the lateral and medial circumflex arteries and delivery of liquid nitrogen into the femoral head. After core decompression, porous β-TCP loaded with BMP-2 gene- or β-galactosidase (gal)-gene-transduced BMSCs was implanted into the left and right femoral heads, respectively. At 16 weeks after implantation, there was collapse of the femoral head in the untreated group but not in the BMP-2 or β-gal groups. The femoral heads in the BMP-2 group had a normal density and surface, while those in the β-gal group presented with a low density and an irregular surface. Histologically, new bone and fibrous tissue were formed in the macropores of the β-TCP. Sixteen weeks after implantation, lamellar bone had formed in the BMP-2 group, but there were some empty cavities and residual fibrous tissue in the β-gal group. The new bone volume in the BMP-2 group was significantly higher than that in the β-gal group. The maximum compressive strength and Young’s modulus of the repaired tissue in the BMP-2 group were similar to those of normal bone and significantly higher than those in the β-gal group.

Our findings indicate that porous β-TCP loaded with BMP-2-gene-transduced BMSCs are capable of repairing early-stage, experimentally-induced osteonecrosis of the femoral head and of restoring its mechanical function.

BMP2 gene therapy on the repair of bone defects of aged rats

Age-related decline in the number of mesenchymal stem cells (MSCs) and their reduced capability to differentiate osteogenically, along with diminished availability of growth factors, may be major factors accounting for reduced bone formation in the aging mammalian body. In the first part of the study, we compared the number of MSCs in bone marrow (BM) and the content of bone morphogenetic protein 2 (BMP2) in cortical bone tissue in juvenile, adult, and aged (1, 9, and 24 months, respectively) male rats. To assay the influence of aging on osteogenic differentiation ability, MSCs from the three age groups were transduced with the BMP2 gene. Following gene transduction, the production of BMP2 in culture media, expression of osteogenic proteins (e.g., alkaline phosphatase, type Ialpha1 collagen, osteopontin, and bone sialoprotein), as well as ectopic bone formation in athymic mice were compared. Results showed that the number of MSCs in BM as well as the content of BMP2 in cortical bone tissue decreased with age, but no significant differences between the three age groups were found with regard to production of BMP2 or capability of BMP2 gene-modified MSCs to differentiate osteogenically. The second part of the study applied BMP2 gene-modified autologous MSCs/beta-tricalcium phosphate for repair of bone defects in aged rats with positive results. Our data indicate that the osteogenic potential of MSCs of aged rats can be restored following BMP2 gene transduction and that this technique may be a useful approach in the future planning of gene therapy for age-related osteoporotic fractures.