Abstract P5-01-09: Identification of Molecular Apocrine Triple Negative Breast Cancer Using a Novel 2-Gene Assay and Comparison with Androgen Receptor Protein Expression and Gene Expression Profiling by DASL

Background: The molecular apocrine (MA) subtype of breast cancer is identified by gene expression profiling. MA tumors are estrogen receptor (ER) negative and progesterone receptor (PR) negative, but still express estrogen responsive genes. The androgen receptor (AR) pathway may be driving growth in these tumors because androgen responsive genes are expressed in tumors with the MA gene signature. The MA gene signature is identified in approximately 10% of triple negative breast cancer (TNBC) and may predict patients with tumors responsive to agents that inhibit the AR pathway. AR protein expression, measured by immunohistochemistry (IHC), may be a surrogate for the MA gene signature, but to date, a careful comparison of gene expression profiles and AR protein expression has not been conducted. In this study, cohorts of TNBCs were assessed for the MA gene signature and these results were compared with AR IHC expression and with a novel gene expression assay that may predict tumors with the MA gene signature.

Methods: Formalin fixed, paraffin-embedded (FFPE) TNBC samples were commercially obtained. ER, PR and HER2 status of these samples was confirmed by IHC. AR expression was detected by IHC using two different antibody clones. Both staining intensity and percent positive cells were recorded for each sample. Gene expression data was collected from a cohort of TNBC FFPE samples using cDNA-mediated Annealing, Selection, extension, and Ligation (DASL) technology. A 2-gene classifier of the MA gene expression signature was derived by interrogating publically available gene expression data from ER-negative breast cancers. A reverse-transcriptase polymerase chain reaction (RT-PCR) assay to detect the 2-gene classifier was developed. Cell lines predicted to have the MA gene signature by the 2-gene assay were tested for sensitivity to R-1881 in vitro.

Results: Using computational approaches and publically available datasets, we confirmed the validity of the MA gene signature and estimated the prevalence to be between 12% and 37% in ER-negative breast tumors. The 2-gene classifier was 100% specific in determining MA tumors in a training set using gene expression data as a standard. In a validation set, the 2-gene assay was 66% correlative with AR IHC positivity when the IHC cut-off was set at 10% positive tumor cells. Cell lines predicted to express the MA gene signature by the 2-gene classifier proliferated in response to androgen. This effect was blocked by Flutamide.

Conclusions: These results indicate that AR IHC using a 10% cut-off may not completely correlate with the MA gene signature. Further refinement of AR IHC scoring criteria may produce greater specificity. Cell proliferation data suggests the 2-gene assay can predict tumors that will proliferate in response to androgen. Work is ongoing to determine the correlation between the 2-gene assay results, AR IHC and DASL gene expression data to fully understand the predictability of this assay. Understanding this correlation may allow use of simple clinical assays to accurately select patients responsive to agents that block AR signaling.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-01-09.

The role of plastidial glucose-6-phosphate/phosphate translocators in vegetative tissues of Arabidopsis thaliana mutants impaired in starch biosynthesis

Arabidopsis thaliana mutants impaired in starch biosynthesis due to defects in either ADP glucose pyrophosphorylase (adg1-1), plastidic phosphoglucose mutase (pgm) or a new allele of plastidic phosphoglucose isomerase (pgi1-2) exhibit substantial activity of glucose-6-phosphate (Glc6P) transport in leaves that is mediated by a Glc6P/phosphate translocator (GPT) of the inner plastid envelope membrane. In contrast to the wild type, GPT2, one of two functional GPT genes of A. thaliana, is strongly induced in these mutants during the light period. The proposed function of the GPT in plastids of non-green tissues is the provision of Glc6P for starch biosynthesis and/or the oxidative pentose phosphate pathway. The function of GPT in photosynthetic tissues, however, remains obscure. The adg1-1 and pgi1-2 mutants were crossed with the gpt2-1 mutant defective in GPT2. Whereas adg1-1/gpt2-1 was starch-free, residual starch could be detected in pgi1-2/gpt2-1 and was confined to stomatal guard cells, bundle sheath cells and root tips, which parallels the reported spatial expression profile of AtGPT1. Glucose content in the cytosolic heteroglycan increased substantially in adg1-1 but decreased in pgi1-2, suggesting that the plastidic Glc6P pool contributes to its biosynthesis. The abundance of GPT2 mRNA correlates with increased levels of soluble sugars, in particular of glucose in leaves, suggesting induction by the sugar-sensing pathway. The possible function of GPT2 in starch-free mutants is discussed in the background of carbon requirement in leaves during the light-dark cycle.

Brahman bull fertility in a north Australian rangeland herd

Low and variable bull fertility was identified as a constraint on reproductive rates in beef cattle grazed in an extensive, multiple sire mating regimen on Mount Bundey station in the Darwin pastoral district of northwestern Australia. Erratic conception patterns were attributed to a high proportion of bulls with low breeding soundness evaluation scores (BSE), a high proportion of aged bulls (40%>8 yr), and to running bulls of mixed age groups. Liveweight, scrotal circumference (SC) and age were positively correlated. An experiment was subsequently designed to investigate the ability of a number of bull measurements to predict fertility in an extensively-managed, multiple-sire mating system. Blood typing was used to match calves to sires. It proved to be an accurate and useful technique which successfully identified the parentage of 94% of calves examined. Single measurements of serum testosterone after administration of gonadotrophin-releasing hormone (GnRH) were not correlated with fertility. However six of the seven most fertile bulls exhibited high peak serum testosterone levels in summer, and lower levels in the winter. In contrast, the less fertile bulls did not exhibit seasonal variation in GnRH-induced serum testosterone levels. Social dominance ratio was weakly related to fertility (r=0.51: P<0.05). BSE (r=0.51: P<0.05) and SC (r=0.49: P<0.05) prior to, but not subsequent to, mating were correlated with bull fertility. Under the conditions of this experiment, a bull to cow ratio of 1:20 was excessive for bulls with a satisfactory BSE score.

Hip fracture implants increase serum metal levels

OBJECTIVE

Hip fractures are disabling accidents in the elderly. The purpose of this prospective study was to investigate systemic exposure to metals from hip implants used for fracture fixation.

MATERIAL AND METHODS

Serum levels of Cr, Ni and Mo in patients with compression hip screws (n = 22) or cervical fracture screws (n = 23) were measured by inductively coupled plasma mass spectrometry. Blood samples were collected before surgery and at 3 and 12 months postoperatively.

RESULTS

At 3 months, patients with compression hip screws showed higher concentrations of Cr and Ni than did those with cervical screws. Both types of screws led to a 2-fold increase in serum Mo, which was not expected for the freestanding cervical screws. After 12 months, the levels had decreased, but the compression hip screw was still associated with higher values for Cr and Mo.

CONCLUSIONS

The difference between the screws is most likely due to the potential for fretting and crevice corrosion between components in the compression hip screws. The apparent short-term systemic elevation of stainless steel elements in patients with hip screws does not support routine removal of asymptomatic hip fracture implants.

Nickel contamination from an intravenous catheter used for infusion

At the outset of a clinical research project involving metal analyses on patients receiving metal devices in conjunction with hip fractures, unexpected high concentrations of nickel were discovered in serum samples taken before surgery. The median nickel concentration in 30 patients was 4.6 microg/l (highest 19.5 microg/l), while reference values in non-exposed persons are reported to be 0.05-1.2 microg/l. The sampling and analyzing procedures were scrutinized without positive identification of the source of contamination. A review of all relevant procedures was then undertaken. It was identified that the nickel contamination originated from the intravenous catheter which was always put in place immediately after the patient's admission to the hospital, and thus before the blood sampling. Close inspection of the intravenous catheter revealed that it contained a nickel-plated brass funnel inside the hub of the device which released nickel into the Ringer-acetate passing through the catheter. The present catheter has been the standard device used at Haukeland University Hospital for the past 6 years. Patients have consequently been exposed to small amounts of nickel. The clinical relevance of the exposure cannot be determined. For the patients included in the research project, a metal-free alternative was used. These findings show that the quality and properties of everyday medical devices should be scrutinized, at least before being used for special purposes.

Expansion of the canine A blood group system

A detailed study of the canine A blood group system was undertaken, resulting in the expansion of this system into a three-factor, four-allelic one with the recognition of an additional subtype, a3. The serological and extensive family data supported the proposed genetic theory of four alleles with dominance with the order being Aa1, Aa2, Aa3 and A-. Gene frequencies of the alleles were determined in various breeds of dogs with frequencies in the general Brisbane population being 0.244 (Aa1), 0.042 (Aa2), 0.045 (Aa3) and 0.669 (A-).

A new transferrin allele in Australian goats

Subdivision of TF B into two variants, B1 (faster) and B2 (slower) in Australian goat breeds was accomplished by high voltage, thin layer polyacrylamide gel electrophoresis at pH 7.9. The genes controlling the caprine transferrins were shown to be autosomal codominant alleles, TFA, TFB1, TFB2 and TFC and in the various breeds of goats, the alleles were in Hardy-Weinberg equilibrium. TFA was the most common allele in the Australian and Texan Angora, Cashmere and Dairy breeds with gene frequencies ranging from 0.652 to 0.977. TFB1 and TFB2 occurred in all four breeds while TFC was only observed in very low frequencies in Australian Angora and Cashmere breeds.

Genetic polymorphism of plasma vitamin D-binding protein (GC) in Australian goats

Polymorphism at the GC locus in goats was detected using isoelectric focusing (pH 4.5-5.4) and immunoblotting with antiserum to human GC. Three variants, designated A, B and C in order of decreasing mobility to the anode, were detected and were shown to be controlled by three codominant alleles, GCA, GCB and GCC. GCA and GCB occurred in all four breeds (Australian and Texan Angora, Cashmere and Dairy) with GCA being the most common and having gene frequencies ranging from 0.851 to 0.993. GCC was found only in Australian Angora and Cashmere animals. The products of the three GC alleles had isoelectric points in the range pH 4.63-4.95 and M(r) of approximately 54,375. The major isoforms of the three alleles were shown to contain sialic acid. Linkage between the GC and albumin loci was unable to be demonstrated due to the low frequency of ALBA (0.02) in the Cashmere breed.

Relationships between the bovine major histocompatibility system and commonly recognized erythrocyte and serum polymorphisms

Linkage at a recombination frequency of 0.10 or less between the bovine major histocompatibility system and the B, C and L red blood cell groups and the albumin, haemoglobin and transferrin loci was excluded by Morton's lod score method. The white blood cell antigen CA19, which is independent of the bovine major histocompatibility system, is the J blood group.

Canine blood groups: description of 20 specificities

Twenty blood typing reagents, four agglutinins and 16 operable in the antiglobulin test, were prepared from 54 antisera which were produced in 24 dogs. Two of the reagents were identified as anti-B and Nf6. Two of the antigens were shown by absorption and family studies to be linear subtypes. In most cases, detailed family studies demonstrated a Mendelian dominant inheritance for the genes controlling the canine red cell antigens. Gene frequencies were determined in various breeds of dogs and in the dingo.

Frequencies of plasma protease inhibitor alleles in Australian horse breeds and the recognition of two new alleles

Investigation of the plasma protease inhibitor system (Pi) in the Arabian and quarter horse breeds and re-examination of the standardbred breed resulted in the recognition of two new Pi alleles, designated E and L2. PiE is rare and has been found in only three quarter horses. In contrast, PiL2 is relatively common in the standardbred (0.107) and allowed subdivision of PiL into PiL and PiL2. Splitting of PiL resulted in an exclusion probability (PE) of 0.649 for the standardbred Pi system. Frequencies of the Pi genes have now been determined for four breeds (thoroughbred, standardbred, quarter horse and Arabian) of horses in Australia.

Characterisation of the alpha 1-protease inhibitor system in Thoroughbred horse plasma by horizontal two-dimensional (ISO-DALT) electrophoresis. 1. Protein staining

The isoelectric points and the molecular weights of the major components of the eight Thoroughbred protease inhibitor (Pi) types have been determined by polyacrylamide gel isoelectric focusing and polyacrylamide gel pore gradient (ISO-DALT) electrophoresis respectively. The major Pi proteins focus in the range pH 3.74-4.43 and have molecular weights ranging from 55 000-72 000 daltons. Using the ISO-DALT method of electrophoresis, protein maps for the eight Thoroughbred Pi types have been presented for the first time. None of the homozygous Pi types are identical except for the types S1 and S2 which show partial identity. The results do not necessarily support Juneja et al.'s (1979) contention of two closely linked alpha 1 Pi systems based on molecular weight differences. It is suggested that the traditional nomenclature originally proposed by Braend (1970) be maintained to describe the eight Pi alleles in Thoroughbred horse plasma. The ISO-DALT method provides a sensitive technique which is superior to existing techniques for the analysis of the horse Pi system.

Protease inhibitor system in horses: classification and detection of a new allele

A method of horizontal thin layer polyacrylamide gel electrophoresis at acid pH has been developed for the separation of the prealbumins in equine plasma. Using this method, it has been possible to split the S allele into two, S1 and S2, bringing the total number of prealbumin alleles in Thoroughbred horses to eight. The gene frequencies of these eight alleles in Australian Thoroughbreds are presented. All eight prealbumin types exhibit antiprotease activity and therefore, it is suggested that the name prealbumin (Pr) should be abandoned in favour of protease inhibitor (Pi) although at this stage it is not known whether this incorporates the Pi1 and Pi2 described by Junega et al. (1979).

ISO-DALT characterization of 12 'new' equine plasma protease inhibitor (Pi) alleles

Twelve equine protease inhibitory alleles, PiE, H, J, K, L2, O, P, Q, R, V, X, Z, have been characterized in terms of isoelectric point, molecular mass and inhibitory activity to bovine trypsin and chymotrypsin by ISO-DALT electrophoresis. Protein maps for 20 Pi alleles including those of the eight 'Thoroughbred' alleles (PiF, G, I, L, N, S1, S2, U) have now been determined. Five pairs of alleles, S1/S2, G/K, L/L2, P/R and U/Z, possessed varying numbers of common proteins ranging from one protein in the case of G/K and L/L2 to six in the case of U/Z. Based on these results and studies of the abnormal expressions of PiF, PiL and PiS1, a theory of at least three closely linked loci has been postulated to account for the marked heterogeneity of the equine protease inhibitory system.

The plasma protease inhibitor system (Pi) of Standardbred horses

The plasma protease inhibitor system (Pi) of Standardbred horses was studied by thin-layer, high-voltage, acid polyacrylamide gel electrophoresis (pH 4.6) followed by protein staining and staining for trypsin and chymotrypsin inhibition. In addition to the eight Thoroughbred alleles (PiF, G, I, L, N, S1, S2, U), another 10 alleles, designated PiH, J, K, O, P, Q, R, V, X, Z, were postulated to account for the 98 Pi types which were observed in Standardbreds. Detailed inhibitory spectra of the 'new' alleles were determined and further exceptions to the Pi1, Pi2 classification of Juneja et al. (1979) were found. Limited family data demonstrated the genetic nature of the 'new' variants and confirmed the allelic inheritance of the 'new' Pi variants.