Thoracic ultrasound for TB diagnosis in adults and children

Thoracic ultrasound is an appealing alternative to chest radiography for the diagnosis of TB. Based on research experience conducting thoracic ultrasound for adults and children in South Africa, three key considerations for potential scale-up were identified. First, thoracic ultrasound requires a comprehensive training programme for novice users; artificial intelligence may be used to simplify training and interpretation. Second, a robust ultrasound device is needed with good subpleural resolution and a probe suitable for children. Third, comprehensive scanning of the lungs is time-intensive, and shorter scanning protocols may be more feasible in clinical practice.

Abstract P5-08-05: The interplay between stromal density, epithelial mesenchymal transition and chemoresistance in breast cancer

Epithelial Mesenchymal Transition (EMT) refers to the transition of cells from a more differentiated epithelial phenotype to a less differentiated mesenchymal phenotype, a process that may be triggered by a range of therapeutic interventions including cytotoxic treatment, and which we have previously linked to poor breast cancer (BrCa) outcome after neoadjuvant chemotherapy (NAC)1. Mammographic breast density (MBD)represents the white radiographic appearance of epithelial and stromal breast tissue on a mammogram. High MBD in patients being treated for BrCa also associates with chemoresistance, correlating with lower pathological complete response rates (pCR)2. Linking these two stimuli, EMT can also be induced by artificial high-density stroma, where it also leads to chemoresistance in vitro3.

Here we set out to validate the link between poor outcome after NAC and EMT in a larger validatory patient cohort, and to ascertain the molecular drivers through which EMT is triggered in this setting. Further we look to confirm the association of high MBD with poor chemoresponse in the same cohort, and to assess whether this chemoresistance is mediated through EMT with the same drivers.

In a pilot cohort of 50 NAC-treated locally advanced BrCas with a pCR rate of 20%, pre-NAC biopsies and post-NAC surgical specimens were analysed for expression changes in a panel of EMT-related markers across treatment using 230 Nanostring assays. This included the EMT-driving transcription factors TWIST 1 and 2, SNAIL 1, 2 and 3 and ZEB 1 and 2, which were correlated with risk of relapse. Snail-3 showed significantly greater induction in relapsers compared to non-relapsers (OR=1.8, p=0.04) with a borderline significantly greater induction of TWIST-1 (OR=2.4, p=0.08) in relapsers in addition.

In a subsequent 240-patient validation cohort with a pCR rate of 18%, contralateral cranio-caudal view mammograms from the time of diagnosis have been collated and digitized with MBD assessment employing Cumulus software ongoing. Percent breast density will be assessed both as a continuous variable and by quartiles. Immunohistochemistry on pre- and post-operative tissue sections with pan-cytokeratin-vimentin co-staining to identify EMT and staining for SNAIL-3 and TWIST-1 is also in progress.

Associations between MBD, EMT before and after chemotherapy, pCR and relapse-free survival will be presented. The role of Snail-3 and TWIST-1 in the interplay between MBD, EMT and outcome is being explored and will be reported.

Citation Format: Agarwal V, Spalding LJ, Blick T, Dobrovic A, Thompson EW, Redfern A. The interplay between stromal density, epithelial mesenchymal transition and chemoresistance in breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-08-05.

Abstract P1-01-09: BMP4 suppresses the progression of breast cancer through altered expression of metastasis regulating genes

Metastasis is a lethal manifestation of cancer, the development of which is the major cause of death in cancer patients. During a search for metastasis-regulating elements, an inverse correlation was identified between the in vivo tumor expression of bone morphogenetic protein-4 (BMP4) and spontaneous metastasis in a panel of isogenic mammary tumors of varying metastatic capacity. BMP4 is an essential morphogen in development, regulating cellular mechanisms akin to those in metastasis, including cellular differentiation, pluripotency and apoptosis. We therefore initiated an investigation of the impact of BMP4 expression on the metastatic process.

We studied the effect of enforced expression of BMP4 in a highly metastatic mammary tumour model called 4T1.2, comparing in vitro properties and tumour progression in mice. There were no differences in proliferation in vitro or when implanted into the mammary gland of immunocompetent mice. In contrast, mice bearing equivalent-sized 4T1.2-BMP4 tumors revealed dramatically reduced metastasis to lung, lymph node and bone. In a parallel study where the established orthotopic primary tumor was resected, survival was significantly extended in mice bearing 4T1.2-BMP4 tumors. Enforced BMP4 expression in tumor cells introduced intravenously resulted in a 2.5-fold decrease in lung metastatic burden, consistent with the impaired capacity of tumor cells to survive in circulation and colonize the lung. Conversely, silencing BMP4 expression in separate weakly metastatic tumours enhanced their ability to colonize the lung and shortened the survival of the mice. No changes were found in the ability of tumor cells expressing BMP4 or treated with recombinant BMP4 to migrate or invade through Matrigel in chemotactic assays but BMP4 enhanced anoikis in both mouse and human breast cancer cells, indicating that BMP4 sensitizes disseminated cells to anoikic stresses induced by cell-substrate detachment and shear flow during systemic transit. BMP4 activated canonical BMP-SMAD signaling in our mammary tumours, leading to altered expression of known metastasis-regulating genes, including SMAD7. SMAD7 depletion in metastasis-deficient 4T1.2-BMP4 tumors accelerated the onset of metastatic disease.

In a meta-analysis of 3,587 breast cancer patients in publically available datasets, low BMP4 mRNA expression was significantly associated with reduced relapse-free survival (RFS) (HR = 0.85, P = 0.01). In an independent analysis using the BreastMark algorithm, low levels of BMP4 mRNA were associated with reduced RFS (HR = 0.88, P = 0.035), distant metastasis-free survival (HR = 0.83, P = 0.035) and overall survival (HR = 0.78, P = 0.006). At the protein level, in a tissue microarray from 415 treatment naïve patients, improved overall survival was observed in multivariate analysis for both BMP4 (HR = 0.66, P = 0.037) and SMAD7 expression (HR = 0.64, P = 0.035) individually. Expression of both proteins compared to neither further improved OS (HR = 0.55, P = 0.005).

In summary, we found strong evidence that BMP4 is a metastasis suppressor correlating inversely with metastatic potential in preclinical breast cancer models and predicting improved relapse-free and overall survival in breast cancer patients.

Citation Format: Redfern AD, Eckhardt BL, Cao Y, Sloan EK, Parker BS, Loi S, Ueno NT, Lau PK, Latham B, Anderson RL. BMP4 suppresses the progression of breast cancer through altered expression of metastasis regulating genes [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-01-09.

Abstract P2-06-01: Characterisation of C11orf67, an oncogenic driver in a new subtype of aggressive endocrine receptor positive breast cancer

The recent integration of both genomic and transcriptomic datasets have added a further dimension to the landscape of breast cancer (BrCa) subtyping, defining novel functional subgroups with distinctive oncogenic drivers that carry important implications for therapy. This integrative clustering has unveiled a novel subtype of hormone receptor positive (HR+) BrCa associated with high proliferation and very poor survival characterised by copy number amplification and overexpression of a cluster of candidate oncogenic drivers at the 11q13.5-14 locus (1). At the heart of this amplicon we have demonstrated the selective overexpression of C11orf67/AAMDC (Adipogenesis associated Mth938 domain containing) which encodes a hypothetical protein of 122 aa with unknown function. In a pilot tissue microarray of 75 BrCa cases C11orf67 amplification and expression were significantly correlated with hormone receptor positivity. These positive cases also demonstrated high risk features with 75% demonstrating lymph node involvement.

In functional elucidation studies knockdown of C11orf67 in the highly expressing T47D cell line lead to decreased cell proliferation, cell migration, anchorage independent cell growth and induction of senescence. T47D xenografts with stable shRNA-induced C11orf67 knockdowns introduced into BALB/c mice showed significantly lower tumour volumes relative to T47D with empty vector. A genome wide analysis of these T47D-C11orf67 shRNA cells compared to T47D-empty vector cells using the Illumina HumanHT-12 platform demonstrated 40 differentially expressed genes. Network analysis revealed a proliferation node, enriched in cell cycle proteins, and a metabolic node comprising several biosynthetic enzymes such as MTHFD1L involved in one-carbon folate metabolism. Supporting this link and pointing to potential utility in chemotherapy selection, induction of ectopic C11orf67 expression in MCF7 cells increased sensitivity to fluorouracil and methotrexate but not to paclitaxel.

Investigating potential novel binding partners and effectors, in yeast two hybrid screening C11orf67 was a found to associate strongly with RABGAP1L, a protein involved in controlling GTPase signalling, protein trafficking, and autophagy.

Exploring the molecular cues that control C11orf67 expression, our data suggest the locus is regulated by transcription factors associated with high proliferation and metabolic control, notably Myc and NFkB, as well as HRs. E2 lead to a significant down-regulation of C11orf67 in T47D cells, which was reversed by the antiestrogen drug tamoxifen, whereas PG significantly increased C11orf67 levels. In keeping with this MCF7 cells ectopically expressing C11orf67 were resistant to the anti-proliferative effects of tamoxifen compared to the parent cell line.

These observations endorse C11orf67 as a novel oncogenic driver with exciting therapeutic potential, which could serve to distinguish the HR+ tumours at high risk of relapse and guide both the selection of current chemotherapeutical and endocrine treatments as well as the design of future precision therapeutics, notably anti-folate/one carbon drugs and novel endocrine agents.

References

1. Curtis et al. Nature. 2012 Jun 21;486 (7403):346-52.

Citation Format: Redfern A, Rashwan R, Sorolla A, Ratajska M, Kardas I, Kuzniacka A, Parry J, Curtis C, Woo A, Sgro A, Biernat W. Characterisation of C11orf67, an oncogenic driver in a new subtype of aggressive endocrine receptor positive 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 P2-06-01.

Abstract P1-05-03: Predictive value of de novo and induced epithelial-mesenchymal transition in locally advanced breast cancer treated with neoadjuvant chemotherapy

The dynamic transformation of an adherent proliferative epithelial cell to a migratory and invasive mesenchymal state that can drive tumour metastasis has been widely acknowledged in in vitro models as epithelial-mesenchymal transition (EMT). We have characterized EMT status in tissues from 35 locally advanced breast cancer (LABC) patients before and after receiving anthracycline and taxane-based neoadjuvant chemotherapy (NAC). Routine analyses for ER, PR, HER2, lymphovascular invasion (LVI) and tumour staging parameters were available for all patients and five year recurrence and survival data was available for 34. Six patients (17%) had a pathological complete response (pCR), five of whom were hormone receptor (HR) negative and one HR positive. 11 patients (43%) had had disease recurrence and 10 (40%) had died from breast cancer at five years follow up.

Core biopsy tissue specimens were available prior to NAC from all 35 patients. Resected tissue following NAC was available from 17 cases with residual disease. Tissue sections were stained for the epithelial marker cytokeratin 19 (CK19) and the mesenchymal marker vimentin (VIM). Fluorescent, multi-channel microscopy identified co-localization of CK19 and VIM within tumour cells, indicating the presence of EMT.

Evidence of EMT prior to NAC was seen in 14/35 (40%) of LABC cases. There was no association between EMT status pre-NAC and pCR which was observed in 2/14 EMT positive and 4/21 EMT negative patients. However, in patients with detectable EMT pre-NAC there was significantly improved five year disease-free survival (86 vs. 52%, p=0.04) and a trend to improved five year overall survival (86 vs. 62%, p=0.12) compared to cases that were EMT negative pre-NAC.

Of the 17 cases without a pCR with tissue available for assessment of pre- and post-NAC EMT status, seven had disease recurrence and six died by five years. Four cases that were EMT negative pre-NAC developed EMT positive tumour cells following NAC, and all have subsequently developed metastatic disease and died from breast cancer. Two cases lost detectable EMT after chemotherapy, both of whom remain alive. In contrast to pre-NAC EMT, induction of EMT following NAC was associated with trends to worse five year disease-free and overall survival (45 v 75%, p=0.20) and (56 v 75%, p=0.40). Additionally, when events past five years are included in analysis, detectable EMT in the post-NAC tissue sample (induced and retained) correlated with a trend to increased recurrence (p=0.09) and to a statistically significant increase in overall mortality (p=0.04).

This is the first study to explore EMT induction and loss during NAC in the clinical setting. Although patient numbers are few, the data show EMT induction during chemotherapy in a moderate proportion of cases. Observations of significantly superior five year disease free survival in patients without detectable EMT pre-NAC and significantly inferior overall survival in those with visible EMT post-NAC need to be interpreted with caution. Larger studies are needed to further examine this potential prognostic differential between EMT detectable either before or after NAC, and to explore how this may guide therapy.

Citation Format: Redfern AD, McLaren SA, Dissanayake V, Chan A, Zeps N, Dobrovic A, Soon L, Thompson EW, Christobel SM. Predictive value of de novo and induced epithelial-mesenchymal transition in locally advanced breast cancer treated with neoadjuvant chemotherapy. [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 P1-05-03.

Abstract P1-09-08: Does adverse tumour biology contribute to inferior outcomes for Indigenous Australians diagnosed with breast cancer?

Background: Analyses across multiple Australian states have consistently demonstrated significantly inferior breast cancer survival for Indigenous patients (IPs). Studies compensating for increased remoteness, socioeconomic disadvantage and later presentation demonstrate a residual unexplained detriment. This survival disadvantage is confined to the first five years, akin to the inferior outcomes demonstrated by higher risk biological breast cancer subtypes. We postulated that a preponderance of such higher risk subtypes could explain the disparate mortalities.

Methods: The distribution of breast cancer subtypes in Western Australian IPs diagnosed between 2001 and 2010 was assessed to explore the contribution of adverse prognostic subtypes to poorer outcome. This was a retrospective cohort study of Indigenous women (n=114) and 3:1 age and remoteness matched non-Indigenous women (n=310) diagnosed with invasive, non-metastatic, unilateral breast cancer, who underwent definitive local treatment. Subtypes were assigned as luminal A, B, HER2 enriched and triple negative by ER, PR, HER2 and tumour grade comparisons. Differences in basic tumour demographics and biological sub-types were analysed and racial survival discrepancies explored within biological subtype cohorts.

Results: Hazards for overall and breast cancer-specific mortality in IPs were 4.07 (95% CI 2.55-6.49) and 4.19 (95% CI 2.42-7.25). IPs were significantly more likely to have grade 3 tumours (41 v 25%, p<0.001), LN positive disease (39 v 27%, p<0.001) and larger tumours (median 20 v 10 mm, p<0.001). No significant differences in proportions of classical histological sub-types (ductal v lobular) or in tumours showing ER, PR or HER2 positivity were observed. There were no significant differences in biological sub-type proportions although IPs were diagnosed with numerically more non-Luminal A subtypes (56 v 44%, p=0.08), accounted for by increased Luminal B (21 v 15%) and HER2 enriched (10 v 5%) sub-types. The significant relative five-year survival deficit for IPs noted overall (94 v73%, p<0.0001) was observed for each sub-type with the exception of HER2 positive patients. This extended from the relatively low risk luminal A sub-type where oral anti-estrogens are the mainstay of treatment (98 v 82%, p=0.0002) to the high risk triple negative sub-type where intravenous chemotherapy is the standard adjuvant therapy (94 v 50%, p=0.0014).

Conclusions: The contribution of adverse tumour biological subtype to poorer outcomes for Indigenous women is modest. Indigenous women with almost all biological subtypes fare significantly worse than their non-Indigenous contemporaries. Ongoing work includes more detailed biological comparisons of RNA expression and DNA mutation between groups as well as an exploration of potentially disparate treatment patterns.

Citation Format: Redfern A, Lee E, Bulsara M, Threlfall T, Harvey J, Cordell D. Does adverse tumour biology contribute to inferior outcomes for Indigenous Australians diagnosed with 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 P1-09-08.

Abstract P5-04-03: Bone morphogenic protein-4: A novel metastasis suppressor gene in breast cancer

Background: The combination of large-scale screening platforms and animal models of cancer, have provided much insight into the genetic mechanisms that control metastatic progression. Indeed, several studies have unraveled an essential role for genes that encode growth factors and extracellular matrix proteins in the progression of breast cancer. We have found that one such growth factor, bone morphogenic protein-4 (BMP4), to be significantly reduced in tumors with a high proclivity to metastasize. BMP4 is known to regulate tissue polarity and differentiation during embryogenesis, however it is not known whether BMP4 can functionally affect tumor progression.

Methods and results: In a panel of mammary tumor lines, we demonstrate an inverse correlation between metastatic propensity and the expression of BMP4 through a combination of RT-PCR, immunohistochemistry (IHC) and ELISA. These findings were extended to publicly available gene expression data sets, where low BMP4 expression was found to be associated with ER-negative breast tumors and in those tumors with high histologic grade. Low BMP4 expression also correlated with poorer survival from distant metastases (HR 0.82, p = 0.013). IHC analysis on a tissue microarray consisting of tumor specimens from 535 patients with invasive breast cancer demonstrated that, compared to normal breast epithelium, BMP4 positivity was significantly less common in both DCIS (HR 0.59, p = 0.00046) and invasive carcinoma (HR = 0.56, p<0.0000001), and was inversely associated with axillary lymph node-positivity (HR = 1.53, p = 0.055). Using surrogate in vitro assays of metastasis, we determined that BMP4 can suppress the ability of highly metastatic 4T1.2 tumor cells to resist anoikis. When BMP4 was overexpressed in 4T1.2 cells (4T1.2-BMP4) and orthotopically implanted in mice, we did not observe an effect on primary tumor growth, however elevated BMP4 expression did block the ability of these tumors to metastasize to the lymph node, lung and bone. In a reverse-complimentary approach, we confirmed that silencing of BMP4 expression by RNAi in weakly metastatic 4T07 and 168FARN cells, can enhance lung colonization. Mechanistically, we establish that BMP4 can induce canonical BMP-SMAD signaling in multiple breast cancer cells, leading to an up-regulation of genes known to suppress metastasis, and a down-regulation of metastasis promoting genes. Specifically, we link the anti-metastatic function of BMP4 to its ability to induce the expression of the known metastasis suppressor, Smad7. Through RNAi-mediated suppression of Smad7 in 4T1.2-BMP4 tumors, we were able to restore the metastatic phenotype of this tumor line. Finally, we demonstrate that administration of recombinant BMP4 protein in 4T1.2 tumor challenged mice elevates Smad7 expression within the primary tumor, and leads to a pronounced decrease in spontaneous bone and lung metastasis.

Conclusion: Utilizing animal models of cancer, and clinically sourced tissues, we provide correlative and functional data to prove that BMP4 is a bona fide metastasis suppressor gene in breast cancer. Furthermore, we demonstrate that BMP4 may be therapeutically viable, and can prevent breast tumor progression through the modulation of known ‘metastasis virulence’ genes.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-04-03.

Notch-induced transcription factors are predictive of survival and 5-fluorouracil response in colorectal cancer patients

Background:

The purpose of this study was to evaluate the expression of Notch-induced transcription factors (NTFs) HEY1, HES1 and SOX9 in colorectal cancer (CRC) patients to determine their clinicopathologic and prognostic significance.

Methods:

Levels of HEY1, HES1 and SOX9 protein were measured by immunohistochemistry in a nonmalignant and malignant tissue microarray of 441 CRC patients, and the findings correlated with pathologic, molecular and clinical variables.

Results:

The NTFs HEY1, HES1 and SOX9 were overexpressed in tumours relative to colonic mucosa (OR=3.44, P<0.0001; OR=7.40, P<0.0001; OR=4.08 P<0.0001, respectively). HEY1 overexpression was a negative prognostic factor for all CRC patients (HR=1.29, P=0.023) and strongly correlated with perineural and vascular invasion and lymph node (LN) metastasis. In 5-fluorouracil (5-FU)-treated patients, the tumour overexpression of SOX9 correlated with markedly poorer survival (HR=8.72, P=0.034), but had no predictive effect in untreated patients (HR=0.70, P=0.29). When HEY1, HES1 and SOX9 expression were combined to predict survival with chemotherapy, in treated patients there was an additive increase in the risk of death with each NTF overexpressed (HR=2.09, P=0.01), but no prognostic import in the untreated patient group (HR=0.74, P=0.19).

Conclusion:

The present study is the first to discover that HEY1 overexpression correlates with poorer outcome in CRC, and NTF expression is predictive of CRC patient survival with 5-FU chemotherapy. If confirmed in future studies, testing of NTF expression has the potential to enter routine pathological practice for the selection of patients to undergo chemotherapy alone or in combination with Notch inhibitors.

P5-22-01: Feasibility and Patient Safety of Serial Biopsies (bx) in Metastatic HER2−Positive Breast Cancer (BC) To Evaluate Alterations in Molecular Biomarkers (BM): Preliminary Results of SHERsig (Study of HER2 Signature in Metastatic Breast Cancer) a Prospective Phase II Study

Background

The use of trastuzumab (H)-based therapy for HER2−positive BC has significantly altered outcomes. Yet up to 64% of metastatic patients (pts) fail to respond (Robert JCO 2006) and most pts will progress within 24–42 months (m) following an initial response for metastatic disease. Preclinical data suggest several in vitro resistance mechanisms but confirmatory in vivo data are lacking, preventing optimal personalized care. This ongoing proof-of-concept study examines serial bx in pts with HER2−positive metastatic BC in order to assess BM profiles across multiple lines of treatment.

Methods: Key eligibility criteria include: centrally confirmed HER2 status, minimum of 1 disease site considered suitable for serial bx, normal coagulation profile and cardiac function, prior adjuvant/neoadjuvant taxane and H completed ≥12 m and ≥6 m respectively, ECOG ≤2. Pts receive q3wk H with clinician choice of taxane (docetaxel 75–100 mg/m2 q21, paclitaxel 80 mg/m2 weekly or 175 mg/m2 q21 [TH]). At the time of progressive disease, pts receive capecitabine (X) and H. Two core bx and 1 optional fine needle aspirate are performed at the following times: baseline (after 3 weeks [w] of TH), at 6 w, at time of first progression prior to XH, and at the time of progression on XH. Tumor assessments are performed at 6 w, then 9 w intervals, with cardiac assessment every 6 m. Primary endpoint aims to explore and potentially define BM signatures that could alter during HER2−targeted therapy and predict for decreased or increased sensitivity to H-based treatment. Secondary endpoints include bx safety, ORR and TTP. At time of baseline bx, pts have the option to complete a pt satisfaction questionnaire.

Results: Between August 2009 and June 2011, 58 pts were screened; 29 enrolled. The other 29 pts were screen failures, with 3 pts (5%) specifically declining entry due to the requirement for serial bx. Median age is 53 y (range 37–86), with 9 and 20 pts having recurrent or de novo metastatic disease. Eight pts received adjuvant systemic treatment, including H in 4 pts. Baseline bx performed in the breast, n (%): 15 (52), bone: 6 (21), liver: 4 (14), and lymph nodes: 4 (14); 14 and 27 pts underwent bx at 3 and 6 w respectively. After a median of 34 w of treatment 11 pts progressed on TH and 7 pts underwent planned bx. There were 12 SAEs, none related to bx. Most AEs were grade 1/2 (95%) with 3% grade 3 and 1 death due to intercurrent illness. From a total of 43 bx, 12 (27%) grade 1/2 AEs (hematoma 2, transient hypotension 2, mild pain 8) were reported, with resolution in all instances. Fifteen pts consented to the pt satisfaction substudy.

Conclusions: Preliminary results of the first reported serial bx study in metastatic BC demonstrated 95% pt acceptance of this approach. Evaluation of BM profiles will be conducted following planned recruitment of 50 pts. To date, the feasibility and safety of obtaining serial bx in metastatic BC is supported by the current safety profile and patient uptake. Updated recruitment data will be presented.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-22-01.

Peroxisome proliferator activated receptor-gamma (PPAR-gamma) mediates the action of gamma linolenic acid in breast cancer cells

Gamma linolenic acid (GLA) is a polyunsaturated fatty acid, which induces cytotoxicity and regulates cell adhesion in cancer cells. The molecular mechanism of these actions is not clear. We have shown that GLA acts via peroxisome proliferator activated receptors (PPARs), by stimulating their phosphorylation and translocation to the nucleus. Removing PPAR gamma with antisense oligos abolished the effect of GLA on the expression of adhesion molecules and tumour suppressor genes, whereas removal of PPAR alpha had no effect. Tissues from patients with breast cancer showed a reduction of expression of both PPARs in cancer tissues, as compared with normal. Thus, PPAR gamma serves as the receptor for GLA in the regulation of gene expression in breast cancer cells.