The next generation of PI3K-Akt-mTOR pathway inhibitors in breast cancer cohorts

The PI3K/Akt/mTOR pathway plays a role in various oncogenic processes in breast cancer and key pathway aberrations have been identified which drive the different molecular subtypes. Early drugs developed targeting this pathway produced some clinical success but were hampered by pharmacokinetics, tolerability and efficacy problems. This created a need for new PI3K pathway-inhibiting drugs, which would produce more robust results allowing incorporation into treatment regimens for breast cancer patients. In this review, the most promising candidates from the new generation of PI3K-pathway inhibitors is explored, presenting evidence from preclinical and early clinical research, as well as ongoing trials utilising these drugs in breast cancer cohorts. The problems hindering the development of drugs targeting the PI3K pathway are examined, which have created problems for their use as monotherapies. PI3K pathway inhibitor combinations therefore remains a dynamic research area, and their role in combination with immunotherapies and epigenetic therapies is also inspected.

Role of the insulin-like growth factor 1 axis and visceral adiposity in oesophageal adenocarcinoma

BACKGROUND

Epidemiological studies have linked obesity with many cancers. The insulin-like growth factor (IGF) 1 axis may be an important mediator in obesity-associated cancer. This study examined the relationship between IGF-1 and its receptor (IGF-1R) in oesophageal adenocarcinoma, a cancer strongly linked to obesity.

METHODS

Patients with oesophageal adenocarcinoma considered suitable for attempted curative treatment were studied. Visceral adiposity was defined by waist circumference or visceral fat area. Free and total IGF-1 in serum were measured by enzyme-linked immunosorbent assay. Quantitative polymerase chain resection was used to determine mRNA expression of IGF-1 and IGF-1R in resected tumour samples. IGF-1R expression in tissue microarrays (TMAs) was quantified by immunohistochemistry.

RESULTS

A total of 220 patients were studied. Total and free IGF-1 levels were significantly increased in the serum of viscerally obese patients. Gene expression analysis revealed a significant association between obesity status and both IGF-1R (P = 0·021) and IGF-1 (P = 0·031) in tumours. TMA analysis demonstrated that IGF-1R expression in resected tumours was significantly higher in viscerally obese patients than in those of normal weight (P = 0·023). Disease-specific survival was longer in patients with negative IGF-1R expression than in those with IGF-1R-positive tumours (median 60·0 versus 23·4 months; P = 0·027).

CONCLUSION

This study highlighted the association of the IGF axis with visceral obesity, and a potential impact on the biology of oesophageal adenocarcinoma through its receptor. Targeting the IGF axis may have a rationale in future studies.

Abstract 1556: Adipose tissue upregulates MMP9 expression in oesophageal cancer promoting invasion and migration in vitro and correlates with obesity status and poor differentiation in vivo

Introduction: Obesity is an independent risk-factor for oesophageal adenocarcinoma. Adipose tissue is an endocrine organ secreting numerous factors with different biological activities. We aimed to investigate the molecular mechanisms linking obesity and cancer in oesophageal cancer.

Methods: Adipose conditioned media (ACM) was prepared from omental adipose tissue of oesophageal adenocarcinoma patients. Proliferation of oesophageal adenocarcinoma cells(OE33, OE19) in response to ACM was examined by BrdU. OE33 cell line was co-culture with visceral adipose tissue and gene expression pathways assessed by Cancer-Pathway-Finder and Affymetrix arrays. Identified genes were assessed in 50 resected oesophageal tumours and related to clinic-pathological data. Migration and invasion following culture with ACM was assessed in oesophageal cell lines.

Results: Culture of both the OE33 and OE19 cell lines with ACM from omental adipose tissue increased proliferation by 142% and 145% respectively. Co-culture of OE33 with adipose tissue increased the expression of genes regulating invasion and metastasis between 10-5000 fold, with MMP9 the most upregulated gene and TP53 down-regulated 2-fold. Altered genes were validated in an independent cohort. Functionally, co-culture of adipose tissue with tumour cells increased both mingration and invasion of tumour cells. Notably, adipose tissue from viscerally obese patients had a significantly higher effect. Markers of focal adhesions(SPP1, integrins), endothelial mesenchymal transition(SNAI2, Laminins) and thrombosis (pai-1) were also significantly upregulated. Expression of pai-1 and MMP9 was significantly (p<0.05) higher in tumours from centrally obese patients.

Conclusion: Omental adipose tissue promoted oesophageal cancer aggressiveness by increasing proliferative, migratory and invasive capacity via upregulation of MMP2, MMP9, SERPINE1, PAI-1, SPP1 and SNAI2. Upregulation of genes in tumours from obese patients suggest a molecular progression of cancer associated with excess adipose tissue.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1556. doi:10.1158/1538-7445.AM2011-1556