Heterogeneous addiction to transforming growth factor-beta signalling in recessive dystrophic epidermolysis bullosa-associated cutaneous squamous cell carcinoma.

BACKGROUND: Recessive dystrophic epidermolysis bullosa (RDEB) is associated with a high mortality rate due to the development of life-threatening, metastatic cutaneous squamous cell carcinoma (cSCC). Elevated transforming growth factor-beta (TGF-ß) signalling is implicated in cSCC development and progression in patients with RDEB. OBJECTIVES: To determine the effect of exogenous and endogenous TGF-ß signalling in RDEB cSCC with a view to assessing the potential of targeting TGF-ß signalling for RDEB cSCC therapy. METHODS: A panel of 11 patient-derived RDEB cSCC primary tumour keratinocyte cell lines (SCCRDEBs) were tested for their signalling and proliferation responses to exogenous TGF-ß. Their responses to TGF-ß receptor type-1 (TGFBR1) kinase inhibitors [SB-431542 and AZ12601011 (AZA01)] were tested using in vitro proliferation, clonogenicity, migration and three-dimensional invasion assays, and in vivo tumour xenograft assays. RESULTS: All SCCRDEBs responded to exogenous TGF-ß by activation of canonical SMAD signalling and proliferative arrest. Blocking endogenous signalling by treatment with SB-431542 and AZ12601011 significantly inhibited proliferation (seven of 11), clonogenicity (six of 11), migration (eight of 11) and invasion (six of 11) of SCCRDEBs. However, these TGFBR1 kinase inhibitors also promoted proliferation and clonogenicity in two of 11 SCCRDEB cell lines. Pretreatment of in vitro TGFBR1-addicted SCCRDEB70 cells with SB-431542 enhanced overall survival and reduced tumour volume in subcutaneous xenografts but had no effect on nonaddicted SCCRDEB2 cells in these assays. CONCLUSIONS: Targeting TGFBR1 kinase activity may have therapeutic benefit in the majority of RDEB cSCCs. However, the potential tumour suppressive role of TGF-ß signalling in a subset of RDEB cSCCs necessitates biomarker identification to enable patient stratification before clinical intervention.

Multiparameter DNA content analysis identifies distinct groups in primary breast cancer.

BACKGROUND: Multiparameter flow cytometry is a robust and reliable method for determining tumour DNA content applicable to formalin-fixed paraffin-embedded (FFPE) tissue. This study examined the clinical and pathological associations of DNA content in primary breast cancer using an improved multiparametric technique. METHODS: The FFPE tissue from 201 primary breast cancers was examined and the cancers categorised according to their DNA content using multiparametric flow cytometry incorporating differential labelling of stromal and tumour cell populations. Mathematical modelling software (ModFit 3.2.1) was used to calculate the DNA index (DI) and percentage S-phase fraction (SPF%) for each tumour. Independent associations with clinical and pathological parameters were sought using backward stepwise Binary Logistic Regression (BLR) and Cox's Regression (CR) analysis. RESULTS: Tumours were grouped into four categories based on the DI of the tumour cell population. Low DI tumours (DI=0.76-1.14) associated with progesterone receptor-positive status (P=0.012, BLR), intermediate DI (DI=1.18-1.79) associated with p53 mutant tumours (P=0.001, BLR), high DI (DI1.80) tumours with human epidermal growth factor receptor 2 (HER2)-positive status (P=0.004, BLR) and 'multiploid tumours' (two or more tumour DNA peaks) did not show any significant associations. Tumours with high SPF% (10%) independently associated with poor overall survival (P=0.027, CR). CONCLUSION: Multiparametric flow analysis of FFPE tissue can accurately assess tumour DNA content. Tumour sub-populations associated with biomarkers of prognosis or likely response to therapy. The alterations in DNA content present the potential for greater understanding of the mechanisms underlying clinically significant biomarker changes in primary breast cancer.