Thymidine phosphorylase expression and benefit from capecitabine in patients with advanced breast cancer.

BACKGROUND AND AIM: Capecitabine is an orally bioavailable prodrug that is converted to 5-fluorouracil through several enzymatic steps, the last of which is mediated by thymidine phosphorylase (TP). TP has been reported to be expressed at higher levels in cancer tissue compared with normal counterpart. The present study aimed at evaluating the potential relationship between TP expression and benefit from capecitabine in patients with metastatic breast cancer (BC). METHODS: Immunohistochemistry for TP and other biological markers was carried out on paraffin-embedded cancer tissues of 61 patients with BC treated with at least three cycles of capecitabine as single agent for metastatic disease. All patients had received capecitabine 1000 mg/m(2) b.i.d. days 1-14 every 21 days. The following variables were analyzed as potential determinants of benefit from capecitabine: TP expression, estrogen receptor (ER) and progesterone receptor status, human epidermal growth factor receptor-2 (HER-2) status, MIB-1 expression, performance status at the beginning of capecitabine treatment, stage at diagnosis, grade, presence of visceral metastases at the beginning of capecitabine treatment, and previous chemotherapy. RESULTS: Overall, median time to progression (TTP) was 6.5 months (range 1.4-33). On multivariate analysis, ER status [hazard ratio (HR) for progression = 0.31; 95% confidence interval (CI) = 0.15-0.64; P = 0.002], presence of visceral metastases at the beginning of capecitabine treatment (HR = 2.30; 95% CI = 1.21-4.39; P = 0.01), and capecitabine as first- or second-line treatment (HR = 2.28; 95% CI = 1.21-4.32; P = 0.01) independently predicted TTP. TP was highly expressed in 34 of 61 cases (55.7%). In the subgroup of patients with TP-expressing tumor, TTP was significantly longer in patients who received anthracyclines and taxanes before capecitabine (median TTP 7.5 versus 3.3 months, P = 0.01, log-rank test). Similarly, patients with a TP-positive tumor showed a longer TTP if they received taxanes before capecitabine than patients with TP-positive tumor who did not receive this treatment (7.3 versus 3.4 months, P = 0.03). CONCLUSIONS: These data provide further evidence that TP expression in BC could represent a biomarker of sensitivity to capecitabine treatment. Prospective studies with translational approach are desirable to confirm the predictive and prognostic role of TP.

Expression of periostin in human breast cancer.

BACKGROUND: Periostin is a secreted adhesion protein, normally expressed in mesenchime-derived cells. Aberrant expression of the periostin gene in epithelial tumours seems to play a role in angiogenesis and metastases. AIMS: To investigate periostin expression in a consecutive series of breast carcinomas and correlate it with established biological and prognostic factors. METHODS: A consecutive series of 206 breast carcinomas was investigated by immunohistochemistry with a specific antiperiostin antibody. Immunohistochemical expression of oestrogen and progesterone receptors, Ki-67 (MIB-1), HER-2/neu, VEGF-A, VEGFR-1 and VEGFR-2 was analysed. Periostin expression was also investigated in MCF-7 and MDA-468 cell lines by immunohistochemistry, western blot and quantitative RT-PCR. Localisation of periostin was investigated in MCF-7 cells by the green fluorescent protein (GFP) approach. RESULTS: Periostin was highly expressed in carcinoma cells, but not in normal breast tissues. The pattern of expression was mainly cytoplasmic. However, in 12% of cases a nuclear reactivity was observed. Nuclear periostin significantly correlated with tumour size, and with expression of oestrogen receptor, progesterone receptor, VEGF-A, VEGFR-1 and VEGFR-2. A nuclear localisation of periostin was also observed in MCF-7 and MDA-468 cell lines. In MCF-7 cells the nuclear localisation of periostin was also shown by transfection of a vector expressing a GFP-periostin chimeric protein. CONCLUSIONS: Results indicate that the aberrant gene expression of periostin in breast cancer cells is associated with an abnormal nuclear localisation of the protein. The nuclear localisation of periostin in breast cancer may induce significant biological effects.