Asbestos Cancer Update 2008

Department of Biology, University of Rome Tor Vergata, Rome, Italy.

The elimination of tumor cells by apoptosis is the main mechanism of action of chemotherapeutic drugs. More recently, autophagic cell death has been shown to trigger a nonapoptotic cell death program in cancer cells displaying functional defects of caspases. Fenretinide (FenR), a synthetic derivative of retinoic acid, promotes growth inhibition and induces apoptosis in a wide range of tumor cell types. The present study was designed to evaluate the ability of fenretinide to induce caspase-independent cell death and to this aim we used the human mammary carcinoma cell line MCF-7, lacking functional caspase-3 activity. We demonstrated that in these cells fenretinide is able to trigger an autophagic cell death pathway. In particular we found that fenretinide treatment resulted in the increase in Beclin 1 expression, the conversion of the soluble form of LC3 to the autophagic vesicle-associated form LC3-II and its shift from diffuse to punctate staining and finally the increase in lysosomes/autophagosomes. By contrast, caspase-3 reconstituted MCF-7 cell line showed apoptotic cell death features in response to fenretinide treatment. These data strongly suggest that fenretinide does not invariably elicit an apoptotic response but it is able to induce autophagy when apoptotic pathway is deregulated. The understanding of the molecular mechanisms involved in fenretinide action is important for the future design of therapies employing this retinoid in breast cancer treatment.

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Eastern Cooperative Oncology Group, Philadelphia, USA. jsparano@montefiore.org

BACKGROUND: We compared the efficacy of two different taxanes, docetaxel and paclitaxel, given either weekly or every 3 weeks, in the adjuvant treatment of breast cancer. METHODS: We enrolled 4950 women with axillary lymph node-positive or high-risk, lymph node-negative breast cancer. After randomization, all patients first received 4 cycles of intravenous doxorubicin and cyclophosphamide at 3-week intervals and were then assigned to intravenous paclitaxel or docetaxel given at 3-week intervals for 4 cycles or at 1-week intervals for 12 cycles. The primary end point was disease-free survival. RESULTS: As compared with patients receiving standard therapy (paclitaxel every 3 weeks), the odds ratio for disease-free survival was 1.27 among those receiving weekly paclitaxel (P=0.006), 1.23 among those receiving docetaxel every 3 weeks (P=0.02), and 1.09 among those receiving weekly docetaxel (P=0.29) (with an odds ratio >1 favoring the groups receiving experimental therapy). As compared with standard therapy, weekly paclitaxel was also associated with improved survival (odds ratio, 1.32; P=0.01). An exploratory analysis of a subgroup of patients whose tumors expressed no human epidermal growth factor receptor type 2 protein found similar improvements in disease-free and overall survival with weekly paclitaxel treatment, regardless of hormone-receptor expression. Grade 2, 3, or 4 neuropathy was more frequent with weekly paclitaxel than with paclitaxel every 3 weeks (27% vs. 20%). CONCLUSIONS: Weekly paclitaxel after standard adjuvant chemotherapy with doxorubicin and cyclophosphamide improves disease-free and overall survival in women with breast cancer. (ClinicalTrials.gov number, NCT00004125 [ClinicalTrials.gov].). Copyright 2008 Massachusetts Medical Society.

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