کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2132740 1086714 2007 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Confluence-dependent resistance to doxorubicin in human MDA-MB-231 breast carcinoma cells requires hypoxia-inducible factor-1 activity
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی تحقیقات سرطان
پیش نمایش صفحه اول مقاله
Confluence-dependent resistance to doxorubicin in human MDA-MB-231 breast carcinoma cells requires hypoxia-inducible factor-1 activity
چکیده انگلیسی
Compared with tumour cells cultured as sparse monolayers, tumour cells cultured as confluent monolayers exhibit high levels of resistance to anti-cancer agents. This phenomenon is called confluence-dependent resistance (CDR). We determined the contribution of hypoxia-inducible factor-1 (HIF-1), a key transcriptional regulator of cellular adaptations to hypoxia, to the development of CDR in MDA-MB-231 breast cancer cells. Clonogenic assays revealed a density-dependent increase in resistance to doxorubicin. Cell density also correlated with increased staining for reductively activated pimonidazole (a marker for hypoxia), as well as with increased levels of the HIF-1α subunit and HIF transcriptional activity as determined by immunocytochemistry, Western blot, and luciferase reporter assays. Importantly, inhibition of HIF-1α expression with siRNA significantly attenuated CDR. Similarly, shaking of cultures attenuated CDR, pimonidazole immunostaining, HIF-1α accumulation, and HIF-1 transcriptional activity. Having established a link between HIF-1 and CDR, we used HIF-1α and HIF-1 transcriptional activity as markers to investigate the role of additional factors in the regulation of CDR. Confluence-dependent increases in HIF-1α accumulation and HIF-1 transcriptional activity were observed even in cells cultured at 0.1% O2 as well as in sparse cultures incubated with conditioned medium from confluent monolayers. Serum deprivation in both sparse and confluent cultures also resulted in HIF-1α accumulation. These results reveal that, although pericellular hypoxia may be a major contributor to HIF-1 activity, changes in the levels of soluble factors may also play a role. This study demonstrates that HIF-1 is required for CDR.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Experimental Cell Research - Volume 313, Issue 5, 10 March 2007, Pages 867-877
نویسندگان
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