Project description:Tamoxifen is the treatment of choice in estrogen receptor alpha breast cancer patients. However, ~50% of ERα-positive tumors exhibit intrinsic or rapidly acquire resistance to endocrine treatment, requiring chemotherapy. Ιt has been difficult to predict de novo resistance to endocrine therapy and/or assess the likelihood of early relapse, while no concrete mechanism regulating the acquisition and the maintenance of endocrine resistance has been identified. We have performed a whole transcriptome analysis of an ER-positive (T47D) and a triple-negative (MDA-MBA-231) breast cancer cell line exposed to tamoxifen for a short time frame (hours) in order to study resistance mechanisms that are initiated early after initiation of tamoxifen treatment. Cells after a 4h incubation with medium containing 10% charcoal stripped FBS were incubated with vehicle,E2 (10-6M) or tamoxifen (10-6M) in RPMI 1640 supplemented with 10% charcoal stripped FBS, for 3 hours. Total RNA was isolated using Nucleospin II columns (Macheray-Nagel, Dttren, Germany), according to the manufacturer’s instructions. RNA was labeled and hybridized according to the Affymetrix protocol (Affymetrix Gene-Chip Expression Analysis Technical Manual), using the HGU133A plus 2 chip, analyzing a total of 54675 transcripts. Signals were detected by an Affymetrix microarray chip reader.
Project description:Tamoxifen is the treatment of choice in estrogen receptor alpha breast cancer patients. However, ~50% of ERM-NM-1-positive tumors exhibit intrinsic or rapidly acquire resistance to endocrine treatment, requiring chemotherapy. M-NM-^Yt has been difficult to predict de novo resistance to endocrine therapy and/or assess the likelihood of early relapse, while no concrete mechanism regulating the acquisition and the maintenance of endocrine resistance has been identified. We have performed a whole transcriptome analysis of an ER-positive (T47D) and a triple-negative (MDA-MBA-231) breast cancer cell line exposed to tamoxifen for a short time frame (hours) in order to study resistance mechanisms that are initiated early after initiation of tamoxifen treatment. Cells after a 4h incubation with medium containing 10% charcoal stripped FBS were incubated with vehicle,E2 (10-6M) or tamoxifen (10-6M) in RPMI 1640 supplemented with 10% charcoal stripped FBS, for 3 hours. Total RNA was isolated using Nucleospin II columns (Macheray-Nagel, Dttren, Germany), according to the manufacturerM-bM-^@M-^Ys instructions. RNA was labeled and hybridized according to the Affymetrix protocol (Affymetrix Gene-Chip Expression Analysis Technical Manual), using the HGU133A plus 2 chip, analyzing a total of 54675 transcripts. Signals were detected by an Affymetrix microarray chip reader.
Project description:Tamoxifen is the treatment of choice in estrogen receptor alpha breast cancer patients. However, ~50% of ERα-positive tumors exhibit intrinsic or rapidly acquire resistance to endocrine treatment, requiring chemotherapy. Ιt has been difficult to predict de novo resistance to endocrine therapy and/or assess the likelihood of early relapse, while no concrete mechanism regulating the acquisition and the maintenance of endocrine resistance has been identified. We have performed a whole transcriptome analysis of an ER-positive (T47D) and a triple-negative (MDA-MBA-231) breast cancer cell line exposed to tamoxifen for a short time frame (hours) in order to study resistance mechanisms that are initiated early after initiation of tamoxifen treatment.
Project description:Currently the greatest challenge in oncology is the lack of homogeneity of the lesions where different cell components respond differently to treatment. There is growing consensus that monotherapies are insufficient to eradicate the disease and there is an unmet need for more potent combinatorial treatments. We have previously shown that hypericin photodynamic therapy (HYP-PDT) triggers electron transport chain (ETC) inhibition in cell mitochondria. We have also shown that tamoxifen (TAM) enhances cytotoxicity in cells with high respiration, when combined with ETC inhibitors. Herein we introduce a synergistic treatment based on TAM chemotherapy and HYP-PDT. We tested this novel combinatorial treatment (HYPERTAM) in two metabolically different breast cancer cell lines, the triple-negative MDA-MB-231 and the estrogen-receptor-positive MCF7, the former being quite sensitive to HYP-PDT while the latter very responsive to TAM treatment. In addition, we investigated the mode of death, effect of lipid peroxidation, and the effect on cell metabolism. The results were quite astounding. HYPERTAM exhibited over 90% cytotoxicity in both cell lines. This cytotoxicity was in the form of both necrosis and autophagy, while high levels of lipid peroxidation were observed in both cell lines. We, consequently, translated our research to an in vivo pilot study encompassing the MDA-MB-231 and MCF7 tumor models in NOD SCID-γ immunocompromised mice. Both treatment cohorts responded very positively to HYPERTRAM, which significantly prolonged mice survival. HYPERTAM is a potent, synergistic modality, which may lay the foundations for a novel, composite anticancer treatment, effective in diverse tumor types.