retinaldehyde and Breast-Neoplasms

According to cancer stem cell theory, only a limited number of self-renewing and cloning cells are responsible for tumor relapse after a period of remittance. The aim of the present study was to investigate the effects of Doxorubicin and α-Mangostin, two antiproliferative drugs, on both tumor bulk and stem cells in multicellular tumor spheroids originated from the luminal MCF-7 breast cancer cell line. A new and original fluorimetric assay was used to selectively measure the activity of the retinaldehyde-dependent isoenzymes of aldehyde dehydrogenase (RALDH), which are markers of a subpopulation of breast cancer stem cells. The administration of 5 μg/ml (12.2 μM) α-Mangostin for 48 h provoked: i) a marked disaggregation of the spheroids, leading to a doubling of their volume (p < 0.01), ii) a 40 % decrease in cell viability (p < 0.01), evaluated by the acid phosphatase assay, and iii) a reduction by more than 90 % of RALDH activity. By contrast, Doxorubicin given for 48 h in the range of 0.1-40 μM did not significantly reduce cell viability and caused only a modest modification of the spheroid morphology. Moreover, 40 μM Doxorubicin increased RALDH activity 2.5-fold compared to the untreated sample. When the two drugs were administered together using 5 μg/ml α-Mangostin, the IC

Topics: Aldehyde Dehydrogenase; Antineoplastic Combined Chemotherapy Protocols; Breast Neoplasms; Cell Survival; Dose-Response Relationship, Drug; Doxorubicin; Female; Humans; Inhibitory Concentration 50; MCF-7 Cells; Neoplastic Stem Cells; Retinaldehyde; Spheroids, Cellular; Xanthones

Evoking tumor cellular senescence, an irreversible status of cell growth quiescence, has been recently proposed as a potential strategy to improve the efficacy of cancer treatment. In the current study, all-trans retinal, the precursor of all-trans retinoic acid, was conjugated to dextran via hydrazone bond to generate amphiphilic dextran-retinal (DR) conjugates, which self-assembled into pH-sensitive DR micelles. Our results showed that DR micelles moderately inhibited MCF-7 breast cancer cell growth through inducing p21-associated cellular senescence, which relied on retinoic acid receptors (RARs) and was accompanied by significant G0/G1 cell cycle arrest. Moreover, DR micelles were capable of encapsulating doxorubicin (DOX) to generate DOX-loaded DD micelles, facilitating the uptake and release of DOX in cancer cells. Compared with free DOX, DD micelles more effectively suppressed tumor growth and prolonged survival time of mouse xenograft model through inducing tumor apoptosis and cellular senescence. However, blocking cellular senescence diminished DD-caused apoptosis in MCF-7 cells by 40-50%. Therefore, pH-sensitive DR micelles not only served as a potent platform for DOX delivery, but also enhanced the anti-tumor effect of DOX by inducing tumor cellular senescence. These data reveal a great potential of evoking tumor senescence with retinal-conjugated micelles for boosting breast cancer chemotherapy.

Topics: Animals; Antineoplastic Agents; Apoptosis; Breast Neoplasms; Cell Proliferation; Cell Survival; Cellular Senescence; Dextrans; Doxorubicin; Endocytosis; Female; Humans; Hydrogen-Ion Concentration; MCF-7 Cells; Mice, Inbred BALB C; Mice, Nude; Micelles; Receptors, Retinoic Acid; Retinaldehyde; Tissue Distribution

9-Cis-retinoic acid (RA) suppresses cancer cell proliferation via binding and activation of nuclear receptors, retinoid X receptors (RXRs). In vivo, 9-cis-RA is formed through oxidation of 9-cis-retinol by cis-retinol dehydrogenase (cRDH), an enzyme that we characterized previously. Since 9-cis-RA is a potent inhibitor of breast cancer cell proliferation, we hypothesized that overexpression of cRDH in breast cancer cells would result in increased production of 9-cis-RA, which in turn would suppress cell proliferation. To investigate this hypothesis, MCF7 human breast carcinoma cells were transduced with cRDH cDNA (LRDHSN/MCF7), and the growth kinetics and retinoid profiles of cells were examined following treatment with 9-cis-retinol. LRDHSN/MCF7 cells showed a marked reduction in cell numbers (60-80%) upon treatment with 9-cis-retinol compared to vehicle alone. Within 24 h of treatment, approximately 75% of the 9-cis-retinol was taken up and metabolized by LRDHSN/MCF7 cells. Despite the rapid uptake and oxidation of 9-cis-retinol to 9-cis-retinal, 9-cis-RA was not formed in these cells. We detect at least one novel metabolite formed from both 9-cis-retinol and 9-cis-retinal that may play a role in inhibition of MCF7 cell proliferation. Our studies demonstrate that 9-cis-retinol in combination with cRDH inhibits breast cancer cell proliferation by production of retinol metabolites other than RA.

Topics: Alcohol Oxidoreductases; Breast Neoplasms; Cell Proliferation; Diterpenes; Female; Humans; Retinaldehyde; Retinoid X Receptors; Tumor Cells, Cultured

The human breast tumor cell line was separated by Percoll density gradient centrifugation into six different subpopulations, A to F, one of which (E) appears to contain the stem cells on the basis of several criteria (M. Resnicoff et al. 1987, Proc. Natl. Acad. Sci. USA 84, 7295. We now analyzed the response of the isolated subpopulations to insulin, thrombin, PGF2 alpha, estradiol, and 13-cis-retinal. We demonstrate that the first two growth factors stimulate [3H]thymidine incorporation in the more differentiated subpopulations (D and F), while PGF2 alpha has mitogenic activity in subpopulations C and D. In the absence of any added growth factor, estradiol has the extreme and transient capacity of allowing the stem cell to detach from the tissue culture dish and to grow in suspension as multicellular aggregates (MCF-7/SE cells). 13-cis-Retinal acts as a negative modulator of differentiation and protects the cells from the inhibitory and differentiation activity of Na-butyrate.

Topics: Breast Neoplasms; Butyrates; Butyric Acid; Cell Differentiation; Cell Division; Cell Survival; Culture Media; Dinoprost; Diterpenes; DNA; Estradiol; Hormones; Humans; Insulin; Neoplastic Stem Cells; Retinaldehyde; Retinoids; Thrombin; Tumor Cells, Cultured

The human mammary tumor cells MCF-7 show enhanced proliferation when treated with low doses (10(-8)-10(-7) M) of 13-cis Retinal (a vitamin A derivative). These results are independent of the growth medium used. We describe a novel effect of 13-cis Retinal: the increased synthesis and accumulation of nuclear proteins in chronically treated cells. The cytoplasmic proteins and proteins released to the culture medium are transiently and oppositly modified. Moreover, chronic treated cells have growth advantages over the untreated counterparts in a clonogenic soft agar assay.

Topics: Breast Neoplasms; Cell Division; Cell Line; Cell Nucleus; Female; Humans; Kinetics; Neoplasm Proteins; Nucleoproteins; Retinaldehyde; Retinoids