This study was aimed to investigate the reversible effect of tetrandrine, toremifene and their combination on multidrug resistance of K562/A02 cell line. The IC(50) (the concentration causing 50% inhibition of cell growth) of adriamycin (ADR) were assayed by MTT method, the expression of MDR1 mRNA was measured by RT-PCR, the concentration of p-glycoprotein (P-gp) and intracellular ADR were detected by flow cytometry. The results showed that the IC(50) of ADR on K562/A02 and K562 cells were 57.43 and 1.16 mg/L, respectively. The IC(50) of ADR on K562/A02 cells after treatment with tetrandrine, toremifene and both combination were 14.12, 20.74 and 9.14 mg/L respectively, but both drugs did not influence the IC(50) of ADR on K562 cells. Pretreating K562/A02 cells with toremifene (2.5 micromol/L), tetrandrine (1 micromol/L) or both for 72 hours partially restored the sensitivity of K562/A02 cells to ADR. Tetrandrine and toremifene (alone or combination) elevated the ADR concentration in K562/A02, down regulated the expressions of P-gp and MDR1 mRNA. It is concluded that multidrug resistance of K562/A02 cells can be partially reversed by tetrandrine or toremifene, the combination of both drugs shows a higher synergistic reversal effect.
Antineoplastic Agents, Hormonal ; pharmacology ; Antineoplastic Agents, Phytogenic ; pharmacology ; Benzylisoquinolines ; pharmacology ; Doxorubicin ; Drug Resistance, Multiple ; drug effects ; Drug Resistance, Neoplasm ; drug effects ; Drug Synergism ; Humans ; K562 Cells ; Toremifene ; pharmacology

AIMTo explore the effect of tamoxifen on voltage-dependent sodium channels in SHG-44 glioma cell line.

METHODSWhole-cell patch clamp technique was used to record the Na currents in SHG-44 cell line and to investigate the effect of tamoxifen of different concentration on this channel currents.

RESULTSThis channel activated and inactivated quickly. Tamoxifen could significantly decrease the amplitude of Na currents of SHG-44 cell line. This block effect was dose dependent and voltage dependent. When the holding potential was 0 mV, 8 micromol/L tamoxifen could block this currents 69%. The half inhibition concentration (IC50) was 5.54 micromol/L.

CONCLUSIONTamoxifen could significantly block the voltage dependent sodium channel in malignant glioma cell line SHG-44. It might be one of the mechanisms that tamoxifen inhibit glioma proliferation. clamp technique was used to record the Na currents in SHG-44 cell line and to investigate the effect of tamoxifen of different concentration on this channel currents.

RESULTSThis channel activated and inactivated quickly. Tamoxifen could significantly decrease the amplitude of Na currents of SHG-44 cell line. This block effect was dose dependent and voltage dependent. When the holding potential was 0 mV, 8 micromol/L tamoxifen could block this currents 69%. The half inhibition concentration (IC50) was 5.54 micromol/L.

CONCLUSIONTamoxifen could signifi-cantly block the voltage dependent sodium channel in malignant glioma cell line SHG-44. It might be one of the mechanisms that tamoxifen inhibit glioma proliferation.

Antineoplastic Agents, Hormonal ; pharmacology ; Brain Neoplasms ; pathology ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Glioma ; pathology ; Humans ; Patch-Clamp Techniques ; Sodium Channel Blockers ; pharmacology ; Tamoxifen ; pharmacology

The effects of estradiol and tamoxifen on the proliferation of estrogen receptor positive cells and the relationship between the tamoxifen tolerance and cell origin were investigated. The tissues of human endometrium and breast cancer were randomly selected following dissection for primary cell culture. After the breast cancer cells and endometrial cells were treated with 1 x 10(-8) mol/L estradiol and/or 1 x 10(-6) tamoxifen, 3H-labelled thymine nucleotide was used to trace the kinetics of cell proliferation. There was no significant difference in the inhibition on the human endometrial cells between tamoxifen-treated group (6.3%) and control group (6.4%), but tamoxifen could significantly inhibit the proliferation of the human breast cancer cells (45.84%) as compared with control group (52.72%). Moreover, tamoxifen could significantly stimulate the proliferation of tamoxifen resistant breast cancer cells (9.64%) as compared with control group (6.32%). Estradiol could significantly stimulate the proliferation of all the three kinds of cells as compare with control group. The combined use of estradiol and tamoxifen could inhibit the proliferation of the endometrial cells and breast cancer cells as compared with estradiol used alone, but on the tamoxifen resistant breast cancer cells, they could more significantly stimulate the proliferation than E2. It was concluded that E2 could stimulate the proliferation of these three kinds of cells. However, the inhibitive effects of tamoxifen on the proliferation of these cells were dependent on the estradiol.
Antineoplastic Agents, Hormonal/*pharmacology ; Breast Neoplasms/*pathology ; Cell Division/drug effects ; Cells, Cultured ; Drug Interactions ; Endometriosis/pathology ; Endometrium/*pathology ; Estradiol/*pharmacology ; Tamoxifen/*pharmacology ; Tumor Cells, Cultured

Antineoplastic Agents, Hormonal ; pharmacology ; Apoptosis ; drug effects ; Cell Cycle ; drug effects ; Cell Proliferation ; drug effects ; Hep G2 Cells ; Humans ; Inhibitor of Apoptosis Proteins ; Microtubule-Associated Proteins ; metabolism ; Tamoxifen ; pharmacology

The in vitro antitumor activity of bakuchiol was exploited, compared with tamoxifen. The result of biological activities showed that bakuchiol could inhibit human breast cancer and the IC50 values were 2.89 x 10(-5) mol L(-1) and 8.29 x 10(-3) mol L(-1) against the cells line T-47D and MDA-MB-231 respectively. On the other hand, the key intermediate to synthesize bakuchiol was obtained by the method of Ireland-Claisen rearrangement. Comparing with traditional Claisen rearrangement, the reaction conditions are milder and the reaction reagents are safer.
Antineoplastic Agents, Hormonal ; pharmacology ; Antineoplastic Agents, Phytogenic ; chemical synthesis ; isolation & purification ; pharmacology ; Breast Neoplasms ; pathology ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Female ; Humans ; Inhibitory Concentration 50 ; Phenols ; chemical synthesis ; isolation & purification ; pharmacology ; Plants, Medicinal ; chemistry ; Psoralea ; chemistry ; Tamoxifen ; pharmacology

OBJECTIVETo study the effect of 17beta-estradiol (17beta-E(2)) and medroxyprogesterone acetate (MPA) on the expression of VEGF mRNA in epithelial ovarian carcinoma cell line in vitro.

METHODSHuman epithelial ovarian carcinoma cell line SKOV3 cells were exposed to 17beta-E(2) (10(-12) approximately 10(-8) mol/L) or MPA (10(-9) approximately 10(-5) mol/L), the expression level of VEGF mRNA was determined by RT-PCR.

RESULTSThe PCR products of VEGF were mainly 606 bp and 474 bp. The expression of VEGF mRNA in the 17beta-E(2)-treated cells was significantly higher than in the untreated control (P < 0.05), the expression level of VEGF mRNA increased with the increase in 17beta-E(2) concentration. The expression of VEGF mRNA in SKOV3 cells treated with MPA (10(-9) approximately 10(-5) mol/L) was significantly lower than in the untreated control (P < 0.05), especially that of 606 bp.

CONCLUSIONEstrogen can up-regulate, while progesterone can down-regulate mRNA expression of VEGF. Further studies are needed to elucidate the mechanism.

Adenocarcinoma ; metabolism ; pathology ; Antineoplastic Agents, Hormonal ; pharmacology ; Cell Line, Tumor ; Dose-Response Relationship, Drug ; Estradiol ; pharmacology ; Female ; Humans ; Medroxyprogesterone Acetate ; pharmacology ; Ovarian Neoplasms ; metabolism ; pathology ; RNA, Messenger ; biosynthesis ; genetics ; Vascular Endothelial Growth Factor A ; biosynthesis ; genetics

The effects of estradiol and tamoxifen on the proliferation of estrogen receptor positive cells and the relationship between the tamoxifen tolerance and cell origin were investigated. The tissues of human endometrium and breast cancer were randomly selected following dissection for primary cell culture. After the breast cancer cells and endometrial cells were treated with 1 x 10(-8) mol/L estradiol and/or 1 x 10(-6) tamoxifen, 3H-labelled thymine nucleotide was used to trace the kinetics of cell proliferation. There was no significant difference in the inhibition on the human endometrial cells between tamoxifen-treated group (6.3%) and control group (6.4%), but tamoxifen could significantly inhibit the proliferation of the human breast cancer cells (45.84%) as compared with control group (52.72%). Moreover, tamoxifen could significantly stimulate the proliferation of tamoxifen resistant breast cancer cells (9.64%) as compared with control group (6.32%). Estradiol could significantly stimulate the proliferation of all the three kinds of cells as compare with control group. The combined use of estradiol and tamoxifen could inhibit the proliferation of the endometrial cells and breast cancer cells as compared with estradiol used alone, but on the tamoxifen resistant breast cancer cells, they could more significantly stimulate the proliferation than E2. It was concluded that E2 could stimulate the proliferation of these three kinds of cells. However, the inhibitive effects of tamoxifen on the proliferation of these cells were dependent on the estradiol.
Adult ; Antineoplastic Agents, Hormonal ; pharmacology ; Breast Neoplasms ; pathology ; Cell Division ; drug effects ; Cells, Cultured ; Drug Interactions ; Endometriosis ; pathology ; Endometrium ; pathology ; Estradiol ; pharmacology ; Female ; Humans ; Middle Aged ; Tamoxifen ; pharmacology ; Tumor Cells, Cultured

OBJECTIVETo observe the expression of ER alpha and SMRT in ER alpha-positive and -negative cell lines before and after treatment with tamoxifen (TAM).

METHODSBreast cancer T47D cells (ER alpha-positive) and MDA-MB-231 cells (ER alpha-negative) were treated with TAM, cell viability was measured by MMT assay before and after TAM treatment. Flow cytometry (FCM) was applied to analyze apoptosis rate and cell cycle. Immunohistochemistry and Western blot were used to test ER alpha and SMRT expression in T-47D and MDA-MB-231 cells with and without TAM treatment.

RESULTProliferation rate of T-47D and MDA-MB-231 decreased after 0.10 mmol/L TAM treatment for 48 h compared with control group (P <0.05), especially that of T47D cells. The result of FCM showed that sub-diploid apoptosis peak was found in both cell lines after TAM treatment. Immunohistochemistry and Western blot indicated that T-47D cells presented ER alpha++ and SMRT++, and ER alpha expression decreased after TAM treatment, meanwhile, that of SMRT increased. MDA-MB-231 cells presented ER alpha-, SMRT-, and both expression levels increased slightly after TAM treatment.

CONCLUSIONTAM can inhibit the proliferation of breast cancer cells by inducing cell apoptosis,which is associated with alteration of ER alpha and SMRT expression.

Antineoplastic Agents, Hormonal ; pharmacology ; Apoptosis ; drug effects ; Breast Neoplasms ; metabolism ; pathology ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Estrogen Receptor alpha ; metabolism ; Female ; Humans ; Nuclear Receptor Co-Repressor 2 ; metabolism ; Selective Estrogen Receptor Modulators ; pharmacology ; Tamoxifen ; pharmacology

BACKGROUND/AIMS: Tamoxifen is a widely used anticancer drug for breast cancer with frequent gastrointestinal side effects. Changes in gastrointestinal motility is associated with altered activities of membrane ion channels. Ion channels have important role in regulating membrane potential and cell excitability. This study was performed to investigate the effects of tamoxifen on the membrane ionic currents in colonic smooth muscle cells. METHODS: Murine colonic smooth muscle cells were isolated from the proximal colon using collagenase, and the membrane currents were recorded using a whole-cell patch clamp technique. RESULTS: Two types of voltage-dependent K+ currents were recorded (A-type and delayed rectifier K+ currents). Tamoxifen inhibited both types of voltage-dependent K+ currents in a dose-dependent manner. However, tamoxifen did not change the half-inactivation potential and the recovery time of voltage-dependent K+ currents. Chelerythrine, a protein kinase C inhibitor or phorbol 12, 13-dibutyrate, a protein kinase C activator did not affect the voltage-dependent K+ currents. Guanosine 5'-O-(2-thio-diphosphate) did not affect the tamoxifen-induced inhibition of voltage-dependent K+ currents. Tamoxifen inhibited voltage-dependent Ca2+ currents completely in whole-test ranges. CONCLUSIONS: These results suggest that tamoxifen can alter various membrane ionic currents in smooth muscle cells and cause some adverse effects on the gastrointestinal motility.
Animals ; Antineoplastic Agents, Hormonal/*pharmacology ; Calcium Channels/drug effects ; Colon/*drug effects/physiology ; English Abstract ; In Vitro ; Membrane Potentials ; Mice ; Myocytes, Smooth Muscle/*drug effects/physiology ; Potassium Channels/*drug effects ; Tamoxifen/*pharmacology

BACKGROUNDCancer stem cells (CSCs) are the cause of cancer recurrence because they are resistant to conventional therapy and contribute to cancer growth and metastasis. Endocrinotherapy is the most common breast cancer therapy and acquired tamoxifen (TAM) resistance is the main reason for endocrinotherapy failure during such therapy. Although acquired resistance to endocrine treatment has been extensively studied, the underlying mechanisms are unclear. We hypothesized that breast CSCs played an important role in TAM-induced resistance during breast cancer therapy. Therefore, we investigated the biological characteristics of TAM-resistant (TAM-R) breast cancer cells.

METHODSMammosphere formation and tumorigenicity of wild-type (WT) and TAM-R MCF7 cells were tested by a mammosphere assay and mouse tumor xenografts respectively. Stem-cell markers (SOX-2, OCT-4, and CD133) and epithelial-mesenchymal transition (EMT) markers were tested by quantitative real-time (qRT)-PCR. Morphological observation was performed to characterize EMT.

RESULTSAfter induction of TAM resistance, TAM-R MCF7 cells exhibited increased proliferation in the presence of TAM compared to that of WT MCF7 cells (P < 0.05), indicating enhanced TAM resistance of TAM-R MCF7 cells compared to that of WT MCF7 cells. TAM-R MCF7 cells showed enhanced mammosphere formation and tumorigenicity in nude mice compared to that of WT MCF7 cells (P < 0.01), demonstrating the elevated CSC properties of TAM-R MCF7 cells. Consistently, qRT-PCR revealed that TAM-R MCF7 cells expressed increased mRNA levels of stem cell markers including SOX-2, OCT-4, and CD133, compared to those of WT MCF7 cells (P < 0.05). Morphologically, TAM-R MCF7 cells showed a fibroblastic phenotype, but WT MCF7 cells were epithelial-like. After induction of TAM resistance, qRT-PCR indicated that MCF7 cells expressed increased mRNA levels of Snail, vimentin, and N-cadherin and decreased levels of E-cadherin, which are considered as EMT characteristics (P < 0.05).

CONCLUSIONTAM-R MCF7 cells possess CSC characteristics and may be responsible for TAM resistance during breast cancer therapy.

Animals ; Antineoplastic Agents, Hormonal ; pharmacology ; Breast Neoplasms ; drug therapy ; pathology ; Drug Resistance, Neoplasm ; Epithelial-Mesenchymal Transition ; Female ; Humans ; MCF-7 Cells ; Mice ; Neoplastic Stem Cells ; drug effects ; Tamoxifen ; pharmacology