shikonin and Breast-Neoplasms

Shikonin is a natural multipotent anti-tumorigenic compound. We investigated potential synergy between shikonin and anti-diabetic metformin against tumorigenic properties of breast cancer cell line MCF-7.. Shikonin and metformin synergize in inhibiting the tumorigenic activities of MCF-7 cells including their proliferation, invasiveness, and EMT with a potential to inhibit multidrug resistance.

Topics: Apoptosis; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Epithelial-Mesenchymal Transition; Female; Humans; MCF-7 Cells; Metformin; Naphthoquinones

Recognition of a new therapeutic agent may activate an alternative programmed cell death for the treatment of breast cancer.. Here, it has been tried to evaluate the effects of Shikonin, a naphthoquinone derivative of Lithospermum erythrorhizon, on the induction of necroptosis and apoptosis mediated by RIPK1-RIPK3 in the ER+ breast cancer cell line, MCF-7.. In the current study, cell death modalities, cell cycle patterns, RIPK1 and RIPK3 expressions, caspase-3 and caspase-8 activities, reactive oxygen species and mitochondrial membrane potential have been evaluated in the Shikonin-treated MCF-7 cells.. Necroptosis and apoptosis have been occurred by Shikonin, with a significant increase in RIPK1 and RIPK3 expressions, although necroptosis was the major rout in MCF-7 cells. Shikonin significantly increased the percentage of the cells in sub-G1 and also those in the later stages of cell cycle, which represents an increase in necroptosis and apoptosis. Under caspase inhibition by Z-VAD-FMK, Shikonin has stimulated necroptosis, which could be arrested by Nec-1. An increase in ROS levels and a decrease in the mitochondrial membrane potential have also been observed.. On the basis of present findings, Shikonin has been suggested as a good candidate for the induction of cell death in ER+ breast cancer, although further investigations, experimental and clinical, are required.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Cycle; Cell Death; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Female; Humans; MCF-7 Cells; Membrane Potential, Mitochondrial; Molecular Structure; Naphthoquinones; Reactive Oxygen Species; Receptors, Estrogen; Structure-Activity Relationship; Tumor Cells, Cultured

Shikonin (SHK) has been proven to have a good anti-tumor effect. However, poor water solubility and low bioavailability limit its wide application in clinical practice. In this study, to overcome these drawbacks, RGD-modified shikonin-loaded liposomes (RGD-SSLs-SHK) were successfully prepared. It exhibited excellent physicochemical characteristics including particle size, zeta potential, encapsulation efficiency, and delayed release time. Meanwhile, the targeting activity of the RGD-modified liposomes was demonstrated by flow cytometry and confocal microscopy in the α

Topics: Apoptosis; bcl-2-Associated X Protein; Breast Neoplasms; Cell Adhesion; Cell Movement; Cell Proliferation; Female; Gene Expression Regulation, Neoplastic; Humans; Liposomes; MCF-7 Cells; Naphthoquinones; Oligopeptides; Proto-Oncogene Proteins c-bcl-2; Transcription Factor RelA

Shikonin is a naphthoquinone isolated from the dried root of Lithospermum erythrorhizon, an herb used in Chinese medicine. Although several studies have indicated that shikonin exhibits antitumor activity in breast cancer, the mechanism of action remains unclear. In the present study, we performed transcriptome analysis using RNA-seq and explored the mechanism of action of shikonin in regulating the growth of different types of breast cancer cells. The IC

Topics: Apoptosis; Breast Neoplasms; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Dual Specificity Phosphatase 1; Dual Specificity Phosphatase 2; Gene Expression Profiling; Humans; Lithospermum; MAP Kinase Signaling System; MCF-7 Cells; Naphthoquinones; RNA; Signal Transduction; Transcriptome

The Chinese traditional medicine Shikonin is an ideal drug due to its multiple targets to tumor cells. But in clinics, improving its aqueous solubility and tumor accumulation is still a challenge. Herein, a copolymer with tunable poly(N-isopropylacrymaide) and polylactic acid block lengths is designed, synthesized, and characterized in nuclear magnetic resonance. The corresponding thermosensitive nanomicelle (TN) with well-defined core-shell structure is then assembled in an aqueous solution. For promoting the therapeutic index, the physical-chemistry properties of TNs including narrow size, low critical micellar concentration, high serum stability, tunable volume phase transition temperature (VPTT), high drug-loading capacity, and temperature-controlled drug release are systematically investigated and regulated through the fine self-assembly. The shikonin is then entrapped in a degradable inner core resulting in a shikonin-loaded thermosensitive nanomicelle (STN) with a VPTT of ~40°C. Compared with small-molecular shikonin, the in vitro cellular internalization and cytotoxicity of STN against breast cancer cells (Michigan Cancer Foundation-7) are obviously enhanced. In addition, the therapeutic effect is further enhanced by the programmed cell death (PCD) specifically evoked by shikonin. Interestingly, both the proliferation inhibition and PCD are synergistically promoted as T > VPTT, namely the temperature-regulated passive targeting. Consequently, as intravenous injection is administered to the BALB/c nude mice bearing breast cancer, the intratumor accumulation of STNs is significantly increased as T > VPTT, which is regulated by the in-house developed heating device. The in vivo antitumor assays against breast cancer further confirm the synergistically enhanced therapeutic efficiency. The findings of this study indicate that STN is a potential effective nanoformulation in clinical cancer therapy.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Delayed-Action Preparations; Drugs, Chinese Herbal; Female; Humans; Hyperthermia, Induced; MCF-7 Cells; Mice, Inbred BALB C; Micelles; Nanostructures; Naphthoquinones; Polyesters; Polymers; Solubility; Temperature; Tissue Distribution; Xenograft Model Antitumor Assays

The signal transducer and activator of transcription 3 is a constitutively activated oncogenic protein in various human tumors and represents a valid target for anticancer drug design. In this study, we have achieved a new type of STAT3 inhibitors based on structural modifications on shikonin scaffold, guided by computational modelling. By tests, PMMB-187 exhibited a more outstanding profile than shikonin on a small panel of human breast cancer cells, especially for the MDA-MB-231 cells. For the cellular mechanisms research, PMMB-187 was found to induce cell apoptosis in MDA-MB-231 cells, associated with the reduction of mitochondrial membrane potential, production of ROS and alteration of the levels of apoptosis-related proteins. Furthermore, PMMB-187 inhibited constitutive/inducible STAT3 activation, transcriptional activity, nuclear translocation and downstream target genes expression in STAT3-dependent breast cancer cells MDA-MB-231. Besides, no obvious inhibitory effect on activation of STAT1 and STAT5 was observed with PMMB-187 treatment. Most notably, the in vivo studies further revealed that PMMB-187 could dramatically suppress the MDA-MB-231 cells xenografted tumor growth. The in vitro and in vivo results collectively suggest that PMMB-187 may serve as a promising lead compound for the further development of potential therapeutic anti-neoplastic agents.

Topics: Antineoplastic Agents; Apoptosis; Breast Neoplasms; Cell Line, Tumor; Female; Humans; Membrane Potential, Mitochondrial; Models, Molecular; Molecular Structure; Naphthoquinones; STAT3 Transcription Factor; Thiadiazoles

Immunogenic cell death (ICD) of tumor cells occurs via various pathways that activate immune cell systems against cancer. Previous studies have demonstrated that shikonin (SK), a plant secondary metabolite, can confer strong pharmacological activities that activate ICD and strong immunogenicity of tumor cells. However, the exact hierarchical regulatory mechanisms including the molecular targets of SK-activated immunogenicity are still unknown. Here, the heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) was revealed to serve as a specific protein target for SK. This binding plays a key role in SK-stimulated ICD activity and the suppression of post-transcriptional mRNA processing, including nuclear export activity of newly synthesized mRNAs in mammary carcinoma cells in vitro. Moreover, it also mechanistically mediates the anti-metastatic effect of a tumor cell lysate (TCL) vaccine, which can be readily generated from SK-treated 4T1 tumor cells (SK-TCL), and the derived tumor-immunogenicity of SK-TCL-treated dendritic cells in vivo. Together, the identification of hnRNPA1 as the intracellular molecular target provides compelling pharmacology-based knowledge for the potential clinical use of SK-induced immunogenicity. In addition, SK may also serve as a potent suppressor that interferes with specific post-transcriptional activities, a mechanism which may be useful for exploitation in cancer therapeutics.

Topics: Animals; Antineoplastic Agents; Apoptosis; Breast Neoplasms; Cancer Vaccines; Cell Line, Tumor; Dendritic Cells; Female; Heterogeneous Nuclear Ribonucleoprotein A1; Humans; Mice; Mice, Inbred BALB C; Molecular Docking Simulation; Naphthoquinones; RNA Processing, Post-Transcriptional; RNA, Messenger; Tandem Mass Spectrometry; Xenograft Model Antitumor Assays

Shikonin is a naphthoquinone isolated from the traditional Chinese medicine Lithospermum. It has been used in the treatment of various tumors. However, the effects of shikonin on such diseases have not been fully elucidated. In the present study, we detected the exosome release of a breast cancer cell line (MCF-7) with shikonin treatment and found a positive relationship between the level of secreted exosomes and cell proliferation. We next analyzed miRNA profiles in MCF-7 cells and exosomes and found that some miRNAs are specifically sorted and abundant in exosomes. Knockdown of the most abundant miRNAs in exosomes and the MCF-7 proliferation assay showed that miR-128 in exosomes negatively regulates the level of Bax in MCF-7 recipient cells and inhibits cell proliferation. These results show that shikonin inhibits the proliferation of MCF-7 cells through reducing tumor-derived exosomal miR-128. The current study suggests that shikonin suppresses MCF-7 growth by the inhibition of exosome release.

Topics: Apoptosis; Breast Neoplasms; Cell Proliferation; Exosomes; Female; Gene Expression Regulation, Neoplastic; Humans; MCF-7 Cells; MicroRNAs; Naphthoquinones

The tumor microenvironment plays a critical role in regulating breast tumor progression. Signaling between preadipocytes and breast cancer cells has been found to promote breast tumor formation and metastasis. Exosomes secreted from preadipocytes are important components of the cancer stem cell niche. Mouse preadipocytes (3T3L1) are treated with the natural antitumor compound shikonin (SK) and exosomes derived from mouse preadipocytes are co-cultured with MCF10DCIS cells. We examine how preadipocyte-derived exosomes can regulate early-stage breast cancer via regulating stem cell renewal, cell migration, and tumor formation. We identify a critical miR-140/SOX2/SOX9 axis that regulates differentiation, stemness, and migration in the tumor microenvironment. Next, we find that the natural antitumor compound SK can inhibit preadipocyte signaling inhibiting nearby ductal carcinoma in situ (DCIS) cells. Through co-culture experiments, we find that SK-treated preadipocytes secrete exosomes with high levels of miR-140, which can impact nearby DCIS cells through targeting SOX9 signaling. Finally, we find that preadipocyte-derived exosomes promote tumorigenesis in vivo, providing strong support for the importance of exosomal signaling in the tumor microenvironment. Our data also show that targeting the tumor microenvironment may assist in blocking tumor progression.

Topics: 3T3 Cells; Adipocytes; Animals; Antineoplastic Agents; Breast Neoplasms; Cell Differentiation; Cell Line, Tumor; Coculture Techniques; Exosomes; Female; Gene Expression Regulation, Neoplastic; Humans; Mice; MicroRNAs; Naphthoquinones; Neoplasm Transplantation; Neoplastic Stem Cells; Signal Transduction; SOX9 Transcription Factor

Cancer stem cells (CSCs) are responsible for aggressive tumor growth, metastasis and therapy resistance. In this study, we evaluated the effects of Shikonin (Shk) on breast cancer and found its anti-CSC potential. Shk treatment decreased the expression of various epithelial to mesenchymal transition (EMT) and CSC associated markers. Kinase profiling array and western blot analysis indicated that Shk inhibits STAT3, FAK and Src activation. Inhibition of these signaling proteins using standard inhibitors revealed that STAT3 inhibition affected CSCs properties more significantly than FAK or Src inhibition. We observed a significant decrease in cell migration upon FAK and Src inhibition and decrease in invasion upon inhibition of STAT3, FAK and Src. Combined inhibition of STAT3 with Src or FAK reduced the mammosphere formation, migration and invasion more significantly than the individual inhibitions. These observations indicated that the anti-breast cancer properties of Shk are due to its potential to inhibit multiple signaling proteins. Shk also reduced the activation and expression of STAT3, FAK and Src in vivo and reduced tumorigenicity, growth and metastasis of 4T1 cells. Collectively, this study underscores the translational relevance of using a single inhibitor (Shk) for compromising multiple tumor-associated signaling pathways to check cancer metastasis and stem cell load.

Topics: Adult; Anti-Inflammatory Agents, Non-Steroidal; Breast Neoplasms; Cell Movement; Cell Proliferation; Cell Survival; Drugs, Chinese Herbal; Epithelial-Mesenchymal Transition; Female; Focal Adhesion Kinase 1; Humans; MCF-7 Cells; Middle Aged; Naphthoquinones; Neoplasm Invasiveness; Neoplastic Stem Cells; Proto-Oncogene Proteins pp60(c-src); Signal Transduction; Spheroids, Cellular; STAT3 Transcription Factor; Tumor Burden; Tumor Cells, Cultured

Shikonin (SK), a natural naphthoquinone isolated from the Chinese medicinal herb, has been known to suppress the proliferation of several cancer cells. However, its role in the epithelial mesenchymal transition (EMT) has yet to be demonstrated. The aim of the present study was to examine the effects of SK on EMT. Lipopolysaccharide (LPS) induced EMT-like phenotypic changes, enhancing cell migration and invasion. SK markedly reduced the expression of the LPS-induced EMT markers, including N-cadherin in MDA-MB‑231 cells, and increased the expression of E-cadherin in MCF-7 cells. SK also inhibited cell migration and invasion in vitro. The effects of SK on the LPS-induced EMT were mediated by the inactivation of the NF-κB-Snail signaling pathway. The results provided new evidence that SK suppresses breast cancer cell invasion and migration by inhibiting the EMT. Therefore, SK is a potentially effective anticancer agent for breast tumors, by inhibiting metastasis.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Blotting, Western; Breast Neoplasms; Cadherins; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Drugs, Chinese Herbal; Epithelial-Mesenchymal Transition; Female; Humans; Lipopolysaccharides; MCF-7 Cells; Microscopy, Fluorescence; Naphthoquinones; Snail Family Transcription Factors; Transcription Factor RelA; Transcription Factors

Breast cancer, the most common cancer in the women, is the leading cause of death. Necrotic signaling pathways will enable targeted therapeutic agents to eliminate apoptosis-resistant cancer cells. In the present study, the effect of shikonin on the induction of cell necroptosis or apoptosis was evaluated using the T-47D breast cancer cell line. The cell death modes, caspase-3 and 8 activities and the levels of reactive oxygen species (ROS) were assessed. Cell death mainly occurred through necroptosis. In the presence of Nec-1, caspase-3 mediated apoptosis was apparent in the shikonin treated cells. Shikonin stimulates ROS generation in the mitochondria of T-47D cells, which causes necroptosis or apoptosis. Induction of necroptosis, as a backup-programmed cell death pathway via ROS stimulation, offers a new strategy for the treatment of breast cancer.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Breast Neoplasms; Caspase 3; Cell Proliferation; Female; Humans; Mitochondria; Naphthoquinones; Necrosis; Reactive Oxygen Species; Tumor Cells, Cultured

Shikonin, a small-molecule natural product which inhibits the activity of pyruvate kinase M2 (PKM2), has been studied as an anti-cancer drug candidate in human cancer models. Here, our results demonstrate that shikonin is able to sensitize human breast cancer cells to chemotherapy by paclitaxel (taxol). Human breast adenocarcinoma MBA-MD-231 cells, which have higher levels of PKM2 expression and activity compared with MCF-7 cells, were selected to study further. The concentrations of shikonin and taxol were first selected at which they did not significantly induce cytotoxicity when treated alone, whereas the combination induced apoptosis. Surprisingly, PKM2 activity was decreased by shikonin, but not by the combination treatment. To identify the potential targets of this combination, human phospho-kinase antibody array analysis was performed and results indicated that the combination treatment inhibited the activation of ERK, Akt, and p70S6 kinases, which are known to contribute to breast cancer progression. Finally, how the combination affects breast cancer cell growth in vivo was tested using a xenograft tumor model. The results indicated that shikonin plus taxol prolonged animal survival and reduced tumor size than the vehicle treatment group. In summary, our results suggest that shikonin has a potential as an adjuvant for breast cancer therapy.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Apoptosis; Breast Neoplasms; Cell Line, Tumor; Drug Interactions; Drug Therapy, Combination; Female; Heterografts; Humans; Mice; Mice, Nude; Naphthoquinones; Paclitaxel

Shikonin, a natural naphthoquinone isolated from a traditional Chinese medicinal herb, has been reported to promote tumor cell death. However, there are few reports concerning its effect on metastasis-related cell invasion and migration behavior. In the present study, we investigated the effect of shikonin on human breast cancer invasion and migration. We found that shikonin inhibited phorbol 12-myristate 13-acetate (PMA)-induced cell migration and invasion in MCF-7 breast cancer cells, which was correlated with modulation of matrix metalloproteinase-9 (MMP-9) through suppression of both expression and proteolytic and promoter activity. We also found that shikonin inhibited both MMP-9 expression and promoter activity in MDA-MB‑231 cells with high metastatic potential. These results indicated that shikonin induces the suppression of migration and invasion through modulation of MMP-9 in human breast cancer cells. Therefore, shikonin may be a potential anticancer drug for human breast cancer therapy.

Topics: Breast Neoplasms; Cell Movement; Female; Gene Expression Regulation, Neoplastic; Humans; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; MCF-7 Cells; Naphthoquinones; Neoplasm Invasiveness; Signal Transduction; Tetradecanoylphorbol Acetate

Glutathione-S-transferase (GST) is a cytoplasmic protein responsible for detoxification, but the effect of the enzyme on cell biological events, including proliferation and migration, has never been reported. Thus, we evaluated the detoxification effect of in vitro-applied GST on cancer cell proliferation and migration. Assays for proliferation and migration of human breast cancer cells in the presence of GST were carried out. Binding of GST on the surface of the cancer cells was studied by flow cytometry. Detoxification through GST pathway was studied in the presence of shikonin. The effective dosage of GST in enhancement of cell proliferation was 10-50 nM, and the cell migration could be significantly enhanced after 6 hours in the presence of 2-50 nM GST. Therefore, overall cell proliferation and migration could be enhanced in the presence of 10nM or greater concentration of GST, and 15 μM shikonin-induced toxification of the cancer cells could be neutralized by 1.0 μM GST. Flow cytometry showed that GST directly bound to the surface of the cancer cells, and this was confirmed by fluorescence confocal microscopic observation. It is concluded that human class π-GST enhances proliferation and migration of human breast cancer cells by means of direct binding to the cell surface and maintaining cell viability by detoxification.

Topics: Breast Neoplasms; Cell Death; Cell Line, Tumor; Cell Membrane; Cell Movement; Cell Proliferation; Cell Survival; Female; Flow Cytometry; Glutathione Transferase; Humans; Metabolic Detoxication, Phase II; Microscopy, Confocal; Naphthoquinones; Protein Binding; Recombinant Proteins

Shikonin (SK) has been isolated and identified as a key bioactive component in an herbal plant, Shikon (gromwell). In this study, we investigated antiestrogen activity of SK in breast cancer cells. In human breast cancer cells, we observed that treatment with SK inhibits tumor cell growth in estrogen receptor alpha (ERalpha)-positive, but not ERalpha-negative breast cancer cells. Estrogen-dependent cell growth was inhibited by co-treatment with SK. A potential molecular mechanism by which SK inhibits estrogen action was explored. We found that SK has no effect on ERalpha mRNA expression, but decreases its protein level. This effect is associated with an increase in ubiquitinated ERalpha for degradation. Our results suggest that SK downregulates ERalpha protein through a proteasome-mediated pathway. We also found that the treatment with SK inhibits estrogen-induced estrogen response elements reporter gene activity. Furthermore, SK inhibits recruitment of ERalpha at the estrogen-dependent gene promoters, and subsequently suppresses gene expression. Finally, co-treatment with SK enhanced sensitivity of breast cancer cells to endocrine therapy. Collectively, our studies suggested that SK has a potential for antihormone therapy in ERalpha-positive breast cancer cells, and should serve as a target for new drug developments.

Topics: Breast Neoplasms; Cell Line, Tumor; Chromatin Immunoprecipitation; Estrogen Receptor alpha; Estrogen Receptor Modulators; Female; Gene Expression; Humans; Immunoblotting; Naphthoquinones; Response Elements; Reverse Transcriptase Polymerase Chain Reaction; Transcription, Genetic

Exposure to higher levels of estrogen produces genotoxic metabolites that can stimulate mammary tumorigenesis. Induction of NF-E2-related factor 2 (NRF2)-dependent detoxifying enzymes (e.g., NAD(P)H-quinone oxidoreductase 1 (NQO1)) is considered an important mechanism of protection against estrogen-associated carcinogenesis because they would facilitate removal of toxic estrogens. Here, we studied the impact of estrogen-receptor (ER) signaling on NRF2-dependent gene transcription. In luciferase assay experiments using the 5-flanking region of the human NQO1 gene promoter, we observe that ERα ligand-binding domain (LBD) is required for estrogen inhibition of NQO1 promoter activity in estrogen-dependent breast cancer cells. Chromatin immunoprecipitation (ChIP) assay shows that estrogen recruits ERα and a class III histone deacetylase SIRT1 at the NQO1 promoter, leading to inhibition of NQO1 transcription. Inhibition of ERα expression by the antiestrogen shikonin reverses the inhibitory effect of estrogen on NQO1 expression. As a consequence, a chemoprevention study was undertaken to monitor the impact of shikonin on DNA lesions and tumor growth. Treatment of MCF-7 breast cancer cells with shikonin inhibits estrogen-induced 8-hydroxy-2-deoxyguanosine (8-OHdG), a marker of DNA damage. NQO1 deficiency promotes estrogen-dependent tumor formation, and shikonin inhibits estrogen-dependent tumor growth in an NQO1-dependent manner in MCF-7 xenografts. These results suggest that estrogen-receptor signaling pathway has an inhibitory effect on NRF2-dependent enzymes. Moreover, shikonin reverses the inhibitory effects of estrogen on this pathway and may contribute to breast cancer prevention.

Topics: Animals; Antineoplastic Agents, Phytogenic; Binding Sites; Breast Neoplasms; Cell Line, Tumor; Chromatin Immunoprecipitation; DNA Damage; Dose-Response Relationship, Drug; Estradiol; Estrogen Receptor alpha; Female; Gene Expression Regulation, Neoplastic; Humans; Mice; Mice, Nude; NAD(P)H Dehydrogenase (Quinone); Naphthoquinones; NF-E2-Related Factor 2; Ovariectomy; Promoter Regions, Genetic; RNA, Messenger; Signal Transduction; Sirtuin 1; Transcription, Genetic; Transfection; Tumor Burden; Xenograft Model Antitumor Assays

A series of shikonin analogues with side chain variants have been synthesized and evaluated for antitumor activity. These novel analogues show a broad spectrum of in vitro cytotoxicity against various cancer cell lines. Additionally, some analogues were also found to have the ability to decrease the expression level of HIF-1alpha in breast cancer cells MDA-MB-231 under hypoxia. The features of these analogues suggest their potential in cancer therapy.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Chemistry, Pharmaceutical; Drug Design; Drug Screening Assays, Antitumor; HeLa Cells; HL-60 Cells; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Inhibitory Concentration 50; Models, Chemical; Naphthoquinones

Steroid sulfatase (STS) has an important role in regulating the biosynthesis of estrogen within breast tumors. We aimed to investigate whether shikonin, an ingredient of Lithospermum erythrorhizon, could modulate STS expression in breast cancer cells. By MTT assay, shikonin inhibited the cell proliferation of breast cancer cells MCF-7 and SK-BR-3. Moreover, by semi-quantitative/quantitative reverse transcription polymerase chain reaction and dual-luciferase reporter based bioluminescent measurements, the mRNA and enzymatic activity levels of STS were decreased after shikonin treatment. Concluding, shikonin could act as a selective estrogen enzyme modulator by down-regulating the STS expression.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Down-Regulation; Female; Gene Expression Regulation, Enzymologic; Humans; Lithospermum; Naphthoquinones; RNA, Messenger; Steryl-Sulfatase

Shikonin, isolated from the plant Lithospermum erythrorhizon Sieb. Et Zucc, has been reported to induce apoptosis in several tumor cells. However, such effect of shikonin on human breast cancer cells has not been reported. Thus, in the present study, whether shikonin could induce MCF-7 human breast cancer cell apoptosis was investigated. The results showed that shikonin (2.5-80 microM) induced MCF-7 cell death in a time- and dose-dependent manner, as measured by MTT assay. The IC(50) of a 24 h, 48 h and 72 h time course for MCF-7 cells was 7.4+/-0.4, 6.3+/-0.6 and 3.9+/-0.5 microM, respectively. Cellular morphology observation showed that MCF-7 cells underwent marked apoptotic morphological changes upon treatment with 10 microM shikonin compared with the untreated control. Flow cytometric analysis of shikonin-treated MCF-7 cells showed that the ratio of the apoptotic DNA fragmentation increased in a dose-dependent manner. The present study demonstrated for the first time that the cytotoxic effect of shikonin on MCF-7 cells underwent apoptosis process.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Breast Neoplasms; Cell Proliferation; DNA Fragmentation; DNA, Neoplasm; Dose-Response Relationship, Drug; Female; Flow Cytometry; Humans; Naphthoquinones; Tumor Cells, Cultured