BACKGROUND/AIMS: MiRNA-301a-3p is an oncogenic miRNA whose expression is associated with tumor development, metastases and overall poor prognosis. Estrogen receptor α (ERα) is one of the estrogen hormone-activated transcription factors, which regulates a large number of genes and is involved in the mammary gland development. Expression of ERα is considered to be a good indicator for endocrine therapy and breast cancer survival. Loss of ERα in breast cancer patients indicates invasiveness and poor prognosis. In this study, we focus on the regulation of ERα by miR-301a and its role in transition from estrogen-dependent to estrogen-independent breast cancer. METHODS: Expression of miR-301a-3p was measured by qRT-PCR in tumor tissue samples from 111 patients with primary breast carcinoma and in mammospheres representing in vitro model of cancer stem-like cells. Dual reporter luciferase assay and complementary experiments were performed to validate ESR1 as a direct target of miR-301a-3p. The effect of miR-301a-3p on estrogen signaling was evaluated on the level of gene and protein expression and growth response to estrogens. Finally, the effect of miR-301a-3p expression on tumor growth was studied in nude mice. RESULTS: We identified ESR1 as a direct target of miR-301a-3p. Ectopic miR-301a-3p causes a decrease in ESR1 mRNA and protein level and modulates the expression of ERα target genes in ERα positive breast cancer cells. Consistently, miR-301a-3p causes a decrease in sensitivity of MCF7 cells to 17β-estradiol and inhibits the growth of estrogen dependent tumor in nude mice. Yet, the mice tumors have significantly increased expression of genes related to cancer stem-like cells and epithelial to mesenchymal transition suggesting enrichment of the population of cells with more invasive properties, in line with our observation that miR-301a-3p expression is highly increased in mammospheres which show a decrease in estrogenic signaling. Importantly, miR-301a-3P level is also increased in primary breast cancer samples exhibiting an ER/PR negative phenotype. CONCLUSION: Our results confirm ESR1 as a direct target of miR-301a-3p and suggest that miR-301a-3p likely contributes to development of estrogen independence, which leads to a more invasive phenotype of breast cancer.

• MeSH
• 3' nepřekládaná oblast MeSH
• alfa receptor estrogenů analýza   genetika   metabolismus   MeSH
• estrogeny metabolismus   MeSH
• lidé MeSH
• mikro RNA genetika   MeSH
• myši inbrední BALB C MeSH
• myši nahé MeSH
• nádorové buněčné linie MeSH
• nádory prsu genetika   metabolismus   patologie   MeSH
• regulace genové exprese u nádorů * MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

AIMS: Expression of the HER2 oncogene in breast cancer is associated with resistance to treatment, and Her2 may regulate bioenergetics. Therefore, we investigated whether disruption of the electron transport chain (ETC) is a viable strategy to eliminate Her2(high) disease. RESULTS: We demonstrate that Her2(high) cells and tumors have increased assembly of respiratory supercomplexes (SCs) and increased complex I-driven respiration in vitro and in vivo. They are also highly sensitive to MitoTam, a novel mitochondrial-targeted derivative of tamoxifen. Unlike tamoxifen, MitoTam efficiently suppresses experimental Her2(high) tumors without systemic toxicity. Mechanistically, MitoTam inhibits complex I-driven respiration and disrupts respiratory SCs in Her2(high) background in vitro and in vivo, leading to elevated reactive oxygen species production and cell death. Intriguingly, higher sensitivity of Her2(high) cells to MitoTam is dependent on the mitochondrial fraction of Her2. INNOVATION: Oncogenes such as HER2 can restructure ETC, creating a previously unrecognized therapeutic vulnerability exploitable by SC-disrupting agents such as MitoTam. CONCLUSION: We propose that the ETC is a suitable therapeutic target in Her2(high) disease. Antioxid. Redox Signal. 26, 84-103.

• MeSH
• antitumorózní látky chemie   farmakologie   MeSH
• biologické markery MeSH
• buněčná smrt účinky léků   MeSH
• buněčné dýchání účinky léků   MeSH
• cílená molekulární terapie MeSH
• elektronový transportní řetězec antagonisté a inhibitory   chemie   metabolismus   MeSH
• inhibiční koncentrace 50 MeSH
• lidé MeSH
• membránový potenciál mitochondrií účinky léků   MeSH
• mitochondrie účinky léků   metabolismus   MeSH
• molekulární konformace MeSH
• molekulární modely MeSH
• nádorové buněčné linie MeSH
• nádory prsu farmakoterapie   metabolismus   patologie   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• receptor erbB-2 antagonisté a inhibitory   metabolismus   MeSH
• respirační komplex I antagonisté a inhibitory   chemie   metabolismus   MeSH
• tamoxifen farmakologie   MeSH
• vazba proteinů MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

• Publikační typ
• abstrakt z konference MeSH

We report that tumor cells without mitochondrial DNA (mtDNA) show delayed tumor growth, and that tumor formation is associated with acquisition of mtDNA from host cells. This leads to partial recovery of mitochondrial function in cells derived from primary tumors grown from cells without mtDNA and a shorter lag in tumor growth. Cell lines from circulating tumor cells showed further recovery of mitochondrial respiration and an intermediate lag to tumor growth, while cells from lung metastases exhibited full restoration of respiratory function and no lag in tumor growth. Stepwise assembly of mitochondrial respiratory (super)complexes was correlated with acquisition of respiratory function. Our findings indicate horizontal transfer of mtDNA from host cells in the tumor microenvironment to tumor cells with compromised respiratory function to re-establish respiration and tumor-initiating efficacy. These results suggest pathophysiological processes for overcoming mtDNA damage and support the notion of high plasticity of malignant cells.

• MeSH
• citrátsynthasa metabolismus   MeSH
• elektronový transportní řetězec metabolismus   MeSH
• energetický metabolismus MeSH
• homologní transplantace MeSH
• melanom experimentální patologie   MeSH
• messenger RNA metabolismus   MeSH
• mitochondriální DNA metabolismus   MeSH
• mitochondrie genetika   metabolismus   ultrastruktura   MeSH
• myši inbrední BALB C MeSH
• myši inbrední C57BL MeSH
• myši inbrední NOD MeSH
• myši SCID MeSH
• myši MeSH
• NADH-dehydrogenasa genetika   metabolismus   MeSH
• nádorové buněčné linie MeSH
• nádory plic patologie   sekundární   MeSH
• proliferace buněk MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

AIMS: To assess the effect of mitochondrially targeted vitamin E (VE) analogs on mitochondrial function and biogenesis. RESULTS: Mitochondrially targeted vitamin E succinate (MitoVES) is an efficient inducer of apoptosis in cancer cells. Here, we show that unlike its untargeted counterpart α-tocopheryl succinate, MitoVES suppresses proliferation of cancer cells at sub-apoptotic doses by way of affecting the mitochondrial DNA (mtDNA) transcripts. We found that MitoVES strongly suppresses the level of the displacement loop transcript followed by those of mtDNA genes coding for subunits of mitochondrial complexes. This process is coupled to the inhibition of mitochondrial respiration, dissipation of the mitochondrial membrane potential, and generation of reactive oxygen species. In addition, exposure of cancer cells to MitoVES led to decreased expression of TFAM and diminished mitochondrial biogenesis. The inhibition of mitochondrial transcription was replicated in vivo in a mouse model of HER2(high) breast cancer, where MitoVES lowered the level of mtDNA transcripts in cancer cells but not in normal tissue. INNOVATION: Our data show that mitochondrially targeted VE analogs represent a novel class of mitocans that not only induce apoptosis at higher concentrations but also block proliferation and suppress normal mitochondrial function and transcription at low, non-apoptogenic doses. CONCLUSIONS: Our data indicate a novel, selective anti-cancer activity of compounds that act by targeting mitochondria of cancer cells, inducing significant alterations in mitochondrial function associated with transcription of mtDNA-coded genes. These changes subsequently result in the arrest of cell proliferation.

• MeSH
• alfa-tokoferol farmakologie   MeSH
• apoptóza účinky léků   MeSH
• buněčné dýchání účinky léků   MeSH
• lidé MeSH
• membránový potenciál mitochondrií účinky léků   MeSH
• mitochondriální DNA metabolismus   MeSH
• mitochondrie účinky léků   fyziologie   MeSH
• myši transgenní MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• nádory metabolismus   MeSH
• proliferace buněk účinky léků   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• receptor erbB-2 genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The mitochondrial respiratory chain is organized into dynamic high molecular weight complexes that associate to form supercomplexes. The function of these SCs is to minimize the production of reactive oxygen species (ROS) generated during electron transfer within them and to efficiently transfer electrons to complex IV. These supra-molecular structures as well as whole mitochondria are stress-responsive and respond to mitochondrially targeted anti-cancer agent by destabilization and induction of massive production of ROS leading to apoptosis. We have recently developed mitochondrially targeted anti-cancer agents epitomized by the mitochondrially targeted analogue of the redox-silent compound vitamin E succinate, which belongs to the group of agents that kill cancer cells via their mitochondria-destabilizing activity, referred to as mitocans. To understand the molecular mechanism of the effect of such agents, the use of native blue gel electrophoresis and clear native electrophoresis coupled with in-gel activity assays, are methods of choice. The relevant methodology is described in this chapter.

• MeSH
• antitumorózní látky farmakologie   MeSH
• elektronový transportní řetězec antagonisté a inhibitory   MeSH
• frakcionace buněk MeSH
• lidé MeSH
• mitochondriální proteiny metabolismus   MeSH
• mitochondrie účinky léků   metabolismus   MeSH
• transport elektronů účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• Publikační typ
• abstrakt z konference MeSH

• Publikační typ
• abstrakt z konference MeSH

Flavone eupatorin is one of the constituents of Orthosiphon stamineus, a medicinal herb used in folk medicine in South East Asia for treatment of various disorders. In our study, we investigated the antiproliferative properties of a chloroform extract of the leaves of O. stamineus and of pure eupatorin. The compound was able to reduce the number of viable cancer cells to the same extent as the extract, with IC(50) values in micromolar range. Moreover, both the eupatorin standard and the extract caused cells to arrest in the G2/M phase of the cell cycle. This clearly demonstrates that eupatorin contributes significantly to the overall extract activity. Induction of mitotic catastrophe, accompanied by key molecular events defining apoptosis, is the mechanism of eupatorin-induced cell death. Importantly, eupatorin (at the doses cytotoxic to cancer cells) did not kill normal cells; it only limited migration of HUVEC endothelial cells and their ability to create tubes. The ability of eupatorin to nonspecifically inhibit many protein kinases was proven and is the probable cause of its cellular effects. In summary, eupatorin emerges as a promising agent in anticancer research.

• MeSH
• antitumorózní látky fytogenní farmakologie   terapeutické užití   MeSH
• apoptóza účinky léků   MeSH
• endoteliální buňky pupečníkové žíly (lidské) MeSH
• flavonoidy farmakologie   terapeutické užití   MeSH
• flavony farmakologie   terapeutické užití   MeSH
• fytoterapie MeSH
• inhibiční koncentrace 50 MeSH
• inhibitory angiogeneze farmakologie   terapeutické užití   MeSH
• kontrolní body buněčného cyklu účinky léků   MeSH
• lidé MeSH
• listy rostlin MeSH
• Orthosiphon chemie   MeSH
• pohyb buněk účinky léků   MeSH
• proliferace buněk účinky léků   MeSH
• proteinkinasy metabolismus   MeSH
• rostlinné extrakty farmakologie   terapeutické užití   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH