Hypoxia induced paclitaxel resistance in human ovarian cancers via hypoxia-inducible factor 1alpha.
ABSTRACT Chemoresistance severely restricts the anti-cancer medicines from effectively treating human ovarian cancer, which has been shown to develop and survive in the specific hypoxic environments. To understand the relationship between hypoxia and chemoresistance, we investigated the potential role of hypoxia in the pathophysiology of chemoresistance, especially focusing on hypoxia-inducible factor 1alpha (HIF-1alpha).
The A2780 ovarian cancer cells are cultured in gradient hypoxic conditions (5% O(2), 3% O(2), and 1% O(2)), the sensitivity of the cells to paclitaxel and the cell inhibitory rate were determined by MTT assay. The expression and the transcriptional activity of HIF-1alpha were examined by western blot, Immunocytochemical staining, reverse transcription-polymerase chain reaction (RT-PCR), and the dual luciferase reporter system, respectively. The cell cycle distribution was analyzed by flow cytometry. In addition, we silence HIF-1alpha expression by performing RNA interference.
MTT assay demonstrates that hypoxic challenge substantially reduces the susceptibility of cells to paclitaxel at all the tested concentrations. Coincident with this is the activation of HIF-1alpha in nuclear, which displays the increased transcriptional activity and high protein expression. Hypoxic manipulation (5% O(2), approximately 1% O(2)) significantly increased the cell population at G0/G1. Interestingly, knockdown of endogenous HIF-1alpha significantly alleviates the chemoresistance and promotes G1/S transition with the increased sensitivity of A2780 cells to paclitaxel under each hypoxic condition.
It suggests that HIF-1alpha, stimulated by hypoxia, exerts a pivotal role in chemoresistance by G0/G1 arrest. Eliminating hypoxic conditions or silencing HIF-1alpha by siRNA might provide a potent tool to enhance paclitaxel effectiveness in treatment of human ovarian cancer.
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ABSTRACT: Objectives: To investigate whether hypoxia has an effect on regulation of multidrug resistance (MDR) to chemotherapeutic drugs in laryngeal carcinoma cells and explore the role of hypoxia-inducible factor-1α (HIF- 1α). Methods: Laryngeal cancer cells were cultured under normoxic and hypoxic conditions. The sensitivity of the cells to multiple drugs and levels of apoptosis induced by paclitaxel were determined by MTT assay and annexin-V/propidium iodide staining analysis, respectively. HIF-1α expression was blocked by RNA interference. The expression of HIF-1α gene was detected by real-time quantitative RT-PCR and Western blotting. The value of fluorescence intensity of intracellular adriamycin accumulation and retention in cells was evaluated by flow cytometry. Results: The sensitivity to multiple chemotherapy agents and induction of apoptosis by paclitaxel could be reduced by hypoxia (P<0.05). A the same time, the adriamycin releasing index of cells was increased (P<0.05). However, resistance acquisition subject to hypoxia in vitro was suppressed by down-regulating HIF-1α expression. Conclusion: HIF-1α could be considered as a key regulator for mediating hypoxia-induced MDR in laryngeal cancer cells via inhibition of drug-induced apoptosis and decrease in intracellular drug accumulation.Asian Pacific journal of cancer prevention: APJCP 08/2013; 14(8):4853-4858. DOI:10.7314/APJCP.2013.14.8.4853 · 1.50 Impact Factor
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ABSTRACT: Development of a targeted polymeric gene delivery system is essential for reducing the non-specific uptake and toxicity of the gene carriers. In this study, we have tested the specificity of the cell penetrating peptide (DS 4-3), screened by phage display technique, towards metastatic breast cancer cells. This peptide has shown specificity towards metastatic breast cancer cells, which was confirmed through endocytosis inhibition study. Furthermore, the DS 4-3 peptide was conjugated to bPEI, to deliver the therapeutic miR-145. Tumor suppressor miR-145 inhibited tumor cell growth, and significantly suppressed cell invasion. The DS 4-3 peptide conjugated branched PEI (DSbPEI)/pLuc nanoparticles showed increased transfection in malignant murine breast cancer cells at the neutral surface charge (N/P molar ratio of 3), compared to scramble peptide conjugated bPEI/pLuc nanoparticles, without causing any cytotoxicity. This specific increase in transfection with DS-bPEI/pLuc nanoparticles was not found in the cancer cells that originated from different tissue, such as HeLa cervical cancer cells, or in the normal cells, such as NIH-3T3 murine fibroblast cells. Thus, the specific transfection of miR-145 in metastatic breast cancer cells mediated by DS-bPEI resulted in enhanced reduction in proliferation.Macromolecular Research 11/2013; 21(11). DOI:10.1007/s13233-013-1161-z · 1.68 Impact Factor
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ABSTRACT: Hypoxia within the tumour microenvironment is correlated with poor treatment outcome after radiation and chemotherapy, and with decreased overall survival in cancer patients. Several molecular mechanisms by which hypoxia supports tumour growth and interferes with effective radiation and chemotherapies are now well established. However, several new lines of investigation are pointing to yet another ominous outcome of hypoxia in the tumour microenvironment: suppression of anti-tumour immune effector cells and enhancement of tumour escape from immune surveillance. This review summarises this important information, and highlights mechanistic data by which hypoxia incapacitates several different types of immune effector cells, enhances the activity of immunosuppressive cells and provides new avenues which help 'blind' immune cells to detect the presence of tumour cells. Finally, we discuss data which indicates that mild thermal therapy, through its physiologically regulated ability to alter vascular perfusion and oxygen tensions within the tumour microenvironment, as well as its ability to enhance the function of some of the same immune effector activities that are inhibited by hypoxia, could be used to rapidly and safely release the tight grip of hypoxia in the tumour microenvironment thereby reducing barriers to more effective immune-based therapies.International Journal of Hyperthermia 01/2010; 26(3):232-46. DOI:10.3109/02656731003601745 · 2.77 Impact Factor