Akt and XIAP regulate the sensitivity of human uterine cancer cells to cisplatin,doxorubicin and taxol

We have investigated the interrelationship between two anti-apoptotic factors, XIAP and Akt, and their role in chemoresistance of uterine cancer cells. We used one cervical cancer cell line (HeLa) and two endometrial cancer cell lines (KLE and Ishikawa) as a model. The three drugs decreased Akt and XIAP content and induced apoptosis in P-Akt-negative HeLa cells. In P-Akt1/3-positive Ishikawa cells apoptosis induction correlated with XIAP decrease. P-Akt1/2/3-positive KLE cells showed maximum chemoresistance as XIAP and Akt levels/phosphorylation remained stable in response to the three drugs, and only cisplatin could significantly induce apoptosis. We found that XIAP and Akt were functionally linked in uterine cancer cells, as downregulation of XIAP with RNAi decreased P-Akt levels, and inhibition of PI3-K/Akt activity using LY294002 decreased XIAP content. Overexpression of constitutively active Akt isoforms in HeLa cells induced isoform-specific sensitivity to doxorubicin and taxol but not cisplatin. XIAP RNAi increased the cell-specific sensitivity to cisplatin and doxorubicin but not taxol. Finally, we found P-Akt immunoreactivity in epithelial cells from multiple human endometrial carcinoma tumors, suggesting that Akt may also regulate chemosensitivity in uterine cancers in vivo. Altogether these results highlight an intertwined role for specific Akt isoforms and XIAP in chemoresistance of uterine cancer cells.     

APR-246 overcomes resistance to cisplatin and doxorubicin in ovarian cancer cells

Two main causes of platinum resistance are mutation in the tumor suppressor gene TP53 and drug-induced increase in intracellular glutathione concentration. Mutations in TP53 occur in about 50% of human tumors. APR-246 (PRIMA-1^MET) is the first clinical-stage compound that reactivates mutant p53 and induces apoptosis. APR-246 is a prodrug that is converted to the active compound methylene quinuclidinone (MQ), a Michael acceptor that binds to cysteine residues in mutant p53 and restores its wild-type conformation. Here, we show that MQ also binds to cysteine in glutathione, thus decreasing intracellular free glutathione concentration. We also show that treatment with APR-246 completely restores the cisplatin and doxorubicin sensitivity to p53-mutant drug-resistant ovarian cancer cells. We propose that this unique ability of APR-246/MQ to bind to cysteines in both mutant p53 and glutathione has a key role in the resensitization as well as in the outstanding synergistic effects observed with APR-246 in combination with platinum compounds in ovarian cancer cell lines and primary cancer cells. However, MQ binding to cysteines in other targets, for example, thioredoxin reductase, may contribute as well. Strong synergy was also observed with the DNA-damaging drugs doxorubicin and gemcitabine, while additive effects were found with the taxane docetaxel. Our results provide a strong rationale for the ongoing clinical study with APR-246 in combination with platinum-based therapy in patients with p53-mutant recurrent high-grade serous (HGS) ovarian cancer. More than 96% of these patients carry TP53 mutations. Combined treatment with APR-246 and platinum or other DNA-damaging drugs could allow dramatically improved therapy of a wide range of therapy refractory p53 mutant tumors.APR-246 (also called PRIMA-1^MET) is the first compound in clinical development that reactivates mutant p53 in cancer cells by promoting its correct wild-type (wt) folding, thus triggering apoptosis.^{1, 2} The lead compound of APR-246, PRIMA-1, was originally discovered by Bykov et al.³ APR-246 showed a good safety profile in a Phase I/II clinical dose-finding study on hematological malignancies and prostate cancer and both clinical and p53-dependent biological responses were observed.⁴ A Phase Ib/II Proof of Concept study with APR-246 in combination with platinum-based therapy, in patients with recurrent p53-mutant high-grade serous (HGS) ovarian cancer, is ongoing. More than 96% of patients with HGS ovarian carcinoma carry TP53 mutations.⁵Platinum-based drugs have an important role in the treatment of many solid tumors including ovarian cancer. Cisplatin, the first drug of this class, has had a major impact in treatment of cancer but is also associated with severe adverse effects like nephrotoxicity. This prompted the development of the less toxic analog carboplatin.⁶ The primary mechanism of action of platinum compounds is adduct formation with nucleophilic groups in tumor cell DNA. This triggers the DNA damage response pathway, in which p53 has a key role, leading to cell-cycle arrest, senescence and/or apoptosis.⁷Patients with ovarian cancer often respond well to the first-line platinum-based chemotherapy, but the majority of the patients with advanced stage tumors relapse and eventually die of chemotherapy-refractory disease. Platinum resistance is most often associated with decreased platinum levels at the site of action (i.e., DNA) and/or failure to trigger the DNA damage response after adduct formation.^{6, 7} The underlying molecular mechanisms of resistance to platinum compounds are multifactorial, involving drug-induced increase in cellular glutathione (GSH) levels leading to enhanced efflux of platinum compounds, reduced drug uptake, increased drug inactivation and DNA adduct repair, as well as inactivation of the tumor suppressor protein p53.^{7, 8, 9, 10} Mutation in p53 is one of the main mechanisms for inhibiting propagation of the DNA damage signal to the apoptotic machinery. About 50% of all tumors carry mutant p53 (see p53.free.fr, 2015) and cancer cells with defects in p53 are in general more resistant to conventional chemotherapy. In many tumors, including ovarian cancer, p53 mutations are correlated to shortened time to progression and decreased patient survival time.^{11, 12} Thus, restoration of wt function of p53 is a promising strategy for cancer therapy.^{13, 14}Here, we describe a new aspect of therapeutic activity of APR-246. APR-246 not only reactivates p53 but also decreases intracellular glutathione levels in a dose-dependent manner. Moreover, APR-246 completely restored cisplatin and doxorubicin sensitivity to mutant p53-carrying resistant ovarian cancer cells. Our results may open possibilities for greatly improved treatment of a wide range of platinum-resistant tumors.     

Synergistic anticancer effects of lectin and doxorubicin in breast cancer cells

We studied the effects, either combined or alone, of lectin from Korean mistletoe (Viscum album var. coloratum agglutinin, VCA) and doxorubicin (DOX) in MCF-7 (estrogen receptor-positive) and MDA-MB231 (estrogen receptor-negative) human breast cancer cells. When VCA and DOX were combined, a strong synergistic effect was shown in cell growth inhibition, compared to VCA or DOX treatment alone. In quantitative apoptosis studies analyzed by flow cytometry, a combination of two agents showed an increase in apoptosis in both cells, compared to agents alone. Also, pro-apoptotic proteins including Bax, Bik, and Puma were increased in both cells, and the survival factor Bcl-2 was inhibited in MCF-7 cells when drugs were combined. Furthermore, VCA combined with DOX mediated S phase arrest, accompanied with a decrease of cell number at G0/G1 phase. This suggests that VCA and DOX combination may possibly lead to a novel strategy for the treatment of breast cancer.     

Amphotericin B potentiates the anticancer activity of doxorubicin on the MCF-7 breast cancer cells

Despite the improvements in cancer treatment, breast cancer still remains the second most common cause of death from cancer in women. Doxorubicin (DOXO) is widely used for cancer treatment. However, drug resistance limits the treatment outcome. Here, we investigated the toxicity of DOXO in combination with an antifungal agent amphotericin B (AmB) against the MCF-7 breast cancer cell line. The cell viability was measured using MTT assay. The apoptosis was studied by caspase-8 and caspase-9 activity measurements and DNA fragmentation was investigated by TUNEL assay. The combination of two drugs significantly increased the apoptotic index and the caspase-8 and caspase-9 activities in comparison to DOXO-treated cells. Our finding showed that pre-treatment of MCF-7 cells with AmB synergistically exerted the anticancer effect of DOXO through the caspase-dependent apoptosis manner.     

Quantification of long-term doxorubicin response dynamics in breast cancer cell lines to direct treatment schedules

While acquired chemoresistance is recognized as a key challenge to treating many types of cancer, the dynamics with which drug sensitivity changes after exposure are poorly characterized. Most chemotherapeutic regimens call for repeated dosing at regular intervals, and if drug sensitivity changes on a similar time scale then the treatment interval could be optimized to improve treatment performance. Theoretical work suggests that such optimal schedules exist, but experimental confirmation has been obstructed by the difficulty of deconvolving the simultaneous processes of death, adaptation, and regrowth taking place in cancer cell populations. Here we present a method of optimizing drug schedules in vitro through iterative application of experimentally calibrated models, and demonstrate its ability to characterize dynamic changes in sensitivity to the chemotherapeutic doxorubicin in three breast cancer cell lines subjected to treatment schedules varying in concentration, interval between pulse treatments, and number of sequential pulse treatments. Cell populations are monitored longitudinally through automated imaging for 600–800 hours, and this data is used to calibrate a family of cancer growth models, each consisting of a system of ordinary differential equations, derived from the bi-exponential model which characterizes resistant and sensitive subpopulations. We identify a model incorporating both a period of growth arrest in surviving cells and a delay in the death of chemosensitive cells which outperforms the original bi-exponential growth model in Akaike Information Criterion based model selection, and use the calibrated model to quantify the performance of each drug schedule. We find that the inter-treatment interval is a key variable in determining the performance of sequential dosing schedules and identify an optimal retreatment time for each cell line which extends regrowth time by 40%-239%, demonstrating that the time scale of changes in chemosensitivity following doxorubicin exposure allows optimization of drug scheduling by varying this inter-treatment interval.     

Cytokinetic effects of carboplatin and cisplatin on a human ovarian cancer cell line

The cytokinetic effects of carboplatin(CBDCA) on a human ovarian cancer cell line(KF-1) were examined by means of cell survival rate and flow cytometry in comparison with cisplatin(CDDP). CBDCA and CDDP exhibited dose dependent cytotoxicity on KF-1, and CBDCA showed compatible cell growth inhibition to that of 15 times concentration of CDDP in comparison with IC50 of 72 hrs after drug addition. From the analysis of cell cycle, CBDCA and CDDP inhibited cell cycle progression at G2 + M phase. CBDCA exhibited G2 + M phase block to that of 15 to 20 times the concentration of CDDP. We suggested that CBDCA had potential therapeutic activity against ovarian cancer, but should be evaluated carefully in the clinical use.     

Oleanolic acid increases the anticancer potency of doxorubicin in pancreatic cancer cells

Combination therapy is a novel cancer therapy approach that combines two or more chemotherapy drugs. This treatment modality enhances the efficacy of chemotherapy by targeting key pathways in an additive or synergistic manner. Therefore, we investigated the efficacy of combination therapy by widely used chemotherapy drug doxorubicin (DOX) and oleanolic acid (OA) to induction of apoptosis for pancreatic cancer (PC) therapy. The effects of DOX, OA, and their combination (DOX-OA) were investigated on proliferation and viability of PC cell line (PANC-1) by MTT assay. Moreover, migration and invasion of the cancer cells were evaluated by trans-well migration assay and wound healing assay. Flow cytometry and DAPI (4′,6-diamidino-2-phenylindole) staining were employed to investigate apoptosis quantification and qualification of the treated cancer cells. Finally, mRNA expression of apoptosis-related genes was assessed by quantitative real-time polymerase chain reaction. Our results demonstrated that the proliferation and metastasis potential of PC cells significantly decreased after treatment by DOX, OA, and DOX-OA. Moreover, we observed an increase in apoptosis percentage in the treated cancer cells. The apoptosis-related gene expression was modified to increase the apoptosis rate in all of the treatment groups. However, the anticancer potency of DOX-OA combination was significantly more than that of DOX and OA treatments alone. Our study suggested that DOX-OA combination exerts more profound anticancer effects against PC cell lines than DOX or OA monotherapy. This approach may increase the efficiency of chemotherapy and reduce unintended side effects by lowering the prescribed dose of DOX.     

2DG enhances the susceptibility of breast cancer cells to doxorubicin

2DG causes cytotoxicity in cancer cells by disrupting thiol metabolism while Doxorubicin (DOX) induces cytotoxicity in tumor cells by generating reactive oxygen species (ROS). Here we examined the combined cytotoxic action of 2DG and DOX in rapidly dividing T47D breast cancer cells vs. slowly growing MCF-7 breast cancer cells. T47D cells exposed to the combination of 2DG/DOX significantly decreased cell survival compared to controls, while 2DG/DOX had no effect on MCF-7 cells. 2DG/DOX also disrupted the oxidant status of T47D treated cells, decreased intracellular total glutathione and increased glutathione disulfide (%GSSG) compared to MCF-7 cells. Lipid peroxidation increased in T47D cells treated with 2DG and/or DOX, but not in MCF-7 cells. T47D cells were significantly protected by NAC, indicating that the combined treatment exerts its action by increasing ROS production and disrupting antioxidant stores. When we inhibited glutathione synthesis with BSO, T47D cells became more sensitive to 2DG/DOX-induced cytotoxicity, but NAC significantly reversed this cytotoxic effect. Finally, 2DG/DOX, and BSO significantly increased the %GSSG in T47D cells, an effect which was also reversed by NAC. Our results suggest that exposure of rapidly dividing breast cancer cells to 2DG/DOX enhances cytotoxicity via oxidative stress and via disruptions to thiol metabolism.     

Dihydroartemisinin induces apoptosis and sensitizes human ovarian cancer cells to carboplatin therapy

The present study was designed to determine the effects of artemisinin (ARS) and its derivatives on human ovarian cancer cells, to evaluate their potential as novel chemotherapeutic agents used alone or in combination with a conventional cancer chemotherapeutic agent, and to investigate their underlying mechanisms of action. Human ovarian cancer cells (A2780 and OVCAR-3), and immortalized non-tumourigenic human ovarian surface epithelial cells (IOSE144), were exposed to four ARS compounds for cytotoxicity testing. The in vitro and in vivo antitumour effects and possible underlying mechanisms of action of dihydroartemisinin (DHA), the most effective compound, were further determined in ovarian cancer cells. ARS compounds exerted potent cytotoxicity to human ovarian carcinoma cells, with minimal effects on non-tumourigenic ovarian surface epithelial (OSE) cells. DHA inhibited ovarian cancer cell growth when administered alone or in combination with carboplatin, presumably through the death receptor- and, mitochondrion-mediated caspase-dependent apoptotic pathway. These effects were also observed in in vivo ovarian A2780 and OVCAR-3 xenograft tumour models. In conclusion, ARS derivatives, particularly DHA, exhibit significant anticancer activity against ovarian cancer cells in vitro and in vivo , with minimal toxicity to non-tumourigenic human OSE cells, indicating that they may be promising therapeutic agents for ovarian cancer, either used alone or in combination with conventional chemotherapy.     

iTRAQ-based proteomic profiling of breast cancer cell response to doxorubicin and TRAIL

Breast cancer is a molecularly heterogeneous disease, and predicting response to chemotherapy remains a major clinical challenge. To minimize adverse side-effects or cumulative toxicity in patients unlikely to benefit from treatment, biomarkers indicating treatment efficacy are critically needed. iTRAQ labeling coupled with multidimensional LC-MS/MS of the enriched mitochondria and endoplasmic reticulum fraction, key organelles regulating apoptosis, has led to the discovery of several differentially abundant proteins in breast cancer cells treated with the chemotherapeutic agent doxorubicin followed by the death receptor ligand, TRAIL, among 571 and 801 unique proteins identified in ZR-75-1 and MDA-MB-231 breast cancer cell lines, respectively. The differentially abundant proteins represent diverse biological processes associated with cellular assembly and organization, molecular transport, oxidative stress, cell motility, cell death, and cancer. Despite many differences in molecular phenotype between the two breast cancer cell lines, a comparison of their subproteomes following drug treatment revealed three proteins displaying common regulation: PPIB, AHNAK, and SLC1A5. Changes in these proteins, detected by iTRAQ, were confirmed by immunofluorescence, visualized by confocal microscopy. These novel potential biomarkers may have clinical utility for assessing response to cancer treatment and may provide insight into new therapeutic targets for breast cancer.     

Dihydroartemisinin potentiates the anticancer effect of cisplatin via mTOR inhibition in cisplatin-resistant ovarian cancer cells: involvement of apoptosis and autophagy

Dihydroartemisinin (DHA) exhibits anticancer activity in tumor cells but its mechanism of action is unclear. Cisplatin (DDP) is currently the best known chemotherapeutic available for ovarian cancer. However, tumors return de novo with acquired resistance over time. Mammalian target of rapamycin (mTOR) is an important kinase that regulates cell apoptosis and autophagy, and its dysregulation has been observed in chemoresistant human cancers. Here, we show that compared with control ovarian cancer cells (SKOV3), mTOR phosphorylation was abnormally activated in cisplatin-resistant ovarian cancer cells (SKOV3/DDP) following cisplatin monotherapy. Treatment with cisplatin combined with DHA could enhance cisplatin-induced proliferation inhibition in SKOV3/DDP cells. This mechanism is at least partially due to DHA deactivation of mTOR kinase and promotion of apoptosis. Although autophagy was also induced by DHA, the reduced cell death was not found by suppressing autophagic flux by Bafilomycin A1 (BAF). Taken together, we conclude that inhibition of cisplatin-induced mTOR activation is one of the main mechanisms by which DHA dramatically promotes its anticancer effect in cisplatin-resistant ovarian cancer cells.     

In-situ monitoring of breast cancer cell (MCF-7) growth and quantification of the cytotoxicity of anticancer drugs fluorouracil and cisplatin

A wireless sensing device was developed for the in-situ monitoring of the growth of human breast cancer cells (MCF-7) and evaluation of the cytotoxicity of the anticancer drugs fluorouracil and cisplatin. The sensor is fabricated by coating a magnetoelastic ribbon-like sensor with a layer of polyurethane that protects the iron-rich sensor from oxidation and provides a cell-compatible surface. In response to a time-varying magnetic field, the magnetoelastic sensor longitudinally vibrates, emitting magnetic flux that can be remotely detected by a pick-up coil. No physical connections between the sensor and the detection system are required. The wireless property facilitates aseptic biological operation, especially in cell culture as illustrated in this work. The adhesion of cells on the sensor surface results in a decrease in the resonance amplitude, which is proportional to the cell concentration. A linear response was obtained in cell concentrations of 5x10(4) to 1x10(6)cellsml(-1), with a detection limit of 1.2x10(4)cellsml(-1). The adhesion strength of cells on the sensor is qualitatively evaluated by increasing the amplitude of the magnetic excitation field. And the cytotoxicity of the anticancer drugs fluorouracil and cisplatin is evaluated by the magnetoelastic biosensor. The cytostatic curve is related with the quantity of cytostatic drug. The lethal concentration (LC50) for cells incubated in the presence of drugs for 20h is calculated to be 19.9muM for fluorouracil and 13.1muM for cisplatin.     

Changes in plasma membrane fluidity of immortal rodent cells induced by anticancer drugs doxorubicin, aclarubicin and mitoxantrone

The aim of this study was to examine the effect of three structurally different anticancer drugs-the pro-oxidative anthracyclines doxorubicin (DOX) and aclarubicin (ACL), and antioxidative anthraquinone mitoxantrone (MTX) on the fluidity of plasma membrane of immortalized rodent fibroblasts using fluorescence spectroscopy and electron spin resonance (ESR) techniques. Two kinds of fluorescent probes (TMA-DPH and 12-AS) and spin labels (5-DS and methyl-12-DS) were used to monitor fluidity in the hydrophobic core and in the polar headgroup region of the lipid bilayer. Immortalized hamster B14 and NIH 3T3 mouse fibroblasts were exposed to DOX, ACL and MTX. We demonstrate that these drugs influence predominantly the hydrophobic core of the lipid bilayer, inducing significant decrease in its fluidity at low concentrations (2-5 microM). A decreased membrane fluidity at the surface of the lipid bilayer was observed only at a higher concentration (20 microM) of the drugs, which indicates that DOX, ACL and MTX intercalate mainly into the hydrophobic core of the membrane, thereby perturbing its structure.     

Inhibition of PKM2 sensitizes triple-negative breast cancer cells to doxorubicin

Cancer cells alter regular metabolic pathways in order to sustain rapid proliferation. One example of metabolic remodeling in cancerous tissue is the upregulation of pyruvate kinase isoenzyme M2 (PKM2), which is involved in aerobic glycolysis. Indeed, PKM2 has previously been identified as a tumor biomarker and as a potential target for cancer therapy. Here, we examined the effects of combined treatment with doxorubicin and anti-PKM2 small interfering RNA (siRNA) on triple-negative breast cancer (TNBC). The suppression of PKM2 resulted in changes in glucose metabolism, leading to decreased synthesis of adenosine triphosphate (ATP). Reduced levels of ATP resulted in the intracellular accumulation of doxorubicin, consequently enhancing the therapeutic efficacy of this drug in several triple-negative breast cancer cell lines. Furthermore, the combined effect of PKM2 siRNA and doxorubicin was evaluated in an in vivo MDA-MB-231 orthotopic breast cancer model. The siRNA was systemically administered through a polyethylenimine (PEI)-based delivery system that has been extensively used. We demonstrate that the combination treatment showed superior anticancer efficacy as compared to doxorubicin alone. These findings suggest that targeting PKM2 can increase the efficacy of chemotherapy, potentially providing a new approach for improving the outcome of chemotherapy in patients with TNBC.     

Synergistic action of taxol with tiazofurin and methotrexate in human breast cancer cells: Schedule-dependence

Taxol (paclitaxel, (NSC 125973)) is an active agent in the treatment of metastatic carcinoma of the breast; however, positive responses were observed in only about 60% of cases. Therefore, drug combinations which might improve the effectiveness are required. Since tiazofurin (2-β-D-ribofuranosylthiazole-4-carboxamide, NSC 286193), methotrexate (MTX) and taxol exert their anticancer action in different phases of the cell cycle and have different biochemical targets, we tested the hypothesis that tiazofurin and methotrexate might be synergistic with taxol. MDA-MB-435 human breast cancer cells were grown in monolayer in flasks. In the growth inhibition assay for tiazofurin, methotrexate and taxol the IC₅₀s were 12.5, 0.5 and 0.016 μM, respectively, and in the clonogenic assay 4.5, 0.065 and 0.004 μM. When taxol was given 6 hr before tiazofurin, antagonism was observed and summation was seen when drugs were given simultaneously. Synergism was obtained in both growth inhibitory and clonogenic assays when tiazofurin was followed 12 hr later by taxol. Methotrexate and taxol had an antagonistic effect when they were added simultaneously or when taxol was given 6 hr before methotrexate; summation was observed when taxol was followed 12 hr later by methotrexate. Synergistic action was obtained in the clonogenic assay when methotrexate was followed 12 hr later by taxol. The protocols yielding synergism should be of value in the design of taxol-based clinical trials for breast cancer.