Rapamycin and WYE-354 suppress human gallbladder cancer xenografts in mice

Gallbladder cancer (GBC) is a highly malignant tumor characterized by a poor response to chemotherapy and radiotherapy. We evaluated the in vitro and in vivo antitumor efficacy of mTOR inhibitors, rapamycin and WYE-354. In vitro assays showed WYE-354 significantly reduced cell viability, migration and invasion and phospho-P70S6K expression in GBC cells. Mice harboring subcutaneous gallbladder tumors, treated with WYE-354 or rapamycin, exhibited a significant reduction in tumor mass. A short-term treatment with a higher dose of WYE-354 decreased the tumor size by 68.6% and 52.4%, in mice harboring G-415 or TGBC-2TKB tumors, respectively, compared to the control group. By contrast, treatment with a prolonged-low-dose regime of rapamycin almost abrogated tumor growth, exhibiting 92.7% and 97.1% reduction in tumor size, respectively, compared to control mice. These results were accompanied by a greater decrease in the phosphorylation status of P70S6K and a lower cell proliferation Ki67 index, compared to WYE-354 treated mice, suggesting a more effective mTOR pathway inhibition. These findings provide a proof of concept for the use of rapamycin or WYE-354 as potentially good candidates to be studied in clinical trials in GBC patients.     

Autophagyinhibition by chloroquine sensitizes HT-29 colorectal cancer cells to concurrent chemoradiation Schonewolf CA,Mehta M,Schiff D,Wu H,Haffty BG,Karantza V,Jabbour SK简

AIM: To investigate whether the inhibition of autophagy by chloroquine (CQ) sensitizes rectal tumors to radiation therapy (RT) or concurrent chemoradiation (chemoRT).METHODS: In vitro, HCT-116 and HT-29 colorectal cancer (CRC) cell lines were treated as following: (1) PBS; (2) CQ; (3) 5-fluorouracil (5-FU); (4) RT; (5) CQ and RT; (6) 5-FU and RT; (7) CQ and 5-FU; and (8) 5-FU and CQ and RT. Each group was then exposed to various doses of radiation (0-8 Gy) depending on the experiment. Cell viability and proliferative capacity were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and clonogenic assays. Clonogenic survival curves were constructed and compared across treatment groups. Autophagy status was determined by assessing the LC3-II to LC3-I ratio on western blot analysis, autophagosome formation on electron microscopy and identification of a perinuclear punctate pattern with GFP-labeled LC3 on fluorescence microscopy. Cell cycle arrest and cell death were evaluated by FACS and Annexin V analysis. All experiments were performed in triplicate and statistical analysis was performed by the student’s t test to compare means between treatment groups.RESULTS: RT (2-8 Gy) induced autophagy in HCT-116 and HT-29 CRC cell lines at 4 and 6 h post-radiation, respectively, as measured by increasing LC3-II to LC3-I ratio on western blot. Additionally, electron microscopy demonstrated autophagy induction in HT-29 cells 24 h following irradiation at a dose of 8 Gy. Drug treatment with 5-FU (25 μmol/L) induced autophagy and the combination of 5-FU and RT demonstrated synergism in autophagy induction. CQ (10 μmol/L) alone and in combination with RT effectively inhibited autophagy and sensitized both HCT-116 and HT-29 cells to treatment with radiation (8 Gy; P < 0.001 and 0.00001, respectively). Significant decrease in clonogenic survival was seen only in the HT-29 cell line, when CQ was combined with RT at doses of 2 and 8 Gy (P < 0.5 and P = 0.05, respectively). There were no differences in cell cycle progression or Annexin V staining upon CQ addition to RT.CONCLUSION: Autophagy inhibition by CQ increases CRC cell sensitivity to concurrent treatment with 5-FU and RT in vitro, suggesting that addition of CQ to chemoRT improves CRC treatment response.     

Loss of XIAP sensitizes rosiglitazone-induced growth inhibition of colon cancer in vivo

Ligands for peroxisome proliferator-activated receptor gamma (PPAR gamma) possess anticancer properties. However, the efficacy of PPAR gamma ligands varies in different cancers. In colon cancer, the role of PPAR gamma and its ligands is controversial. We recently showed that downregulation of X-linked inhibitor of apoptosis protein (XIAP) could sensitize colon cancer cells to troglitazone, and 15-deoxy-D12,14-prostaglandin J2 (15-PGJ2) induced cell killing. In our study, we aimed to examine whether rosiglitazone, another more clinically relevant PPAR gamma ligand, has any synergistic anticancer effect with XIAP downregulation in colon cancer. Human colon cancer cell lines HCT116-XIAP(+/+) cells and HCT116-XIAP(-/-) cells were treated with various concentrations of rosiglitazone. The effects of rosiglitazone on cell proliferation, apoptosis and growth of xenograft colon cancers were studied. Rosiglitazone barely suppressed the growth and only very weakly induced apoptosis in HCT116 cells in vitro. Loss of XIAP did not sensitize HCT116 cells to rosiglitazone-induced growth inhibition or apoptosis. In vivo studies revealed that rosiglitazone strongly suppressed the growth of xenograft colon cancer, especially tumors derived from HCT116-XIAP(-/-) cells. The rosiglitazone-treated tumor had reduced expression of ki-67 and lowered mitotic rate. Downregulation of XIAP was associated with an impaired activation of PPAR gamma by its ligand. Rosiglitazone induced marked upregulation of PTEN in HCT116-XIAP(-/-) cells, as well as in xenograft tumors derived from HCT116-XIAP(-/-) cells. We concluded that rosiglitazone significantly suppresses the growth of xenograft colon cancer, and downregulation of XIAP sensitizes the xenograft tumors to rosiglitazone-induced tumor suppression in vivo via upregulation of PTEN.     

8-Cl-adenosine-induced inhibition of colorectal cancer growth in vitro and in vivo

The cAMP analogue 8-Cl-cAMP induces apoptosis and inhibits proliferation of a wide variety of malignancies in vitro and in vivo with relatively little toxicity. The antitumor effects of this compound are thought to involve its ability to modulate type I protein kinase A (PKAI). However, a nontoxic metabolite of 8-Cl-cAMP, 8-Cl-adenosine, with no known activity against PKAI, exerts growth inhibitory effects in breast, ovary, pancreas, and colorectal cancer cells in vitro and accumulates in xenografted tumors after 8-Cl-cAMP treatment in vivo. To characterize further the antitumor effects of 8-Cl-adenosine in colorectal cancer, we examined its effects on cell growth in vitro (cell number, ³H-thymidine incorporation, and soft agar colony formation) using the isogenically matched colorectal cancer cell lines HCT116, HCT116-E6 (p53-depleted), and 80S14 (p21^WAF1/Cip1-null). 8-Cl-adenosine inhibited cell growth by 89%, 74%, and 79%, respectively in HCT116, HCT116-E6, and 80S14 cells after a 72-hour exposure. Growth inhibition coincided with DNA endoreduplication and subsequent apoptosis. Furthermore, nontoxic doses of 8-Cl-adenosine administered i.p. twice weekly for 4 weeks to athymic mice suppressed growth of HCT116-derived xenografts by 50%. These results show that 8-Cl-adenosine exerts antitumor activity against colorectal cancer independent of p53 and p21^WAF1/Cip1.     

Perifosine sensitizes curcumin-induced anti-colorectal cancer effects by targeting multiple signaling pathways both in vivo and in vitro

Our study shows that coadministration of curcumin and an orally bioactive alkylphospholipid perifosine results in a significant increase in colorectal cancer cell apoptosis and a marked inhibition of cell growth both in vitro and in vivo. This novel combinatorial regimen leads to changes of multiple cell signaling pathways including inactivation of Akt and nuclear factor-κB as well as activation of c-Jun N-terminal kinases and endoplasmic reticulum stress. Further, perifosine and curcumin synergistically increase intracellular level of reactive oxygen species and ceramide, and downregulate the expression of cyclin D1 and Bcl-2 in colorectal cancer cells. These changes at molecular level together account for the cancer cell apoptosis and growth inhibition. We conclude that perifosine sensitizes colorectal cancer cells to curcumin by modulating multiple signaling pathways. Adding perifosine with curcumin may represent an effective therapy regimen against colorectal cancers, and possible other aggressive tumors.     

Autophagy inhibition promotes paclitaxel-induced apoptosis in cancer cells

Paclitaxel has been demonstrated to be an effective mitotic inhibitor and apoptosis inducer to treat aggressive malignancies. In this paper, we have provided a line of evidence that promotion of apoptotic cell death by paclitaxel was accompanied with induction of autophagy in A549 cells. Paclitaxel treatment could lead to the formation of acidic vesicular organelles (AVOs), the induction of Atg5, Beclin 1 and microtubule-associated protein 1 light chain 3 (LC3) expressions, and the increase of punctate fluorescent signals in A549 cells pre-transfected with green fluorescent protein (GFP)-tagged LC3. Interestingly, paclitaxel-mediated apoptotic cell death was further potentiated by pretreatment with autophagy inhibitor 3-methyladenine (3-MA) or small interfering RNA against the autophagic gene beclin1. These findings suggest that paclitaxel-elicited autophagic response plays a protective role that impedes the eventual cell death, and inhibition of autophagy could be an adjunctive strategy for enhancing chemotherapeutic effect of paclitaxel as an antitumor agent.     

Mortalin sensitizes human cancer cells to MKT-077-induced senescence

Mortalin is a chaperone protein that functions in many cellular processes such as mitochondrial biogenesis, intracellular trafficking, cell proliferation and signaling. Its upregulation in many human cancers makes it a candidate target for therapeutic intervention by small molecule drugs. In continuation to our earlier studies showing mortalin as a cellular target of MKT-077, a mitochondrion-seeking delocalized cationic dye that causes selective death of cancer cells, in this work, we report that MKT-077 binds to the nucleotide-binding domain of mortalin, causes tertiary structural changes in the protein, inactivates its chaperone function, and induces senescence in human tumor cell lines. Interestingly, in tumor cells with elevated level of mortalin expression, fairly low drug doses were sufficient to induce senescence. Guided by molecular screening for mortalin in tumor cells, our results led to the idea that working at low doses of the drug could be an alternative senescence-inducing cancer therapeutic strategy that could, in theory, avoid renal toxicities responsible for the abortion of MKT-077 clinical trials. Our work may likely translate to a re-appraisal of the therapeutic benefits of low doses of several classes of anti-tumor drugs, even of those that had been discontinued due to adverse effects.     

Sphingosine kinase-1 inhibition sensitizes curcumin-induced growth inhibition and apoptosis in ovarian cancer cells

Recent published studies suggest that increasing levels of ceramides enhance the chemo-sensitivity of curcumin. Using in vitro approaches, we analyzed the impact of sphingosine kinase-1 (SphK-1) inhibition on ceramide production, and evaluated SphK1 inhibitor II (SKI-II) as a potential curcumin chemo-sensitizer in ovarian cancer cells. We found that SphK1 is overexpressed in ovarian cancer patients' tumor tissues and in cultured ovarian cancer cell lines. Inhibition of SphK1 by SKI-II or by RNA interference (RNAi) knockdown dramatically enhanced curcumin-induced apoptosis and growth inhibition in ovarian cancer cells. SKI-II facilitated curcumin-induced ceramide production, p38 activation and Akt inhibition. Inhibition of p38 by the pharmacological inhibitor (SB 203580), a dominant-negative expression vector, or by RNAi diminished curcumin and SKI-II co-administration-induced ovarian cancer cell apoptosis. In addition, restoring Akt activation introducing a constitutively active Akt, or inhibiting ceramide production by fumonisin B1 also inhibited the curcumin plus SKI-II co-administration-induced in vitro anti-ovarian cancer effect, suggesting that ceramide accumulation, p38 activation and Akt inhibition are downstream effectors. Our findings suggest that low, well-tolerated doses of SKI-II may offer significant improvement to the clinical curcumin treatment of ovarian cancer.     

羟基磷灰石纳米粒子抑制胃癌细胞生长的体内外实验研究

目的:观察羟基磷灰石纳米粒子(Hydroxyapatite nanoparticles,Nano-HAP)对胃癌细胞系SGC-7901、BGC-823、MKN-28体外生长的影响及其对SGC-7901细胞皮下移植瘤裸鼠的抗瘤作用和药物毒性.方法:以不同浓度的Nano-HAP分别作用三种胃癌细胞48小时,MTT法检测其对胃癌细胞增殖的影响;以细胞划痕实验、黏附测定观察Nano-HAP对胃癌细胞侵袭力的影响;建立SGC-7901细胞皮下移植瘤裸鼠模型30只,随机分为对照组、Nano-HAP组和5-Fu组,观察每组移植瘤生长情况.结果:Nano-HAP可明显抑制胃癌细胞的增殖和生长,且呈剂量效应关系,并能降低胃癌细胞的体外侵袭和运动能力 (P＜0.05);同时可显著抑制SGC-7901细胞皮下移植瘤的生长,Nano-HAP组肿瘤体积明显小于对照组(P＜0.05),肿瘤生长抑制率达47.96%;5-Fu组抑瘤率达54.30%,但表现出明显不良反应.结论:Nano-HAP在体外和体内均可显著抑制胃癌细胞生长,并降低胃癌细胞体外侵袭和运动能力.     

羟基磷灰石纳米粒子抑制胃癌细胞生长的体内外实验研究

目的：观察羟基磷灰石纳米粒子（Hydroxyapatite nanoparticles,Nano—HAP）对胃癌细胞系SGC-7901、BGC-823、MKN-28体外生长的影响及其对SGC-7901细胞皮下移植瘤裸鼠的抗瘤作用和药物毒性。方法：以不同浓度的Nano—HAP分别作用三种胃癌细胞48小时,MTT法检测其对胃癌细胞增殖的影响;以细胞划痕实验、黏附测定观察Nano—HAP对胃癌细胞侵袭力的影响;建立SGC-7901细胞皮下移植瘤裸鼠模型30只,随机分为对照组、Nano—HAP组和5-Fu组,观察每组移植瘤生长情况。结果：Nano—HAP可明显抑制胃癌细胞的增殖和生长,且呈剂量效应关系,并能降低胃癌细胞的体外侵袭和运动能力（P〈0．05）;同时可显著抑制SGC-7901细胞皮下移植瘤的生长,Nano—HAP组肿瘤体积明显小于对照组（P〈0．05）,肿瘤生长抑制率达47．96％;5-Fu组抑瘤率达54．30％,但表现出明显不良反应。结论：Nano—HAP在体外和体内均可显著抑制胃癌细胞生长,并降低胃癌细胞体外侵袭和运动能力。     

Macroautophagy inhibition sensitizes tamoxifen-resistant breast cancer cells and enhances mitochondrial depolarization

Macroautophagy (autophagy), a process for lysosomal degradation of organelles and long-lived proteins, has been linked to various pathologies including cancer and to the cellular response to anticancer therapies. In the human estrogen receptor positive MCF7 breast adenocarcinoma cell line, treatment with the endocrine therapeutic tamoxifen was shown previously to induce cell cycle arrest, cell death, and autophagy. To investigate specifically the role of autophagy in tamoxifen treated breast cancer cell lines, we used a siRNA approach, targeting three different autophagy genes, Atg5, Beclin-1, and Atg7. We found that knockdown of autophagy, in combination with tamoxifen in MCF7 cells, results in decreased cell viability concomitant with increased mitochondrial-mediated apoptosis. The combination of autophagy knockdown and tamoxifen treatment similarly resulted in reduced cell viability in the breast cancer cell lines, estrogen receptor positive T-47D and tamoxifen-resistant MCF7-HER2. Together, these results indicate that autophagy has a primary pro-survival role following tamoxifen treatment, and suggest that autophagy knockdown may be useful in a combination therapy setting to sensitize breast cancer cells, including tamoxifen-resistant breast cancer cells, to tamoxifen therapy. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

GDC-0941 sensitizes breast cancer to ABT-737 in vitro and in vivo through promoting the degradation of Mcl-1

The present study showed that GDC-0941 potently sensitized breast cancer to ABT-737 in vitro and in vivo. ABT-737 exhibited limited lethality in breast cancer cells; however, when combined with GDC-0941, it displayed strong synergistic cytotoxicity and enhanced caspase-mediated apoptosis. GDC-0941 promoted proteasomal degradation of Mcl-1, of which the overexpression has been validated to confer ABT-737 resistance, thereby enhanced the anticancer efficacy of ABT-737. Furthermore, the combination of GDC-0941 and ABT-737 exerted increased anti-tumor efficacy on MDA-MB-231 xenograft models. Overall, our data described unprecedentedly the promising therapeutic potential and underlying mechanisms of combining GDC-0941 with ABT-737 in treating breast cancer.     

Shikonin exerts antitumor activity via proteasome inhibition and cell death induction in vitro and in vivo

Dysregulation of the ubiquitin‐proteasome pathway plays an essential role in tumor growth and development. Shikonin, a natural naphthoquinone isolated from the traditional Chinese medicine Zi Cao (gromwell), has been reported to possess tumor cell‐killing activity, and results from a clinical study using a shikonin‐containing mixture demonstrated its safety and efficacy for the treatment of late‐stage lung cancer. In this study, we reported that shikonin is an inhibitor of tumor proteasome activity in vitro and in vivo. Our computational modeling predicts that the carbonyl carbons C₁ and C₄ of shikonin potentially interact with the catalytic site of β5 chymotryptic subunit of the proteasome. Indeed, shikonin potently inhibits the chymotrypsin‐like activity of purified 20S proteasome (IC₅₀ 12.5 μmol/L) and tumor cellular 26S proteasome (IC₅₀ between 2–16 μmol/L). Inhibition of the proteasome by shikonin in murine hepatoma H22, leukemia P388 and human prostate cancer PC‐3 cultures resulted in accumulation of ubiquitinated proteins and several proteasome target proapoptotic proteins (IκB‐α, Bax and p27), followed by induction of cell death. Shikonin treatment resulted in tumor growth inhibition in both H22 allografts and PC‐3 xenografts, associated with suppression of the proteasomal activity and induction of cell death in vivo. Finally, shikonin treatment significantly prolonged the survival period of mice bearing P388 leukemia. Our results indicate that the tumor proteasome is one of the cellular targets of shikonin and inhibition of the proteasome activity by shikonin contributes to its antitumor property. © 2008 Wiley‐Liss, Inc.     

MiR-1204 sensitizes nasopharyngeal carcinoma cells to paclitaxel both in vitro and in vivo

Nasopharyngeal carcinoma (NPC) is an endemic tumor with a relatively high incidence in Southern China and Southeast Asia. Paclitaxel combination chemotherapy has been used for treatment of advanced NPC. However, treatment failure often occurs due to development of acquired paclitaxel resistance. In this study, we first established a paclitaxel-resistant CNE-1/Taxol, HNE-2/Taxol and 5–8F/Taxol cell sublines by treating the parental CNE-1, HNE-2 and 5–8F cells with increasing doses of paclitaxel for about 5 months, respectively. Then, microRNA arrays were used to screen differentially expressed miRNAs between the CNE-1/Taxol cells and the parental CNE-1 cells. We found 13 differentially expressed miRNAs, of which miR-1204 was significantly downregulated in the paclitaxel-resistant CNE-1/Taxol cells. We restored miR-1204 expression in the CNE-1/Taxol, HNE-2/Taxol and 5–8F/Taxol cells and found that restoration of miR-1204 re-sensitized the paclitaxel-resistant CNE-1/Taxol, HNE-2/Taxol and 5–8F/Taxol cells to paclitaxel both in vitro. Finally, we demonstrated that restoration of miR-1204 in significantly inhibits tumor growth in vivo. Thus, our study provides important information for the development of targeted gene therapy for reversing paclitaxel resistance in NPC.     

FANCD2 depletion sensitizes cancer cells repopulation ability in vitro

Inactivation of Fanconi anemia/BRCA pathway in some cancers causes increased sensitivity to various drugs used for chemo-therapy. Several approaches have been suggested to artificially disrupt this pathway for better treatment. In our study, we have utilized RNA interference technique to knock-down the expression of FANCD2 and sensitize cancer cells undergoing treatment with DNA damaging agents. For this purpose, we transiently depleted FANCD2 by siRNA in a number of breast, bladder, or liver cancer cell lines and screened for mitomycin C or gamma-irradiation sensitivity changes. We could show that knocking-down FANCD2 gene expression increases sensitivity of cancer cells to mitomycin C and to less extent to gamma-rays. Importantly, this effect strongly correlates to repopulation ability of cancer cells and those cell lines with significant FANCD2 depletion revealed decreased recurrence capacity. In summary, the results we presented show proof of principle that opens new possibilities for further preclinical trials.