Carcinoids are neuroendocrine malignancies characterized by their over production of various bioactive hormones that lead to the carcinoid syndrome. We have previously shown that AKT serves as a key regulator of growth and phenotypic expression of tumor markers in carcinoids by genetic depletion of AKT expression. However, no small molecule inhibitor of AKT kinase activity has been developed until recently. MK-2206, a novel allosteric inhibitor of AKT, is currently undergoing clinical trials for treatment of solid tumors. In this study, we explored the effect of MK-2206 on carcinoid cell proliferation and bioactive hormone production in vitro in two carcinoid cell lines-pancreatic carcinoid BON and bronchopulmonary H727. Treatment with MK-2206 effectively suppressed AKT phosphorylation at serine 473 and significantly reduced cell proliferation in a dose dependent manner. Most importantly, MK-2206 treatment resulted in a significant reduction of ASCL1, CgA, and NSE expression, collectively recognized as markers of neuroendocrine tumor malignancy. Furthermore, MK-2206 treated cells exhibited an increase in levels of cleaved PARP and cleaved caspase-3, with a concomitant reduction in levels of Mcl-1 and XIAP, suggesting that the anti-proliferative effect of MK-2206 occurs through the induction of apoptosis. In conclusion, MK-2206 alters neuroendocrine phenotype and suppresses carcinoid tumor growth, suggesting that this drug may be beneficial for patients with carcinoid syndrome. These studies merit further clinical investigation.
carcinoids; Akt pathway; chromogranin A; neuroendocrine markers; ASCL1
Large (>6 µm) rigid microparticles (MPs) become passively entrapped within the lungs following intravenous injection making them an attractive and highly efficient alternative to inhalation for pulmonary delivery. In the current studies, PEGylated 6 μm polystyrene MPs with multiple copies of the norvaline (Nva) α-amino acid prodrug of camptothecin (CPT) were prepared. Surface morphology was characterized using a scanning electron microscope (SEM). CPT was released from the CPT-Nva-MPs over 24 hours in rat plasma at 37°C. In vivo CPT plasma concentrations were low (~1 ng/mL or less) and constant over a period of 4 days after a single intravenous injection of CPT-Nva-MPs as compared to high but short-lived systemic exposures after an IV injection of free CPT. This suggests that sustained local CPT concentrations were achieved in the lung after administration of the MP delivery system. Anti-cancer efficacy was evaluated in an orthotopic lung cancer animal model and compared to a bolus injection of CPT. Animals receiving either free CPT (2 mg/kg) or CPT-Nva-MPs (0.22 mg/kg CPT, 100 mg/kg MPs) were found to have statistically significant smaller areas of lung cancer (P<0.05, P<0.01, respectively) than untreated animals. In addition, 40% of the animals receiving CPT-Nva-MPs were found to be free of cancer. The CPT dose using targeted MPs was ten fold lower than after IV injection of free CPT but was more effective in reducing the amount of cancerous areas. In conclusion, CPT-Nva-MPs were able to achieve effective local lung and low systemic CPT concentrations at a dose that was ten times lower than systemically administered CPT resulting in a significant improvement in anticancer efficacy in an orthotopic rat model of lung cancer.
Lung cancer; microparticles; passive pulmonary targeting; camptothecin
Epigenetic aberrations and a CpG island methylator phenotype are associated with poor outcome in children with neuroblastoma (NB). Previously, we demonstrated that valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, has antitumor effects in an NB xenograft model. However, the underlying antitumor molecular mechanisms are largely unknown. In this study, we investigated the role of HDAC in cell proliferation, cell cycle progression, gene expression patterns, and epigenome in neuroblastoma. Cell proliferation, cell cycle progression, caspase activity, RNA and protein expression, quantitative methylation, and global DNA methylation were examined in NBL-W-N and LA1-55n NB cell lines. Our studies demonstrated that Inhibition of HDAC decreased NB proliferation and induced G1 growth arrest. Expression patterns of cancer-related genes were modulated by VPA. THBS1, CASP8, SPARC, CDKN1A, HIC1, CDKN1B, and HIN1 expression was upregulated, and MYCN and TIG1 were downregulated. HDAC inhibition decreased methylation levels of THBS1 and RASSF1A promoters. Inhibition of HDAC increased acetylation of histone 4 and global DNA methylation levels. Our studies demonstrated that inhibition of HDAC blocked cell proliferation and cell cycle progression in relation to alteration of cancer related genes, increasing global DNA methylation and decreasing methylation of tumor suppressor genes. Further studies investigating the anti-tumor effects of VPA in NB are warranted.
Histone deacetylase; histone acetylation; cell proliferation; cell cycle; valproic acid; neuroblastoma; DNA methylation
Breast cancer mortality is primarily due to the occurrence of metastatic disease. We have identified a novel potential therapeutic agent derived from an edible root of the plant Colocasia esculenta, commonly known as taro, that has demonstrable activity in a preclinical model of metastatic breast cancer and that should have minimal toxicity. We have shown for the first time that a water-soluble extract of taro (TE) potently inhibits lung colonizing ability as well as spontaneous metastasis from mammary gland-implanted tumors, in a murine model of highly metastatic ER, PR and Her-2/neu negative breast cancer. TE modestly inhibits proliferation of some, but not all, breast and prostate cancer cell lines. Morphologic changes including cell rounding were observed. Tumor cell migration was completely blocked by TE. TE treatment also inhibited prostaglandin E2 (PGE2) synthesis and downregulated cyclooxygenase (COX) 1 and 2 mRNA expression. We purified the active compound(s) to near homogeneity with antimetastatic activity comparable to stock TE. The active compound with a native size of approximately 25 kD contains two fragments of nearly equal size. The N-terminal amino acid sequencing of both fragments reveals that the active compound is highly related to three taro proteins; 12 kD storage protein, tarin and lectin. All are similar in terms of amino acid sequence, post-translational processing and all contain a carbohydrate-binding domain. This is the first report describing a compound(s) derived from taro, that potently and specifically inhibits tumor metastasis.
Taro; Breast cancer; Antimetastatic activity; Tumor; Cancer therapy
Peptides are receiving increased attention as therapeutic agents, due to their high binding specificity and versatility to be modified as targeting or carrier molecules. Particularly, peptides with anti-angiogenic activity are of high interest due to their applicability to a wide range of cancers. In this study we investigate the biological activity of two novel antiangiogenic peptides in pre-clinical glioma models. One peptide SP2000 is derived from collagen IV and the other peptide SP3019 belongs to the CXC family. We previously characterized the capacity of SP2000 and SP3019 to inhibit multiple biological endpoints linked to angiogenesis in human endothelial cells in several assays. Here we report additional studies using endothelial cells and focus on the activity of these peptides against human glioma cell growth, migration and adhesion in vitro and growth as tumor xenografts in vivo. We found that SP2000 completely inhibits migration of the glioma cells at 50 μM and SP3019 produced 50% inhibition at 100 μM. Their relative anti-adhesion activities were similar with SP2000 and SP3019 generating 50% adhesion inhibition at 4.9 ± 0.82 μM and 21.3 ± 5.92 μM respectively. In vivo glioma growth inhibition was 63 % for SP2000 and 76% for SP3019 after 2 weeks of administration at daily doses of 10mg/kg and 20 mg/kg, respectively. The direct activity of these peptides against glioma cells in conjunction with their anti-angiogenic activities warrants their further development as either stand-alone agents or in combination with standard cytotoxic or emerging targeted therapies in malignant brain tumors.
Angiogenesis; cancer therapy; endothelial cell; glioblastoma; proliferation; migration; adhesion
An in vitro 72 hour assay using median effect analysis and curve shift analysis was employed to evaluate the utility of potentially clinically useful combinations of agents for synergism or antagonism. Six human breast cancer cell lines both receptor rich and receptor poor were studied. Panobinostat (LBH-589), a pan histone deacetylase inhibitor with a multitude of biological effects, exhibits time dependent synergistic effects in breast cancer cell lines with docetaxel, doxorubicin, or gemcitabine in clinically relevant concentrations. Survivin expression was markedly down regulated in the presence of panobinostat with gemcitabine. Bortezomib, a proteasome inhibitor, markedly enhanced the cytotoxic effects of panobinostat combined with gemcitabine. Panobinostat did not demonstrate universal enhancement of cytotoxic drugs, and therefore synergy was dependent upon the second agent selected. No synergy was noted with anti Her2 agents in Her2 over expressing cell lines. Metformin combined with panobinostat demonstrated no synergy in this test system. These effects were confirmed by apoptosis assay and caspase-3 production. A positive drug interaction was identified. The triplet of panobinostat with either doxorubicin /carboplatin or gemcitabine / carboplatin was especially potent in all cell lines. As all these agents are clinically available, further studies of the potent combinations are warranted.
synergism; breast cancer; therapy; survivin; combination; in vitro
The objective of this study was to evaluate extracelluar matrix metalloproteinase (EMMPRIN) as a novel target in orthotopic pancreatic-cancer murine models. MIA PaCa-2 human pancreatic tumor cells were implanted in groups 1 and 3-7, while MIA PaCa-2 EMMPRIN knockdown cells were implanted in group 2. Dosing with anti-EMMPRIN antibody started immediately after implantation for groups 1-3 (residual tumor model) and at 21 days after cell implantation for groups 4-7 (established tumor model). Groups 3, 5, and 7 were treated with anti-EMMRPIN antibody (0.2-1.0 mg) twice weekly for 2-3 weeks, while the other groups served as the control. In residual tumor model, tumor growth of anti-EMMPRIN treated group was successfully arrested for 21 days (15±4 mm3), significantly lower than that of EMMPRIN knockdown group (80±15 mm3; p=0.001) or control group (240±41 mm3; p<0.001). In established tumor model, anti-EMMPRIN therapy lowered tumor-volume increase about 40% compared with control regardless of dose amount. Ki67-expressed cell densities of group 5 was 939±150 mm−2, significantly lower than that of group 4 (1709±145 mm−2; p=0.006). Microvessel density of group 5 (30±6 mm−2) was also significantly lower than that of group 4 (53±5 mm−2; p=0.014), while the microvessel size of group 5 (191±22 μm2) was significantly larger than that of group 4 (113±26 μm2; p=0.049). These data show the high potential of anti-EMMPRIN therapy for pancreatic cancer, and support its clinical translation.
EMMPRIN; Targeted therapy; Pancreatic cancer
Ovarian cancer is the most lethal gynecological malignancy among US women. Paclitaxel/carboplatin is the current drug therapy used to treat ovarian cancer, but most women develop drug resistance and recurrence of the disease, necessitating alternative strategies for treatment. A possible molecular target for cancer therapy is glycogen synthase kinase 3β (GSK3β), a downstream kinase in the Wnt signaling pathway that is overexpressed in serous ovarian cancer. Novel maleimide-based GSK3β inhibitors (GSK3βi) were synthesized, selected, and tested in vitro using SKOV3 and OVCA432 serous ovarian cancer cell lines. From a panel of 10 inhibitors, the GSK3βi 9ING41 was found to be the most effective in vitro. 9ING41 induced apoptosis as indicated by 4′6-diamidino-2-phenylindole (DAPI) positive nuclear condensation, poly (ADP-ribose) polymerase (PARP) cleavage, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. The mechanism for apoptosis was through caspase-3 cleavage. GSK3βi upregulated phosphorylation of the inhibitory serine residue of GSK3β in the OVCA432 and SKOV3 cell lines as well as inhibited phosphorylation of the downstream target glycogen synthase. An in vivo xenograft study using SKOV3 cells demonstrated that tumor progression was hindered by 9ING41 in vivo. The maximum tolerated dose for 9ING41 was greater than 500 mg/kg in rats. Pharmacokinetic analysis showed 9ING41 to have a bioavailability of 4.5% and was well distributed in tissues. Therefore, GSK3β inhibitors alone or in combination with existing drugs may hinder growth of serous ovarian cancers.
Ovarian cancer; Wnt; GSK3beta; xenograft; drug discovery
Mutations/deletions of the tumor suppressor phosphatase and tensin homolog PTEN, results in PI3K/Akt pathway hyperactivation and potentially alters oncogenic responses to targeted receptor tyrosine kinase inhibitors. We previously showed that hepatocyte growth factor (HGF):c-Met pathway inhibition decreases tumor growth and oncogenic signaling responses in PTEN-null/Met+ gliomas. Here we utilize two tet-on PTENwt-inducible glioma cell lines and xenograft models to examine the influence of PTEN on oncogenic signaling responses to HGF:c-Met pathway inhibitors. Reconstitution of PTEN inhibited Akt by >80% and inhibited cell growth by ~70–75 % in both cell lines in vitro. C-Met inhibition alone inhibited in vitro cell growth by ~80–85 % and the magnitude of growth inhibition was not altered by combining PTEN reconstitution with c-Met inhibition. Combining PTEN reconstitution with Met inhibition arrested a higher percentage of cells in G1/G0 phase of the cell cycle when compared to either PTEN reconstitution or c-Met inhibition alone. Both PTEN reconstitution alone and inhibiting autocrine HGF:c-Met signaling alone, using anti-HGF mAb, robustly inhibited the growth of subcutaneous and intracranial glioma xenografts. Combining anti-HGF therapy with PTEN reconstitution did not significantly alter the magnitude of xenograft growth inhibition. Semi-quantitative immunohistopathological analyses revealed that the inhibition of glioma xenograft angiogenesis and cell proliferation by anti-HGF mAb was greatest in conjunction with PTEN reconstitution. In contrast, xenograft cell apoptosis was greatest in response to anti-HGF therapy alone and PTEN reconstitution abrogated the apoptotic response to anti-HGF therapy. These results provide new insights into how PTEN modulates glioma responses to the inhibition of HGF:c-Met signaling and possibly other receptor tyrosine kinase pathways.
hepatocyte growth factor; Akt; xenograft; apoptosis; angiogenesis
Gap junctions are intercellular channels connecting adjacent cells, allowing cells to transport small molecules. The loss of gap junctional intercellular communication (GJIC) is one of the important hallmarks of cancer. Restoration of GJIC is related to the reduction of tumorigenesis and increase in drug sensitivity. Previous reports have shown that PQ1, a quinoline derivative, increases GJIC in T47D breast cancer cells, and subsequently attenuates xenograft breast tumor growth. Combinational treatment of PQ1 and tamoxifen can lower the effective dose of tamoxifen in cancer cells. In this study, the effects of PQ1 were examined in normal C57BL/6J mice, evaluating the distribution, toxicity, and adverse effects. The distribution of PQ1 was quantified by high-performance liquid chromatography and mass spectrometry. The expressions of survivin, caspase-8, cleaved caspase-3, aryl hydrocarbon receptor (AhR), and gap junction protein, connexin 43 (Cx43), were assessed using western blot analysis. Our results showed that PQ1 was absorbed and distributed to vital organs within 1 h and the level of PQ1 decreased after 24 h. Furthermore, PQ1 increased the expression of survivin, but decreased the expression of caspase-8 and caspase-3 activity. Interestingly, the expression of AhR increased in the presence of PQ1, suggesting that PQ1 may be involved in the AhR-mediated response. Previously, PQ1 caused an increase in Cx43 expression in breast cancer cells; however, PQ1 induced a decrease in Cx43 in normal tissues. Hemotoxylin and eosin staining of the tissues showed no histological change between the treated and the untreated organs. Our studies indicate that the administration of PQ1 by an oral gavage can be achieved with low toxicity to normal vital organs.
adverse effect; anti-breast cancer agent; distribution; gap junction; PQ1; toxicity
Multiple molecularly targeted agents (MTAs) have been approved for the management of metastatic renal cell carcinoma(mRCC). Sunitinib and M-TOR inhibitors (temsirolimus, everolimus) are primarily metabolized in the liver, while the metabolism of bevacizumab is unclear. There are limited data on the toxicity profile and efficacy of these agents in patients with renal impairment(RI). This is clinically relevant especially since about one third of mRCC patients have renal dysfunction.
The primary objective was to assess the safety and efficacy of targeted agents in mRCC patients with RI. Medical records of patients with mRCC at Wayne State University started on sunitinib, temsirolimus, everolimus or bevacizumab were reviewed. Patients with a calculated creatinine clearance(CrCl) of ≤60ml/min were deemed to have RI. Data on safety and efficacy of MTA therapy were collected and analyzed with respect to renal function.
RI was observed in 33% of our mRCC patients. The incidence of toxicities, responses, time to progression(TTP), and overall survival(OS) were not significantly different in patients with RI compared to patients with normal renal function. Patients with RI had larger median increases in blood pressure with sunitinib and bevacizumab, increased incidence of thyroid dysfunction with sunitinib, and increased incidence of rash and dose interruptions with m-TOR inhibitors, than did patients with normal renal function.
RI was commonly observed in our mRCC patients. MTAs are well tolerated and efficacy appears to be maintained in patients with RI. Vigilant monitoring of hypertension would be recommended for pts receiving sunitinib and bevacizumab.
renal dysfunction; kidney cancer; sunitinib; temsirolimus; bevacizumab; everolimus
Head and neck squamous cell cancer (HNSCC) is the sixth most common cancer in the world. Despite advances in combined modality therapy, poor outcomes continue to be observed in the form of locoregional recurrence, metastasis, and development of second primary tumors. Because tumors vary in their molecular and genetic etiology and because often times there is already deregulation at the molecular level in otherwise histopathologically normal tissue, risk stratification using clinical and pathologic criteria alone has proved to be inadequate. In this article, the reader will gain an appreciation for the current advances in biomarker discovery via advanced technology and data interpretation in microarray analysis and proteomics. In addition, other molecular targets, aside from EGFR, are discussed in the context of their promising role in predicting recurrence, response to therapy, survival and overall prognosis.
Head and neck squamous cell carcinoma (HNSCC); biomarker; microarray; proteomics; epidermal growth factor receptor (EGFR)
The concept of immunotherapy as a treatment for cancer patients has been in existence for decades. However, more recent immune therapeutic approaches have involved targeting of tumor-specific antigens. While improvements have been made in using such immune stimulatory treatment strategies for a variety of solid cancers, the use of these strategies for patients with head and neck squamous cell carcinoma (HNSCC) is lagging behind. Immunotherapeutic approaches for HNSCC are particularly complicated by the profound immune suppression that is induced by HNSCC, which potentially lessens the effectiveness of immune stimulatory efforts. Trials involving patients with various solid cancers have shown the enhanced effectiveness of combining various immunotherapeutic approaches or combining immunotherapy with chemotherapy or radiation therapy. Treatment of HNSCC with such combination approaches has not been extensively investigated and has the added challenge of the need to overcome the HNSCC-induced immune suppression. This review focuses on clinical trials that have tested immunotherapeutic approaches for HNSCC patients and the challenges associated with such approaches. In addition, it will call attention to immunotherapeutic strategies that have been demonstrated as successful in the treatment of other solid cancers in order to identify potential strategies that may apply to the treatment of HNSCC.
head and neck cancer; HNSCC; immunosuppression; immunotherapy; suppressor cells; tumor antigens
Pancreatic ductal adenocarcinoma (PDAC) is among the leading causes of cancer deaths and is unresponsive to existing therapy. Smoking and alcohol-induced pancreatitis are among the risk factors for PDAC. We have previously reported that beta-adrenergic receptors (β-ARs) stimulate the proliferation and migration of human PDAC cells in vitro via cAMP-dependent signaling and that the nicotine-derived nitrosamine NNK activates this pathway directly in vitro while additionally stimulating the release of noradrenaline/adrenaline by binding to α7 nicotinic acetylcholine receptors in hamsters. In the current study, we have tested the hypothesis that the β-AR antagonist propranolol prevents the development of PDAC induced in hamsters with ethanol-induced pancreatitis by NNK. We found that propranolol had strong cancer preventive effects in this animal model. Western blots of pancreatic duct cells and PDAC cells harvested by laser capture microscopy showed significant upregulation of the α7nicotinic acetylcholine receptor (α7nAChR) associated with significant inductions of p-CREB, p-ERK1/2 and increases in EGF and VEGF in PDAC cells of hamsters not treated with propranolol. These effects were reversed by treatment with propranolol. Our data suggest that propranolol may prevent the development of PDAC by blocking cAMP-dependent intracellular signaling, cAMP-dependent release of EGF and PKA-dependent release of VEGF while additionally downregulating the α7nAChR via inhibition of cAMP-mediated subunit assembly. We conclude that increased cAMP signaling is an important factor that drives the development and progression of PDAC and that the inhibition of cAMP formation is a promising new target for the prevention and adjuvant therapy of PDAC.
Protopanaxadiol (PPD), an aglycon of ginseng saponins, has shown anticancer activity in previous studies. Here we report the semi-synthesis of 9 PPD derivatives with acetyl substitutions. Subsequently, the antiproliferative effects of these 9 analogs on different human cancer cell lines were investigated. Compounds 1 and 3 showed more significant and more potent antiproliferative activity compared to PPD and other derivatives. A flow cytometric assay indicated that Compounds 1 and 3 arrested cell cycle progression in the G1 phase and significantly induced apoptosis of cancer cells.
protopanaxadiol derivatives; semi-synthesis; apoptosis; cell cycle; colon cancer
Prostate cancer cells undergo neuroendocrine differentiation during androgen deprivation and secrete neuropeptides, hence activating androgen receptor-regulated genes. Src family protein kinases are involved in neuropeptide-induced prostate cancer growth and migration. A phase II trial of AZD0530, an oral Src-family kinase inhibitor, in patients with advanced castration resistant prostate cancer was conducted.
The primary endpoint was prostate cancer specific antigen (PSA) response rate, defined as a 30% or greater decrease. A two-stage Simon design was employed. Eligibility criteria included documentation of castration resistance (including anti-androgen withdrawal), adequate end-organ function and performance status, and no more than one prior taxane-based chemotherapy regimen. AZD0530 was given at 175 mg orally once daily continuously.
Rapid accrual led to 28 patients registering in the first stage. Median age was 67 years. Sixteen patients had performance status (PS) 0, 8 had PS 1, and 4 had PS 2. Nine patients (32%) had prior docetaxel-based chemotherapy. Five patients had transient PSA reductions not meeting PSA response criteria. Median progression-free survival time was 8 weeks. Treatment was generally well tolerated.
AZD0530, a potent oral src kinase inhibitor, is feasible and tolerable in this pre-treated patient population but possessed little clinical efficacy as monotherapy. Strong preclinical evidence warrants further investigation of AZD0530 in earlier stage prostate cancer or as combination therapy.
Src-inhibitor; prostate cancer; castration-resistant
The novel cytokine melanoma differentiation associated gene-7 (mda-7) was identified by subtractive hybridization in the mid-1990s as a protein whose expression increased during the induction of terminal differentiation, and that was either not expressed or was present at low levels in tumor cells compared to non-transformed cells. Based on conserved structure, chromosomal location and cytokine-like properties, MDA-7, has now been classified as a member of the expanding interleukin (IL)-10 gene family and designated as MDA-7/IL-24. Multiple studies have demonstrated that expression of MDA-7/IL-24 in a wide variety of tumor cell types, but not in corresponding equivalent non-transformed cells, causes their growth arrest and ultimately cell death. In addition, MDA-7/IL-24 has been noted to be a radiosensitizing cytokine, which in part is due to the generation of reactive oxygen species (ROS) and ceramide that cause endoplasmic reticulum stress. Phase I clinical trial data has shown that a recombinant adenovirus expressing MDA-7/IL-24 (Ad.mda-7 (INGN-241)) was safe and had measurable tumoricidal effects in over 40% of patients, which strongly argues that MDA-7/IL-24 may have significant therapeutic value. This review describes what is known about the impact of MDA-7/IL-24 on tumor cell biology and its potential therapeutic applications.
MDA-7: melanoma differentiation associated gene 7
Artemisinin is a plant derived anti-malarial drug that has relatively low toxicity in humans and is activated by heme and/or intracellular iron leading to intracellular free radical formation. Interestingly, artemisinin has displayed anti-cancer activity with artemisinin dimers being more potent than monomeric artemisinin. Intracellular iron uptake is regulated by the transferrin receptor (TfR), and the activity of artemisinin depends on the availability of iron. We examined the level of TfR in prostate cancer (PCa) tumor cells, synthesized two new artemisinin dimers, and evaluated the effect of dihydroartemisinin (DHA) and artemisinin dimers ON-2Py and 2Py on proliferation and apoptosis in PCa cells. TfR was expressed in the majority of PCa bone and soft tissue metastases, all twenty-four LuCaP PCa xenografts, and PCa cell lines. After treatment with DHA, ON-2Py, or 2Py all PCa cell lines displayed a dose dependent decrease in cell number. 2Py was the most effective at decreasing cell number. An increase in apoptotic events and growth arrest was observed in the C4-2 and LNCaP cell lines. Growth arrest was observed in PC-3 cells, but no significant change was observed in DU 145 cells. Treatment with 2Py resulted in a loss of the anti-apoptotic protein survivin in all four cell lines. 2Py treatment also decreased androgen receptor and PSA expression in C4-2 and LNCaP cells with a concomitant loss of cell cycle regulatory proteins Cyclin D1 and c-Myc. This study demonstrates the potential use of artemisinin derivatives as therapeutic candidates for PCa and warrants the initiation of pre-clinical studies.
Artemisinin; apoptosis; cell cycle; androgen receptor; prostate cancer; dimer
Treatment of cancer with tumor necrosis factor-α (TNFα) is hindered by resistance and toxicity. The Flexible Heteroarotinoid (Flex-Het), SHetA2, sensitizes resistant ovarian cancer cells to TNFα-induced extrinsic apoptosis, and also induces intrinsic apoptosis as a single agent. This study tested the hypothesis that nuclear factor kappa B (NF-κB) is involved in SHetA2-regulated intrinsic and extrinsic apoptosis. SHetA2 inhibited basal and TNFα- or hydrogen peroxide-induced NF-κB activity through counter-regulation of upstream kinase (IKK) activity, inhibitor protein (IκBα) phosphorylation, and p65 NF-κB subunit nuclear translocation, but independently of reactive oxygen species (ROS) generation. Ectopic over-expression of p65, or treatment with TNFα receptor 1 (TNFR1) siRNA or a caspase 8 inhibitor, each attenuated synergistic apoptosis by SHetA2 and TNFα, but did not affect intrinsic apoptosis caused by SHetA2. In conclusion, NF-κB repression is involved in SHetA2 circumvention of resistance to TNFα-induced extrinsic apoptosis, but not in SHetA2 induction of intrinsic apoptosis.
Apoptosis; TNF α Resistance; NF-κB; IKK repression; Ovarian Cancer
Pancreatic cancer is the fourth leading cause of cancer death in the United States. The prognosis of the disease is very negative since the cancer has usually metastasized by the time a patient manifests symptoms. Although combination therapy shows some promise, new drugs to treat the disease are needed. Given our interest in finding new therapies for pancreatic cancer, we sought to determine whether the known cytotoxic activity of the batzellines extended to pancreatic cancer cell lines. The batzellines are pyrroloiminoquinones alkaloids obtained from the deep water Caribbean sponge Batzella sp (family Esperiopsidae, order Poecilosclerida). We show here that batzellines exhibit selective cytotoxicity towards the pancreatic cancer cell lines AsPC-1, Panc-1, BxPC-3, and MIA PaCa2 compared to the normal African green monkey cell line Vero. The batzellines cause cytotoxicity by inducing cell cycle arrest that is mediated by their ability to intercalate into DNA and/or inhibit Topoisomerase II activity. The cytotoxic abilities of Isobatzellines A and C against pancreatic cancer cell lines, their low toxicity against normal cells and their reported ability to be synthesized makes them interesting compounds with potential chemotherapeutic effects that may merit further research.
Natural Products; Pancreatic Cancer; Drug Discovery; Mechanism of Action
Breast cancer is the second leading cause of cancer deaths among women in the US. Several treatment options exist, with different side effects. To alleviate the side effects several research groups have studied chemotherapeutic effects of plant compounds on cancer cells. These could be used as an alternative treatment option either alone or in combination with other chemotherapeutic drugs. The aim of the study was to evaluate the activity of a combination of perillyl alcohol (POH), methyl jasmonate (MJ) with cisplatin to define the most effective schedule and to investigate the mechanism of action in breast cancer cells. POH and MJ treatment (IC20 concentration) enhanced the cytotoxicity for subsequent exposure to cisplatin in MDA-MB-435 and MDA-MB-231 cells. Combination treatment of POH and MJ blocked cells at the G0/G1 phase of the cell cycle and the addition of cisplatin forced the cells to progress through the cell cycle and induced apoptosis. Apoptotic mechanistic studies indicated that POH and MJ treatment activated TNFR1 and this was further increased by the addition of cisplatin. It was also found that mitochondrial membrane potential decreased with POH and MJ treatment, this effect was further enhanced by cisplatin treatment. These findings contributed to a better understanding of molecular mechanism of apoptosis in combination treatment of POH, MJ and cisplatin. Results also demonstrated that combination treatment of three drugs is more effective than single drug or two drugs together.
Edotecarin (J-107088), a novel inhibitor of topoisomerase I has an additive effect on colon cell lines (HCT-116) when combined with 5-fluorouracil (5-FU). We conducted a phase I study to determine the maximum tolerated dose and recommended a phase II dose of edotecarin in combination with infusional 5-FU/leucovorin (LV) in patients with advanced solid tumors. Patients and cohorts of three to six patients were sequentially enrolled at progressively higher dose levels of edotecarin administered as a 1-h intravenous (IV) infusion every 2 weeks. The edotecarin starting dose was 6mg/m2, followed by 200mg/m2 LV IV infusion administered over 2 h, then 400mg/m2 bolus dose of 5-FU before the start of 2400mg/m2 5-FU continuous infusion for a further 46 h. Patients were evaluated for safety, pharmacokinetics, and tumor response according to the Response Evaluation Criteria in Solid Tumors criteria. Fourteen patients (10 male; four female) received a total of 90 cycles (range 3–18). Dose-limiting toxicities were observed in five of the 14 patients treated in the study. All dose-limiting toxicities were related to neutropenia. Only the 6 and 8mg/m2 edotecarin dose levels were explored; however, no maximum tolerated dose was declared. One confirmed complete response in a patient with hepatocellular carcinoma and seven stable disease responses were achieved in the 14 treated patients. Pharmacokinetic analysis showed that edotecarin achieved and maintained apparent steady-state plasma concentrations during the IV administration in both the cycles. The administration of edotecarin in combination with infusional 5-FU/LV once every 14 days, even without the 5-FU bolus, did not permit adequate time for recovery from neutropenia.
edotecarin; J-107088; maximum tolerated dose; pharmacokinetics; solid tumor; topoisomerase I inhibitor
Curcumin, a yellow pigment and the active component of turmeric, has been shown to protect against carcinogenesis and prevent tumor development in several types of cancer. However, its low bioavailability and potency prevent it from being effective in most chemotherapeutic applications. One potential means of circumventing this problem has been the creation of synthetic curcumin analogues. We tested the efficacy of two such analogues, known as FLLL11 and FLLL12, in human pancreatic cancer cell lines. We compared the impact of curcumin with FLLL11 and FLLL12 on cell viability in five different pancreatic cancer cell lines. Although all three compounds were capable of lowering viability in all cell lines tested, FLLL11 and FLLL12 (IC50 values between 0.28–3.2 and 0.91–3.43λμmol/l, respectively) were substantially more potent than curcumin (IC50 values between 8.67 and 20.35λμmol/l). In addition, FLLL11 and FLLL12 inhibited phosphorylation of signal transducer and activator of transcription 3 and AKT, two cell signaling pathways frequently found persistently active in many forms of cancer. Furthermore, FLLL11 and FLLL12 were found to be more effective than curcumin in inducing apoptosis as evidenced by increased cleavage of PARP and caspase-3 in pancreatic cancer cell lines. These results indicate that the curcumin analogues, FLLL11 and FLLL12, are more effective than curcumin in inhibiting cell viability and inducing apoptosis, and may have translational potential as chemopreventive or therapeutic agents for pancreatic cancer.
AKT; curcumin; pancreatic cancer; signal transducer and activator of transcription 3
Pentamidine is a small molecule inhibitor of the Ca2+ binding protein S100B and disrupts the S100B-p53 protein-protein interaction; this is thought to restore wild type p53 tumour suppressor function in melanoma. Additional anti-cancer effects may be the result of inhibition of PRL family phosphatases.
In this study we have used a standardised ATP Tumour Chemosensitivity Assay (ATP-TCA) to investigate the effect of pentamidine on cells derived from 18 skin melanoma samples, and 1 uveal melanoma sample. The cells were tested at six concentrations from which the IC50 and IC90 were calculated. To allow comparison between samples, an IndexSUM was calculated based on percentage tumour growth inhibition at each concentration.
Of the skin melanoma samples tested, 78% exhibited an IndexSUM<300 indicating strong inhibition. The median IndexSUM of 237 also indicates strong inhibition. The median IC90 was 79.5% of the test drug concentration (30.2 μM) consistent with a strong response at a clinically achievable drug concentration. The uveal melanoma sample exhibited and IndexSUM=333, indicating moderate inhibition, and 86% inhibition at test drug concentration (30.2 μM).
These results support the prospect of a therapeutic use for pentamidine in melanoma, and a phase II clinical trial is in progress.
Chemosensitivity; melanoma; pentamidine; ATP
Our earlier studies have shown the in vitro and in vivo targeting of a generation 5 (G5) dendrimer-based multifunctional conjugate that contained folic acid (FA) as the targeting agent and methotrexate (MTX) as the chemotherapeutic drug. To clinically apply the synthesized G5-FA-MTX nanotherapeutic, it is important that the anticancer conjugate elicits cytotoxicity specifically and consistently. Toward this objective, we evaluated the large-scale synthesis of a G5-FA-MTX conjugate (Lot # 123–34) for its cytotoxic potential and specificity in vitro and in vivo. The cytotoxicity and specificity were tested by using a coculture assay in which FA receptor-expressing and nonexpressing cells (KB and SK-BR-3 cells, respectively) were cultured together and preferential killing was examined. The in-vitro data were compared with the in-vivo data obtained from a heterogeneous xenograft tumor model. The animal model of the artificial heterogeneous xenograft tumor showed that the nanotherapeutic was preferentially cytotoxic to KB cells.
coculture assay; dendrimer; heterogeneous xenograft tumor model; methotrexate; neoplasm; targeted drug delivery