ABSTRACT
KRAS is activated by mutation in the vast majority of cases of pancreatic cancer; unfortunately, therapeutic attempts to inhibit KRAS directly have been unsuccessful. Our previous studies showed that inhibition of cyclin-dependent kinase 5 (CDK5) reduces pancreatic cancer growth and progression, through blockage of the centrally important RAL effector pathway, downstream of KRAS. In the current study, the therapeutic effects of combining the CDK inhibitor dinaciclib (SCH727965; MK-7965) with the pan-AKT inhibitor MK-2206 were evaluated using orthotopic and subcutaneous patient-derived human pancreatic cancer xenograft models. The combination of dinaciclib (20 mg/kg, i.p., three times a week) and MK-2206 (60 mg/kg, orally, three times a week) dramatically blocked tumor growth and metastasis in all eight pancreatic cancer models examined. Remarkably, several complete responses were induced by the combination treatment of dinaciclib and MK-2206. The striking results obtained in these models demonstrate that the combination of dinaciclib with the pan-AKT inhibitor MK-2206 is promising for therapeutic evaluation in pancreatic cancer, and strongly suggest that blocking RAL in combination with other effector pathways downstream from KRAS may provide increased efficacy in pancreatic cancer. Based on these data, an NCI-CTEP-approved multicenter phase I clinical trial for pancreatic cancer of the combination of dinaciclib and MK-2206 (NCT01783171) has now been opened.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Pancreatic Neoplasms/drug therapy , Tumor Burden/drug effects , Xenograft Model Antitumor Assays/methods , Administration, Oral , Animals , Apoptosis/drug effects , Bridged Bicyclo Compounds, Heterocyclic/administration & dosage , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Cell Proliferation/drug effects , Cyclic N-Oxides , Cyclin-Dependent Kinase 5/antagonists & inhibitors , Cyclin-Dependent Kinase 5/metabolism , Drug Administration Schedule , Heterocyclic Compounds, 3-Ring/administration & dosage , Heterocyclic Compounds, 3-Ring/pharmacology , Humans , Immunohistochemistry , Indolizines , Injections, Intraperitoneal , Mice, Nude , Neoplasm Metastasis , Pancreatic Neoplasms/metabolism , Pancreatic Neoplasms/pathology , Phosphorylation/drug effects , Proto-Oncogene Proteins c-akt/antagonists & inhibitors , Proto-Oncogene Proteins c-akt/metabolism , Pyridinium Compounds/administration & dosage , Pyridinium Compounds/pharmacology , Retinoblastoma Protein/metabolism , Treatment OutcomeABSTRACT
Cyclin-dependent kinase 5 (CDK5) is a potential target for prostate cancer treatment, the enzyme being essential for prostate tumor growth and formation of metastases. In the present study, we identified agents that target prostate cancer cells based on CDK5 expression. CDK5 activity was suppressed by transfection of PC3 prostate cancer cells with a dominant-negative construct (PC3 CDK5dn). PC3 CDK5dn and PC3 control cells were screened for compounds that selectively target cells based on CDK5 expression, utilizing the Johns Hopkins Drug Library. MTS proliferation, clonogenic and 3D growth assays were performed to validate the selected hits. Screening of 3,360 compounds identified rutilantin, ethacridine lactate and cetalkonium chloride as compounds that selectively target PC3 control cells and a tilorone analog as a selective inhibitor of PC3 CDK5dn cells. A PubMed literature study indicated that tilorone may have clinical use in patients. Validation experiments confirmed that tilorone treatment resulted in decreased PC3 cell growth and invasion; PC3 cells with inactive CDK5 were inhibited more effectively. Future studies are needed to unravel the mechanism of action of tilorone in CDK5 deficient prostate cancer cells and to test combination therapies with tilorone and a CDK5 inhibitor for its potential use in clinical practice.
Subject(s)
Antineoplastic Agents/pharmacology , Cyclin-Dependent Kinase 5/metabolism , Neoplasm Invasiveness/pathology , Prostatic Neoplasms/pathology , Tilorone/pharmacology , Cell Line, Tumor , Cell Proliferation/drug effects , Gene Expression Regulation, Neoplastic/drug effects , Humans , Male , Prostatic Neoplasms/metabolism , Small Molecule Libraries/pharmacologyABSTRACT
Pancreatic cancer is one of the most lethal of human malignancies, and potent therapeutic options are lacking. Inhibition of cell cycle progression through pharmacological blockade of cyclin-dependent kinases (CDK) has been suggested as a potential treatment option for human cancers with deregulated cell cycle control. Dinaciclib (SCH727965) is a novel small molecule multi-CDK inhibitor with low nanomolar potency against CDK1, CDK2, CDK5 and CDK9 that has shown favorable toxicity and efficacy in preliminary mouse experiments, and has been well tolerated in Phase I clinical trials. In the current study, the therapeutic efficacy of SCH727965 on human pancreatic cancer cells was tested using in vitro and in vivo model systems. Treatment with SCH727965 significantly reduced in vitro cell growth, motility and colony formation in soft agar of MIAPaCa-2 and Pa20C cells. These phenotypic changes were accompanied by marked reduction of phosphorylation of Retinoblastoma (Rb) and reduced activation of RalA. Single agent therapy with SCH727965 (40 mg/kg i.p. twice weekly) for 4 weeks significantly reduced subcutaneous tumor growth in 10/10 (100%) of tested low-passage human pancreatic cancer xenografts. Treatment of low passage pancreatic cancer xenografts with a combination of SCH727965 and gemcitabine was significantly more effective than either agent alone. Gene Set Enrichment Analysis identified overrepresentation of the Notch and Transforming Growth Factor-ß (TGF-ß) signaling pathways in the xenografts least responsive to SCH727965 treatment. Treatment with the cyclin-dependent kinase inhibitor SCH727965 alone or in combination is a highly promising novel experimental therapeutic strategy against pancreatic cancer.
Subject(s)
Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Cyclin-Dependent Kinases/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Pancreatic Neoplasms/drug therapy , Pyridinium Compounds/pharmacology , Animals , Antineoplastic Combined Chemotherapy Protocols/pharmacology , Bridged Bicyclo Compounds, Heterocyclic/administration & dosage , Cell Line, Tumor , Cell Movement/drug effects , Cell Proliferation/drug effects , Cyclic N-Oxides , Deoxycytidine/administration & dosage , Deoxycytidine/analogs & derivatives , Deoxycytidine/pharmacology , Drug Resistance, Neoplasm/genetics , Humans , Indolizines , Male , Mice , Mice, Nude , Pancreatic Neoplasms/embryology , Pancreatic Neoplasms/genetics , Pancreatic Neoplasms/pathology , Phosphorylation/drug effects , Pyridinium Compounds/administration & dosage , Receptors, Notch/genetics , Receptors, Notch/metabolism , Retinoblastoma Protein/metabolism , Signal Transduction , Transforming Growth Factor beta/metabolism , Xenograft Model Antitumor Assays , ral GTP-Binding Proteins/metabolism , GemcitabineABSTRACT
Hepatocellular carcinoma (HCC) is characterized by multiple somatic mutations, including DNA rearrangements, that affect many cell-growth regulatory pathways. Many genes differentially expressed in HCC have been reported previously, but the patterns of expression varied significantly between patients who bore different risk factors for HCC. To identify genes whose differential expression could serve as a "signature" for diagnosis and prognosis of HCC, we performed analyses of differentially expressed genes in three cases of HCC with different risk factors using the Atlas Human Cancer cDNA Expression Arrays. Among all 597 genes present on the array, only three were found to be coordinately differentially expressed in all three HCC cases, in agreement with published data. These three genes, Cu/Zn superoxide dismutase, osteonectin/secreted protein acidic and rich in cysteine, and matrix metalloproteinase 14, could serve as candidates for the HCC "signature." Ten genes were found to be coordinately differentially expressed in only two of three tested HCC cases. On the other hand, many genes that had been reported previously as differentially expressed in HCC failed to show the described pattern of expression in this group. The results of this study confirm the great variability in gene-expression patterns in HCC and establish the utility of the array technology for identifying both the HCC signature genes and individual gene-expression patterns for purposes of patient-oriented therapy.
