Sorafenib attenuates p21 in kidney cancer cells and augments cell death in combination with DNA-damaging chemotherapy

Cancer selective cell death induction by a bivalent CK2 inhibitor targeting the ATP site and the allosteric αD pocket

Although the involvement of protein kinase CK2 in cancer is well-documented, there is a need for selective CK2 inhibitors suitable for investigating CK2 specific roles in cancer-related biological pathways and further exploring its therapeutic potential. Here, we report the discovery of AB668, an outstanding selective inhibitor that binds CK2 through a bivalent mode, interacting both at the ATP site and an allosteric αD pocket unique to CK2. Using caspase activation assay, live-cell imaging, and transcriptomic analysis, we have compared the effects of this bivalent inhibitor to representative ATP-competitive inhibitors, CX-4945, and SGC-CK2-1. Our results show that in contrast to CX-4945 or SGC-CK2-1, AB668, by targeting the CK2 αD pocket, has a distinct mechanism of action regarding its anti-cancer activity, inducing apoptotic cell death in several cancer cell lines and stimulating distinct biological pathways in renal cell carcinoma.

CDKN1A/p21 in Breast Cancer: Part of the Problem, or Part of the Solution?

Cyclin-dependent kinase inhibitor 1A (Cip1/Waf1/CDKN1A/p21) is a well-established protein, primarily recognised for its pivotal role in the cell cycle, where it induces cell cycle arrest by inhibiting the activity of cyclin-dependent kinases (CDKs). Over the years, extensive research has shed light on various additional mechanisms involving CDKN1A/p21, implicating it in processes such as apoptosis, DNA damage response (DDR), and the regulation of stem cell fate. Interestingly, p21 can function either as an oncogene or as a tumour suppressor in these contexts. Complicating matters further, the expression of CDKN1A/p21 is elevated in certain tumour types while downregulated in others. In this comprehensive review, we provide an overview of the multifaceted functions of CDKN1A/p21, present clinical data pertaining to cancer patients, and delve into potential strategies for targeting CDKN1A/p21 as a therapeutic approach to cancer. Manipulating CDKN1A/p21 shows great promise for therapy given its involvement in multiple cancer hallmarks, such as sustained cell proliferation, the renewal of cancer stem cells (CSCs), epithelial-mesenchymal transition (EMT), cell migration, and resistance to chemotherapy. Given the dual role of CDKN1A/p21 in these processes, a more in-depth understanding of its specific mechanisms of action and its regulatory network is imperative to establishing successful therapeutic interventions.

Rumex vesicarius L. boosts the effectiveness of sorafenib in triple-negative breast cancer by downregulating BCl2, mTOR, and JNK, and upregulating p21 expression

BACKGROUND/AIM

Triple-negative breast cancer (TNBC) is characterized by poor prognosis, rapid progression, serious clinical behavior, an elevated risk of metastasis, and resistance to standard treatments. Traditional medicine practitioners value Rumex vesicarius L. (RMV) for a variety of reasons, including the plant's antioxidant capabilities. Our study's goals were to ascertain the efficacy of RMV alone and in combination with sorafenib (SOR) against the aggressive TNBC cell line (MDA-MB-231) and use in vitro and in silico analysis to deduce the fundamental mechanism of action.

METHODS

In the current study, molecular operating environment (MOE, 2019.0102) software was used for performing molecular docking. The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay was used to determine the cytotoxicity of RMV, SOR or RMV/SOR combination against the TNBC cell line MDA-MB-231 cells. The effects of RMV, SOR, and RMV and SOR combining on mRNAs expressions of the target genes including mTOR, p21, JNK, and BCl2 were evaluated. In TNBC cells, the relative expressions of mRNAs of the genes were examined by using real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

In our experiments, we discovered that both RMV extracts alone and in combination with SOR considerably reduced cancer cell proliferation (IC50 = 0.83 and 0.19 μM, respectively). Additionally, the expression of the tumor suppressor gene p21 was elevated whereas the expression of the invasion and anti-apoptosis genes BCl2, mTOR, and JNK were significantly decreased after treatment with RMV and SOR. Based on in silico analysis, it was found that RMV extract contains bioactive chemicals with a high affinity for inhibiting JNK and VEGFR-2.

CONCLUSION

In conclusion, in vitro and in silico investigations show that the RMV extract improves the anticancer efficiency of SOR through molecular processes involving the downregulation of mTOR, BCl2, and JNK1 and overexpression of p21 tumor suppressor gene. Finally, we suggest conducting additional in vivo investigations on RMV and its bioactive components to verify their potential in cancer therapy.

Targeting hyaluronic acid synthase-3 (HAS3) for the treatment of advanced renal cell carcinoma

BACKGROUND

Hyaluronic acid (HA) promotes cancer metastasis; however, the currently approved treatments do not target HA. Metastatic renal carcinoma (mRCC) is an incurable disease. Sorafenib (SF) is a modestly effective antiangiogenic drug for mRCC. Although only endothelial cells express known SF targets, SF is cytotoxic to RCC cells at concentrations higher than the pharmacological-dose (5-µM). Using patient cohorts, mRCC models, and SF combination with 4-methylumbelliferone (MU), we discovered an SF target in RCC cells and targeted it for treatment.

METHODS

We analyzed HA-synthase (HAS1, HAS2, HAS3) expression in RCC cells and clinical (n = 129), TCGA-KIRC (n = 542), and TCGA-KIRP (n = 291) cohorts. We evaluated the efficacy of SF and SF plus MU combination in RCC cells, HAS3-transfectants, endothelial-RCC co-cultures, and xenografts.

RESULTS

RCC cells showed increased HAS3 expression. In the clinical and TCGA-KIRC/TCGA-KIRP cohorts, higher HAS3 levels predicted metastasis and shorter survival. At > 10-µM dose, SF inhibited HAS3/HA-synthesis and RCC cell growth. However, at ≤ 5-µM dose SF in combination with MU inhibited HAS3/HA synthesis, growth of RCC cells and endothelial-RCC co-cultures, and induced apoptosis. The combination inhibited motility/invasion and an HA-signaling-related invasive-signature. We previously showed that MU inhibits SF inactivation in RCC cells. While HAS3-knockdown transfectants were sensitive to SF, ectopic-HAS3-expression induced resistance to the combination. In RCC models, the combination inhibited tumor growth and metastasis with little toxicity; however, ectopic-HAS3-expressing tumors were resistant.

CONCLUSION

HAS3 is the first known target of SF in RCC cells. In combination with MU (human equivalent-dose, 0.6-1.1-g/day), SF targets HAS3 and effectively abrogates mRCC.

The cyclin dependent kinase inhibitor p21Cip1/Waf1 is a therapeutic target in high-risk neuroblastoma

Platinum-based chemotherapies such as cisplatin are used as first-line treatment for the paediatric tumour neuroblastoma. Although the majority of neuroblastoma tumours respond to therapy, there is a high fraction of high-risk neuroblastoma patients that eventually relapse with increased resistance. Here, we show that one key determinant of cisplatin sensitivity is phosphorylation of the cyclin-dependent kinase inhibitor p21^Cip1/Waf1. A panel of eight neuroblastoma cell lines and a TH-MYCN mouse model were investigated for the expression of p21^Cip1/Waf1 using RT-qPCR, Western blot, and immunofluorescence. This was followed by investigation of sensitivity towards cisplatin and the p21^Cip1/Waf1 inhibitor UC2288. Whereas the cell lines and the mouse model showed low levels of un-phosphorylated p21^Cip1/Waf1, the phosphorylated p21^Cip1/Waf1 (Thr145) was highly expressed, which in the cell lines correlated to cisplatin resistance. Furthermore, the neuroblastoma cell lines showed high sensitivity to UC2288, and combination treatment with cisplatin resulted in considerably decreased cell viability and delay in regrowth in the two most resistant cell lines, SK-N-DZ and BE(2)-C. Thus, targeting p21^Cip1/Waf1 can offer new treatment strategies and subsequently lead to the design of more efficient combination treatments for high-risk neuroblastoma.

Genetic and Histopathological Heterogeneity of Neuroblastoma and Precision Therapeutic Approaches for Extremely Unfavorable Histology Subgroups

Peripheral neuroblastic tumors (neuroblastoma, ganglioneuroblastoma and ganglioneuroma) are heterogeneous and their diverse and wide range of clinical behaviors (spontaneous regression, tumor maturation and aggressive progression) are closely associated with genetic/molecular properties of the individual tumors. The International Neuroblastoma Pathology Classification, a biologically relevant and prognostically significant morphology classification distinguishing the favorable histology (FH) and unfavorable histology (UH) groups in this disease, predicts survival probabilities of the patients with the highest hazard ratio. The recent advance of neuroblastoma research with precision medicine approaches demonstrates that tumors in the UH group are also heterogeneous and four distinct subgroups—MYC, TERT, ALT and null—are identified. Among them, the first three subgroups are collectively named extremely unfavorable histology (EUH) tumors because of their highly aggressive clinical behavior. As indicated by their names, these EUH tumors are individually defined by their potential targets detected molecularly and immunohistochemically, such as MYC-family protein overexpression, TERT overexpression and ATRX (or DAXX) loss. In the latter half on this paper, the current status of therapeutic targeting of these EUH tumors is discussed for the future development of effective treatments of the patients.

Sorafenib, rapamycin, and venetoclax attenuate doxorubicin-induced senescence and promote apoptosis in HCT116 cells

Emerging evidence has shown that the therapy-induced senescent growth arrest in cancer cells is of durable nature whereby a subset of cells can reinstate proliferative capacity. Promising new drugs named senolytics selectively target senescent cells and commit them into apoptosis. Accordingly, senolytics have been proposed as adjuvant cancer treatment to cull senescent tumor cells, and thus, screening for agents that exhibit senolytic properties is highly warranted. Our study aimed to investigate three agents, sorafenib, rapamycin, and venetoclax for their senolytic potential in doxorubicin-induced senescence in HCT116 cells. HCT116 cells were treated with one of the three agents, sorafenib (5 µM), rapamycin (100 nM), or venetoclax (10 µM), in the absence or presence of doxorubicin (1 µM). Senescence was evaluated using microscopy-based and flow cytometry-based Senescence-associated-β-galactosidase staining (SA-β-gal), while apoptosis was assessed using annexin V-FITC/PI, and Muse caspase-3/-7 activity assays. We screened for potential genes through which the three drugs exerted senolytic-like action using the Human Cancer Pathway Finder PCR array. The three agents reduced doxorubicin-induced senescent cell subpopulations and significantly enhanced the apoptotic effect of doxorubicin compared with those treated only with doxorubicin. The senescence genes IGFBP5 and BMI1 and the apoptosis genes CASP7 and CASP9 emerged as candidate genes through which the three drugs exhibited senolytic-like properties. These results suggest that the attenuation of doxorubicin-induced senescence might have shifted HCT116 cells to apoptosis by exposure to the tested pharmacological agents. Our work argues for the use of senolytics to reduce senescence-mediated resistance in tumor cells and to enhance chemotherapy efficacy.

RNA sequencing of long-term label-retaining colon cancer stem cells identifies novel regulators of quiescence

Recent data suggest that therapy-resistant quiescent cancer stem cells (qCSCs) are the source of relapse in colon cancer. Here, using colon cancer patient-derived organoids and xenografts, we identify rare long-term label-retaining qCSCs that can re-enter the cell cycle to generate new tumors. RNA sequencing analyses demonstrated that these cells display the molecular hallmarks of quiescent tissue stem cells, including expression of p53 signaling genes, and are enriched for transcripts common to damage-induced quiescent revival stem cells of the regenerating intestine. In addition, we identify negative regulators of cell cycle, downstream of p53, that we show are indicators of poor prognosis and may be targeted for qCSC abolition in both p53 wild-type and mutant tumors. These data support the temporal inhibition of downstream targets of p53 signaling, in combination with standard-of-care treatments, for the elimination of qCSCs and prevention of relapse in colon cancer.

•

Colon tumors contain therapy-resistant quiescent cancer stem cells (qCSCs)

•

qCSC gene expression mirrors that of quiescent stem cells of the regenerating gut

•

qCSCs are enriched for p53 signaling genes

•

qCSC elimination may be achieved by inhibiting downstream targets of p53 signaling

Permutation-based identification of important biomarkers for complex diseases via machine learning models

Study of human disease remains challenging due to convoluted disease etiologies and complex molecular mechanisms at genetic, genomic, and proteomic levels. Many machine learning-based methods have been developed and widely used to alleviate some analytic challenges in complex human disease studies. While enjoying the modeling flexibility and robustness, these model frameworks suffer from non-transparency and difficulty in interpreting each individual feature due to their sophisticated algorithms. However, identifying important biomarkers is a critical pursuit towards assisting researchers to establish novel hypotheses regarding prevention, diagnosis and treatment of complex human diseases. Herein, we propose a Permutation-based Feature Importance Test (PermFIT) for estimating and testing the feature importance, and for assisting interpretation of individual feature in complex frameworks, including deep neural networks, random forests, and support vector machines. PermFIT (available at https://github.com/SkadiEye/deepTL) is implemented in a computationally efficient manner, without model refitting. We conduct extensive numerical studies under various scenarios, and show that PermFIT not only yields valid statistical inference, but also improves the prediction accuracy of machine learning models. With the application to the Cancer Genome Atlas kidney tumor data and the HITChip atlas data, PermFIT demonstrates its practical usage in identifying important biomarkers and boosting model prediction performance.

Study of human disease remains challenging due to convoluted disease etiologies and complex molecular mechanisms at genetic, genomic, and proteomic levels. Here, the authors propose a computationally efficient Permutation-based Feature Importance Test to assist interpretation and selection of individual features in complex machine learning models for complex disease analysis.

Mitochondrial dynamics imbalance and mitochondrial dysfunction contribute to the molecular cardiotoxic effects of lenvatinib

Lenvatinib is a tyrosine kinase inhibitor (TKI) approved for the treatment of resistant differentiated thyroid cancer, advanced renal cell carcinoma, unresectable hepatocellular carcinoma, and endometrial carcinoma. Although it is successful in cancer treatment, it can cause life-threatening side effects such as cardiotoxicity. The molecular mechanism of cardiotoxicity caused by lenvatinib is not fully known. In this study, the molecular mechanism of lenvatinib's cardiotoxicity was investigated focusing on mitochondrial toxicity in the H9c2 cardiomyoblastic cell line. Lenvatinib inhibited cell viability at 48 and 72 h exposure with three selected concentrations (1.25 μM, 5 μM and 10 μM); and inhibited intracellular ATP after 72 h exposure compared to the control group. Mitochondrial membrane potential was decreased after 48 h and did not show significant changes after 72 h exposure. Evaluated with real-time PCR, mitochondrial dynamics (Mfn1, Mfn2, OPA1, DRP1, Fis1) expression levels after lenvatinib treatment significantly changed. Lenvatinib triggered the tendency from fusion to fission in mitochondria after 48 h exposure, and increased both fusion and fission after 72 h. The mtDNA ratio increased after 48 h and decreased after 72 h. ASK1, JNK and AMPKα2 increased. UCP2 showed downregulation, SOD2 level showed upregulation and Cat levels decreased after drug treatment. Nrf1 and Nrf2 also changed concentration-dependently. Protein carbonyl levels increased significantly after lenvatinib treatments indicating oxidative stress. The protein levels of the electron transport chain complexes, LONP1, UCP2, and P21 showed significant differences after lenvatinib treatment. The outcome of our study is expected to be a contribution to the understanding of the molecular mechanisms of TKI-induced cardiotoxicity.

Synergistic Anticancer Activity of N-Hydroxy-7-(2-Naphthylthio) Heptanomide, Sorafenib, and Radiation Therapy in Patient-Derived Anaplastic Thyroid Cancer Models

Anaplastic thyroid cancer (ATC) is an undifferentiated and advanced form of thyroid cancer, accompanied with a high ratio of epigenetic adjustment, which occurs more than genetic mutations. In this study, we aimed to evaluate the synergistic anticancer effect (in vitro and in vivo) of the new combination of N-hydroxy-7-(2-naphthylthio) heptanomide (HNHA) and sorafenib with radiation therapy in pre-clinical models of ATC. The ATC cell lines, YUMC-A1 and YUMC-A2, were isolated from the current patients who were treated with HNHA and sorafenib, either as monotherapy or combination therapy. Synergistic anticancer effect of the combination therapy on the intracellular signaling pathways and cell cycle was assessed via flow cytometry and immunoblot analysis. To examine tumor shrinkage activity in vivo, an ATC cell line-derived mouse xenograft model was used. Results showed that the combination therapy of HNHA and sorafenib with radiation promoted tumor suppression via caspase cleavage and cell cycle arrest in patient-derived ATC. In addition, the combination therapy of HNHA and sorafenib with radiation was more effective against ATC than therapy with HNHA or sorafenib with radiation. Thus, the combination of HNHA and sorafenib with radiation may be used as a novel curative approach for the treatment of ATC.

Synergistic anticancer activity of sorafenib, paclitaxel, and radiation therapy on anaplastic thyroid cancer in vitro and in vivo

BACKGROUND

This study aimed to investigate the antitumor activity of paclitaxel with radiation and sorafenib in anaplastic thyroid cancer (ATC) cells in vitro and in vivo.

METHODS

The 8505C ATC cell line was exposed to radiation, sorafenib, and paclitaxel each or in combination. The effects of combined treatment on the cell cycle and intracellular signaling pathways were assessed using flow cytometry and western blot analysis. An ATC cell line xenograft model was used to examine antitumor activity in vivo.

RESULTS

Radiation, paclitaxel plus sorafenib synergistically decreased cell viability in ATC cells and significantly increased apoptotic cell death. The combination of paclitaxel, sorafenib with radiation reduced the antiapoptotic factor in ATC. This combination therapy significantly reduced the tumor volume and increased survival in the ATC xenograft model.

CONCLUSIONS

These results suggest that the combination of radiation and paclitaxel plus sorafenib has significant anticancer activity in preclinical models.

Anti-Cancer Activity of PAK4/NAMPT Inhibitor and Programmed Cell Death Protein-1 Antibody in Kidney Cancer

BACKGROUND

Kidney cancer (or renal cell carcinoma, RCC) is the sixth most common malignancy in the United States and is increasing in incidence. Despite new therapies, including targeted therapies and immunotherapies, most RCCs are resistant to treatment. Thus, several laboratories have been evaluating new approaches to therapy, both with single agents as well as combinations. Although we have previously shown efficacy of the dual PAK4/nicotinamide phosphoribosyltransferase (NAMPT) inhibitor KPT-9274, and the immune checkpoint inhibitors (CPI) have shown utility in the clinic, there has been no evaluation of this combination either clinically or in an immunocompetent animal model of kidney cancer.

METHODS

In this study, we use the renal cell adenocarcinoma (RENCA) model of spontaneous murine kidney cancer. Male BALB/cJ mice were injected subcutaneously with RENCA cells and, after tumors were palpable, they were treated with KPT-9274 and/or anti-programmed cell death 1 (PDCD1; PD1) antibody for 21 days. Tumors were measured and then removed at animal euthanasia for subsequent studies.

RESULTS

We demonstrate a significant decrease in allograft growth with the combination treatment of KPT-9274 and anti-PD1 antibody without significant weight loss by the animals. This is associated with decreased (MOUSE) Naprt expression, indicating dependence of these tumors on NAMPT in parallel to what we have observed in human RCC. Histology of the tumors showed substantial necrosis regardless of treatment condition, and flow cytometry of antibody-stained tumor cells revealed that the enhanced therapeutic effect of KPT-9274 and anti-PD1 antibody was not driven by infiltration of T cells into tumors.

CONCLUSIONS

This study highlights the potential of the RENCA model for evaluating immunologic responses to KPT-9274 and checkpoint inhibitor (CPI) and suggests that therapy with this combination could improve efficacy in RCC beyond what is achievable with CPI alone.

Casein Kinase 1 Delta Regulates Cell Proliferation, Response to Chemotherapy and Migration in Human Ovarian Cancer Cells

Casein kinase 1 delta (CK1δ) has a tumor-promoting role in different cancers and it is genetically amplified in a portion of human epithelial ovarian cancer (EOC). CK1δ is involved in pleiotropic cellular functions such as cell proliferation, DNA damage, and migration. We specifically knocked down CK1δ by short hairpin RNA (shRNA) in human ovarian cancer cells and we performed proliferation, chemosensitivity, as well as in vitro and in vivo migration assays. CK1δ knocked-down cells displayed reduced proliferation capability both in vitro and in vivo. Nonetheless, these cells were sensitized to the first line chemotherapeutic agent carboplatin (CPT), and this observation could be associated to reduced expression levels of p21(Cip1/Waf1), involved in DNA damage response, and the anti-apoptotic X-linked inhibitor of apoptosis protein (XIAP). Moreover, CK1δ knocked-down cells were affected in their migratory and lung homing capability, even if in opposite ways, i.e., IGROV1, SKOV3 and MES-OV lost, while OVCAR3 gained motility potential. The results suggest CK1δ as a potential exploitable target for pharmacological EOC treatment, but they also advise further investigation of its role in cell migration.

The Multifaceted p21 (Cip1/Waf1/CDKN1A) in Cell Differentiation, Migration and Cancer Therapy

Loss of cell cycle control is characteristic of tumorigenesis. The protein p21 is the founding member of cyclin-dependent kinase inhibitors and an important versatile cell cycle protein. p21 is transcriptionally controlled by p53 and p53-independent pathways. Its expression is increased in response to various intra- and extracellular stimuli to arrest the cell cycle ensuring genomic stability. Apart from its roles in cell cycle regulation including mitosis, p21 is involved in differentiation, cell migration, cytoskeletal dynamics, apoptosis, transcription, DNA repair, reprogramming of induced pluripotent stem cells, autophagy and the onset of senescence. p21 acts either as a tumor suppressor or as an oncogene depending largely on the cellular context, its subcellular localization and posttranslational modifications. In the present review, we briefly mention the general functions of p21 and summarize its roles in differentiation, migration and invasion in detail. Finally, regarding its dual role as tumor suppressor and oncogene, we highlight the potential, difficulties and risks of using p21 as a biomarker as well as a therapeutic target.

Melatonin and (-)-Epigallocatechin-3-Gallate: Partners in Fighting Cancer

We have demonstrated previously that melatonin attenuates hepatotoxicity triggered by high doses of (−)-epigallocatechin-3-gallate (EGCG) in mice. The current work investigated the influence of melatonin on the oncostatic activity of EGCG in two cancer cell lines, wherein melatonin induced an opposite response of p21. In human tongue cancer TCA8113 cells, melatonin-induced p21 and EGCG-mediated formation of quinoproteins were positively associated with the oncostatic effects of melatonin and EGCG. Melatonin-stimulated an increase in p21 which was correlated with a pronounced nuclear translocation of thioredoxin 1 and thioredoxin reductase 1, both of which are known to induce p21 via promoting p53 trans-activation. Melatonin did not influence the EGCG-mediated increase of quinoprotein formation nor did EGCG impair melatonin-induced p21 up-regulation. Co-treatment with both agents enhanced the cell-killing effect as well as the inhibitory activities against cell migration and colony formation. It is known that p21 also plays a powerful anti-apoptotic role in some cancer cells and confers these cells with a survival advantage, making it a target for therapeutic suppression. In human hepatocellular carcinoma HepG2 cells, melatonin suppressed p21 along with the induction of pro-survival proteins, PI3K and COX-2. However, EGCG prevented against melatonin-induced PI3K and COX-2, and melatonin probably sensitized HepG2 cells to EGCG cytotoxicity via down-regulating p21, Moreover, COX-2 and HO-1 were significantly reduced only by the co-treatment, and melatonin aided EGCG to achieve an increased inhibition on Bcl2 and NFκB. These events occurring in the co-treatment collectively resulted in an enhanced cytotoxicity. In addition, the co-treatment also enhanced the inhibitory activities against cell migration and colony formation. Overall, the results gathered from these two cancer cell lines with a divergent p21 response to melatonin show that the various oncostatic activities of melatonin and EGCG together are more robust than each agent alone, suggesting that they may be useful partners in fighting cancer.

16-Hydroxycleroda-3,13-dien-15,16-olide induces anoikis in human renal cell carcinoma cells: involvement of focal adhesion disassembly and signaling

Background

Clerodane diterpene, 16-hydroxycleroda-3,13-dien-15,16-olide (CD) isolated from Polyalthia longifolia Benth. & Hook. f. var. pendula was found to be a potential apoptotic inducer in human leukemia, lung cancer, and colon cancer cells. However, the molecular mechanism remains elusive in renal system. Thus, in the present study, the regulatory mechanisms of CD-induced apoptosis in clear cell renal cell carcinoma (ccRCC) cells were investigated.

Materials and methods

Cell proliferation was evaluated by colony formation assay and cell cycle analyses. Protein expressions of focal adhesion (FA) related complexes were examined by immunofluorescence staining and Western blot analyses. Cell migration and invasion capabilities of renal cell carcinoma (RCC) cells were determined by wound healing and Transwell assays.

Results

CD inhibited cell colony formations, induced cell arrest at G2/M phase, and increased subG1 cell population both in 786-O and A-498. During CD treatment, the “rounded-up” cells were observed. The immune-staining of phosphorylated focal adhesion kinase (pFAK), vinculin, and paxillin displayed disassembly of the FA. Moreover, disruption of actin stress fibers was noted after CD treatment. Consistent with the findings, the expressions of pSrc, pFAK, FAK, vinculin, vimentin, and paxillin were all downregulated by CD. In addition, CD attenuated cell migration and invasion activities accompanied by the reductions of pNF-κB, matrix metallo-proteinase (MMP)-2, MMP-9 as well as vascular endothelial growth factor expressions.

Conclusion

CD induced cell cycle arrest, FA complex disassembly, and the inactivation of migratory-related signaling pathways to induce apoptosis in ccRCC cells.

Synergistic anti-tumor effect of bullfrog sialic acid-binding lectin and pemetrexed in malignant mesothelioma

Malignant mesothelioma is an aggressive cancer with limited therapeutic options. Sialic acid-binding lectin isolated from Rana catesbeiana oocytes (cSBL) is a multifunctional protein with anti-cancer activity. The effects of pemetrexed, cisplatin, and cSBL were evaluated in mesothelioma and normal mesothelial cell lines. We evaluated cytotoxicity, apoptosis, caspase-3 cleavage and activation, cell proliferation, cell cycle arrest, and levels of cell cycle proteins in H28 cells treated with pemetrexed, cisplatin, and cSBL alone or in combination. Treatment with cSBL alone was cytotoxic to mesothelioma cells. The anti-cancer effect of cSBL was observed in a broader range of cell lines and exhibited greater cancer cell selectivity than pemetrexed or cisplatin. Combination treatment with pemetrexed + cSBL resulted in greater dose-dependent cytotoxicity than pemetrexed + cisplatin, the standard of care in mesothelioma. The synergistic effect of pemetrexed + cSBL was mediated by the cytostatic effect of pemetrexed and the cytotoxic effect of cSBL. It thus appears that cSBL has therapeutic potential for the treatment of mesothelioma.

Inhibiting tryptophan metabolism enhances interferon therapy in kidney cancer

Renal cell carcinoma (RCC) is increasing in incidence, and a complete cure remains elusive. While immune-checkpoint antibodies are promising, interferon-based immunotherapy has been disappointing. Tryptophan metabolism, which produces immunosuppressive metabolites, is enhanced in RCC. Here we show indolamine-2,3-dioxygenase-1 (IDO1) expression, a kynurenine pathway enzyme, is increased not only in tumor cells but also in the microenvironment of human RCC compared to normal kidney tissues. Neither kynurenine metabolites nor IDO inhibitors affected the survival or proliferation of human RCC or murine renal cell adenocarcinoma (RENCA) cells in vitro. However, interferon-gamma (IFNγ) induced high levels of IDO1 in both RCC and RENCA cells, concomitant with enhanced kynurenine levels in conditioned media. Induction of IDO1 by IFNα was weaker than by IFNγ. Neither the IDO1 inhibitor methyl-thiohydantoin-DL-tryptophan (MTH-trp) nor IFNα alone inhibited RENCA tumor growth, however the combination of MTH-trp and IFNα reduced tumor growth compared to IFNα. Thus, the failure of IFNα therapy for human RCC is likely due to its inability to overcome the immunosuppressive environment created by increased IDO1. Based on our data, and given that IDO inhibitors are already in clinical trials for other malignancies, IFNα therapy with an IDO inhibitor should be revisited for RCC.

MDM2 Antagonists Counteract Drug-Induced DNA Damage

Antagonists of MDM2-p53 interaction are emerging anti-cancer drugs utilized in clinical trials for malignancies that rarely mutate p53, including melanoma. We discovered that MDM2-p53 antagonists protect DNA from drug-induced damage in melanoma cells and patient-derived xenografts. Among the tested DNA damaging drugs were various inhibitors of Aurora and Polo-like mitotic kinases, as well as traditional chemotherapy. Mitotic kinase inhibition causes mitotic slippage, DNA re-replication, and polyploidy. Here we show that re-replication of the polyploid genome generates replicative stress which leads to DNA damage. MDM2-p53 antagonists relieve replicative stress via the p53-dependent activation of p21 which inhibits DNA replication. Loss of p21 promoted drug-induced DNA damage in melanoma cells and enhanced anti-tumor activity of therapy combining MDM2 antagonist with mitotic kinase inhibitor in mice. In summary, MDM2 antagonists may reduce DNA damaging effects of anti-cancer drugs if they are administered together, while targeting p21 can improve the efficacy of such combinations.

Anticystogenic activity of a small molecule PAK4 inhibitor may be a novel treatment for autosomal dominant polycystic kidney disease

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a common hereditary renal disease with no currently available targeted therapies. Based on the established connection between β-catenin signaling and renal ciliopathies, and on data from our and other laboratories showing striking similarities of this disease and cancer, we evaluated the use of an orally bioavailable small molecule, KPT-9274 (a dual inhibitor of the protein kinase PAK4 and nicotinamide phosphoribosyl transferase), for treatment of ADPKD. Treatment of PKD-derived cells with this compound not only reduces PAK4 steady-state protein levels and regulates β-catenin signaling, but also inhibits nicotinamide phosphoribosyl transferase, the rate-limiting enzyme in a key NAD salvage pathway. KPT-9274 can attenuate cellular proliferation and induce apoptosis associated with a decrease in active (phosphorylated) PAK4 and β-catenin in several Pkd1-null murine cell lines, with a less pronounced effect on the corresponding phenotypically normal cells. Additionally, KPT-9274 shows inhibition of cystogenesis in an ex vivo model of cyclic AMP-induced cystogenesis as well as in the early stage Pkd1^flox/flox:Pkhd1-Cre mouse model, the latter showing confirmation of specific anti-proliferative, apoptotic, and on-target effects. NAD biosynthetic attenuation by KPT-9274, while critical for highly proliferative cancer cells, does not appear to be important in the slower growing cystic epithelial cells during cystogenesis. KPT-9274 was not toxic in our ADPKD animal model or in other cancer models. Thus, this small molecule inhibitor could be evaluated in a clinical trial as a viable therapy of ADPKD.

MicroRNA-125a-5p Is a Downstream Effector of Sorafenib in Its Antiproliferative Activity Toward Human Hepatocellular Carcinoma Cells

Sorafenib is an antitumor drug for treatment of advanced hepatocellular carcinoma (HCC). It acts as a multikinase inhibitor suppressing cell proliferation and angiogenesis. Human microRNA-125a-5p (miR-125a) is endowed with similar activities and is frequently downregulated in HCC. Looking for a potential microRNA-based mechanism of action of the drug, we found that sorafenib increases cellular expression of miR-125a in cultured HuH-7 and HepG2 HCC cells. Upregulation of the microRNA inhibited cell proliferation by suppression of sirtuin-7, a NAD(+)-dependent deacetylase, and p21/p27-dependent cell cycle arrest in G1. Later, recruitment of miR-125a in the antiproliferative activity of sorafenib was inquired by modulating its expression in combination with the drug treatment. This analysis showed that intracellular delivery of miR-125a had no additive effect on the antiproliferative activity of sorafenib, whereas a miR-125a inhibitor could counteract it. Finally, evaluation of other oncogenic targets of miR-125a revealed its ability to interfere with the expression of matrix metalloproteinase-11, Zbtb7a proto-oncogene, and c-Raf, possibly contributing to the antiproliferative activity of the drug. J. Cell. Physiol. 232: 1907-1913, 2017. © 2016 Wiley Periodicals, Inc.

Synergistic Activity of N-hydroxy-7-(2-naphthylthio) Heptanomide and Sorafenib Against Cancer Stem Cells, Anaplastic Thyroid Cancer

Anaplastic thyroid carcinoma (ATC) although rare is the most deadly form of thyroid cancer. The fatality rate for ATC is high-pitched, the survival rate at 1 year after diagnosis is <20%. Control of ATC is severely hard and widespread with unpredictability. We Previous proved that histone gene reviser and epigenetic changes role significant parts in papillary and anaplastic thyroid cancer tumorigenesis. Herein, the goal of this study was to investigate the anti-tumor activities of a HDAC inhibitor, HNHA alone and in combination with sorafenib in ATC cells in vitro and in vivo and to explore its effects on apoptotic cell death pathways. Three ATC cell lines were exposed to sorafenib in the presence or absence of HNHA, and cell viability was determined by MTT assay. Effects of combined treatment on cell cycle and intracellular signaling pathways were assessed by flow cytometry and western blot analysis. The ATC cell lines xenograft model was used to examine the anti-tumor activity in vivo. Our data showed that HNHA and sorafenib synergistically decreased cell viability in ATC cells, and also significantly increased apoptotic cell death in these cells, as proved by the cleavage of caspase-3 and DNA fragmentation. HNHA and sorafenib combination was reduced anti-apoptotic factor in ATC. Thus, combination therapy with HNHA and sorafenib significantly decreased vessel density, and most significantly reduced tumor volume and increased survival in ATC xenografts.

These results propose that HNHA in combination with sorafenib has significant anti-cancer activity in preclinical models, potentially suggesting a new clinical approach for patients of advanced thyroid cancer type.

Dual and Specific Inhibition of NAMPT and PAK4 By KPT-9274 Decreases Kidney Cancer Growth

Kidney cancer (or renal cell carcinoma, RCC) is the sixth most common malignancy in the United States and one of the relatively few whose incidence is increasing. Because of the near universal resistance which occurs with the use of current treatment regimens, reprogrammed metabolic pathways are being investigated as potential targets for novel therapies of this disease. Borrowing from studies on other malignancies, we have identified the PAK4 and NAD biosynthetic pathways as being essential for RCC growth. We now show, using the dual PAK4/NAMPT inhibitor KPT-9274, that interference with these signaling pathways results in reduction of G2-M transit as well as induction of apoptosis and decrease in cell invasion and migration in several human RCC cell lines. Mechanistic studies demonstrate that inhibition of the PAK4 pathway by KPT-9274 attenuates nuclear β-catenin as well as the Wnt/β-catenin targets cyclin D1 and c-Myc. Furthermore, NAPRT1 downregulation, which we show occurs in all RCC cell lines tested, makes this tumor highly dependent on NAMPT for its NAD requirements, such that inhibition of NAMPT by KPT-9274 leads to decreased survival of these rapidly proliferating cells. When KPT-9274 was administered in vivo to a 786-O (VHL-mut) human RCC xenograft model, there was dose-dependent inhibition of tumor growth with no apparent toxicity; KPT-9274 demonstrated the expected on-target effects in this mouse model. KPT-9274 is being evaluated in a phase I human clinical trial in solid tumors and lymphomas, which will allow this data to be rapidly translated into the clinic for the treatment of RCC. Mol Cancer Ther; 15(9); 2119-29. ©2016 AACR.

Role of Mitochondrial DNA Copy Number Alteration in Human Renal Cell Carcinoma

We investigated the role of mitochondrial DNA (mtDNA) copy number alteration in human renal cell carcinoma (RCC). The mtDNA copy numbers of paired cancer and non-cancer parts from five resected RCC kidneys after radical nephrectomy were determined by quantitative polymerase chain reaction (Q-PCR). An RCC cell line, 786-O, was infected by lentiviral particles to knock down mitochondrial transcriptional factor A (TFAM). Null target (NT) and TFAM-knockdown (TFAM-KD) represented the control and knockdown 786-O clones, respectively. Protein or mRNA expression levels of TFAM; mtDNA-encoded NADH dehydrogenase subunit 1 (ND1), ND6 and cytochrome c oxidase subunit 2 (COX-2); nuclear DNA (nDNA)-encoded succinate dehydrogenase subunit A (SDHA); v-akt murine thymoma viral oncogene homolog 1 gene (AKT)-encoded AKT and v-myc myelocytomatosis viral oncogene homolog gene (c-MYC)-encoded MYC; glycolytic enzymes including hexokinase II (HK-II), glucose 6-phosphate isomerase (GPI), phosphofructokinase (PFK), and lactate dehydrogenase subunit A (LDHA); and hypoxia-inducible factors the HIF-1α and HIF-2α, pyruvate dehydrogenase kinase 1 (PDK1), and pyruvate dehydrogenase E1 component α subunit (PDHA1) were analyzed by Western blot or Q-PCR. Bioenergetic parameters of cellular metabolism, basal mitochondrial oxygen consumption rate (mOCR_B) and basal extracellular acidification rate (ECAR_B), were measured by a Seahorse XF^e-24 analyzer. Cell invasiveness was evaluated by a trans-well migration assay and vimentin expression. Doxorubicin was used as a chemotherapeutic agent. The results showed a decrease of mtDNA copy numbers in resected RCC tissues (p = 0.043). The TFAM-KD clone expressed lower mtDNA copy number (p = 0.034), lower mRNA levels of TFAM (p = 0.008), ND1 (p = 0.007), and ND6 (p = 0.017), and lower protein levels of TFAM and COX-2 than did the NT clone. By contrast, the protein levels of HIF-2α, HK-II, PFK, LDHA, AKT, MYC and vimentin; trans-well migration activity (p = 0.007); and drug resistance to doxorubicin (p = 0.008) of the TFAM-KD clone were significantly higher than those of the NT clone. Bioenergetically, the TFAM-KD clone expressed lower mOCR_B (p = 0.009) but higher ECAR_B (p = 0.037) than did the NT clone. We conclude that a reduction of mtDNA copy number and decrease of respiratory function of mitochondria in RCC might be compensated for by an increase of enzymes and factors that are involved in the upregulation of glycolysis to confer RCC more invasive and a drug-resistant phenotype in vitro.

Iron depletion enhances the effect of sorafenib in hepatocarcinoma

ABSTACT Human hepatocellular carcinoma (HCC) is known to have a poor prognosis. Sorafenib, a molecular targeted drug, is most commonly used for HCC treatment. However, its effect on HCC is limited in clinical use and therefore new strategies regarding sorafenib treatment are required. Iron overload is known to be associated with progression of chronic hepatitis and increased risk of HCC. We previously reported that iron depletion inhibited cancer cell proliferation and conversely induced angiogenesis. Indeed iron depletion therapy including iron chelator needs to be combined with anti-angiogenic drug for its anti-cancer effect. Since sorafenib has an anti-angiogenic effect by its inhibitory targeting VEGFR, we hypothesized that sorafenib could complement the anti-cancer effect of iron depletion. We retrospectively analyzed the relationship between the efficacy of sorafenib and serum iron-related markers in clinical HCC patients. In clinical cases, overall survival was prolonged in total iron binding capacity (TIBC) high- and ferritin low-patients. This result suggested that the low iron-pooled patients, who could have a potential of more angiogenic properties in/around HCC tumors, could be adequate for sorafenib treatment. We determined the effect of sorafenib (Nexavar®) and/or deferasirox (EXJADE®) on cancer cell viability, and on cell signaling of human hepatocarcinoma HepG2 and HLE cells. Both iron depletion by deferasirox and sorafenib revealed insufficient cytotoxic effect by each monotherapy, however, on the basis of increased angiogenesis by iron depletion, the addition of deferasirox enhanced anti-proliferative effect of sorafenib. Deferasirox was confirmed to increase vascular endothelial growth factor (VEGF) secretion into cellular supernatants by ELISA analysis. In in vivo study sorafenib combined with deferasirox also enhanced sorafenib-induced apoptosis. These results suggested that sorafenib combined with deferasirox could be a novel combination chemotherapy for HCC.

CRM1 inhibitor S109 suppresses cell proliferation and induces cell cycle arrest in renal cancer cells

Abnormal localization of tumor suppressor proteins is a common feature of renal cancer. Nuclear export of these tumor suppressor proteins is mediated by chromosome region maintenance-1 (CRM1). Here, we investigated the antitumor eff ects of a novel reversible inhibitor of CRM1 on renal cancer cells. We found that S109 inhibits the CRM1-mediated nuclear export of RanBP1 and reduces protein levels of CRM1. Furthermore, the inhibitory eff ect of S109 on CRM1 is reversible. Our data demonstrated that S109 signifi cantly inhibits proliferation and colony formation of renal cancer cells. Cell cycle assay showed that S109 induced G1-phase arrest, followed by the reduction of Cyclin D1 and increased expression of p53 and p21. We also found that S109 induces nuclear accumulation of tumor suppressor proteins, Foxo1 and p27. Most importantly, mutation of CRM1 at Cys528 position abolished the eff ects of S109. Taken together, our results indicate that CRM1 is a therapeutic target in renal cancer and the novel reversible CRM1 inhibitor S109 can act as a promising candidate for renal cancer therapy.

The cpk model of recessive PKD shows glutamine dependence associated with the production of the oncometabolite 2-hydroxyglutarate

Since polycystic kidney disease (PKD) was first noted over 30 years ago to have neoplastic parallels, there has been a resurgent interest in elucidating neoplasia-relevant pathways in PKD. Taking a nontargeted metabolomics approach in the B6(Cg)-Cys1(cpk/)J (cpk) mouse model of recessive PKD, we have now characterized metabolic reprogramming in these tissues, leading to a glutamine-dependent TCA cycle shunt toward total 2-hydroxyglutarate (2-HG) production in cpk compared with B6 wild-type kidney tissue. After confirmation of increased 2-HG expression in immortalized collecting duct cpk cells as well as in human autosomal recessive PKD tissue using targeted analysis, we show that the increase in 2-HG is likely due to glutamine-sourced α-ketoglutarate. In addition, cpk cells require exogenous glutamine for growth such that inhibition of glutaminase-1 decreases cell viability as well as proliferation. This study is a demonstration of the striking parallels between recessive PKD and cancer metabolism. Our data, once confirmed in other PKD models, suggest that future therapeutic approaches targeting this pathway, such as using glutaminase inhibitors, have the potential to open novel treatment options for renal cystic disease.

Grade-Dependent Metabolic Reprogramming in Kidney Cancer Revealed by Combined Proteomics and Metabolomics Analysis

Kidney cancer [or renal cell carcinoma (RCC)] is known as "the internist's tumor" because it has protean systemic manifestations, suggesting that it utilizes complex, nonphysiologic metabolic pathways. Given the increasing incidence of this cancer and its lack of effective therapeutic targets, we undertook an extensive analysis of human RCC tissue employing combined grade-dependent proteomics and metabolomics analysis to determine how metabolic reprogramming occurring in this disease allows it to escape available therapeutic approaches. After validation experiments in RCC cell lines that were wild-type or mutant for the Von Hippel-Lindau tumor suppressor, in characterizing higher-grade tumors, we found that the Warburg effect is relatively more prominent at the expense of the tricarboxylic acid cycle and oxidative metabolism in general. Further, we found that the glutamine metabolism pathway acts to inhibit reactive oxygen species, as evidenced by an upregulated glutathione pathway, whereas the β-oxidation pathway is inhibited, leading to increased fatty acylcarnitines. In support of findings from previous urine metabolomics analyses, we also documented tryptophan catabolism associated with immune suppression, which was highly represented in RCC compared with other metabolic pathways. Together, our results offer a rationale to evaluate novel antimetabolic treatment strategies being developed in other disease settings as therapeutic strategies in RCC.

Specific inhibition of the nuclear exporter exportin-1 attenuates kidney cancer growth

PURPOSE

Despite the advent of FDA-approved therapeutics to a limited number of available targets (kinases and mTOR), PFS of kidney cancer (RCC) has been extended only one to two years due to the development of drug resistance. Here, we evaluate a novel therapeutic for RCC which targets the exportin-1 (XPO1) inhibitor.

MATERIALS AND METHODS

RCC cells were treated with the orally available XPO1 inhibitor, KPT-330, and cell viability and Annexin V (apoptosis) assays, and cell cycle analyses were performed to evaluate the efficacy of KPT-330 in two RCC cell lines. Immunoblotting and immunofluorescence analysis were performed to validate mechanisms of XPO1 inhibition. The efficacy and on-target effects of KPT-330 were further analyzed in vivo in RCC xenograft mice, and KPT-330-resistant cells were established to evaluate potential mechanisms of KPT-330 resistance.

RESULTS

KPT-330 attenuated RCC viability through growth inhibition and apoptosis induction both in vitro and in vivo, a process in which increased nuclear localization of p21 by XPO1 inhibition played a major role. In addition, KPT-330 resistant cells remained sensitive to the currently approved for RCC multi-kinase inhibitors (sunitinib, sorafenib) and mTOR inhibitors (everolimus, temsirolimus), suggesting that these targeted therapeutics would remain useful as second line therapeutics following KPT-330 treatment.

CONCLUSION

The orally-available XPO1 inhibitor, KPT-330, represents a novel target for RCC whose in vivo efficacy approaches that of sunitinib. In addition, cells resistant to KPT-330 retain their ability to respond to available RCC therapeutics suggesting a novel approach for treatment in KPT-330-naïve as well as -resistant RCC patients.

Novel inhibitors of nuclear transport cause cell cycle arrest and decrease cyst growth in ADPKD associated with decreased CDK4 levels

Autosomal-dominant polycystic kidney disease (ADPKD) is a progressive, proliferative renal disease. Kidneys from ADPKD patients are characterized by the presence of cysts that are marked by enhanced proliferation and apoptosis of renal tubular epithelial cells. Current treatment of this disease is supportive, as there are few if any clinically validated targeted therapeutics. Given the parallels between cystic disease and cancer, and in light of our findings of the efficacy of the nuclear transport inhibitors in kidney cancer, which has similarities to ADPKD, we asked whether such inhibitors show utility in ADPKD. In this study, we tested selective inhibitors of nuclear export (SINE) in two human ADPKD cell lines and in an in vivo mouse model of ADPKD. After effective downregulation of a nuclear exporter, exportin 1 (XPO1), with KPT-330, both cell lines showed dose-dependent inhibition of cell proliferation through G₀/G₁ arrest associated with downregulation of CDK4, with minimal apoptosis. To analyze mechanisms of CDK4 decrease by XPO1 inhibition, localization of various XPO1 target proteins was examined, and C/EBPβ was found to be localized in the nucleus by XPO1 inhibition, resulting in an increase of C/EBPα, which activates degradation of CDK4. Furthermore, inhibition of XPO1 with the parallel inhibitor KPT-335 attenuated cyst growth in vivo in the PKD1 mutant mouse model Pkd1(v/v). Thus, inhibition of nuclear export by KPT-330, which has shown no adverse effects in renal serum chemistries and urinalyses in animal models, and which is already in phase 1 trials for cancers, will be rapidly translatable to human ADPKD.

Biological evaluation of a novel sorafenib analogue, t-CUPM

Sorafenib (Nexavar®) is currently the only FDA-approved small molecule targeted therapy for advanced hepatocellular carcinoma. The use of structural analogues and derivatives of sorafenib has enabled the elucidation of critical targets and mechanism(s) of cell death for human cancer lines. We previously performed a structure-activity relationship study on a series of sorafenib analogues designed to investigate the inhibition overlap between the major targets of sorafenib Raf-1 kinase and VEGFR-2, and an enzyme shown to be a potent off-target of sorafenib, soluble epoxide hydrolase. In the current work, we present the biological data on our lead sorafenib analogue, t-CUPM, demonstrating that this analogue retains cytotoxicity similar to sorafenib in various human cancer cell lines and strongly inhibits growth in the NCI-60 cell line panel. Co-treatment with the pan-caspase inhibitor, Z-VAD-FMK, failed to rescue the cell viability responses of both sorafenib and t-CUPM, and immunofluorescence microscopy shows similar mitochondrial depolarization and apoptosis-inducing factor release for both compounds. These data suggest that both compounds induce a similar mechanism of caspase-independent apoptosis in hepatoma cells. In addition, t-CUPM displays anti-proliferative effects comparable to sorafenib as seen by a halt in G0/G1 in cell cycle progression. The structural difference between sorafenib and t-CUPM significantly reduces inhibitory spectrum of kinases by this analogue, and pharmacokinetic characterization demonstrates a 20-fold better oral bioavailability of t-CUPM than sorafenib in mice. Thus, t-CUPM may have the potential to reduce the adverse events observed from the multikinase inhibitory properties and the large dosing regimens of sorafenib.

Novel sorafenib-based structural analogues: in-vitro anticancer evaluation of t-MTUCB and t-AUCMB

In the current work, we carried out a mechanistic study on the cytotoxicity of two compounds, trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-N-methyl-benzamide (t-AUCMB) and trans-N-methyl-4-{4-[3-(4-trifluoromethoxy-phenyl)-ureido]-cyclohexyloxy}-benzamide (t-MTUCB), that are structurally similar to sorafenib. These compounds show strong cytotoxic responses in various cancer cell lines, despite significant differences in the induction of apoptotic events such as caspase activation and lactate dehydrogenase release in hepatoma cells. Both compounds induce autophagosome formation and LC3I cleavage, but there was little observable effect on mTORC1 or the downstream targets, S6K1 and 4E-binding protein. In addition, there was an increase in the activity of upstream signaling through the IRS1/PI3K/Akt-signaling pathway, suggesting that, unlike sorafenib, both compounds induce mammalian target of rapamycin (mTOR)-independent autophagy. The autophagy observed correlates with mitochondrial membrane depolarization, apoptosis-inducing factor release, and oxidative stress-induced glutathione depletion. However, there were no observable changes in the endoplasmic reticulum-stress markers such as binding immunoglobulin protein, inositol-requiring enzyme-α, phosphorylated eukaryotic initiation factor 2, and the lipid peroxidation marker, 4-hydroxynonenal, suggesting endoplasmic reticulum-independent oxidative stress. Finally, these compounds do not have the multikinase inhibitory activity of sorafenib, which may be reflected in their difference in the ability to halt cell cycle progression compared with sorafenib. Our findings indicate that both compounds have anticancer effects comparable with sorafenib in multiple cell lines, but they induce significant differences in apoptotic responses and appear to induce mTOR-independent autophagy. t-AUCMB and t-MTUCB represent novel chemical probes that are capable of inducing mTOR-independent autophagy and apoptosis to differing degrees, and may thus be potential tools for further understanding the link between these two cellular stress responses.

Selective inhibitors of nuclear export (SINE)--a novel class of anti-cancer agents

Dysregulation of the nucleo-cytoplasmic transport of proteins plays an important role in carcinogenesis. The nuclear export of proteins depends on the activity of transport proteins, exportins. Exportins belong to the karyopherin β superfamily. Exportin-1 (XPO1), also known as chromosomal region maintenance 1 (CRM1), mediates transport of around 220 proteins. In this review, we summarized the development of a new class of antitumor drugs, collectively known as selective inhibitors of nuclear export (SINE). KPT-330 (selinexor) as an oral agent is showing activities in early clinical trials in both solid tumors and hematological malignancies.

Synergistic tumor suppression by combined inhibition of telomerase and CDKN1A

Tumor suppressor p53 plays an important role in mediating growth inhibition upon telomere dysfunction. Here, we show that loss of the p53 target gene cyclin-dependent kinase inhibitor 1A (CDKN1A, also known as p21(WAF1/CIP1)) increases apoptosis induction following telomerase inhibition in a variety of cancer cell lines and mouse xenografts. This effect is highly specific to p21, as loss of other checkpoint proteins and CDK inhibitors did not affect apoptosis. In telomerase, inhibited cell loss of p21 leads to E2F1- and p53-mediated transcriptional activation of p53-upregulated modulator of apoptosis, resulting in increased apoptosis. Combined genetic or pharmacological inhibition of telomerase and p21 synergistically suppresses tumor growth. Furthermore, we demonstrate that simultaneous inhibition of telomerase and p21 also suppresses growth of tumors containing mutant p53 following pharmacological restoration of p53 activity. Collectively, our results establish that inactivation of p21 leads to increased apoptosis upon telomerase inhibition and thus identify a genetic vulnerability that can be exploited to treat many human cancers containing either wild-type or mutant p53.

Neoadjuvant sorafenib treatment of clear cell renal cell carcinoma and release of circulating tumor fragments

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is characterized by high constitutive vascular endothelial growth factor A (VEGF-A) production that induces a specific vascular phenotype. We previously reported that this phenotype may allow shedding of multicellular tumor fragments into the circulation, possibly contributing to the development of metastasis. Disruption of this phenotype through inhibition of VEGF signaling may therefore result in reduced shedding of tumor fragments and improved prognosis. To test this hypothesis, we investigated the effect of neoadjuvant sorafenib treatment on tumor cluster shedding.

PATIENTS AND METHODS

Patients with renal cancer (n = 10, of which 8 have ccRCC) received sorafenib for 4 weeks before tumor nephrectomy. The resection specimens were perfused, and the perfundate was examined for the presence of tumor clusters. Effects of the treatment on the tumor morphology and overall survival were investigated (follow-up of 2 years) and compared with a carefully matched control group.

RESULTS

Neoadjuvant sorafenib treatment induced extensive ischemic tumor necrosis and, as expected, destroyed the characteristic ccRCC vascular phenotype. In contrast to the expectation, vital groups of tumor cells with high proliferation indices were detected in postsurgical renal venous outflow in 75% of the cases. Overall survival of patients receiving neoadjuvant treatment was reduced compared to a control group, matched with regard to prognostic parameters.

CONCLUSIONS

These results suggest that neoadjuvant sorafenib therapy for ccRCC does not prevent shedding of tumor fragments. Although this is a nonrandomized study with a small patient group, our results suggest that neoadjuvant treatment may worsen survival through as yet undefined mechanisms.

Synergistic interaction between the HDAC inhibitor, MPT0E028, and sorafenib in liver cancer cells in vitro and in vivo

PURPOSE

To investigate the antitumor activities of a histone deacetylase (HDAC) inhibitor, MPT0E028, plus sorafenib in liver cancer cells in vitro and in vivo.

EXPERIMENTAL DESIGN

Different liver cancer cell lines were exposed to sorafenib in the presence or absence of MPT0E028, and cell viability was determined by MTT assay. Effects of combined treatment on cell cycle and intracellular signaling pathways were assessed by flow cytometry and Western blot analysis. The Hep3B xenograft model was used to examine the antitumor activity in vivo.

RESULTS

Our data indicate that sorafenib and MPT0E028 synergistically reduced cell viability in liver cancer cells, and also markedly induced apoptotic cell death in these cells, as evidenced by the cleavage of caspase-3, PARP, and DNA fragmentation. MPT0E028 altered the global modifications of histone and nonhistone proteins regardless of the presence of sorafenib. However, sorafenib blocked MPT0E028-induced Erk activation and its downstream signaling cascades, such as Stat3 phosphorylation (Ser(727)) and Mcl-1 upregulation. Ectopic expression of constitutively active Mek successively reversed the apoptosis triggered by the combined treatment. Pharmacologic inhibition of Mek by PD98059 potentiated MPT0E028-induced apoptosis, suggesting that the synergistic interaction between MPT0E028 and sorafenib occurs at least partly through inhibition of Erk signaling. The data demonstrated that transcriptional activation of fibroblast growth factor receptor 3 (FGFR3) contributes to MPT0E028-mediated Erk phosphorylation. Finally, MPT0E028 plus sorafenib significantly improved the tumor growth delay (TGD) in a Hep3B xenograft model.

CONCLUSIONS

These findings suggest that MPT0E028 in combination with sorafenib has significant anti-hepatocellular carcinoma activity in preclinical models, potentially suggesting a novel therapeutic strategy for patients with advanced hepatocellular carcinoma.

Inhibition of PPARα induces cell cycle arrest and apoptosis, and synergizes with glycolysis inhibition in kidney cancer cells

Renal cell carcinoma (RCC) is the sixth most common cancer in the US. While RCC is highly metastatic, there are few therapeutics options available for patients with metastatic RCC, and progression-free survival of patients even with the newest targeted therapeutics is only up to two years. Thus, novel therapeutic targets for this disease are desperately needed. Based on our previous metabolomics studies showing alteration of peroxisome proliferator-activated receptor α (PPARα) related events in both RCC patient and xenograft mice materials, this pathway was further examined in the current study in the setting of RCC. PPARα is a nuclear receptor protein that functions as a transcription factor for genes including those encoding enzymes involved in energy metabolism; while PPARα has been reported to regulate tumor growth in several cancers, it has not been evaluated in RCC. A specific PPARα antagonist, GW6471, induced both apoptosis and cell cycle arrest at G0/G1 in VHL(+) and VHL(-) RCC cell lines (786-O and Caki-1) associated with attenuation of the cell cycle regulatory proteins c-Myc, Cyclin D1, and CDK4; this data was confirmed as specific to PPARα antagonism by siRNA methods. Interestingly, when glycolysis was blocked by several methods, the cytotoxicity of GW6471 was synergistically increased, suggesting a switch to fatty acid oxidation from glycolysis and providing an entirely novel therapeutic approach for RCC.

CRM1 blockade by selective inhibitors of nuclear export attenuates kidney cancer growth

PURPOSE

Renal cell carcinoma often presents asymptomatically and patients are commonly diagnosed at the metastatic stage, when treatment options are limited and survival is poor. Since progression-free survival using current therapy for metastatic renal cell carcinoma is only 1 to 2 years and existing drugs are associated with a high resistance rate, new pharmacological targets are needed. We identified and evaluated the nuclear exporter protein CRM1 as a novel potential therapy for renal cell carcinoma.

MATERIALS AND METHODS

We tested the efficacy of the CRM1 inhibitors KPT-185 and 251 in several renal cell carcinoma cell lines and in a renal cell carcinoma xenograft model. Apoptosis and cell cycle arrest were quantified and localization of p53 family proteins was assessed using standard techniques.

RESULTS

KPT-185 attenuated CRM1 and showed increased cytotoxicity in renal cell carcinoma cells in vitro with evidence of increased apoptosis as well as cell cycle arrest. KPT-185 caused p53 and p21 to remain primarily in the nucleus in all renal cell carcinoma cell lines, suggesting that the mechanism of action of these compounds depends on tumor suppressor protein localization. Furthermore, when administered orally in a high grade renal cell carcinoma xenograft model, the bioavailable CRM1 inhibitor KPT-251 significantly inhibited tumor growth in vivo with the expected on target effects and no obvious toxicity.

CONCLUSIONS

The CRM1 inhibitor protein family is a novel therapeutic target for renal cell carcinoma that deserves further intensive investigation for this and other urological malignancies.

From a multipotent stilbene to soluble epoxide hydrolase inhibitors with antiproliferative properties

Inspired by nature: Natural product isopropylstilbene was identified as an inhibitor of soluble epoxide hydrolase exhibiting antiproliferative properties. Following the natural product inspired design approach, a library of (E)-styryl-1H-benzo[d]imidazoles was synthesized and evaluated with recombinant enzyme and on several cancer cell lines.

Potential biofluid markers and treatment targets for renal cell carcinoma

Renal cell carcinoma (RCC) is the 13th most common cancer in the world and one of the few cancers for which incidence is increasing. This disease is generally asymptomatic at an early stage and is highly metastatic. Frequently discovered by physicians in the process of working up other diseases such as acute kidney injury, RCC is often discovered in an advanced form and many patients have metastases at the time of diagnosis. Given that life expectancy with currently approved therapies for metastatic RCC is approximately 1-2 years, biomarkers for RCC that will enable early detection are urgently needed. Although it is unlikely that highly sensitive and specific biomarkers will be identified in the near future that are useful for screening the general population, a noninvasive marker or set of markers could soon be used in general medicine, nephrology, and urology clinics to screen patients at increased risk of RCC. In addition to the ongoing need for RCC biomarkers, the frequent resistance reported with currently available targeted therapies makes the identification of new therapeutic targets similarly important. Many promising leads for new targeted therapies have come to light; some of these therapies are in clinical trials and others are still being evaluated in the laboratory.

A novel p21 attenuator which is structurally related to sorafenib

p21 is a member of the cyclin kinase inhibitor family of proteins and plays pivotal roles in cellular proliferation as well as in the regulation of apoptosis, and thus has diverse functions in diseases as varied as cancer and atherosclerosis. In light of its pleiotropic effects and potential clinical relevance, new methods of attenuation of p21 protein levels by selective inhibitors are therefore powerful tools to probe malignant, infectious and other diseases. Here we introduce a novel p21 attenuator, UC2288, which possesses consistent and relatively selective activity for p21. UC2288 was synthesized based on the chemical model of sorafenib, a multikinase inhibitor that also attenuates p21, but unlike sorafenib, UC2288 did not inhibit Raf kinases or alter p-ERK protein levels. UC2288 decreased p21 mRNA expression independently of p53, and attenuated p21 protein levels with minimal effect on p21 protein stability. In addition, UC2288 inhibits cell growth in the kidney cancer cell lines (GI50 = approximately 10 µM) as well as multiple other cancer cell lines. Thus, this novel p21 inhibitor will be indispensable for exploring the function of p21, and upon further study may be translatable to the clinic.

Impact of soluble epoxide hydrolase and epoxyeicosanoids on human health

The presence of epoxyeicosatrienoic acids (EETs) in tissues and their metabolism by soluble epoxide hydrolase (sEH) to 1,2-diols were first reported 30 years ago. However, appreciation of their importance in cell biology and physiology has greatly accelerated over the past decade with the discovery of metabolically stable inhibitors of sEH, the commercial availability of EETs, and the development of analytical methods for the quantification of EETs and their diols. Numerous roles of EETs in regulatory biology now are clear, and the value of sEH inhibition in various animal models of disease has been demonstrated. Here, we review these results and discuss how the pharmacological stabilization of EETs and other natural epoxy-fatty acids could lead to possible disease therapies.

Synergistic growth inhibition by sorafenib and vitamin K2 in human hepatocellular carcinoma cells

OBJECTIVE

Sorafenib is an oral multikinase inhibitor that has been proven effective as a single-agent therapy in hepatocellular carcinoma, and there is a strong rationale for investigating its use in combination with other agents. Vitamin K2 is nearly non-toxic to humans and has been shown to inhibit the growth of hepatocellular carcinoma. In this study, we evaluated the effects of a combination of sorafenib and vitamin K2 on the growth of hepatocellular carcinoma cells.

METHODS

Flow cytometry, 3-(4,5-dimethyl-2-thiazolyl-2,5-diphenyl-2H-tetrazolium bromide) and nude mouse xenograft assays were used to examine the effects of sorafenib and vitamin K2 on the growth of hepatocellular carcinoma cells. Western blotting was used to elucidate the possible mechanisms underlying these effects.

RESULTS

Assays for 3-(4,5-dimethyl-2-thiazolyl-2,5-diphenyl-2H-tetrazolium bromide) revealed a strong synergistic growth-inhibitory effect between sorafenib and vitamin K2. Flow cytometry showed an increase in cell cycle arrest and apoptosis after treatment with a combination of these two drugs at low concentrations. Sorafenib-mediated inhibition of extracellular signal-regulated kinase phosphorylation was promoted by vitamin K2, and downregulation of Mcl-1, which is required for sorafenib-induced apoptosis, was observed after combined treatment. Vitamin K2 also attenuated the downregulation of p21 expression induced by sorafenib, which may represent the mechanism by which vitamin K2 promotes the inhibitory effects of sorafenib on cell proliferation. Moreover, the combination of sorafenib and vitamin K2 significantly inhibited the growth of hepatocellular carcinoma xenografts in nude mice.

CONCLUSIONS

Our results determined that combined treatment with sorafenib and vitamin K2 can work synergistically to inhibit the growth of hepatocellular carcinoma cells. This finding raises the possibility that this combined treatment strategy might be promising as a new therapy against hepatocellular carcinoma, especially for patients with poor liver tolerance.

Kidney tumor biomarkers revealed by simultaneous multiple matrix metabolomics analysis

Metabolomics is increasingly being used in cancer biology for biomarker discovery and identification of potential novel therapeutic targets. However, a systematic metabolomics study of multiple biofluids to determine their interrelationships and to describe their use as tumor proxies is lacking. Using a mouse xenograft model of kidney cancer, characterized by subcapsular implantation of Caki-1 clear cell human kidney cancer cells, we examined tissue, serum, and urine all obtained simultaneously at baseline (urine) and at, or close to, animal sacrifice (urine, tissue, and plasma). Uniform metabolomics analysis of all three "matrices" was accomplished using gas chromatography- and liquid chromatography-mass spectrometry. Of all the metabolites identified (267 in tissue, 246 in serum, and 267 in urine), 89 were detected in all 3 matrices, and the majority was altered in the same direction. Heat maps of individual metabolites showed that alterations in serum were more closely related to tissue than was urine. Two metabolites, cinnamoylglycine and nicotinamide, were concordantly and significantly (when corrected for multiple testing) altered in tissue and serum, and cysteine-glutathione disulfide showed the highest change (232.4-fold in tissue) of any metabolite. On the basis of these and other considerations, three pathways were chosen for biologic validation of the metabolomic data, resulting in potential therapeutic target identification. These data show that serum metabolomics analysis is a more accurate proxy for tissue changes than urine and that tryptophan degradation (yielding anti-inflammatory metabolites) is highly represented in renal cell carcinoma, and support the concept that PPAR-α antagonism may be a potential therapeutic approach for this disease.

Celecoxib synergizes human pancreatic ductal adenocarcinoma cells to sorafenib-induced growth inhibition

BACKGROUND

Pancreatic ductal adenocarcinoma is frequently associated with aberrant activation of the Ras/Raf/MAPK pathway and cyclooxygenase-2 (COX-2) overexpression. This study evaluated the potential for combining the multikinase inhibitor sorafenib and the specific COX-2 inhibitor celecoxib as therapy in pancreatic ductal adenocarcinoma cells.

METHODS

BxPC-3, MIAPaCa-2, PANC-1 and AsPC-1 pancreatic adenocarcinoma cells were exposed to sorafenib and celecoxib combined treatment in vitro. Cell viability and various growth promoting and survival signaling pathways were monitored by MTT, flow cytometry and Western blotting.

RESULTS

Combined treatment with sorafenib and celecoxib synergistically inhibited pancreatic adenocarcinoma cell proliferation. This regimen produced combination index (CI) values between 0.67 and 0.92 for the various cell lines, indicating significant synergistic interactions between sorafenib and celecoxib, which also markedly inhibited the migratory capacity. The growth inhibition was associated with an accumulation of cells in the G(0)/G(1) phase of the cell cycle and induction of apoptosis. These changes were accompanied by a significant reduction of p21(WAF1/Cip1) levels, where celecoxib sensitized the cells to sorafenib-mediated p21(WAF1/Cip1) suppression.

CONCLUSION

These results suggest that combined treatment with sorafenib and celecoxib synergistically induce growth inhibition and apoptosis in pancreatic adenocarcinoma cells through a process involving p21(WAF1/Cip1) suppression.