Metabolic pathway analyses identify proline biosynthesis pathway as a promoter of liver tumorigenesis

BACKGROUND & AIM

Under the regulation of various oncogenic pathways, cancer cells undergo adaptive metabolic programming to maintain specific metabolic states that support their uncontrolled proliferation. As it has been difficult to directly and effectively inhibit oncogenic signaling cascades with pharmaceutical compounds, focusing on the downstream metabolic pathways that enable indefinite growth may provide therapeutic opportunities. Thus, we sought to characterize metabolic changes in hepatocellular carcinoma (HCC) development and identify metabolic targets required for tumorigenesis.

METHODS

We compared gene expression profiles of Morris Hepatoma (MH3924a) and DEN (diethylnitrosamine)-induced HCC models to those of liver tissues from normal and rapidly regenerating liver models, and performed gain- and loss-of-function studies of the identified gene targets for their roles in cancer cell proliferation in vitro and in vivo.

RESULTS

The proline biosynthetic enzyme PYCR1 (pyrroline-5-carboxylate reductase 1) was identified as one of the most upregulated genes in the HCC models. Knockdown of PYCR1 potently reduced cell proliferation of multiple HCC cell lines in vitro and tumor growth in vivo. Conversely, overexpression of PYCR1 enhanced the proliferation of the HCC cell lines. Importantly, PYCR1 expression was not elevated in the regenerating liver, and KD or overexpression of PYCR1 had no effect on proliferation of non-cancerous cells. Besides PYCR1, we found that additional proline biosynthetic enzymes, such as ALDH18A1, were upregulated in HCC models and also regulated HCC cell proliferation. Clinical data demonstrated that PYCR1 expression was increased in HCC, correlated with tumor grade, and was an independent predictor of clinical outcome.

CONCLUSION

Enhanced expression of proline biosynthetic enzymes promotes HCC cell proliferation. Inhibition of PYCR1 or ALDH18A1 may be a novel therapeutic strategy to target HCC.

LAY SUMMARY

Even with the recently approved immunotherapies against liver cancer, currently available medications show limited clinical benefits or efficacy in the majority of patients. As such, it remains a top priority to discover new targets for effective liver cancer treatment. Here, we identify a critical role for the proline biosynthetic pathway in liver cancer development, and demonstrate that targeting key proteins in the pathway, namely PYCR1 and ALDH18A1, may be a novel therapeutic strategy for liver cancer.

Abstract A115: Mechanisms of resistance toward the FGFR inhibitor rogaratinib in preclinical urothelial bladder cancer models

Introduction: Approximately one in three cases of urothelial bladder carcinoma (UBC) shows high expression of fibroblast growth factor receptor (FGFR) genes, predominantly of FGFR3 and FGFR1. The antitumor activity of the small molecule pan-FGFR-inhibitor rogaratinib (BAY1163877) has been demonstrated in preclinical models1, and the drug is currently being investigated in phase II and III clinical trials. However, clinical experience suggests the emergence of resistance with single-agent therapy. Here, we investigated the changes that occur with long-term FGFR inhibition and the development of resistance in preclinical UBC models, in order to identify possible combination strategies. Methods: We generated 13 resistant cell lines from the rogaratinib-sensitive cell lines JMSU1, RT112, RT4, and SW780, through continuous culture with various, increasing concentrations of rogaratinib. Transcriptomic and proteomic characterization was performed to identify potential therapeutic targets, of which a subset was evaluated using in vitro drug testing. We furthermore generated an in vivo resistant model by repeatedly transplanting JMSU1-derived xenografts. Results: Rogaratinib resistance developed reproducibly in vitro within several months and up to one year. We confirmed the lack of rogaratinib response in proliferation and viability assays. Transcriptomic analysis of resistant cell lines revealed changes in gene expression, with 300 to 2000 differentially expressed genes per sub-line (2-fold, p-adj. = 0.01). Hallmark gene sets such as MYC targets, epithelial-mesenchymal transition, or KRAS signaling were either negatively or positively correlated with resistance, but there was no single pathway change common to all cell lines. Genomic analysis found no mutations of the original driver FGFR genes and only few mutations in other receptor tyrosine kinase (RTK), MAPK, or PI3K signaling pathways. Proteomic analysis revealed activation of other RTKs in the rogaratinib-resistant models compared with the parental, rogaratinib-sensitive cells. These included EGFR, ErbB3, and MET, for which clinically approved inhibitors are available. We tested these as single-agents and in combination with rogaratinib in resistant cell lines to delineate potentially synergistic combinations. The JMSU1 in vivo resistance model confirmed the in vitro observations, where MET was upregulated upon resistance. The best anti-tumor efficacy was achieved with combined FGFR- and MET-inhibition, showing that FGFR signaling can remain a relevant oncogenic driver in addition to other RTKs activated as an escape mechanism. Conclusion: Continuous in vitro culture of cell lines with rogaratinib over several months led to resistance in all four evaluated models. Gene expression was considerably changed in these resistant cell lines, and proteomic analysis revealed activation of several RTKs. While the significance of many gene expression changes still remains to be determined, potent therapeutic targets were identified in several resistant cell lines, which point out opportunities for combination therapy. 1. Grunewald S, Politz O, Bender S, et al. Rogaratinib: A potent and selective pan-FGFR inhibitor with broad antitumor activity in FGFR-overexpressing preclinical cancer models. Int J Cancer. 2019.

Citation Format: Isabel S Jerchel, Atanas Kamburov, Sabine Zitzmann-Kolbe, Ralf Lesche, Alexander Walter, Dominik Mumberg, Oliver Politz, Sylvia Gruenewald. Mechanisms of resistance toward the FGFR inhibitor rogaratinib in preclinical urothelial bladder cancer models [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr A115. doi:10.1158/1535-7163.TARG-19-A115

Abstract 3080: Activity of pan-FGFR inhibitor rogaratinib and PI3K inhibitor copanlisib in preclinical urothelial bladder cancer models

Rogaratinib is a potent small molecule pan-FGFR inhibitor that leads to downregulation of MAPK and PI3K signaling (1). In a recent Phase I study rogaratinib demonstrated higher ORR in locally advanced or metastatic urothelial bladder cancer (UBC) with FGFR mRNA overexpression in patients with PIK3CA and RASwildtype than in those harboring PIK3CA or RAS mutations (2). In UBC, about 25% of tumors contain mutated PIK3CA of which 75% represent hot spot mutations E545K or E542K (3). Copanlisib is a potent pan class I PI3K inhibitor with predominant activity against the α and δ isoforms being approved for treatment of relapsed follicular lymphoma (4). We evaluated the activity of rogaratinib in cellular and in vivo efficacy studies in bladder cancer models in monotherapy and in combination with copanlisib. Cell proliferation and viability in response to rogaratinib, copanlisib or the combination of both was studied in rogaratinib-sensitive UBC cell lines like RT112 as well as in a recombinant RT112-PIK3CAE545K cell line. Rogaratinib potently inhibited cell proliferation with IC50 values in the double nM range. Copanlisib’s potency varied between 20 and 900 nM. In combination, rogaratinib and copanlisib increased cell death and were synergistic as shown by their proliferation combination indices for the absolute IC50 and IC80. Expression of the PIK3CAE545K hot spot mutant in RT112 cells decreased the anti-proliferative efficacy of rogaratinib but did not change the sensitivity to copanlisib. In vivo, rogaratinib led to tumor regression in the FGFR1-expressing JMSU1 xenograft and strongly inhibited tumor growth in the FGFR3-driven RT112 model. Copanlisib did not show significant inhibition of tumor growth in monotherapy in either model. In the JMSU1 model the combination was not superior to rogaratinib alone at maximal tolerated doses. In the RT112 as well as in the RT112-PIK3CAE545K model, the combination significantly improved anti-tumor activity. In a PDX model with FGFR3 overexpression and a PIK3CAH1047R hot spot mutation rogaratinib did not inhibit tumor growth significantly while copanlisib displayed significant anti-tumor effects. The combination of both drugs reduced tumor growth compared to either monotherapy group. In conclusion, in UBC tumor models overexpressing FGFR with differing sensitivities to rogaratinib, its anti-tumor activity could be further enhanced when combined with copanlisib and suggests that PIK3CA mutations may play a role in reduced sensitivity of UBC to FGFR inhibition. These promising results warrant further development of rogaratinib in monotherapy and in combination. Clinical trials with rogaratinib are currently recruiting (NCT03517956, NCT03410693, NCT03473756).

References:

Jerchel et al. Cancer Res. 2018; 78: Abs. 4781.

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Citation Format: Isabel S. Jerchel, Pascale Lejeune, Rita Lampignano, Alexander Walter, Ralf Lesche, Atanas Kamburov, Dominik Mumberg, Peter Ellinghaus, Oliver Politz, Sylvia Gruenewald. Activity of pan-FGFR inhibitor rogaratinib and PI3K inhibitor copanlisib in preclinical urothelial bladder cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3080.

Abstract 3477: Metabolic pathway analyses identify proline biosynthesis as a promoter of liver carcinogenesis

Cancer cells undergo dramatic metabolic reprogramming, largely to meet the requirements of sustained proliferation. These metabolic pathways are tightly regulated by various oncogenes, such as Myc and Ras. However, it has been difficult to directly and effectively inhibit these oncogenic signaling cascades with pharmacological compounds. Therefore, focusing on the downstream metabolic pathways that enable indefinite growth may provide a therapeutic opportunity. To identify metabolic enzymes required for hepatocellular carcinoma (HCC) tumorigenesis, we compared gene expression profiles of normal liver tissue to the Morris Hepatoma and DEN (Diethylnitrosamine)-induced HCC models as well as a liver regeneration model. PYCR1 (Pyrroline-5-Carboxylate Reductase 1), an enzyme in the proline biosynthesis pathway, was identified as one of the top up-regulated genes in the HCC models. An increase in PYCR1 protein levels in tumor samples versus normal liver tissue was confirmed by Western blot. shRNA-mediated knockdown of PYCR1 in HCC cell lines (Huh-7, Hep3B, HepG2 SNU-398, and MH3924a) potently reduced cell proliferation in vitro and tumor growth in vivo. Conversely, overexpression of PYCR1 enhanced the proliferation of Hep3B and AML12 cells. Importantly, PYCR1 expression was not elevated in regenerating tissues, and knockdown in a non-tumorigenic cell line did not influence proliferation. Additional enzymes in the proline biosynthesis pathway were also altered in tumors. For instance, ALDH18A1 was up-regulated and knockdown by shRNA decreased proliferation of human HCC cell lines. Metabolomic analyses suggested that the metabolism of glucose was disrupted in PYCR1 knockdown cells, with reduced fluxes through glycolytic and pentose phosphate pathways. Clinical data demonstrated that PYCR1 expression was increased in HCC, and expression levels correlated with increasing tumor grades and were independent predictors of clinical outcome. Overall, our data suggest that enhanced expression of proline biosynthetic enzymes promotes cell proliferation, and that inhibiting PYCR1 or ALDH18A1 may be a novel therapeutic strategy to target HCC.

Citation Format: Zhaobing Ding, Russell E. Ericksen, Michael Steckel, Andrea Haegebarth, Sylvia Gruenewald, Weiping Han. Metabolic pathway analyses identify proline biosynthesis as a promoter of liver carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3477.

Abstract 4779: Rogaratinib, a small molecule pan-FGFR inhibitor potently inhibits FGFR4-phosphorylation and exerts anti-tumor efficacy in vivo and in vitro

Fibroblast growth factor signaling plays an essential role in many physiological processes, including cell proliferation, survival, differentiation, migration, and apoptosis Over-activation of the pathway can lead to the development of various cancers. There are four different FGFR subtypes with over 20 ligands providing a very complex network of interactions and signaling.

FGFR4 plays an important role in normal physiology such as myogenesis muscle regeneration and bile acid synthesis Activating mutations in the kinase domain of FGFR4 have been shown to mediate cancer development, for example, breast cancer, hepatocellular carcinoma (HCC) or rhabdomyosarcoma.

Rogaratinib is a potent inhibitor of all FGFR subtypes with low nanomolar binding kinetics towards the four kinase domains. We explored the effect of rogaratinib on cell lines with high expression levels of FGFR4 mRNA, such as breast cancer cell line MDA-MB453 and rhabdomyosarcoma cell line SH30. We could show that the proliferation of these cell lines is potently inhibited by rogaratinib and accompanied with induction of apoptosis. The Mode-of-action analysis of rogaratinib activity in these cell lines showed inhibition of FGFR4-phosphorylation and downstream signaling at clinical relevant doses.

The in vitro efficacy of rogaratinib in FGFR4 dependent cell lines was further observed as in vivo efficacy in xenograft models of rhabdomyosarcoma and HCC.

Elevation of FGFR4 expression has been associated with resistance development in several cancer types such as breast cancer.

In line with the observed anti-tumor efficacy of rogartinib in vitro and in vivo in breast cancer, sarcoma and HCC models, RNA in situ hybridization by RNAscope, revealed high FGFR4 mRNA expression in TMA's from these tumor types..)

The combination of rogaratinib with standard-of-care provides further options for addressing resistance mechanisms mediated by elevated FGFR4 expression. In addition we have profiled a number of patient derived HCC xenograft models revealing the high efficacy of rogaratinib in models with elevated FGFR expression including FGFR4.

Citation Format: Oliver Politz, Sylvia Gruenewald, Alexander Walter, Franziska Siegel, Arne Scholz, Sebastian Bender, Christoph Kneip, Peter Ellinghaus. Rogaratinib, a small molecule pan-FGFR inhibitor potently inhibits FGFR4-phosphorylation and exerts anti-tumor efficacy in vivo and in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4779.

Abstract 4781: Changes in intracellular signaling following chronic FGFR inhibition in urothelial bladder cancer models

Preclinical and clinical studies have validated the therapeutic potential of FGFR inhibition in urothelial bladder cancer (UBC) patients with FGFR genetic aberrations. Rogaratinib is a potent small-molecule pan-FGFR inhibitor being studied in phase I trials in UBC. Here, we studied the effects of chronic exposure of bladder cancer cells in vitro to FGFR inhibition by rogaratinib to identify changes in signaling and gene expression patterns that may identify possible drug combinations that may enhance efficacy of rogaratinib and help overcome inherent and/or acquired treatment resistance. Cell proliferation in response to rogaratinib was evaluated using crystal violet staining in a panel of 13 UBC cell lines. Continuous culture of two cell lines–JMSU1 and RT112–with either constant or increasing concentrations of rogaratinib in several independent approaches generated the resistant sublines, JMSU1-R1 to -R4 and RT112-R1 to -R4. In both cellular models rogaratinib resistance (defined as >30-fold [JMSU1] or >100-fold [RT112] difference in absolute IC50 of sublines vs. parental lines) arose reproducibly and with various treatment schedules. Morphologic changes were also observed. Transcriptomic (RNAseq) and proteomic (R&D Systems proteome profiler arrays) analyses of these cell lines or rogaratinib-treated versus untreated parental cells, respectively, revealed changes that co-occur with the development of resistance. Analysis of the phospho-proteome showed increased phosphorylation of several receptor tyrosine kinases compared to the parental cell lines. Phosphorylation levels varied among the 4 resistant sublines that were derived from the same parental line. This resulted in alteration of downstream signaling pathways in rogaratinib-treated sublines compared to parental cell lines. In conclusion, exposure of selected bladder cancer cell lines to rogaratinib resulted in development of resistance and changes in FGFR signaling and gene expression pathways that may identify strategies to optimize treatment with FGFR inhibitors.

Citation Format: Isabel S. Jerchel, Atanas Kamburov, Ralf Lesche, Sabine Zitzmann-Kolbe, Alexander Walter, Peter Ellinghaus, Dominik Mumberg, Oliver Politz, Sylvia Gruenewald. Changes in intracellular signaling following chronic FGFR inhibition in urothelial bladder cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4781.

Abstract 4989: 3D spheroid screen yields SCD1 pathway inhibitors for the treatment of cancer

With three-dimensional growth conditions, multicellular tumor spheroids reproduce several parameters of the tumor microenvironment, including oxygen and nutrient gradients, characteristic of poorly vascularized tumor regions. 3D high content screening (HCS) identified compounds that selectively kill tumor cells in the inner core of tumor cell spheroids by targeting the Stearoyl CoA Desaturase 1 (SCD1) pathway. SCD1 catalyzes the rate-limiting step in the production of mono-unsaturated fatty acids (MUFAs). Cancer cells are dependent on higher levels of MUFAs compared to normal cells and SCD1 is highly expressed in multiple tumor types. Changes in the MUFA / SFA (saturated fatty acid) ratio alters lipid biosynthesis and thus triggers cellular (ER) stress and induces the Unfolded Protein Response. Although the lead compound was very effective in vitro, it had unfavorable PK and physical chemistry properties, including low permeability and solubility and very high lipophilicity. This led to insufficient oral bioavailability, which could be overcome by optimization of PK and physical chemistry properties. Here, we report on the in vitro/in vivo effects of our 3D HCS compounds which showed high potency in the 3D spheroid inner core death assay with T47D breast cancer cells. In this in vitro model compound-induced inner core cell death is enhanced by SCD1 substrates palmitic or stearic acid and rescued by the SCD1 products palmitoleic or oleic acid. Furthermore, the effects can be reproduced in 2D cultures, which become increasingly sensitive to inhibition by our 3D HCS compounds with decreasing FBS concentration in the culture medium and this effect can also be rescued by addition of MUFAs but not of palmitic acid. Mode of action analysis showed that our compounds reduced palmitoleoyl- or oleoyl-CoA levels and simultaneously increased saturated fatty acyl-CoAs of palmitate or stearate in several cell lines as well as in vivo. In the sensitive T47D cells, the compounds induced expression of stress response genes and genes related to lipid metabolism. While these results support the SCD1 pathway as target for our 3D HCS compounds, we also observed striking differences to published SCD1 inhibitors suggesting a new cancer target beyond SCD1. Thus, further validation of our inhibitors in vitro and in vivo will be required, but these results suggest that 3D spheroid cultures may be a valuable tool for elucidation of new drug targets for cancer therapy.

Citation Format: Sylvia Gruenewald, Carolyn Sperl, Patrick Steigemann, Alexander Walter, Sylvia Zacharias, Uwe Eberspaecher, Roland Neuhaus, Ludwig Zorn, Wolfgang Schwede, Kai Thede, Sven Christian. 3D spheroid screen yields SCD1 pathway inhibitors for the treatment of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4989. doi:10.1158/1538-7445.AM2017-4989

Abstract 1079: Preclinical activity of the FGFRinhibitor BAY 1163877 alone or in combination with antihormonal therapy in breast cancer

BAY 1163877 is an orally available, highly potent and selective pan fibroblast growth factor receptor (FGFR) inhibitor. In an ongoing Phase 1 clinical trial (NCT01976741) BAY 1163877 showed clinical responses at exceptional tolerability in patients suffering from different tumor types including urothelial bladder carcinoma or lung tumors, which were selected based on elevated FGFR1-3 mRNA expression. In the preclinical phase, the compound demonstrated significant single agent anti-tumor activity in various tumor models with different FGFR alterations leading to FGFR overexpression (e.g. FGFR gene amplifications or mutations). Genetic alterations of FGFRs can also be found in breast cancer with 7.5 - 17% of all tumors harboring a FGFR1 gene amplification. Elevated FGFR1 mRNA levels can be found in up to 22% of breast cancer cell lines as well as clinical samples. Other FGFR alterations include FGFR2 or FGFR4 gene amplifications as well as elevated FGFR mRNA levels, which were reported in all breast cancer subtypes. We therefore investigated BAY1163877 monotherapy in various breast cancer models. Due to the favorable clinical safety profile of BAY1163877, we also examined a combination treatment with early line antihormonal therapies in hormone receptor positive breast cancer.

In vitro profiling of BAY 1163877 in a number of breast cancer cell lines showed a clear association of efficacy with expression levels of different FGFR isoforms. The efficacy was further investigated in several patient- or cell line-derived breast cancer in vivo models. For instance, BAY 1163877 alone dosed 38mg/kg twice daily induced tumor growth inhibition of greater than 90% in a subcutaneous mouse syngeneic 4T1 breast cancer model expressing elevated levels of FGFR2.

Resistance to endocrine therapy appears associated with FGFR1 gene amplification and may explain the poor prognosis of FGFR1 overexpressing tumors treated with adjuvant tamoxifen. We therefore investigated the combination of the panFGFR-inhibitor BAY 1163877 with the clinically used antihormonal compound fulvestrant in selected luminal breast cancer PDX models. Some of these models showed resistance to antihormonal treatment in monotherapy but improved in vivo efficacy in combined treatment using BAY 1163877 and fulvestrant.

These data may warrant further clinical investigation of BAY1163877alone or in combination with antihormonal therapy in patients with FGFR overexpressing breast cancer.

Citation Format: Oliver Politz, Peter Ellinghaus, Sebastian Bender, Sylvia Gruenewald, Franziska Siegel, Marie-Pierre Collin, Sabine Zitzmann-Kolbe, Dominik Mumberg, Karl Ziegelbauer. Preclinical activity of the FGFRinhibitor BAY 1163877 alone or in combination with antihormonal therapy in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1079. doi:10.1158/1538-7445.AM2017-1079

Abstract 4332: Discovery of BAY 1163877 - A pan-FGFR inhibitor: De novo structure-based design and lead optimization of benzothiophenyl-pyrrolotriazines

Fibroblast growth factors (FGFs) orchestrate a variety of cellular functions by binding to their transmembrane tyrosine-kinase receptors (FGFR1-4) and activating downstream signaling pathways. Alterations in FGFR encoding genes are frequently observed in a variety of solid tumors including lung, gastric, breast and urothelial cancer. Therefore, targeting FGFRs using selective FGFR inhibitors is an attractive therapeutic approach to treat cancer patients.

BAY 1163877 is an orally active, highly potent and selective small molecule FGFR-1, -2 and -3 kinase inhibitor. We disclose for the very first time its discovery and chemical structure. BAY 1163877 was derived from a de novo structure-based design approach and medicinal chemistry optimization. Data on the structure activity relationship and the pharmacokinetic profile of the benzothiophenyl-pyrrolotriazine structure class will be presented. Based on its favorable preclinical profile, BAY 1163877 is currently being investigated in a Phase 1 clinical trial (NCT01976741).

Citation Format: Marie-Pierre L. Collin, Mario Lobell, Walter Huebsch, Dirk Brohm, Mélanie Héroult, Klemens Lustig, Sylvia Gruenewald, Ulf Boemer, Rolf Jautelat, Holger Hess-Stump, Stefan Jaroch, Michael Brands, Karl Ziegelbauer. Discovery of BAY 1163877 - A pan-FGFR inhibitor: De novo structure-based design and lead optimization of benzothiophenyl-pyrrolotriazines. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4332.

Abstract 1163: Phosphoserine aminotransferase 1 (PSAT1) as a novel anti-tumor target in hepatocellular carcinoma

With an estimated 700,000 new cases per year, hepatocellular carcinoma (HCC) represents the fifth commonest cancer and is the third leading cause of cancer death worldwide. Its 5-year survival rate after surgery is only 5-6%. Although HCC cases occur predominantly in the East and Southeast Asia and Sub-Saharan Africa, the incidence is rising in the West, largely due to an increasing incidence of Hepatitis C virus infection, alcoholic liver disease, and non-alcoholic steatohepatitis related to obesity and type II diabetes. Besides sorafenib, an oral multikinase inhibitor approved for the treatment of HCC, there is no other pharmacological agent in the treatment of HCC.

Cancer cells undergo dramatic metabolic reprogramming to sustain uncontrolled proliferation. Accumulating evidence supports abnormal metabolic pathways as an emerging hallmark of cancer. To identify metabolic genes required for HCC tumorigenesis, we compared gene expression profiles of a rat orthotopic and a mouse DEN (Diethylnitrosamine)-induced HCC model to a liver regeneration model and to normal liver by PCR arrays, transcriptomic analysis, and metabolomic profiling. Serine and glycine levels were increased in tumors of the HCC models as determined by NMR spectroscopy. PSAT1 (phosphoserine aminotransferase 1), an enzyme in the serine biosynthesis pathway, was identified as one of the top up-regulated genes in the HCC models. An increase in PSAT1 protein levels in tumor samples versus normal liver tissue was confirmed by Western blot. Knockdown of PSAT1 in rat hepatoma cells (MH3924a) led to a dramatic reduction in cell proliferation in vitro and in vivo. Moreover, a doxycycline-inducible knockdown approach confirmed the anti-proliferation effect of PSAT1 depletion. Interestingly, depletion of PSAT1 showed a variable effect on other HCC cells (e.g. Hep3B and Huh-7), suggesting the involvement of other genetic and metabolic factors. Detailed analysis of PSAT1 as a potential drug target for HCC is currently being addressed in in vivo studies.

Citation Format: Zhaobing Ding, Kenneth Wee, Eung-Sam Kim, Animesh Samanta, Michael Steckel, Marian Raschke, Sendhil Velan, Young-Tae Chang, Andrea Haegebarth, Karl Ziegelbauer, Sylvia Gruenewald, Weiping Han. Phosphoserine aminotransferase 1 (PSAT1) as a novel anti-tumor target in hepatocellular carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1163. doi:10.1158/1538-7445.AM2015-1163

Postural renal transplant obstruction: a case report and review of the literature

A 48-year-old woman underwent cadaveric renal transplantation for end-stage renal failure secondary to polycystic kidney disease. Nine months after transplantation, intermittent renal dysfunction and severe graft hydronephrosis developed despite the presence of a ureteric stent. A Tc-99m MAG3 scan performed with the patient standing showed complete transplant obstruction. Rapid tracer clearance with progressive bladder filling was present when the patient was imaged in the supine position. Ureteric obstruction is the most common urologic complication of renal transplantation. However, postural ureteric obstruction has been described only rarely. This case indicates that posture may affect ureteric patency and highlights this potential pitfall in the evaluation of intermittent graft dysfunction by diuretic renography.

Less pain does equal better quality of life following strontium-89 therapy for metastatic prostate cancer

93 patients with hormone refractory metastatic prostate cancer were entered on a prospective study to measure reduction in pain and changes in quality of life (QoL) after the administration of 150 MegaBequerel (MBq) Strontium-89 (Sr-89). QoL was assessed using a validated instrument, the Functional Living Index - Cancer (FLIC) questionnaire. Pain response was measured using the Radiation Therapy Oncology Group scoring system. Overall there was limited QoL improvement over 3 months following Sr-89. However, in the 53 patients (63%) achieving pain responses, QoL did significantly improve within 6 weeks of receiving Sr-89 compared to patients with stable or worsening bone pain, and this was independent of other parameters that might influence QoL outcomes, such as performance status, baseline PSA and extent of skeletal disease (P = 0.004). PSA 'response' occurred in 30 patients (37%) over 4 months after Sr-89. This did not appear to correlate with clinical improvement. This study supports the presumption that improvement in pain following Sr-89 is accompanied by better QoL. The lack of correlation of PSA response and clinical parameters indicates that in the palliative setting, PSA may not provide a useful surrogate for treatment outcome.

Early experience in the use of Levovist ultrasound contrast in the evaluation of liver masses

The aim of the present paper was to assess the utility of Levovist in defining the pathology of liver masses. Levovist is a new ultrasound contrast agent consisting of galactose microparticles, air bubbles and palmitic acid. Prospective studies were performed in patients referred for further evaluation of known liver masses. Levovist was peripherally injected and colour Doppler ultrasound studies were performed. Findings were correlated with clinicopathology and three other imaging modalities: biphasic spiral CT, CT arterial portography and contrast MRI. Twenty-five patients were studied (15 male and 10 female) in the age range 25-74 years. Liver masses ranged from 0.5 to 7 cm in maximum diameter. Thirteen lesions were benign and 12 were malignant (four hepatomas (HCC) and eight metastases). Levovist enhancement occurred in 18 lesions. Of these, six were benign (four focal nodular hyperplasias (FNH) and two haemangiomas). All 12 malignant lesions demonstrated enhancement. The HCC showed a mosaic pattern of central and peripheral enhancement, and the FNH demonstrated a spoke-wheel pattern. It was not possible to distinguish between haemangiomas and malignant lesions. Non-enhancing lesions may well be benign, with all malignancies showing some enhancement. Characteristic enhancement patterns were found for HCC (mosaic) and FNH (spoke-wheel). It was not possible to distinguish between metastases and benign lesions (haemangiomas) when the pattern of enhancement was peripheral.

Low-dose dopamine after kidney transplantation: assessment by Doppler ultrasound

Low-dose dopamine (LDD) is commonly used after kidney transplantation as a renoprotective agent, although the benefits of dopamine (DA) in this setting are controversial. LDD increases renal blood flow, decreases resistive index (RI) and causes diuresis in normal kidneys. We hypothesised that the vasculature of a denervated renal transplant may not respond to DA in the same way as healthy native kidneys. In a prospective, controlled study, renal blood flow velocity and vascular resistance were measured by Doppler ultrasound in recent kidney transplants (n = 20) over a range of DA doses (0-5 microg/kg/min). Main renal artery velocity was lower in kidneys with acute renal dysfunction than in those with normal function (0.60 +/- 0.31 vs. 0.81 +/- 0.24, respectively, p < 0.05). There was no demonstrable haemodynamic effect of LDD on either RI or main renal artery velocity as measured by Doppler ultrasound. Interestingly, the only significant correlation with mean RI was trough cyclosporin A level (r = 0.57, p < 0.001). Technical or timing factors cannot be used to explain the absence of DA effect, with equivalent doses capable of producing vasodilatation and reduced RI in studies of normal kidneys. In summary, these findings contrast the DA response of healthy native kidneys and may explain studies showing no clinical benefit of LDD in the early post-transplant period. These data suggest an insensitivity of recently implanted kidneys to the vasodilatory effects of LDD, that other factors such as cyclosporin A vasoconstriction may also be important, and question the rationale for routine LDD after kidney transplantation.

Life-threatening pica: liver abscess from perforating foreign body

A case is presented of a patient with a psychiatric illness and pica who developed a pyogenic liver abscess due to perforation of the duodenum by a pen. This report emphasizes the importance of ultrasound and computed tomography in making a rapid diagnosis. The relative superiority of ultrasound was revealed because an anaesthetic was not required for scanning, and in addition to the liver abscess, the precise location of the perforating foreign body was demonstrated.

Parallel hole collimator acceptance tests for SPECT and planar studies

Several methods of determining gamma-camera collimators hole alignment and integrity were compared. Four collimators were tested: two new cast collimators and two used foil collimators, one with damage to the protective surface. The most sensitive tests for collimator damage were found to be the collimated x-ray source, COR offset test and collimator hole alignment test.

Albendazole treatment of recurrent hydatid disease: serial evaluation with ultrasound

Four patients with complex abdominal hydatid cysts, one of whom also had pulmonary and pelvic involvement, were treated with up to six 28-day courses of albendazole 400 mg per oral twice daily. As part of a prospective study, serial ultrasound scanning was performed after each 28-day course of albendazole and showed evidence of remission of disease in all four patients. Transient minor abnormalities of liver function were noted during treatment. Ultrasound scanning showed the disappearance of daughter cysts and cystic septation, increase in echogenicity and marked reduction in cyst size. Consolidation of these changes and, in some cases, disappearance of the cysts, were noted with continued therapy. Albendazole seems to be a safe and effective agent in the treatment of recurrent hydatid disease, exerting most of its cysticidal activity within the first 2-3 months of therapy.

Risk of aortic aneurysm surgery as assessed by preoperative gated heart pool scan

Gated heart pool scan measuring left ventricular ejection fraction (LVEF) was performed preoperatively in 72 patients presenting for elective repair of abdominal aortic aneurysm. Patients with a positive cardiac history were more likely to have a LVEF of less than or equal to 45 per cent (P less than 0.001). The operative mortality rate was 4 per cent. Each of three patients who died had a LVEF less than or equal to 35 per cent and developed cardiac failure which led to renal failure. Five other patients developed cardiac failure manifested by acute pulmonary oedema during the early postoperative period. There was no statistically significant association between a positive cardiac history and the occurrence of postoperative cardiac failure or death. However, patients with a LVEF of less than or equal to 45 per cent were more likely to develop postoperative cardiac failure (P = 0.004) while patients with a LVEF of less than or equal to 35 per cent had a greater chance of dying (P less than 0.001). No patient died with a LVEF greater than 35 per cent. Preoperative evaluation of LVEF can select patients at high risk of cardiac death from repair of abdominal aortic aneurysm. Such patients could be followed conservatively if they remain asymptomatic and the aneurysm does not enlarge. If operation is considered mandatory, patients with a low LVEF should receive intensive perioperative monitoring with enhancement of ventricular performance.

Dipyridamole-thallium scan for screening of coronary artery disease prior to vascular surgery

Patients with extracranial cerebrovascular disease and peripheral vascular disease are at increased risk of ischaemic heart disease with resulting increased risk of early and late mortality following vascular reconstruction. Over a two year period, 67 patients undergoing carotid or aortic surgery were investigated preoperatively with dipyridamole-thallium scan. There were three positive scans in the first 17 patients; two of these patients suffered a postoperative myocardial infarction (one fatal), compared to none of 14 who had a negative scan (p = 0.02). There were seven positive scans in the next 50 patients. Patients with left main trunk or triple vessel disease were recommended to have coronary artery bypass prior to or combined with the vascular reconstruction. There were no deaths or postoperative myocardial infarction in this group, this improvement in morbidity being statistically significant (p = 0.01). Dipyridamole-thallium scanning is an effective screening procedure for coronary artery disease. Patients with a positive scan are at increased risk of postoperative myocardial infarction following vascular reconstruction. Further investigation with coronary arteriography prior to vascular reconstruction is recommended in patients with positive scans. Coronary artery bypass should be performed prior to or combined with the vascular reconstruction in patients with left main trunk or triple vessel disease.

Ultrasound monitoring of diaphragm activity in bilateral diaphragmatic paralysis

Recovery of diaphragm activity after bilateral diaphragmatic paralysis was monitored in a term infant using a mechanical sector scanner fitted with a 5 MHz transducer. The ratio of diaphragmatic excursion during spontaneous breathing and ventilator assistance was used an objective measure for comparison of diaphragmatic activity during recovery. Ultrasound assessment of diaphragm contraction may be used to study progress in diaphragmatic paralysis.