Igor Tsaur

Expression of Foxp3 in Colorectal Cancer but Not in Treg Cells Correlates with Disease Progression in Patients with Colorectal Cancer

Background Regulatory T cells (Treg) expressing the transcription factor forkhead-box protein P3 (Foxp3) have been identified to counteract anti-tumor immune responses during tumor progression. Besides, Foxp3 presentation by cancer cells itself may also allow them to evade from effector T-cell responses, resulting in a survival benefit of the tumor. For colorectal cancer (CRC) the clinical relevance of Foxp3 has not been evaluated in detail. Therefore the aim of this study was to study its impact in colorectal cancer (CRC). Methods and Findings Gene and protein analysis of tumor tissues from patients with CRC was performed to quantify the expression of Foxp3 in tumor infiltrating Treg and colon cancer cells. The results were correlated with clinicopathological parameters and patients overall survival. Serial morphological analysis demonstrated Foxp3 to be expressed in cancer cells. High Foxp3 expression of the cancer cells was associated with poor prognosis compared to patients with low Foxp3 expression. In contrast, low and high Foxp3 level in tumor infiltrating Treg cells demonstrated no significant differences in overall patient survival. Conclusions Our findings strongly suggest that Foxp3 expression mediated by cancer cells rather than by Treg cells contribute to disease progression.

De novo renal cell carcinoma of native and graft kidneys in renal transplant recipients

Study Type – Therapy (case series)

Acetylation of histone H3 prevents resistance development caused by chronic mTOR inhibition in renal cell carcinoma cells

Chronic mTOR inhibition may induce resistance development in renal cell carcinoma (RCC). We analyzed whether long-term exposure of RCC cells to the mTOR-inhibitor RAD001 evokes resistance and whether additional targeting histone deacetylases (HDAC) by valproic acid (VPA) overcomes RAD001 resistance. It is demonstrated that responsiveness to either drug alone is lost over time, evidenced by increased cell growth, proliferation and de-differentiation. However, drug sensitivity was conserved when RAD001 and VPA were applied in concert. Molecular analysis particularly revealed strong re-activation of Akt under chronic RAD001 or diminished histone H3 acetylation under chronic VPA single drug exposure. Combined drug application did not inactivate Akt but rather resulted in H3 acetylation remaining high while RCC cell growth was still reduced. siRNA experiments revealed that histone H3 acetylation is responsible for preserving drug sensitivity in RCCs.

HDAC-inhibition counteracts everolimus resistance in renal cell carcinoma in vitro by diminishing cdk2 and cyclin A

BackgroundTargeted therapies have improved therapeutic options of treating renal cell carcinoma (RCC). However, drug response is temporary due to resistance development.MethodsFunctional and molecular changes in RCC Caki-1 cells, after acquired resistance to the mammalian target of rapamycin (mTOR)-inhibitor everolimus (Cakires), were investigated with and without additional application of the histone deacetylase (HDAC)-inhibitor valproic acid (VPA). Cell growth was evaluated by MTT assay, cell cycle progression and apoptosis by flow cytometry. Target molecules of everolimus and VPA, apoptotic and cell cycle regulating proteins were investigated by western blotting. siRNA blockade was performed to evaluate the functional relevance of the proteins.ResultsEverolimus resistance was accompanied by significant increases in the percentage of G2/M-phase cells and in the IC50. Akt and p70S6K, targets of everolimus, were activated in Cakires compared to drug sensitive cells. The most prominent change in Cakires cells was an increase in the cell cycle activating proteins cdk2 and cyclin A. Knock-down of cdk2 and cyclin A caused significant growth inhibition in the Cakires cells. The HDAC-inhibitor, VPA, counteracted everolimus resistance in Cakires, evidenced by a significant decrease in tumor growth and cdk2/cyclin A.ConclusionIt is concluded that non-response to everolimus is characterized by increased cdk2/cyclin A, driving RCC cells into the G2/M-phase. VPA hinders everolimus non-response by diminishing cdk2/cyclin A. Therefore, treatment with HDAC-inhibitors might be an option for patients with advanced renal cell carcinoma and acquired everolimus resistance.

Resistance after Chronic Application of the HDAC-Inhibitor Valproic Acid Is Associated with Elevated Akt Activation in Renal Cell Carcinoma In Vivo

Targeted drugs have significantly improved the therapeutic options for advanced renal cell carcinoma (RCC). However, resistance often develops, negating the benefit of these agents. In the present study, the molecular mechanisms of acquired resistance towards the histone deacetylase (HDAC) inhibitor valproic acid (VPA) in a RCC in vivo model were investigated. NMRI:nu/nu mice were transplanted with Caki-1 RCC cells and then treated with VPA (200 mg/kg/day). Controls remained untreated. Based on tumor growth dynamics, the mice were divided into “responders” and “non-responders” to VPA. Histone H3 and H4 acetylation and expression of cell signaling and cell cycle regulating proteins in the RCC mouse tumors were evaluated by Western blotting. Tumor growth of VPA responders was significantly diminished, whereas that of VPA non-responders even exceeded control values. Cdk1, 2 and 4 proteins were strongly enhanced in the non-responders. Importantly, Akt expression and activity were massively up-regulated in the tumors of the VPA non-responders. Chronic application (12 weeks) of VPA to Caki-1 cells in vitro evoked a distinct elevation of Akt activity and cancer cells no longer responded with cell growth reduction, compared to the short 2 week treatment. We assume that chronic use of an HDAC-inhibitor is associated with (re)-activation of Akt, which may be involved in resistance development. Consequently, combined blockade of both HDAC and Akt may delay or prevent drug resistance in RCC.

Inhibitory effects of the HDAC inhibitor valproic acid on prostate cancer growth are enhanced by simultaneous application of the mTOR inhibitor RAD001

AIMS To analyze the combined impact of the histone deacetylase (HDAC) inhibitor valproic acid (VPA) and the mammalian target of rapamycin (mTOR) inhibitor RAD001 on prostate cancer cell growth. MAIN METHODS PC-3, DU-145 and LNCaP cells were treated with RAD001, VPA or with an RAD001-VPA combination for 3 or 5 days. Tumor cell growth, cell cycle progression and cell cycle regulating proteins were then investigated by MTT assay, flow cytometry and Western blotting, respectively. Effects of drug treatment on cell signaling pathways were determined. KEY FINDINGS Separate application of RAD001 or VPA distinctly reduced tumor cell growth and impaired cell cycle progression. Significant additive effects were evoked when both drugs were used in concert. Particularly, the cell cycle regulating proteins cdk1, cdk2, cdk4 and cyclin B were reduced, whereas p21 and p27 were enhanced by the RAD001-VPA combination. Signaling analysis revealed deactivation of EGFr, ERK1/2 and p70S6k. Phosphorylation of Akt was diminished in DU-145 but elevated in PC-3 and LNCaP cells. SIGNIFICANCE The RAD001-VPA combination exerted profound antitumor properties on a panel of prostate cancer cell lines. Therefore, simultaneous blockage of HDAC and mTOR related pathways should be considered when designing novel therapeutic strategies for treating prostate carcinoma.

The cdk1-cyclin B complex is involved in everolimus triggered resistance in the PC3 prostate cancer cell line

The growth potential of PC3 prostate cancer cells, sensible (PC3(par)) or resistant (PC3(res)) to the mTOR inhibitor everolimus (RAD001) was investigated. Cell growth and proliferation of PC3(res) was similar to that of PC3(par), and late apoptosis increased in PC3(par) but decreased in PC3(res) following treatment with low dosed everolimus. PC3(res) accumulated in the G2/M-phase, accompanied by cdk1, cdk2 and cyclin B elevation. Knocking down cdk1 or cyclin B distinctly blocked the growth activity of PC3(res). One reason for everolimus resistance may be up-regulation of the cdk1-cyclin B complex in prostate cancer cells, leading to enhanced progression towards G2/M.

Development of urological cancers in renal transplant recipients: 30‐year experience at the Frankfurt Transplant Center

Fatal post‐transplant malignancies with a high proportion of genitourinary neoplasms represent a serious long‐term challenge. With continuous improvement of the allograft and patient survival, cancer development after renal transplantation may soon turn to the leading morbidity cause. In a retrospective single‐center study of 1990 renal transplant recipients between November 1979 and November 2009, records of patients with urological neoplasms including epidemiological, clinical and survival parameters were accessed. Sixty‐six de novo urological malignancies in 58 recipients were recorded in the study period, being most common after skin cancers (15.6% of enregistered tumors). From these, 29 were renal cell cancers, including five neoplasms of transplanted kidney, 24 transitional cell carcinomas, 11 prostate carcinomas, and two germ cell carcinomas with incidence rates of 1.5%, 1.2%, 0.9% and 0.2%, respectively. The patient follow up was virtually complete. Tumor‐related death was found in 44% of cases. By multivariate analysis, no influence of either duration of dialysis, mode or duration of immunosuppression, gender or age at transplantation on overall patient survival could be demonstrated. This study, documenting a 30‐year single center experience, emphasizes the increased risk for urological neoplasms occuring after renal transplantation. Screening strategies for urological cancers should be optimized. (Cancer Sci 2010; 101: 2430–2435)

CCL2 Chemokine as a Potential Biomarker for Prostate Cancer: A Pilot Study

Purpose Prostate specific antigen is not reliable in diagnosing prostate cancer (PCa), making the identification of novel, precise diagnostic biomarkers important. Since chemokines are associated with more aggressive disease and poor prognosis in diverse malignancies, we aimed to investigate the diagnostic relevance of chemokines in PCa. Materials and Methods Preoperative and early postoperative serum samples were obtained from 39 consecutive PCa patients undergoing radical prostatectomy. Serum from 15 healthy volunteers served as controls. Concentrations of CXCL12, CXCL13, CX3CL1, CCL2, CCL5, and CCL20 were measured in serum by Luminex. The expression activity of CXCR3, CXCR4, CXCR5, CXCR7, CXCL12, CXCL13, CX3CR1, CXCL1, CCR2, CCR5, CCR6, CCR7, CCL2, and CCL5 mRNA was assessed in tumor and adjacent normal tissue of prostatectomy specimens by quantitative real-time polymerase chain reaction. The associations of these chemokines with clinical and histological parameters were tested. Results The gene expression activity of CCL2 and CCR6 was significantly higher in tumor tissue compared to adjacent normal tissue. CCL2 was also significantly higher in the blood samples of PCa patients, compared to controls. CCL5, CCL20, and CX3CL1 were lower in patient serum, compared to controls. CCR2 tissue mRNA was negatively correlated with the Gleason score and grading. Conclusion Chemokines are significantly modified during tumorigenesis of PCa, and CCL2 is a promising diagnostic biomarker.

Molecular targeting of prostate cancer cells by a triple drug combination down-regulates integrin driven adhesion processes, delays cell cycle progression and interferes with the cdk-cyclin axis

BackgroundSingle drug use has not achieved satisfactory results in the treatment of prostate cancer, despite application of increasingly widespread targeted therapeutics. In the present study, the combined impact of the mammalian target of rapamycin (mTOR)-inhibitor RAD001, the dual EGFr and VGEFr tyrosine kinase inhibitor AEE788 and the histone deacetylase (HDAC)-inhibitor valproic acid (VPA) on prostate cancer growth and adhesion in vitro was investigated.MethodsPC-3, DU-145 and LNCaP cells were treated with RAD001, AEE788 or VPA or with a RAD-AEE-VPA combination. Tumor cell growth, cell cycle progression and cell cycle regulating proteins were then investigated by MTT-assay, flow cytometry and western blotting, respectively. Furthermore, tumor cell adhesion to vascular endothelium or to immobilized extracellular matrix proteins as well as migratory properties of the cells was evaluated, and integrin α and β subtypes were analyzed. Finally, effects of drug treatment on cell signaling pathways were determined.ResultsAll drugs, separately applied, reduced tumor cell adhesion, migration and growth. A much stronger anti-cancer effect was evoked by the triple drug combination. Particularly, cdk1, 2 and 4 and cyclin B were reduced, whereas p27 was elevated. In addition, simultaneous application of RAD001, AEE788 and VPA altered the membranous, cytoplasmic and gene expression pattern of various integrin α and β subtypes, reduced integrin-linked kinase (ILK) and deactivated focal adhesion kinase (FAK). Signaling analysis revealed that EGFr and the downstream target Akt, as well as p70S6k was distinctly modified in the presence of the drug combination.ConclusionsSimultaneous targeting of several key proteins in prostate cancer cells provides an advantage over targeting a single pathway. Since strong anti-tumor properties became evident with respect to cell growth and adhesion dynamics, the triple drug combination might provide progress in the treatment of advanced prostate cancer.