Precision-guidance vs Systematic Sampling: Optimizing Biopsy Assessment of Secondary Prostate Cancer Suspicious Multiparametric Magnetic Resonance Imaging Lesions.

PURPOSE: We assessed the diagnostic yield of consecutive transperineal targeted biopsy of multiparametric magnetic resonance imaging index lesion and secondary lesion and additive systematic biopsy in patients who received combined targeted biopsy+systematic biopsy of prostate. MATERIALS AND METHODS: Of 1,467 patients with targeted biopsy+systematic biopsy, analyses were restricted to 571 patients with index lesion+secondary lesion, Prostate Imaging-Reporting and Data System score ≥3. Index lesion was defined as having the greatest Prostate Imaging-Reporting and Data System score and/or lesion volume as opposed to secondary lesion. We retrospectively compared clinically significant prostate cancer rates (ie, Gleason Grade Group ≥2) between index lesion+secondary lesion and index lesion+secondary lesion+systematic biopsy. Subgroup analyses in men with ipsilateral index lesion+secondary lesion focused on contralateral systematic biopsy. Multivariable logistic regression analyses to predict any clinically significant prostate cancer included age, previous biopsies, prostate specific antigen density, respective index lesion/secondary lesion volumes, side relation, Prostate Imaging-Reporting and Data System strata, and number of targeted biopsy and systematic biopsy cores. RESULTS: Clinically significant prostate cancer rates for index lesion+secondary lesion vs index lesion+secondary lesion+systematic biopsy were 38% vs 42% (P = .2) at expense of significantly higher median number of biopsy cores (9 vs 25, P < .001). In the subgroup with ipsilateral index lesion+secondary lesion (n = 236), contralateral systematic biopsy detected clinically significant prostate cancer in 17%. In the narrower subgroup with ipsilateral index lesion+secondary lesion (n = 131) without any clinically significant prostate cancer, contralateral systematic biopsy detected clinically significant prostate cancer in 3.8%. Multivariable logistic regression analyses confirmed contralateral systematic biopsy as independent predictor, but performed similarly without systematic biopsy information (area under the curve 87.1% vs 86.6%). CONCLUSIONS: Targeted biopsy of secondary lesion should be included in targeted biopsy protocols due to added diagnostic information. However, for targeted biopsy of index lesion+secondary lesion additional systematic biopsy is of limited informative value in terms of overall clinically significant prostate cancer detection. However, when index lesion+secondary lesion are ipsilateral, contralateral systematic biopsy should be recommended for purpose of prostate lobe information. Our results indicate great potential to reduce systematic biopsy cores and associated potential morbidity, and warrant prospective evaluation.

Suitability of conventional systematic vs. MRI-guided targeted biopsy approaches to assess surgical treatment delay for radical prostatectomy.

OBJECTIVES: To assess if systematic (SBx) vs. transrectal or transperineal mpMRI-ultrasound targeted combined with systematic (TBx + SBx) biopsy confer different effects on treatment delay to radical prostatectomy measured as Gleason grade group (GGG) upgrade of prostate cancer (PCa). MATERIALS AND METHODS: We relied on a multi-institutional cohort of localized PCa patients who underwent RP in Martini-Klinik, Hamburg, or Prostate Center Northwest, Gronau, between 2014 and 2022. Analyses were restricted to PCa GGG 1-3 diagnosed at SBx (n = 4475) or TBx + SBx (n = 1282). Multivariable logistic regression modeling (MVA) predicting RP GGG upgrade of ≥ 1 was performed separately for SBx and TBx + SBx. RESULTS: Treatment delay to RP of < 90, 90-180 and 180-365 days was reported in 59%, 35% and 6.2% of SBx and in 60%, 34% and 5.9% of the TBx + SBx patients, respectively. Upgrade to GGG ≥ 4 at RP was detected in 15% of SBx patients and 0.86% of TBx patients. In MVA performed for SBx, treatment delay yielded independent predictor status (OR 1.17 95% CI 1.02-1.39, p = 0.028), whereas for TBx + SBx MVA, statistical significance was not achieved. CONCLUSION: Treatment delay remained independently associated with radical prostatectomy GGG upgrade after adjustment for clinical variables in the patients diagnosed with SBx alone, but not in those who received combined TBx + SBx. These findings can be explained through inherent misclassification rates of SBx, potentially obfuscating historical observations of natural PCa progression and potential dangers of treatment delay. Thus, mpMRI-guided combined TBx + SBx appears mandatory for prospective delay-based examinations of PCa.

Immune suppression via glucocorticoid-stimulated monocytes: a novel mechanism to cope with inflammation.

Glucocorticoids (GCs) are used as first-line therapies for generalized suppression of inflammation (e.g., allergies or autoimmune diseases), but their long-term use is limited by severe side effects. Our previous work revealed that GCs induced a stable anti-inflammatory phenotype in monocytes, the GC-stimulated monocytes (GCsMs) that we exploited for targeted GC-mediated therapeutic effects. We demonstrate that GCsMs interact with T cells in suppressing proliferation, as well as cytokine release of CD8(+) and, especially, CD4(+) T cells in vitro, and that they support generation of Foxp3(+) cells. Therefore, we tested their immunosuppressive potential in CD4(+) T cell-induced colitis in vivo. We found that injection of GCsMs into mice with severe colitis abolished the inflammation and resulted in significant clinical improvement within a few days. T cells recovered from GCsM-treated mice exhibited reduced secretion of proinflammatory cytokines IFN-γ and IL-17. Furthermore, clusters of Foxp3(+) CD4(+) T cells were detectable at local sites of inflammation in the colon. Thus, GCsMs are able to modify T cell responses in vitro and in vivo, as well as to downregulate and clinically cure severe T cell-mediated colitis.

BCR-ABL enhances differentiation of long-term repopulating hematopoietic stem cells.

In a previously developed inducible transgenic mouse model of chronic myeloid leukemia, we now demonstrate that the disease is transplantable using BCR-ABL(+) Lin(-)Sca-1(+)c-kit(+) (LSK) cells. Interestingly, the phenotype is more severe when unfractionated bone marrow cells are transplanted, yet neither progenitor cells (Lin(-)Sca-1(-)c-kit(+)), nor mature granulocytes (CD11b(+)Gr-1(+)), nor potential stem cell niche cells (CD45(-)Ter119(-)) are able to transmit the disease or alter the phenotype. The phenotype is largely independent of BCR-ABL priming before transplantation. However, prolonged BCR-ABL expression abrogates the potential of LSK cells to induce full-blown disease in secondary recipients and increases the fraction of multipotent progenitor cells at the expense of long-term hematopoietic stem cells (LT-HSCs) in the bone marrow. BCR-ABL alters the expression of genes involved in proliferation, survival, and hematopoietic development, probably contributing to the reduced LT-HSC frequency within BCR-ABL(+) LSK cells. Reversion of BCR-ABL, or treatment with imatinib, eradicates mature cells, whereas leukemic stem cells persist, giving rise to relapsed chronic myeloid leukemia on reinduction of BCR-ABL, or imatinib withdrawal. Our results suggest that BCR-ABL induces differentiation of LT-HSCs and decreases their self-renewal capacity.

Glutamine prevents acute kidney injury by modulating oxidative stress and apoptosis in tubular epithelial cells.

Acute kidney injury (AKI) represents a common complication in critically ill patients that is associated with increased morbidity and mortality. In a murine AKI model induced by ischemia/reperfusion injury (IRI), we show that glutamine significantly decreases kidney damage and improves kidney function. We demonstrate that glutamine causes transcriptomic and proteomic reprogramming in murine renal tubular epithelial cells (TECs), resulting in decreased epithelial apoptosis, decreased neutrophil recruitment, and improved mitochondrial functionality and respiration provoked by an ameliorated oxidative phosphorylation. We identify the proteins glutamine gamma glutamyltransferase 2 (Tgm2) and apoptosis signal-regulating kinase (Ask1) as the major targets of glutamine in apoptotic signaling. Furthermore, the direct modulation of the Tgm2-HSP70 signalosome and reduced Ask1 activation resulted in decreased JNK activation, leading to diminished mitochondrial intrinsic apoptosis in TECs. Glutamine administration attenuated kidney damage in vivo during AKI and TEC viability in vitro under inflammatory or hypoxic conditions.

The functional -374T/A polymorphism of the receptor for advanced glycation end products may modulate Crohn's disease.

The receptor for advanced glycation end products (RAGE) is involved in innate immune mechanisms. Polymorphisms of the RAGE gene have been described as a factor amplifying inflammation in susceptible patients, but the association with Crohn's disease (CD) is not known. The coding RAGE polymorphism G82S (rs2070600) and two promoter polymorphisms, -374T/A (rs1800624) and -429T/C (rs1800625), were studied in two samples from Germany and the United States consisting of 421 and 317 CD patients and 549 and 218 controls, respectively. To test the functional relevance, additional data on serum soluble RAGE (sRAGE), tissue RNA, and protein levels were collected and immunohistochemical stainings of bowel tissue of CD patients and healthy controls as well as models of experimental (dextran sodium sulfate-induced) colitis in RAGE knockout and wild-type mice were performed. The -374T/A RAGE promotor single nucleotide polymorphism (SNP) was negatively associated with CD (odds ratio = 0.708, 95% confidence interval = 0.535-0.938, P = 0.016) and with stenosis (OR = 0.627, P = 0.04) in the German sample. Transmission disequilibrium testing confirmed an undertransmission of the -374A allele. Serum sRAGE levels were higher in patients in complete remission of the -374AA/TA group (1,975 ± 299 pg/ml; -374TT group: 1,310 ± 153 pg/ml SE, P < 0.05) and showed a trend toward decreased levels in CD patients with active disease compared with CD patients in remission. Further in vitro and in vivo studies indicated that an increase of sRAGE ameliorates inflammation. The -429T/C and the G82S polymorphism were not associated with CD. The -374T/A RAGE polymorphism leading to facilitated RAGE gene transcription may to some degree protect from developing a stricturing subphenotype of CD, most likely by increasing levels of sRAGE, which neutralizes proinflammatory mediators.

Outcome of supraselective transarterial chemoembolization in patients with hepatocellular carcinoma.

OBJECTIVE: Hepatocellular carcinoma (HCC) is the most common tumor in cirrhotic patients with a median survival of only 8-10 months if untreated. Supraselective transarterial chemoembolization (STACE) is supposed to be a well-established method for treating HCC patients. In the present study, we evaluated the effect of STACE on post-transplant survival in patients with HCC. MATERIAL AND METHODS: The charts of 53 HCC patients were retrospectively analyzed. Twenty-seven patients had STACE as a bridging therapy while 26 patients were scheduled for liver transplantation (LTX) without prior STACE therapy. A total of 53% of the patients who underwent LTX preoperatively fulfilled the Milan criteria, while 70.6% fulfilled the expanded University of California, San Francisco (UCSF) transplant criteria. Primary endpoint was the post-transplant survival. Statistical analysis included Kaplan-Meier-method, log rank, and chi square tests. RESULTS: Between the LTX groups (STACE vs. non-STACE), there was no significant difference in terms of age, Child classification, Okuda stage, co-morbidities, underlying disease, and post-transplant survival (p > 0.05). Independent of prior STACE, however, disease-free survival after LTX was highly significantly prolonged if LTX was performed within 3 months after initial diagnosis of HCC (p < 0.01) or if patients met the expanded transplant UCSF criteria (p = 0.02). Post-transplant survival did not depend on tumor size. CONCLUSIONS: We conclude that STACE performed prior to LTX does not secure any post-transplant survival benefit, while early LTX, i.e. within 3 months after HCC diagnosis, does improve survival regardless of whether STACE was performed or not. Additionally, fulfillment of the expanded transplant UCSF criteria leads to a prolonged post-transplant survival.

Course of a HBsAg positive liver transplantation in a hepatitis B and D virus coinfected recipient.

The increasing demand for transplantation has led to consideration of liver grafts from donors exposed to hepatitis B virus (HBV). Six transplantations of liver grafts from hepatitis B surface antigen (HBsAg) positive donors have been reported; two recipients suffered from HBV/HDV (hepatitis Delta virus) coinfection and were followed up for 10-12 months. Here, we report a 56 months follow-up of a HBV/HDV-coinfected recipient of a HBsAg positive liver graft. Posttransplant combination prophylaxis consisted of hepatitis immunoglobulin, lamivudine and adefovir dipivoxil. HBsAg remained positive during stable posttransplant follow-up and subclinical HDV reinfection with low replication rate was detected at 1 month. Pegylated interferon therapy was introduced after documentation of histological evidence of mild chronic hepatitis, but without virological response after 48 weeks. Finally, antiviral treatment was switched to tenofovir disoproxil fumarate. More than 50 months posttransplant the recipient revealed clinical symptoms of decompensated liver cirrhosis and has been relisted for liver transplantation. In conclusion HBsAg positive liver grafts in HBsAg positive recipients with HDV coinfection may result in virological recurrence and rapid development of liver cirrhosis.

Prognostic impact of underlying liver fibrosis and cirrhosis after curative resection of hepatocellular carcinoma.

BACKGROUND: In the case of hepatocellular carcinoma (HCC), underlying liver pathology may not only determine the feasibility of surgery but may also affect the postsurgical outcome. We report our experience after curative liver resection for HCC in patients with normal liver, liver fibrosis, and liver cirrhosis. METHODS: A total of 72 patients after liver resection with curative intention were analyzed. Histopathologic findings of tumor-unaffected liver tissue were used for retrospective classification: group A (normal liver); group B (liver fibrosis); group C (liver cirrhosis). The groups were compared for differences in short-term surgical results, total survival, and recurrence-free survival. RESULTS: The rate of major complications was 34.7% and did not significantly differ among groups. The overall perioperative mortality rate was 9.7%, with one patient dying in group A and three patients dying in each of the other two groups. Including perioperative mortality, the median overall survival for the whole group was 37.3 months (95% confidence interval 29.3-45.2 months). The respective 1-, 2-, and 5-year survival rates for group A (n = 21) were 86%, 71%, and 50% and for group C (n = 24) 62%, 50%, and 17%. The overall survival of group B (n = 27) was intermediate (log-rank, P = 0.032). The respective recurrence-free survival rates were 76%, 42%, and 20% for group A and 39%, 13%, and 4% for group C, with group B being intermediate (log-rank, P = 0.016). CONCLUSIONS: Our data demonstrate that liver resection in the presence of compensated liver cirrhosis is feasible but associated with a significantly impaired prognosis for overall and recurrence-free survival. The management of cirrhotic patients with compensated liver function and HCC therefore also requires the opportunity for transplantation.

Genes causing inherited forms of cardiomyopathies. A current compendium.

Cardiomyopathies (diseases of the heart muscle) are a relevant but heterogeneous group of cardiac diseases. The underlying structural myocardial alterations, detectable with contemporary cardiac imaging modalities and also on twelve-lead surface ECG, embody both linkage and differentiation of the respective clinical forms. Most of these are defined to the heart, however, cardiac involvement is also known in the presence of specific metabolic or muscular systemic diseases. In many of the known cardiomyopathies, a genetic background has been elucidated thus indicating a potential familial disease. This, in turn, also harbors the risk that more family members may be affected besides the index patient.

Histone deacetylase inhibition by Entinostat for the prevention of electrical and structural remodeling in heart failure.

BACKGROUND: The development of heart failure is accompanied by complex changes in cardiac electrophysiology and functional properties of cardiomyocytes and fibroblasts. Histone deacetylase (HDAC) inhibitors hold great promise for the pharmaceutical therapy of several malignant diseases. Here, we describe novel effects of the class I HDAC inhibitor Entinostat on electrical and structural remodeling in an in vivo model of pacing induced heart failure. METHODS: Rabbits were implanted a pacemaker system, subjected to rapid ventricular pacing and treated with Entinostat or placebo, respectively. Following stimulation, rabbit hearts were explanted and subsequently subjected to electrophysiological studies and further immunohistological analyses of left ventricles. RESULTS: In vivo, rapid ventricular stimulation caused a significant prolongation of monophasic action potential duration compared to sham hearts (from 173 ± 26 ms to 250 ± 41 ms; cycle length 900 ms; p < 0.05) and an increased incidence of Early afterdepolarisations (+ 150%), while treatment with Entinostat in failing hearts could partially prevent this effect (from 250 ± 41 ms to 170 ± 53 ms, p < 0.05; reduction in EAD by 50%). Entinostat treatment partially restored KCNH2 and Cav1.3 gene expressions in failing hearts, and inhibited the development of cardiac fibrosis in vivo. CONCLUSION: In a rabbit model of heart failure, Entinostat diminishes heart failure related prolongation of repolarization and partially restores KCNH2 and Cav1.3 expression. In addition, Entinostat exerts antifibrotic properties both in vitro and in vivo. Thus, Entinostat might be an interesting candidate for the pharmaceutical therapy of heart failure directed against structural and electrical remodeling.

SERPINB5 Promoter Hypomethylation Differentiates Pancreatic Ductal Adenocarcinoma From Pancreatitis.

OBJECTIVES: The diagnosis of pancreatic ductal adenocarcinoma (PDAC) is challenging in the setting of pancreatitis. We investigated SERPINB5 for its impact on PDAC tumor biology and its use as a diagnostic marker for PDAC in the setting of pancreatitis. METHODS: Patient samples from PDAC primary tumors, PDAC lymph node metastases, and pancreatitis were investigated for SERPINB5 promoter methylation by methylation-specific polymerase chain reaction (PCR). Six PDAC cell lines were investigated in vitro and in vivo using an orthotopic mouse model to generate primary tumors and metastases. SERPINB5 mRNA expression, protein expression, and promoter methylation were determined by quantitative reverse transcriptase-PCR, methylation-specific PCR, and Western Blot. RESULTS: In patient samples, detection of an unmethylated SERPINB5 promoter differentiated pancreatitis from PDAC with a sensitivity of 57% and a specificity of 95% (P < 0.001). SERPINB5 was not deregulated in primary tumors versus metastases, but primary tumors without SERPINB5 protein expression had significantly reduced viability (P = 0.02). CONCLUSIONS: SERPINB5 seems to assume an oncogenic role in PDAC. In clinical samples, detection of unmethylated SERPINB5 was a specific marker for PDAC even in the context of pancreatitis and may provide the basis for a liquid biopsy option to detect PDAC.

The Synthetic Tie2 Agonist Peptide Vasculotide Protects Renal Vascular Barrier Function In Experimental Acute Kidney Injury.

Microvascular barrier dysfunction plays a major role in the pathophysiology of acute kidney injury (AKI). Angiopoietin-1, the natural agonist ligand for the endothelial-specific Tie2 receptor, is a non-redundant endothelial survival and vascular stabilization factor. Here we evaluate the efficacy of a polyethylene glycol-clustered Tie2 agonist peptide, vasculotide (VT), to protect against endothelial-cell activation with subsequent microvascular dysfunction in a murine model of ischemic AKI. Renal ischemia reperfusion injury (IRI) was induced by clamping of the renal arteries for 35 minutes. Mice were treated with VT or PEGylated cysteine before IRI. Sham-operated animals served as time-matched controls. Treatment with VT significantly reduced transcapillary albumin flux and renal tissue edema after IRI. The protective effects of VT were associated with activation of Tie2 and stabilization of its downstream effector, VE-cadherin in renal vasculature. VT abolished the decline in renal tissue blood flow, attenuated the increase of serum creatinine and blood urea nitrogen after IRI, improved recovery of renal function and markedly reduced mortality compared to PEG [HR 0.14 (95% CI 0.05-0.78) P < 0.05]. VT is inexpensive to produce, chemically stable and unrelated to any Tie2 ligands. Thus, VT may represent a novel therapy to prevent AKI in patients.

NG2 proteoglycan as a pericyte target for anticancer therapy by tumor vessel infarction with retargeted tissue factor.

tTF-TAA and tTF-LTL are fusion proteins consisting of the extracellular domain of tissue factor (TF) and the peptides TAASGVRSMH and LTLRWVGLMS, respectively. These peptides represent ligands of NG2, a surface proteoglycan expressed on angiogenic pericytes and some tumor cells. Here we have expressed the model compound tTF-NGR, tTF-TAA, and tTF-LTL with different lengths in the TF domain in E. coli and used these fusion proteins for functional studies in anticancer therapy. We aimed to retarget TF to tumor vessels leading to tumor vessel infarction with two barriers of selectivity, a) the leaky endothelial lining in tumor vessels with the target NG2 being expressed on pericytes on the abluminal side of the endothelial cell barrier and b) the preferential expression of NG2 on angiogenic vessels such as in tumors. Chromatography-purified tTF-TAA showed identical Factor X (FX)-activating procoagulatory activity as the model compound tTF-NGR with Km values of approx. 0.15 nM in Michaelis-Menten kinetics. The procoagulatory activity of tTF-LTL varied with the chosen length of the TF part of the fusion protein. Flow cytometry revealed specific binding of tTF-TAA to NG2-expressing pericytes and tumor cells with low affinity and dissociation KD in the high nM range. In vivo and ex vivo fluorescence imaging of tumor xenograft-carrying animals and of the explanted tumors showed reduction of tumor blood flow upon tTF-TAA application. Therapeutic experiments showed a reproducible antitumor activity of tTF-TAA against NG2-expressing A549-tumor xenografts, however, with a rather small therapeutic window (active/toxic dose in mg/kg body weight).

PD-1 and PD-L1 Expression in NSCLC Indicate a Favorable Prognosis in Defined Subgroups.

BACKGROUND: Immunotherapy can become a crucial therapeutic option to improve prognosis for lung cancer patients. First clinical trials with therapies targeting the programmed cell death receptor PD-1 and its ligand PD-L1 have shown promising results in several solid tumors. However, in lung cancer the diagnostic, prognostic and predictive value of these immunologic factors remains unclear. METHOD: The impact of both factors was evaluated in a study collective of 321 clinically well-annotated patients with non-small lung cancer (NSCLC) using immunohistochemistry. RESULTS: PD-1 expression by tumor infiltrating lymphocytes (TILs) was found in 22%, whereas tumor cell associated PD-L1 expression was observed in 24% of the NSCLC tumors. In Fisher's exact test a positive correlation was found for PD-L1 and Bcl-xl protein expression (p = 0.013). Interestingly, PD-L1 expression on tumor cells was associated with improved overall survival in pulmonary squamous cell carcinomas (SCC, p = 0.042, log rank test), with adjuvant therapy (p = 0.017), with increased tumor size (pT2-4, p = 0.039) and with positive lymph node status (pN1-3, p = 0.010). These observations were confirmed by multivariate cox regression models. CONCLUSION: One major finding of our study is the identification of a prognostic implication of PD-L1 in subsets of NSCLC patients with pulmonary SCC, with increased tumor size, with a positive lymph node status and NSCLC patients who received adjuvant therapies. This study provides first data for immune-context related risk stratification of NSCLC patients. Further studies are necessary both to confirm this observation and to evaluate the predictive value of PD-1 and PD-L1 in NSCLC in the context of PD-1 inhibition.

Adhesion molecules involved in neutrophil recruitment during sepsis-induced acute kidney injury.

Acute kidney injury (AKI) is a common complication in critically ill patients and is associated with high mortality. Recruitment of neutrophils is a hallmark in the pathogenesis of AKI. Although ischemia-reperfusion injury (IRI) is a frequently used research model of AKI, the clinical relevance of IRI-induced AKI is limited. Epidemiologically, sepsis is the prevailing cause of kidney injury. However, it is still unknown whether these distinct entities of AKI share the same pathophysiological mechanisms. This study was initiated to investigate the molecular mechanisms of neutrophil recruitment into the kidney in a murine model of sepsis-induced AKI. By using a flow cytometry-based method, we show that the two ß2-integrins Mac-1 and LFA-1 as well as E-selectin and P-selectin are involved in neutrophil recruitment into the kidney after induction of sepsis. The molecular mechanisms of neutrophil recruitment were further investigated using intravital microscopy, demonstrating that blocking one of these four molecules reduces the number of adherent leukocytes. This was accompanied by a renal upregulation of E-selectin, P-selectin and ICAM-1 (the counter-receptor of ß2-integrins on endothelial cells) after sepsis induction. We conclude that blocking P-selectin, E-selectin, Mac-1 or LFA-1 protects mice from sepsis-induced AKI.

A recurrent activating PLCG1 mutation in cardiac angiosarcomas increases apoptosis resistance and invasiveness of endothelial cells.

Primary cardiac angiosarcomas are rare tumors with unfavorable prognosis. Pathogenic driver mutations are largely unknown. We therefore analyzed a collection of cases for genomic aberrations using SNP arrays and targeted next-generation sequencing (tNGS) of oncogenes and tumor-suppressor genes. Recurrent gains of chromosome 1q and a small region of chromosome 4 encompassing KDR and KIT were identified by SNP array analysis. Repeatedly mutated genes identified by tNGS were KDR with different nonsynonymous mutations, MLL2 with different nonsense mutations, and PLCG1 with a recurrent nonsynonymous mutation (R707Q) in the highly conserved autoinhibitory SH2 domain in three of 10 cases. PLCγ1 is usually activated by Y783 phosphorylation and activates protein kinase C and Ca(2+)-dependent second messengers, with effects on cellular proliferation, migration, and invasiveness. Ectopic expression of the PLCγ1-R707Q mutant in endothelial cells revealed reduced PLCγ1-Y783 phosphorylation with concomitant increased c-RAF/MEK/ERK1/2 phosphorylation, increased IP3 amounts, and increased Ca(2+)-dependent calcineurin activation compared with ectopic expressed PLCγ1-wild-type. Furthermore, cofilin, whose activation is associated with actin skeleton reorganization, showed decreased phosphorylation, and thus activation after expression of PLCγ1-R707Q compared with PLCγ1-wild-type. At the cellular level, expression of PLCγ1-R707Q in endothelial cells had no influence on proliferation rate, but increased apoptosis resistance and migration and invasiveness in in vitro assays. Together, these findings indicate that the PLCγ1-R707Q mutation causes constitutive activation of PLCγ1 and may represent an alternative way of activation of KDR/PLCγ1 signaling besides KDR activation in angiosarcomas, with implications for VEGF/KDR targeted therapies.