Kalle Alanen

Stat3 promotes metastatic progression of prostate cancer.

There are currently no effective therapies for metastatic prostate cancer because the molecular mechanisms that underlie the metastatic spread of primary prostate cancer are unclear. Transcription factor Stat3 is constitutively active in malignant prostate epithelium, and its activation is associated with high histological grade and advanced cancer stage. In this work, we hypothesized that Stat3 stimulates metastatic progression of prostate cancer. We show that Stat3 is active in 77% of lymph node and 67% of bone metastases of clinical human prostate cancers. Importantly, adenoviral gene delivery of wild-type Stat3 (AdWTStat3) to DU145 human prostate cancer cells increased the number of lung metastases by 33-fold in an experimental metastasis assay compared with controls. Using various methods to inhibit Stat3, we demonstrated that Stat3 promotes human prostate cancer cell migration. Stat3 induced the formation of lamellipodia in both DU145 and PC-3 cells, further supporting the concept that Stat3 promotes a migratory phenotype of human prostate cancer cells. Moreover, Stat3 caused the rearrangement of cytoplasmic actin stress fibers and microtubules in both DU145 and PC-3 cells. Finally, inhibition of the Jak2 tyrosine kinase decreased both activation of Stat3 and prostate cancer cell motility. Collectively, these data indicate that transcription factor Stat3 is involved in metastatic behavior of human prostate cancer cells and may provide a therapeutic target to prevent metastatic spread of primary prostate cancer.

FZD4 as a Mediator of ERG Oncogene–Induced WNT Signaling and Epithelial-to-Mesenchymal Transition in Human Prostate Cancer Cells

TMPRSS2-ERG and other gene fusions involving ETS factors and genes with strong promoter elements are common in prostate cancer. Although ERG activation has been linked to invasive properties of prostate cancers, the precise mechanisms and pathways of ERG-mediated oncogenesis remain poorly understood. Here, we show that ERG knockdown in VCaP prostate cancer cells causes an activation of cell adhesion, resulting in strongly induced active beta(1)-integrin and E-cadherin expression as well as changes in WNT signaling. These observations were corroborated by data from ERG-overexpressing nontransformed prostate epithelial cells as well as gene expression data from clinical prostate cancer samples, which both indicated a link between ERG and epithelial-to-mesenchymal transition (EMT). Upregulation of several WNT pathway members was seen in ERG-positive prostate cancers, with frizzled-4 (FZD4) showing the strongest overexpression as verified by both reverse transcription-PCR and immunostaining. Both ERG knockin and knockdown modulated the levels of FZD4 expression. FZD4 silencing could mimic the ERG knockdown phenotype by inducing active beta(1)-integrin and E-cadherin expression, whereas FZD4 overexpression reversed the phenotypic effects seen with ERG knockdown. Taken together, our results provide mechanistic insights to ERG oncogenesis in prostate cancer, involving activation of WNT signaling through FZD4, leading to cancer-promoting phenotypic effects, including EMT and loss of cell adhesion.

A prospective diagnostic accuracy study of 18F-fluorodeoxyglucose positron emission tomography/computed tomography, multidetector row computed tomography, and magnetic resonance imaging in primary diagnosis and staging of pancreatic cancer.

Objective:To prospectively compare the accuracy of combined positron emission tomography/computed tomography using 18F-fluorodeoxyglucose (FDG-PET/CT), multidetector row computed tomography (MDCT), and magnetic resonance imaging (MRI) in the evaluation of patients with suspected pancreatic malignancy. Summary Background Data:FDG-PET/CT imaging is increasingly used for staging of pancreatic cancer. Preliminary data suggest a significant influence of FDG-PET/CT on treatment planning, although its role is still evolving. Methods:Thirty-eight consecutive patients with suspicion of pancreatic malignancy were enrolled. Patients underwent a protocol including FDG-PET/CT, MDCT, and MRI combined with magnetic resonance cholangiopancreatography, all of which were blindly evaluated. The findings were confirmed macroscopically at operation and/or by histopathologic analysis (n = 29) or follow-up (n = 9). Results of TNM classification of different imaging methods were compared with clinical TNM classification. Results:Pancreatic adenocarcinoma was diagnosed in 17 patients, neuroendocrine tumor in 3, mass-forming pancreatitis in 4, cystic lesion in 6, and fibrosis in 2. Six patients had a finding of a normal pancreas. The diagnostic accuracy of FDG-PET/CT for pancreatic malignancy was 89%, compared with 76% and 79% for MDCT and MRI, respectively. In the differential diagnosis of suspected malignant biliary stricture at endoscopic retrograde cholangiopancreaticography (n = 21), FDG-PET/CT had a positive predictive value of 92%. In 17 patients with advanced pancreatic adenocarcinoma, FDG-PET/CT had a sensitivity of 30% for N- and 88% for M-staging. Both MDCT and MRI had sensitivities of 30% for N- and 38% for M-staging. Furthermore, the clinical management of 10 patients (26%) was altered after FDG-PET/CT. Conclusion:FDG-PET/CT was more sensitive than conventional imaging in the diagnosis of both primary pancreatic adenocarcinoma and associated distant metastases. In contrast, the sensitivity of FDG-PET/CT was poor in detecting local lymph node metastasis, which would have been important for an assessment of resectability. We recommend the use of FDG-PET/CT in the evaluation of diagnostically challenging cases, especially in patients with biliary strictures without evidence of malignancy in conventional imaging.

Activation of signal transducer and activator of transcription 5 in human prostate cancer is associated with high histological grade.

We have recently identified signal transducer and activator of transcription 5 (Stat5) as a critical survival factor for prostate cancer cells. We now report that activation of Stat5 is associated with high histological grade of human prostate cancer. Specifically, immunohistochemical analysis demonstrated a strong positive correlation with activation of Stat5 and high Gleason score in 114 human prostate cancers. To investigate the mechanisms underlying constitutive activation of Stat5 in prostate cancer, a dominant-negative mutant of Janus kinase 2 (Jak2) was delivered by adenovirus to CWR22Rv cells. Dominant-negative-Jak2 effectively blocked the activation of Stat5 whereas wild-type Jak2 enhanced activation, indicating that Jak2 is the main kinase that phosphorylates Stat5 in human prostate cancer cells. A ligand-induced mechanism for activation of Stat5 in prostate cancer was suggested by the ability of prolactin (Prl) to stimulate activation of both Jak2 and Stat5 in CWR22Rv human prostate cancer cells and in CWR22Rv xenograft tumors. In addition, Prl restored constitutive activation of Stat5 in five of six human prostate cancer specimens in ex vivo long-term organ cultures. Finally, Prl protein was locally expressed in the epithelium of 54% of 80 human prostate cancer specimens with positive correlation with high Gleason scores and activation of Stat5. In conclusion, our data indicate that increased activation of Stat5 was associated with more biologically aggressive behavior of prostate cancer. The results further suggest that Jak2 is the principal Stat5 tyrosine kinase in human prostate cancer, possibly activated by autocrine/paracrine Prl.

In Vivo Imaging of Prostate Cancer Using [68Ga]-Labeled Bombesin Analog BAY86-7548

Purpose: A novel [68Ga]-labeled DOTA-4-amino-1-carboxymethyl-piperidine-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 peptide (BAY86-7548) having high affinity to bombesin receptor subtype II to detect primary and metastatic prostate carcinoma using positron emission tomography/computed tomography (PET/CT) was synthesized and evaluated for prostate cancer. Experimental Design: In this first human study with BAY86-7548, 14 men scheduled for radical prostatectomy (n = 11) or with biochemical recurrence after surgery or hormonal therapy (n = 3) were enrolled. The patients received an intravenous injection of BAY86-7548 followed by over 60-minute dynamic imaging of prostate gland (n = 10) and/or subsequent whole-body imaging (n = 14). The visual assessment of PET/CT images included evaluation of intraprostatic (12 subsextants) and pelvic nodal uptake of BAY86-7548 in 11 surgical patients and detection of potential metastatic foci in all patients. In patients with biochemical recurrence, results were compared with those of either [11C]-acetate (n = 2) or [18F]-fluoromethylcholine (n = 1) PET/CT. Results: We found a sensitivity, specificity, and accuracy of 88%, 81% and 83%, respectively, for detection of primary PCa and sensitivity of 70% for metastatic lymph nodes using histology as gold standard. BAY86-7548 correctly detected local recurrence in prostate bed and showed nodal relapse in accordance with [11C]-acetate PET/CT in 2 patients with biochemical relapse. In the third hormone refractory patient, BAY86-7548 failed to show multiple bone metastases evident on [18F]-fluoromethylcholine PET/CT. Conclusion: BAY86-7548 PET/CT is a promising molecular imaging technique for detecting intraprostatic prostate cancer. Clin Cancer Res; 19(19); 5434–43. ©2013 AACR.

The same endothelial receptor controls lymphocyte traffic both in vascular and lymphatic vessels

The mechanisms controlling the exit of lymphocytes from tissues via lymphatics are practically unknown. We have now identified a 270–300‐kDa molecule designated common lymphatic endothelial and vascular endothelial receptor‐1 (CLEVER‐1) on human lymphatic endothelium and high endothelial venules. We show that it mediates binding of lymphocytes both to high endothelial venules and to lymphatic vessels. Moreover, blocking of the function of CLEVER‐1 results in significant reduction of lymphocyte traffic in vivo. Notably, CLEVER‐1 is also an inducible vascular adhesion molecule for other classes of leukocytes at sites of inflammation in peripheral tissues. These findings suggest that CLEVER‐1 is involved in regulation of lymphocyte recirculation and migration of leukocytes to sites of inflammation and is a potential new target to control inflammation.

Significance of site-specific prognosis of cancer stem cell marker CD44 in head and neck squamous-cell carcinoma

In several recent studies, CD44 expression has been associated with aggressive behavior in cancers of different types. CD44 expression is also linked to cancer stem cells, which have been shown to play a significant role in tumor progression and poor prognosis in head and neck squamous cell carcinoma (HNSCC), as well as in other cancers. Although CD44 is a potential prognostic marker, it has not been adopted to wider clinical use as a part of treatment planning in HNSCC patients. The aim of this research was to study whether CD44 overexpression is associated with 5year overall survival in HNSCC. We also studied site-specific associations between increased CD44 expression and 5year overall survival. Associations between relative tumor CD44 expressions and smoking, heavy alcohol consumption, histological grade of cancer, TNM staging and HNSCC staging were also studied. In total, 135 paraffin-embedded blocks from HNSCC patients were stained immunohistochemically with a CD44 antibody and were classified by the anatomic location of the tumor. CD44 overexpression had statistically significant association with decreased 5year survival rates when all HNSCC samples were studied (p<0.001). Significant association between intense CD44 expression and poor 5year survival rates was found in the patients with SCC of the oro- and hypopharynx (p<0.001) and the larynx (p=0.042). In patients suffering from HNSCC in the oral cavity, CD44 overexpression did not have a significant effect on overall 5year survival rates. Heavy smoking of over 10 pack years had a significant association with tumor CD44 overexpression (p=0.009). Only pharyngeal (p=0.046) and laryngeal (p=0.047) SCC, but not oral-cavity SCC, had statistically significant associations between heavy smoking and CD44 overexpression when HNSCC was studied in regional groups. Alcohol consumption and tumor grade did not have a significant association with the tumors CD44 expression. Our results suggest that CD44 overexpression could be used as a sign of aggressiveness, in addition to the HNSCC staging, as a prognostic factor in pharyngeal and laryngeal HNSCC and to assist in treatment selection.

Stat5 promotes metastatic behavior of human prostate cancer cells in vitro and in vivo.

There are no effective therapies for disseminated prostate cancer. Constitutive activation of Stat5 in prostate cancer is associated with cancer lesions of high histological grade. We have shown that Stat5 is activated in 61% of distant metastases of clinical prostate cancer. Active Stat5 increased metastases formation of prostate cancer cells in nude mice by 11-fold in an experimental metastases assay. Active Stat5 promoted migration and invasion of prostate cancer cells, and induced rearrangement of the microtubule network. Active Stat5 expression was associated with decreased cell surface E-cadherin levels, while heterotypic adhesion of prostate cancer cells to endothelial cells was stimulated by active Stat5. Activation of Stat5 and Stat5-induced binding of prostate cancer cells to endothelial cells were decreased by inhibition of Src but not of Jak2. Gene expression profiling indicated that 21% of Stat5-regulated genes in prostate cancer cells were related to metastases, while 7.9% were related to proliferation and 3.9% to apoptosis. The work presented here provides the first evidence of Stat5 involvement in the induction of metastatic behavior of human prostate cancer cells in vitro and in vivo. Stat5 may provide a therapeutic target protein for disseminated prostate cancer.

Vascular adhesion protein-1, intercellular adhesion molecule-1 and P-Selectin mediate leukocyte binding to ischemic heart in humans

OBJECTIVES The expression of endothelial adhesion molecules and their functional significance in leukocyte adhesion to human myocardial blood vessels in acute myocardial infarction (AMI) were studied. BACKGROUND Leukocyte extravasation, mediated by specific adhesion molecules, exacerbates tissue injury after restoration of blood supply to an ischemic tissue. Experimental myocardial reperfusion injury can be alleviated with antibodies that block the function of adhesion molecules involved in leukocyte emigration, but the relevant molecules remain poorly characterized in human AMI. METHODS Semiquantitative immunohistochemistry and in vitro adhesion assays were used to study the expression and granulocyte binding abilities of different endothelial adhesion molecules in human AMI. Changes in the molecular nature of vascular adhesion protein-1 (VAP-1) were evaluated using immunoblotting. RESULTS Certain endothelial adhesion molecules (intercellular adhesion molecule [ICAM-2], CD31 and CD73) were expressed in myocardial blood vessels homogeneously in normal and ischemic hearts, whereas others (E-selectin and peripheral lymph node addressin) were completely absent from all specimens. The synthesis of ICAM-1 was locally, and that of P-selectin regionally, upregulated in the infarcted hearts when compared with nonischemic controls. Vascular adhesion protein-1 showed ventricular preponderance in expression and alterations in posttranslational modifications during ischemia-reperfusion. Importantly, P-selectin, ICAM-1 and VAP-1 mediated granulocyte binding to blood vessels in the ischemic human heart. CONCLUSIONS Human P-selectin, ICAM-1 and VAP-1 appear to be the most promising targets when antiadhesive interventions preventing leukocyte-mediated tissue destruction after myocardial ischemia are planned.

Cancer-associated fibroblasts, a parameter of the tumor microenvironment, overcomes carcinoma-associated parameters in the prognosis of patients with mobile tongue cancer

Mobile tongue squamous cell carcinoma (MTSCC) is known for its strong propensity for regional metastasis and poor patient survival despite aggressive treatment, thus calling for new and reliable markers for predicting prognosis and guiding therapeutic management. Towards this end, three classes of markers were investigated: cancer-associated fibroblasts (CAFs; α-SMA positivity) as a representative of the tumor microenvironment, maspin (mammary serine protease inhibitor) as a tumor marker likely to be modulated by factors within the tumor microenvironment, and DNA content and Ki-67 labeling index as inbuilt tumor markers in 128 cases of MTSCC using immunohistochemistry and image cytometry. Of these markers, only CAF density was independently and relatively strongly associated with elevated mortality from MTSCC. The hazard ratio in the CAF-rich type of tumor microenvironment was 4.85 (95% CI 1.41-16.6, versus the CAF-poor) when adjusted by proportional hazards modeling for the center where the patient was managed, gender, tumor stage, presence of neck metastasis and age at diagnosis. CAF density was unrelated to non-MTSSC mortality. Given the strong association between increased CAF density and higher mortality in MTSCC, routine assessment of CAF density for disease course prognosis and inclusion as an integral part of treatment protocols are recommended.