AR-V7 Protein Expression in Circulating Tumour Cells Is Not Predictive of Treatment Response in mCRPC.

INTRODUCTION: Androgen receptor variant 7 (AR-V7) plays an important role in the progression of castration-resistant prostate cancer (CRPC) and has shown potential as a predictive biomarker in circulating tumour cells (CTCs) isolated from the bloodstream in terms of a liquid biopsy. Studies have shown that AR-V7 is a potential surrogate for selecting drug classes for systemic treatment by detecting nuclear AR-V7 by immunofluorescence or measuring AR-V7 messenger RNA by quantitative PCR. Here, we assessed the predictive value of AR-V7 detected by classical immunohistochemistry (IHC) for treatment response. METHODS: CTCs were isolated by cell separation by density gradient centrifugation from patients with metastatic CRPC (n = 26) before, while, and after undergoing a new therapy with chemotherapy (cabazitaxel or docetaxel) or antiandrogen (enzalutamide or abiraterone). CTCs were sequentially cytospun on object slides, and AR-V7 status was then detected by IHC based on a staining regime established on a 22Rv1 cell line with antibodies against CK8/18 und AR-V7. RESULTS: AR-V7 status detected by IHC showed no predictive value for progression-free survival (PFS). Kaplan-Meier analysis revealed that there was no difference in PFS between patients found positive or negative for AR-V7. DISCUSSION/CONCLUSION: AR-V7 detected by classical IHC has no predictive value for treatment response in the described setting. The future role of AR-V7 in CTCs as a biomarker in clinical routine remains elusive.

Latent heparanase facilitates VLA-4-mediated melanoma cell binding and emerges as a relevant target of heparin in the interference with metastatic progression.

Heparanase is an endo-ß-glucuronidase that enzymatically cleaves heparan sulfates (HS) and heparan sulfate proteoglycan (HSPG) structures. Heparanase expression levels by tumors were correlated with cell invasion, angiogenic activity, and poor prognosis. Heparanase can also possess pro-tumorigenic effects independent of its enzymatic activity. Using human melanoma MV3 cells, we demonstrate that latent heparanase activates in a tightly temporary-regulated manner the binding function of the integrin very late antigen-4 (VLA-4), an important component in the metastatic spread of melanoma cells. shRNA-mediated knockdown of syndecan-4 (SDC-4) indicated that this proteoglycan is the key element to convey heparanase binding via focal adhesion complex formation, detected by vinculin staining, to an upregulated VLA-4 binding function. This inside-out signaling pathway of VLA-4 involved activated FAK and Akt, but apparently not PKCα/δ. VLA-4, however, appears representative of other integrins which together impact the heparanase/integrin activation axis in tumorigenicity. Biosensor measurements provided an insight as to how heparin can interfere with this activation process. While low-molecular-weight heparin (LMWH) cannot replace heparanase bound to SDC-4, LMWH can compete with SDC-4 binding of heparanase. Since blockade of heparanase by LMWH has functional consequences for reduced VLA-4 binding, latent heparanase appears as a novel, so far unnoticed target of heparin, underlying its antimetastatic activity.

PIAS1 is not suitable as a urothelial carcinoma biomarker protein and pharmacological target.

Urothelial cancer (UC) is one of the most common cancers in Europe and is also one of the costliest to treat. When first line therapies show initial success, around 50% of cancers relapse and proceed to metastasis. In this study we assessed the Protein inhibitor of activated signal transducers and activators of transcription (PIAS)1 as a potential therapeutic target in urothelial cancer. PIAS1 is a key regulator of STAT1 signalling and may be implicated in carcinogenesis. In contrast to other cancer types PIAS1 protein expression is not significantly different in malignant areas of UC specimens compared to non-malignant tissue. In addition, we found that down-regulation and overexpression of PIAS1 had no effect on the viability or colony forming ability of tested cell lines. Whilst other studies of PIAS1 suggest an important biological role in cancer, this study shows that PIAS1 has no influence on reducing the cytotoxic effects of Cisplatin or cell recovery after DNA damage induced by irradiation. Taken together, these in vitro data demonstrate that PIAS1 is not a promising therapeutic target in UC cancer as previously shown in different entities such as prostate cancer (PCa).

sE-cadherin is upregulated in serum of patients with renal cell carcinoma and promotes tumor cell dissemination in vitro.

INTRODUCTION: Cadherin family proteins are involved in the tumorigenesis of several malignancies. However, their significance in renal cell carcinoma (RCC) has not been extensively investigated. The current study investigates the potential of several cadherins to perform as biomarkers for tumor detection and exert functional RCC activity. METHODS: Pre- and postoperative concentrations of sE-cadherin, cadherin-6, N-cadherin, cadherin-11, cadherin-17, and cadherin-5 were measured in serum of patients undergoing surgery for RCC and correlated to clinical and histopathological parameters. Control serum was obtained from healthy volunteers. A498 and Caki-1 cells were incubated with sE-cadherin and assessed for cell growth, adhesion, and chemotaxis. RESULTS: sE-cadherin was significantly upregulated in RCC patients, as compared to controls, and discriminated them with striking accuracy (area under the curve value 0.83). Serum levels remained stable several days after surgery. Treating A498 and Caki-1 cancer cells with various concentrations of sE-cadherin attenuated cell growth and adhesion, while chemotaxis was augmented. CONCLUSIONS: sE-cadherin is overexpressed in serum of RCC patients and provides a functional cellular switch from sessility to aggressive dissemination. While sE-cadherin is not tumor-specific and thus inappropriate for population-based screening, further studies are warranted to investigate its role in monitoring RCC and employing it as a therapeutic target.

Experimental imaging in orthotopic renal cell carcinoma xenograft models: comparative evaluation of high-resolution 3D ultrasonography, in-vivo micro-CT and 9.4T MRI.

In this study, we aimed to comparatively evaluate high-resolution 3D ultrasonography (hrUS), in-vivo micro-CT (µCT) and 9.4T MRI for the monitoring of tumor growth in an orthotopic renal cell carcinoma (RCC) xenograft model since there is a lack of validated, non-invasive imaging tools for this purpose. 1 × 106 Caki-2 RCC cells were implanted under the renal capsule of 16 immunodeficient mice. Local and systemic tumor growth were monitored by regular hrUS, µCT and MRI examinations. Cells engrafted in all mice and gave rise to exponentially growing, solid tumors. All imaging techniques allowed to detect orthotopic tumors and to precisely calculate their volumes. While tumors appeared homogenously radiolucent in µCT, hrUS and MRI allowed for a better visualization of intratumoral structures and surrounding soft tissue. Examination time was the shortest for hrUS, followed by µCT and MRI. Tumor volumes determined by hrUS, µCT and MRI showed a very good correlation with each other and with caliper measurements at autopsy. 10 animals developed pulmonary metastases being well detectable by µCT and MRI. In conclusion, each technique has specific strengths and weaknesses, so the one(s) best suitable for a specific experiment may be chosen individually.