Update on novel agents in renal cell carcinoma

CD151 promotes cell metastasis via activating TGF-β1/Smad signaling in renal cell carcinoma

Tetraspanin CD151 has been identified as a tumor promoter, which is upregulated in various malignant cell types. However, the function of CD151 and its underlying mechanism in renal cell carcinoma is still unknown. In this study, we detected the expression of CD151 in RCC cells and tissues and explored its regulatory mechanism. We found that CD151 was upregulated in renal cell carcinoma tissues and cells and its expression was significantly associated with tumor stage (p=0.019) and survival (p=0.001) by analyzing tissue microarrays. After silencing of CD151 via lentivirus vector in Caki-1 and Caki-2 cells, reduced ability of migration and invasion were detected with downregulation of CD151. The opposite results were observed in cells with CD151 overexpression. Furthermore, western blotting was performed to investigate the influence of CD151 on epithelial-to-mesenchymal transition, matrix metalloproteinase 9 and TGF-β1/Smad signaling pathway in RCC. Subsequently, upregulating the protein level of transforming growth factor-β1 in cells with silencing of CD151 could rescue the malignant behaviors inhibited, which indicated that CD151 may play its promoting role in RCC partially by stimulating the expression of TGF-β1. Conclusively, CD151 might exhibit a prominent role in migration and invasion of RCC cells via activating TGF-β1/Smad signaling pathway.

Simultaneous targeting of VEGF-receptors 2 and 3 with immunoliposomes enhances therapeutic efficacy

BACKGROUND

Tumor progression depends on angiogenesis. Vascular endothelial growth factor (VEGF) receptors (VEGFRs) are the main signal transducers that stimulate endothelial cell migration and vessel sprouting. At present, only VEGFR2 is targeted in the clinical practice.

PURPOSE

To develop new, anti-angiogenic nanoparticles (immunoliposomes, ILs), that redirect cytotoxic compounds to tumor-associated vascular cells.

METHODS

Pegylated liposomal doxorubicin (PLD) was targeted against VEGFR2- and VEGFR3-expressing cells by inserting anti-VEGFR2 and/or anti-VEGFR3 antibody fragments into the lipid bilayer membrane of PLD. These constructs were tested in vitro, and in vivo in the Rip1Tag2 mouse model of human cancer.

RESULTS

The combination treatment with anti-VEGFR2-ILs-dox and anti-VEGFR3-ILs-dox was superior to targeting only VEGFR2 cells and provides a highly efficient approach of depleting tumor-associated vasculature. This leads to tumor starvation and pronounced reduction of tumor burden.

CONCLUSION

Nanoparticles against VEGFR2 and -3 expressing tumor-associated endothelial cells represent a promising and novel anti-cancer strategy.

Targeted treatments in advanced renal cell carcinoma: focus on axitinib

Antiangiogenesis options have evolved rapidly in the last few years, with an increasing number of agents currently approved by the US Food and Drug Administration and European Medicines Agency. Angiogenesis inhibitors have been shown to be very effective for the treatment of metastatic renal cancer cell. Axitinib is a third-generation inhibitor of vascular endothelial growth factor receptor and is currently being developed for the treatment of various malignancies. The pharmacokinetic properties of axitinib may have a selective therapeutic effect, with minimal adverse reactions and enhanced safety. In a large Phase III study of previously treated patients with metastatic renal cell carcinoma, axitinib achieved a longer progression-free survival than sorafenib with an acceptable safety profile and good quality of life. This review focuses on the pharmacology, pharmacokinetics, and clinical activity of axitinib in the current treatment of renal cell carcinoma. The role of axitinib in the adjuvant and/or neoadjuvant setting needs to be evaluated in further clinical trials.

In vivo delivery of siRNA targeting vasohibin-2 decreases tumor angiogenesis and suppresses tumor growth in ovarian cancer

Vasohibin-2 (VASH2) is a homolog of vasohibin-1 and exhibits pro-angiogenic activity. We recently reported that VASH2 is expressed in certain ovarian cancers and promotes tumor growth through angiogenesis. To further demonstrate the effectiveness of molecular targeting of VASH2 for anticancer treatment, we applied in vivo delivery of siRNA targeting VASH2 (siVASH2) using atelocollagen to a xenograft model of ovarian cancer. We inoculated mice s.c. with DISS and SKOV-3, two representative human ovarian serous adenocarcinoma cell lines. When tumors were measurable, we initiated treatment with control or siVASH2 mixed with atelocollagen, which enveloped the whole tumor. Treatment with siVASH2 significantly inhibited s.c. tumor growth by abrogating tumor angiogenesis. We confirmed that expression of VASH2 mRNA in the tumor was downregulated by siVASH2 treatment. In addition, the siVASH2-treated tumor contained more blood vessels covered with pericytes, indicating that knockdown of VASH2 contributes to the normalization of tumor blood vessels. Based on these results, VASH2 may be a promising molecular target for ovarian cancer treatment.

Histologic variations and immunohistochemical features of metastatic clear cell renal cell carcinoma

BACKGROUND

Due to advancements in treatment of metastatic and advanced renal cell carcinoma (RCC), it has become increasingly important to diagnose metastatic RCC and the specific subtype. In this study, we investigated the diverse histologic features of metastatic clear cell renal cell carcinoma (CCRCC) cases in comparison with corresponding primary lesions.

METHODS

We identified 119 metastatic CCRCC cases from 81 corresponding primary lesions diagnosed between 1995 and 2010 and evaluated the diverse histologic and immunohistochemical features of these lesions.

RESULTS

A total of 44 primary lesions (54.3%) had a non-clear cell component in addition to a typical clear cell component. Of the 119 metastatic lesions, 63 lesions (52.9%) contained a non-clear cell component, and 29 metastatic lesions were composed of a non-clear cell component only. Rhabdoid features were the most frequent non-clear cell histology among the metastatic lesions. Metastatic CCRCCs mainly showed positive CD10 and epithelial membrane antigen staining and negative cytokeratin 7 staining.

CONCLUSIONS

Metastatic CCRCC commonly showed a variety of histologic features. If there is a difficulty to diagnose metastatic CCRCC due to a variety of histologic features or small biopsy specimen, histologic review of the primary lesion and immunohistochemical analysis can help determine the correct diagnosis.

Feline sarcoma-related protein expression correlates with malignant aggressiveness and poor prognosis in renal cell carcinoma

Feline sarcoma-related protein (Fer) is a ubiquitously expressed non-receptor protein tyrosine kinase associated with proliferation in various cancer cells. However, no reports have described the pathological roles and prognostic value of Fer expression in renal cell carcinoma (RCC). We investigated Fer expression in three RCC cell lines (ACHN, Caki-1, and Caki-2) and in normal tubule cells (HK-2) by immunoblotting. Fer expression was highest in ACHN cells, with Caki-1 showing intermediate levels and Caki-2 showing low levels, and was undetectable in HK-2. RNA interference was therefore used to assess the effects of Fer knockdown in ACHN. Knockdown of Fer expression was found to inhibit RCC cell proliferation and colony formation. Immunohistochemical analysis of 131 human RCC tissues (110 conventional, 11 chromophobe, and 10 papillary) investigated relationships between Fer expression and clinicopathological features, including cancer cell proliferation, apoptosis, and prognostic value for survival. In human tissues, Fer expression was significantly higher in cancer cells than in normal tubules. In addition, expression levels correlated with cancer cell proliferation, but not with apoptosis. Multivariate analysis indicated associations of Fer expression with pT stage, tumor grade, and metastasis (P < 0.001). Fer expression was also prognostic for cause-specific survival according to multivariate analysis (hazard ratio, 3.89; 95% confidence interval, 1.02-14.84, P = 0.047). Fer expression correlates with RCC cell proliferation both in vitro and in vivo, and with tumor progression and survival. This represents useful information for discussing the pathological and clinical significance of Fer in RCC.

Downregulation of vasohibin-2, a novel angiogenesis regulator, suppresses tumor growth by inhibiting angiogenesis in endometrial cancer cells

The vasohibin-2 (VASH2) gene was originally found to be expressed in infiltrating mononuclear cells of a mouse model of hypoxia-induced subcutaneous angiogenesis. These cells are mobilized from bone marrow to promote angiogenesis. Recently, VASH2 has been demonstrated to be expressed in several types of cancer in which it promotes tumor development through angiogenesis. However, its role in endometrial cancer remains unknown. Using quantitative reverse transcription-polymerase chain reaction (RT-PCR), we found that VASH2 was overexpressed in several human endometrial cancer cell lines, including the HEC50B cell line, which we used to further examine the role of VASH2. Although knockdown of VASH2 with stable transfection of shRNA had little effect on the proliferation of HEC50B cells in vitro, knockdown in an in vivo murine xenograft model inhibited tumor growth by decreasing tumor angiogenesis. In addition, the supernatant from HEC50B cells that expressed VASH2 significantly promoted the proliferation of human umbilical vein endothelial cells. By contrast, knockdown of VASH2 significantly attenuated the proliferative effect. These results indicate that VASH2 contributes to the development of endometrial cancer by promoting angiogenesis through a paracrine mode of action. Consequently, VASH2 may be considered to be a novel molecular target for endometrial cancer therapy.

Bilateral renal cell carcinoma metastasis in the oral cavity

Cancer metastases to the oral cavity are reported infrequently. Renal cell carcinoma has a high metastatic potential, with approximately one third of patients presenting with metastatic disease. New lesions in the oral cavity often rely on preoperative biopsy to establish the diagnosis. However, we report an unusual case in a setting of known renal cell carcinoma disease, where initial pathology and culture data were misleading. Appropriate follow-up and a high index of suspicion will remain necessary. Surgical excision is the treatment of choice.

Angiogenesis inhibition by the maleimide-based small molecule GNX-686

We investigated the anti-angiogenic properties of GNX-686, a newly identified maleimide-based small molecule. In vitro studies on HUVEC showed that GNX-686 inhibited cell growth with an ED(50) of 20-25 μM, while human HeLa tumor cells and non-transformed embryonic mouse fibroblasts were less sensitive for the drug. More importantly, at 4 μM, a concentration that was non-toxic to any cell in culture, GNX-686 showed a significant inhibitory effect on tube formation by HUVEC, indicating a profound anti-angiogenic activity. Angiogenesis inhibition was subsequenly tested in the chorioallantoic membrane (CAM) of the chicken embryo. A significant angiostatic activity was observed in the CAM model, and results were compared with the effect of bevacizumab, a well known and clinically used VEGF inhibitor. Under our experimental conditions, GNX-686 was found to be as effective as bevacizumab, significantly changing the morphology of the vascular network, as illustrated and quantified by the relative number of branching points and the relative mean mesh size of the vascular network. In another in vivo model of neovascularization, the mouse retinopathy of prematurity (ROP), the vascular network of GNX-686-treated mice was significantly altered, reducing the density of the retinal microvasculature, as compared to the control retinas. Immunohistochemical processing of the GNX-686 treated (4μM) eyes showed over 50% reduction of the number of cell nuclei associated with neovasculature, as compared to the control-treated eye. Taken together these results demonstrate that GNX-686 is a promising anti-angiogenic compound that could be developed for the treatment of diseases characterized by aberrant angiogenesis such as ocular pathologies and cancer.

NCCN Task Force report: optimizing treatment of advanced renal cell carcinoma with molecular targeted therapy

The outcome of patients with metastatic renal cell carcinoma has been substantially improved with administration of the currently available molecularly targeted therapies. However, proper selection of therapy and management of toxicities remain challenging. NCCN convened a multidisciplinary task force panel to address the clinical issues associated with these therapies in attempt to help practicing oncologists optimize patient outcomes. This report summarizes the background data presented at the task force meeting and the ensuing discussion.

CD151 expression can predict cancer progression in clear cell renal cell carcinoma

AIMS

CD151 is known to be implicated in cancer progression and metastasis. The aim was to evaluate the expression of CD151 in clear cell renal cell carcinoma (CCRCC) and to assess its prognostic significance.

METHODS AND RESULTS

The expression of CD151 was evaluated in 489 cases of CCRCC by immunohistochemistry. Immunoreactivity was classified into four categories (minimal, 0-10% positive cells; focal, 10-50% positive cells; diffuse moderate, >50% positive cells with moderate staining intensity; diffuse strong, >50% positive cells with strong staining). To determine the statistical significance of CD151 expression in CCRCC, all cases were divided into two groups based on their CD151 expression level: a CD151-low group (n=257; minimal and focal) and a CD151-high group (n=232; diffuse). Expression of CD151 was correlated positively with pT, pN, pM categories, pathological tumour-node-metastasis (pTNM) stage, nuclear grade, tumour size and patient's age. The CD151-high group had significantly shorter cancer-specific survival (P<0.001) and progression-free survival (P<0.001) times. Furthermore, multivariate analysis showed that CD151 expression was an independent predictor for tumour progression in patients with CCRCC (P=0.040).

CONCLUSIONS

High CD151 expression is associated with advanced stage and high nuclear grade in CCRCC. CD151 is a prognostic marker for tumour progression in CCRCC patients.

Effects of bevacizumab in mouse model of endometrial cancer: Defining the molecular basis for resistance

Endometrial cancer is the most frequent gynecologic cancer in women. Long-term outcomes for patients with advanced stage or recurrent disease are poor. Targeted molecular therapy against the vascular endothelial growth factor (VEGF) and its receptors constitute a new therapeutic option for these patients. The goal of our study was to assess the potential effectiveness of inhibition of VEGF/VEGFR signaling in a xenograft model of endometrial cancer using bevacizumab (Avastin, a humanized antibody against VEGFA). We also aimed to identify molecular markers of sensitivity or resistance to this agent. We show that bevacizumab retards tumor growth in athymic mice by inhibiting molecular components of signaling pathways that sustain cell survival and proliferation. We also demonstrate that resistance to bevacizumab may involve up-regulation of anti-apoptotic genes and certain proto-oncogenes. We propose that down-regulation of ARHGAP6 and MMP15 transcripts indicates that tumors are sensitive to bevacizumab whereas inhibition of PKCδ- or S6K-dependent signaling and up-regulation of TNFRS4 or MMP13 and MMP14 mark a developing resistance to bevacizumab therapy. Interestingly, the significant activation of c-Jun oncogene detected in bevacizumab-treated tumors suggests that, in endometrial cancers, the c-Jun-mediated pathway(s) contribute to bevacizumab resistance.

Quantification of HLA class I molecules on renal cell carcinoma using Edman degradation

BACKGROUND

Unimpaired HLA class I antigen presentation is a prerequisite for the recognition of tumor cells by cytotoxic T lymphocytes and thus essential for the success of anticancer immunotherapeutic concepts. Several approaches have been taken in the immunotherapy of metastatic renal cell carcinoma (RCC), however of limited success. HLA loss or down-regulation have often been reported and might interfere with immunotherapeutic approaches aimed at the recognition of HLA-presented peptides.

METHODS

We employed a quantitative method of molecular analysis for the comparison of HLA amounts on primary tumor, normal kidney and metastases of RCC, using Edman degradation. We analyzed a series of 47 RCC samples including corresponding renal parenchyma, local lymph node metastases and distant metastases.

RESULTS

Results of quantitative Edman degradation revealed significantly higher HLA yields on primary tumor and metastases compared to normal kidney tissue. This effect was shown not to result from infiltrating immune cells, since tumor-infiltrating lymphocytes had no influence on the overall HLA recovery from tumor tissue. Unexpectedly, we found a higher amount of HLA class I molecules on distant metastases compared to local lymph node metastases.

CONCLUSION

Edman degradation allows the direct quantitative comparison of HLA class I protein expression by tumor or normal tissue and metastases of RCC patients. Our results raise hopes for improving the success and effectiveness of future immunotherapeutic concepts for metastatic RCC.

Radiotherapy in combination with vascular-targeted therapies

BACKGROUND

Given the critical role of tumor vasculature in tumor development, considerable efforts have been spent on developing therapeutic strategies targeting the tumor vascular network. A variety of agents have been developed, with two general approaches being pursued. Antiangiogenic agents (AAs) aim to interfere with the process of angiogenesis, preventing new tumor blood vessel formation. Vascular-disrupting agents (VDAs) target existing tumor vessels causing tumor ischemia and necrosis. Despite their great therapeutic potential, it has become clear that their greatest clinical utility may lie in combination with conventional anticancer therapies. Radiotherapy is a widely used treatment modality for cancer with its distinct therapeutic challenges. Thus, combining the two approaches seems reasonable.

CONCLUSIONS

Strong biological rationale exist for combining vascular-targeted therapies with radiation. AAs and VDAs were shown to alter the tumor microenvironment in such a way as to enhance responses to radiation. The results of preclinical and early clinical studies have confirmed the therapeutic potential of this new treatment strategy in the clinical setting. However, concerns about increased normal tissue toxicity, have been raised.