Preclinical assesement of survivin and XIAP as prognostic biomarkers and therapeutic targets in gastroenteropancreatic neuroendocrine neoplasia

Abstract

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN) represent a rare and heterogenous tumor entity. Importantly, the highly proliferative subgroup of neuroendocrine carcinoma (GEP-NEC) is characterized by high resistance to conventional chemotherapy. Consequently, there is an urgent need to identify novel therapeutic targets, especially for GEP-NEC. Thus, we focused on Inhibitor of apoptosis protein (IAP) family members survivin and XIAP that orchestrate inhibition of apoptosis, induce resistance against chemotherapeutics and facilitate tumor metastasis. Copy number gains (CNGs) could be detected by microarray comparative genomic hybridization for survivin and XIAP in 60 % and 26.7 % of all GEP-NENs, respectively. Immunohistochemical staining of tissue specimens from 77 consecutive patients with GEP-NEN demonstrated increased survivin protein expression levels in tissue specimens of highly proliferative GEP-NEC or GEP-NEN located in the stomach and colon. In contrast, XIAP overexpression was associated with advanced tumor stages. Knockdown of survivin and XIAP markedly reduced cell proliferation and tumor growth. In vitro, YM155 induced apoptotic cell death accompanied by a reduction in cell proliferation and inhibited GEP-NEC xenograft growth. Taken together, our data provide evidence for a biological relevance of these IAPs in GEP-NEN and support a potential role of survivin as therapeutic target especially in the subgroup of aggressive GEP-NEC.

Survivin and XIAP expression in distinct tumor compartments of surgically resected gastric cancer: XIAP as a prognostic marker in diffuse and mixed type adenocarcinomas

“…Of note, in previous studies using monoclonal as well as aforementioned polyclonal antibodies, we failed to detect survivin splice variants on protein levels (55). Importantly, the specificity of the antibody that we used in our study was also confirmed in knock down experiments that we recently performed (30).…”

“…Formalin-fixed and paraffin embedded (FFPE) tumor specimens were obtained from the Institute of Pathology, University Hospital Duesseldorf. Tissue microarray (TMA) construction was performed as recently described (30). If available two cylinders of 1.0 mm diameter were taken from the tumor center and invasion front, one from tumor surrounding non-malignant mucosa and one from a lymph node metastasis.…”

“…Isotype control was conducted using mouse IgG1 kappa (MOPC-21; Abcam, Cambridge, UK) and rabbit Immunoglobulin Fraction (Code X0903; Dako, Glostrup, Denmark). Expression levels were estimated according to an immunoreactivity score (IRS) as described previously (30)(31)(32).…”

“…Currently, the most intensively investigated survivin antagonist is the small imidazolium-based compound YM155 (Sepantronium bromide). This small molecule survivin inhibitor demonstrated impressive anticancer activity in several preclinical studies using cancer cell lines originating from various types of cancer, including GC cells (30,(48)(49)(50) and was well tolerated in phase I studies (51,52). Concerning the potential efficacy of anti-XIAP treatment strategies in GC initial promising results have been published.…”

Clinicopathological and functional implications of the inhibitor of apoptosis proteins survivin and XIAP in esophageal cancer

“…Two µm thick sections were cut from each TMA block and mounted on superfrost microscope slides. Immunohistochemical staining was performed as recently described (23,24). Two independent investigators (LD and LMJ) blinded to clinicopathological information evaluated the expression of survivin and XIAP using the immunoreactivity score (IRS) according to Remmele (25).…”