Activation of the orphan receptor GPR55 by lysophosphatidylinositol promotes metastasis in triple-negative breast cancer

The orphan G protein-coupled receptor GPR55 has been directly or indirectly related to basic alterations that drive malignant growth: uncontrolled cancer cell proliferation, sustained angiogenesis, and cancer cell adhesion and migration. However, little is known about the involvement of this receptor in metastasis. Here, we show that elevated GPR55 expression in human tumors is associated with the aggressive basal/triple-negative breast cancer population, higher probability to develop metastases, and therefore poor patient prognosis. Activation of GPR55 by its proposed endogenous ligand lysophosphatidylinositol confers pro-invasive features on breast cancer cells both in vitro and in vivo. Specifically, this effect is elicited by coupling to Gq/11 heterotrimeric proteins and the subsequent activation, through ERK, of the transcription factor ETV4/PEA3. Together, these data show that GPR55 promotes breast cancer metastasis, and supports the notion that this orphan receptor may constitute a new therapeutic target and potential biomarker in the highly aggressive triple-negative subtype.

Abstract LB-56: LGR5 is differentially expressed in hepato-gastrointestinal tumors

Background: The orphan G-protein-coupled receptor (GPCR) and Wnt-target protein LGR5 was recently identified as a stem cell marker for cells with intestinal differentiation. In this study we generated a polyclonal anti-LGR5 antibody to investigate protein expression in various hepato-gastrointestinal carcinomas and its correlation with clinico-pathological patient characteristics.

Materials and Methods: Differential expression of LGR5 was studied on transcriptional (real time-polymerase chain reaction) and translational level (immunohistochemistry) in carcinomas and corresponding normal mucosal specimens comprising seven different primary tumor sites, i.e. oesophagus, pancreas, stomach, liver, colon and rectum. The putative clinico-pathological relevance of LGR5-expression in terms of patient survival was studied in tissue micro arrays obtained from a cohort of 488 gastric carcinomas.

Results: We succeeded to establish and characterize a highly specific antibody that recognizes the C-terminal tail of LGR5. LGR5 was differentially expressed on transcriptional and translational level in adenocarcinomas of the oesophagus, pancreas, stomach, colon, rectum, hepatocellular and cholangiocellular carcinoma of the liver compared with the adjacent non-neoplastic tissue. However, in gastric cancer tissue microarrays the expression of LGR5 had no impact on patient survival. Nevertheless, expression of LGR5 by endothelial cells of tumor vessels correlated significantly with the tumor type and tumor grade.

Conclusion: Our results substantiate the significance of LGR5 on the biology of hepato-gastrointestinal carcinomas and provide evidence for its function as potential stem cell marker and candidate therapeutic target in the stomach. With our anti-LGR5 antibody we now have a useful tool for detection and further analyzes of LGR5 biological function.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-56. doi:10.1158/1538-7445.AM2011-LB-56

Loss of XIAP sensitizes colon cancer cells to PPARgamma independent antitumor effects of troglitazone and 15-PGJ2

We investigated whether the anticancer effect of a combination of XIAP down-regulation and PPAR gamma activation on colon cancer is PPARgamma receptor dependent. HCT116-XIAP(+/+) cells and HCT116-XIAP(-/-) cells were treated with troglitazone or 15-deoxy-Delta(12,14)-prostaglandin J2 (15-PGJ2) with or without prior exposure to PPARgamma inhibitor GW9662. Cell proliferation and apoptosis was evaluated. Athymic mice carrying HCT116-XIAP(-/-) cells-derived tumors were treated with troglitazone in the presence or absence of GW9662. Inhibition of cell proliferation and induction of apoptosis by troglitazone and 15-PGJ2 were more prominent in HCT116-XIAP(-/-) cells. PPARgamma ligand-induced growth inhibition, apoptosis, caspase and PARP cleavage could not be blocked by GW9662. Troglitazone significantly retarded growth of xenograft tumors and this effect was not blocked by GW9662. Marked apoptosis and an up-regulation of E-cadherin were observed in xenograft tumor tissues, and GW9662 did not affect these effects. Thus, a combination of XIAP down-regulation and PPARgamma ligands exert a significant anticancer effect in colon cancer via a PPARgamma independent pathway.

Senile seminal vesicle amyloid is derived from semenogelin I

Senile seminal vesicle amyloid (SSVA), one of the most common forms of localized amyloidosis, is associated with the male aging process. Although it had been posited that the amyloidogenic component originated from exocrine cells and that, on the basis of immunohistochemistry, that the amyloid was composed of lactoferrin, the nature of SSVA was never established definitively. To address this issue, we have used our microanalytic techniques to characterize the structure of the congophilic green birefringent protein extracted from 5 such amyloid-containing specimens. Mass spectrometric analysis revealed that in all cases, the fibrils were composed mainly of polypeptide fragments identical in sequence to the N-terminal portion of the major secretory product of seminal vesicles, namely semenogelin I (SgI). Although lactoferrin was detected in 3 instances, the trace amount and seemingly intact form of this molecule indicated that it was not the amyloidogenic molecule. The SgI nature of the amyloid was confirmed through demonstration that the deposits were immunostained specifically with Sgl-reactive antibodies. The results of our research provide unequivocal evidence that SSVA is derived from SgI, and we provisionally designate this form of amyloidosis as ASgI.

Enzymatic and histological alterations in the isolated perfused rat pancreas under conditions of oxidative stress

BACKGROUND

Oxidative stress is a relevant event in the pathogenesis of acute pancreatitis. Investigations in vivo are limited because of the complexity of the organism and the short half-life of free radicals. The isolated perfused rat pancreas could be useful for investigations in the early phase of acute pancreatitis especially under conditions of oxidative stress.

METHODS

External perfusions of the pancreatic glands of Wistar rats were carried out using a modified Krebs-Ringer buffer including an additive of the detergents Triton X-100 and a perfusion including hydrogen peroxide (0.0012%) or tert-butylhydroperoxide (0.0042%) or xanthine oxidase (0.1 U/ml). Changes in amylase, lipase, LDH in the portal outflow fluid and for histological alterations were analyzed.

RESULTS

Damage to pancreatic parenchyma using Triton X-100 was indicated by increased levels of pancreatic enzymes in the perfusion medium. During perfusion with hydrogen peroxide or tert-butylhydroperoxide we found no changes in pancreatic enzymes in the portal outflow. In contrast, perfusion with xanthine oxidase induced a significant elevation in lipase and amylase in the effusion fluid after 30 min. We found a significant increase in edema in the hydrogen peroxide and in the xanthine oxidase group. Focal necroses of the pancreatic parenchyma were detected in all groups of oxidative stress.

CONCLUSIONS

The isolated perfused rat pancreas is a valuable experimental model for investigating the early phase of pathophysiology in acute pancreatitis, for instance, the effect of oxidative stress as an early event in acute pancreatitis. Using hydrogen peroxide tert-butylhydroperoxide or xanthine oxidase, only xanthine oxidase was able to induce a typical elevation in the pancreas enzymes in the effusion fluid.

Investigation of the Presence of Apotipoprotein E, G lycosaminoglycans, Basement Membrane Proteins, and Protease inhibitors in Senile interstitial Amyloid of the Pituitary

The aim of our study was to test whether local- or organ-limited interstitial amyloid of the pituitary is associated with the presence of glycosaminoglycans, basement membrane proteins, protease inhibitors, and apolipoprotein E (apo E), as previously observed in other amyloid syndromes. Serial sections from amyloidotic and nonamyloidotic autopsy pituitaries of patients age 85 yr and over were stained with Congo red, Alcian blue, and, applying immunohistochemistry, with antibodies directed against fibronectin, collagen IV, laminin, apo E, a(1)-antitrypsin and a(1)-antichymotrypsin. Interstitial amyloid was deposited in the immediate vicinity of capillaries and around the acini of the anterior lobe. Glycosaminoglycans were found in capillaries and around the acini of both nonamyloidotic and amyloidotic glands and they were also related spatially to amyloid deposits. Immunostaining of nonamyloidotic and amyloidotic glands demonstrated the presence of fibronectin, collagen IV, and laminin, which was related to basement membranes (fibronectin, collagen IV, and laminin), interstitium, and serum (fibronectin only). In amyloidotic glands, each basement membrane protein presented with an additional spatial relationship to amyloid deposits. Apo E was found in amyloidotic cases only within the amyloid deposits. The results are consistent with the presence of glycosaminoglycans, basement membrane proteins, and apo E in local interstitial amyloid deposits of the pituitary, as previously described in other amyloid syndromes, such as inflammatory related AA-amyloidosis or AB-amyloidosis related to Alzheimer's disease.

Portal amyloid: novel amyloid deposits in gastrointestinal veins?

OBJECTIVE

To specify uncharacterized amyloid deposits in gastrointestinal vessels of the elderly.

MATERIALS AND METHODS

The gastrointestinal tracts from 110 consecutive autopsies of individuals aged 85 years and older were examined for amyloid using Congo red staining. Immunohistochemical classification of the amyloid deposits was conducted using antisera directed against amyloid A, apolipoprotein A-I, apolipoprotein A-II, apolipoprotein B, apolipoprotein C-I, lysozyme, lambda and kappa light chain amyloid fibril proteins, transthyretin, beta2-microglobulin, and amyloid P component. Electron microscopic examination assessed the ultrastructural features.

RESULTS

Thirty-eight (35%) of the 110 cases had gastrointestinal amyloid deposits. In 17 cases the amyloid fibril proteins were defined immunohistochemically. In five cases (5%) the amyloid could not be classified because amyloid deposits were not present in the deeper serial sections used for immunohistochemistry. In 13 cases (11%) the vascular amyloid deposits could not be characterized because they did not demonstrate immunoreactivity with any of a panel of antibodies specific for the fibril proteins of all major extracerebral amyloids. In three individual cases, the vascular amyloid deposits showed variable immunoreactivity, with deposits being negative in some vessels. The immunohistochemically nonreactive vascular amyloid in these 16 cases had several consistent features: it affected only vessels of the small and large intestine, it was limited to mesenteric veins, it consisted of small dot- or comma-like deposits located in close proximity to fragmented elastic fibers, and it demonstrated inconsistent immunostaining for amyloid P component.

CONCLUSIONS

The similar morphologic characteristics of nonreactive gastrointestinal amyloid deposits, which we have designated "portal amyloid," suggest a common origin. Determination of whether portal amyloid represents a new type of amyloid will require chemical analysis.

Amyloid Deposits in Pituitaries and Pituitary Adenomas: Immunohistochemistry and In Situ Hybridization

The patterns of deposition and immunoreactivity of interstitial amyloid were studied in 11 pituitary glands obtained at autopsy and 9 surgically resected pituitary adenomas using Congo red staining and a panel of antisera directed against 5 major amyloid fibril proteins and all pituitary hormones. The deposition pattern of amyloid in pituitary glands differed from that in adenomas but all amyloid deposits showed an immunostaining with anti-amyloid X-light chain. The remaining antisera were immunonegative. In situ hybridization using an oligodeoxyribonucleotide-probe complementary to the mRNA coding for the constant region of human X-light chain yielded no hybridization signals in the pituitaries or pituitary adenomas, excluding local synthesis and secretion of immunoglobulins. Since no case studied suffered from generalized AX-amyloidosis and adsorption of immunoglobulins to the unknown amyloid fribril protein of the pituitary seems to be unlikely, crossreaction of the polyclonal antisera with an undefined antigen is probable. The similar immunostaining properties of amyloid deposits in "normal" pituitaries and pituitary adenomas suggest they both originate from the same precursor protein.