Alain Mangé

Prion protein as trans-interacting partner for neurons is involved in neurite outgrowth and neuronal survival.

Many uncertainties remain regarding the physiological function of the prion protein PrP and the consequences of its conversion into the pathological scrapie isoform in prion diseases. Here, we show for the first time that different signal transduction pathways are involved in neurite outgrowth and neuronal survival elicited by PrP in cell culture of primary neurons. These pathways include the nonreceptor Src-related family member p59(Fyn), PI3 kinase/Akt, cAMP-dependent protein kinase A, and MAP kinase. Regulation of Bcl-2 and Bax expression also correlates with the survival effect elicited by PrP. The combined results, along with our observation that PrP carries the recognition molecule-related HNK-1 carbohydrate, argue strongly for a role of the molecule in neural recognition by interacting with yet unknown heterophilic neuronal receptors, as shown by comparison of neurite outgrowth from neurons of PrP-deficient and wild-type mice.

Alpha- and beta- cleavages of the amino-terminus of the cellular prion protein

Abstract It is commonly assumed that the physiological isoform of prion protein, PrPC, is cleaved during its normal processing between residues 111/112, whereas the pathogenic isoform, PrPSc, is cleaved at an alternate site in the octapeptide repeat region around position 90. Here we demonstrated both in cultured cells and in vivo, that PrPC is subject to a complex set of post‐translational processing with the molecule being cleaved upstream of position 111/112, in the octapeptide repeat region or at position 96. PrP has therefore two main cleavage sites that we decided to name α and β. Cleavage of PrPC at these sites leads us to re‐evaluate the function of both N‐ and C‐terminus fragments thus generated.

Amphotericin B Inhibits the Generation of the Scrapie Isoform of the Prion Protein in Infected Cultures

ABSTRACT Transmissible spongiform encephalopathies form a group of fatal neurodegenerative disorders that have the unique property of being infectious, sporadic, or genetic in origin. Although some doubts about the nature of the responsible agent of these diseases remain, it is clear that a protein called PrPSc plays a central role. PrPSc is a conformational variant of PrPC, the normal host protein. Polyene antibiotics such as amphotericin B have been shown to delay the accumulation of PrPSc and to increase the incubation time of the disease after experimental transmission in laboratory animals. Unlike for Congo red and sulfated polyanions, no effect of amphotericin B has been observed in infected cultures. We show here for the first time that amphotericin B can inhibit PrPSc generation in scrapie-infected GT1-7 and N2a cells. Its activity seems to be related to a modification of the properties of detergent-resistant microdomains. These results provide new insights into the mechanism of action of amphotericin B and confirm the usefulness of infected cultures in the therapeutic research of transmissible spongiform encephalopathies.

Proteomics-Based Identification of HSP60 as a Tumor-Associated Antigen in Early Stage Breast Cancer and Ductal Carcinoma in situ

The detection of autoantibodies in cancer patients has been shown to constitute an excellent tool for early diagnosis. Because breast cancer still lacks early diagnostic markers, we investigated novel tumor-associated antigens and related autoantibodies in sera from patients with early stage breast cancer compared to autoimmune disease, other cancers, and healthy volunteers, using a proteomics-based approach. Among the 26 protein antigens specifically recognized by early stage breast cancer sera, we focused on Heat Shock Protein 60 (HSP60). Using ELISA, we investigated the frequency of autoantibodies directed against this protein in the sera of 240 individuals, comprising patients with either ductal carcinoma in situ (DCIS) ( n = 49) or early stage breast cancer ( n = 58), other cancers ( n = 20), autoimmune disease ( n = 20), and healthy subjects ( n = 93). Autoantibodies directed against HSP60 were present in 16/49 (31%) early stage breast cancer and 18/58 (32.6%) DCIS patients, compared to 4/93 (4.3%) healthy subjects. In particular, autoantibodies were present in 11/23 patients (47.8%) with high-grade DCIS, compared to 5/26 (19.2%) with low-grade DCIS. HSP60 mRNA levels were significantly higher in primary breast cancer compared to healthy breast tissues. Using immunohistochemistry, we found that HSP60 expression gradually increases from normal through DCIS to invasive tissues. Our results indicate that HSP60 autoantibodies may be of interest in terms of clinical utility for the early diagnosis of breast cancer and more particularly in DCIS. Moreover, HSP60 overexpression during the first steps of breast carcinogenesis may be functionally correlated to tumor growth and/or progression.

PrP-dependent cell adhesion in N2a neuroblastoma cells

The cellular isoform of prion protein (PrPC) is a ubiquitous glycoprotein expressed by most tissues and with a biological function yet to be determined. Here, we have used a neuroblastoma cell model to investigate the involvement of PrP in cell adhesion. Incubation of single cell suspension induced cell–cell adhesion and formation of cell aggregates. Interestingly, cells overexpressing PrP exhibit increased cation‐independent aggregation. Aggregation was reduced after phosphatidylinositol‐specific phospholipase C release of the protein and by pre‐incubation of cells with an antibody raised against the N‐terminal part of PrPC. Our paradigm allows the study of the function of PrP as an intercellular adhesion molecule and a cell surface ligand or receptor.

Identification of a new panel of serum autoantibodies associated with the presence of in situ carcinoma of the breast in younger women.

Purpose: We examined the feasibility of using a panel of autoantibodies to multiple tumor-associated proteins as a method for early detection of breast cancer and, more particularly, carcinoma in situ (CIS). Experimental Design: PPIA, PRDX2, and FKBP52 were identified as early-stage breast cancer autoantigens by proteomic approaches. The seroreactivity of a panel of antibodies consisting of these three antigens and two previously described autoantigens, HSP60 and MUC1, was tested on 235 samples (60 from primary breast cancer patients, 82 from CIS patients, and 93 from healthy controls) with the use of specific ELISAs. FKBP52, PPIA, and PRDX2 mRNA and protein expression levels were evaluated by reverse transcription-PCR and immunohistochemistry in early-stage breast tumors. Results: Three of five autoantibodies, FKBP52, PPIA, and PRDX2, showed significantly increased reactivity in primary breast cancer and CIS compared with healthy controls. When combined, the five markers significantly discriminated primary breast cancer [receiver operating characteristic area under the curve, 0.73; 95% confidence interval (95% CI), 0.60-0.79] and CIS (receiver operating characteristic area under the curve, 0.80; 95% CI, 0.71-0.85) from healthy individuals. Importantly, the receiver operating characteristic–area under the curve value of the autoantibody panel was able to distinguish CIS, including high grades, from healthy controls in women under the age of 50 years (receiver operating characteristic area under the curve, 0.85; 95% CI, 0.61-0.92). Finally, only FKBP52 mRNA and protein levels were found to be increased in CIS and primary breast cancer compared with healthy breast tissue. Conclusions: This autoantibody assay against a panel of five antigens allows for an accurate discrimination between early-stage breast cancer, especially CIS, and healthy individuals. These results could be of interest in detecting early breast cancer as an aid to mammography, especially in women under the age of 50 years with aggressive cancers.

Scrapie-like prion protein is translocated to the nuclei of infected cells independently of proteasome inhibition and interacts with chromatin

Prion diseases are fatal transmissible neurodegenerative disorders characterized by the accumulation of an abnormally folded isoform of the cellular prion protein (PrPC) denoted PrPSc. Recently, wild-type and pathogenic PrP mutants have been shown to be degraded by the endoplasmic reticulum-associated degradation proteasome pathway after translocation into the cytosol. We show here that a protease resistant form of PrP accumulated in the nuclei of prion-infected cells independently of proteasome activity, and that this nuclear translocation required an intact microtubule network. Moreover, our results show for the first time that nuclear PrP interacts with chromatin in vivo, which may have physiopathological consequences in prion diseases

KRAS Mutation Detection in Paired Frozen and Formalin-Fixed Paraffin-Embedded (FFPE) Colorectal Cancer Tissues

KRAS mutation has been unambiguously identified as a marker of resistance to cetuximab-based treatment in metastatic colorectal cancer (mCRC) patients. However, most studies of KRAS mutation analysis have been performed using homogenously archived CRC specimens, and studies that compare freshly frozen specimens and formalin-fixed paraffin-embedded (FFPE) specimens of CRC are lacking. The aim of the present study was to evaluate the impact of tissue preservation on the determination of KRAS mutational status. A series of 131 mCRC fresh-frozen tissues were first analyzed using both high-resolution melting (HRM) and direct sequencing. KRAS mutations were found in 47/131 (35.8%) using both approaches. Out of the 47 samples that were positive for KRAS mutations, 33 had available matched FFPE specimens. Using HRM, 2/33 (6%) demonstrated suboptimal template amplification, and 2/33 (6%) expressed an erroneous wild-type KRAS profile. Using direct sequencing, 6/33 (18.1%) displayed a wild-type KRAS status, and 3/33 (9.1%) showed discordant mutations. Finally, the detection of KRAS mutations was lower among the FFPE samples compared with the freshly frozen samples, demonstrating that tissue processing clearly impacts the accuracy of KRAS genotyping.

Serum Autoantibody Signature of Ductal Carcinoma In Situ Progression to Invasive Breast Cancer

Purpose: The identification of markers associated with progression to invasive breast cancer (IBC) is a major factor that can guide physicians in the initial therapeutic decision and the management of ductal carcinoma in situ (DCIS). Experimental Design: We examined autoantibody targets in 20 DCIS and 20 IBC patients using protein microarrays and identified humoral responses that can be used to distinguish the two groups. The five most differentially targeted antigens were selected to generate an autoantibody signature for the in situ to invasive breast cancer transition. This signature was next tested on 120 independent samples (61 DCIS and 59 IBC) using specific ELISA assays. The prognosis value of the autoantibody signature was finally evaluated in a cohort of DCIS patients followed for 5 years. Results: A set of five autoantibody targets (RBP-Jκ, HMGN1, PSRC1, CIRBP, and ECHDC1) with the highest differential signal intensity found in the protein microarrays experiment was used to establish an autoantibody signature of the DCIS to IBC transition. Using ELISA, this signature significantly discriminated DCIS from IBC [area under the ROC curve (AUC) = 0.794, 95% confidence interval (CI): 0.674–0.877]. Interestingly, our panel could highly distinguish low-grade DCIS from high-grade DCIS exhibiting an AUC of 0.749 (95% CI: 0.581–0.866). Finally, using a Kaplan–Meier analysis, the autoantibody signature could significantly divide the DCIS patients into a poor prognosis group and a good prognosis group (P = 0.01). Conclusion: These results indicate the potential of autoantibody detection as a new prognostic test with possible clinical implications for the management of DCIS. Clin Cancer Res; 18(7); 1992–2000. ©2012 AACR.

Use of autoantibodies to detect the onset of breast cancer.

The widespread use of screening mammography has resulted in increased detection of early-stage breast disease, particularly for in situ carcinoma and early-stage breast cancer. However, the majority of women with abnormalities noted on screening mammograms are not diagnosed with cancer because of several factors, including radiologist assessment, patient age, breast density, malpractice concerns, and quality control procedures. Although magnetic resonance imaging is a highly sensitive detection tool that has become standard for women at very high risk of developing breast cancer, it lacks sufficient specificity and costeffectiveness for use as a general screening tool. Therefore, there is an important need to improve screening and diagnosis of early-invasive and noninvasive tumors, that is, in situ carcinoma. The great potential for molecular tools to improve breast cancer outcomes based on early diagnosis has driven the search for diagnostic biomarkers. Identification of tumor-specific markers capable of eliciting an immune response in the early stages of tumor development seems to provide an effective approach for early diagnosis. The aim of this review is to describe several autoantibodies identified during breast cancer diagnosis. We will focus on these molecules highlighted in the past two years and discuss the potential future use of autoantibodies as biomarkers of early-stage breast cancer.