The multiple functions of PrPC in physiological, cancer, and neurodegenerative contexts

Creutzfeldt-Jakob Disease and Fatal Familial Insomnia: Demographics and In-Hospital Mortality in Spain

Background: Creutzfeldt-Jakob disease (CJD) and fatal familial insomnia (FFI) are prion diseases characterized by severe neurodegenerative conditions and a short duration of illness. Methods: This study explores the characteristics of hospitalizations for CJD and FFI in Spain from 2016 to 2022 using the Spanish National Hospital Discharge Database (SNHDD). Results: We identified a total of 1063 hospital discharges, including 1020 for CJD and 43 for FFI. Notably, the number of hospitalized patients with FFI showed a significant peak in 2017. The average length of hospital stay (LOHS) was 13 days for CJD and 6 days for FFI, with in-hospital mortality rates (IHM) of 36.37% for CJD and 32.56% for FFI. Among CJD patients, the average LOHS was 14 days, with a significantly longer duration for those who experienced IHM. Conclusions: The presence of sepsis or pneumonia and older age were associated with a higher IHM rate among CJD patients. The total estimated cost for managing CJD and FFI patients over the study period was EUR 6,346,868. This study offers new insights into the epidemiology and healthcare resource utilization of CJD and FFI patients, which may inform future research directions and public health strategies.

The Humanization and Maturation of an Anti-PrPc Antibody

The cellular prion protein (PrPc) is a cell surface glycoprotein that is highly expressed in a variety of cancer tissues in addition to the nervous system, and its elevated expression is correlated to poor prognosis in many cancer patients. Our team previously found that patients with colorectal cancer (CRC) with high-level PrPc expression had significantly poorer survival than those with no or low-level PrPc expression. Mouse antibodies for PrPc inhibited tumor initiation and liver metastasis of PrPc-positive human CRC cells in mouse model experiments. PrPc is a candidate target for CRC therapy. In this study, we newly cloned a mouse anti-PrPc antibody (Clone 6) and humanized it, then affinity-matured this antibody using a CHO cell display with a peptide antigen and full-length PrPc, respectively. We obtained two humanized antibody clones with affinities toward a full-length PrPc of about 10- and 100-fold of that of the original antibody. The two humanized antibodies bound to the PrPc displayed significantly better on the cell surface than Clone 6. Used for Western blotting and immunohistochemistry, the humanized antibody with the highest affinity is superior to the two most frequently used commercial antibodies (8H4 and 3F4). The two new antibodies have the potential to be developed as useful reagents for PrPc detection and even therapeutic antibodies targeting PrPc-positive cancers.

DNA Aptamer Binding Octapeptide Repeat Region of Cellular Prion Protein

Cellular prion protein (PrPC) is highly expressed in a variety of tumor cells and plays a crucial role in neurodegenerative diseases. Its N-terminal domain contains a conserved octapeptide (PHGGGWGQ) repeat sequence. The number of repeats has been correlated with the species as well as the development of associated diseases. Herein, PrPC was identified to be the molecular target of a high-affinity DNA aptamer HA5-68 obtained by cell-SELEX. Aptamer HA5-68 was further optimized to two short sequences (HA5-40-1 and HA5-40-2), and its binding site to PrPC was identified to be located in the loop-stem-loop region of the head of its secondary structure. HA5 series aptamers were demonstrated to bind the octapeptide repeat region of PrPC, as well as the synthesized peptides containing different numbers of octapeptide repeats. The PrPC expression on 42 cell lines was measured by using aptamer HA5-68 as a molecular probe. The clear understanding of the molecular structure and binding mechanism of this set of aptamers will provide information for the design of diagnostic methods and therapeutic drugs targeting PrPC.

The Multifaceted Functions of Prion Protein (PrPC) in Cancer

The cellular prion protein (PrPC) is a glycoprotein anchored to the cell surface by glycosylphosphatidylinositol (GPI). PrPC is expressed both in the brain and in peripheral tissues. Investigations on PrPC's functions revealed its direct involvement in neurodegenerative and prion diseases, as well as in various physiological processes such as anti-oxidative functions, copper homeostasis, trans-membrane signaling, and cell adhesion. Recent findings have revealed the ectopic expression of PrPC in various cancers including gastric, melanoma, breast, colorectal, pancreatic, as well as rare cancers, where PrPC promotes cellular migration and invasion, tumor growth, and metastasis. Through its downstream signaling, PrPC has also been reported to be involved in resistance to chemotherapy and tumor cell apoptosis. This review summarizes the variance of expression of PrPC in different types of cancers and discusses its roles in their development and progression, as well as its use as a potential target to treat such cancers.

Emerging roles of the cellular prion protein (PrPC) and 37/67 kDa laminin receptor (RPSA) interaction in cancer biology

The cellular prion protein (PrPC) is well-known for its involvement, under its pathogenic protease-resistant form (PrPSc), in a group of neurodegenerative diseases, known as prion diseases. PrPC is expressed in nervous system, as well as in other peripheral organs, and has been found overexpressed in several types of solid tumors. Notwithstanding, studies in recent years have disclosed an emerging role for PrPC in various cancer associated processes. PrPC has high binding affinity for 37/67 kDa laminin receptor (RPSA), a molecule that acts as a key player in tumorigenesis, affecting cell growth, adhesion, migration, invasion and cell death processes. Recently, we have characterized at cellular level, small molecules able to antagonize the direct PrPC binding to RPSA and their intracellular trafficking. These findings are very crucial considering that the main function of RPSA is to modulate key events in the metastasis cascade. Elucidation of the role played by PrPC/RPSA interaction in regulating tumor development, progression and response to treatment, represents a very promising challenge to gain pathogenetic information and discover novel specific biomarkers and/or therapeutic targets to be exploited in clinical settings. This review attempts to convey a detailed description of the complexity surrounding these multifaceted proteins from the perspective of cancer hallmarks, but with a specific focus on the role of their interaction in the control of proliferation, migration and invasion, genome instability and mutation, as well as resistance to cell death controlled by autophagic pathway.