Dual role of p53 amyloid formation in cancer; loss of function and gain of toxicity.

The tumor suppressor p53 plays an important role in genome integrity. It is frequently mutated in all types of human cancers, making p53 a key factor in cancer progression. Two phenotypic consequences of these alterations are dominant; a loss of function and a gain of function of p53, which, in several cases, accumulates in intracellular aggregates. Although the nature of such aggregates is still unclear, recent evidence indicates that p53 can undergo conformational transitions leading to amyloid formation. Amyloid diseases, such as, Alzheimer's disease, are characterized by the accumulation of insoluble aggregates displaying the fibrillar conformation. We decided to investigate the propensity of wild type p53 to aggregate and its consequent assembly into different amyloid species, such as oligomers and fibrils; and to determine if these changes in conformation lead to a loss of function of p53. Furthermore, we analyzed cases of Basal Cell Carcinoma (BCC), for the presence of p53 amyloids. Here, we show that p53 forms amyloid oligomers and fibrils, which coincide with p53 inability of binding to DNA consensus sequences. Both p53 amyloid oligomers and fibrils were detected in BCC cancer samples. Additionally, we demonstrate that p53 oligomers are the most cytotoxic to human cell cultures. Our study reveals p53 amyloid formation and demonstrates its dual role in the pathogenesis of cancer by producing a loss of protein function and a gain of toxic function, extensively described in several amyloidogenic diseases. Our results suggest that under certain circumstances, cancer could be considered a protein-conformation disease.

Role of oligomers in the amyloidogenesis of primary cutaneous amyloidosis.

BACKGROUND: Primary cutaneous amyloidosis (PCA) describes a heterogeneous group of cutaneous diseases characterized by amyloid deposition; this may manifest as macules, papules, or nodules, depending on the subtype involved. To date, relatively little is known about the process of amyloidogenesis in the skin; however, investigators recently have identified small amyloid species, known as oligomers, which give rise to large amyloid fibrillar aggregates. OBJECTIVE: The purpose of the current study was to identify small oligomers in patients with PCA using novel immunohistochemical techniques and to examine our findings in light of previous hypotheses of amyloid formation in these diseases. METHODS: Six cases of PCA were analyzed using Congo red, thioflavin S, and hematoxylin-eosin. We also analyzed these samples with the novel oligomer-specific conformational antibody I-11 to detect the small, misfolded protein oligomers. Semiquantitative analysis was performed on these samples to grade the amount of amyloid aggregates and oligomers detected in the skin samples with light and polarized microscopy. RESULTS: In the cases examined, we detected intracellular oligomers in the basal cell layer of the epidermis and the surrounding cells in the dermis. We also were able to detect large aggregates of amyloid in our samples and to correlate the relationship of oligomers to amyloid aggregates in accordance with previous studies on cutaneous amyloidosis and other amyloid-related diseases. LIMITATIONS: Small sample size is a limitation. CONCLUSIONS: PCA is an amyloid-related disease that likely follows a similar mechanism as other more intensively studied amyloid diseases.

Therapeutic removal of amyloid deposits in cutaneous amyloidosis by localised intra-lesional injections of anti-amyloid antibodies.

In the skin, amyloidosis can be found with or without systemic disease. Primary cutaneous amyloidosis defines those amyloidoses restricted to the skin without involvement of other systems. Here, we used conformation-specific antibodies to characterise both fibrillar and oligomeric amyloid aggregates in the skin from patients with cutaneous amyloidosis. Localised cutaneous amyloidosis with different morphology was reproduced in mice by intra-dermal (i.d.) and subdermal administration of amyloid-enhancing factor. Moreover, we demonstrated that conformational antibodies were effective in clearing amyloid deposits caused by localised intra-lesional injections without the necessity of an immune response. Given the accessibility and amyloid localization in this disease, direct i.d. injections of conformational antibodies could be a convenient and direct method for treatment.

Results of a Phase II Trial of Brentuximab Vedotin for CD30+ Cutaneous T-Cell Lymphoma and Lymphomatoid Papulosis.

PURPOSE: Brentuximab vedotin, a monoclonal antibody (cAC10) conjugated to monomethyl auristatin E, targets CD30(+) receptors. This phase II open-label trial was conducted to evaluate safety and efficacy in CD30(+) cutaneous T-cell lymphomas. PATIENTS AND METHODS: Forty-eight patients with CD30(+) lymphoproliferative disorders or mycosis fungoides (MF) received an infusion of 1.8 mg/kg every 21 days. RESULTS: Forty-eight evaluable patients (22 women and 26 men; median age, 59.5 years) had an overall response rate of 73% (95% CI, 60% to 86%; 35 of 48 patients) and complete response rate of 35% (95% CI, 22% to 49%; 17 of 48 patients). Fifteen (54%; 95% CI, 31% to 59%) of 28 patients with MF responded, independent of CD30 expression. In patients with MF/Sézary syndrome, the overall response rate was 50% (five of 10 patients) in patients with low CD30 expression (< 10%), 58% (seven of 12 patients) in patients with medium expression (10% to 50%), and 50% (three of six patients) in patients with high expression (≥ 50%). Time to response was 12 weeks (range, 3 to 39 weeks), and duration of response was 32 weeks (range, 3 to 93 weeks). All patients with lymphomatoid papulosis (n = 9) and primary cutaneous anaplastic T-cell lymphomas (n = 2) responded; time to response was 3 weeks (range, 3 to 9 weeks), and median duration of response was 26 weeks (range, 6 to 44 weeks). Soluble baseline CD30 levels were lowest in complete responders (P = .036). Grade 1 to 2 peripheral neuropathy was observed in 65% of patients (95% CI, 52% to 79%; 31 of 48 patients), is still ongoing in 55% of patients (95% CI, 41% to 69%; 17 of 31 patients), and resolved in 45% of patients (95% CI, 31% to 59%; 14 of 31 patients), with a median time to resolution of 41.5 weeks. Grade 3 to 4 events were neutropenia (n = 5), nausea (n = 2), chest pain (n = 2), deep vein thrombosis (n = 1), transaminitis (n = 1), and dehydration (n = 1). Dose reductions to 1.2 mg/kg were instituted as a result of grade 2 neuropathy (n = 6), transaminitis (n = 1), and arthralgias and fatigue (n = 2). CONCLUSION: Brentuximab vedotin is both active and well tolerated in cutaneous T-cell lymphoma and lymphomatoid papulosis, with an overall response rate of 73% and complete response rate of 35%.

Association of skin with the pathogenesis and treatment of neurodegenerative amyloidosis.

Amyloidosis are a large group of conformational diseases characterized by abnormal protein folding and assembly which results in the accumulation of insoluble protein aggregates that may accumulate systemically or locally in certain organs or tissue. In local amyloidosis, amyloid deposits are restricted to a particular organ or tissue. Alzheimer's, Parkinson's disease, and amyotrophic lateral sclerosis are some examples of neurodegenerative amyloidosis. Local manifestation of protein aggregation in the skin has also been reported. Brain and skin are highly connected at a physiological and pathological level. Recently several studies demonstrated a strong connection between brain and skin in different amyloid diseases. In the present review, we discuss the relevance of the "brain-skin connection" in different neurodegenerative amyloidosis, not only at the pathological level, but also as a strategy for the treatment of these diseases.

Tau oligomers impair memory and induce synaptic and mitochondrial dysfunction in wild-type mice.

BACKGROUND: The correlation between neurofibrillary tangles of tau and disease progression in the brains of Alzheimer's disease (AD) patients remains an area of contention. Innovative data are emerging from biochemical, cell-based and transgenic mouse studies that suggest that tau oligomers, a pre-filament form of tau, may be the most toxic and pathologically significant tau aggregate. RESULTS: Here we report that oligomers of recombinant full-length human tau protein are neurotoxic in vivo after subcortical stereotaxic injection into mice. Tau oligomers impaired memory consolidation, whereas tau fibrils and monomers did not. Additionally, tau oligomers induced synaptic dysfunction by reducing the levels of synaptic vesicle-associated proteins synaptophysin and septin-11. Tau oligomers produced mitochondrial dysfunction by decreasing the levels of NADH-ubiquinone oxidoreductase (electron transport chain complex I), and activated caspase-9, which is related to the apoptotic mitochondrial pathway. CONCLUSIONS: This study identifies tau oligomers as an acutely toxic tau species in vivo, and suggests that tau oligomers induce neurodegeneration by affecting mitochondrial and synaptic function, both of which are early hallmarks in AD and other tauopathies. These results open new avenues for neuroprotective intervention strategies of tauopathies by targeting tau oligomers.

Inhaled insulin forms toxic pulmonary amyloid aggregates.

It is well known that interfaces, such as polar-nonpolar or liquid-air, play a key role in triggering protein aggregation in vitro, in particular the aggregation of peptides and proteins with the predisposition of misfolding and aggregation. Here we show that the interface present in the lungs predisposes the lungs to form aggregation of inhaled insulin. Insulin inhalers were introduced, and a large number of diabetic patients have used them. Although inhalers were safe and effective, decreases in pulmonary capacity have been reported in response to inhaled insulin. We hypothesize that the lung air-tissue interface provides a template for the aggregation of inhaled insulin. Our studies were designed to investigate the harmful potential that inhaled insulin has in pulmonary tissue in vivo, through an amyloid formation mechanism. Our data demonstrate that inhaled insulin rapidly forms amyloid in the lungs causing a significant reduction in pulmonary air flow. Our studies exemplify the importance that interfaces play in protein aggregation in vivo, illustrating the potential aggregation of inhaled proteins and the formation of amyloid deposits in the lungs. These insulin deposits resemble the amyloid structures implicated in protein misfolding disorders, such as Alzheimer's and Parkinson's diseases, and could as well be deleterious in nature.