Since the initial discovery of the oncogenic activity of WNT1 in mouse mammary glands, our appreciation for the complex roles for WNT signalling pathways in cancer has increased dramatically. WNTs and their downstream effectors regulate various processes that are important for cancer progression, including tumour initiation, tumour growth, cell senescence, cell death, differentiation and metastasis. Although WNT signalling pathways have been difficult to target, improved drug-discovery platforms and new technologies have facilitated the discovery of agents that can alter WNT signalling in preclinical models, thus setting the stage for clinical trials in humans.

WNT signalling pathways as therapeutic targets in cancer

Although genetic susceptibility explains the clustering of multiple sclerosis (MS) cases within families and the sharp decline in risk with increasing genetic distance, it cannot fully explain the geographic variations in MS frequency and the changes in risk that occur with migration. Epidemiological data provide some support for the "hygiene hypothesis," but with the additional proviso for a key role of Epstein-Barr virus (EBV) in determining MS risk. We show that whereas EBV stands out as the only infectious agent that can explain many of the key features of MS epidemiology, by itself the link between EBV and MS cannot explain the decline in risk among migrants from high to low MS prevalence areas. This decline implies that either EBV strains in low-risk areas have less propensity to cause MS, or that other infectious or noninfectious factors modify the host response to EBV or otherwise contribute to determine MS risk. The role of infectious factors is discussed here; in a companion article, we will examine the possible role of noninfectious factors and provide evidence that high levels of vitamin D may have a protective role, particularly during adolescence. The primary purpose of these reviews is to identify clues to the causes of MS and to evaluate the possibility of primary prevention.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/ana.21117

Environmental risk factors for multiple sclerosis. Part I: the role of infection.

Epstein-Barr virus (EBV), a ubiquitous B-lymphotropic herpesvirus, has been associated with multiple sclerosis (MS), an inflammatory disease of the central nervous system (CNS), but direct proof of its involvement in the disease is still missing. To test the idea that MS might result from perturbed EBV infection in the CNS, we investigated expression of EBV markers in postmortem brain tissue from MS cases with different clinical courses. Contrary to previous studies, we found evidence of EBV infection in a substantial proportion of brain-infiltrating B cells and plasma cells in nearly 100% of the MS cases examined (21 of 22), but not in other inflammatory neurological diseases. Ectopic B cell follicles forming in the cerebral meninges of some cases with secondary progressive MS were identified as major sites of EBV persistence. Expression of viral latent proteins was regularly observed in MS brains, whereas viral reactivation appeared restricted to ectopic B cell follicles and acute lesions. Activation of CD8+ T cells with signs of cytotoxicity toward plasma cells was also noted at sites of major accumulations of EBV-infected cells. Whether homing of EBV-infected B cells to the CNS is a primary event in MS development or the consequence of a still unknown disease-related process, we interpret these findings as evidence that EBV persistence and reactivation in the CNS play an important role in MS immunopathology.

https://rupress.org/jem/article-pdf/204/12/2899/1160059/jem_20071030.pdf

Dysregulated Epstein-Barr virus infection in the multiple sclerosis brain

ContextEpidemiological studies suggest an association between infection with
Epstein-Barr virus (EBV) and risk of multiple sclerosis (MS).ObjectiveTo determine whether elevation in serum antibody titers to EBV viral
capsid antigen (VCA), nuclear antigens (EBNA, EBNA-1, and EBNA-2), and diffuse
and restricted early antigen (EA-D and EA-R) as well as to cytomegalovirus
(CMV) precede the occurrence of MS.Design, Setting, and SubjectsProspective, nested case-control study. Of 62 439 women participating
in the Nurses' Health Study (aged 30-55 years in 1976) and Nurses' Health
Study II (aged 25-42 years in 1989) who gave blood samples in 1989-1990 and
1996-1999, respectively, and were followed up through 1999, 144 women with
definite or probable MS and 288 healthy age-matched controls were included
in the analysis.Main Outcome MeasureSerum antibody titers to the specific EBV and CMV antigens, compared
between cases and controls.ResultsWe documented 18 cases of MS with blood collected before disease onset.
Compared with their matched controls, these women had higher serum geometric
mean titers (GMTs) of antibodies to EBV but not CMV. Elevations were significant
for antibodies to EBNA-1 (GMT, 515 vs 203; P = .03),
EBNA-2 (GMT, 91 vs 40; P = .01), and EA-D (15.9 vs
5.9; P = .04). The strongest association was found
for antibodies to EBNA-2; a 4-fold difference in titers was associated with
a relative risk (RR) of MS of 3.9 (95% confidence interval [CI], 1.1-13.7).
The corresponding RRs were 1.6 (95% CI, 0.7-3.7) for VCA, 2.5 (95% CI, 1.0-6.3)
for EBNA, 1.8 (95% CI, 1.0-3.1) for EA-D, and 1.0 (95% CI, 0.6-1.7) for CMV.
Significant but generally weaker elevations in anti-EBV antibodies were also
found in analyses of 126 cases of MS with blood collected after disease onset
and their matched controls.ConclusionsOur results support a role of EBV in the etiology of MS.

https://jamanetwork.com/journals/jama/articlepdf/194503/JOC11194.pdf

Epstein-Barr Virus Antibodies and Risk of Multiple Sclerosis: A Prospective Study

Discordance in the histopathologic diagnosis of melanoma and melanocytic nevi between expert pathologists

Purpose: Wnt ligands play a major role in development and are important in cancer. Expression microarray analysis correlates one member of this family, WNT5A, to a subclass of melanomas with increased motility and invasion. There are no large studies of clinical samples primarily addressing the importance of WNT5A in melanoma progression or outcome. Therefore, this study aimed to assess the protein expression of WNT5A during melanoma progression and its effect on outcome. Experimental Design: Expression of WNT5A was determined in a series of 59 primary melanomas with matched metastases. To provide a benchmark of progression against which to assess WNT5A, expression of p16 ink4a was analyzed, as this has been previously well documented in melanoma. The effect of WNT5A protein expression on outcome was assessed in 102 melanomas. Results: Cytoplasmic WNT5A showed a trend of increasing expression with melanoma progression ( P = 0.013), whereas there was diminishing p16 ink4a expression ( P = 0.006). Nevi showed relatively strong WNT5A expression. Strong cytoplasmic WNT5A was an independent risk factor for reduced metastasis-free and overall survival in multivariate analysis ( P = 0.001 and 0.003, respectively). Conclusion: Cytoplasmic WNT5A increases with melanoma progression and strong expression is associated with poor outcome.

https://clincancerres.aacrjournals.org/content/clincanres/14/18/5825.full.pdf

WNT5A Expression Increases during Melanoma Progression and Correlates with Outcome

Epidemiological and serological evidence has suggested a role for Epstein-Barr virus infection in the aetiology of multiple sclerosis. Epstein-Barr virus-specific RNA was looked for in the brains of 10 patients with multiple sclerosis by in situ hybridisation. A total of 21 plaques was examined. In all of these preservation of RNA was shown by hybridisation of control probes to mitochondrial rRNA but no signal was detected with the Epstein-Barr virus probes. It is unlikely that persistent or latent Epstein-Barr virus infection of the CNS occurs in multiple sclerosis, although present findings do not exclude a role for Epstein-Barr virus in the initiation of this disorder.

https://jnnp.bmj.com/content/jnnp/57/8/975.full.pdf

Absence of Epstein-Barr virus RNA in multiple sclerosis as assessed by in situ hybridisation.

We have assessed the degree of observer variation of both Breslow depth and Clark's level in a series of 50 thin malignant melanomas. Our findings are similar to those of previous international studies in the Breslow depth is the more reproducible measure. Significant intra- and inter-observer variation exists and in some cases it was up to +/- 0.86 mm. Even small differences will potentially affect patient management at our centre and this was analysed using kappa statistics. Good agreement was found between observers and this could be improved by comparing the mean of two or more measurements. This removes larger errors, but smaller observer errors and differences in subjective interpretation of the deepest malignant cell mean that agreement will never be more than 90 per cent. This is high compared with studies of observer variation in other pathological conditions, e.g., dysplasia of the cervix, but where surgical management is potentially disfiguring it is not high enough. We conclude that Breslow depth and Clark's level should not be the sole basis of wide excision protocols.

Observer variation in the measurement of Breslow depth and Clark's level in thin cutaneous malignant melanoma.

HLA-DR expression was examined in 50 consecutive primary cutaneous malignant melanomas with a Breslow depth greater than 2 mm using two well-characterized monoclonal antibodies which detect fixation-resistant epitopes. In 31 of these cases (62%) a subpopulation of tumour cells was reactive, although there was considerable heterogeneity. Positive labelling did not correlate with depth but was associated with a reduced likelihood of developing early metastatic disease and a tendency for better overall survival, particularly in male patients. These findings contrast with earlier studies using cryostat sections and one study on paraffin-embedded tissue in which HLA-DR expression was shown to be a poor prognostic factor, but are consistent with the findings in other malignant tumours studied. The significance of HLA-DR expression as a marker of prognosis may depend on the type of tissue preparation, the sensitivity of the immunocytochemical techniques used and the method of assessment.

Is poor prognosis really related to HLA-DR expression by malignant melanoma cells?

Epidermal dendritic and T-cell counts have been performed in lesional and non-lesional skin from 35 psoriatic patients. The aims were to investigate absolute changes and interrelationships between these cellular elements in psoriasis and to explain apparent discrepancies between these results and reports in the literature. In non-lesional skin, the most frequently expressed dendritic cell marker was CD1a. HLA-DR+ and alpha-mannosidase+ dendritic cells were approximately 50 per cent and S100+ cells were 25 per cent as frequent. T-lymphocytes were rare, CD4+ cells predominating. In lesional psoriatic epidermis, there was a definite increase (approximately two-fold) in the absolute number of CD1a+ dendritic cells. This differs from the conclusions from the majority of previous studies. However, when cell counts were expressed per unit area of vertical section, there was a decrease in CD1a+ cells in lesional skin, which is an explanation for this discrepancy. There was a greater increase in absolute HLA-DR+ cell counts, so that the numbers of cells expressing CD1a and HLA-DR were similar in lesional skin. S100 expression increased proportionately with CD1a+, but there was no absolute increase in alpha-mannosidase+ cells, which might represent a separate sub-population of dendritic cells. The greatest cellular increase was in T-lymphocytes, particularly CD8+. In lesional skin, direct correlations have been demonstrated between epidermal thickness, HLA-DR+ dendritic cells and T-lymphocytes, particularly CD8+ cells. We would suggest that the present method of quantification is of value for the analysis of absolute changes in epidermal infiltrates, particularly psoriasis, and could be applied to other epidermal pathologies.

A. Fletcher

Papers

WNT5A Expression Increases during Melanoma Progression and Correlates with Outcome

Absence of Epstein-Barr virus RNA in multiple sclerosis as assessed by in situ hybridisation.

Observer variation in the measurement of Breslow depth and Clark's level in thin cutaneous malignant melanoma.

Is poor prognosis really related to HLA-DR expression by malignant melanoma cells?

Assessment of epidermal dendritic cell markers and T-lymphocytes in psoriasis