Enhanced antitumor activity of a novel, oral, helper epitope-containing WT1 protein vaccine in a model of murine leukemia.

BACKGROUND: A Wilms' tumor 1 (WT1) oral vaccine, Bifidobacterium longum (B. longum) 420, in which the bacterium is used as a vector for WT1 protein, triggers immune responses through cellular immunity consisting of cytotoxic T lymphocytes (CTLs) and other immunocompetent cells (e.g., helper T cells). We developed a novel, oral, helper epitope-containing WT1 protein vaccine (B. longum 2656) to examine whether or not B. longum 420/2656 combination further accelerates the CD4+ T cell help-enhanced antitumor activity in a model of murine leukemia. METHODS: C1498-murine WT1-a genetically-engineered, murine leukemia cell line to express murine WT1-was used as tumor cell. Female C57BL/6 J mice were allocated to the B. longum 420, 2656, and 420/2656 combination groups. The day of subcutaneous inoculation of tumor cells was considered as day 0, and successful engraftment was verified on day 7. The oral administration of the vaccine by gavage was initiated on day 8. Tumor volume, the frequency and phenotypes of WT1-specific CTLs in CD8+ T cells in peripheral blood (PB) and tumor-infiltrating lymphocytes (TILs), as well as the proportion of interferon-gamma (INF-γ)-producing CD3+CD4+ T cells pulsed with WT135-52 peptide in splenocytes and TILs were determined. RESULTS: Tumor volume was significantly smaller (p < 0.01) in the B. longum 420/2656 combination group than in the B. longum 420 group on day 24. WT1-specific CTL frequency in CD8+ T cells in PB was significantly greater in the B. longum 420/2656 combination group than in the B. longum 420 group at weeks 4 (p < 0.05) and 6 (p < 0.01). The proportion of WT1-specific, effector memory CTLs in PB increased significantly in the B. longum 420/2656 combination group than in the B. longum 420 group at weeks 4 and 6 (p < 0.05 each). WT1-specific CTL frequency in intratumoral CD8+ T cells and the proportion of IFN-γ-producing CD3+CD4+ T cells in intratumoral CD4+ T cells increased significantly (p < 0.05 each) in the B. longum 420/2656 combination group than in the 420 group. CONCLUSIONS: B. longum 420/2656 combination further accelerated antitumor activity that relies on WT1-specific CTLs in the tumor compared with B. longum 420.

High prevalence of Wilms tumor 1 expression in multiple myeloma and plasmacytoma: A cohort of 142 Asian patients' samples.

Wilms tumor 1 (WT1) is a promising target antigen for cancer immunotherapy. However, WT1 protein expression and its clinical correlation in multiple myeloma (MM) patients are still limited. We, therefore, investigated WT1 expression in 142 bone marrow and plasmacytoma samples of MM patients at different stages of the disease by immunohistochemistry. The correlations between WT1 expression and clinical parameters or treatment outcomes were evaluated. The overall positive rate of WT1 expression was 91.5%; this high prevalence was found in both bone marrow and plasmacytoma samples, regardless of the disease status. Cytoplasmic WT1 expression was correlated with high serum free light chain ratio at presentation. However, no significant association between WT1 expression and treatment outcome was observed. This study confirms the high prevalence of WT1 expression in an Asian cohort of MM, encouraging the development of immunotherapy targeting WT1 in MM patients, particularly in those with extramedullary plasmacytoma or relapsed disease.

Utility and pitfalls of immunohistochemistry in the differential diagnosis between epithelioid mesothelioma and poorly differentiated lung squamous cell carcinoma.

AIMS: The aims of this study were to clarify the usefulness of immunohistochemistry in the differential diagnosis of epithelioid mesothelioma with a solid growth pattern [solid epithelioid mesothelioma (SEM)] and poorly differentiated squamous cell carcinoma (PDSCC), and to confirm the validity of a specific type of antibody panel. Additionally, we aimed to clarify the pitfalls of immunohistochemical analyses. METHODS AND RESULTS: Formalin-fixed paraffin-embedded specimens from 36 cases of SEM and 38 cases of PDSCC were immunohistochemically examined for calretinin, podoplanin (D2-40), Wilms' tumour gene product (WT1), cytokeratin (CK) 5/6, p40, p63, carcinoembryonic antigen (CEA), epithelial-related antigen (MOC31), claudin-4, thyroid transcription factor-1 (TTF-1), and napsin A. WT1 showed the highest diagnostic accuracy (85.1%) as a mesothelial marker, and CEA, p40 and claudin-4 showed higher diagnostic accuracies (95.9%, 94.6%, and 93.2%, respectively) as carcinoma markers. Calretinin (diagnostic accuracy: 75.7%), D2-40 (diagnostic accuracy: 67.6%), CK5/6 (diagnostic accuracy: 63.5%), TTF-1 (diagnostic accuracy: 55.4%) and napsin A (diagnostic accuracy: 52.7%) could not differentiate between SEM and PDSCC. Among these markers, the combination of calretinin and WT1 showed the highest diagnostic accuracy (86.5%) as a positive marker, and the combination of p40 and CEA showed the highest diagnostic accuracy (97.3%) as a negative marker. The combination of CEA and claudin-4 also showed relatively high diagnostic accuracy (94.6%) as a negative marker. CONCLUSIONS: We recommend the combination of WT1 and calretinin as a positive maker, and the combination of CEA and claudin-4 as a negative marker, for differential diagnoses of SEM and PDSCC.

WT1 protein expression in astrocytic tumors and its relationship with cellular proliferation index.

BACKGROUND: Although Wilms' tumor gene (WT1) was initially known as a tumor marker in Wilms' tumor, nowadays its role is well known in other sorts of malignancy. This study aimed to evaluate WT1 protein expression levels and its association with cellular proliferation in astrocytic brain tumors by immunohistochemical methods. MATERIALS AND METHODS: This cross-sectional study performed on 73 randomly selected archived tissue samples of astrocytic brain tumors. Sections were observed after immunohistochemical staining regarding WT1 protein expression and MIB-1 staining index. Tumors were classified based on World Health Organization grading system. RESULTS: WT1 protein expression was seen in the majority of samples (97.3%) with significantly higher index in high-grade tumors (P<0.001). MIB-1 staining index was also significantly higher in high-grade tumors (P<0.001). Moreover, a significantly positive correlation was found between WT1 protein expression and MIB-1 staining index (r: 0.64, P<0.001). CONCLUSION: Astrocytic brain tumors express WT1 protein. It was also found that high-grade tumors are accompanied with higher WT1 protein expression, which is correlated with MIB-1 staining index. WT1 can be used as a marker of malignant cell proliferation and diagnostic tool to differentiate normal astrocytes from neoplastic cells.

Desmoplastic melanoma associated with an intraepidermal lentiginous lesion: case report and literature review / Melanoma desmoplásico associado a lesão lentiginosa intraepidérmica, com evolução de 10 anos: relato de caso e revisão bibliográfica

Desmoplastic melanoma tends to present as firm, amelanotic papules. Microscopically, it reveals a proliferation of fusiform cells in the dermis and variable collagen deposition, as well as intraepidermal melanocytic proliferation of lentiginous type in most cases. Biopsy in a 61-year-old white male patient, who had received a diagnosis of lentigo maligna on his face 10 years before, revealed a proliferation of dermal pigmented spindle cells and collagen deposition, reaching the deep reticular dermis, with a lentiginous component. Immunohistochemistry with S-100, Melan-A and WT1 showed positivity, but it was weak with HMB45. Desmoplastic melanoma associated with lentigo maligna was diagnosed. Several authors discuss whether desmoplastic melanoma represents a progression from the lentiginous component or arises "de novo". Desmoplastic melanoma represents a minority of cases of primary cutaneous melanoma (less than 4%). Identification of lentigo maligna indicates that desmoplastic melanoma should be carefully investigated.

Os melanomas desmoplásicos apresentam-se como pápulas amelanóticas firmes; à microscopia exibem proliferação de células fusiformes na derme e variável deposição de colágeno, além de proliferação melanocítica lentiginosa, intraepidérmica, na maioria dos casos. Realizada biópsia de pele de paciente masculino, 61 anos, branco, com diagnóstico de lentigo maligno na face, há 10 anos. O exame histopatológico revela proliferação dérmica de células fusiformes pigmentadas e deposição de colágeno, invadindo até a profundidade da derme reticular, associado a componente lentiginoso; presença de positividade imuno-histoquímica com S-100, Melan-A e WT1, e marcação fraca com HMB45. Diagnóstico de melanoma desmoplásico, associado a lentigo maligno. Existe divergência quanto à origem do melanoma desmoplásico, a partir do componente lentiginoso ou "de novo", na ausência de lentigo associado. O melanoma desmoplásico representa uma minoria dos casos de melanoma cutâneo primário (menos de 4%). A presença de lentigo maligno pode servir de sinal de alerta para possível relação com melanoma desmoplásico.

Dual use of a single Wilms' tumor 1 immunohistochemistry in evaluation of ovarian tumors: a preliminary study of 20 cases.

Our previous studies revealed that a single Wilms' tumor 1 (WT-1) immunohistochemistry can be used to elucidate both the myoepithelial cells and blood vessels of human breast tumors. As the human ovary is rich in blood vessels, and WT-1 has been used as a biomarker for ovarian tumors, our current study attempted to assess if a single WT-1 immunohistochemistry has dual usages in evaluation of ovarian tumor and endothelial cells. Paraffin-embedded tissue sections were prepared from 20 cases of ovarian tumors. A set of four consecutive sections from each case were subjected to immunohistochemistry with a mouse monoclonal antibody against the human WT-1 protein, a well defined ovarian tumor marker, CA-125, and a endothelial cell phenotypic marker, CD34, respectively. From each case, 4-5 randomly selected fields were photographed, and expression of these molecules in the same structures were compared. Distinct WT-1 immunoreactivities were seen in both ovarian tumor and endothelial cells. Over 90% of WT-1 positive tumor and endothelial cells were positive for CA-125 and CD34, respectively. Similarly, over 90% of CA-125 or CD34 positive cells co-express WT-1 in tumor or endothelial cells, respectively. Our findings suggest that a single WT-1 immunohistochemistry can be used to assess both the tumor cells and micro-vascular density in ovarian tumors. Our findings also suggest that as WT-1 is expressed in both tumor and endothelial cells, the development of therapeutic agents to target WT-1 may provide an effective treatment option for ovarian cancer.