Whole-Genome/Exome Sequencing Uncovers Mutations and Copy Number Variations in Primary Diffuse Large B-Cell Lymphoma of the Central Nervous System.

Background/objective: Identification of key genetic alterations is of importance in the targeted therapies of primary central nervous system lymphoma (PCNSL). However, only a small number of studies have been carried out in PCNSL. In this study, we further described the genetic mutations and copy number variations (CNVs) in PCNSL patients using whole-genome/exome sequencing (WGS/WES), as well as revealed their associations with patients' clinicopathological features and prognosis. Methods: Tumor specimens from 38 patients with primary diffuse large B-cell lymphoma of the central nervous system (CNS DLBCL) were enrolled to WGS (n = 24) or WES (n = 14). The CNVs and mutations of 24 samples (WGS) and 38 samples (WGS/WES) were characterized, respectively. The associations between CNVs and mutations with the overall survival rates of PCNSL patients were also evaluated. Results: The most common mutations were identified in IGLL5 (68%), PIM1 (63%), MYD88 (55%), CD79B (42%), BTG2 (39%), PCLO (39%), KMT2D (34%), and BTG1 (29%) genes. Among the mutated genes, EP300, ETV6, and HIST1H1E mutations were exclusively detected in the elderly, while DUSP2 mutations were associated with the immune microenvironment indicators. In addition, KMT2D mutation was associated with a poor prognosis. In addition, 488 CNVs including 91 gains and 397 deletions were observed across 24 samples from WGS results. Notably, 1q31.3 amplification was closely associated with the poor prognosis of PCNSL patients. Conclusion: This study further characterizes the genomic landscape of primary CNS DLBCL using WGS/WES, which provides insight into understanding the pathogenesis of PCNSL and fosters new ideas for the targeted treatment of PCNSL.

Molecular profiling of Chinese systemic anaplastic large cell lymphoma patients: novel evidence of genetic heterogeneity.

BACKGROUND: Anaplastic large cell lymphoma (ALCL) is a rare non-Hodgkin lymphoma. A comprehensive understanding of the genetic and clinical heterogeneity of ALCL may help to improve the clinical management of patients with ALCL. However, due to the rarity of the disease, the genetic heterogeneity of ALCL has not been well elucidated. This study aimed to comprehensively elucidate the mutational landscape of tumor tissue samples from patients with systemic ALCL. METHODS: Thirty-six patients with systemic ALCL were enrolled in this retrospective study. Immunohistochemistry (IHC) was performed on tumor tissues at baseline to identify anaplastic lymphoma kinase (ALK) fusions. Capture-based targeted next-generation sequencing (NGS) with a panel spanning 112 lymphoma-related genes, including ALK rearrangements, was also performed on tumor tissue samples. RESULTS: A total of 102 mutations were identified in the entire cohort. Among the 36 patients included in this analysis, 14 (38.8%) were ALK positive, as determined by IHC, while NGS showed 12 patients (33.3%) to harbor ALK rearrangements. Younger patients were more likely to have ALK-positive ALCL (P=0.011). Patients with wild-type (WT) ALK were more likely to have single-nucleotide variants (SNVs) and insertions or deletions (INDELs) than patients with ALK rearrangements (P=0.027). Among the 22 patients with WT ALK, the most commonly mutated genes were TP53 (n=6, 27.3%), followed by NOTCH1 (n=5, 22.7%), KMT2D (n=3, 13.6%), KRAS (n=3, 13.6%), TET2 (n=3, 13.6%), and JAK1 (n=2, 9.1%). Mutations in PRDM1, a commonly mutated gene in ALK-negative patients, were not detected in our ALK-negative cohort. Start-loss of beta-2-microglobulin (B2M) was detected in another patient; this patient had a favorable prognosis, with an overall survival exceeding 19 months. CONCLUSIONS: Our study revealed the unique genomic profiles of Chinese ALCL patients and represents an incremental step in deepening the understanding of the genetic heterogeneity of ALCL patients.

[The expression and significance of nephrin in hepatitis B virus-associated membranous nephropathy].

OBJECTIVE: To observe the expression of nephrin in hepatitis B virus-associated membranous nephropathy (HBV-MN), and investigate the impairment and significance of podocyte in HBV-MN. METHODS: The protein expression of nephrin in renal biopsy specimens in 35 patients, who were diagnosed as HBV-MN by renal biopsy, was determined by immunohistochemistry and tested by semi-quantitative method. The relationship between the expression of nephrin and clinicopathological data was analyzed. RESULTS: Among the 35 cases with HBV-MN, 6 were in MN phase I, 20 in MN phase II and 9 in MN phase III. A strong intensity expression of nephrin in normal glomerulus was found along capillary loop of glomerulus, while its expression in HBV-MN patients decreased obviously. There was no significantly difference in the expression of nephrin among the different stages of HBV-MN (P > 0.05). The expression of nephrin in different clinical types was significantly different(P < 0.05). The expression of nephrin in patients with nephrotic syndrome was significantly lower than that in patients without nephrotic syndrome (P < 0.01). The expression of nephrin in different grades of 24-hour urinary protein excretion quantity was significantly different(P < 0.05). There was negative correlation between the expression of nephrin and 24-hour urinary protein excretion quantity(r = -0.378, P < 0.05). In the patients with HBV-MN phase II, the expression of nephrin in patients with nephrotic syndrome was also significantly lower than that in patients without nephrotic syndrome (P < 0.01). CONCLUSIONS: The damage of podocytes emerge in the early stage of HBV-MN and the expression of nephrin in HBV-MN patients, especially in patients with nephrotic syndrome, are significantly down regulated. The descended expression of nephrin in HBV-MN patients may promote the production of proteinuria.

[Improvement of mouse model for thymic lymphoma induced by N-methyl-N-nitrosourea].

The objective of this study was to elevate the tumorigenic rate of animal model with thymic lymphoma induced by N-methyl-N-nitrosourea (MNU) and to reduce the mortality of this mouse model. The injection regimen and experimental cycle were improved on the basis of previous experiments. The male and female C57BL/6 mice were injected by the intraperitoneal route with MNU solution at different dosages in the first week and the 4th week respectively. Following injection of MNU, the general features of the mice were observed. All mice were sacrificed for autopsy before the 24th experimental week. Complete gross examination was performed for detection of tumor masses. The pathologic and immunohistochemical methods were used to identify the origin and subtype classification of the neoplasm. The results showed that at the 25th week the incidence of thymic lymphoma in mice injected with MNU was 83.3% (55/66), the mortality was 7.6%. In conclusion, improving the program and changing the experimental cycle can increase the tumorigenic rate in the mouse model induced by MNU from 67.5% to 83.3% and reduce the mortality from 10% to 7.6%.

[Pathological features and ultrastructure of N-methyl-N-nitrosourea (MNU)-induced thymic lymphomas in mice].

The objective of study was to investigate the origin and to classify the subtype of N-methyl-N-nitrosourea (MNU)-induced thymic lymphomas in mice. Histopathologic, immunohistochemical and ultrastructural studies were performed to analyze the pathological features of the neoplasms. The results showed that the thymus in all cases became totally replaced by sheets of cells of the lymphoid series. All the tumors coexpressed CD3 and TdT. Transmission electron microscopic study showed the plasma membranes of malignant lymphoma cells were smooth. The nuclear profiles were usually regular, with varying percentage of convoluted nuclei. Few cell organoids were observed in cytoplasm. In conclusion, all the MNU-induced tumor classified by histopathologic, immunohistochemical and ultrastructural studies as precursor lymphoblastic lymphoma that were unquestionably related to the thymus origin and T-cell lineage.

[Establishment of an animal model with thymic lymphoma in mice].

The objective of study was to establish an animal model with thymic lymphoma in mice induced by intraperitoneal injection of DNA alkylating agent N-methyl-N-nitrosourea (MNU). Male and female mice of the C57BL/6 strain were injected by the intraperitoneal route with MNU solution in a dosage of 50 mg/kg body weight. The injection was repeated at week 8. Following injection of MNU, the general status of mice was observed. All mice were sacrificed for autopsy at the 22nd experimental week. Complete gross examination was performed for detection of tumor masses. The results showed that at the 22nd week, the incidence of thymic lymphoma in MNU-treated animals was 67.5% (27/40). No significant sex difference in the incidence of thymic lymphoma was observed. In conclusions, an animal model with thymic lymphoma in mice can be established by twice intraperitoneal administration of MNU. The biological behavior of the induced tumors resembles to those of human thymic lymphoma derived from thymic T-cells.

[Significance of C4d deposition in the follicular lymphoma].

OBJECTIVE: To explore the significance of C4d deposition in follicular lymphoma (FL). METHODS: The deposition of C4d was detected in samples from 133 cases of lymphoma by immunohistochemistry and FL was studied by the double stainings of CD35/C4d, CD21/C4d and Bcl-2/C4d,respectively. RESULTS: Among the 26 FL tissues, irregular C4d deposition was seen in 19 tumor tissues. Double staining for CD35, CD21 or Bcl-2 showed the C4d deposition was around the follicular dendritic cells (FDC). There was no significant difference between the positive rate of C4d and the degree of lymphoma. No deposition was found in the diffuse areas of FL and other type lymphomas. CONCLUSION: C4d deposition around the follicular dendritic cell in the neoplastic follicles is a specific indicator of follicular lymphoma.