No abstract

Recent studies have described a spasmolytic polypeptide-expressing metaplastic cell lineage (SPEM) in the gastric fundic mucosa associated with both chronic H. pylori infection and gastric adenocarcinoma. We investigated the association of SPEM both with early gastric adenocarcinoma and in biopsies taken from patients prior to diagnosis of cancer. Two cohorts were examined. First, gastric resections from 29 patients with early gastric cancer were examined. Second, biopsies taken from 18 patients prior to the diagnosis of gastric cancer were compared with their respective resection specimens as well as with control biopsies from a cohort of 19 patients diagnosed with gastritis without subsequent development of cancer. The presence of SPEM and intestinal metaplasia (IM) adjacent to and distant from the cancer was compared and spasmolytic polypeptide (SP) immunostaining within dysplastic/cancerous cells was identified. SPEM was present adjacent to cancer in all early cancer cases where the tumor was located in the body or at the body/antrum junction, and was present in the body mucosa distant from the cancer in 76% of cases. Intestinal metaplasia was found adjacent to the tumor in 76% of cases and in body sections in 52% of resections. SP immunostaining was noted within cancer cells in 62% of tumors, and within dysplastic cells in 76% of resections where dysplasia was present. SPEM was present in 82% of the biopsies obtained prior to the diagnosis of cancer, compared with only 37% in the gastritis cohort. IM was present in only 57% of biopsies. In conclusion, SPEM is strongly associated with early gastric cancers and is observed in gastric biopsies prior to the development of cancer. In addition, early gastric cancers demonstrated a high incidence of SP expression. These results suggest that SPEM merits consideration as an important pre-neoplastic gastric lesion.

The BIOMED-2 PCR-based immunoglobulin gene rearrangement assays have quickly become the most commonly used laboratory method for detection of B-cell clonality. Therefore, the reliability of these assays under various conditions has become increasingly important. When studying paired cases of follicular lymphoma (FL) from individual patients, we used these assays to assess clonality in 40 formalin-fixed paraffin-embedded (FFPE) specimens from 19 patients diagnosed with FL. The assays of IGH rearrangement failed to give a clonal result in 26/40 (65%) specimens, while the IGK assays failed in only 3/40 (8%) specimens. The high failure rate of the IGH assays for this set of FFPE lymphomas cannot be explained by systematic problems with DNA extraction or amplification because the same IGH assays resulted in a low failure rate (3/32, 9%) for FFPE small lymphocytic lymphoma/chronic lymphocytic leukemia specimens and for fresh frozen FL specimens (1/6, 17%). Furthermore, in a second validation set of 13 FFPE follicular lymphoma the failure rate was 9/13 (69%). Therefore, the BIOMED-2 IGH assay did not perform well on FFPE follicular lymphoma specimens, and the IGK assay may be superior for assessing clonality when no fresh/frozen tissue is available.

No abstract

Chronic lymphocytic leukemia (CLL) can be divided into prognostic subgroups based on the IGHV gene mutational status, and is further characterized by multiple subsets of cases with quasi-identical or stereotyped B cell receptors that also share clinical and biological features. We recently reported differential DNA methylation profiles in IGHV-mutated and IGHV-unmutated CLL subgroups. For the first time, we here explore the global methylation profiles of stereotyped subsets with different prognosis, by applying high-resolution methylation arrays on CLL samples from three major stereotyped subsets: the poor-prognostic subsets #1 (n = 15) and #2 (n = 9) and the favorable-prognostic subset #4 (n = 15). Overall, the three subsets exhibited significantly different methylation profiles, which only partially overlapped with those observed in our previous study according to IGHV gene mutational status. Specifically, gene ontology analysis of the differentially methylated genes revealed a clear enrichment of genes involved in immune response, such as B cell activation (e.g., CD80, CD86 and IL10), with higher methylation levels in subset #1 than subsets #2 and #4. Accordingly, higher expression of the co-stimulatory molecules CD80 and CD86 was demonstrated in subset #4 vs. subset #1, pointing to a key role for these molecules in the crosstalk of CLL subset #4 cells with the microenvironment. In summary, investigation of three prototypic, stereotyped CLL subsets revealed distinct DNA methylation profiles for each subset, which suggests subset-biased patterns of transcriptional control and highlights a key role for epigenetics during leukemogenesis.