Chromosome abnormalities of gastric cancer detected in cancerous effusions

Novel t(7;10)(p22;p24) along with NPM1 mutation in patient with relapsed acute myeloid leukemia

Chromosomal abnormalities/genetic mutations associated with hematological malignancies alter the structure and function of genes controlling cell proliferation and differentiation through multiple and complex pathways, resulting different clinical outcomes. This is a case study of a lady presented with acute myeloid leukemia (AML M1) at our center who relapsed 10 years after the induction therapy. Cytogenetic and molecular analyses were performed in this case at the time of relapse to find out the chromosomal abnormalities and genetic abnormalities like FMS-like tyrosine kinase (FLT3) and nucleophosmin (NPM1) mutation. The cytogenetic analysis of bone marrow established a novel translocation t(7;10) (p22;q24) in 100% of the cells analyzed. Phytohaemagglutinin (PHA)-stimulated blood culture also revealed the same abnormality. Apart from this, the molecular analysis showed NPM1 exon 12 (hot-spot) mutation in this patient. This was the first report of novel chromosomal translocation in this subset of AML in which a new translocation along with NPM1 mutation was discussed.

Recurrent chromosomal rearrangements at bands 8q24 and 11q13 in gastric cancer as detected by multicolor spectral karyotyping

AIM: To identify chromosomal translocations specific to gastric cancer (GC), spectral karyotyping (SKY) analysis was performed on established cell lines and cancerous ascitic fluids.

METHODS: SKY analysis of 10 established cell lines and seven cancerous ascitic fluid samples identified recurrent chromosomal breakpoints and translocations in GC, several of which involved chromosomal loci of oncogenes or tumor suppressor genes.

RESULTS: A total of 630 chromosomal breaks were identified. Chromosome no.8 was the most frequently involved in rearrangements (65 breaks), followed by chromosomes no.11 (53), no. 1 (49), no. 7 (46), no. 13 (37), no. 3 (36), no. 17 (33), and no. 20 (29). Frequent breakpoints were detected in 8q24.1 (30 breaks), 11q13 (29), 13q14 (16), 20q11.2 (14), 7q32 (13), 17q11.2 (13), 18q21 (12), 17q23 (9), 18q11.2 (9). SKY analysis identified a total of 242 chromosomal rearrangements including 190 reciprocal and non-reciprocal translocations. The recurrent combinations of chromosomal bands involved in translocations were 8q24.1 and 13q14 (3 cases), 8q24.1 and 11q13 (3), 11q13 and 17q11.2 (2), and 18q11.2 and 20q11.2 (2). Our study validated the ability of SKY to characterize in detail the chromosomal rearrangements in solid tumors and derived cell lines. Moreover, fluorescence in situ hybridization helped to identify the insertions, translocations, and homogeneously staining regions of MYC and CCND1 gene loci.

CONCLUSION: The non-random co-localization of certain cytogenetic bands suggests the importance of chromosomal translocations in gastric carcinogenesis, by serving as landmarks for the cloning of GC causing genes.

Application of multiplex fluorescence in situ hybridization in the cytogenetic analysis of primary gastric carcinoma

The different genetic alterations observed in diffuse and intestinal types of gastric cancer suggest that these two pathological types may represent different disease entities. We present two cases of primary gastric carcinoma, a well-differentiated intestinal type adenocarcinoma and a poorly differentiated diffuse type adenocarcinoma, both studied by a 24-color multiplex fluorescence in situ hybridization technique (M-FISH). The well-differentiated intestinal type adenocarcinoma exhibited fewer structural abnormalities with five noncomplex translocations, deletions of chromosomes 5q, 6q, and 17q and an i(8q). In the case of poorly differentiated diffuse carcinoma, structural abnormalities predominated and normal homologues were mostly absent. But there were also similarities between the two cases: translocations on 1p and 9p; structural abnormalities of chromosome 8 with consistent loss of 8p; structural abnormalities of 12q; partial loss of chromosome 17 and 18; and polysomy of chromosome 20. This study shows that M-FISH is valuable in identifying hidden structural abnormalities and could, therefore, be useful in the investigation of primary solid tumors.

An improved rapid procedure for fluorescence in situ hybridization that is applicable to intraoperative cancer cytodiagnosis

Fluorescence in situ hybridization (FISH) is among the most simple and useful methods for detecting numerical and structural aberration of chromosomes but it requires 12-24 h to complete. We devised a rapid FISH method that can be performed within 2 h. Here we describe the technique, which we have found to be extreme simple and as sensitive and specific as standard FISH, making it highly suitable for clinical use.

Sequential numerical changes of chromosomes 7 and 18 in diffuse-type stomach cancer cell lines: combined comparative genomic hybridization, fluorescence in situ hybridization, and ploidy analyses

Sequential changes of chromosomal copy number were analyzed retrospectively in five diffuse-type gastric cancer cell lines by comparative genomic hybridization (CGH), DNA cytometry, and fluorescence in situ hybridization (FISH) with centromeric and painting probes. By CGH, we found loss of 18q21 in all of the cell lines and gains of 7p11-q31, 20q, and 22 in four of the five cell lines. Actual copy numbers of chromosomes 7 and 18 were determined by FISH: disomy 18 with (partial) loss of 18q in the two DNA-diploid cell lines (AGS and MKN-45), trisomy 7 in MKN-45, disomy 18 and tetrasomy 7 with one-copy loss of 7p and one-copy gain of 7q tip in DNA-triploid HSC-39/40A, and trisomy 18 and hexasomy 7 with one-copy loss of 7q in DNA-tetraploid KATO-III. Because the DNA aneuploidy is thought to result through tetraploidization, and the duplicated chromosomal changes in DNA aneuploid tumors seem to precede tetraploidization, the duplicated gain of chromosome 7 and one-copy loss of 7q in KATO-III were inferred to have occurred before and after tetraploidization, respectively. Similarly, HSC-39/40A were inferred to be preceded by the DNA-diploid stage with disomy 7 and monosomy 18. As the loss of 18q21 and the gain of 7p11-q31 were inferred to have occurred already in the DNA diploid stage in at least four and two of the cell lines, respectively, the 18q21 loss may be more important than the 7q gain as an earlier event in the genesis of diffuse-type stomach cancer. The combined CGH, FISH, and ploidy analyses thus give us a clue to extract important earlier events from the chromosomal changes that were screened by CGH alone.

Cytogenetic study of 11 gastric adenocarcinomas

We describe the cytogenetic findings in 11 gastric cancer cases. Nine cases showed a variable number of numerical and structural aberrations, while two cases had a normal karyotype. The chromosomes most frequently involved are chromosome 3 in six cases, 6 in four cases, and 13 in three cases. They mainly exhibited structural aberrations. An additional segment on chromosome 3p was observed in three cases, while two cases had a del(3q). A der(5) chromosome resulting from a translocation between chromosomes 3 and 5 was observed in two cases. Both cases had also a del(6q), a der(12), and an add(17p) chromosome as common abnormalities. Deletion of 6q chromosome distal to band 6q21 was observed in three cases. Trisomy 8 as a sole anomaly was found in one case. Our cytogenetic findings are discussed in relation to the reported in the literature data.

Progression of signet ring cell carcinomas in the human stomach

BACKGROUND

Stomach cancers show various growth patterns. It remains to be clarified how this variability is related to the genetic changes that occur during tumor progression.

METHODS

To estimate the genetic changes from tumor ploidy, maps were made (using DNA cytofluorometry of metaphase cells in histologic sections) of 39 advanced signet ring cell carcinomas of the human stomach and correlated with tumor stage and the size of the primary mucosal lesion.

RESULTS

Aneuploid area and multipattern aneuploidy were particularly common in advanced cancers with primary mucosal lesions smaller than 2 cm in diameter, of which a large portion were predominantly aneuploid and already diffusely infiltrating. As the tumor stage advanced, the incidence of aneuploidy in the mucosal lesion increased, whereas predominantly aneuploid tumors were less common as primary mucosal lesions became larger. Purely diploid areas with an incidence of polyploidy as low as in early cancers were common in advanced cancers. In addition, there were diploid-appearing cancer cells that infiltrated diffusely and were accompanied by polyploid as often as aneuploid cells. Some of these were aneuploid at the chromosomal level.

CONCLUSIONS

In signet ring cell carcinoma, aneuploid cells show higher invasive activity toward the extramucosal part and may occur incidentally in originally diploid tumors, depending on the degree of genetic instability. An analysis of polyploidy is useful for differentiating cytometrically diploid (but actually, aneuploid) cells from diploid cells with minor genetic abnormalities.