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Microsatellite
Instability and Loss of Heterozygosity in Gastric Lymphoma |
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Ja-Mun Chong,
Masashi Fukayama, Yukiko Hayashi, Tsunekazu Hishima, Nobuaki Funata, Morio
Koike, Shoji Matsuya, Motoko Konishi, and Michiko Miyaki |
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Department
of Pathology (JMC, MF), Jichi Medical School, Tochigi; and Department of
Pathology (YH, TH, NF, MKoi), Tokyo Metropolitan Komagome Hospital; Department
of Pathology (SM), Kanto Teishin Hospital; and Department of Biochemistry
(MKon, MM), Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan |
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To evaluate the significance
of microsatellite instability (MI) and loss of heterozygosity (LOH) in the
development of gastric lymphoma, we examined 33 tissue-samples of 20 primary
gastric B-cell lymphomas (6 low-grade lymphomas of mucosa-associated lymphoid
tissue [MALT; 10 samples] and 14 diffuse large B-cell lymphomas [23 samples]).
MI and LOH were evaluated at 13 microsatellite loci. In MALT lymphoma, four
of six cases showed MI at one to two microsatellite loci (average 1.0 per
case, 0.8 per sample), whereas in diffuse B-cell lymphoma, all samples showed
MI at one to five microsatellite loci (average 2.4 per case, 2.7 per sample)
(p < 0.05 and p = 0.0001). MI at the c-myc gene locus was most frequent
in both types of gastric lymphomas (3 of 6 and 11 of 14 cases, respectively).
Regional heterogeneity of the MI pattern was observed in two of four cases
of MALT lymphoma and in four of five cases of diffuse B-cell lymphoma. On
the other hand, LOH was observed only in one MALT lymphoma and in three
diffuse B-cell lymphomas. Genetic instability may be an important mechanism
for the development and progression of gastric lymphoma. Frequent MI at
the c-myc locus might reflect an activated state and the importance of this
gene in mucosal lymphocytes of chronic gastritis. |
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