Construction and analysis of tree models for chromosomal classification of diffuse large B-cell lymphomas.
OBJECTIVE
To construct tree models for classification of diffuse large B-cell lymphomas (DLBCL) by chromosome copy numbers, to compare them with cDNA microarray classification, and to explore models of multi-gene, multi-step and multi-pathway processes of DLBCL tumorigenesis.


METHODS
Maximum-weight branching and distance-based models were constructed based on the comparative genomic hybridization (CGH) data of 123 DLBCL samples using the established methods and software of Desper et al. A maximum likelihood tree model was also used to analyze the data. By comparing with the results reported in literature, values of tree models in the classification of DLBCL were elucidated.


RESULTS
Both the branching and the distance-based trees classified DLBCL into three groups. We combined the classification methods of the two models and classified DLBCL into three categories according to their characteristics. The first group was marked by +Xq, +Xp, -17p and +13q; the second group by +3q, +18q and +18p; and the third group was marked by -6q and +6p. This chromosomal classification was consistent with cDNA classification. It indicated that -6q and +3q were two main events in the tumorigenesis of lymphoma.


CONCLUSIONS
Tree models of lymphoma established from CGH data can be used in the classification of DLBCL. These models can suggest multi-gene, multi-step and multi-pathway processes of tumorigenesis. Two pathways, -6q preceding +6q and +3q preceding +18q, may be important in understanding tumorigenesis of DLBCL. The pathway, -6q preceding +6q, may have a close relationship with the tumorigenesis of non-GCB DLBCL.
Jiang
Hui-Yong
HY
Department of General Surgery, General Hospital of Shenyang Military Region, Shenyang, China.
Huang
Zhong-Xi
ZX
Zhang
Xue-Feng
XF
Desper
Richard
R
Zhao
Tong
T
D002869:Chromosome Aberrations / Q000145:classification*; D004273:DNA, Neoplasm / Q000235:genetics; D003663:Decision Trees; D018628:Gene Dosage / Q000235:genetics; D020869:Gene Expression Profiling / Q000145:classification*; D006801:Humans; D016403:Lymphoma, Large B-Cell, Diffuse / Q000145:classification* / Q000235:genetics; D008954:Models, Biological; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis
D004273:DNA, Neoplasm