In a long-term humanized mouse model following HTLV-1 infection, the gene expression array data exhibited an apparent increase in A3B and CADM1, which are indicators of ATL.
These results suggested that the ectopic expression of TSLC1 could provide a novel marker for acute-type ATL and may participate in tissue invasion, a characteristic feature of the malignant ATL cells.
Our results indicate that the percentage of the CD4<sup>+</sup> CADM1<sup>+</sup> population predicts clinical disease progression: G1 and G2 cases, including AC cases, are stable and considered to be at low risk; G3 cases, including advanced AC cases and smoldering-type ATL cases based on the Shimoyama criteria, are considered to have intermediate risk; and G4 cases, which are mainly indolent ATL cases, are unstable and at high risk of acute transformation.
The tumor suppressor lung cancer 1 (TSLC1) gene was previously identified as a novel cell surface marker for ATL, and this study demonstrated the involvement of TSLC1 expression in tumor growth and organ infiltration of ATL cells.
TSLC1/IGSF4 is ectopically expressed in adult T-cell leukemia (ATL) cells, providing not only a diagnostic marker for ATL, but also a possible therapeutic target against its invasion.
In HTLV-1-infected T-cells, CADM1 expression is dependent on HTLV-1/Tax through activation of canonical and non-canonical NF-κB; however, in ATLL cells with frequent loss of Tax expression, the activation of canonical NF-κB only enhances the CADM1 expression.
Thus, detection of CD4(+)CADM1(+) cells in the peripheral blood, measurement of serum levels of soluble CADM1 and immunohistochemical detection of CADM1 in lymphomas would be a useful set of markers for disease progression in ATLL and may aid in both the early diagnosis and measurement of treatment efficacy for ATLL.
SPRi analysis identified a new interaction between CADM1 and CADM4, where this heterophilic interaction was shown to be involved in morphological spreading of adult T-cell leukemia (ATL) cells expressing CADM1 when incubated on CADM4-coated glass.
Cell adhesion molecule 1 gene (CADM1), which was initially identified as a tumor suppressor gene in human non-small cell lung cancer, has been reported as a diagnostic marker for adult T-cell leukemia/lymphoma.