Adult T-cell leukemia/lymphoma complicated by Pneumocystis pneumonia in a non-endemic area

Adult T-cell leukemia/lymphoma (ATLL) is a human T-cell leukemia virus type 1-inducing unevenly-distributed T-cell malignancy, which is often complicated by opportunistic infections. Here, we discuss the case of a 75-year-old woman presenting with Pneumocystis pneumonia (PCP) who was subsequently diagnosed with ATLL in Tokyo, a non-endemic area of ATLL. In addition to the elevated soluble interleukin-2 receptor and the detection of flower cells in the screening blood test, the high-resolution computed tomography findings, atypical of PCP, were clues to the diagnosis of ATLL. ATLL should be considered as an underlying disease when patients present with PCP, even in non-endemic areas.

Pathogenicity and virulence of human T lymphotropic virus type-1 (HTLV-1) in oncogenesis: adult T-cell leukemia/lymphoma (ATLL)

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive malignancy of CD4⁺ T lymphocytes caused by human T lymphotropic virus type-1 (HTLV-1) infection. HTLV-1 was brought to the World Health Organization (WHO) and researchers to address its impact on global public health, oncogenicity, and deterioration of the host immune system toward autoimmunity. In a minority of the infected population (3-5%), it can induce inflammatory networks toward HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), or hijacking the infected CD4⁺ T lymphocytes into T regulatory subpopulation, stimulating anti-inflammatory signaling networks, and prompting ATLL development. This review critically discusses the complex signaling networks in ATLL pathogenesis during virus-host interactions for better interpretation of oncogenicity and introduces the main candidates in the pathogenesis of ATLL. At least two viral factors, HTLV-1 trans-activator protein (TAX) and HTLV-1 basic leucine zipper factor (HBZ), are implicated in ATLL manifestation, interacting with host responses and deregulating cell signaling in favor of infected cell survival and virus dissemination. Such molecules can be used as potential novel biomarkers for ATLL prognosis or targets for therapy. Moreover, the challenging aspects of HTLV-1 oncogenesis introduced in this review could open new venues for further studies on acute leukemia pathogenesis. These features can aid in the discovery of effective immunotherapies when reversing the gene expression profile toward appropriate immune responses gradually becomes attainable.

Molecular insight into the study of adult T-cell leukemia/lymphoma (ATLL): Ten-year studies on HTLV-1 associated diseases in an endemic region

The outcome of successful infection, including human T-cell leukemia virus type 1 (HTLV-1), is determined by the interactions between the host and the infectious agent. Ten years of work on HTLV-1-associated diseases in an endemic region of Iran have been critically compared in the present study. The outstanding findings of RNA-seq, system biology analysis, and gene expression measurements on adult T-cell leukemia/lymphoma (ATLL) and enzootic bovine leukosis(EBL) in our lab encouraged us to investigate the significant role of oncogenes in the ATLL malignancy. Most studies assessed such interactions by the proviral load (PVL), Tax, and HBZ regulatory proteins in HTLV-1 and the host's immunological and cell cycle factors. The current study is a comprehensive comparing view of our previously published and unpublished results investigating the HTLV-1-host interactions leading to the transformation of the infected cell. The main focus has been on the essential proteins implicated in the virus dissemination, cell survival, and proliferation of infected cells toward leukemia development and progression. Similar to its homolog BLV-AS-1-2 in EBL, the HTLV-1-HBZ is a pivotal factor in the maintenance and progression of the ATLL. In addition, the inappropriate activities of the PI3K/Akt pathway, BRCAs, and RAD51 in the DNA repair system, which are orchestrating many other immortalization pathways, might be the central factors in the manifestation of ATLL. HTLV-1-HBZ and the host PI3K/Akt pathway, BCAs, and RAD51 could be suggested as influential targets for the prognosis and proper therapy of ATLL.

Endoscopic and clinicopathological characteristics of gastrointestinal adult T-cell leukemia/lymphoma

Background

Adult T-cell leukemia/lymphoma (ATLL) frequently involves the gastrointestinal (GI) tract, and patients mainly show an aggressive clinical course despite of intensive cytotoxic treatments. We investigated the characteristic clinicopathological and endoscopic features of GI ATLL.

Methods

This was a retrospective analysis of 61 GI tract lesions in 54 ATLL patients.

Results

Thirty-six (67%) patients were classified as having lymphoma-type ATLL and 18 (33%) patients were classified as having acute-type with leukemic changes. Examined ATLL lesions in the stomach and intestine (small intestine and colorectum) were 40 (66%) and 21 (34%), respectively. Gastric ATLL lesions were frequently found in the lymphoma-type (29/38; 76%) compared with the acute-type lesions (11/23; 48%; P=0.023). Intestinal ATLL lesions were frequent in the acute-type (12/23; 52%) compared with the lymphoma-type lesions (9/38; 24%; P=0.023). Endoscopically, tumor-forming type lesions were significantly more frequent in lymphoma-type ATLL lesions (29/38 lesions; 76%) compared with acute-type lesions (10/23; 44%; P=0.0096). The superficial spreading-type was significantly more frequent in acute-type lesions (12/23 lesions; 52%) compared with lymphoma-type lesions (3/38; 8%; P=0.0003). Additionally, gastropathy-, enteropathy-, or proctocolitis-like lesions were distinct features, mainly in the acute type (9/23 lesions; 39%). Twenty three of 39 tumor-forming-type lesions (59%) were significantly composed of pleomorphic or anaplastic large cell lymphoma, and 13 of 15 superficial spreading-type lesions (87%) were significantly composed of pleomorphic medium-sized cells (P=0.007, in each). Six patients (11%) who were estimated as having primary GI ATLL based on restricted clinical stages, showed a significantly better overall survival (OS) compared with the 48 advanced-stage patients (P=0.017). Twenty patients with solitary tumor-forming-type lesions showed a significantly better OS than 17 patients with the multiple tumor-forming-type (P=0.015) and five with the mucosal-thickening-type lesions (P=0.04). Twenty-six patients with pleomorphic or anaplastic large cell ATLL showed a significantly better prognosis compared with 28 patients with pleomorphic medium-sized ATLL (P=0.034).

Conclusions

ATLL predominantly involves the stomach. Leukemic behavior of ATLL had a large influence on the tumor location and endoscopic features of GI tract lesions. Gastropathy-, enteropathy-, and proctocolitis-like lesions showed additional distinct characteristics. Primary GI ATLL in the early clinical stages, solitary tumor-forming-type lesions and large tumor cells showed better prognostic factors than other factors, respectively.

WRN-targeted therapy using inhibitors NSC 19630 and NSC 617145 induce apoptosis in HTLV-1-transformed adult T-cell leukemia cells

Background

Human T-cell leukemia virus type 1 (HTLV-1) infection is associated with adult T-cell leukemia/lymphoma (ATLL), a lymphoproliferative malignancy with a dismal prognosis and limited therapeutic options. Recent evidence shows that HTLV-1-transformed cells present defects in both DNA replication and DNA repair, suggesting that these cells might be particularly sensitive to treatment with a small helicase inhibitor. Because the “Werner syndrome ATP-dependent helicase” encoded by the WRN gene plays important roles in both cellular proliferation and DNA repair, we hypothesized that inhibition of WRN activity could be used as a new strategy to target ATLL cells.

Methods

Our analysis demonstrates an apoptotic effect induced by the WRN helicase inhibitor in HTLV-1-transformed cells in vitro and ATL-derived cell lines. Inhibition of cellular proliferation and induction of apoptosis were demonstrated with cell cycle analysis, XTT proliferation assay, clonogenic assay, annexin V staining, and measurement of mitochondrial transmembrane potential.

Results

Targeted inhibition of the WRN helicase induced cell cycle arrest and apoptosis in HTLV-1-transformed leukemia cells. Treatment with NSC 19630 (WRN inhibitor) induces S-phase cell cycle arrest, disruption of the mitochondrial membrane potential, and decreased expression of anti-apoptotic factor Bcl-2. These events were associated with activation of caspase-3-dependent apoptosis in ATL cells. We identified some ATL cells, ATL-55T and LMY1, less sensitive to NSC 19630 but sensitive to another WRN inhibitor, NSC 617145.

Conclusions

WRN is essential for survival of ATL cells. Our studies suggest that targeting the WRN helicase with small inhibitors is a novel promising strategy to target HTLV-1-transformed ATL cells.