Measurable Residual Disease Monitoring of SPAG6, ST18, PRAME, and XAGE1A Expression in Peripheral Blood May Detect Imminent Relapse in Childhood Acute Myeloid Leukemia

Targeting PRAME for acute myeloid leukemia therapy

Despite significant progress in targeted therapy for acute myeloid leukemia (AML), clinical outcomes are disappointing for elderly patients, patients with less fit disease characteristics, and patients with adverse disease risk characteristics. Over the past 10 years, adaptive T-cell immunotherapy has been recognized as a strategy for treating various malignant tumors. However, it has faced significant challenges in AML, primarily because myeloid blasts do not contain unique surface antigens. The preferentially expressed antigen in melanoma (PRAME), a cancer-testis antigen, is abnormally expressed in AML and does not exist in normal hematopoietic cells. Accumulating evidence has demonstrated that PRAME is a useful target for treating AML. This paper reviews the structure and function of PRAME, its effects on normal cells and AML blasts, its implications in prognosis and follow-up, and its use in antigen-specific immunotherapy for AML.

SPAG6 regulates cell proliferation and apoptosis via TGF-β/Smad signal pathway in adult B-cell acute lymphoblastic leukemia

Adult B-cell acute lymphoblastic leukemia (B-ALL) prognosis remains unsatisfactory, and searching for new therapeutic targets is crucial for improving patient prognosis. Sperm-associated antigen 6 (SPAG6), a member of the cancer-testis antigen family, plays an important role in tumors, especially hematologic tumors; however, it is unknown whether SPAG6 plays a role in adult B-ALL. In this study, we demonstrated for the first time that SPAG6 expression was up-regulated in the bone marrow of adult B-ALL patients compared to healthy donors, and expression was significantly reduced in patients who achieved complete remission (CR) after treatment. In addition, patients with high SPAG6 expression were older (≥ 35 years; P = 0.015), had elevated white blood cell counts (WBC > 30 × 109/L; P = 0.021), and a low rate of CR (P = 0.036). We explored the SPAG6 effect on cell function by lentiviral transfection of adult B-ALL cell lines BALL-1 and NALM-6, and discovered that knocking down SPAG6 significantly inhibited cell proliferation and promoted apoptosis. We identified that SPAG6 knockdown might regulate cell proliferation and apoptosis via the transforming growth factor-β (TGF-β)/Smad signaling pathway.

Upregulated SPAG6 promotes acute myeloid leukemia progression through MYO1D that regulates the EGFR family expression

Chromosomal aberrations and gene mutations have been considered to be the major reasons for high recurrence rates and poor survival among acute myeloid leukemia (AML) patients. However, the underlying molecular mechanism of AML gene mutation remains largely unclear. Here, we show that SPAG6 (sperm-associated antigen 6), one of the most markedly increased SPAG genes in AML, significantly contributed to the proliferation and migration of leukemic cells. SPAG6 was highly expressed in AML, and its upregulation was negatively correlated with the prognosis of the disease. In vitro, SPAG6 promoted the proliferation and migration of leukemia cells and promoted cell cycle progression from the G1 phase to the S phase. In vivo, low expression of SPAG6 reduced the proliferation and infiltration of leukemia cells and prolonged the survival of xenograft tumor mice. Furthermore, immunoprecipitation and mass spectrometry analysis showed that SPAG6 interacts with MYO1D (myosin 1D). Specifically, overexpression of SPAG6 promoted the translocation of MYO1D into the cell membrane, thus upgrading the expression level of the EGFR family and thereby promoting the progression of AML. Overall, our study found that SPAG6 combined with MYO1D and translocated MYO1D from the cytosol to the cytomembrane, which induced the PI3K (phosphoinositide 3-kinase)/AKT (protein kinase B) signaling and ERK (extracellular signal-regulated kinase) signaling pathway to regulate the growth and prognosis of AML. SPAG6 may become a new target gene for the treatment of AML.