SPAG6 silencing induces autophagic cell death in SKM-1 cells via the AMPK/mTOR/ULK1 signaling pathway

Progress in the study of autophagy-related proteins affecting resistance to chemotherapeutic drugs in leukemia

Leukemia is a life-threatening malignant tumor of the hematopoietic system. Currently, the main treatment modalities are chemotherapy and hematopoietic stem cell transplantation. However, increased drug resistance due to decreased sensitivity of leukemia cells to chemotherapeutic drugs presents a major challenge in current treatments. Autophagy-associated proteins involved in autophagy initiation have now been shown to be involved in the development of various types of leukemia cells and are associated with drug resistance. Therefore, this review will explore the roles of autophagy-related proteins involved in four key autophagic processes: induction of autophagy and phagophore formation, phagophore extension, and autophagosome formation, on the development of various types of leukemias as well as drug resistance. Autophagy may become a promising therapeutic target for treating leukemia.

Integrated analysis of lncRNA, miRNA and mRNA expression profiles reveals regulatory pathways associated with pig testis function

Long noncoding RNA (lncRNA) and microRNA (miRNA) are known to play pivotal roles in mammalian testicular function and spermatogenesis. However, their impact on porcine male reproduction has yet to be well unraveled. Here, we sequenced and identified lncRNA and miRNA expressed in the testes of Chinese indigenous Banna mini-pig inbred line (BMI) and introduced Western Duroc (DU) and Large White (LW) pigs. By pairwise comparison (BMI vs DU, BMI vs LW, and DU vs LW), we found the gene expression differences in the testes between Chinese local pigs and introduced Western commercial breeds were more striking than those between introduced commercial breeds. Furthermore, we found 1622 co-differentially expressed genes (co-DEGs), 122 co-differentially expressed lncRNAs (co-DELs), 39 co-differentially expressed miRNAs (co-DEMs) in BMI vs introduced commercial breeds (DU and LW). Functional analysis revealed that these co-DEGs and co-DELs/co-DEMs target genes were enriched in male sexual function pathways, including MAPK, AMPK, TGF-β/Smad, Hippo, NF-kappa B, and PI3K/Akt signaling pathways. Additionally, we established 10,536 lncRNA-mRNA, 11,248 miRNA-mRNA pairs, and 62 ceRNA (lncRNA-miRNA-mRNA) networks. The ssc-miR-1343 had the most interactive factors in the ceRNA network, including 20 mRNAs and 3 lncRNAs, consisting of 56 ceRNA pairs. These factors played extremely important roles in the regulation of testis function as key nodes in the interactive regulatory network. Our results provide insight into the functional roles of lncRNAs and miRNAs in porcine testis and offer a valuable resource for understanding the differences between Chinese indigenous and introduced Western pigs.

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.

SPAG6 c.900 T>C affects boar semen quality and blood-testis barrier function by creating a new splice acceptor site

Sperm associated antigen 6 (SPAG6) acts as a scaffolding protein in the center of the flagellar axoneme and has an impact on the maturation of the motility of mammalian sperm flagella and the maintenance of sperm structure. In our previous research, SPAG6 c.900 T>C in exon 7 and exon 7 skipped transcript was identified by analyzing RNA-seq data of testicular tissues from 60 day (sexually immature) and 180 day (sexually mature) Large White boars. Herein, we found porcine SPAG6 c.900 T>C to be associated with semen quality traits in Duroc, Large White and Landrace pigs. SPAG6 c.900 C can generate a new splice acceptor site, inhibit the occurrence of SPAG6 exon 7 skipping to a certain extent, thereby promote the growth of Sertoli cells and maintain the normal blood-testis barrier function. This study provides new insights into the molecular regulation of spermatogenesis and a new genetic marker for the improvement of semen quality in pigs.

Biology of Cancer-Testis Antigens and Their Therapeutic Implications in Cancer

Tumour-specific antigens have been an area of interest in cancer therapy since their discovery in the middle of the 20th century. In the era of immune-based cancer therapeutics, redirecting our immune cells to target these tumour-specific antigens has become even more relevant. Cancer-testis antigens (CTAs) are a class of antigens with an expression specific to the testis and cancer cells. CTAs have also been demonstrated to be expressed in a wide variety of cancers. Due to their frequency and specificity of expression in a multitude of cancers, CTAs have been particularly attractive as cancer-specific therapeutic targets. There is now a rapid expansion of CTAs being identified and many studies have been conducted to correlate CTA expression with cancer and therapy-resistant phenotypes. Furthermore, there is an increasing number of clinical trials involving using some of these CTAs as molecular targets in pharmacological and immune-targeted therapeutics for various cancers. This review will summarise the current knowledge of the biology of known CTAs in tumorigenesis and the regulation of CTA genes. CTAs as molecular targets and the therapeutic implications of these CTA-targeted anticancer strategies will also be discussed.

A new machine learning method for cancer mutation analysis

It is complicated to identify cancer-causing mutations. The recurrence of a mutation in patients remains one of the most reliable features of mutation driver status. However, some mutations are more likely to happen than others for various reasons. Different sequencing analysis has revealed that cancer driver genes operate across complex pathways and networks, with mutations often arising in a mutually exclusive pattern. Genes with low-frequency mutations are understudied as cancer-related genes, especially in the context of networks. Here we propose a machine learning method to study the functionality of mutually exclusive genes in the networks derived from mutation associations, gene-gene interactions, and graph clustering. These networks have indicated critical biological components in the essential pathways, especially those mutated at low frequency. Studying the network and not just the impact of a single gene significantly increases the statistical power of clinical analysis. The proposed method identified important driver genes with different frequencies. We studied the function and the associated pathways in which the candidate driver genes participate. By introducing lower-frequency genes, we recognized less studied cancer-related pathways. We also proposed a novel clustering method to specify driver modules. We evaluated each driver module with different criteria, including the terms of biological processes and the number of simultaneous mutations in each cancer. Materials and implementations are available at: https://github.com/MahnazHabibi/MutationAnalysis.

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.

Comprehensive analysis of SPAG1 expression as a prognostic and predictive biomarker in acute myeloid leukemia by integrative bioinformatics and clinical validation

Background

Recently, an increasing number of studies have reported that sperm-associated antigen (SPAG) proteins play crucial roles in solid tumorigenesis, and may serve as potentially helpful biomarkers for cancer diagnosis and prognosis. However, very few studies systematically investigated the expression of SPAG family members and their clinical significance in acute myeloid leukemia (AML).

Methods

The expression of SPAGs and their prognostic significance in AML were determined by a systematic analysis on data gathered from public databases, and the results were validated in clinical samples.

Results

Using public data, we identified only increased SPAG1 expression negatively associated with survival in AML by Cox regression (P < 0.001) and Kaplan–Meier analysis (P < 0.001). The prognostic value of SPAG1 expression was further confirmed in other independent cohorts. Clinically, higher SPAG1 expression was significantly correlated with white blood cell counts (P = 0.014) and French–American–British (FAB) subtypes (P = 0.024). Moreover, higher SPAG1 expression was more common in + 8 patients (P = 0.034), rarely found with t(8;21) (P = 0.014), and correlated with FLT3 (P < 0.001) and DNMT3A mutations (P = 0.001). Despite these associations, multivariate analysis confirmed the independent prognostic value of SPAG1 expression in AML (P < 0.001). Notably, AML patients with higher SPAG1 expression may benefit from hematopoietic stem cell transplantation (HSCT), whereas patients with lower SPAG1 expression appeared less likely to benefit. Finally, we further validated that SPAG1 expression was significantly increased in newly diagnosed AML patients compared with normal controls (P < 0.001) and with AML patients who achieved complete remission (P < 0.001). Additionally, SPAG1 expression could act as a potentially helpful biomarker for the diagnosis and prognosis of AML (P < 0.001 and = 0.034, respectively).

Conclusions

Our findings demonstrated that SPAG1 overexpression may serve as an independent prognostic biomarker and may guide the choice between HSCT and chemotherapy in patients with AML.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01193-0.

[Effects of SPAG6 silencing and decitabine treatment on apoptosis and phosphatase and tensin homolog methylation in SKM-1 cells]

Objective: To investigate the effects of SPAG6 silencing and decitabine on apoptosis and phosphatase and tensin homolog (PTEN) methylation in SKM-1 cells in vitro and in vivo. Methods: SKM-1 cells were transfected with a lentiviral vector to silence the expression of SPAG6. Cell survival rate was detected by CCK8 after treatment with decitabine, and cell apoptosis was detected by flow cytometry. Protein expression and methylation of PTEN were detected using Western blot and merozoite surface protein (MSP) . An non-obese diabetic/severe combined inmunodeficiency disease (NOD/SCID) mice xenograft tumor model was established, and the apoptosis and PTEN expression of tumor tissue were observed through terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and immunohistochemistry (IHC) , respectively. Results: After lentivirus transfection, SPAG6 in the interference group was silenced successfully. CCK8 results indicated that the cell survival rate of SKM-1 cells treated with decitabine decreased. Flow cytometry showed that the apoptosis rate of cells treated with decitabine [ (17.35±3.37) %] was higher than that of the untreated group (5.09%±2.06%) and the apoptosis rate of the SPAG6 silencing combined with the decitabine treatment group was the highest [ (36.34±4.00) %]. After treatment with decitabine, the expression of DNMT1 decreased, while the expression of PTEN increased, and the promoter methylation degree of PTEN also decreased. Moreover, the increased protein level caused by PTEN demethylation was the most obvious in the SPAG6 in the interference shRNA group treated with decitabine. In NOD/SCID mice, the tumor volume of the decitabine group was significantly smaller than that of the placebo group, and the tumor volume of the SPAG6 silencing combined with the decitabine treatment group was the smallest. Additionally, the apoptosis rate was the highest (the positive ratio was 3.57±0.48) . Conclusion: SPAG6 silencing may enhance the apoptosis level and the effect of PTEN demethylation in SKM-1 cells and enhance the antitumor effect of decitabine in the NOD/SCID xenograft mouse model.

Aberrant expression of SPAG6 may affect the disease phenotype and serve as a tumor biomarker in BCR/ABL1-negative myeloproliferative neoplasms

Sperm-associated antigen 6 (SPAG6) is a newly identified cancer-testis antigen that has been revealed to contribute to the occurrence and development of various types of human cancer, such as ovarian, bladder, breast and lung cancer. However, to the best of our knowledge, the expression levels of SPAG6 in breakpoint cluster region (BCR)/ABL1-negative myeloproliferative neoplasms (MPNs) have not been investigated previously. Using reverse transcription-quantitative PCR and different tissue staining techniques, the present study revealed that SPAG6 was expressed by MPN cells, both at the mRNA and protein levels, and that nucleated erythroid precursors and megakaryocytes expressed the highest levels of SPAG6. In addition, SPAG6, which is known as a microtubule-associated protein, was found to exhibit nucleic, cytoplasmic or both cytoplasmic and nucleic subcellular localization patterns within the same patient or cell type; however, it did not always co-localize with β-tubulin. Furthermore, SPAG6 expression was revealed to be associated with fewer splenomegaly [P=0.015 for polycythemia vera (PV) and essential thrombocythemia (ET); and P=0.012 for primary myelofibrosis (PMF)] and myelofibrosis events (P=0.014 for PV and ET; and P=0.004 for PMF). In patients with PMF, upregulated expression levels of SPAG6 were also found to be associated with lower white blood cell counts (P=0.042) and lactate dehydrogenase levels (P=0.012), and higher hemoglobin levels (P=0.031) and platelet counts (P=0.025). In addition, the receiver operating characteristic curve analysis indicated that SPAG6 may be a potential biomarker for distinguishing MPN cases from healthy individuals. In conclusion, to the best of our knowledge, the present study is the first to report that aberrant SPAG6 expression may affect the disease phenotype and serve as a tumor biomarker in BCR/ABL1-negative MPNs.

Targeting acute myeloid leukemia cells by CD33 receptor-specific MoS2-based nanoconjugates

Acute myeloid leukemia (AML) is a highly aggressive type of cancer caused by the uncontrolled proliferation of undifferentiated myeloblasts, affecting the bone marrow and blood. Systemic chemotherapy is considered the primary treatment strategy; unfortunately, healthy cells are also affected to a large extent, leading to severe side effects of this treatment. Targeted drug therapies are becoming increasingly popular in modern medicine, as they bypass normal tissues and cells. Two-dimensional MoS₂-based nanomaterials have attracted attention in the biomedical field as promising agents for cancer diagnosis and therapy. Cancer cells typically (over)express distinctive cytoplasmic membrane-anchored or -spanning protein-based structures (e.g., receptors, enzymes) that distinguish them from healthy, non-cancerous cells. Targeting cancer cells via tumor-specific markers using MoS₂-based nanocarriers loaded with labels or drugs can significantly improve specificity and reduce side effects of such treatment. SKM-1 is an established AML cell line that has been employed in various bio-research applications. However, to date, it has not been used as the subject of studies on selective cancer targeting by inorganic nanomaterials. Here, we demonstrate an efficient targeting of AML cells using MoS₂nanoflakes prepared by a facile exfoliation route and functionalized with anti-CD33 antibody that binds to CD33 receptors expressed by SKM-1 cells. Microscopic analyses by confocal laser scanning microscopy supplemented by label-free confocal Raman microscopy proved that (anti-CD33)-MoS₂conjugates were present on the cell surface and within SKM-1 cells, presumably having been internalized via CD33-mediated endocytosis. Furthermore, the cellular uptake of SKM-1 specific (anti-CD33)-MoS₂conjugates assessed by flow cytometry analysis was significantly higher compared with the cellular uptake of SKM-1 nonspecific (anti-GPC3)-MoS₂conjugates. Our results indicate the importance of appropriate functionalization of MoS₂nanomaterials by tumor-recognizing elements that significantly increase their specificity and hence suggest the utilization of MoS₂-based nanomaterials in the diagnosis and therapy of AML.

Cancer/testis antigens: from serology to mRNA cancer vaccine

Cancer/testis antigens (CTAs) are a group of tumor antigens expressed in numerous cancer tissues, as well as in the testis and placental tissues. There are over 200 CTAs supported by serology and expression data. The expression patterns of CTAs reflect the similarities between the processes of gametogenesis and tumorigenesis. It is notable that CTAs are highly expressed in three types of cancers (lung cancer, bladder cancer, and skin cancer), all of which have a metal etiology. Here, we review the expression, regulation, and function of CTAs and their translational prospects as cancer biomarkers and treatment targets. Many CTAs are highly immunogenic, tissue-specific, and frequently expressed in cancer tissues but not under physiological conditions, rendering them promising candidates for cancer detection. Some CTAs are associated with clinical outcomes, so they may serve as prognostic biomarkers. A small number of CTAs are membrane-bound, making them ideal targets for chimeric antigen receptor (CAR) T cells. Mounting evidence suggests that CTAs induce humoral or cellular immune responses, providing cancer immunotherapeutic opportunities for T-cell receptors (TCRs), CAR T cell, antibody-based therapy and peptide- or mRNA-based vaccines. Indeed, CTAs are the dominating non-mutated targets in mRNA cancer vaccine development. Clinical trials on CTA TCR and vaccines have shown effectiveness, safety, and tolerance, but these successes are limited to a small number of patients. In-depth studies on CTA expression and function are needed to improve CTA-based immunotherapy.

SPAG6-silencing enhances decitabine-induced apoptosis and demethylation of PTEN in SKM-1 cells and in a xenograft mouse model

Myelodysplastic syndromes (MDS) are a group of malignant diseases that are characterized by disordered hematopoiesis with a high risk of transforming into leukemia. In the present study, SPAG6-knockdown and decitabine (DAC) treatment resulted in a decreased DNA methyltransferases and methyl-CpG-binding domain protein expression. In addition, DAC and LBH589 were shown to promote apoptosis in SKM-1 cells, and SPAG6-knockdown to enhance the pro-apoptotic effect of DAC. DAC could reduce PTEN methylation and increase PTEN expression in SKM-1 cells. SPAG6-knockdown and LBH589 treatment could increase DAC-mediated demethylation of PTEN promoter. Finally, a mouse model was constructed, and an enhanced efficacy of DAC following SPAG6-knockdown was confirmed in vivo. In conclusion, DAC-mediated apoptosis and PTEN promoter demethylation may be synergistically enhanced by SPAG6-silencing. Therefore, in the present study it was indicated that SPAG6 may be a potential target for demethylation therapy in MDS.