Electron microscopic detection of periodate reactive complex carbohydrates in human T and B lymphocytes

Lung adenocarcinoma-intrinsic GBE1 signaling inhibits anti-tumor immunity

Background

Changes in glycogen metabolism is an essential feature among the various metabolic adaptations used by cancer cells to adjust to the conditions imposed by the tumor microenvironment. Our previous study showed that glycogen branching enzyme (GBE1) is downstream of the HIF1 pathway in hypoxia-conditioned lung cancer cells. In the present study, we investigated whether GBE1 is involved in the immune regulation of the tumor microenvironment in lung adenocarcinoma (LUAD).

Methods

We used RNA-sequencing analysis and the multiplex assay to determine changes in GBE1 knockdown cells. The role of GBE1 in LUAD was evaluated both in vitro and in vivo.

Results

GBE1 knockdown increased the expression of chemokines CCL5 and CXCL10 in A549 cells. CD8 expression correlated positively with CCL5 and CXCL10 expression in LUAD. The supernatants from the GBE1 knockdown cells increased recruitment of CD8⁺ T lymphocytes. However, the neutralizing antibodies of CCL5 or CXCL10 significantly inhibited cell migration induced by shGBE1 cell supernatants. STING/IFN-I pathway mediated the effect of GBE1 knockdown for CCL5 and CXCL10 upregulation. Moreover, PD-L1 increased significantly in shGBE1 A549 cells compared to those in control cells. Additionally, in LUAD tumor tissues, a negative link between PD-L1 and GBE1 was observed. Lastly, blockade of GBE1 signaling combined with anti-PD-L1 antibody significantly inhibited tumor growth in vivo.

Conclusions

GBE1 blockade promotes the secretion of CCL5 and CXCL10 to recruit CD8⁺ T lymphocytes to the tumor microenvironment via the IFN-I/STING signaling pathway, accompanied by upregulation of PD-L1 in LUAD cells, suggesting that GBE1 could be a promising target for achieving tumor regression through cancer immunotherapy in LUAD.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-1027-x) contains supplementary material, which is available to authorized users.

Glycogen metabolism has a key role in the cancer microenvironment and provides new targets for cancer therapy

Metabolic reprogramming is a hallmark of cancer cells and contributes to their adaption within the tumour microenvironment and resistance to anticancer therapies. Recently, glycogen metabolism has become a recognised feature of cancer cells since it is upregulated in many tumour types, suggesting that it is an important aspect of cancer cell pathophysiology. Here, we provide an overview of glycogen metabolism and its regulation, with a focus on its role in metabolic reprogramming of cancer cells under stress conditions such as hypoxia, glucose deprivation and anticancer treatment. The various methods to detect glycogen in tumours in vivo as well as pharmacological modulators of glycogen metabolism are also reviewed. Finally, we discuss the therapeutic value of targeting glycogen metabolism as a strategy for combinational approaches in cancer treatment.

Myeloid and erythroid lineage expression of haemopoietic progenitors derived from an abnormal clone in erythroleukaemia

To clarify the lineage involvement of haemopoietic progenitor cells in erythroleukaemia, the morphology and chromosomes of single colonies from a patient with erythroleukaemia were analysed simultaneously. The cytogenetic analysis of bone marrow cells revealed two clones; 44,XY,-7,-12,-17, del (5)(q31), +Mar and 43,XY,-7,-12,-17,-19,del(5)(q31),+Mar. Of 40 metaphases examined, there were 34 and six of these clones, respectively. Bone marrow mononuclear cells were plated at 5 X 10(4)/ml in methylcellulose medium containing phytohaemagglutinin-stimulated leucocyte conditioned medium and erythropoietin. Seventeen colonies, i.e. nine blast cell colonies, four myeloid (Sudan black B-positive) colonies, and four erythroid (benzidine-positive) colonies contained analysable metaphases, yielding 102 metaphases in total. Except for chromosome random loss, the karyotype within a colony remained constant. All three types of colonies showed an abnormal clone; 44,XY,-7,-12,-17,del(5)(q31),+Mar. From these findings, it is concluded that myeloid and erythroid lineages in erythroleukaemia were derived from the same abnormal clone.

Ultrastructural evaluation of periodate-reactive glycoconjugates in human leukaemia cells

Periodate-reactive glycoconjugates in human leukaemic cells were examined electron microscopically by the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) method. Granules in ALL cells were classified into 4 types based on PA-TCH-SP staining features. Abnormal granules containing glycogen were observed only in children with treatment-resistant ALL. Cytoplasmic granules in leukaemic cells of patients with AML and acute monocytic leukaemia exhibited moderate reactivity. The distribution pattern of glycogen in the cytoplasm of leukaemic cells was classified into 3 types, one lacking glycogen, one containing small glycogen particles scattered throughout cytoplasm, and one showing clusters of glycogen particles. Cells with glycogen clusters were observed in ALL cells and in erythroblasts from patients with erythroleukaemia. PA-TCH-SP reactivity was detected in the rough endoplasmic reticulum in acute promyelocytic leukaemia but not in ALL or other types of AML. Megakaryoblasts in megakaryocytic crisis of chronic myelogenous leukaemia exhibited characteristic PA-TCH-SP reactivity similar to that of normal megakaryocytes.

Ultracytochemistry of glycogen particles in human erythroblasts. Semiquantitative observation

We examined the fine structural distribution of glycogen particles in the cells of the erythrocyte series from thirty individuals with or without hematological disorders using the periodic acid-thiocarbo hydrazide-silver proteinate (PA-TCH-SP) technique, which is known to extend PAS staining to the ultrastructural level. In diseases exhibiting dyserythropoiesis, such as refractory anemia with excess of blasts (RAEB) and juvenile chronic myelocytic leukemia (JCML), glycogen particles remarkably increased. In diseases showing hypererythropoiesis such as iron deficiency anemia, hemolytic anemia, or in cells obtained from very small premature infants, an increase in glycogen particles was observed in most cases. Compared to the PAS staining technique, which also utilizes the periodic acid reaction, the PA-TCH-SP technique appears to be more sensitive for visualizing glycogen particles in PAS negative cells, in addition to its capability of demonstrating the distribution of periodate reactive substance at the fine structural level.