ALG3 predicts poor prognosis and increases resistance to anti-PD-1 therapy through modulating PD-L1 N-link glycosylation in TNBC.

OBJECTIVE: The aim of this study was to assess the prognostic significance of α-1,3-mannitrotransferase (ALG3) in triple-negative breast cancer (TNBC) and investigate its impact and potential mechanism on the efficacy of anti-PD-1 therapy. METHODS: Bioinformatics analysis was used to examine the expression of ALG3 in cancer patients using UACLAN and other databases. The associations of the ALG3 gene and the clinicopathological features of breast cancer were examined with bc-GenExMiner database. Correlation between ALG3 expression and survival was further established utilizing the Kaplan-Meier Plotter database. Immunohistochemistry (IHC) was used to analyze the expression of ALG3 in cohort of breast cancer patients from Hubei cancer hospital to confirmed the prognostic value of ALG3 in TNBC. The effect of ALG3 on the levels of infiltrating immune cells was also analyzed. And the mutation module within cBioPortal was utilized to visualize ALG3 mutations in BRCA. The CRISPR/Cas9 technique was used to establish ALG3 low-expression TNBC cell lines. Influence of ALG3 expression on cancer cell proliferation and chemotherapeutic responsiveness was scrutinized in vitro. Animal models were constructed to evaluate the alteration of tumor sensitivity to anti-PD-1 therapy with decreased ALG3 expression. And flow cytometry and IHC were used to investigate the tumor immune microenvironment. Association of PD-L1 Glycosylation and ALG3 expression were also investigated by western blot. RESULTS: ALG3 expression was elevated in TNBC and was strikingly linked to unfavorable clinical features such as lymphatic node metastasis, high NPI, advanced stage and age, etc. Furthermore, high ALG3 expression was associated with shorter OS in TNBC patients. Mechanistically, ALG3 expression was negatively correlated with the infiltration of CD8+ T cells, CD4+ T cells, and NK cells. ALG3-KO cells had increased sensitivity to chemotherapeutic agents. In animal models, the volume of ALG3-KO tumors was lower than the control group with immunotherapy. ALG3-KO tumors showed an increased proportion of CD8+ T cells, while a decreased proportion of regulatory T cells and M2-type macrophages. The expression level of PD-L1 protein was not affected by ALG3 level, but the glycosylation level was significantly decreased in tumor. Similarly, the glycosylation level of PD-L1 is reduced in ALG3-KO cell in vitro. Additionally, ALG3 knockout lead to reduced tolerance of tumor cells to IFN-γ, thereby enhancing the efficacy of immunotherapy. CONCLUSION: ALG3 is a potential biomarker for poor prognosis of TNBC and may reduce the efficacy of immunotherapy by modulating the tumor microenvironment and glycosylation of PD-L1.

Deep pan-cancer analysis and multi-omics evidence reveal that ALG3 inhibits CD8+ T cell infiltration by suppressing chemokine secretion and is associated with 5-fluorouracil sensitivity.

BACKGROUND: α-1,3-mannosyltransferase (ALG3) holds significance as a key member within the mannosyltransferase family. Nevertheless, the exact function of ALG3 in cancer remains ambiguous. Consequently, the current research aimed to examine the function and potential mechanisms of ALG3 in various types of cancer. METHODS: Deep pan-cancer analyses were conducted to investigate the expression patterns, prognostic value, genetic variations, single-cell omics, immunology, and drug responses associated with ALG3. Subsequently, in vitro experiments were executed to ascertain the biological role of ALG3 in breast cancer. Moreover, the link between ALG3 and CD8+ T cells was verified using immunofluorescence. Lastly, the association between ALG3 and chemokines was assessed using qRT-PCR and ELISA. RESULTS: Deep pan-cancer analysis demonstrated a heightened expression of ALG3 in the majority of tumors based on multi-omics evidence. ALG3 emerges as a diagnostic and prognostic biomarker across diverse cancer types. In addition, ALG3 participates in regulating the tumor immune microenvironment. Elevated levels of ALG3 were closely linked to the infiltration of bone marrow-derived suppressor cells (MDSC) and CD8+ T cells. According to in vitro experiments, ALG3 promotes proliferation and migration of breast cancer cells. Moreover, ALG3 inhibited CD8+ T cell infiltration by suppressing chemokine secretion. Finally, the inhibition of ALG3 enhanced the responsiveness of breast cancer cells to 5-fluorouracil treatment. CONCLUSION: ALG3 shows potential as both a prognostic indicator and immune infiltration biomarker across various types of cancer. Inhibition of ALG3 may represent a promising therapeutic strategy for tumor treatment.

Deficient glycan extension and endoplasmic reticulum stresses in ALG3-CDG.

ALG3-CDG is a rare congenital disorder of glycosylation (CDG) with a clinical phenotype that includes neurological manifestations, transaminitis, and frequent infections. The ALG3 enzyme catalyzes the first step of endoplasmic reticulum (ER) luminal glycan extension by adding mannose from Dol-P-Man to Dol-PP-Man5GlcNAc2 (Man5) forming Dol-PP-Man6. Such glycan extension is the first and fastest cellular response to ER stress, which is deficient in ALG3-CDG. In this study, we provide evidence that the unfolded protein response (UPR) and ER-associated degradation activities are increased in ALG3-CDG patient-derived cultured skin fibroblasts and there is constitutive activation of UPR mediated by the IRE1-α pathway. In addition, we show that N-linked Man3-4 glycans are increased in cellular glycoproteins and secreted plasma glycoproteins with hepatic or non-hepatic origin. We found that like other CDGs such as ALG1- or PMM2-CDG, in transferrin, the assembling intermediate Man5 in ALG3-CDG, are likely further processed into a distinct glycan, NeuAc1Gal1GlcNAc1Man3GlcNAc2, probably by Golgi mannosidases and glycosyltransferases. We predict it to be a mono-antennary glycan with the same molecular weight as the truncated glycan described in MGAT2-CDG. In summary, this study elucidates multiple previously unrecognized biochemical consequences of the glycan extension deficiency in ALG3-CDG which will have important implications in the pathogenesis of CDG.

Comprehensive analysis of ALG3 in pan-cancer and validation of ALG3 as an onco-immunological biomarker in breast cancer.

ALG3 has significant modulatory function in the process of tumor development. Yet how ALG3 involves in the advancement of different malignancies isn't fully understood. We performed a pan-cancer assessment on ALG3 utilizing datasets from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) to examine its tumor-related roles across malignancies and its link to particular molecules and cells in the tumor microenvironment (TME). Furthermore, we focused on breast cancer to examine the influence of ALG3-mediated signaling pathways and intercellular interactions in the advancement of tumors. The biological effects of ALG3 were verified by breast cancer cells. Enhanced ALG3 expression was discovered to be substantially linked to patients' grim prognoses in a number of malignancies. Furthermore, the expression of ALG3 in the TME was linked to the infiltration of stromal and immune cells, and ALG3-related immune checkpoints, TMB, and MSI were also discovered. We also discovered that cancer patients having a high level of ALG3 exhibited a lower probability of benefiting from immunotherapy. Furthermore, our research found that KEGG enrichment, single-cell RNA and spatial sequencing analyses were effective in identifying key signaling pathways in ALG3-associated tumor growth. In vitro, knockdown of ALG3 could decrease the proliferation of breast cancer cells. In summary, our research offers a comprehensive insight into the advancement of tumors under the mediation of ALG3. ALG3 appears to be intimately associated with tumor development in the TME. ALG3 might be a viable treatment target for cancer therapy, particularly in the case of breast cancer.

Identification of ALG3 as a potential prognostic biomarker in lung adenocarcinoma.

Background: The abnormal expression of Alpha-1,3-mannosyltransferase (ALG3) has been implicated in tumor promotion. However, the clinical significance of ALG3 in Lung Adenocarcinoma (LUAD) remains poorly understood. Therefore, we aimed to assess the prognostic value of ALG3 and its association with immune infiltrates in LUAD. Methods: The transcriptional expression profiles of ALG3 were obtained from the Cancer Genome Atlas (TCGA), comparing lung adenocarcinoma tissue with normal tissues. To determine the prognostic significance of AGL3, Kaplan-Meier plotter, and Cox regression analysis were employed. Logistic regression was utilized to analyze the association between ALG3 expression and clinical characteristics. Additionally, a receiver operating characteristic (ROC) curve and a nomogram were constructed. To explore the underlying mechanisms, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and gene set enrichment analysis (GSEA) was conducted. The relationship between AGL3A mRNA expression and immune infiltrates was investigated using the tumor immune estimation resource (TIMER) and tumor-immune system interaction database (TISIDB). Furthermore, an in vitro experiment was performed to assess the impact of ALG3 mRNA on lung cancer stemness abilities and examine key signaling pathway proteins. Results: Our results revealed the ALG3 mRNA and protein expression in patients with LUAD was much higher than that in adjacent normal tissues. High expression of ALG3 was significantly associated with N stage (N0, HR = 1.98, P = 0.002), pathological stage (stage I, HR = 2.09, P = 0.003), and the number of pack years (<40, HR = 2.58, P = 0.001). Kaplan-Meier survival analysis showed that high expression of ALG3 was associated with poor overall survival (P < 0.001), disease-free survival (P < 0.001), and progression-free interval (P = 0.007). Through multivariate analysis, it was determined that elevated ALG3 expression independently impacted overall survival (HR = 1.325, P = 0.04). The Tumor Immune Estimation Resource discovered a link between ALG3 expression and tumor-infiltrating immune cells in LUAD. Additionally, ROC analysis proved that ALG3 is a reliable diagnostic marker for LUAD (AUC:0.923). Functional pathways analysis identified that ALG3 is negatively correlated with FAT4. We performed qRT-PCR to assess that knockdown ALG3 expression significantly upregulated FAT4 expression. Spheroid assay and flow cytometry analysis results showed that downregulated of ALG3 inhibited H1975 cell line stemness. Western blot analysis revealed that decreased ALG3 inhibited the YAP/TAZ signal pathway. Conclusion: High expression of ALG3 is strongly associated with poor prognosis and immune infiltrates in LUAD.

ALG3 Promotes Peritoneal Metastasis of Ovarian Cancer through Increasing Interaction of α1,3-mannosylated uPAR and ADAM8.

Peritoneal metastasis is the main cause of poor prognoses and high mortality in ovarian cancer patients. Abnormal protein glycosylation modification is associated with cancer malignancy. Elevated α1,3-mannosyltransferase 3 (ALG3), which catalyzes the α1,3-mannosylation of glycoproteins, has been found in some malignant tumors. However, the pathological significance of ALG3 and its regulatory mechanism in ovarian cancer metastasis is unclear. The results showed that the level of ALG3/α1,3-mannosylation was higher in human ovarian cancer tissues compared with normal ovarian tissues, as measured by Lectin chip, Western blot and Lectin blot analyses, as well as ovarian tissue microarray analysis. ALG3 was also correlated with the poor prognosis of ovarian cancer patients, according to survival analysis. The downregulation of ALG3 decreased the proliferation, stemness and peritoneal metastasis of ovarian cancer cells. The increase in urokinase plasminogen activator receptor (uPAR) α1,3-mannosylation catalyzed by ALG3 enhanced urokinase plasminogen activator (uPA)/uPAR activation and the interaction of uPAR with a disintegrin and metalloproteinase 8 (ADAM8), which promoted ovarian cancer peritoneal metastasis via the ADAM8/Ras/ERK pathway. Furthermore, decreased ALG3 suppressed ascites formation and the peritoneal metastasis of ovarian cancer cells in mice. This study highlights ALG3 as a potential diagnostic biomarker and prospective therapeutic target for ovarian cancer.

CircPTK2 promotes cell viability, cell cycle process, and glycolysis and inhibits cell apoptosis in acute myeloid leukemia by regulating miR-582-3p/ALG3 axis.

BACKGROUND: Circular RNA (circRNA) regulates the pathogenesis of acute myeloid leukemia (AML). However, the mechanism of circRNA protein tyrosine kinase 2 (circPTK2) in AML remains unclear. METHODS: Quantitative real-time polymerase chain reaction (qRT-PCR) assay was adopted for circPTK2, miR-582-3p and alpha-1,3-mannosyltransferase (ALG3) mRNA levels. 3-(4, 5-Dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay, and 5'-ethynyl-2'-deoxyuridine (EdU) assay were conducted for cell proliferation. Flow cytometry analysis was employed for cell apoptosis and cell cycle process. The glycolysis level was estimated by specific commercial kits. Western blot assay was utilized for protein levels. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to verify the interaction between miR-582-3p and circPTK2 or ALG3. RESULTS: CircPTK2 level was enhanced in AML peripheral blood samples and cells. CircPTK2 knockdown restrained AML cell proliferation and glycolysis and promoted cell apoptosis and cell cycle arrest. Mechanically, circPTK2 functioned as the sponge for miR-582-3p to positively ALG3 expression in AML cells. Moreover, miR-582-3p inhibition ameliorated the impacts of circPTK2 knockdown on AML cell processes. MiR-582-3p overexpression regulated cell phenotypes by targeting ALG3. CONCLUSION: CircPTK2 contributed to AML cell malignant behaviors by modulation of miR-582-3p/ALG3 axis, which might provide a potential target for AML therapy.

Expression of ALG3 in Hepatocellular Carcinoma and Its Clinical Implication.

Background: Recent studies have shown that alpha-1,3-mannosyltransferase (ALG3) promoted tumorigenesis and progression in multiple cancer types. Our study planned to explore the clinical implication and potential function of ALG3 in hepatocellular carcinoma. Materials and Methods: Data from public databases were used to analyze the ALG3 expression and its impact on the clinical significance of patients with HCC. The ALG3 expression was confirmed by qRT-PCR and Western blot. Immunohistochemistry was used to confirm the ALG3 expression and explore its clinical implication in HCC. KEGG, GO, and GSEA enrichment analyses were utilized to explore the biological pathways related to ALG3 in HCC. TIMER2.0 was applied to assess the association between ALG3 and immune infiltration. CCK8, MTT, and transwell assays were used to investigate the role of ALG3 downregulation in HCC cell lines. Results: qRT-PCR, WB, and IHC proved ALG3 was highly overexpressed in HCC tissues. The Kaplan-Meier analysis verified the overexpression of ALG3 was related to poor overall survival (p < 0.001). Multivariate cox regression analysis showed that the high ALG3 expression was an independent risk prognostic factor. GSEA and TIMER2.0 predicted that ALG3 participates in cell differentiation and cycle and correlates with immune cell infiltration. Transwell assay results showed that ALG3 silencing also impaired the invasion ability of HCC cells. Conclusion: ALG3 was overexpressed and considered a potential indicator of survival in HCC, and our findings provided a novel therapeutic target for HCC.

Inhibition of ALG3 stimulates cancer cell immunogenic ferroptosis to potentiate immunotherapy.

Immune checkpoint blockade therapy has drastically improved the prognosis of certain advanced-stage cancers. However, low response rates and immune-related adverse events remain important limitations. Here, we report that inhibiting ALG3, an a-1,3-mannosyltransferase involved in protein glycosylation in the endoplasmic reticulum (ER), can boost the response of tumors to immune checkpoint blockade therapy. Deleting N-linked glycosylation gene ALG3 in mouse cancer cells substantially attenuates their growth in mice in a manner depending on cytotoxic T cells. Furthermore, ALG3 inhibition or N-linked glycosylation inhibitor tunicamycin treatment synergizes with anti-PD1 therapy in suppressing tumor growth in mouse models of cancer. Mechanistically, we found that inhibiting ALG3 induced deficiencies of post-translational N-linked glycosylation modification and led to excessive lipid accumulation through sterol-regulated element-binding protein (SREBP1)-dependent lipogenesis in cancer cells. N-linked glycosylation deficiency-mediated lipid hyperperoxidation induced immunogenic ferroptosis of cancer cells and promoted a pro-inflammatory microenvironment, which boosted anti-tumor immune responses. In human subjects with cancer, elevated levels of ALG3 expression in tumor tissues are associated with poor patient survival. Taken together, we reveal an unappreciated role of ALG3 in regulating tumor immunogenicity and propose a potential therapeutic strategy for enhancing cancer immunotherapy.

ALG3 Is a Potential Biomarker for the Prognosis of Bladder Cancer.

OBJECTIVE: Previous research showed that ALG3 was associated with several cancers, but the function of ALG3 in bladder cancer (BC) was yet unknown. The purpose of this study was to investigate the relative expression of ALG3 in BC tissues and corresponding normal tissues and the relationship between the relative expression of ALG3 and clinical outcome in bladder cancer patients. METHODS: In this study, the expression of ALG3 in bladder cancer was detected by immunochemistry. In order to determine the cell proliferation and migration ability more accurately, we performed colony forming assay, MTT assay and wound healing migration assay. The role of ALG3 on tumor growth and metastasis was explored by animal model in vivo. RESULTS: ALG3 was expressed higher in bladder cancer than that in the normal tissues (P<0.05). At the same time, we found that there was a positive correlation between ALG3 expression and the prognosis (P<0.05). Moreover, we also discovered that the expression of ALG3 was associated with clinical pathological features (P<0.05). The proliferation and migration abilities of bladder cancer cell line T24 and 5637 were inhibited by silencing ALG3. In addition, the growth of bladder cancer cell line T24 cells were inhibited by silencing ALG3 in vivo. CONCLUSION: Silencing ALG3 plays a critical role in bladder cancer development and growth. It inhibits bladder cancer cells growth in vitro and in vivo.

Production of Human Acid-Alpha Glucosidase With a Paucimannose Structure by Glycoengineered Arabidopsis Cell Culture.

Plant cell cultures have emerged as a promising platform for the production of biopharmaceutics due to their cost-effectiveness, safety, ability to control the cultivation, and secrete products into culture medium. However, the use of this platform is hindered by the generation of plant-specific N-glycans, the inability to produce essential N-glycans for cellular delivery of biopharmaceutics, and low productivity. In this study, an alternative acid-alpha glucosidase (GAA) for enzyme replacement therapy of Pompe disease was produced in a glycoengineered Arabidopsis alg3 cell culture. The N-glycan composition of the GAA consisted of a predominantly paucimannosidic structure, Man3GlcNAc2 (M3), without the plant-specific N-glycans. Supplementing the culture medium with NaCl to a final concentration of 50 mM successfully increased GAA production by 3.8-fold. GAA from an NaCl-supplemented culture showed a similar N-glycan profile, indicating that the NaCl supplementation did not affect N-glycosylation. The results of this study highlight the feasibility of using a glycoengineered plant cell culture to produce recombinant proteins for which M3 or mannose receptor-mediated delivery is desired.

ALG3-CDG: a patient with novel variants and review of the genetic and ophthalmic findings.

BACKGROUND: ALG3-CDG is a rare autosomal recessive disease. It is characterized by deficiency of alpha-1,3-mannosyltransferase caused by pathogenic variants in the ALG3 gene. Patients manifest with severe neurologic, cardiac, musculoskeletal and ophthalmic phenotype in combination with dysmorphic features, and almost half of them die before or during the neonatal period. CASE PRESENTATION: A 23 months-old girl presented with severe developmental delay, epilepsy, cortical atrophy, cerebellar vermis hypoplasia and ocular impairment. Facial dysmorphism, clubfeet and multiple joint contractures were observed already at birth. Transferrin isoelectric focusing revealed a type 1 pattern. Funduscopy showed hypopigmentation and optic disc pallor. Profound retinal ganglion cell loss and inner retinal layer thinning was documented on spectral-domain optical coherence tomography imaging. The presence of optic nerve hypoplasia was also supported by magnetic resonance imaging. A gene panel based next-generation sequencing and subsequent Sanger sequencing identified compound heterozygosity for two novel variants c.116del p.(Pro39Argfs*40) and c.1060 C > T p.(Arg354Cys) in ALG3. CONCLUSIONS: Our study expands the spectrum of pathogenic variants identified in ALG3. Thirty-three variants in 43 subjects with ALG3-CDG have been reported. Literature review shows that visual impairment in ALG3-CDG is most commonly linked to optic nerve hypoplasia.

ALG3 contributes to stemness and radioresistance through regulating glycosylation of TGF-ß receptor II in breast cancer.

BACKGROUND: Radiotherapy is a conventional and effective local treatment for breast cancer. However, residual or recurrent tumors appears frequently because of radioresistance. Novel predictive marker and the potential therapeutic targets of breast cancer radioresistance needs to be investigated. METHODS: In this study, we screened all 10 asparagine-linked glycosylation (ALG) members in breast cancer patients' samples by RT-PCR. Cell viability after irradiation (IR) was determined by CCK-8 assay and flow cytometry. The radiosensitivity of cell lines with different ALG3 expression was determined with the colony formation assay by fitting the multi-target single hit model to the surviving fractions. Cancer stem-like traits were assessed by RT-PCR, Western blot, and flow cytometry. The mechanisms of ALG3 influencing radiosensitivity was detected by Western blot and immunoprecipitation. And the effect of ALG3 on tumor growth after IR was verified in an orthotopic xenograft tumor models. The association of ALG3 with prognosis of breast cancer patients was confirmed by immunohistochemistry. RESULTS: ALG3 was the most significantly overexpressing gene among ALG family in radioresistant breast cancer tissue. Overexpression of ALG3 predicted poor clinicopathological characteristics and overall survival (OS), and early local recurrence-free survival (LRFS) in breast cancer patients. Upregulating ALG3 enhanced radioresistance and cancer stemness in vitro and in vivo. Conversely, silencing ALG3 increased the radiosensitivity and repressed cancer stemness in vitro, and more importantly inhibition of ALG3 effectively increased the radiosensitivity of breast cancer cells in vivo. Mechanistically, our results further revealed ALG3 promoted radioresistance and cancer stemness by inducing glycosylation of TGF-ß receptor II (TGFBR2). Importantly, both attenuation of glycosylation using tunicamycin and inhibition of TGFBR2 using LY2109761 differentially abrogated the stimulatory effect of ALG3 overexpression on cancer stemness and radioresistance. Finally, our findings showed that radiation played an important role in preventing early recurrence in breast cancer patients with low ALG3 levels, but it had limited efficacy in ALG3-overexpressing breast cancer patients. CONCLUSION: Our results suggest that ALG3 may serve as a potential radiosensitive marker, and an effective target to decrease radioresistance by regulating glycosylation of TGFBR2 in breast cancer. For patients with low ALG3 levels, radiation remains an effective mainstay therapy to prevent early recurrence in breast cancer.

Analysis of N-glycan profile of Arabidopsis alg3 cell culture.

N-Glycosylation is essential for protein stability, activity and characteristics, and is often needed to deliver pharmaceutical glycoproteins to target cells. A paucimannosidic structure, Man3GlcNAc2 (M3), has been reported to enable cellular uptake of glycoproteins through the mannose receptor (MR) in humans, and such uptake has been exploited for the treatment of certain diseases. However, M3 is generally produced at a very low level in plants. In this study, a cell culture was established from an Arabidopsis alg3 mutant plant lacking asparagine-linked glycosylation 3 (ALG3) enzyme activity. Arabidopsis alg3 cell culture produced glycoproteins with predominantly M3 and GlcNAc-terminal structures, while the amount of plant-specific N-glycans was very low. Pharmaceutical glycoproteins with these characteristics would be valuable for cellular delivery through the MR, and safe for human therapy.

ALG3 contributes to the malignant properties of OSCC cells by regulating CDK-Cyclin pathway.

In this study, we planned to investigate the function and potential mechanisms of Alpha-1,3-mannosyltransferase (ALG3) in oral squamous cell carcinoma (OSCC). Data from TCGA were used to analyze ALG3 expression and its effect on the prognosis of patients with OSCC. KEGG enrichment analysis was applied to explore the pathways related to ALG3. ALG3 expression was measured by qPCR and Western blot. Cell counting kit-8, colony formation, and transwell assays were implemented to detect the effects of ALG3 on malignant biological properties of OSCC cells. The expression of key proteins related to CDK-Cyclin pathway was detected by Western blot. The expression of ALG3 in OSCC samples was higher than that of the control samples, and the increase of ALG3 expression was related to unfavorable prognosis of OSCC patients. Additionally, the elevated expression of ALG3 was associated with pathological stage, lymph node metastasis, and primary lesion in OSCC patients. ALG3 depletion blocked the growth and movement of OSCC cells, while over-expression ALG3 reversed these phenomena. Moreover, exhaustion of ALG3 resulted in decreased expression of MCM7/CCNB2/CDK1/PCNA, while these phenomena were inversed after ALG3 up-regulation. The enhancement of ALG3 expression promoted the aggressive biological behaviors of OSCC cells probably by promoting CDK-Cyclin pathway.

Successful treatment of intractable epilepsy with ketogenic diet therapy in twins with ALG3-CDG.

BACKGROUND: Congenital disorders of glycosylation (CDG) is a heterogeneous group of congenital metabolic diseases with multisystem clinical involvement. ALG3-CDG is a very rare subtype with only 24 cases reported so far. CASE: Here, we report two siblings with dysmorphic features, growth retardation, microcephaly, intractable epilepsy, and hemangioma in the frontal, occipital and lumbosacral regions. RESULTS: We studied two siblings by whole exome sequencing. A pathogenic variant in ALG3 (NM_005787.6: c.165C > T; p.Gly55=) that had been previously associated with congenital glycolysis defect type 1d was identified. Their intractable seizures were controlled by ketogenic diet. CONCLUSION: Although prominent findings of growth retardation and microcephaly seen in our patients have been extensively reported before, presence of hemangioma is a novel finding that may be used as an indication for ALG3-CDG diagnosis. Our patients are the first reported cases whose intractable seizures were controlled with ketogenic diet. This report adds ketogenic diet as an option for treatment of intractable epilepsy in ALG3-CDG.

Novel variants and clinical symptoms in four new ALG3-CDG patients, review of the literature, and identification of AAGRP-ALG3 as a novel ALG3 variant with alanine and glycine-rich N-terminus.

ALG3-CDG is one of the very rare types of congenital disorder of glycosylation (CDG) caused by variants in the ER-mannosyltransferase ALG3. Here, we summarize the clinical, biochemical, and genetic data of four new ALG3-CDG patients, who were identified by a type I pattern of serum transferrin and the accumulation of Man5 GlcNAc2 -PP-dolichol in LLO analysis. Additional clinical symptoms observed in our patients comprise sensorineural hearing loss, right-descending aorta, obstructive cardiomyopathy, macroglossia, and muscular hypertonia. We add four new biochemically confirmed variants to the list of ALG3-CDG inducing variants: c.350G>C (p.R117P), c.1263G>A (p.W421*), c.1037A>G (p.N346S), and the intron variant c.296+4A>G. Furthermore, in Patient 1 an additional open-reading frame of 141 bp (AAGRP) in the coding region of ALG3 was identified. Additionally, we show that control cells synthesize, to a minor degree, a hybrid protein composed of the polypeptide AAGRP and ALG3 (AAGRP-ALG3), while in Patient 1 expression of this hybrid protein is significantly increased due to the homozygous variant c.160_196del (g.165C>T). By reviewing the literature and combining our findings with previously published data, we further expand the knowledge of this rare glycosylation defect.

Combined expression and prognostic significance of PPFIA1 and ALG3 in head and neck squamous cell carcinoma.

PPFIA family members and ALG3 play important roles in tumorigenesis and tumor progression. However, the exact roles of distinct PPFIA family members and ALG3 in head and neck squamous cell carcinoma (HNSCC) remain unclear. We studied the mRNA expressions of PPFIA family members and ALG3 in a variety of tumor types compared with the normal controls using the Oncomine database along with meta-analyses of their expressions in HNSCC cancer cell line. The mRNA expressions of PPFIA family members and ALG3 in laryngeal squamous cell carcinoma cell line and normal laryngeal cell line were detected by quantitative real-time polymerase chain reaction. Based on the cBioportal database, we further studied mRNA expression alterations and co-occurrence relationships of the PPFIA family members and ALG3 in HNSCC. The relationship between PPFIA1 and ALG3 mRNA expression alterations and prognoses in patients with HNSCC was explored. We found that PPFIA1 and ALG3 were distinctively overexpressed at the mRNA level in HNSCC tissues compared with normal tissues, they had a significant co-occurrence relationship, their mRNA expressions were significantly higher than other PPFIA family members in laryngeal squamous cell carcinoma cell line, and their mRNA expressions were also significantly higher in laryngeal carcinoma cell line than in normal laryngeal cell line. Patients without both PPFIA1 and ALG3 mRNA expression alterations had better overall survival and disease/progression-free survival compared with patients with both PPFIA1 and ALG3 alterations. Based on these findings, PPFIA1 and ALG3 may play roles in oncogene expression in HNSCC. Their combined overexpression is significantly associated with poor survival outcomes. The relationship between them and the mechanism of action in head and neck cancers deserve further investigation.

Electroclinical Features of Early-Onset Epileptic Encephalopathies in Congenital Disorders of Glycosylation (CDGs).

Congenital disorders of glycosylation (CDG) are a constantly growing group of genetic defects of glycoprotein and glycolipid glycan synthesis. CDGs are usually multisystem diseases, and in the majority of patients, there is an important neurological involvement comprising psychomotor disability, hypotonia, ataxia, seizures, stroke-like episodes, and peripheral neuropathy. To assess the incidence, among early-onset epileptic encephalopathies (EOEE), of patients with identified congenital disorders of glycosylation (CDG), we made a review of clinical, electrophysiological, and neuroimaging findings of 27 CDG patients focusing on seizure onset, semiology and frequency, response to antiepileptic drugs (AED), and early epileptic manifestations. Epilepsy was uncommon in PMM2-CDG (11%), while it was a main concern in other rare forms. We describe a series of patients with EOEE and genetically confirmed CDG (ALG3-CDG, ALG6-CDG, DPM2-CDG, ALG1-CDG). Epileptic seizures at onset included myoclonic and clonic fits and focal seizures. With time, patients developed recurrent and intractable seizures principally tonic-clonic seizures, infantile spasms, and myoclonic seizures. Electrophysiological correlates included focal and multifocal epileptic discharges, slowed background rhythm, and generalized epileptic activity including burst suppression pattern and status epilepticus. We propose a diagnostic flowchart for the early diagnosis of CDG in patients presenting with EOEE and suggest to perform serum transferrin IEF (or capillary zone electrophoresis) as a first-line screening in early-onset epilepsy.

ALG3-CDG: Report of two siblings with antenatal features carrying homozygous p.Gly96Arg mutation.

Congenital disorders of glycosylation (CDG) are a group of inborn errors of metabolism presenting with heterogeneous multisystemic clinical manifestations. To date, more than 60 different types of CDG have been reported. ALG3-CDG is very rare, with only nine patients described so far. We report two affected siblings presenting prenatally with skeletal abnormalities associated with dysmorphic features, cerebellar vermis hypoplasia, corpus callosum agenesis, hepatic fibrosis and poor prognosis. This is the first detailed report of an affected fetus including clinical, radiographic and pathological findings. The patients showed some clinical features previously unreported in ALG3-CDG, such as bone dysplasia, cataract, corneal opacities, and pons hypoplasia. Both patients were homozygous for the previously unreported p.Gly96Arg mutation of the ALG3 gene. One patient showed chondrodysplasia punctata (CDP), which has not been previously reported in CDG. An exhaustive genetic and metabolic assessment, performed in order to rule out other possible causes of CDP, showed abnormally raised levels of anti-nuclear antibodies in the mother who, nevertheless, did not show any clinical sign of autoimmune disease during a 7 years follow-up. We speculate that the observed CDP may be explained by the maternal anti-nuclear antibodies; alternatively, a possible link to the underlying metabolic disorder cannot be ruled out. In conclusion, we report the clinical, pathological, biochemical and molecular characterization of two further patients affected by ALG3-CDG, expanding the phenotypic spectrum of this very rare disease.