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

Abstract

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-β 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.

A Novel Prognostic Signature Based on Metabolism-Related Genes to Predict Survival and Guide Personalized Treatment for Head and Neck Squamous Carcinoma

“…Increased expression of ALG3 was observed in HNSCC cell line ( 26 ). Moreover, ALG3 as a class of glycosyltransferases promotes the proliferation and radiosensitivity of cancer cells and is related with poor prognosis and lymph node metastasis ( 27 , 28 ). CHPF2 acts as an oncogene that is up-regulated in cancers to exert its positive role in cell proliferation and metastasis, including breast cancer, hepatocellular carcinoma, lung adenocarcinoma, etc.…”

Breast Cancer with Bone Metastasis: Molecular Insights and Clinical Management

“…Finally, TGFβ, CXCR4, and αvβ3 integrin are key mediators of breast cancer metastasis to bone (Table 2) [93][94][95][96]. Antagonists of these proteins are under investigation in preclinical models of metastatic breast cancer, showing accumulating positive data [97][98][99][100][101][102][103][104][105][106][107][108]. Assessment of their safety and efficacy in phase I clinical trials is expected.…”

Clinically Translatable Approaches of Inhibiting TGF-β to Target Cancer Stem Cells in TNBC

“…A study by Sun et al further looked into the association between TGF-β, CSC enrichment, and radioresistance. Sun et al demonstrated that following initial radiotherapy, breast cancer patients who demonstrated radioresistance and recurrence within 5 years of their initial therapy were found to have increased expression of ALG3 (Alpha-1,3-Mannosyltransferase) [73]. These findings were correlated with breast cancer cell lines where basal-like and HER-2+ breast cancer lines demonstrated increased levels of radioresistance and ALG3 expression.…”

“…This co-immunoprecipitation was not observed in ALG3 knockout cell lines. A TGFβR2 inhibitor (LY2109761) was then used to inhibit ALG2 overexpressing breast cancer cell lines which induced apoptosis post-radiotherapy and diminished tumorsphere formation as well as CD44+/CD24-CSCs [73].…”