Glutamine metabolic microenvironment drives M2 macrophage polarization to mediate trastuzumab resistance in HER2‐positive gastric cancer

Abstract

Background Trastuzumab is a first‐line targeted therapy for human epidermal growth factor receptor‐2 (HER2)‐positive gastric cancer. However, the inevitable occurrence of acquired trastuzumab resistance limits the drug benefit, and there is currently no effective reversal measure. Existing researches on the mechanism of trastuzumab resistance mainly focused on tumor cells themselves, while the understanding of the mechanisms of environment‐mediated drug resistance is relatively lacking. This study aimed to further explore the mechanisms of trastuzumab resistance to identify strategies to promote survival in these patients. Methods Trastuzumab‐sensitive and trastuzumab‐resistant HER2‐positive tumor tissues and cells were collected for transcriptome sequencing. Bioinformatics were used to analyze cell subtypes, metabolic pathways, and molecular signaling pathways. Changes in microenvironmental indicators (such as macrophage, angiogenesis, and metabolism) were verified by immunofluorescence (IF) and immunohistochemical (IHC) analyses. Finally, a multi‐scale agent‐based model (ABM) was constructed. The effects of combination treatment were further validated in nude mice to verify these effects predicted by the ABM. Results Based on transcriptome sequencing, molecular biology, and in vivo experiments, we found that the level of glutamine metabolism in trastuzumab‐resistant HER2‐positive cells was increased, and glutaminase 1 (GLS1) was significantly overexpressed. Meanwhile, tumor‐derived GLS1 microvesicles drove M2 macrophage polarization. Furthermore, angiogenesis promoted trastuzumab resistance. IHC showed high glutamine metabolism, M2 macrophage polarization, and angiogenesis in trastuzumab‐resistant HER2‐positive tumor tissues from patients and nude mice. Mechanistically, the cell division cycle 42 (CDC42) promoted GLS1 expression in tumor cells by activating nuclear factor kappa‐B (NF‐κB) p65 and drove GLS1 microvesicle secretion through IQ motif‐containing GTPase‐activating protein 1 (IQGAP1). Based on the ABM and in vivo experiments, we confirmed that the combination of anti‐glutamine metabolism, anti‐angiogenesis, and pro‐M1 polarization therapy had the best effect in reversing trastuzumab resistance in HER2‐positive gastric cancer. Conclusions This study revealed that tumor cells secrete GLS1 microvesicles via CDC42 to promote glutamine metabolism, M2 macrophage polarization, and pro‐angiogenic function of macrophages, leading to acquired trastuzumab resistance in HER2‐positive gastric cancer. A combination of anti‐glutamine metabolism, anti‐angiogenesis, and pro‐M1 polarization therapy may provide a new insight into reversing trastuzumab resistance.

Exploring the immune escape mechanisms in gastric cancer patients based on the deep AI algorithms and single‐cell sequencing analysis

“… 35 M2 macrophages can also produce anti‐inflammatory and apoptosis‐inhibiting factors, suppressing the activity of immune cells and weakening the presentation of tumour antigens and the immune system's killing effect on tumours. 36 M2 macrophages can secrete matrix metalloproteinases and detachment‐related factors that promote tumour cell invasion and metastasis by disrupting the basement membrane, as well as enhancing tumour cell invasion and metastatic abilities through interactions with gastric adenocarcinoma cells, releasing cytokines and chemokines. 37 , 38 Anti‐inflammatory cytokines and immune‐suppressive molecules produced during the polarization of M2 macrophages, such as anti‐inflammatory cytokine IL‐10 and anti‐inflammatory cytokine TGF‐β, suppress the activity of immune cells such as T cells and natural killer cells, weakening their attack against tumour cells and promoting immune escape of the tumour.…”

Tumour‐associated macrophages in gastric cancer: From function and mechanism to application

“…found that patients with high infiltration of macrophages (CD68) were often related to poor response to neoadjuvant chemotherapy in a 103 sample cohort 41 . Meanwhile, high infiltration of M2 TAMs (CD206) was usually forecasted as resistant to trastuzumab therapy in patients with HER2‐positive GC 71 . Sun et al.…”

“…As a key communication medium in the TME, 62 EVs exert a critical function in inducing the polarisation of TAMs 63 . Accumulative research has reported that EVs containing microRNAs, circular RNAs, long non‐coding RNAs (lncRNAs) or proteins derived from GC cells regulated the polarisation of TAMs after the internalisation by macrophages 52,64–71 . Notably, natural compounds extracted from plants, such as flavokawain B, sophoridine, diosmetin, elian granules and betulinic acid, were found to enhance the polarisation of M1 TAMs 72–76 .…”

“…Also, M2 TAMs activated the PI3K/AKT/mTOR pathway to confer resistance to 5‐fluorouracil (5‐FU) by improving the level of CXCL5 in GC cells 41 . Several studies observed that decreased M1 TAMs or increased M1 TAMs conferred trastuzumab resistance in HER2‐positive GC cells 16,71 . Additionally, the transfer of EVs containing lncRNA CRNDE derived from M2 TAMs to GC cells conferred cisplatin resistance by promoting neural precursor cell expressed developmentally downregulated protein 4‐1 (NEDD4‐1)‐mediated ubiquitination and degradation of phosphatase and tensin homolog (PTEN) 36 .…”

The role of lncRNA HCG18 in human diseases

“…Xu et al 40 reported that HCG18 can promote cetuximab resistance in CRC cells through the miR‐20b‐5p/PD‐L1 axis. In the multidrug resistance of cancer, upregulation of FOXO1 expression and M2 macrophage polarization can enhance the drug resistance of tumor cells 82–85 . Overexpression of miR‐365a‐3p inhibits multidrug resistance in CRC cells 54 .…”