Enhanced ASGR2 by microplastic exposure leads to resistance to therapy in gastric cancer

Abstract

Background: Microplastics (MPs) are a new global environmental threat. Previously, we showed the biodistribution of MPs using [ 64 Cu] polystyrene (PS) and PET in mice. Here, we aimed to identify whether PS exposure has malignant effects on the stomach and induces resistance to therapy. Methods: BALB/c nude mice were fed 1.72 × 10 4 particles/mL of MP. We investigated PS accumulation in the stomach using radioisotope-labeled and fluorescent-conjugated PS. Further, we evaluated whether PS exposure induced cancer stemness and multidrug resistance, and whether it affected tumor development, tumor growth, and survival rate in vivo using a 4-week PS-exposed NCI-N87 mouse model. Using RNA-Seq analysis, we analyzed whether PS exposure induced gene expression changes in gastric tissues of mice. Results: PET imaging results showed that a single dose of [ 64 Cu]-PS remained for 24 h in the mice stomach. The 4-week daily repetitive dose of fluorescent conjugated PS was deposited in the gastric tissues of mice. When PS was exposed, a 2.9-fold increase in migration rate was observed for NCI-N87 cells. Immunocytochemistry results showed decreased E-cadherin and increased N-cadherin expression, and flow cytometry, qPCR, and western blot analysis indicated a 1.9-fold increase in N-cadherin expression after PS exposure . Further, PS-induced multidrug resistance to bortezomib, paclitaxel, gefitinib, lapatinib, and trastuzumab was observed in the NCI-N87 mouse model due to upregulated CD44 expression. RNA-seq results identified increased asialoglycoprotein receptor 2 ( ASGR2 ) expression after PS exposure, and ASGR2 knockdown decreased cell proliferation, migration, invasion, and drug resistance. Conclusion: We demonstrated that ASGR2 enhanced cancer hallmarks on PS exposure and induced resistance to chemo- and monoclonal antibody-therapy. Our preclinical findings may provide an incentive for further epidemiological studies on the role of MP exposure and its association with gastric cancer.

Insights into the potential carcinogenicity of micro- and nano-plastics

“…Two of the in vivo discussed studies reported that MNPLs were administered in drinking water or food although no specification on the consumption per animal was given [41,42]. Similarly, Kim and colleagues reported the concentration of particles administered per mouse without mentioning the volume administered [35]. A comprehensive and detailed description of these procedures is fundamental for comparing the results between studies.…”

“…Moreover, and as indicators of an advanced tumoral phenotype, there was a significantly elevated number of colonies able to grow in soft-agar and increased cell migration capacity, as well as an aggressive tumoral phenotype, namely, increased invasion capacity, changes in pluripotency markers (upregulated Klf4, Nanog, Notch2, and Oct3/4 and downregulated Sox2) and formation of tumorspheres due to the treatment of the cells with PSNPLs for 24 weeks. On the other hand, Kim and colleagues studied carcinogenicity-related endpoints in AGS, MKN1, MKN45, NCI-N87, and KATO III human gastric cancer cell lines after the exposure to 8.61 × 10 5 particles/mL of PSMPLs (9.5-11.5 µm) for 4 weeks [35]. As a result of the exposure, all cell lines increased their proliferation and migration rates, and most of them except NCI-N87 cells underwent invasion induction.…”

“…Only one study focusing on in vivo tumorigenesis capacity of PSMPLs (9.5-11.5 µm) was found [35]. Mice xenografts (BALB/c nude mice injected with NCI-N87 cells previously exposed or not to 8.61 ×10 5 PS particles/mL for 4 weeks) were used to demonstrate an induction in tumor growth in the PSMPLs-exposed NCI-N87 mouse model compared to the control.…”

Microplastic sources, formation, toxicity and remediation: a review

“…Although several research works have explored the effects of plastic on humans, its impact on the stomach is still unclear (Campanale et al 2020 ). Recently, Kim et al ( 2022 ) demonstrated that long-term exposure to microplastics can increase the risk of stomach cancer. The presence of microplastics has caused the enhanced expression level of asialoglycoprotein receptor 2 (ASGR2).…”

“…The elevated level of ASGR2 indicates the presence of typical cancer hallmarks such as CD44, N-cadherin, programmed death ligand 1 and proliferation. In addition, the excess exposure to microplastics caused a decrease in survival rate and an increase in the growth of tumours (Kim et al 2022). Wang et al (2020c) reported that the different size of microplastics affects their toxicity in humans.…”