Chaperonin-containing tailless complex polypeptide 1 subunit 6A negatively regulates autophagy and protects colorectal cancer cells from cisplatin-induced cytotoxicity

Abstract

BACKGROUND

As a member of the chaperonin-containing tailless complex polypeptide 1 (TCP1) complex, which plays a pivotal role in ensuring the accurate folding of numerous proteins, chaperonin-containing TCP1 subunit 6A (CCT6A) participates in various physiological and pathological processes. However, its effects on cell death and cancer therapy and the underlying mechanisms need further exploration in colorectal cancer (CRC) cells.

AIM

To explore the effects of CCT6A on cell death and cancer therapy and the underlying mechanisms in CRC.

METHODS

Cell proliferation was evaluated using the MTS assay, EdU staining, and colony growth assays. The expression of CCT6A was monitored by immunoblotting and quantitative PCR. CCT6A was knocked out by CRISPR-Cas9, and overexpressed by transfecting plasmids. Autophagy was examined by immunoblotting and the mCherry-GFP-LC3 assay. To monitor apoptosis and necroptosis, immunoblotting, co-immunoprecipitation, and flow cytometry were employed.

RESULTS

Cisplatin (DDP) exerted cytotoxic effects on CRC cells while simultaneously downregulating the expression of CCT6A. Depletion of CCT6A amplified the cytotoxic effects of DDP, whereas overexpression of CCT6A attenuated these adverse effects. CCT6A suppressed autophagy, apoptosis, and necroptosis under both basal and DDP-treated conditions. Autophagy inhibitors significantly enhanced the cytotoxic effects of DDP, whereas a necroptosis inhibitor partially reversed the cell viability loss induced by DDP. Furthermore, inhibiting autophagy enhanced both apoptosis and necroptosis induced by DDP.

CONCLUSION

CCT6A negatively modulates autophagy, apoptosis, and necroptosis, and CCT6A confers resistance to DDP therapy in CRC, suggesting its potential as a therapeutic target.

Keywords: Chaperonin-containing tailless complex polypeptide 1 subunit 6a; Cisplatin; Autophagy; Colorectal cancer; Necroptosis

Core Tip: This study evaluated the role of chaperonin-containing tailless complex polypeptide 1 subunit 6A (CCT6A) in colorectal cancer (CRC) therapy. CCT6A expression was downregulated by cisplatin (DDP) in CRC cells, enhancing its cytotoxicity. Depletion of CCT6A potentiated DDP's effects by promoting autophagy, apoptosis, and necroptosis, whereas its overexpression provided resistance. Immunoblotting and autophagy confirmed CCT6A's negative regulatory role in autophagy. Markers of apoptosis and necroptosis were upregulated in CCT6A-depleted cells, indicating increased cell death. Autophagy inhibition exacerbated cell death, compromising viability and proliferation. Thus, CCT6A is a potential therapeutic target in CRC, modulating key cellular processes and enhancing DDP efficacy.