Keratinocyte-associated protein 2 alleviates ricin-induced apoptosis by regulating autophagy

To explore the effect of knockdown of keratinocyte associated protein 2 (KRTCAP2) on ricin-induced apoptosis and the related mechanism.

Small interfering RNA (siRNA) transfection was used to establish siNC and siKRTCAP2 cell lines in the cervical cancer cell line HeLa. Real-time quantitative polymerase chain reaction (RT-qPCR) was performed to detect the mRNA expression level of KRTCAP2. Western blot assay was used to evaluate the levels of autophagy and apoptosis. The monodansylcadaverine (MDC) staining kit for cellular autophagy was applied to detect the formation of autophagosomes in siRNA-transfected cells. Cell Counting Kit-8 (CCK-8) assay and colony formation assay were conducted to determine cell viability. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining was used to assess cell apoptosis.

Knockdown of KRTCAP2 significantly enhanced autophagy. Compared with the siNC group, the mRNA expression level of KRTCAP2 was markedly decreased in the siKRTCAP2 group, in which autophagy was significantly elevated, along with significant upregulation of fluorescent signals of autophagosomes. Ricin induced the death of wild-type HeLa cells in a concentration-dependent manner and inhibited cellular autophagy. Knockdown of KRTCAP2 improved cellular resistance to ricin by enhancing autophagy. Compared with the siNC group, autophagy kept increasing while cell viability was enhanced under ricin induction in the siKRTCAP2 group. Chloroquine (CQ), an autophagy inhibitor, partially blocked the resistance of siKRTCAP2-transfected cellsto ricin, accompanied by reduced autophagy and cell viability. In addition, knockdown of KRTCAP2 mitigated ricin-induced cell apoptosis.

Knockdown of KRTCAP2 can enhance autophagy while ameliorating cell apoptosis induced by ricin, thereby exerting a protective effect on cells.