ATG 4B Serves a Crucial Role in RCE-4-Induced Inhibition of the Bcl-2-Beclin 1 Complex in Cervical Cancer Ca Ski Cells.

Fang-Fang You,Xue-Qing Zhang,Fan Cheng,Kun Zou,Jian-Feng Chen,Jing Zhang

doi:10.3390/ijms222212302

Fang-Fang You, Xue-Qing Zhang + Show 4 more

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https://doi.org/10.3390/ijms222212302

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Abstract

RCE-4, a steroidal saponin isolated from Reineckia carnea, has been studied previously and has exhibited promising anti-cervical cancer properties by inducing programmed cell death (PCD) of Ca Ski cells. Considering the cancer cells developed various pathways to evade chemotherapy-induced PCD, there is, therefore, an urgent need to further explore the potential mechanisms underlying its actions. The present study focused on targeting the Bcl-2–Beclin 1 complex, which is known as the key regulator of PCD, to deeply elucidate the molecular mechanism of RCE-4 against cervical cancer. The effects of RCE-4 on the Bcl-2–Beclin 1 complex were investigated by using the co-immunoprecipitation assay. In addition, autophagy-related genes (ATG) were also analyzed due to their special roles in PCD. The results demonstrated that RCE-4 inhibited the formation of the Bcl-2–Beclin 1 complex in Ca Ski cells via various pathways, and ATG 4B proteins involved in this process served as a key co-factor. Furthermore, based on the above, the sensitivity of RCE-4 to Ca Ski cells was significantly enhanced by inhibiting the expression of the ATG 4B by applying the ATG 4B siRNA plasmid.

Highlights

Cervical cancer is the third most common gynecological malignant tumor [1]
Ski Cells of the other competitive Beclin 1‐related complexes [23,24], and these could lead to the RCE-4 was found to induce programmed cell death (PCD) of cervical cancer Ca Ski cells in our previous studies
Bcl-2 was reduced but IP Beclin 1 was increased. These results indicated that RCE-4 promoted the expression of autophagy-related genes (ATG) 14; the increased ATG 14 molecules did not participate in the formation of the Bcl-2–Beclin 1 complex, whereas they were competitively bound to Beclin 1 and formed the Beclin 1–ATG 14–Vps34–Vps15 complex (p < 0.001)

Summary

Introduction

Cervical cancer is the third most common gynecological malignant tumor [1]. Clinically, chemotherapy remains the primary therapeutic regime, but the drug resistance and serious side effects often lead to poor treatment expectations. The tumor inhibition rate for a human cervical cancer xenograft in nude mice attained 69.1% with the extremely low toxicity to normal tissues [6]. These discoveries highlighted the tremendous value of RCE-4 for treating cervical cancer. Most current anticancer chemotherapy drugs primarily act by activating programmed cell death (PCD) pathways including apoptosis and autophagy in cancer cells [8]. Tumor cells have developed novel mechanisms for evading chemotherapy-induced PCD, this could be associated with both the autophagy and inhibition of the more common apoptosis cell death pathways [11]. Evasion of apoptosis can be part of a cellular stress response to ensure the cell’s survival

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