CLDN6 inhibits breast cancer metastasis through WIP-dependent actin cytoskeleton-mediated autophagy

Abstract

Background As a breast cancer suppressor gene, CLDN6 overexpression was found to inhibit breast cancer metastasis in our previous studies, but the specific mechanism remains unclear. This study aimed to clarify the role and mechanism of CLDN6 in inhibiting breast cancer metastasis. Methods Western blot, immunofluorescence and transmission electron microscopy were performed to detect autophagy. Wound healing, transwell assays and lung metastasis mouse models were used to examine breast cancer metastasis. Phalloidin staining and immunofluorescent staining were used to observe actin cytoskeleton. mRNA seq, RT-PCR, western blot, chromatin immunoprecipitation, dual luciferase reporter assay, co-immunoprecipitation and immunofluorescence were performed to define the molecular mechanism. The expression levels and clinical implication of CLDN6, WIP and LC3 in breast cancer tissues were evaluated using immunohistochemistry. Results We demonstrated that CLDN6 inhibited breast cancer metastasis through autophagy in vitro and vivo. We unraveled a novel mechanism that CLDN6 regulated autophagy via WIP-dependent actin cytoskeleton assembly. Through its PDZ-binding motif, overexpressed CLDN6 interacted with JNK and upregulated JNK/c-Jun pathway. C-Jun promoted WIP expression at the transcriptional level. Notably, we observed c-Jun transcriptionally upregulated CLDN6 expression, and there was a positive feedback loop between CLDN6 and JNK/c-Jun. Finally, we found that CLDN6, WIP and LC3 expression correlated with each other, and WIP expression was significantly associated with lymph node metastasis of breast cancer patients. Conclusions The data provide a new insight into the inhibitory effects of CLDN6-mediated autophagy on breast cancer metastasis, and revealed the new mechanism of CLDN6 regulating autophagy through WIP-dependent actin cytoskeleton. Our findings enrich the theoretical basis for CLDN6 as a potential biomarker for breast cancer diagnosis and therapy.

FAM171B stabilizes vimentin and enhances CCL2-mediated TAM infiltration to promote bladder cancer progression

“…4 K) (Pearson correlation coefficient r = 0.795; Manders’ co-location coefficient M1 = 0.997 and M2 = 0.906). The colocalization criteria for two proteins were defined as follows: Pearson correlation coefficient r > 0.5 and Manders’ co-location coefficient M1 > 0.5, M2 > 0.5 [ 21 ]. Moreover, we validated the interactions between FAM171B and vimentin/HNRNPU in MB49 bladder cancer cells from mice.…”

Claudins in Cancer: A Current and Future Therapeutic Target

“…Moreover, CLDN6 was found to have an inhibitory function in breast cancer metastasis by upregulating WIP expression (WIP regulates the actin cytoskeleton autophagy pathways) during in vivo and vitro studies. This finding could explain why low levels of CLDN6 expression were found in metastatic breast cancer [101]. In colon cancer, CLDN6 activates the TYK2/STAT3 pathway, which might suppress the migration and invasion abilities of colon cancer cells [104].…”

NPFs-mediated actin cytoskeleton: a new viewpoint on autophagy regulation

“…WIP colocalizes with LC3 and p-Arp3; breast cancer cells treated with CK666 exhibit reduced autophagic flux. Besides, WIP knockdown results in reduced LC3II expression and the number of autophagosomes, and makes the actin polymerizer Jaslakinolide lose its regulatory effect on autophagy, which indicates that actin cytoskeleton dependent on WIP to regulate autophagy [ 105 ]. WIP is not a member of NPFs in the traditional definition, but it affects actin assembly by regulating multiple NPFs (WASP, N-WASP, and cortactin) [ 104 ].…”

“…However, Hasegawa et al confirmed that cortactin-mediated F-actin regulates autophagy without considering the influence of stimuli [ 101 ]. In our previous research, we found that WIP-mediated F-actin regulates autophagy without stimuli [ 105 ]. These studies indicated that NPFs can also regulate autophagy independently of stimuli.…”