DDEFL1 correlated with Rho GTPases activity in breast cancer

S-Ketamine Exerts Antidepressant Effects by Regulating Rac1 GTPase Mediated Synaptic Plasticity in the Hippocampus of Stressed Rats

Clinical studies have found that ketamine has a rapid and lasting antidepressant effect, especially in the case of patients with major depressive disorder (MDD). The molecular mechanisms, however, remain unclear. In this study, we observe the effects of S-Ketamine on the expression of Rac1, neuronal morphology, and synaptic transmission function in the hippocampus of stressed rats. Chronic unpredictable mild stress (CUMS) was used to construct stressed rats. The rats were given a different regimen of ketamine (20 mg/kg, i.p.) and Rac1 inhibitor NSC23766 (50 µg, ICV) treatment. The depression-like behavior of rats was evaluated by sucrose preference test and open-field test. The protein expression of Rac1, GluA1, synapsin1, and PSD95 in the hippocampus was detected by Western blot. Pull-down analysis was used to examine the activity of Rac1. Golgi staining and electrophysiological study were used to observe the neuronal morphology and long-term potentiation (LTP). Our results showed that ketamine can up-regulate the expression and activity of Rac1; increase the spine density and the expression of synaptic-related proteins such as GluA1, Synapsin1, and PSD95 in the hippocampus of stressed rats; reduce the CUMS-induced LTP impairments; and consequently improve depression-like behavior. However, Rac1 inhibitor NSC23766 could have effectively reversed ketamine-mediated changes in the hippocampus of rats and counteracted its antidepressant effects. The specific mechanism of S-Ketamine's antidepressant effect may be related to the up-regulation of the expression and activity of Rac1 in the hippocampus of stressed rats, thus enhancing synaptic plasticity.

Arl13b Regulates Breast Cancer Cell Migration and Invasion by Controlling Integrin-Mediated Signaling

Breast cancer is the first cause of cancer-related mortality among women worldwide, according to the most recent estimates. This mortality is mainly caused by the tumors' ability to form metastases. Cancer cell migration and invasion are essential for metastasis and rely on the interplay between actin cytoskeleton remodeling and cell adhesion. Therefore, understanding the mechanisms by which cancer cell invasion is controlled may provide new strategies to impair cancer progression. We investigated the role of the ADP-ribosylation factor (Arf)-like (Arl) protein Arl13b in breast cancer cell migration and invasion in vitro, using breast cancer cell lines and in vivo, using mouse orthotopic models. We show that Arl13b silencing inhibits breast cancer cell migration and invasion in vitro, as well as cancer progression in vivo. We also observed that Arl13b is upregulated in breast cancer cell lines and patient tissue samples. Moreover, we found that Arl13b localizes to focal adhesions (FAs) and interacts with β3-integrin. Upon Arl13b silencing, β3-integrin cell surface levels and FA size are increased and integrin-mediated signaling is inhibited. Therefore, we uncover a role for Arl13b in breast cancer cell migration and invasion and provide a new mechanism for how ARL13B can function as an oncogene, through the modulation of integrin-mediated signaling.

RAP80 expression in breast cancer and its relationship with apoptosis in breast cancer cells

Background

RAP80 is a member of BRCA1-A complex, which plays an important role in regulating the cell cycle checkpoint and DNA damage repair in the nucleus.

Method

We investigated RAP80 expression in breast cancer and its paired normal breast tissues to further analyze its role in the biological behavior of breast cancer cells.

Results

RAP80 expression in breast cancer (62.3%, 101/162) was significantly lower than that in adjacent normal breast tissues (P<0.05). RAP80 expression was related to tumor size, lymph node metastasis, TNM stage, and molecular subtype (P<0.05). RAP80 mRNA expression was significantly lower in triple-negative breast cancer than other types. The mRNA and protein of RAP80 were obvious in MCF-7 and very weak in ZR-75 or MDA-MB-231, so we picked MCF-7 to be transfected with RAP80 siRNA. The survival rate of both cells decreased in a dose-dependent manner and the IC50 value for cisplatin in MCF-7 RAP80 siRNA cells was 0.83 µg/mL, and 1.69 µg/mL in wild-type MCF-7 according to MTT. RAP80 siRNA transfection upregulated the apoptosis and downregulated invasive or migrating ability of MCF-7. RAP80 siRNA also upregulated the protein expression of Caspase-3, cleaved Caspase-3, Apaf-1, Cytochrome C, Bax, and Fas, and downregulated the protein expression of Bcl-2.

Conclusion

RAP80 expression was related to ER or PR activity. Inhibition of RAP80 expression can induce apoptosis in breast cancer cells and improve chemosensitivity to cisplatin. Tumor cells can activate protective responses to inhibit cell cycle progression, which may be related to RAP80, and repair cisplatin-induced DNA damage. RAP80 is related to BRCA1's effect, which can be used as an interesting target for pharmacological modulation that can increase the efficiency of cisplatin chemotherapy.