Role of Rho guanine nucleotide exchange factors in non-small cell lung cancer

Conventionally, Rho guanine nucleotide exchange factors (GEFs) are known activators of Rho guanosine triphosphatases (GTPases) that promote tumorigenesis. However, the role of Rho GEFs in non-small cell lung cancer (NSCLC) remains largely unknown. Through the screening of 81 Rho GEFs for their expression profiles and correlations with survival, four of them were identified with strong significance for predicting the prognosis of NSCLC patients. The four Rho GEFs, namely ABR, PREX1, DOCK2 and DOCK4, were downregulated in NSCLC tissues compared to normal tissues. The downregulation of ABR, PREX1, DOCK2 and DOCK4, which can be attributfed to promoter methylation, is correlated with poor prognosis. The underexpression of the four key Rho GEFs might be related to the upregulation of MYC signaling and DNA repair pathways, leading to carcinogenesis and poor prognosis. Moreover, overexpression of ABR was shown to have a tumor-suppressive effect in PC9 and H1703 cells. In conclusion, the data reveal the unprecedented role of ABR as tumor suppressor in NSCLC. The previously unnoticed functions of Rho GEFs in NSCLC will inspire researchers to investigate the distinct roles of Rho GEFs in cancers, in order to provide critical strategies in clinical practice.

Rho GTPases in cancer radiotherapy and metastasis

Despite treatment advances, radioresistance and metastasis markedly impair the benefits of radiotherapy to patients with malignancies. Functioning as molecular switches, Rho guanosine triphosphatases (GTPases) have well-recognized roles in regulating various downstream signaling pathways in a wide range of cancers. In recent years, accumulating evidence indicates the involvement of Rho GTPases in cancer radiotherapeutic efficacy and metastasis, as well as radiation-induced metastasis. The functions of Rho GTPases in radiotherapeutic efficacy are divergent and context-dependent; thereby, a comprehensive integration of their roles and correlated mechanisms is urgently needed. This review integrates current evidence supporting the roles of Rho GTPases in mediating radiotherapeutic efficacy and the underlying mechanisms. In addition, their correlations with metastasis and radiation-induced metastasis are discussed. Under the prudent application of Rho GTPase inhibitors based on critical evaluations of biological contexts, targeting Rho GTPases can be a promising strategy in overcoming radioresistance and simultaneously reducing the metastatic potential of tumor cells.

Rho GTPases: Promising candidates for overcoming chemotherapeutic resistance

Despite therapeutic advances, resistance to chemotherapy remains a major challenge to patients with malignancies. Rho GTPases are essential for the development and progression of various diseases including cancer, and a vast number of studies have linked Rho GTPases to chemoresistance. Therefore, understanding the underlying mechanisms can expound the effects of Rho GTPases towards chemotherapeutic agents, and targeting Rho GTPases is a promising strategy to downregulate the chemo-protective pathways and overcome chemoresistance. Importantly, exceptions in certain biological conditions and interactions among the members of Rho GTPases should be noted. In this review, we focus on the role of Rho GTPases, particularly Rac1, in regulating chemoresistance and provide an overview of their related mechanisms and available inhibitors, which may offer novel options for future targeted cancer therapy.

RHO Guanine Nucleotide Exchange Factors Predict Prognosis of Non-Small Cell Lung Cancer: A Comprehensive Bioinformatics Analysis.. [DOI: 10.21203/rs.3.rs-18164/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background: Conventionally, RHO GEFs are known as activators for RHO GTPases which promote tumorigenesis. However, the role of RHO GEFs in non-small cell lung cancer (NSCLC) remains largely unknown. Methods: A comprehensive bioinformatics analysis of protein structure, transcriptional expression, survival, methylation, mutation and gene-set enrichment data was performed using multiple databases. Results: Through the screening of 81 RHO GEFs for their expression profiles and correlations with survival, four of them are identified with strong significance for predicting the prognosis of NSCLC patients. The four RHO GEFs, namely ABR, PREX1, DOCK2 and DOCK4, are downregulated in NSCLC compared to normal tissue. The downregulation of ABR, PREX1, DOCK2 and DOCK4, which can be contributed by promoter methylation, is correlated with unfavorable prognosis. Moreover, the underexpression of the four key RHO GEFs upregulates MYC signaling and DNA repair pathways, leading to carcinogenesis and poor prognosis. Conclusions: The data unveil the unprecedented role of ABR, PREX1, DOCK2 and DOCK4 as tumor suppressor in NSCLC. The previously unnoticed functions of RHO GEFs in NSCLC will inspire researchers to investigate the distinct roles of RHO GEFs in cancers, in order to provide critical strategies in clinical practice.

[Trial vaginal delivery for women with previous cesarean section]

A retrospective analysis was made on 85 cases of trial labor after previous cesarean section (CS) and compared with 100 primiparous vaginal deliveries (as control) during the last 10 years. Oxytocin infusion has been used in 61 trial cases to induce and/or to accelerate labor, and valium, procaine and atropine administered during the labor process in 23 of them. 65 of the 85 cases (76.5%) successfully delivered through the vagina (VD group), while 20 cases (23.5%) had repeat CS following failure in trial labor (CS group), and 3 women had reatened uterine rupture. There was 1 neonatal death in the VD trial labor group. No obvious difference in the Apgar scores of newborns was found between the CS group and the controls, and the duration of the labor process was much shorter in the VD trial group than that in the primiparae (7.51 +/- 2.44 hrs vs. 9.10 +/- 3.75 hrs) (P < 0.01). This study indicated that following a previous uneventful transverse lower segment cesarean section, trial labor should be encouraged under supervision.