RAC3 Inhibition Induces Autophagy to Impair Metastasis in Bladder Cancer Cells via the PI3K/AKT/mTOR Pathway

Abstract

BackgroundBladder cancer (BCa) is one of the most frequent malignant tumors globally, with a significant morbidity and mortality rate. Gene expression dysregulation has been proven to play a critical role in tumorigenesis. Ras-related C3 botulinum toxin substrate3 (RAC3), which is overexpressed in several malignancies and promotes tumor progression, has been identified as an oncogene. However, RAC3 has important but not fully understood biological functions in cancer. Our research aims to reveal the new functions and potential mechanisms of RAC3 involved in BCa progression.MethodsWe explored the expression level of RAC3 and its relationship with prognosis by publicly accessible BCa datasets, while the correlation of RAC3 expression with clinicopathological variables of patients was analyzed. In vitro and in vivo proliferation, migration, autophagy, and other phenotypic changes were examined by constructing knockdown(KD)/overexpression(OE) RAC3 cells and their association with PI3K/AKT/mTOR pathway was explored by adding autophagy-related compounds.ResultsCompared with non-tumor samples, RAC3 was highly expressed in BCa and negatively correlated with prognosis. KD/OE RAC3 inhibited/promoted the proliferation and migration of BCa cells. Knockdown RAC3 caused cell cycle arrest and decreased adhesion without affecting apoptosis. Inhibition of RAC3 activates PI3K/AKT/mTOR mediated autophagy and inhibits proliferation and migration of BCa cells in vivo and in vitro. Autophagy inhibitor 3MA can partially rescue the metastasis and proliferation inhibition effect caused by RAC3 inhibition. Inhibit/activate mTOR enhanced/impaired autophagy, resulting in shRAC3-mediated migration defect exacerbated/rescued.ConclusionRAC3 is highly expressed in BCa. It is associated with advanced clinicopathological variables and poor prognosis. Knockdown RAC3 exerts an antitumor effect by enhancing PI3K/AKT/mTOR mediated autophagy. Targeting RAC3 and autophagy simultaneously is a potential therapeutic strategy for inhibiting BCa progression and prolonging survival.

Survival-Associated Cellular Response Maintained in Pancreatic Ductal Adenocarcinoma (PDAC) Switched Between Soft and Stiff 3D Microgel Culture

“…Figure b shows similar gene expression profiles for (i) cells cultured in stiff 3D conditions (“stiff to stiff”) and cells moved from stiff to soft 3D culture (“stiff to soft”) and (ii) cells cultured in soft 3D conditions (“soft to soft”) and cells moved from soft to stiff 3D culture (“soft to stiff”). Remarkably, the top three downregulated genes in conditions where cells experienced a stiff 3D microenvironment for any length of time were tumor suppressor genes LATS1 , BCAR3 , and CDKN2C . − Of the top upregulated genes in stiff-primed conditions (log 2 fold-change >2, p -value < 0.05), several of these genes have been identified as prognostic markers in cancer, including SLC6A4 , MACC1 , SLC14A2 , CRB3 , NFKBIL1 , RAC3 , CLIC3 , CYBA , FRMD6-AS1 , LAIR1 , L1TD1 , SEMA3E , PCDH11Y , MIRLET7BHG , and TERC (Figure b). − We performed GO Term analysis comparing cells primed in soft culture vs cells primed in stiff culture and note changes in terms including transcriptional misregulation in cancer, chromatin organization, nucleus organization, and metabolism of RNA, which may suggest epigenetic mechanisms act as a component responsible for some of these transcriptional changes (Figure S9). For the genes that may be correlated with mechanical memory, we examined TCGA for pancreatic cancer patient prognosis data .…”

Cancer-associated fibroblasts promote migration and invasion of non-small cell lung cancer cells via METTL3-mediated RAC3 m6A modification

“…Numerous studies have shown that RAC3 is involved in tumor invasion and metastasis 25 , 26 , which drove us to further investigate whether RAC3 played a role in NSCLC cells migration. When RAC3 was knocked down in lung cancer cells, the enhanced migration by CAFs was diminished.…”

“…RAC3 is highly expressed in bladder cancer cells, and stimulates proliferation and migration of bladder cancer cells via PYCR1-mediated JAK/STAT pathway activation 26 . Interestingly, when RAC3 was knocked down, the growth and migration of bladder cancer cells were inhibited through the PI3K/AKT/mTOR pathway-mediated autophagy induction 25 . RAC3 inhibition also caused a significant reduction of both invasion and adhesion of breast cancer cells through the ERK-2/NF-κB signaling pathway 41 .…”

Predicting Bladder Cancer Survival with High Accuracy: Insights from MAPK Pathway-related Genes

“…Among the 10 model genes, RAC3 stands out as one of the three isoforms within the Rho GTPase subfamily 29,30 . Studies have demonstrated that RAC3 enhances tumor cell proliferation, migration, and invasion by activating the JAK/STAT signaling pathway 31,32 . Furthermore, high expression of RAC3 predicts a poor prognosis of BLCA 33 .…”