Ataxia telangiectasia and Rad3-related inhibition by AZD6738 enhances gemcitabine-induced cytotoxic effects in bladder cancer cells.

The ataxia telangiectasia and rad3-related-checkpoint kinase 1 (ATR-CHK1) pathway is involved in DNA damage responses in many cancer cells. ATR inhibitors have been used in clinical trials in combination with radiation or chemotherapeutics; however, their effects against bladder cancer remain unclear. Here, the efficacy of combining gemcitabine with the novel ATR inhibitor AZD6738 was investigated in vitro in three bladder cancer cell lines (J82, T24, and UM-UC-3 cells). The effects of gemcitabine and AZD6738 on cell viability, clonogenicity, cell cycle, and apoptosis were examined. The combined use of gemcitabine and AZD6738 inhibited the viability and colony formation of bladder cancer cells compared to either treatment alone. Gemcitabine (5 nM) and AZD6738 (1 µM) inhibited cell cycle progression, causing cell accumulation in the S phase. Moreover, combined treatment enhanced cleaved poly[ADP-ribose]-polymerase expression alongside the number of annexin V-positive cells, indicating apoptosis induction. Mechanistic investigations showed that AZD6738 treatment inhibited the repair of gemcitabine-induced double-strand breaks by interfering with CHK1. Combining AZD6738 with gemcitabine could therefore be useful for bladder cancer therapy.

The Dual Histone Deacetylase-Proteasome Inhibitor RTS-V5 Acts Synergistically With Ritonavir to Induce Endoplasmic Reticulum Stress in Bladder Cancer Cells.

BACKGROUND/AIM: Simultaneous inhibition of histone deacetylase and proteasomes induces endoplasmic reticulum (ER) stress efficiently. RTS-V5 is the first dual histone deacetylase-proteasome inhibitor, and we anticipated that combining it with the cytochrome P450 family 3 subfamily A member 4 inhibitor ritonavir would enhance its activity in bladder cancer cells. MATERIALS AND METHODS: Using bladder cancer cells (human T-24, J-82, murine MBT-2), we evaluated the ability and mechanism by which the combination of RTS-V5 and ritonavir induced ER stress and killed cancer cells. RESULTS: The combination of RTS-V5 and ritonavir triggered robust apoptosis and inhibited bladder cancer growth effectively in vitro and in vivo. It caused ubiquitinated protein accumulation and induced ER stress synergistically. The combination inhibited the mammalian target of rapamycin pathway by increasing the expression of AMP-activated protein kinase. We also found that the combination caused histone and tubulin hyperacetylation. CONCLUSION: Ritonavir enhances the ability of RTS-V5 to cause ER stress in bladder cancer cells.

Ubiquitin-proteasome System Is a Promising Target for Killing Cisplatin-resistant Bladder Cancer Cells.

BACKGROUND/AIM: Activation of the ubiquitin-proteasome system (UPS) has been shown to be associated with drug resistance in cancer. Using bladder cancer cells, we investigated the association between UPS activation and cisplatin resistance and also the efficacy of UPS-targeting drugs. MATERIALS AND METHODS: We established cisplatin-resistant bladder cancer cells (J82-cisR, T24-cisR) and examined the activation status of the UPS and the efficacy of MLN7243, oprozomib, ixazomib, and RTS-V5. RESULTS: The UPS in cisplatin-resistant bladder cancer cells was activated compared to that in their parental controls. All the UPS-targeting drugs induced apoptosis and inhibited growth more effectively in the cisplatin-resistant bladder cancer cells than they did in the parental controls. Furthermore, these UPS-targeting drugs induced endoplasmic reticulum stress by causing unfolded protein accumulation at lower concentrations in the cisplatin-resistant bladder cancer cells. CONCLUSION: Targeting the UPS could be an effective strategy for treating cisplatin-resistant bladder cancer.

Simvastatin-romidepsin combination kills bladder cancer cells synergistically.

The HMG-CoA reductase inhibitor simvastatin activates AMP-activated protein kinase (AMPK) and thereby induces histone acetylation. We postulated that combining simvastatin with the histone deacetylase (HDAC) inhibitor romidepsin would kill bladder cancer cells by inducing histone acetylation cooperatively. The combination of romidepsin and simvastatin induced robust apoptosis and killed bladder cancer cells synergistically. In murine subcutaneous tumor models using MBT-2 cells, a 15-day treatment with 0.5 mg/kg romidepsin and 15 mg/kg simvastatin was well tolerated and inhibited tumor growth significantly. Mechanistically, the combination induced histone acetylation by activating AMPK. The combination also decreased the expression of HDACs, thus further promoting histone acetylation. This AMPK activation was essential for the combination's action because compound C, an AMPK inhibitor, suppressed the combination-induced histone acetylation and the combination's ability to induce apoptosis. We also found that the combination increased the expression of peroxisome proliferator-activated receptor (PPAR) γ, leading to reactive oxygen species production. Furthermore, the combination induced endoplasmic reticulum (ER) stress and this ER stress was shown to be associated with increased AMPK expression and histone acetylation, thus playing an important role in the combination's action. Our study also suggests there is a positive feedback cycle between ER stress induction and PPARγ expression.

Expressions of P-Glycoprotein, Multidrug Resistance Protein 1 and Annexin A2 as Predictive Factors for Intravesical Recurrence of Bladder Cancer after the Initial Transurethral Resection and Immediate Single Intravesical Instillation of Adriamycin.

OBJECTIVE: Immediate single instillation of chemotherapy following transurethral resection of bladder tumor (TURBT) is suggested for non-muscle invasive bladder cancer (NMIBC) patients. However, no study has evaluated molecular marker that was involved in intravesical recurrence (IVR) after single instillation of chemotherapy. Therefore, this study aimed to evaluate whether P-glycoprotein, multidrug resistance protein 1 (MRP1), Annexin A2 (ANXA2) or nucleophosmin (NPM) expression predicts IVR after initial TURBT and immediate single intravesical adriamycin instillation. METHODS: We retrospectively reviewed consecutive 443 patients who underwent TURBT. Of these, 54 patients who underwent initial TURBT and single instillation of adriamycin for NMIBC were included. The expressions of P-glycoprotein, MRP1, ANXA2 and NPM were evaluated immunohistochemically and were divided into 2 groups (low or high) according to the staining intensity and/or proportion of positive cells. IVR was assessed by Kaplan-Meier method. Cox`s multivaritate analyses were performed to identify independent predictors for IVR. RESULTS: Nineteen patients (35.1%) had IVR. High P-glycoprotein expression was significantly correlated with multiplicity, pT stage and high grade. High ANXA2 expression was significantly correlated with high grade. MRP1 and NPM were not correlated with any clinicopathological variables. MRP1 expression and ANXA2 expression were significantly correlated with P-glycoprotein expression. Patients with high P-glycoprotein expression had significantly worse IVR-free survival (IVRFS) than those with low P-glycoprotein expression (P =0.015). The difference in IVRFS rates between patients with high ANXA2 expression and those with low ANXA2 expression was nearly significant (P =0.057). Univariate analyses indicated multiplicity, high grade and high P-glycoprotein expression were significant predictors for IVR. Multivariate analysis indicated high grade was an independent predictor for IVR. CONCLUSIONS: High P-glycoprotein expression was associated with IVR. Further study was needed to determine significance of P-glycoprotein expression in IVR after single intravesical adriamycin instillation.

Inhibition of checkpoint kinase 1 potentiates anticancer activity of gemcitabine in bladder cancer cells.

Checkpoint kinases (CHKs) are involved in the DNA damage response in many cancer cells. CHK inhibitors have been used in clinical trials in combination with chemotherapeutics; however, their effect against bladder cancer remains unclear. Here, we investigated the efficacy of combining gemcitabine with MK-8776, a novel CHK1 inhibitor, in four bladder cancer cell lines. The effects of gemcitabine and MK-8776 on cell viability, clonogenicity, cell cycle, and apoptosis were examined alongside in vivo efficacy using murine xenograft tumor models. Combined treatment inhibited the viability and colony formation of bladder cancer cells compared to either single treatment. Although gemcitabine (10 nM) alone increased the cell number in S-phase, it increased the cell number in sub-G1 phase when combined with MK-8776 (0.5 µM). Combined treatment enhanced cleaved poly[ADP-ribose]-polymerase expression alongside the number of annexin-V-positive cells, indicating the induction of apoptosis. In vivo, administration of gemcitabine and MK-8776 was well tolerated and suppressed tumor growth. Mechanistically, the combined treatment elevated γH2A.X and suppressed Rad51 expression. Our study demonstrates that MK-8776 and gemcitabine combined induces apoptosis and suppresses proliferation in bladder cancer cells by inhibiting CHKs and DNA repair. Therefore, CHK1 inhibition combined with gemcitabine may be a potential treatment for bladder cancer.

Effect of increased expression of both ras-related C3 botulinum toxin substrate 1 and p21-activated kinase 1 in patients with N0M0 upper urinary tract urothelial carcinoma and cancer-free surgical margins.

BACKGROUND: As a member of the Rho small guanosine triphosphatase family, ras-related C3 botulinum toxin substrate 1 (RAC1) interacts with various specific effectors, and p21-activated kinase 1 (PAK1), which has a role in both carcinogenesis and cellular invasion, binds to RAC1, after which activated PAK1 regulates cellular functions. There have been few reports about the simultaneous analysis of RAC1 and its downstream effector PAK1 in upper urinary tract urothelial carcinoma (UTUC). We assessed the expressions of both RAC1 and PAK1 and evaluated their association with clinicopathological parameters. METHODS: Immunohistochemical studies of RAC1 or PAK1 were performed with specimens from 104 patients with N0M0 UTUC and cancer-free surgical margins. Correlation of the positive expression of RAC1 or PAK1 or both with clinicopathological parameters was evaluated. RESULTS: A hazard model showed that the presence of mixed histologic features and moderate or strong positive expression of both RAC1 and PAK1 were independent factors for shortened disease-specific survival time (Ps = 0.041 and 0.016, respectively), and another hazard model revealed that only moderate or strong positive expression of both RAC1 and PAK1 was an independent factor for shortened recurrence-free survival time in the multivariate analysis (P = 0.036). Neither moderate or strong positive expression of RAC1 alone nor moderate or strong positive expression of PAK1 alone was an independent factor for a worse rate of disease-specific or recurrence-free survival in multivariate analysis. CONCLUSIONS: Patients with N0M0 UTUC, cancer-free surgical margins and moderate or strong positive expression of both RAC1 and PAK1 should be carefully monitored after surgery.

Fluvastatin potentiates anticancer activity of vorinostat in renal cancer cells.

Drug repositioning is an emerging approach to developing novel cancer treatments. Vorinostat is a histone deacetylase inhibitor approved for cancer treatment, but it could attenuate its anticancer activity by activating the mTOR pathway. The HMG-CoA reductase inhibitor fluvastatin reportedly activates the mTOR inhibitor AMP-activated protein kinase (AMPK), and we thought that it would potentiate vorinostat's anticancer activity in renal cancer cells. The combination of vorinostat and fluvastatin induced robust apoptosis and inhibited renal cancer growth effectively both in vitro and in vivo. Vorinostat activated the mTOR pathway, as evidenced by the phosphorylation of ribosomal protein S6, and fluvastatin inhibited this phosphorylation by activating AMPK. Fluvastatin also enhanced vorinostat-induced histone acetylation. Furthermore, the combination induced endoplasmic reticulum (ER) stress that was accompanied by aggresome formation. We also found that there was a positive feedback cycle among AMPK activation, histone acetylation, and ER stress induction. This is the first study to report the beneficial combined effect of vorinostat and fluvastatin in cancer cells.

Lopinavir-Ritonavir Combination Induces Endoplasmic Reticulum Stress and Kills Urological Cancer Cells.

BACKGROUND/AIM: Induction of endoplasmic reticulum (ER) stress is a novel approach to cancer treatment. This study investigated the ability of the clinically feasible combination of the human immunodeficiency virus protease inhibitors lopinavir and ritonavir to induce ER stress killing urological cancer cells. MATERIALS AND METHODS: Renal cancer cells (769-P, 786-O) and bladder cancer cells (UMUC-3, T-24) were used to investigate the ability of the combination to induce ER stress and its mechanism of action. RESULTS: The combination inhibited the growth of both renal and bladder cancer cells synergistically by inducing ER stress. The combination-induced ER stress increased the expression of AMP-activated protein kinase and suppressed the mammalian target of rapamycin pathway. It also increased the expression of a tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor and thereby sensitized the cancer cells to TRAIL. CONCLUSION: The combination of lopinavir and ritonavir acts against urological cancer cells by inducing ER stress synergistically.

Metformin Augments Panobinostat's Anti-Bladder Cancer Activity by Activating AMP-Activated Protein Kinase.

Panobinostat, a histone deacetylase inhibitor, induces histone acetylation and acts against cancer but attenuates its anticancer activity by activating the mammalian target of rapamycin (mTOR) pathway. AMP-activated protein kinase (AMPK) is a cellular energy sensor that reportedly inhibits the mTOR pathway. The antidiabetic drug metformin is also a potent AMPK activator and we investigated whether it augmented panobinostat's antineoplastic activity in bladder cancer cells (UMUC3, J82, T24 and MBT-2). Metformin enhanced panobinostat-induced apoptosis and the combination inhibited the growth of bladder cancer cells cooperatively in vitro and in vivo. As expected, metformin increased the phosphorylation of AMPK and decreased the panobinostat-caused phosphorylation of S6 ribosomal protein, thus inhibiting the panobinostat-activated mTOR pathway. The AMPK activation was shown to play a pivotal role in the combination's action because the AMPK inhibitor compound C attenuated the combination's anticancer activity. Furthermore, the AMPK activation by metformin enhanced panobinostat-induced histone and non-histone acetylation. This acetylation was especially remarkable in the proteins in the detergent-insoluble fraction, which would be expected if the combination also induced endoplasmic reticulum stress.

Panobinostat and Nelfinavir Inhibit Renal Cancer Growth by Inducing Endoplasmic Reticulum Stress.

BACKGROUND/AIM: There is no curative treatment for patients with advanced renal cancer. We believed that the combination of the histone deacetylase inhibitor panobinostat and the human immunodeficiency virus protease inhibitor nelfinavir would kill renal cancer cells by inducing endoplasmic reticulum (ER) stress. MATERIALS AND METHODS: Using renal cancer cells (769-P, 786-O, Caki-2), the ability of this combination to induce ER stress and its mechanism of action were investigated. RESULTS: The combination of drugs induced apoptosis and inhibited cancer growth effectively both in vitro and in vivo. Mechanistically, the combination induced ER stress and histone acetylation cooperatively. ER stress induction was shown to play a pivotal role in the anticancer effect of the combination because the protein synthesis inhibitor cycloheximide significantly attenuated combination-induced apoptosis. Nelfinavir was also found to increase the expression of the mammalian target of rapamycin (mTOR) inhibitor AMP-activated protein kinase (AMPK) and inhibited the panobinostat-activated mTOR pathway. CONCLUSION: Panobinostat and nelfinavir inhibit renal cancer growth by inducing ER stress.

Evaluation of Therapeutic Potential of Phenoxodiol, a Novel Isoflavone Analog, in Renal Cancer Cells.

BACKGROUND/AIM: In the present study, the antineoplastic activity and mechanism of action of phenoxodiol, a novel isoflavone analog, was investigated in renal cancer cells. MATERIALS AND METHODS: A panel of renal cancer cells (769-P, 786-O, Caki-2) was treated with phenoxodiol in vitro, and the efficacy of treatment was evaluated. RESULTS: MTS assay results showed that phenoxodiol decreased renal cancer viability in a dose-dependent manner. In addition, it inhibited colony formation significantly and perturbed the cell cycle. Treatment with phenoxodiol increased the number of annexin-V-positive cells as well as the expression of cleaved poly ADP ribose polymerase, demonstrating that phenoxodiol induced apoptosis in renal cancer cells. Phenoxodiol also inhibited Akt pathway via dephosphorylation of Akt. CONCLUSION: Phenoxodiol inhibited Akt pathway and induced apoptosis of renal cancer cells. The present study provides a theoretical basis for future development of a novel therapy effective against renal cancer.

Nelfinavir Induces Endoplasmic Reticulum Stress and Sensitizes Renal Cancer Cells to TRAIL.

BACKGROUND/AIM: Induction of endoplasmic reticulum (ER) stress is a novel strategy for cancer treatment. The human immunodeficiency virus protease inhibitor nelfinavir was recently shown to induce ER stress, but its anti-neoplastic activity has never been investigated in renal cancer, as far as we are aware. MATERIALS AND METHODS: Using renal cancer cells (769-P, 786-O, Caki-2), the ability of nelfinavir to induce ER stress and sensitize them to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was tested. RESULTS: Nelfinavir caused apoptosis and inhibited renal cancer growth in a dose-dependent fashion. It also suppressed colony formation significantly. Nelfinavir induced ER stress and increased the expression of TRAIL death receptor (DR) 4 and DR5, sensitizing the cancer cells to TRAIL. This sensitization was blocked by human recombinant DR4/Fc and DR5/Fc chimeric protein, confirming that the sensitization was due to increased expression of both DR4 and DR5. CONCLUSION: Nelfinavir induces ER stress in renal cancer cells and sensitizes them to TRAIL.

Delanzomib Interacts with Ritonavir Synergistically to Cause Endoplasmic Reticulum Stress in Renal Cancer Cells.

BACKGROUND/AIM: To investigate the efficacy against renal cancer cells of combining the HIV protease inhibitor ritonavir with the novel proteasome inhibitor delanzomib. MATERIALS AND METHODS: Renal cancer cell lines 769-P, 786-O, Caki-2 and Renca were treated with ritonavir and delanzomib in vitro and in vivo, and the efficacy of combination was evaluated. RESULTS: The combination of ritonavir and delanzomib synergistically inhibited renal cancer growth and suppressed colony formation. It induced robust apoptosis evidenced by increased cell population in the sub-G1 fraction and increased number of annexin-V-positive cells. A 13-day treatment with the combination was well tolerated in the mouse model and inhibited tumor growth significantly. Mechanistically, the combination synergistically induced endoplasmic reticulum stress and inhibited the mammalian target of rapamycin (mTOR) pathway. CONCLUSION: The effectiveness of combination of ritonavir and delanzomib appears to be due to the induction of ER stress and inhibition of the mTOR pathway.

Nelfinavir and Ritonavir Kill Bladder Cancer Cells Synergistically by Inducing Endoplasmic Reticulum Stress.

The human immunodeficiency virus (HIV) protease inhibitor nelfinavir acts against malignancies by inducing endoplasmic reticulum (ER) stress. The HIV protease inhibitor ritonavir, on the other hand, not only induces ER stress but also inhibits P-glycoprotein's pump activity and thereby enhances the effects of its substrate drugs. We therefore postulated that ritonavir in combination with nelfinavir would kill bladder cancer cells effectively by inducing ER stress cooperatively and also enhancing nelfinavir's effect. Nelfinavir was shown to be a P-glycoprotein substrate, and the combination of nelfinavir and ritonavir inhibited bladder cancer cell growth synergistically. It also suppressed colony formation significantly. The combination significantly increased the number of cells in the sub-G1 fraction and also the number of annexin V+ cells, confirming robust apoptosis induction. The combination induced ER stress synergistically, as evidenced by the increased expression of glucose-regulated protein 78, ER-resident protein 44, and endoplasmic oxidoreductin-1-like protein. It also increased the expression of the mammalian target of rapamycin (mTOR) inhibitor AMP-activated protein kinase and caused dephosphorylation of S6 ribosomal protein, demonstrating that the combination also inhibited the mTOR pathway. We also found that the combination enhanced histone acetylation synergistically by decreasing the expression of HDACs 1, 3, and 6.

Docosahexaenoic acid inhibits the phosphorylation of STAT3 and the growth and invasion of renal cancer cells.

Docosahexaenoic acid (DHA) has a variety of anti-tumor activities. The present study examined the anti-tumor activity of DHA in renal cancer cells and its underlying mechanisms of action. The effects of DHA on the viability and proliferation of the human renal cancer cell lines Caki-1 and 786-O were examined by an MTS assay and cell counting. In addition, cell cycle distribution and cell apoptosis were analyzed by flow cytometry and Annexin V staining, and modulation of cell mobility and invasiveness was assessed by wound healing and Matrigel invasion assays. Effects of DHA on intracellular signaling pathways were also analyzed by western blotting. It was observed that DHA significantly reduced the viability and proliferation of Caki-1 and 786-O cells (P<0.01). Specifically, there were increases in the sub-G1 and G2/M cell populations, as well as the percentages of cells exhibiting Annexin-positive and propidium-iodide-negative staining. In addition, the covered area in a wound and the number of cells invading through a Matrigel chamber decreased when Caki-1 or 786-O cells were treated with DHA. Phosphorylation of epidermal growth factor receptor was also upregulated following DHA treatment, while phosphorylation of signal transducer and activator of transcription 3 and Akt was downregulated. Collectively, these data suggest that DHA may be useful in the treatment of renal cell carcinoma.

STAT3 inhibition by WP1066 suppresses the growth and invasiveness of bladder cancer cells.

Signal transducer and activator of transcription 3 (STAT3) regulates the expression of genes mediating cell survival, proliferation and angiogenesis and is aberrantly activated in various types of malignancies, including bladder cancer. We examined whether it could be a novel therapeutic target for bladder cancer using the STAT3 inhibitor WP1066. In T24 and UMUC-3 bladder cancer cells, 5 µM WP1066 prevented the phosphorylation of STAT3 and 2.5 µM WP1066 decreased cell survival and proliferation significantly (P<0.01). WP1066 also induced apoptosis accompanied by the suppression of the expression of Bcl-2 and Bcl-xL in T24 cells. Moreover, the covered area in a wound and the number of cells invading through a Matrigel chamber decreased significantly (P<0.01) when cells were treated with WP1066. The activities of MMP-2 and MMP-9 were also decreased by treatment with 10 µM WP1066. Our results revealed that using WP1066 to inhibit the STAT3 signaling pathway suppressed the viability and invasiveness of bladder cancer cells effectively and could be a novel therapeutic strategy against bladder cancer.

Ritonavir and ixazomib kill bladder cancer cells by causing ubiquitinated protein accumulation.

There is no curative treatment for advanced bladder cancer. Causing ubiquitinated protein accumulation and endoplasmic reticulum stress is a novel approach to cancer treatment. The HIV protease inhibitor ritonavir has been reported to suppress heat shock protein 90 and increase the amount of unfolded proteins in the cell. If the proteasome functions normally, however, they are rapidly degraded. We postulated that the novel proteasome inhibitor ixazomib combined with ritonavir would kill bladder cancer cells effectively by inhibiting degradation of these unfolded proteins and thereby causing ubiquitinated proteins to accumulate. The combination of ritonavir and ixazomib induced drastic apoptosis and inhibited the growth of bladder cancer cells synergistically. The combination decreased the expression of cyclin D1 and cyclin-dependent kinase 4, and increased the sub-G1 fraction significantly. Mechanistically, the combination caused ubiquitinated protein accumulation and endoplasmic reticulum stress. The combination-induced apoptosis was markedly attenuated by the protein synthesis inhibitor cycloheximide, suggesting that the accumulation of ubiquitinated proteins played an important role in the combination's antineoplastic activity. Furthermore, the combination induced histone acetylation cooperatively and the decreased expression of histone deacetylases was thought to be one mechanism of this histone acetylation. The present study provides a theoretical basis for future development of novel ubiquitinated-protein-accumulation-based therapies effective against bladder cancer.

Progression of Human Renal Cell Carcinoma via Inhibition of RhoA-ROCK Axis by PARG1.

Renal cell carcinoma (RCC) is the most lethal urological malignancy with high risk of recurrence; thus, new prognostic biomarkers are needed. In this study, a new RCC antigen, PTPL1 associated RhoGAP1 (PARG1), was identified by using serological identification of recombinant cDNA expression cloning with sera from RCC patients. PARG1 protein was found to be differentially expressed in RCC cells among patients. High PARG1 expression is significantly correlated with various clinicopathological factors relating to cancer cell proliferation and invasion, including G3 percentage (P = .0046), Ki-67 score (p expression is also correlated with high recurrence of N0M0 patients (P = .0084) and poor prognosis in RCC patients (P = .0345). Multivariate analysis has revealed that high PARG1 expression is an independent factor for recurrence (P = .0149) of N0M0 RCC patients. In in vitro studies, depletion of PARG1by siRNA in human RCC cell lines inhibited their proliferation through inducing G1 cell cycle arrest via upregulation of p53 and subsequent p21Cip1/Waf1, which are mediated by increased RhoA-ROCK activities. Similarly, PARG1 depletion cells inhibited invasion ability via increasing RhoA-ROCK activities in the RCC cell lines. Conversely, overexpression of PARG1 on human embryonic kidney cell line HEK293T promotes its cell proliferation and invasion. These results indicate that PARG1 plays crucial roles in progression of human RCC in increasing cell proliferation and invasion ability via inhibition of the RhoA-ROCK axis, and PARG1 is a poor prognostic marker, particularly for high recurrence of N0M0 RCC patients.