Fibroblast growth factor receptor inhibitor erdafitinib promotes Mcl-1 degradation and synergistically induces apoptosis with Bcl-xL/Bcl-2 inhibitor in urothelial cancer cells.

Metastatic urothelial cancer is a lethal disease. Although recent advances in immunotherapies and targeted therapy against fibroblast growth factor receptor (FGFR)2/3 mutation (erdafitinib) have improved patient survival, there is still a critical need for novel therapeutic strategies for patients who do not benefit from these treatments. Evasion of apoptosis through amplifying anti-apoptotic Bcl-2 family proteins (Mcl-1, Bcl-xL, Bcl-2) is one mechanism responsible for treatment resistance in urothelial cancers, suggesting that targeting anti-apoptotic proteins may be a possible therapeutic strategy for urothelial cancers. Here, we showed that erdafitinib increased Mcl-1 degradation mainly through previously unknown mechanisms and synergized with a BH3 mimetic drug targeting Bcl-xL/Bcl-2 to induce apoptosis in FGFR wild-type urothelial cancer cells. Strikingly, clinical sequencing data showed amplification of MCL1 or BCL2L1 (encoding Bcl-xL) in subsets of FGFR mutation-negative bladder cancer tissues. In conclusion, these findings suggest that exploiting apoptosis pathways may be a promising treatment strategy for patients with FGFR wild-type metastatic urothelial cancer with Mcl-1 or Bcl-xL overexpression.

Identification of BCL-XL as highly active survival factor and promising therapeutic target in colorectal cancer.

Since metastatic colorectal cancer (CRC) is a leading cause of cancer-related death, therapeutic approaches overcoming primary and acquired therapy resistance are an urgent medical need. In this study, the efficacy and toxicity of high-affinity inhibitors targeting antiapoptotic BCL-2 proteins (BCL-2, BCL-XL, and MCL-1) were evaluated. By RNA sequencing analysis of a pan-cancer cohort comprising >1500 patients and subsequent prediction of protein activity, BCL-XL was identified as the only antiapoptotic BCL-2 protein that is overactivated in CRC. Consistently, pharmacologic and genetic inhibition of BCL-XL induced apoptosis in human CRC cell lines. In a combined treatment approach, targeting BCL-XL augmented the efficacy of chemotherapy in vitro, in a murine CRC model, and in human ex vivo derived CRC tissue cultures. Collectively, these data show that targeting of BCL-XL is efficient and safe in preclinical CRC models, observations that pave the way for clinical translation.

Sequential combinations of chemotherapeutic agents with BH3 mimetics to treat rhabdomyosarcoma and avoid resistance.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in childhood and adolescence. Refractory/relapsed RMS patients present a bad prognosis that combined with the lack of specific biomarkers impairs the development of new therapies. Here, we utilize dynamic BH3 profiling (DBP), a functional predictive biomarker that measures net changes in mitochondrial apoptotic signaling, to identify anti-apoptotic adaptations upon treatment. We employ this information to guide the use of BH3 mimetics to specifically inhibit BCL-2 pro-survival proteins, defeat resistance and avoid relapse. Indeed, we found that BH3 mimetics that selectively target anti-apoptotic BCL-xL and MCL-1, synergistically enhance the effect of clinically used chemotherapeutic agents vincristine and doxorubicin in RMS cells. We validated this strategy in vivo using a RMS patient-derived xenograft model and observed a reduction in tumor growth with a tendency to stabilization with the sequential combination of vincristine and the MCL-1 inhibitor S63845. We identified the molecular mechanism by which RMS cells acquire resistance to vincristine: an enhanced binding of BID and BAK to MCL-1 after drug exposure, which is suppressed by subsequently adding S63845. Our findings validate the use of DBP as a functional assay to predict treatment effectiveness in RMS and provide a rationale for combining BH3 mimetics with chemotherapeutic agents to avoid tumor resistance, improve treatment efficiency, and decrease undesired secondary effects.

Action of Akt Pathway on La-Induced Hippocampal Neuron Apoptosis of Rats in the Growth Stage.

This study investigated the influences of lanthanum (La) exposure on learning and memory and the expression of apoptosis-related proteins in offspring rats. Wistar female rats were randomly divided into a control group (NC) and 0.25%, 0.5% and 1.0% LaCl3 treatment groups, with eight per group. La dye was transmitted to offspring rats through parental blood circulation and breast milk before delactation and through water drinking after delectation. Offspring rats were killed at 14, 28 and 42 days after birth. Hippocampal neurons were observed by microscope, and apoptosis and necrosis were tested. The expression levels of apoptosis-related proteins were detected by Western blot, and Morris water maze experiments were used to measure learning and memory abilities. LaCl3 groups showed longer escape latency periods and swimming distances than the NC group (p < 0.05). The 1.0% LaCl3 group passed across the target quadrants and platforms more times and stayed in the target quadrants for less time, than the NC group (p < 0.05). At 42 days, the apoptosis rate and necrosis in the hippocampus of the 1.0% LaCl3 group were significantly higher than those of other groups. There was a significant difference among LaCl3 groups in terms of protein expressions measured in the hippocampus. In LaCl3 groups, caspase-3 and caspase-9 were significantly higher than in the NC group (p < 0.05). Therefore, La exposure can promote neuronal apoptosis by regulating the protein expressions of Akt, Bcl-2, Bcl-xl, Bax, Bad, caspase-3 and caspase-9, thus damaging learning and memory and the hippocampal neurons of offspring rats.

Bim, Puma and Noxa upregulation by Naftopidil sensitizes ovarian cancer to the BH3-mimetic ABT-737 and the MEK inhibitor Trametinib.

Ovarian cancer represents the first cause of mortality from gynecologic malignancies due to frequent chemoresistance occurrence. Increasing the [BH3-only Bim, Puma, Noxa proapoptotic]/[Bcl-xL, Mcl-1 antiapoptotic] proteins ratio was proven to efficiently kill ovarian carcinoma cells and development of new molecules to imbalance Bcl-2 member equilibrium are strongly required. Drug repurposing constitutes an innovative approach to rapidly develop therapeutic strategies through exploitation of established drugs already approved for the treatment of noncancerous diseases. This strategy allowed a renewed interest for Naftopidil, an α1-adrenergic receptor antagonist commercialized in Japan for benign prostatic hyperplasia. Naftopidil was reported to decrease the incidence of prostate cancer and its derivative was described to increase BH3-only protein expression in some cancer models. Based on these arguments, we evaluated the effects of Naftopidil on ovarian carcinoma and showed that Naftopidil reduced cell growth and increased the expression of the BH3-only proteins Bim, Puma and Noxa. This effect was independent of α1-adrenergic receptors blocking and involved ATF4 or JNK pathway depending on cellular context. Finally, Naftopidil-induced BH3-only members sensitized our models to ABT-737 and Trametinib treatments, in vitro as well as ex vivo, in patient-derived organoid models.

MCL1 inhibition is effective against a subset of small-cell lung cancer with high MCL1 and low BCL-XL expression.

There have been few advances in the treatment of small-cell lung cancer (SCLC) because of the lack of targets. MCL1, a member of the anti-apoptotic BCL-2 family, may be a treatment target in several cancers, including SCLC. However, whether the expression profile of the anti-apoptotic BCL-2 family affects MCL1 inhibition strategy is unknown. A tissue microarray (TMA) was created from consecutive patients who were diagnosed with SCLC and had previously undergone surgery at Kyoto University Hospital (Kyoto, Japan) between 2001 and 2017. We used S63845, a MCL1 inhibitor, to assess the cytotoxic capacity in SCLC cell lines including a patient-derived cell line in vitro and in vivo. The combination of S63845 with navitoclax, a double BCL-XL/BCL-2 inhibitor, was also employed to examine the comprehensive inhibition of the anti-apoptotic BCL-2 family. Immunohistochemistry of a TMA from patients with surgically resected SCLC demonstrated high MCL1 expression with low BCL-XL and BCL-2 to be the most common expression profile. S63845 was effective in high MCL1- and low BCL-XL-expressing SCLC cell lines. S63845 induced BAK-dependent apoptosis in vitro, and the anti-tumor efficacy was confirmed in an in vivo model. Although knockdown of BCL-XL and BCL-2 improved the cytotoxic activity of S63845 and its combination with navitoclax increased the anti-tumor cytotoxicity, the therapeutic range of S63845 with navitoclax was narrow in in vivo studies. Our study suggests MCL1 inhibition therapy be applied for high MCL1- and low BCL-XL-expressing SCLC patients.

Apoptosis signaling molecules as treatment targets in head and neck squamous cell carcinoma.

OBJECTIVES: To evaluate BCL-2 family signaling molecules in head and neck squamous cell carcinoma (HNSCC) and examine the ability of therapeutic agents with variable mechanisms of action to induce apoptosis in HNSCC cells. METHODS: messenger ribonculeic acid (mRNA) expression of BAK, BAX, B-cell lymphoma (Bcl-2), BCL2 Like 1 (BCL2L1), and MCL1 were measured in The Cancer Genome Atlas (TCGA) head and neck cancer dataset, as well as in a dataset from a cohort at Montefiore Medical Center (MMC). Protein expression was similarly evaluated in a panel of HNSCC cell lines (HN30, HN31, HN5, MDA686LN, UMSCC47). Cell viability and Annexin V assays were used to assess the efficacy and apoptotic potential of a variety of agents (ABT-263 [navitoclax], A-1210477, and bortezomib. RESULTS: Expression of BAK, BAX, BCL2L1, and MCL1 were each significantly higher than expression of BCL2 in the TCGA and MMC datasets. Protein expression demonstrated the same pattern of expression when examined in HNSCC cell lines. Treatment with combined ABT-263 (navitoclax)/A-1210477 or with bortezomib demonstrated apoptosis responses that approached or exceeded treatment with staurospaurine control. CONCLUSION: HNSCC cells rely on inhibition of apoptosis via BCL-xL and MCL-1 overexpression, and induction of apoptosis remains a potential therapeutic option as long as strategies overcome redundant anti-apoptotic signals. LEVEL OF EVIDENCE: NA Laryngoscope, 130:2643-2649, 2020.

PTPσ inhibitors promote hematopoietic stem cell regeneration.

Receptor type protein tyrosine phosphatase-sigma (PTPσ) is primarily expressed by adult neurons and regulates neural regeneration. We recently discovered that PTPσ is also expressed by hematopoietic stem cells (HSCs). Here, we describe small molecule inhibitors of PTPσ that promote HSC regeneration in vivo. Systemic administration of the PTPσ inhibitor, DJ001, or its analog, to irradiated mice promotes HSC regeneration, accelerates hematologic recovery, and improves survival. Similarly, DJ001 administration accelerates hematologic recovery in mice treated with 5-fluorouracil chemotherapy. DJ001 displays high specificity for PTPσ and antagonizes PTPσ via unique non-competitive, allosteric binding. Mechanistically, DJ001 suppresses radiation-induced HSC apoptosis via activation of the RhoGTPase, RAC1, and induction of BCL-XL. Furthermore, treatment of irradiated human HSCs with DJ001 promotes the regeneration of human HSCs capable of multilineage in vivo repopulation. These studies demonstrate the therapeutic potential of selective, small-molecule PTPσ inhibitors for human hematopoietic regeneration.

Fipronil induces apoptosis and cell cycle arrest in porcine oocytes during in vitro maturation.

Fipronil (FPN) is a widely used phenylpyrazole pesticide that can kill pests by blocking γ-aminobutyric acid (GABA)-gated chloride channels. In addition, there are lack of studies on the effects of FPN on the female mammalian gametes. In this study, porcine oocytes were used to investigate the effects of FPN on the oocyte maturation process. The results showed that the first polar body extrusion rate significantly decreased (100 µM FPN vs. control, 18.64 ± 2.95% vs. 74.90 ± 1.50%, respectively), and oocytes were arrested at the germinal vesicle stage in 100 µM FPN group. Meanwhile, the FPN caused a significant increase in reactive oxygen species (ROS) levels and severe DNA damage inside the oocytes. Furthermore, apoptosis was enhanced along with decreases in mitochondrial membrane potential, BCL-xL, and the release of cytochrome C in FPN-treated group. Additionally, low CDK1 activity and delayed cyclin B1 degradation during germinal vesicle breakdown were found in the FPN-treated group, which resulted from the activation of ATM-P53-P21 pathway. In conclusion, FPN induces apoptosis and cell cycle arrest in porcine oocyte maturation because of increased ROS levels and DNA damage. This suggests that the FPN in the environment may have potential detrimental effects on the female mammalian reproductive system.

Aspirin induces oncosis in tumor cells.

In contrast to the well-known anti-tumor mechanisms of aspirin in inducing apoptosis or autophagy, we here for the first time report oncosis induced by aspirin in tumor cells. In vitro and in vivo analysis showed that aspirin induced compromised Bcl-XL level and subsequent ATP depletion. Overexpression of CFP-Bcl-XL in Hela and A549 cells observably inhibited aspirin-induced ATP depletion and almost completely inhibited the aspirin-induced cells bubbling, while pharmacological inhibition of endogenous Bcl-XL activity by ABT-737 remarkably promoted aspirin-induced ATP depletion and cells bubbling, suggesting the key inhibitory role of Bcl-XL in aspirin-induced oncosis. Overexpression of Bax/Bad significantly promoted aspirin-induced oncosis. In addition, cells cultured in a glucose-free medium with low ATP level exhibited higher percentage of bubbling cells than the cells cultured in a glucose medium with high ATP level under aspirin treatment, indicating the important role of ATP depletion in aspirin-induced oncosis. Furthermore, caspase-3 was demonstrated to be not involved in aspirin-induced oncosis. Animal studies showed that aspirin treatment significantly inhibited tumors growth, but did not induce toxicities to mice. Collectively, aspirin inhibits tumors growth in mice and induces oncosis in which the compromised Bcl-XL and intracellular ATP depletion play a dominant role, which provides insights into the therapeutic strategy of aspirin in oncology.

Adjunctive Chinese herbal medicine therapy for nasopharyngeal carcinoma: Clinical evidence and experimental validation.

BACKGROUND: To investigate the benefits of adjunctive Chinese herbal medicine (CHM) for patients with nasopharyngeal carcinoma (NPC). METHODS: We included all patients diagnosed with NPC during 1997-2009 and followed until 2011 in Taiwan. We used 1:1 frequency matching by age, sex, comorbidity, conventional treatment, and index year to compare the CHM users and non-CHM users (n = 2542 each). The prescribed CHM was further investigated with regard to its cytotoxicity. RESULTS: Compared with non-CHM users, adjunctive CHM users had a lower hazard ratio of mortality risk, and a better survival probability. Gan-Lu-Yin (GLY) was the most commonly prescribed CHM, and it reduced cell viability, inhibited tumor proliferation, and induced apoptosis through the poly (ADP-ribose) polymerase and caspase-3-dependent pathway in human NPC TW01 cells. Oral administration of GLY retarded NPC-TW01 tumor growth in the xenograft nude mouse model. CONCLUSION: Real-world data and laboratory experiments implied that adjunctive CHM might be beneficial for NPC patients.

Selective BH3-mimetics targeting BCL-2, BCL-XL or MCL-1 induce severe mitochondrial perturbations.

Induction of apoptosis by selective BH3-mimetics is currently investigated as a novel strategy for cancer treatment. Here, we report that selective BH3-mimetics induce apoptosis in a variety of hematological malignancies. Apoptosis is accompanied by severe mitochondrial toxicities upstream of caspase activation. Specifically, the selective BH3-mimetics ABT-199, A-1331852 and S63845, which target BCL-2, BCL-XL and MCL-1, respectively, induce comparable ultrastructural changes including mitochondrial swelling, a decrease of mitochondrial matrix density and severe loss of cristae structure. These shared effects on mitochondrial morphology indicate a similar function of these anti-apoptotic BCL-2 proteins in maintaining mitochondrial integrity and function.

The role of atenolol in the modulation of the expression of genes encoding pro- (caspase-1) and anti- (Bcl2L1) apoptotic proteins in endothelial cells exposed to intestinal ischemia and reperfusion in rats

Abstract Purpose: To investigate the role of atenolol in the gene expression of caspase 1 (Casp1) and Bcl2L1 on vascular endothelium of rat intestine after ischemia and reperfusion (IR). Methods: Eighteen adult male Wistar rats were randomly divided into 3 groups (n=6): SG (Sham group): no clamping of the superior mesenteric artery; IRG: IR plus saline group: IRG+At: IR plus Atenolol group. Rats from IRG and IRG+At were subjected to 60 min of intestinal ischemia and 120 min of reperfusion. Atenolol (2mg/kg) or saline were injected in the femoral vein 5 min before ischemia, 5 min and 55 min after reperfusion. Thereafter, intestinal segments were appropriately removed and processed for Endothelial Cell Biology Rat RT2 Profiler PCR Array. Results: the anti-apoptotic Bcl2L1 gene expression was significantly down-regulated (-1.10) in the IRG and significantly up-regulated in the IRG+At (+14.15). Meanwhile, despite Casp1 gene expression was upregulated in both groups, it was significantly higher in the IRG (+35.06) than the IRG+At (+6.68). Conclusions: Atenolol presents antiapoptotic effects on rat intestine subjected to IR partly by the up-regulation of the anti-apoptotic Bcl2L1 gene expression. Moreover, atenolol can mitigate the pro-apoptotic and pro-inflammatory effects of Casp1 gene on rat intestine after IR.

The role of atenolol in the modulation of the expression of genes encoding pro- (caspase-1) and anti- (Bcl2L1) apoptotic proteins in endothelial cells exposed to intestinal ischemia and reperfusion in rats.

PURPOSE: To investigate the role of atenolol in the gene expression of caspase 1 (Casp1) and Bcl2L1 on vascular endothelium of rat intestine after ischemia and reperfusion (IR). METHODS: Eighteen adult male Wistar rats were randomly divided into 3 groups (n=6): SG (Sham group): no clamping of the superior mesenteric artery; IRG: IR plus saline group: IRG+At: IR plus Atenolol group. Rats from IRG and IRG+At were subjected to 60 min of intestinal ischemia and 120 min of reperfusion. Atenolol (2mg/kg) or saline were injected in the femoral vein 5 min before ischemia, 5 min and 55 min after reperfusion. Thereafter, intestinal segments were appropriately removed and processed for Endothelial Cell Biology Rat RT2 Profiler PCR Array. RESULTS: the anti-apoptotic Bcl2L1 gene expression was significantly down-regulated (-1.10) in the IRG and significantly up-regulated in the IRG+At (+14.15). Meanwhile, despite Casp1 gene expression was upregulated in both groups, it was significantly higher in the IRG (+35.06) than the IRG+At (+6.68). CONCLUSIONS: Atenolol presents antiapoptotic effects on rat intestine subjected to IR partly by the up-regulation of the anti-apoptotic Bcl2L1 gene expression. Moreover, atenolol can mitigate the pro-apoptotic and pro-inflammatory effects of Casp1 gene on rat intestine after IR.

Gonadotropin-Dependent Neuregulin-1 Signaling Regulates Female Rat Ovarian Granulosa Cell Survival.

Mammalian ovarian follicular development and maturation of an oocyte competent to be fertilized and develop into an embryo depends on tightly regulated, spatiotemporally orchestrated crosstalk among cell death, survival, and differentiation signals through extra- and intraovarian signals, as well as on a permissive ovarian follicular microenvironment. Neuregulin-1 (NRG1) is a member of the epidermal growth factor-like factor family that mediates its effects by binding to a member of the erythroblastoma (ErbB) family. Our experimental results suggest gonadotropins promote differential expression of NRG1 and erbB receptors in granulosa cells (GCs), and NRG1 in theca cells during follicular development, and promote NRG1 secretions in the follicular fluid (FF) of rat ovaries. During the estrous cycle of rat, NRG1 and erbB receptors are differentially expressed in GCs and correlate positively with serum gonadotropins and steroid hormones. Moreover, in vitro experimental studies suggest that the protein kinase C inhibitor staurosporine (STS) causes the physical destruction of GCs by the activation of caspase-3. Exogenous NRG1 treatment of GCs delayed onset of STS-induced apoptosis and inhibited cleaved caspase-3 expressions. Moreover, exogenous NRG1 treatment of GCs alters STS-induced death by maintaining the expression of ErbB2, ErbB3, pAkt, Bcl2, and BclxL proteins. Taken together, these studies demonstrate that NRG1 is gonadotropin dependent, differentially regulated in GCs and theca cells, and secreted in ovarian FF as an intracellular survival factor that may govern follicular maturation.

Targeting the differential addiction to anti-apoptotic BCL-2 family for cancer therapy.

BCL-2 family proteins are central regulators of mitochondrial apoptosis and validated anti-cancer targets. Using small cell lung cancer (SCLC) as a model, we demonstrated the presence of differential addiction of cancer cells to anti-apoptotic BCL-2, BCL-XL or MCL-1, which correlated with the respective protein expression ratio. ABT-263 (navitoclax), a BCL-2/BCL-XL inhibitor, prevented BCL-XL from sequestering activator BH3-only molecules (BH3s) and BAX but not BAK. Consequently, ABT-263 failed to kill BCL-XL-addicted cells with low activator BH3s and BCL-XL overabundance conferred resistance to ABT-263. High-throughput screening identified anthracyclines including doxorubicin and CDK9 inhibitors including dinaciclib that synergized with ABT-263 through downregulation of MCL-1. As doxorubicin and dinaciclib also reduced BCL-XL, the combinations of BCL-2 inhibitor ABT-199 (venetoclax) with doxorubicin or dinaciclib provided effective therapeutic strategies for SCLC. Altogether, our study highlights the need for mechanism-guided targeting of anti-apoptotic BCL-2 proteins to effectively activate the mitochondrial cell death programme to kill cancer cells.

Sevoflurane Preconditioning Confers Neuroprotection via Anti-apoptosis Effects.

Neuroprotection against cerebral ischemia afforded by volatile anesthetic preconditioning (APC) has been demonstrated both in vivo and in vitro, yet the underlying mechanism is poorly understood. We previously reported that repeated sevoflurane APC reduced infarct size in rats after focal ischemia. In this study, we investigated whether inhibition of apoptotic signaling cascades contributes to sevoflurane APC-induced neuroprotection. Male Sprague-Dawley rats were exposed to ambient air or 2.4 % sevoflurane for 30 min per day for 4 consecutive days and then subjected to occlusion of the middle cerebral artery (MCAO) for 60 min at 24 h after the last sevoflurane intervention. APC with sevoflurane markedly decreased apoptotic cell death in rat brains, which was accompanied by decreased caspase-3 cleavage and cytochrome c release. The apoptotic suppression was associated with increased ratios of anti-apoptotic Bcl-2 family proteins over pro-apoptotic proteins and with decreased activation of JNK and p53 pathways. Thus, our data suggest that suppression of apoptotic cell death contributes to the neuroprotection against ischemic brain injury conferred by sevoflurane preconditioning.

DHT inhibits the Aß25-35-induced apoptosis by regulation of seladin-1, survivin, XIAP, bax, and bcl-xl expression through a rapid PI3-K/Akt signaling in C6 glial cell lines.

Previous evidences indicate that androgen is neuroprotective in the brain. However, the underling mechanisms remain to be fully elucidated. Moreover, it is controversial whether dihydrotestosterone (DHT) modulates the expression of apoptosis-related effectors, such as survivin, XIAP, bax, and bcl-xl proteins mediated by the PI3-K/Akt pathway, which contributes to androgen neuroprotection. In this study using a C6 glial cell model, apoptotic cells were detected by flow cytometry. Akt, seladin-1, survivin, XIAP, bcl-xl, and bax protein expression is investigated by Western blot. After amyloid ß-protein fragment (Aß25-35) treatment, apoptotic cells at early (annexin V+, PI-) and late (annexin V+, PI+) stages were significantly increased. Apoptosis at early and late was obviously inhibited in the presence of DHT. The effect of DHT was markedly blocked by PI3-K inhibitor LY294002.To elicit the mechanism of DHT protection, the expression of seladin-1, survivin, XIAP, bax, and bcl-xl protein was determined in C6 cells treated with Aß25-35, DHT, or LY294002. Aß25-35 significantly downregulated the expression of seladin-1, survivin, XIAP, bcl-xl protein and upregulated the expression of bax protein. DHT significantly inhibited the expression of bax, seladin-1, survivin, XIAP, and bcl-xl protein induced by Aß25-35. Further, we found the effect of DHT was significantly inhibited by LY294002. Collectively, in a C6 glial cell model, we firstly found that DHT inhibits Aß25-35-induced apoptosis by a rapid nongenic PI-3K/Akt activation as well as regulation of seladin-1, survivin, XIAP, bcl-xl, and bax proteins.

Effect of HGF on the apoptosis of rat corpus cavernosum smooth muscle cells induced by TGFß1.

Corpus cavernosum smooth muscle cells (CCSMCs) are important functional cells for penile erection. We evaluated the effect of transforming growth factor ß1 (TGFß1) and hepatocyte growth factor (HGF) on the viability and apoptosis of CCSMCs in vitro. CCSMCs from healthy male Sprague Dawley rats were randomly divided into four groups: a negative control group, a TGFß1 group, a HGF group and a HGF+ TGFß1 group. Differences in cell viability and apoptosis among groups were observed by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay and flow cytometry. Western blot was used to detect the change of apoptosis-related proteins. The level of reactive oxygen species (ROS) was detected by colorimetry. In the TGFß1 group, the MTT values were obviously decreased at 12 h, 24 h, 48 h-0.320, 0.383 and 0.432 respectively. However, compared with the normal group, the apoptosis index was markedly increased, reaching 26.86% at the 48-h time point. After TGFß1 treatment, the levels of cleaved caspase-3 and p-Smad2 were increased in the cells, but the levels of Bcl-xL, Bcl-2 and p-Akt were significantly lower. However, HGF co-treatment partially reversed these changes and could decrease the intracellular ROS level while increasing the Akt phosphorylation level. These results indicate that TGFß1 might induce apoptosis of CCSMCs in vitro and that HGF could interfere with the above process through downregulation of apoptosis signalling and oxidative stress reaction.