Procyanidins Alleviated Cerebral Ischemia/Reperfusion Injury by Inhibiting Ferroptosis via the Nrf2/HO-1 Signaling Pathway.

Procyanidins (PCs), which are organic antioxidants, suppress oxidative stress, exhibit anti-apoptotic properties, and chelate metal ions. The potential defense mechanism of PCs against cerebral ischemia/reperfusion injury (CIRI) was investigated in this study. Pre-administration for 7 days of a PC enhanced nerve function and decreased cerebellar infarct volume in a mouse middle cerebral artery embolization paradigm. In addition, mitochondrial ferroptosis was enhanced, exhibited by mitochondrial shrinkage and roundness, increased membrane density, and reduced or absent ridges. The level of Fe2+ and lipid peroxidation that cause ferroptosis was significantly reduced by PC administration. According to the Western blot findings, PCs altered the expression of proteins associated with ferroptosis, promoting the expression of GPX4 and SLC7A11 while reducing the expression of TFR1, hence inhibiting ferroptosis. Moreover, the treatment of PCs markedly elevated the expression of HO-1 and Nuclear-Nrf2. The PCs' ability to prevent ferroptosis due to CIRI was decreased by the Nrf2 inhibitor ML385. Our findings showed that the protective effect of PCs may be achieved via activation of the Nrf2/HO-1 pathway and inhibiting ferroptosis. This study provides a new perspective on the treatment of CIRI with PCs.

Activation of Src mediates acquired cisplatin resistance in human lung carcinoma cells.

Cisplatin (CDDP) is the most effective chemotherapeutic drug against lung carcinoma. However, the emergence of resistant clones has severely limited its clinical application. We found that the cisplatin-resistant lung carcinoma cell line A549/CDDP had increased levels of the phosphorylated gap junction protein Cx43 and SRC tyrosine kinase, and low levels of total Cx43 protein and reduced gap junction formation. The SRC kinase inhibitor PP2 increased the expression of total Cx43 protein and enhanced cisplatin sensitivity, indicating that activated SRC kinase induces chemoresistance by decrease total Cx43 level. Furthermore, Cx43 gene silencing in the drug-resistant cell lines abrogated the sensitizing effect of PP2. Taken together, targeting SRC kinase by PP2 reverses cisplatin resistance by upregulating Cx43 protein levels, indicating a novel pathway of cisplatin resistance that may be amenable to therapeutic intervention.

[Expressions of pannexin proteins in I-10 Leydig tumor cells and TM3 Leydig cells and their regulatory effect on the channel function in mice].

OBJECTIVE: To investigate the expressions of the pannexin (Panx) proteins in I-10 Leydig tumor cells and TM3 Leydig cells and their regulatory effect on the Panx channel function in mice. METHODS: The expressions of the Panx-1 and Panx-2 proteins in the mouse Leydig tumor cells were determined by Western blot. The I-10 Leydig tumor cells were treated with carbenoxolone (CBX) at 100 µmol/L or probenecid (PBN) at 200 µmol/L, the fluorescence resonance energy transfer (FRET) detected by time-lapse fluorescence imaging, and the extracellular adenosine 5'-triphosphate (eATP) level measured with the commercial detection kit. Molecular biological methods were used to interfere with shRNA and overexpress mPanx-1 the Panx-1 gene and regulate the expression and function of the Panx-1 protein. RESULTS: The expressions of Panx-1 (ï¼»289.5 ± 55.8ï¼½%) and Panx-2 (ï¼»264.5 ± 24.6ï¼½%) were significantly increased in the I-10 Leydig tumor cells as compared with those in the normal TM3 Leydig cells (both P < 0.05). FRET was remarkably reduced after treated with CBX (ï¼»87.5 ± 17.7ï¼½%) and PBN (ï¼»89.3 ± 14.3ï¼½%) in comparison with that in the control group (both P < 0.01). At 8, 16 and 24 hours, the eATP level was decreased by (57.3 ± 7.2)%, (56.4 ± 9.6)% and (63.4 ± 6.4)% in the CBX group (P < 0.01) and (61.7 ± 2.5)%, (35.8 ± 1.6)% and (13.5 ± 8.3)% in the PBN group (P < 0.01). Molecular biological treatment down-regulated the expression of Panx-1 by (38.3 ± 5.2)% and (31.8 ± 5.1)% in the shRNA1 and shRNA2 groups, respectively (both P < 0.01), but up-regulated that of Panx-1 by (128.4 ± 7.5)% in the mPanx-1 group (P < 0.01) as compared with the negative control. FRET was reduced by (72.4 ± 39.4)% in the shRNA group (P < 0.01) and the eATP level by (14.7 ± 0.1)%, (13.7 ± 0.3)% and (13.1 ± 0.3)% at 8, 16 and 24 hours, respectively (P < 0.01) while FRET elevated by (122.5 ± 17.1)% in the mPanx-1 group (P < 0.01) and the eATP level by (886.1 ± 82.1)%, (885.8 ± 83.3)% and (841.5 ± 21.8)% at 8, 16 and 24 hours, respectively (P < 0.01). CONCLUSIONS: The expressions of Panx-1 and Panx-2 are increased in I-10 mouse Leydig tumor cells, and inhibiting the Panx channel with CBX, PBN and shRNA reduces FRET and the eATP level in the I-10 cells.

[Effect of SRC Kinase on Adriamycin Resistance and Invasion and Metastasis in Human Breast Cancer Cells].

OBJECTIVE: To investigate the role of SRC kinase inhibitor PP2 in drug resistance to adriamycin (ADM) in breast cancer cells and invasion, metastasis of cells. METHODS: MTT assay was used to detect the inhibitory effect of ADM on MCF-7 and MCF-7/ADM cells. The 50% inhibitory concentration (IC50) and resistance index (RI) of cells were calculated. The expression of MDR1, connexin 43 (Cx43) and SRC proteins in breast cancer cells were detected by Western blot assay. Transwell experiment and cell scratch test were used to determine the invasion and migration of cells respectively [MCF-7, MCF-7/ADM, PP2 (1, 2, 4 µmol/L)]. Standard colony formation assay was used to detect the cytotoxicity effect of 4 µmol/L PP2 pretreatment on ADM. RESULTS: ADM inhibited the proliferation of MCF-7 more than MCF-7/ADM cells (P<0.01). The IC50 of MCF-7/ADM cells was 24.55 µmol/L, the IC50 of MCF-7/ADM cells was 770.57 µmol/L, the RI was 31. Compared with MCF-7 cells, expressions of the multidrug resistance proteins MDR1 and SRC were significantly increased (P<0.01). The invasion and migration ability of the MCF-7/ADM cells was stronger than that of the sensitive cells (P<0.01). When MCF-7/ADM was exposed to SRC inhibitor PP2, the invasion and metastasis ability of cells were inhibited (P<0.01) and the rate of colony formation was decreased, that is, more sensitivity to ADM (P<0.01). CONCLUSION: The resistance of MCF-7 to ADM is accompanied by increased expression of SRC. SRC inhibitor PP2 can reduce the cell resistance, ability of invasion and metastasis.

[Protective effects of P2X7 receptor inhibition in cerebral ischemia/reperfusion injury in rats].

OBJECTIVE: To investigate the protective effects of P2X7 receptor (P2X7R) inhibitor against cerebral ischemia/reperfusion (I/R) injury in rats and the possible mechanisms.
 Methods: The neurological deficit of rats was evaluated by Longa score. The infarct volume was examined by 2, 3, 5-triphenyltetrazolium chloride (TTC) staining. The expression levels of extracellular signal-regulated kinase (ERK), phosphorylation extracellular signal-regulated kinas p-ERK), connexin 43 (Cx43), Bax, Bcl-2 and cleaved caspase-3 were detected by Western blot.
 Results: Compared with sham group, the neurobehavioral score (P<0.05) and cerebral infarct volume (P<0.01) of rats in I/R group was increased. Compared with I/R group, brilliant blue G (BBG, the antagonist of P2X7R) or PD98059 (the inhibitor of EKR kinase) could reduce the neurobehavioral score (P<0.01) and cerebral infarct volume significantly (P<0.05). The neurobehavioral score and cerebral infarct volume was further decreased (P<0.05) when rats were treated with both BBG and PD98059. Compared with I/R group, the expression levels of p-ERK, Cx43, cleaved caspase-3 and the ratio of Bax/Bcl-2 were decreased by BBG or PD98059 pretreatment, and the protective effects were further enhanced when rats were treated with both BBG and PD98059 (P<0.05).
 Conclusion: Inhibition of P2X7R reduces the cerebral I/R injury of rats. ERK inhibition is probably involved in the protective effects of P2X7R inhibitor against cerebral I/R injury, which may be related to the reduction of Cx43 and cleaved caspase-3, and the ratio of Bax/Bcl-2.

[Inhibition of gap junctional intercellular communication protects astrocytes from hypoxia/reoxygenation injury].

OBJECTIVE: To investigate the effects of inhibiting gap junctional intercellular communication on hypoxia/reoxygenation injury in astrocytes. METHODS: Primary cultured cerebral cortical astrocytes of neonate rats were divided into normal control group, hypoxia reoxygenation injury group and 18-α-glycyrrhetinic acid and oleamide (gap junctional intercellular channel inhibitors) group. The gap junction intercellular communication was determined by Parachute assay. The viability of astrocyes was detected by MTT assay. The apoptosis of astrocytes were detected with annexin V/PI and Hoechst 33258 staining. RESULTS: Compared with the normal control group, the gap junctional function of astrocytes was increased significantly in ischemia/reperfusion group (P<0.01), the surviving fraction of astrocytes decreased significantly (P<0.01) and its cell apoptosis ratio increased significantly (P<0.01). Compared with the ischemia/reperfusion group, the gap junctional function of astrocytes in18-α-glycyrrhetinic acid and oleamide group decreased significantly (P<0.01), the viability of astrocytes increased significantly (P<0.01), while cell apoptosis decreased significantly (P<0.01). CONCLUSION: Inhibition of intercellular gap junction has protective effect against hypoxia/reoxygenation injury in astrocytes.

[Baicalein enhances the gap junction in the TM4 Sertoli cells of mice].

OBJECTIVE: To investigate the effect of baicalein on the gap junction intercellular communication (GJIC) in the TM4 Sertoli cells of the mouse testis and its related mechanism. METHODS: We measured the cytotoxicity of different concentrations of baicalein on the TM4 Sertoli cells in the mouse testis by MTT, detected the fluorescence transfer of the TM4 Sertoli cells by parachute assay, and determined the expression of the protein connexin 43 ( Cx43) in the baicalein-treated cells by Western blot and immunofluorescence assay. RESULTS: Baicalein produced no obvious cytotoxicity on the TM4 Sertoli cells at the concentration below 60 µmol/L but significantly increased their GJIC at 0-20 µmol/L (P < 0.01). Western blot and immunofluorescence assay showed that 0-20 µmol/L baicalein remarkably elevated the expression of Cx43 in the TM4 cells (P < 0.01) and on the membrane of the TM4 cells. CONCLUSION: Baicalein at the concentration of 0-20 µmol/L can significantly enhance GJIC in mouse TM4 Sertoli cells by increasing the expression of the Cx43 protein.

[Gefitineb inhibits the growth and induces the apoptosis of mouse I-10 Leydig testicular cancer cells in vitro].

OBJECTIVE: To observe the inhibitory effect of gefitineb on the proliferation and its inducing effect on the apoptosis of mouse I-10 Leydig testicular cancer cells in vitro. METHODS: We treated I-10 Leydig testicular cancer cells of mice with gefitineb at 0, 1.25, 2.5, 5, 10, 20, and 40 µmol/L. Then we determined the inhibitory effect of gefitineb on the growth of the cells by MTT, detected their early and late apoptosis by Annexin V-FITC/propidium iodide double staining and Hoechst 33258 nuclear staining, respectively, and observed the expressions of apoptosis-related proteins Bcl-2, Bax and caspase 3/9 by Western blot. RESULTS: Compared with the blank control group, gefitineb significantly inhibited the proliferation of the I-10 cells at 10 and 20 µmol/L (P < 0.05). The survival rate of the cells was (32.4 ± 2.8)% (P < 0.01) and their early and late apoptosis rates were (26.7 ± 4.2)% and (59.33 ± 10.2)% in the 40 µmol/L group, significantly different from those in the control (P < 0.05 and P <0.01). In comparison with the blank control group, gefitineb at 10, 20, and 40 µmol/L increased the expression of pro-apoptotic protein Bax by (41.9 ± 7.1), (60.1 ± 9.8), and (69.0 ± 11.3)% (all P < 0.05), decreased that of apoptosis-inhibitory protein Bcl-2 by (50.3 ± 8.9), (63.9 ± 6.9), and (88.7 ± 13.9)% (all P < 0.05), and elevated that of the cleft proteins caspase-3 by (69.0 ± 6.9)% (P < 0.05), (71.5 ± 8.1)% (P < 0.05), and (110.9 ± 14.2)% (P < 0.01) and caspase-9 by (51.8 ± 4.9), (54.7 ± 6.7), and (43.8 ± 11.8)% (all P < 0.05). CONCLUSION: Gefitineb can increase the cytotoxicity of I-10 Leydig testicular cancer cells of mice and induce their apoptosis via the mitochondria-mediated apoptosis signaling pathway.

Total flavonoids of litsea coreana enhance the cytotoxicity of oxaliplatin by increasing gap junction intercellular communication.

Oxaliplatin is widely used in the treatment of variety of cancers, including cancer of the testis and colorectum. Gap junctions (GJs) can amplify the cytotoxicity of antinoeoplastic drugs through the bystander effect in different cancer cells. In this study, we demonstrate that total flavonoids of litsea coreana (TFLC), one extract from the dried leaves of litsea coreana leve, increase the cytotoxicity of oxaliplatin in mouse testicular cancer I-10 cells. We found that cell survival was substantially decreased only when functional GJs formed in I-10 cells. TFLC increased oxaliplatin cytotoxity (inducing cell death and apoptosis) by enhancing gap junction intercellular communication (GJIC) through elevated Cx43 protein expression. Furthermore, apoptosis-related protein (Bax, Bcl-2, caspase-3/9) results showed that the Bax/Bcl-2 ratio and activated caspase-3/9 increased when TFLC was used compared with treatment with oxaliplatin alone, which suggests that the mechanism of increased oxaliplatin-induced apoptosis was through the mitochondrial pathway. These results demonstrate that TFLC can enhance the cytotoxicity of oxaliplatin, and that these processes may be regulated in testicular tumor cells through GJ-mediated regulation of tumor cell apoptosis.

[Total flavonoids of litsea coreana decreases the cytotoxicity of oxaliplatin in TM3 Leydig cells via enhancing the function of gap junction].

OBJECTIVE: To investigate the effects of total flavonoids of Litsea Coreana (TFLC) on the gap junction (GJ) intercellular communication in TM3 testicular Leydig cells and whether TFLC can reduce the cytotoxicity of oxaliplatin (OHP) in vitro. METHODS: We detected the effect of TFLC on the dye spread of the in vitro cultured TM3 cells by parachute assay, observed changes in the expression of connexin 43 (Cx43) total protein in the TFLC-treated TM3 cells by Western blot, and determined the effects of TFLC on the expression of Cx43 on the membrane of the TM3 cells by immunofluorescence assay and on the cytotoxicity of OHP by MTT assay. RESULTS: TFLC obviously enhanced the GJ function with the increasing of the TFLC concentration in the TM3 cells. Western blot and immunofluorescence assay confirmed that TFLC significantly enhanced the expression of Cx43 total protein and Cx43 expression on the membrane of the TM3 cells. MTT assay showed that at a high cell density (confluent with GJ formation), 20 microg/ml TFLC enhanced the GJ function of the TM3 cells and reduced the cytotoxicity of OHP (P < 0.05), while at a low density (preconfluent with no GJ formation), TFLC exhibited no effect on the cytotoxicity of OHP (P > 0.05). CONCLUSION: TFLC increases the Cx43 expression and GJ function in normal TM3 Leydig cells, and the enhancement of GJ function reduces the cytotoxicity of OHP.

[PP2 enhances intercellular communication of gap junction in breast cancer Hs578T cells].

OBJECTIVE: To investigate the effect of Src kinase inhibitor PP2 on intercellular communication of gap junction in breast cancer cells. METHODS: Cultured breast cancer Hs578T cells were treated with various concentrations of pp2 (0,1,2,4,8,16,32 µmol/L) for 24h. Cell growth was determined by MTT assay; dye spread in Hs578T cells was measured by Parachute assay; and the expression of Src kinase in Hs578T cells was detected by Western blot. RESULTS: MTT assay showed that the survive rate of Hs578T cells treated with PP2 (1 ≊ 8 µmol/L) was 98% ± 3% ≊ 94 % ± 4%. Parachute assay showed that compared to control group the standard normalized dye spread rates of Hs578T cells treated with 1,2,4 and 8 µmol/L PP2 were 1.60 ± 0.08,2.00 ± 0.05,2.20 ± 0.05 and 2.70 ± 0.09,respectively (all P<0.01). Moreover,compared to control group at the same time points,the standard normalized dye spread of Hs578T cells treated with 8 µmol/L PP2 for 6,12 and 24 h were 1.4 ± 0.05,1.7 ± 0.06,and 2.2 ± 0.07,respectively (all P<0.01). Western blot showed that the expression ratios of Src kinase/ß-actin of Hs578T cells treated with 1,2,4 and 8 µmol/L PP2 for 24 h were 0.93 ± 0.02,0.70 ± 0.09,0.66 ± 0.09 and 0.36 ± 0.10,which were significantly inhibited compared with control group (P<0.05 or 0.01). And the expression ratio of Src kinase/ß-actin of Hs578T cells treated with 8 µmol/L PP2 for 6,12 and 24h was 0.82 ± 0.03,0.66 ± 0.08 and 0.59 ±0.09, which were all inhibited significantly compared to control group (P<0.01). CONCLUSION: PP2 enhances the gap junction function in breast cancer Hs578T cells, which is probably related to the inhibition of Src kinase.

[Effects of retinoic acid on the expression of Cx43 and its gap juncion intercellular communication function in testicular cancer cell].

OBJECTIVE: To investigate the effects of retinoic acid (RA) on the expression of Cx43 and its gap junction intercellular communication function in testicular cancer cells. METHODS: Cultured testicular cancer cells I-10 were treated with different concentration of RA (2.5, 5.0,10.0 micromol/L). The expression of Cx43 in 1-10 cells was detected by Western blot, and the distribution and location of Cx43 on cellular membrane was studied with immunofluorescence assay. Parachute assay was used to detect the function of gap junction intercellular communication composed of Cx43 in 1-10 cells. RESULTS: RA (2.5, 5.0, 10.0 micromol/L) markedly increased the expression of Cx43 in I-10 cells, the enhancement ratios were 43.14% +/- 2.1%, 58.09% +/- 1.8%, 143.13% +/- 1.6%, respectively. The result of immunofluorescence assay showed that RA (2.5, 5.0, 10.0 micromol/L) obviously increased the level of Cx43 located on the cellular membrane of I-10 cells. The result of parachute assay demonstrated that RA (2.5,5.0,10.0 gmol/L) could enhance the intercellular dye coupling through gap junction, the enhancement ratios were 26.1% +/- 2.3%, 63.3% +/- 1.6%, 140.5% +/- 3.4%, respectively. CONCLUSION: RA could enhance the gap junction intercellular communication by increasing the expression of Cx43 in I-10 cells.

The role of mitochondrial dynamics in cerebral ischemia-reperfusion injury.

Stroke is one of the leading causes of death and long-term disability worldwide. More than 80 % of strokes are ischemic, caused by an occlusion of cerebral arteries. Without question, restoration of blood supply as soon as possible is the first therapeutic strategy. Nonetheless paradoxically, reperfusion can further aggravate the injury through a series of reactions known as cerebral ischemia-reperfusion injury (CIRI). Mitochondria play a vital role in promoting nerve survival and neurological function recovery and mitochondrial dysfunction is considered one of the characteristics of CIRI. Neurons often die due to oxidative stress and an imbalance in energy metabolism following CIRI, and there is a strong association with mitochondrial dysfunction. Altered mitochondrial dynamics is the first reaction of mitochondrial stress. Mitochondrial dynamics refers to the maintenance of the integrity, distribution, and size of mitochondria as well as their ability to resist external stimuli through a continuous cycle of mitochondrial fission and fusion. Therefore, improving mitochondrial dynamics is a vital means of treating CIRI. This review discusses the relationship between mitochondria and CIRI and emphasizes improving mitochondrial dynamics as a potential therapeutic approach to improve the prognosis of CIRI.

Ferroptosis is involved in polymyxin B-induced acute kidney injury via activation of p53.

Polymyxin B (PMB) is one of the most effective drugs for the treatment of multi-resistant and pan-resistant gram-negative infections. However, it can induce acute kidney injury (AKI), the mechanism of which has not yet been fully elucidated. In this study, RNA sequencing and in vitro and in vivo experiments demonstrated that PMB induced AKI by promoting ferroptosis. Moreover, the metallothionein-1 (MT-1) level was significantly increased in the AKI group and clinical cases revealed that iron and MT-1 levels in urine were significantly higher in patients with AKI than in those without AKI. To explore the mechanism of PMB induced ferroptosis, we silenced p53 in human kidney-2 (HK2) cells according to RNA sequencing, which showed that p53 was obviously enhanced in the PMB treated group. While PMB significantly enhanced Fe2+, lipid peroxidation, malondialdehyde (MDA), transferrin receptor protein 1 (TFR1), and arachidonate 12-lpoxygenase (ALOX12), decreased the survival rate, solute carrier family 7 member 11 (SLC7A11), glutathione peroxidase 4 (GPX4), and glutathione (GSH), downregulation of p53 reversed these effects, suggesting PMB induced ferroptosis by activating p53. Studies have shown p53 can promote ferroptosis by regulating the downstream factors SLC7A11 or TFR1. Further, we verified that silencing TFR1 expression as well as overexpression of SLC7A11 inhibited ferroptosis and significantly increased the survival rate of HK2 cells. Overall, PMB induces ferroptosis in renal tubular cells by activating p53 to reduce SLC7A11 expression and elevate TFR1, leading to AKI; MT-1 and iron levels in urine were significantly increased when PMB induced ferroptosis.

Upregulation of CDGSH iron sulfur domain 2 attenuates cerebral ischemia/reperfusion injury.

CDGSH iron sulfur domain 2 can inhibit ferroptosis, which has been associated with cerebral ischemia/reperfusion, in individuals with head and neck cancer. Therefore, CDGSH iron sulfur domain 2 may be implicated in cerebral ischemia/reperfusion injury. To validate this hypothesis in the present study, we established mouse models of occlusion of the middle cerebral artery and HT22 cell models of oxygen-glucose deprivation and reoxygenation to mimic cerebral ischemia/reperfusion injury in vivo and in vitro, respectively. We found remarkably decreased CDGSH iron sulfur domain 2 expression in the mouse brain tissue and HT22 cells. When we used adeno-associated virus and plasmid to up-regulate CDGSH iron sulfur domain 2 expression in the brain tissue and HT22 cell models separately, mouse neurological dysfunction was greatly improved; the cerebral infarct volume was reduced; the survival rate of HT22 cells was increased; HT22 cell injury was alleviated; the expression of ferroptosis-related glutathione peroxidase 4, cystine-glutamate antiporter, and glutathione was increased; the levels of malondialdehyde, iron ions, and the expression of transferrin receptor 1 were decreased; and the expression of nuclear-factor E2-related factor 2/heme oxygenase 1 was increased. Inhibition of CDGSH iron sulfur domain 2 upregulation via the nuclear-factor E2-related factor 2 inhibitor ML385 in oxygen-glucose deprived and reoxygenated HT22 cells blocked the neuroprotective effects of CDGSH iron sulfur domain 2 up-regulation and the activation of the nuclear-factor E2-related factor 2/heme oxygenase 1 pathway. Our data indicate that the up-regulation of CDGSH iron sulfur domain 2 can attenuate cerebral ischemia/reperfusion injury, thus providing theoretical support from the perspectives of cytology and experimental zoology for the use of this protein as a therapeutic target in patients with cerebral ischemia/reperfusion injury.

Panax notoginseng saponins enhances the cytotoxicity of cisplatin via increasing gap junction intercellular communication.

Panax Notoginseng Saponins (PNS) have been well known to have anti-tumor activity and enhance cytotoxicity of some cancer chemotherapy agents, but the mechanisms underlying these effects are still unknown. This study investigates the effect of PNS on cytotoxicity of cisplatin and the relationship between this effect and the modulation of gap junctions (GJ) function by PNS in a transfected cell line. The cytotoxicity of cisplatin (0.25-1 µg/mL) was increased in the presence of GJ. Inhibition of gap junction by either GJ blocker or interception of Connexin (Cx) expression decreased the cytotoxicity of cisplatin. Increasing GJ function enhanced cytotoxicity of cisplatin, only in the cells with functional GJ. PNS (50-200 µg/mL) significantly enhanced cisplatin cytotoxicity, but this effect required functional gap junctions between the cells. Exposure of the cells to PNS (50-200 µg/mL) for 4 h leads to a significant enhance in dye coupling of GJ in a dose-dependent manner. These results suggest that PNS increases the cytotoxicity of cisplatin through enhancement of GJ activity.

Pannexin1 inhibits autophagy of cisplatin-resistant testicular cancer cells by mediating ATP release.

Pannexin1 (Panx-1) is a gap junction channel protein that mediates the release of intracellular ATP during autophagy, and thus plays an important role in tumor cell apoptosis and chemo-resistance. However, the role of Panx-1 in cisplatin-resistance of testicular cancer cells remains unclear. We found that cisplatin-resistant I-10 testicular cancer cell lines (I-10/CDDP) autophagy-associated proteins (p62, p-mTOR, mTOR and LC3) exhibited high levels of autophagy in their expression, while LC3-II expression was more significantly in the presence of lysosomal degradation blocked by chloroquine (CQ). Xenograft models using I-10/CDDP cells with knockdown ATG5 and ATG7 were established in mouse models and showed blockade of autophagic flux and inhibition of tumor growth. In addition, inhibition of Panx-1 by carbenoxolone (CBX) and probenecid (PBN), as well as shRNA-mediated knockdown promoted autophagy in the I-10/CDDP cells, which was accompanied by a decrease in the levels of extracellular ATP. In contrast, overexpression of Panx-1 decreased autophagy of I-10/CDDP cells and increased extracellular ATP levels. To further determine the effect of panx-1-mediated ATP release on the autophagy of I-10/CDDP cells, apyrase was used to hydrolyze the extracellular ATP. Apyrase promoted autophagy in I-10/CDDP cells city by decreasing extracellular ATP, regardless of Panx-1 expression. This study demonstrated for the first time that Panx-1-mediated ATP release inhibits autophagy of I-10/CDDP cells, which provides a potential therapeutic strategy for cisplatin-resistant testicular cancer.

Liquid-liquid phase separation in tumor biology.

Liquid-liquid phase separation (LLPS) is a novel principle for explaining the precise spatial and temporal regulation in living cells. LLPS compartmentalizes proteins and nucleic acids into micron-scale, liquid-like, membraneless bodies with specific functions, which were recently termed biomolecular condensates. Biomolecular condensates are executors underlying the intracellular spatiotemporal coordination of various biological activities, including chromatin organization, genomic stability, DNA damage response and repair, transcription, and signal transduction. Dysregulation of these cellular processes is a key event in the initiation and/or evolution of cancer, and emerging evidence has linked the formation and regulation of LLPS to malignant transformations in tumor biology. In this review, we comprehensively summarize the detailed mechanisms of biomolecular condensate formation and biophysical function and review the recent major advances toward elucidating the multiple mechanisms involved in cancer cell pathology driven by aberrant LLPS. In addition, we discuss the therapeutic perspectives of LLPS in cancer research and the most recently developed drug candidates targeting LLPS modulation that can be used to combat tumorigenesis.

Targeting cell death pathways for cancer therapy: recent developments in necroptosis, pyroptosis, ferroptosis, and cuproptosis research.

Many types of human cells self-destruct to maintain biological homeostasis and defend the body against pathogenic substances. This process, called regulated cell death (RCD), is important for various biological activities, including the clearance of aberrant cells. Thus, RCD pathways represented by apoptosis have increased in importance as a target for the development of cancer medications in recent years. However, because tumor cells show avoidance to apoptosis, which causes treatment resistance and recurrence, numerous studies have been devoted to alternative cancer cell mortality processes, namely necroptosis, pyroptosis, ferroptosis, and cuproptosis; these RCD modalities have been extensively studied and shown to be crucial to cancer therapy effectiveness. Furthermore, evidence suggests that tumor cells undergoing regulated death may alter the immunogenicity of the tumor microenvironment (TME) to some extent, rendering it more suitable for inhibiting cancer progression and metastasis. In addition, other types of cells and components in the TME undergo the abovementioned forms of death and induce immune attacks on tumor cells, resulting in enhanced antitumor responses. Hence, this review discusses the molecular processes and features of necroptosis, pyroptosis, ferroptosis, and cuproptosis and the effects of these novel RCD modalities on tumor cell proliferation and cancer metastasis. Importantly, it introduces the complex effects of novel forms of tumor cell death on the TME and the regulated death of other cells in the TME that affect tumor biology. It also summarizes the potential agents and nanoparticles that induce or inhibit novel RCD pathways and their therapeutic effects on cancer based on evidence from in vivo and in vitro studies and reports clinical trials in which RCD inducers have been evaluated as treatments for cancer patients. Lastly, we also summarized the impact of modulating the RCD processes on cancer drug resistance and the advantages of adding RCD modulators to cancer treatment over conventional treatments.

Soluble ligands as drug targets for treatment of inflammatory bowel disease.

Inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis, is characterized by persistent inflammation in a hereditarily susceptible host. In addition to gastrointestinal symptoms, patients with IBD frequently suffer from extra-intestinal complications such as fibrosis, stenosis or cancer. Mounting evidence supports the targeting of cytokines for effective treatment of IBD. Cytokines can be included in a newly proposed classification "soluble ligands" that has become the third major target of human protein therapeutic drugs after enzymes and receptors. Soluble ligands have potential significance for research and development of anti-IBD drugs. Compared with traditional drug targets for IBD treatment, such as receptors, at least three factors contribute to the increasing importance of soluble ligands as drug targets. Firstly, cytokines are the main soluble ligands and targeting of them has demonstrated efficacy in patients with IBD. Secondly, soluble ligands are more accessible than receptors, which are embedded in the cell membrane and have complex tertiary membrane structures. Lastly, certain potential target proteins that are present in membrane-bound forms can become soluble following cleavage, providing further opportunities for intervention in the treatment of IBD. In this review, 49 drugs targeting 25 distinct ligands have been evaluated, including consideration of the characteristics of the ligands and drugs in respect of IBD treatment. In addition to approved drugs targeting soluble ligands, we have also assessed drugs that are in preclinical research and drugs inhibiting ligand-receptor binding. Some new types of targetable soluble ligands/proteins, such as epoxide hydrolase and p-selectin glycoprotein ligand-1, are also introduced. Targeting soluble ligands not only opens a new field of anti-IBD drug development, but the circulating soluble ligands also provide diagnostic insights for early prediction of treatment response. In conclusion, soluble ligands serve as the third-largest protein target class in medicine, with much potential for the drugs targeting them.