Targeting the p38 MAPK pathway inhibits irinotecan resistance in colon adenocarcinoma

Despite recent advances in the treatment of colon cancer, tumor resistance is a frequent cause of chemotherapy failure. To better elucidate the molecular mechanisms involved in resistance to irinotecan (and its active metabolite SN38), we established SN38-resistant clones derived from HCT-116 and SW48 cell lines. These clones show various levels (6- to 60-fold) of resistance to SN-38 and display enhanced levels of activated MAPK p38 as compared with the corresponding parental cells. Because four different isoforms of p38 have been described, we then studied the effect of p38 overexpression or downregulation of each isoform on cell sensivity to SN38 and found that both α and β isoforms are involved in the development of resistance to SN38. In this line, we show that cell treatment with SB202190, which inhibits p38α and p38β, enhanced the cytotoxic activity of SN38. Moreover, p38 inhibition sensitized tumor cells derived from both SN38-sensitive and -resistant HCT116 cells to irinotecan treatment in xenograft models. Finally, we detected less phosphorylated p38 in primary colon cancer of patients sensitive to irinotecan-based treatment, compared with nonresponder patients. This indicates that enhanced level of phosphorylated p38 could predict the absence of clinical response to irinotecan. Altogether, our results show that the p38 MAPK pathway is involved in irinotecan sensitivity and suggest that phosphorylated p38 expression level could be used as a marker of clinical resistance to irinotecan. They further suggest that targeting the p38 pathway may be a potential strategy to overcome resistance to irinotecan-based chemotherapies in colorectal cancer.     

乳腺癌细胞耐药过程中p38MAPK活性与细胞凋亡的关系

目的研究乳腺癌细胞耐药过程中p38MAPK活性与细胞凋亡的关系,探讨p38MAPK信号转导途径在其中的作用。方法 以p38MAPK特异性抑制剂SB203580处理乳腺癌耐药细胞MCF-7／ADM,采用流式细胞技术分析对细胞凋亡的影响;MTT检测MCF-7／ADM细胞对阿霉素的半数药物抑制浓度（IC50）;Western blot检测SB203580处理MCF-7／ADM和MCF-7两株细胞后p38MAPK蛋白表达水平;RT—PCR检测细胞内MDR-1 mRNA水平。结果SB203580（10μmol／L）干预24h后MCF-7／ADM细胞的凋亡率为（26．73±4．90）％,与未干预组和对照组凋亡率相比差异有显著统计学意义（F=143．80,P〈0．001）;MCF-7／ADM细胞对阿霉素的敏感性明显提高（F=148927．10,P〈0．001）,相对逆转率达68．45％;与对照组和未干预组相比,干预组的MDR1 mRNA（F=9139．24,P〈0．001）及p38MAPK（F=685．42,P〈0．001）蛋白表达水平明显降低。结论p38MAPK信号转导途径与乳腺癌耐药密切相关,其可能机制为p38MAPK保护人乳腺癌耐药细胞（MCF-7／ADM）逃避凋亡,阻断该通路可增强乳腺癌耐药细胞发生凋亡。     

乳腺癌细胞药耐中P38MAPK活性与凋亡关系的实验研究

Objective  

The aim of this study was to investigate the relationship between p38MAPK activity and apoptosis during the drug resistance of breast carcinoma cell lines.     

AQP5 silencing suppresses p38 MAPK signaling and improves drug resistance in colon cancer cells

It is known that aquaporin 5 (AQP5) may represent a novel therapeutic target for treating colon cancer (CC), but whether AQP5 plays a role in the regulation of multidrug resistance (MDR) of colon cancer still remains unclear. In the present study, AQP5 and P-glycoprotein (P-gp), glutathione S-transferase-π (GST-π), topoisomerase II (TOPO II), and thymidylate synthase (TS) were checked in CC and adjacent cancer tissues; AQP5-siRNA was applied to silencing AQP5 in CC cell line HT-29, 5-fluorouracil (5-FU), and cisplatin (DDP) added on cells, and sulforhodamine B (SRB) was used; fluorescence real-time quantitative RT-PCR and Western blot were employed to detect changes in multidrug resistance factor and expression mitogen-activated protein kinase (MAPK) signaling pathway in HT-29. The results showed that AQP5 is significantly induced in cancer tissues than that in adjacent cancer tissues. The expression of AQP5 is positively correlated with drug resistance factors, as demonstrated by the increased expressions of P-gp, GST-π, and TOPO II in CC tissues compared to that in adjacent cancer tissues. Conversely, knockdown of AQP5 in HT-29 human colon cancer cells increased inhibition rates of cancer chemotherapeutic drugs such as 5-FU and DDP. The improved efficacies of chemotherapeutic drugs are associated with the decreased expression of P-gp, GST-π, and TOPO II. In addition, phosphorylation of p38 MAPK was increased by knockdown of AQP5 in HT-29 cells while phosphorylation and expression of extracellular signal-regulated kinase (ERK), c-jun N-terminal kinase (JNK), and Protein kinase B (AKT) were not affected. P38 MAPK inhibitor increased the drug sensitivity of HT-29 cells in a similar way as AQP5-siRNAs do. So these results indicate that AQP5 is associated with drug resistance of colon cancer, and that the AQP5-P38 MAPK pathway may represent a potential drug target to improve drug resistance of colon cancer cells.     

Indirubin-3'-monoxime inhibits autophosphorylation of FGFR1 and stimulates ERK1/2 activity via p38 MAPK

Indirubin-3'-monoxime is a derivative of the bis-indole alkaloid indirubin, an active ingredient of a traditional Chinese medical preparation that exhibits anti-inflammatory and anti-leukemic activities. Indirubin-3'-monoxime is mainly recognized as an inhibitor of cyclin-dependent kinases (CDKs) and glycogen synthase kinase-3. It inhibits proliferation of cultured cells, mainly through arresting the cells in the G1/S or G2/M phase of the cell cycle. Here, we report that indirubin-3'-monoxime is able to inhibit proliferation of NIH/3T3 cells by specifically inhibiting autophosphorylation of fibroblast growth factor receptor 1 (FGFR1), blocking in this way the receptor-mediated cell signaling. Indirubin-3'-monoxime inhibits the activity of FGFR1 at a concentration lower than that required for inhibition of phosphorylation of CDK2 and retinoblastoma protein and cell proliferation stimulated by fetal calf serum. The ability of indirubin-3'-monoxime to inhibit FGFR1 signaling was similar to that of the FGFR1 inhibitor SU5402. In addition, we found that indirubin-3'-monoxime activates long-term p38 mitogen-activated protein kinase activity, which stimulates extracellular signal-regulated kinase 1/2 in a way unrelated to the activity of FGFR1. Furthermore, we show that indirubin-3'-monoxime can inhibit proliferation of the myeloid leukemia cell line KG-1a through inhibition of the activity of the FGFR1 tyrosine kinase. The data presented here demonstrate previously unknown activities of indirubin-3'-monoxime that may have clinical implications.     

c-Abl activates p38 MAPK independently of its tyrosine kinase activity: Implications in cisplatin-based therapy

Activation of p38 MAPK is a critical requisite for the therapeutics activity of the antitumor agent cisplatin. In this sense, a growing body of evidences supports the role of c-Abl as a major determinant of p38 MAPK activation, especially in response to genotoxic stress when triggered by cisplatin. Here, we demonstrate that p38 MAPK activation in response to cisplatin does not require the tyrosine kinase activity of c-Abl. Indeed, c-Abl can activate the p38 MAPK signaling pathway by a mechanism that is independent of its tyrosine kinase activity, but that instead involves the ability of c-Abl to increase the stability of MKK6. Similar results were obtained in chronic myeloid leukemia-derived cell lines, in which a chimeric Bcr/Abl protein mimics the effects of c-Abl overexpression on p38 MAPK activation. These findings may explain why a clinically used c-Abl inhibitor, imatinib mesylate, fails to inhibit the p38 MAPK pathway alone or in combination with cisplatin, and provide evidence of a novel signaling mechanism in which these antitumor agents act.     

p38 MAPK在胃泌素诱导结肠癌细胞表达u-PA中的作用

目的研究胃泌素对人结肠癌细胞尿激酶型纤溶酶原激活物(u-PA)mRNA和蛋白表达的影响,探讨信号分子p38 MAPK在其中的作用。方法采用脂质体介导法,将胃泌素受体(CCK_2R)的真核表达载体pCR3.1/CCK_2R稳定转染人结肠癌细胞株colo320,上调胃泌素的作用;用胃泌素拮抗剂(L-365、260)下调胃泌素的作用。给予10nmo/L胃泌素刺激不同时间,阻断实验以SB203580阻断p38通路,采用逆转录-聚合酶链反应(RT-PCR)检测细胞内u-PA mRNA的表达,采用Western blot检测细胞内u-PA和p38 MAPK蛋白表达的强度。结果胃泌素可明显增强colo320/ CCK_2R细胞u-PA mRNA和蛋白的表达,并可激活p38 MAPK蛋白的磷酸化,具有时间依赖性,但对colo320细胞的影响程度明显低于colo320/CCK_2R细胞。使用L-365、260后,胃泌素对u-PA和phospho p38 MAPK的诱导作用明显下降。SB203580可明显抑制胃泌素诱导的p38 MAPK激酶的磷酸化,用其阻断p38激酶信号通路后,胃泌素对u-PA的诱导作用受到显著的抑制,并且具有剂量依赖性。结论胃泌素与其受体结合后,可通过p38 MAPK信号转导通路诱导结肠癌细胞表达u-PA。     

The effects of IL-2, IL-6 and IL-10 levels on prognosis in patients with aggressive Non-Hodgkin's Lymphoma (NHL)

The aim of this study was to investigate serum levels of IL-2, IL-6 and IL-10 in the pretreatment period and to determine if high IL-2, IL-6, IL-10 levels correlate with the outcome in patients with Non-Hodgkin's Lymphoma (NHL) in the post treatment period. Forty-three patients with the diagnosis of aggressive NHL were included in our study. In all cases initial treatment consisted of CHOP. Patients who failed initial therapy and relapsed from CR were treated with the ESHAP regimen or autologous bone marrow transplantation.The median follow-up duration was 127 weeks (20-228 weeks). There was a negative relationship between the failure-free survival and IL-2 levels (p<0.01). IL-2 levels were negatively correlated with overall survival (p<0.02). There was no relationship between the failure-free survival and IL-6 and IL-10 levels. IL-6 and IL-10 levels did not affect overall survival. In conclusion, in patients with lymphoma, the immune system tries to control the progression of tumor thus leading to high IL-2 levels.     

Knockdown of NUPR1 inhibits the proliferation of glioblastoma cells via ERK1/2, p38 MAPK and caspase-3

Nuclear protein-1 (NUPR1), located on chromosome 16p11.2, is a stress response factor that plays an important role in the growth and migration of human malignant tumor cells. However, the role of NUPR1 in glioblastoma remains poorly understood. The expression level of NUPR1 was detected by quantitative real-time PCR and immunohistochemistry (IHC). Wound healing, MTT, cell counting and BrdU assays were used to analyze the migration and proliferation of glioblastoma cells after down-regulating NUPR1 expression using a lentiviral vector. FACS analysis and a signaling antibody array kit were used to detect the mechanism by which NUPR1 modulates cell cycle and apoptosis activities in glioblastoma cells. We confirmed that NUPR1 was up-regulated in glioblastoma tissues compared to NB tissues. Down-regulation of NUPR1 suppressed cell migration and proliferation, arrested the cell cycle in the G0/G1 phase and promoted apoptosis in U251 and U87 cells in vitro. Furthermore, the expression levels of phosphorylated ERK1/2, p38 MAPK and cleaved caspase-3 were decreased upon silencing NUPR1 expression in U251 and U87 cells. In summary, NUPR1 plays an important role in the growth and migration of human glioblastoma cells. Knockdown of NUPR1 suppressed glioblastoma cell growth by arresting the cell cycle and inducing cell apoptosis via decreases in the expression of ERK1/2, p38 MAPK and caspase-3.     

A role for p38 MAPK in head and neck cancer cell growth and tumor-induced angiogenesis and lymphangiogenesis

We have recently gained a remarkable understanding of the mutational landscape of head and neck squamous cell carcinoma (HNSCC). However, the nature of the dysregulated signaling networks contributing to HNSCC progression is still poorly defined. Here, we have focused on the role of the family of mitogen activated kinases (MAPKs), extracellular regulated kinase (ERK), c-Jun terminal kinase (JNK) and p38 MAPK in HNSCC. Immunohistochemical analysis of a large collection of human HNSCC tissues revealed that the levels of the phosphorylated active form of ERK1/2 and JNK were elevated in less than 33% and 16% of the cases, respectively. Strikingly, however, high levels of active phospho-p38 were observed in most (79%) of hundreds of tissues analyzed. We explored the biological role of p38 in HNSCC cell lines using three independent approaches: treatment with a specific p38 inhibitor, SB203580; a retro-inhibition strategy consisting in the use of SB203580 combined with the expression of an inhibitor-insensitive mutant form of p38α; and short-hairpin RNAs (shRNAs) targeting p38α. We found that specific blockade of p38 signaling significantly inhibited the proliferation of HNSCC cells both in vitro and in vivo. Indeed, we observed that p38 inhibition in HNSCC cancer cells reduces cancer growth in tumor xenografts and a remarkable decrease in intratumoral blood and lymphatic vessels. We conclude that p38α functions as a positive regulator of HNSCC in the context of the tumor microenvironment, controlling cancer cell growth as well as tumor-induced angiogenesis and lymphangiogenesis.     

EphB2 activity plays a pivotal role in pediatric medulloblastoma cell adhesion and invasion

Eph/ephrin signaling has been implicated in various types of key cancer-enhancing processes, like migration, proliferation, and angiogenesis. In medulloblastoma, invading tumor cells characteristically lead to early recurrence and a decreased prognosis. Based on kinase-activity profiling data published recently, we hypothesized a key role for the Eph/ephrin signaling system in medulloblastoma invasion. In primary medulloblastoma samples, a significantly higher expression of EphB2 and the ligand ephrin-B1 was observed compared with normal cerebellum. Furthermore, medulloblastoma cell lines showed high expression of EphA2, EphB2, and EphB4. Stimulation of medulloblastoma cells with ephrin-B1 resulted in a marked decrease in in vitro cell adhesion and an increase in the invasion capacity of cells expressing high levels of EphB2. The cell lines that showed an ephrin-B1-induced phenotype possessed increased levels of phosphorylated EphB2 and, to a lesser extent, EphB4 after stimulation. Knockdown of EphB2 expression by short hairpin RNA completely abolished ephrin ligand-induced effects on adhesion and migration. Analysis of signal transduction identified p38, Erk, and mTOR as downstream signaling mediators potentially inducing the ephrin-B1 phenotype. In conclusion, the observed deregulation of Eph/ephrin expression in medulloblastoma enhances the invasive phenotype, suggesting a potential role in local tumor cell invasion and the formation of metastases.     

The roles of p38MAPK and caspase-3 in DADS-induced apoptosis in human HepG2 cells

Objectives

To explore the function of p38MAPK and caspase-3 in DADS-induced apoptosis in human HepG2 cells, and discuss the signal transduetion mechanism of HepG2 cells in the apoptosis process induced by DADS by using the inhibitors of p38MAPK (SB203580) and caspase-3 (Z-DEVD-FMK).

Methods

After the human HepG2 cells had been treated with the DADS and inhibitors for 24 h, cell viability was determined by the MTT method, apoptosis was evaluated by flow cytometry (FCM) and the expressions of p38MAPK and caspase-3 were measured by western-blot.

Results

Our results indicated that DADS activities the p38MAPK and caspase-3, but the inhibitors, SB203580 and Z-DEVD-FMK (for p38MAPKand for caspase-3, respectively), both have the effect of inhibitory activity on P38MAPK and caspase-3. Furthermore, a combination treatment with both DADS and inhibitor (SB203580 or Z-DEVD-FMK) decreases the inhibitory and apoptotic activity of HepG2 cells increased compared with DADS-treated.

Conclusions

Our data indicate that p38MAPK and caspase-3 are involved in the process of DADS-induced apoptosis in human HepG2 cells and interact with each other.     

p38MAPK 在结肠癌细胞凋亡中的作用及与COX-2 的关系

 目的 探讨结肠癌细胞p38MAPK介导celecoxib（COX-2选择性抑制剂）抗肿瘤的作用及与COX-2的关系。方法 用MTT法检测celecoxib对人结肠癌HT-29细胞生长的作用，用Western blot法测定各组细胞COX-2和Phosph—p38MAPK蛋白表达量，采用流式细胞术检测celecoxib和SB203580（p38MAPK特异性抑制剂）作用后HT-29细胞凋亡和细胞周期分布。结果 p38MAPK和COX-2蛋白表达量与对照组（0．23±0.12）（0.95±0．14）相比，celecoxib可使p38MAPK蛋白表达水平明显升高（0．62±0．11），而使COX-2蛋白表达水平降低（0、44±0．11）；SB203580使p38MAPK（0.12±0．05）及COX-2蛋白（0、23±0．13）表达水平均降低；SB203580和celecoxib共同作用后，p38MAPK表达量介于celecoxib和SB203580作用之间（0．43±0．12），COX-2表达量下降最为显著（0．15±0．10））。celecoxib和eeleeoxib＋SB203580均可显著诱导HT-29细胞凋亡（P〈0．01和P〈0．05），与对照纽（4．31％）相比，其凋亡率分别为40．95％、26．24％。结论 在HT29细胞中，celecoxib可通过活化p38MAPK而诱导结肠癌细胞凋亡，p38MAPK是COX-2的上游激酶，COX-2的表达水平受p38MAPK调控，并且COX-2可能对p38MAPK有负反馈调节作用。celecoxib是通过COX-2及其以外的p38MAPK通路诱导肿瘤细胞凋亡而发挥抗肿瘤作用的。     

Analysis of the drug resistance profile of multidrug resistance protein 7 (ABCC10): resistance to docetaxel

The multidrug resistance protein (MRP) family consists of nine members that can be categorized according to whether or not a third (NH(2)-terminal) membrane-spanning domain is present. Three (MRP1, MRP2, and MRP3) of the four members that have this structural feature are able to confer resistance to natural product anticancer agents. We previously established that MRP7, the remaining family member that has three membrane-spanning domains, possesses the cardinal biochemical activity of MRPs in that it is able to transport amphipathic anions such as 17beta-estradiol 17-(beta-d-glucuronide). However, the drug resistance profile of the pump has not been determined. In this study, the drug resistance capabilities of MRP7 are evaluated by analyzing the resistance profiles of two clones of HEK293 cells in which the pump was ectopically expressed. MRP7-transfected HEK293 cells exhibited the highest levels of resistance toward docetaxel (9-13-fold). In addition, lower levels of resistance were observed for paclitaxel (3-fold), vincristine (3-fold), and vinblastine (3-4-fold). Consistent with the operation of an ATP-dependent efflux pump, MRP7-transfected cells exhibited reduced accumulation of radiolabeled paclitaxel compared with HEK293 cells transfected with parental plasmid. These results indicate that MRP7, unlike other MRPs, is a resistance factor for taxanes.     

Reactive oxygen species and p38 MAPK regulate Bax translocation and calcium redistribution in salubrinal-induced apoptosis of EBV-transformed B cells

Salubrinal is a specific eIF2α phosphatase inhibitor that inhibits ER stress-mediated apoptosis. However, maintaining hyper-phosphorylated eIF2α state with high doses of salubrinal treatment promotes apoptosis in some cancer cells. In this report, we found that salubrinal induced apoptosis of EBV-transformed B cells. Notably, salubrinal induced ROS generation and p38 MPAK activation, which then induced expression of FasL. Moreover, salubrinal subsequently led to activation of caspases, calcium redistribution, Bax translocation, cytochrome c release, and apoptosis. These findings suggest that salubrinal may be a novel therapeutic approach for EBV-associated malignant diseases.     

The role of the MKK6/p38 MAPK pathway in Wip1-dependent regulation of ErbB2-driven mammary gland tumorigenesis

There is increasing evidence for the role of wild-type p53 induced phosphatase 1 (Wip1) phosphatase in the regulation of tumorigenesis. To evaluate Wip1 as a breast cancer oncogene, we generated a mouse strain with targeted expression of Wip1 to the breast epithelium. We found that these mice are prone to cancer when intercrossed with transgenics expressing the ErbB2 oncogene but not conditional knockouts for Brca2. This tumor-prone phenotype of Wip1 is fully eliminated through attenuation of proliferation by activating the MKK6/p38 mitogen-activated protein kinases (MAPK) cascade in mice bearing a constitutively active form of MKK6. We propose that Wip1 phosphatase operates within the MKK6/p38 MAPK signaling pathway to promote ErbB2-driven mammary gland tumorigenesis.