CXCR4 Signaling Induced Epithelial-Mesenchymal Transition by PI3K/AKT and ERK Pathways in Glioblastoma

miR-22 inhibits the proliferation, motility, and invasion of human glioblastoma cells by directly targeting SIRT1

Recently, microRNAs (miRNAs), a kind of small and non-coding RNA, can target the downstream molecules. Increasing evidence demonstrates that miRNAs meditate the onset and progression of a variety of tumors. In the present study, we carried out gene transfection, western blot, and reverse transcription PCR (RT-PCR) to explore the role of miR-22 in glioblastoma tissues and cell lines. Here, we verified that the expression of miR-22 was downregulated in glioblastoma tissues and cells rather than matched non-tumor tissues and normal human astrocyte (NHA) cells (p < 0.001). By contrast, SIRT1 messenger RNA (mRNA) and protein were upregulated in glioblastoma tissues and cells (p < 0.001). In vitro miR-22 mimics interfered with cell proliferation, migration, and invasion of U87 and U251 cells. Mechanically, the 3'-untranslated regions (3'-UTRs) of SIRT1 were a direct target of miR-22, leading to the decreased expression of SIRT1 protein in U87 and U251 cells. Meanwhile, miR-22 mimics also inhibited the expression of epidermal growth factor receptor (EGFR) and matrix metallopeptidase 9 (MMP9). In conclusion, miR-22 inhibited cell proliferation, migration, and invasion via targeting the 3'-UTR of SIRT1 in the progression of glioblastoma and miR-22-SIRT1 pathway can be recommended as a potential target for treatment of glioblastoma.

Regulation of CXCR4/AKT-signaling-induced cell invasion and tumor metastasis by RhoA, Rac-1, and Cdc42 in human esophageal cancer

CXC chemokines and their cognate receptors have been implicated wildly in cancer pathogenesis. In the present study, we report a critical cause relationship between CXCR4 expression and tumorigenesis in the setting of human esophageal squamous cell carcinoma (ESCC). In ESCC cells, CXCR4 expression was significantly higher than in human esophageal epithelial cells (HEEC). Reduction of CXCR4 in ESCC cells reduced cell proliferation and invasion in vitro and tumor growth in vivo. Among the potential downstream targets of CXCR4-CXCL12 are RhoA, Rac-1, and Cdc42, which are likely to contribute to the invasiveness of ESCC cells. Finally, we found that CXCR4-CXCL12/AKT axis regulates RhoA, Rac-1, and Cdc42 to modulate cell invasion and tumor metastasis. Together, these results demonstrate a role for CXCR4 in ESCC metastasis and progression and suggest potential targets for therapeutic intervention.

Expression of chemokine receptor CXCR4 is closely correlated with clinical outcome in human nasopharyngeal carcinoma

The CXC chemokine receptor 4 (CXCR4) has been reported to be involved in the development and progression of nasopharyngeal carcinoma (NPC). However, the role of CXCR4 in clinical outcome and prognosis of NPC patients remains controversial. In the present study, we investigated and reviewed the expression of CXCR4 in NPC tissues and then analyzed the definitive role of CXCR4 in clinical outcome and prognosis. Here, we found that the expression level of CXCR4 was significantly higher in NPC cancer specimens (61/98) than that in paired non-tumor tissues (p < 0.001). Together with our pathological analysis, statistic analysis revealed that CXCR4 expression was indeed closely correlated with UICC stage (p = 0.000), N stage (p = 0.019), and metastasis (p = 0.000). Most importantly, the systematic review combined with our survival and multivariate analysis that revealed high expression of CXCR4 was obviously associated with poor overall survival (OS) (p = 0.000) and progression-free survival (PFS) (p = 0.000) and can act as an independent prognostic factor in NPC patients. In conclusion, this study suggests that CXCR4 is highly activated and expressed in the development of NPC and may be recommended as an indicator in the diagnosis of NPC. Thus, targeting of CXCR4 gene or protein could be used as a potential therapy for NPC.

The involvement of anterior gradient 2 in the stromal cell-derived factor 1-induced epithelial-mesenchymal transition of glioblastoma

In recent years, it has been widely identified that the stromal cell-derived factor 1 (SDF-1) and anterior gradient 2 (AGR2) were implicated in the development of epithelial-mesenchymal transition (EMT) in a variety of cancers. However, the involvement of SDF-1-AGR2 pathway in the EMT of glioblastoma has not been investigated. In the present study, the in vitro assays were used to investigate the role of AGR2 in cell cycle, migration, and invasion. We found that the expressions of AGR2 and chemokine (C-X-C motif) receptor 4 (CXCR4) were obviously upregulated in glioblastoma cells T98G, A172, U87, and U251 than those in normal human astrocytes (NHA) (all p < 0.01), among which both U87 and U251 cells presented the highest expression (p > 0.05). Western blot revealed that SDF-1 induced the expression of p-AKT, AGR2, and EMT markers (N-cadherin, matrix metalloproteinase-2 (MMP2), and Slug) in a dose-dependent manner in U87 and U251 cells. However, the depletion of AGR2 reversed SDF-1-induced upregulation of EMT markers rather than p-AKT. Furthermore, functional analysis identified that knockdown of AGR2 induced cell cycle arrest in G0/G1 phase and suppressed the migration and invasion of U87 and U251 cells. Taken together, SDF-1-CXCR4 pathway induced the expression of AGR2 to control the progression of EMT likely via AKT pathway in the development of glioblastoma. Our findings lay a promising foundation for the SDF-1-AGR2 axis-targeting therapy in patients with glioblastoma.

SDF1-CXCR4 signaling contributes to persistent pain and hypersensitivity via regulating excitability of primary nociceptive neurons: involvement of ERK-dependent Nav1.8 up-regulation

BACKGROUND

Pain is one critical hallmark of inflammatory responses. A large number of studies have demonstrated that stromal cell-derived factor 1 (SDF1, also named as CXCL12) and its cognate receptor C-X-C chemokine receptor type 4 (CXCR4) play an important role in immune reaction and inflammatory processes. However, whether and how SDF1-CXCR4 signaling is involved in inflammatory pain remains unclear.

METHODS

Under the intraplantar (i.pl.) bee venom (BV) injection-induced persistent inflammatory pain state, the changes of SDF1 and CXCR4 expression and cellular localization in the rat dorsal root ganglion (DRG) were detected by immunofluorescent staining. The role of SDF1 and CXCR4 in the hyperexcitability of primary nociceptor neurons was assessed by electrophysiological recording. Western blot analysis was used to quantify the DRG Nav1.8 and phosphorylation of ERK (pERK) expression. Behavioral tests were conducted to evaluate the roles of CXCR4 as well as extracellular signal-regulated kinase (ERK) and Nav1.8 in the BV-induced persistent pain and hypersensitivity.

RESULTS

We showed that both SDF1 and CXCR4 were dramatically up-regulated in the DRG in i.pl. BV-induced inflammatory pain model. Double immunofluorescent staining showed that CXCR4 was localized in all sizes (large, medium, and small) of DRG neuronal soma, while SDF1 was exclusively expressed in satellite glial cells (SGCs). Electrophysiological recording showed that bath application with AMD3100, a potent and selective CXCR4 inhibitor, could reverse the hyperexcitability of medium- and small-sized DRG neurons harvested from rats following i.pl. BV injection. Furthermore, we demonstrated that the BV-induced ERK activation and Nav1.8 up-regulation in the DRG could be blocked by pre-antagonism against CXCR4 in the periphery with AMD3100 as well as by blockade of ERK activation by intrathecal (i.t.) or intraplantar (i.pl.) U0126. At behavioral level, the BV-induced persistent spontaneous pain as well as primary mechanical and thermal hypersensitivity could also be significantly suppressed by blocking CXCR4 and Nav1.8 in the periphery as well as by inhibition of ERK activation at the DRG level.

CONCLUSIONS

The present results suggest that peripheral inflammatory pain state can trigger over release of SDF1 from the activated SGCs in the DRG by which SGC-neuronal cross-talk is mediated by SDF1-CXCR4 coupling that result in subsequent ERK-dependent Nav1.8 up-regulation, leading to hyperexcitability of tonic type of the primary nociceptor cells and development and maintenance of persistent spontaneous pain and hypersensitivity.

Upregulated miRNA-622 inhibited cell proliferation, motility, and invasion via repressing Kirsten rat sarcoma in glioblastoma

Glioblastoma has been reported as one of the leading causes of cancer-related death, and some factors including oncogenic genes and environments are involved in tumorigenesis. MicroRNAs (miRNAs) act as a kind of small and noncoding RNA, which can target the downstream molecules. Emerging reports demonstrate that microRNAs regulate the initiation and progression of different cancers. In the present study, we conducted in vitro experiment as well as clinical studies in a cohort of 20 glioblastoma samples. We demonstrated that miR-622 expression was lower in tumor tissues and cells, when compared to normal brain tissues and normal human astrocyte (NHA) cells, while K-Ras messenger RNA (mRNA) and protein showed the opposite expression profile. Overexpression of miR-622 suppressed tumor cell proliferation, migration, and invasion of A172, U87, and U251 cells. Accordingly, the proliferating cell nuclear antigen (PCNA), matrix metallopeptidase 2 (MMP2), and MMP9 expressions were also decreased due to miR-622 overexpression. Importantly, we discovered that wild Kirsten rat sarcoma (K-Ras) was a direct target of miR-622, which decreased the expression of K-Ras protein in A172, U87, and U251 cells. In conclusion, upregulated miRNA-622 inhibited cell proliferation, migration, and invasion via repressing K-Ras in the progression of glioblastoma, and miR-622-K-Ras pathway can be recommended as a potential target for treatment of glioblastoma.

The involvement of hematopoietic pre-B cell leukemia transcription factor-interacting protein in regulating epithelial-mesenchymal transition of human spinal glioblastoma

To date, hematopoietic pre-B cell leukemia transcription factor-interacting protein (HPIP), a co-repressor for the transcription factor PBX, has been involved into the initiation and onset in a wide variety of cancers. However, the molecular mechanisms underlying HPIP-induced epithelial-mesenchymal transition (EMT) in the spinal glioblastoma have been under investigation. In the present study, spinal glioblastoma tissues, U87, and U251 cell lines were used and subjected to in vitro assays, such as RT-PCR, and Western blot. Here, in vitro assays revealed that HPIP mRNA and protein were highly expressed in five cases of spinal glioblastoma tissues, compared with non-tumor tissues. Subsequently, in vitro experiments demonstrated HPIP promoted the U87 and U251 cell growth and regulated the G1/S phase transitions in U87 and U251 cell cycle, respectively, accompanied by the increased expression of cyclin A2, cyclin B1, and cyclin D1. Furthermore, HPIP increased the expression of N-cadherin, Slug, and MMP2, and decreased the expression of E-cadherin. By contrast, knockdown of HPIP reversed HPIP-induced EMT biomarkers, migration, and invasion in U87 and U251 cells. In conclusion, our findings identified HPIP plays an important role in the progression and EMT of spinal glioblastoma, by which cell growth is improved. Thus, HPIP gene or protein could act as a useful target in the clinical practice.

BAG3 regulates cell proliferation, migration, and invasion in human colorectal cancer

Bcl2-associated athanogene 3 (BAG3) has been reported to be elevated in various tumors. However, it is unclear whether BAG3 has a functional role in the initiation and progression of colorectal cancer (CRC). Here, we collected CRC samples and cell lines to validate the pathway by using gene and protein assays. RT-PCR showed that the expression of BAG3 mRNA in CRC tissues was obviously higher than that in non-tumor tissues (p < 0.001). Immunohistochemical analysis showed that immunoreactivity of BAG3 was found in most CRC tissues and strongly correlated with TNM stage (p = 0.001), differentiation (p = 0.003), and metastasis (p = 0.010). Low expression of BAG3 in HCT-8 significantly reduced cellular proliferation, migration, and invasion. The analysis of in vitro cell showed that HCT-8 cells were exposed to si-BAG3, and its growth was inhibited depending on modulation of cell cycle G1/S checkpoints and cell cycle regulators, involving cyclin D1, cyclin A2, and cyclin B1. Furthermore, suppression of the epithelial-mesenchymal transition (EMT) by si-BAG3 is linked to the decreased expression of E-cadherin and the increased expression of N-cadherin, vimentin, and MMP9. In conclusion, in the present study, we demonstrated that BAG3 overexpression plays a critical role in cell proliferation, migration, and invasion of colorectal cancer. Our data suggests targeted inhibition of BAG3 may be useful for patients with CRC.

The Crucial Role of Cyclin-Dependent Kinase-5-Ataxia-Telangiectasia Mutated Axis in ICH-Induced Neuronal Injury of Rat Model

Cyclin-dependent kinase 5 (CDK5) and ataxia-telangiectasia mutated (ATM) are involved in normal human neurodevelopment and serves as a switch between neuronal survival and death. However, the molecular mechanisms underlying CDK5-ATM-induced neuronal injury caused by intracerebral hemorrhage (ICH) remain unclear. In this work, we used rat ICH models and thrombin-induced cell models to investigate the potential role of CDK5-ATM signals. Our findings revealed that CDK5 protein levels and kinase activities (p-histone H1 expression) were enforced in hematoma-surrounding neuron tissues following ICH. Besides, the expression of p25, p-ATM, and active caspase-3 protein was also upregulated after ICH. According to in vitro assays, the expression of CDK5, p-ATM, and active caspase-3 was all upregulated in cell viability-decreasing ICH cell models. However, blocking of either CDK5 or ATM suppressed the phosphorylation of ATM and the expression of active caspase-3, and attenuated the inhibition of neuronal survival. When p35/p25 was silenced, CDK5-ATM pathway was further inhibited, and cell viability was obviously ameliorated. In conclusion, this work suggested that ATM could be phosphorylated by CDK5 to induce the active caspase-3 and neuronal injury when intracerebral hemorrhage or ischemia occurred. Thus, the CDK5-AMT signal pathway has an important role in ICH process and may be a therapeutic target to prevent brain injury.

Glioblastoma Circulating Cells: Reality, Trap or Illusion?

Metastases are the hallmark of cancer. This event is in direct relationship with the ability of cancer cells to leave the tumor mass and travel long distances within the bloodstream and/or lymphatic vessels. Glioblastoma multiforme (GBM), the most frequent primary brain neoplasm, is mainly characterized by a dismal prognosis. The usual fatal issue for GBM patients is a consequence of local recurrence that is observed most of the time without any distant metastases. However, it has recently been documented that GBM cells could be isolated from the bloodstream in several studies. This observation raises the question of the possible involvement of glioblastoma-circulating cells in GBM deadly recurrence by a “homing metastasis” process. Therefore, we think it is important to review the already known molecular mechanisms underlying circulating tumor cells (CTC) specific properties, emphasizing their epithelial to mesenchymal transition (EMT) abilities and their possible involvement in tumor initiation. The idea is here to review these mechanisms and speculate on how relevant they could be applied in the forthcoming battles against GBM.