MrgprF acts as a tumor suppressor in cutaneous melanoma by restraining PI3K/Akt signaling.

The incidence of cutaneous melanoma (CM) has been increasing annually worldwide. In this study, we identify that MrgprF, a MAS related GPR family member, is decreased in cutaneous melanoma tissues and cell lines due to hypermethylation of its promoter region, and show that patients with CM expressing high levels of MrgprF exhibit an improved clinical outcome. We demonstrate that MrgprF forced expression inhibits tumor cell proliferation, migration, xenograft tumor growth, and metastasis. On the contrary, MrgprF knockdown promotes tumor cell proliferation and transformation of immortalized human keratinocyte-HaCaT cells, supporting the inhibitory role of MrgprF during tumor progression. Mechanistic studies reveal that MrgprF reduces the phosphoinositol­3­kinase (PI3K) complex formation between p101 and p110γ subunits, the critical step for phosphatidylinositol-(3, 4)-P2 (PIP2) conversion to phosphatidylinositol-(3, 4, 5)-P3 (PIP3), and then reduces the activation of PI3K/Akt signaling. This effect can be reversed by Akt specific agonist SC79. In addition, AMG 706, a previously documented inhibitor for endothelial cell proliferation, is identified as a potential agonist for MrgprF, and can impede tumor growth both in vitro and in vivo. Taken together, our findings suggest that MrgprF, a novel tumor suppressor in cutaneous melanoma, may be useful as a therapeutic target in the future.

Neoadjuvant Immunotherapy for MSI-H/dMMR Locally Advanced Colorectal Cancer: New Strategies and Unveiled Opportunities.

Patients with locally advanced colorectal cancer (LACRC) have a high risk of recurrence and metastasis, although neoadjuvant therapy may provide some benefit. However, patients with high microsatellite instability/deficient mismatch repair (MSI-H/dMMR) LACRC receive little benefit from neoadjuvant chemoradiotherapy (nCRT) or neoadjuvant chemotherapy (nCT). The 2015 KEYNOTE-016 trial identified MSI-H/dMMR as a biomarker indicative of immunotherapy efficacy, and pointed to the potential use of immune checkpoint inhibitors (ICIs). In 2017, the FDA approved two ICIs (pembrolizumab and nivolumab) for treatment of MSI-H/dMMR metastatic CRC (mCRC). In 2018, the CheckMate-142 trial demonstrated successful treatment of mCRC based on "double immunity" provided by nivolumab with ipilimumab, a regimen that may become a standard first-line treatment for MSI-H mCRC. In 2018, the FDA approved nivolumab alone or with ipilimumab for patients who progressed to MSI-H/dMMR mCRC after standard chemotherapy. The FDA then approved pembrolizumab alone as a first-line treatment for patients with MSI-H/dMMR CRC that was unresectable or metastatic. There is now interest in using these drugs in neoadjuvant immunotherapy (nIT) for patients with MSI-H/dMMR non-mCRC. In 2020, the NICHE trial marked the start of using nIT for CRC. This novel treatment of MSI-H/dMMR LACRC may change the approaches used for neoadjuvant therapy of other cancers. Our review of immunotherapy for CRC covers diagnosis and treatment, clinical prognostic characteristics, the mechanism of nIT, analysis of completed prospective and retrospective studies, and ongoing clinical trials, and the clinical practice of using nIT for MSI-H/dMMR LACRC. Our team also proposes a new organ-preservation strategy for patients with MSI-H/dMMR low LARC.

Insulin-like growth factor 2 mRNA-binding protein 2-stabilized long non-coding RNA Taurine up-regulated gene 1 (TUG1) promotes cisplatin-resistance of colorectal cancer via modulating autophagy.

Long non-coding RNAs (lncRNAs) have been demonstrated to influence the chemoresistance of colorectal cancer (CRC). Therefore, the study is designed to investigate the regulatory function and mechanism of Taurine up-regulated gene 1 (TUG1) in the cisplatin resistance of CRC. qRT-PCR checked the expressions of TUG1, Insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2), and miR-195-5p in CRC tissues and cells. The TUG1 or miR-195-5p overexpression model was engineered in CRC cells, followed by treatment with DDP or the autophagy inhibitor (Chloroquine, CQ). CCK8 (Cell Counting Kit-8) and the colony formation experiment monitored cell proliferation. Flow cytometry examined apoptosis, Transwell tracked migration and invasion, and Western blot ascertained the protein profiles of autophagy proteins (LC3I/LC3II and Beclin1) and the HDGF/DDX5/ß-catenin pathway. Dual-luciferase gene reporter assay and RNA immunoprecipitation confirmed the binding correlation between TUG1 and miR-195-5p and between miR-195-5p and HDGF. Furthermore, in-vivo experiments in nude mice probed the function and mechanism of IGF2BP2 in CRC cell growth. The profiles of TUG1 and IGF2BP2 were elevated in CRC tissues, and IGF2BP2 enhanced TUG1's expression in CRC cells. TUG1 activated autophagy to facilitate CRC cells' resistance to DDP. TUG1 targets miR-195-5p, and miR-195-5p targets HDGF. Overexpression of miR-195-5p abated the cancer-promoting function of TUG1 and curbed the profile of the HDGF/DDX5/ß-catenin axis. TUG1 stabilized by IGF2BP2 boosted CRC cell proliferation, migration, migration, and autophagy via the miR-195-5p/HDGF/DDX5/ß-catenin axis, hence enhancing CRC cell's resistance to DDP.

miR-4323 targets hepatoma-derived growth factor (HDGF) to suppress colorectal cancer cell proliferation.

MicroRNAs (miRNAs) are regulators of cancer progression via directly binding to the 3' untranslated region (3'UTR) of target genes to control the activity of signaling network. Recent studies have revealed the function of several miRNAs in colorectal cancer, however, there are still numerous miRNAs which have not been studied yet. Herein, we showed that miR-4323 was a downregulated miRNA according to previous microarray data. The downregulation of miR-4323 was further confirmed in colorectal tumors via RT-qPCR. miR-4323 overexpression decreased cell proliferation rate via induction of cell apoptosis in colorectal cancer cells. Mechanistically, miR-4323 decreased ß-catenin and its downstream genes including c-Myc and MMP9 in colorectal cancer cells, indicating the inactivation of Wnt signaling. HDGF, an anti-apoptotic protein, was predicted by several software as a potential target of miR-4323. HDGF was experimentally verified as a target gene of miR-4323 using dual luciferase reporter assay. Ectopic expression of HDGF attenuated the effect of miR-4323 on cell proliferation and apoptosis in cells. Altogether, the data demonstrate a critical role of miR-4323 in the regulation of colorectal cancer.

PirB functions as an intrinsic suppressor in hippocampal neural stem cells.

Neural stem cells play pivotal roles during prenatal development and throughout life. Here, we report that Paired immunoglobulin-like receptor B (PirB) functions as a suppressor during brain neurogenesis in the adult mouse. PirB expression increased with age during development, and its deficiency promoted neural stem cell proliferation and differentiation in vivo and in vitro. Furthermore, we detected an increase in Type 1 neural stem cells in PirB-deficient mice compared to their wild-type littermates. PirB deficiency promoted stemness marker gene expression of Sox2 and KLF4 by activating Akt1 phosphorylation. These findings suggest that PirB inhibits the self-renewal and differentiation capacities of neural stem cells. Thus, PirB may have the potential to serve as a therapeutic target for treatment of reduced neurogenesis in adults due to aging or other pathological conditions.

Circ_0026344 restrains metastasis of human colorectal cancer cells via miR-183.

Background: CircRNA circ_0026344 was previously revealed as a tumour-suppressive gene in colorectal cancer (CRC) progression. The purpose of this research was to investigate the role of circ_0026344 in CRC cells metastasis induced by chemokines. Methods: Two human CRC cell lines SW480 and Caco-2 were treated by CCL20 and CXCL8. Cell proliferation, migration/invasion, expression of epithelial-mesenchymal transition (EMT) inducers and the expression of circ_0026344 were measured using sulforhodamine B assay, Transwell chamber, western blot and qRT-PCR, respectively. The effects of circ_0026344 on CRC cells migration/invasion and the expression of EMT inducers were evaluated. Moreover, the downstream miRNA and signalling pathways of circ_0026344 were studied. Results: CCL20 and CXCL8 synergized to facilitate the proliferation, migration and invasion of CRC cells. At the meantime, E-cadherin was downregulated, whereas N-cadherin, Vimentin and Snail were up-regulated by CCL20 and CXCL8 co-stimulation, which was accompanied by the mobilization of PI3K/AKT/ERK signalling. More interestingly, the expression of circ_0026344 was down-regulated by CCL20 and CXCL8 co-stimulation. Silence of circ_0026344 increased the migratory and invasive capacities of CRC cells and increased EMT process as well. Overexpression of circ_0026344 led to a contrary impact. miR-183 was negatively regulated by circ_0026344, and the inhibitory effects of circ_0026344 overexpression on Wnt/ß-catenin pathway were reversed when miR-183 was overexpressed. Conclusion: Overexpression of circ_0026344 restrained CRC metastasis and EMT induced by CCL20 and CXCL8 synergistical treatment. miR-183 was a downstream effector of circ_0026344, and the anti-tumour function of circ_0026344 might be involved in the repressed Wnt/ß-catenin signalling. Highlights CCL20 and CXCL8 synergize to decrease the expression of circ_0026344; Silence of circ_0026344 promotes CRC cells migration, invasion and EMT process; miR-183 is a downstream effector of circ_0026344.

Erlotinib inhibits colon cancer metastasis through inactivation of TrkB-dependent ERK signaling pathway.

The distal metastasis is the main cause of death in patients with colon cancer. Tyrosine receptor kinase B (TrkB) and ERK signals may be the potential targets for the treatment of colon cancer metastasis. This study aims to investigate whether erlotinib inhibits distant metastasis of colon cancer by regulating TrkB and ERK signaling pathway. Human colon adenocarcinoma cell lines (SW480 and Caco-2) pretreated with exogenous C-X-C motif chemokine ligand 8 (CXCL8) were used to assess the suppressive effect of erlotinib on tumor metastasis, including anoikis, epithelial-mesenchymal transformation (EMT), migration, and invasion. Through TrkB overexpression, Akt suppression, and ERK suppression, the roles of TrkB, Akt, and ERK in erlotinib-induced metastasis inhibition of colon cancer cells were explored. The results showed that erlotinib alleviated CXCL8-induced metastasis of the colon cancer cells. Overexpression of TrkB in colon cancer cells eliminated the effect of erlotinib on anoikis, inhibition of EMT, migration, and invasion, and downregulation of p-ERK and p-Akt. Furthermore, the inhibition of ERK activation instead of Akt activation was found to participate in erlotinib-mediated metastasis resistance, including anoikis, inhibition of EMT, migration, and invasion. In conclusion, erlotinib inhibits colon cancer cell anoikis resistance, EMT, migration, and invasion by inactivating TrkB-dependent ERK signaling pathway.

CXCL8 induces epithelial-mesenchymal transition in colon cancer cells via the PI3K/Akt/NF-κB signaling pathway.

The aim of the present study was to investigate the role of chemokine (C-X-C motif) ligand 8 (CXCL8) in the proliferation, invasiveness and metastasis of colon cancer and its role in the induction of epithelial-mesenchymal transition (EMT) via activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/nuclear factor-κB (NF-κB) pathway. The plasmid vector containing CXCL8 cDNA was transfected into LoVo cells using Lipofectamine 2000 reagent. Real-time PCR and western blot analyses were performed to determine expression of CXCL8. MTT growth inhibition, scratch and Transwell invasion assays were conducted to assess cell proliferation, migration and invasiveness of the CXCL8-transfected LoVo cells. Western blot analyses were conducted to measure the levels of phosphorylation of protein in the PI3K/Akt/NF-κB pathway in the CXCL8-transfected LoVo cells. Expression levels of CXCL8 mRNA and protein were significantly increased in the CXCL8-transfected LoVo cells compared with levels in the control and empty-vector cells (P<0.05). Overexpression of CXCL8 increased proliferation of the LoVo cells and significant differences in cell viability were observed 48 h after transfection (P<0.05) and remained significant at 72 and 96 h. CXCL8-transfected LoVo cells had a significantly higher migration rate and doubled invasion. The CXCL8-transfected LoVo cells exhibited an EMT-like phenotype, compared with control and empty-vector cells, with decreased expression of E-cadherin accompanied by increased expression of N-cadherin, vimentin and α-SMA. Overexpression of CXCL8 activated the PI3K/Akt/NF-κB pathway by promoting the phosphorylation of PI3K, Akt and NF-κB. Subcutaneous tumors were generated by subcutaneous injection of LoVo parental cells or CXCL8-transfected LoVo cells in BALB/c nude mice. The tumor growth was more rapid in the CXCL8-transfected group than that noted in the parental cell group. In conclusion, overexpression of CXCL8 induced cell proliferation, migration and invasion of colon cancer LoVo cells. CXCL8 may act through induction of EMT via the PI3K/AKT/NF-κB signaling axis.

CXCL8, overexpressed in colorectal cancer, enhances the resistance of colorectal cancer cells to anoikis.

Anoikis is a form of apoptosis which occurs when anchorage-dependent cells either show loss of adhesion or inappropriate adhesion. Only a few cancer cells that detach from the primary site of the tumor acquire the ability to resist anoikis and form metastasis. The mechanism underlying the resistance of colorectal cancer (CRC) cells to anoikis remains unclear. Interleukin-8 (alternatively known as CXCL8) is associated with CRC angiogenesis and progression. Here, we found that a high abundance of CXCL8 or TOPK strongly correlated with poor overall and disease-free survival of 186 patients with CRC. A combination of high CXCL8 and high TOPK expressions had the worst prognosis. We showed that CXCL8 expression was negatively correlated with anoikis in CRC cells. CXCL8 treatment enhanced the resistance of CRC cells to apoptosis, which was accompanied by the increase of TOPK, and the activation of AKT and ERK. Moreover, we demonstrated that the inhibition of either ERK or AKT by specific chemical inhibitors attenuated the CXCL8-mediated resistance to anoikis. Treatment with AKT inhibitor abolished the effects of CXCL8 on TOPK expression, suggesting that TOPK was downstream of AKT in the process of anoikis. Taken together, we demonstrated that CXCL8 is strongly implicated in the resistance of CRC cells to anoikis, and that the AKT, TOPK and ERK pathway may be a potential therapeutic target for CRC.

[Influence of preoperative chemoradiotherapy, preoperative chemotherapy, and operation on immunity function in middle or lower rectal cancer patients].

OBJECTIVE: To study the influence of preoperative chemoradiotherapy, preoperative chemotherapy, and operation alone on the cellular immunity in patients with middle or lower rectal cancer. METHODS: Ninety middle or lower rectal cancer patients were non-randomly divided into 3 equal groups: preoperative radiotherapy group, receiving conventional radiotherapy with a total dose of 30 Gy in 10 fractions completed within 2 weeks; preoperative chemoradiotherapy group, receiving 2 cycles of single-oral drug regimen (capecitabine 1000 mg/m(2) for 2 weeks as a cycle with an interval of 1 week) and then, i.e., 2 days later, receiving conventional radiotherapy as prescribed for the patients in the preoperative radiotherapy group; and operation alone group. Operation was performed on the patients of the former 2 groups 3 weeks after the completion of the relevant treatment. Blood samples were collected on the admission day, 1 day before operation, and 7 day and 1 month after operation. Flow cytometry was used to detect the levels of CD(3)(+), CD(4)(+), CD(8)(+), CD(4)(+)/CD(8)(+), and NK cells. RESULTS: There were no significant differences in the levels of CD(3)(+), CD(4)(+), CD(8)(+), CD(4)(+)/CD(8)(+), and NK cells before and after radiotherapy between the preoperative chemoradiotherapy group and preoperative chemotherapy group (all P > 0.05). 7 days after operation, the levels of CD(3)(+), CD(4)(+), CD(4)(+)/CD(8)(+), and NK cells were degraded and the CD(8)(+) level was increased significantly (all P < 0.05) in all 3 groups. One month after operation, the levels of CD(3)(+), CD(4)(+), CD(4)(+)/CD(8)(+), and NK cells were all significantly higher and the CD(8)(+) level was significantly lower than those before operation and 7 days after operation (all P < 0.05)in all 3 groups. There were no significant differences in the T cell number and the proportions of different categories of cells at different time points in these 3 group (all P < 0.05). CONCLUSION: Preoperative chemoradiotherapy and preoperative chemotherapy have no significant impact on the cellular immune function in the patients with rectal cancer.