Long noncoding RNA RP11-70C1.3 confers chemoresistance of breast cancer cells through miR-6736-3p/NRP-1 axis.

Chemoresistance remains a major obstacle for improving the clinical outcome of patients with breast cancer. Recently, long noncoding RNAs (lncRNAs) have been implicated in breast cancer chemoresistance. However, the function and underlying mechanism are still largely unknown. Using lncRNA microarray, we identified 122 upregulated and 475 downregulated lncRNAs that might be related to the breast cancer chemoresistance. Among them, RP11-70C1.3 was one of the most highly expressed lncRNAs. In breast cancer patients, high RP11-70C1.3 expression predicted poor prognosis. Knockdown of RP11-70C1.3 inhibited the multidrug resistance of breast cancer cells in vitro and in vivo. Further investigations revealed that RP11-70C1.3 functioned as a competing endogenous RNA (ceRNA) for miR-6736-3p to increase NRP-1 expression. Notably, the rescue experiments showed that both miR-6736-3p inhibitor and NRP-1 overexpression could partly reverse the suppressive influence of RP11-70C1.3 knockdown on breast cancer chemoresistance. In conclusion, our study indicated that lncRNA RP11-70C1.3 regulated NRP-1 expression by sponging miR-6736-3p to confer chemoresistance of breast cancer cells. RP11-70C1.3 might be a potential therapeutic target in enhancing the clinical efficacy of chemotherapy in breast cancer.

Autophagy inhibition potentiates the anti-angiogenic property of multikinase inhibitor anlotinib through JAK2/STAT3/VEGFA signaling in non-small cell lung cancer cells.

BACKGROUND: The efficacy and safety of multikinase inhibitor anlotinib have been confirmed in the treatment of advanced non-small cell lung cancer (NSCLC). However, the direct functional mechanisms of tumor lethality mediated by anlotinib were not fully elucidated, and the underlying mechanisms related to resistance remain largely elusive. METHODS: Cell viability, colony formation, apoptosis and tumor growth assays were performed to examine the effect of anlotinib on lung cancer cells in vitro and in vivo. The punctate patterns of LC3-I/II were detected by confocal microscopy. HUVECs motility was detected using Transwell and scratch wound-healing assay. To visualize the microvessels, tubular formation assay was performed. The expression of LC3-I/II and beclin-1 and the changes of JAK2/STAT3/VEGFA pathway were detected by western blotting. The VEGFA levels in tumor supernatant were measured by ELISA. RESULTS: Anlotinib treatment decreased cell viability and induced apoptosis in Calu-1 and A549 cells. Moreover, anlotinib induced human lung cancer cell autophagy in a dose- and time-dependent manner. Blocking autophagy enhanced the cytotoxicity and anti-angiogenic ability of anlotinib as evidenced by HUVECs migration, invasion, and tubular formation assay. Co-administration of anlotinib and chloroquine (CQ) further reduced VEGFA level in the tumor supernatant, compared with that of anlotinib or CQ treatment alone. When autophagy was induced by rapamycin, the JAK2/STAT3 pathway was activated and VEGFA was elevated, which was attenuated after deactivating STAT3 by S3I-201. Further in vivo studies showed that anlotinib inhibited tumor growth, induced autophagy and suppressed JAK2/STAT3/VEGFA pathway, and CQ enhanced this effect. CONCLUSION: Anlotinib induced apoptosis and protective autophagy in human lung cancer cell lines. Autophagy inhibition further enhanced the cytotoxic effects of anlotinib, and potentiated the anti-angiogenic property of anlotinib through JAK2/STAT3/VEGFA signaling.

Role of the NRP-1-mediated VEGFR2-independent pathway on radiation sensitivity of non-small cell lung cancer cells.

PURPOSE: To determine if inhibiting neuropilin-1 (NRP-1) affects the radiosensitivity of NSCLC cells through a vascular endothelial growth factor receptor 2 (VEGFR2)-independent pathway, and to assess the underlying mechanisms. METHODS: The expression of VEGFR2, NRP-1, related signaling molecules, abelson murine leukemia viral oncogene homolog 1 (ABL-1), and RAD51 were determined by RT-PCR and Western blotting, respectively. Radiosensitivity was assessed using the colony-forming assay, and the cell apoptosis were analyzed by flow cytometry. RESULTS: We selected two cell lines with high expression levels of VEGFR2, including Calu-1 cells that have high NRP-1 expression, and H358 cells that have low NRP-1 expression. Upon inhibition of p-VEGFR2 by apatinib in Calu-1 cells, the expression of NRP-1 protein and other related proteins in the pathway was still high. Upon NRP-1 siRNA treatment, the expression of both NRP-1 and RAD51 decreased (p < 0.01; p < 0.05). Upon ABL-1 siRNA treatment, the expression of NRP-1 was increased and the expression of RAD51 was unchanged. Calu-1 cells treated with NRP-1 siRNA exhibited significantly higher apoptosis and radiation sensitivity in radiation therapy compared to Calu-1 cells treated with apatinib alone (p < 0.01; p < 0.01). The apoptosis and radiation sensitivity in H358 cells with NRP-1 overexpression was similar to the control group regardless of VEGFR2 inhibition. CONCLUSIONS: We demonstrated that when VEGFR2 was inhibited, NRP-1 appeared to regulate RAD51 expression through the VEGFR2-independent ABL-1 pathway, consequently regulating radiation sensitivity. In addition, the combined inhibition of VEGFR2 and NRP-1 appears to sensitize cancer cells to radiation.

A Pilot Study of Apatinib as Third-Line Treatment in Patients With Heavily Treated Metastatic Colorectal Cancer.

BACKGROUND: Antiangiogenic therapy has shown improved clinical outcome in metastatic colorectal cancer (mCRC). After the failure of standard treatments, regorafenib and TAS-102 would be recommended for patients with mCRC, however, they have not been approved in China during this study period. PATIENTS AND METHODS: This pilot study aimed to assess the efficacy and safety of apatinib, a novel oral inhibitor targeting vascular endothelial growth factor receptor 2, as third-line treatment for patients with mCRC refractory to standard therapies. In this retrospective study, all patients received apatinib treatment until progressive disease (PD), death, unacceptable toxicity, and curative surgery. The dose or treatment schedule was modified according to the physician's discretion according to the toxicity profiles. RESULTS: Between March 2015 and June 2017, 36 patients were enrolled and eligible for evaluation of the safety and efficacy. One patient (2.8%) achieved complete response, 3 (8.3%) achieved partial response, 24 (66.7%) achieved stable disease, and 8 (22.2%) PD. The objective response rate and the disease control rate were 11.1% (4 of 36), and 77.8% (28 of 36), respectively. Moreover, the median overall survival (OS) since the initiation of first-line treatment was 33.2 months. The median progression-free survival (PFS) and median OS from apatinib treatment were 4.8 and 10.1 months, respectively. Intergroup analysis showed that there was no significant difference in median PFS and median OS between patients who were previously treated with and without bevacizumab. The most common Grade 3 to 4 adverse reactions were hand-foot syndrome, hypertension, and proteinuria. CONCLUSION: Our results suggested that apatinib was active as a third-line treatment of refractory mCRC with a manageable tolerability profile. In addition, preliminary data suggested that the efficacy of apatinib would not be affected by previous bevacizumab treatment. Further prospective randomized controlled clinical trials are urgently needed.

The role and significance of VEGFR2+ regulatory T cells in tumor immunity.

Tumor development is closely related to angiogenesis, and VEGFR2 plays an important role in tumor angiogenesis. It is broadly expressed in the blood vessels, especially in the microvessels of tumor tissues. Furthermore, VEGFR2 is detected on the surface of the cell membrane in various immune cells, such as dendritic cells, macrophages, and regulatory T cells (Tregs). Tregs, which are one of the key negative regulatory factors in tumor immune microenvironments, show high-level expression of VEGFR2 which participates in the regulation of immunosuppressive function. VEGFR2+ Tregs play a potent suppressive role in the formation of immunosuppressive microenvironments. A large number of reports have proven the synergistic effects between targeted therapy for VEGFR2 and immunotherapy. The depression of VEGFR2 activity on T cells can significantly reduce the infiltration of Tregs into the tumor tissue. Targeted therapy for VEGFR2+ Tregs also provides a new choice for the clinical treatment of malignant solid tumors. In this paper, the role and significance of VEGFR2+ Tregs in tumor immunity in recent years are reviewed.

Apatinib concurrent gemcitabine for controlling malignant ascites in advanced pancreatic cancer patient: A case report.

RATIONALE: Malignant ascites (MA) is one of the poor prognostic factors for advanced pancreatic cancer and can bring about serious symptoms. The improvement of quality of life for patients is priority. However, there is no standard method for the treatment for pancreatic cancer-mediated MA. Apatinib is a novel and highly selective tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor-2. There are no reports of concurrent apatinib with gemcitabine in patients with pancreatic cancer-mediated MA. PATIENT CONCERNS: Herein, we presented a 64-year-old man patient who visited hospital due to abdominal pain for 1 month. DIAGNOSES: He was initially diagnosed with pancreatic cancer and his first symptom was MA. INTERVENTIONS: After failing in tube drainage and gemcitabine therapy, the patient received gemcitabine combined apatinib orally and after administrated 1 month, the MA was evaluated as nearly clear response according to the RECIST 1.1 standard, and without further need of paracentesis. The CEA and CA199 reached the lowest level after administrating for 2.5 months during the treatment process. OUTCOMES: 10.5 months following apatinib administration, the patient achieved a progression-free survival for more than 11 months. Hypertension (grade IV), hand-foot syndrome (grade I) and proteinuria (grade II) were observed. LESSONS: It indicated that apatinib concurrent gemcitabine may be a superior choice for pancreatic cancer-mediated MA. Further clinical trials required to confirm its efficacy and safety.