Therapeutic implication of vascular endothelial growth factor receptor-1 (VEGFR-1) targeting in cancer cells and tumor microenvironment by competitive and non-competitive inhibitors

Quantitative examination of the inhibitory activation of molecular targeting agents in hepatocellular carcinoma patient-derived cell invasion via a novel in vivo tumor model

BACKGROUND

The outcomes for patients with advanced hepatocellular carcinoma (HCC) receiving sorafenib are far from satisfactory because of treatment resistance to sorafenib. However, the exact mechanism of resistance to sorafenib remains unclear and it is valuable to establish a novel mouse model to quantitatively analyze the inhibition rates of sorafenib on the invasive growth of HCC cells in the liver.

METHODS

HCC tissue microblocks derived from patients were cultured and mixed with hydrogel drops. Then, hydrogel drops containing microblocks of HCC tissue were attached onto the surface of the livers of nude mice to form lesions or nodules of HCC. The mice received molecular targeting agents through oral administration. Livers with tumor nodules were harvested for H&E staining (hematoxylin-eosin staining) analysis and H&E staining images were quantitatively analyzed using image J software. The invasive growth of HCC cells into the liver was calculated using the depth of the lesions compared with the total thickness of the liver.

RESULTS

Microblocks containing cells derived from HCC patients can form lesions in the liver of nude mice. Oral administration of molecular targeting agents inhibited the invasive growth of HCC cells in the liver of nude mice.

CONCLUSIONS

The model established in this study involves the invasive growth of HCC cells in the liver of nude mice, and the model allows for the quantitative analysis of the inhibitory effect of molecular targeting agents on the invasion of HCC cells in vivo.

Role of VEGFR-1 in melanoma acquired resistance to the BRAF inhibitor vemurafenib

The vascular endothelial growth factor receptor‐1 (VEGFR‐1) is a tyrosine kinase receptor frequently expressed in melanoma. Its activation by VEGF‐A or placental growth factor (PlGF) promotes tumour cell survival, migration and invasiveness. Moreover, VEGFR‐1 stimulation contributes to pathological angiogenesis and induces recruitment of tumour‐associated macrophages. Since melanoma acquired resistance to BRAF inhibitors (BRAFi) has been associated with activation of pro‐angiogenic pathways, we have investigated VEGFR‐1 involvement in vemurafenib resistance. Results indicate that human melanoma cells rendered resistant to vemurafenib secrete greater amounts of VEGF‐A and express higher VEGFR‐1 levels compared with their BRAFi‐sensitive counterparts. Transient VEGFR‐1 silencing in susceptible melanoma cells delays resistance development, whereas in resistant cells it increases sensitivity to the BRAFi. Consistently, enforced VEGFR‐1 expression, by stable gene transfection in receptor‐negative melanoma cells, markedly reduces sensitivity to vemurafenib. Moreover, melanoma cells expressing VEGFR‐1 are more invasive than VEGFR‐1 deficient cells and receptor blockade by a specific monoclonal antibody (D16F7 mAb) reduces extracellular matrix invasion triggered by VEGF‐A and PlGF. These data suggest that VEGFR‐1 up‐regulation might contribute to melanoma progression and spreading after acquisition of a drug‐resistant phenotype. Thus, VEGFR‐1 inhibition with D16F7 mAb might be a suitable adjunct therapy for VEGFR‐1 positive tumours with acquired resistance to vemurafenib.

Dietary compound glycyrrhetinic acid suppresses tumor angiogenesis and growth by modulating antiangiogenic and proapoptotic pathways in vitro and in vivo

Glycyrrhetinic acid (GA) is a major bioactive compound of licorice. The objective of this study was to investigate the effects of GA on ovarian cancer, particularly those related to angiogenesis and apoptosis, and to elucidate the underlying mechanisms of action. In vitro studies showed that GA significantly inhibited proliferation, migration, invasion and tube formation in human umbilical vein endothelial cells (HUVECs) in a concentration-dependent manner. GA inhibited the phosphorylation of major receptors and enzymes involved in angiogenesis, such as VEGFR2, mTOR, Akt, ERK1/2, MEK1/2, p38 and JNK1/2 in HUVECs. In addition, GA induced apoptosis, loss of mitochondrial membrane potential and cell cycle arrest in G1 phase in A2780 ovarian cancer cells. The proapoptotic effect of GA involved the increased phosphorylation of p38 and JNK1/2; increased cleavage of caspase 3, caspase 9 and PARP; reduced phosphorylation of mTOR, Akt and ERK1/2; and reduced expressions of survivin and cyclin D1. Ex vivo studies showed that GA significantly inhibited microvessel sprouting in rat aortic ring model. In vivo studies showed that GA inhibited the formation of new blood vessels in zebrafish and mouse Matrigel plug. GA also significantly reduced the size of ovarian cancer xenograft tumors in nude mice. Taken together, GA possesses potential antitumor effects, and the underlying mechanisms may involve the inhibition of signaling pathways related to angiogenesis and the activation of apoptotic pathways in cancer cells. Our findings suggest that GA could serve as an effective regimen in the prevention or treatment of cancer.

VEGFR-1 Regulates EGF-R to Promote Proliferation in Colon Cancer Cells

The relationship between epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) pathways in tumor growth is well established. EGF induces VEGF production in cancer cells, and the paracrine VEGF activates vascular endothelial cells to promote tumor angiogenesis and thus supports tumor cell growth in an angiogenesis-dependent manner. In this study, we found angiogenesis-independent novel crosstalk between the VEGF and the EGF pathways in the regulation of colon cancer cell proliferation. Stimulation of colon cancer cells with VEGF-A and placental growth factor (PlGF) activated VEGF receptor-1 (VEGFR-1) and increased proliferation activity in an autocrine EGF/EGF receptor (EGF-R)-dependent manner. Mechanistically, VEGFR-1 interacted with and stabilized EGF-R, leading to increased EGF-R protein levels and prolonged its expression on cell surface plasma membrane. In contrast, VEGFR-1 blockade by a neutralizing antibody and an antagonistic peptide of VEGFR-1 suppressed the complex formation of VEGFR-1 and EGF-R and decreased EGF-R expression via a lysosome-dependent pathway, resulting in the suppression of proliferation activity. Our results indicated that VEGFR-1 regulated EGF-R expression to promote proliferation activity in a cell-autonomous-dependent manner.

The TGF-β/Smad Pathway Inhibitor SB431542 Enhances The Antitumor Effect Of Radiofrequency Ablation On Bladder Cancer Cells

Background

Despite progress achieved in bladder cancer (BC) treatment, the prognosis of patients with advanced BC (ie, metastasized from the bladder to other organs) is poor. Although mortality in cases of low-grade BC is rare, the treatment, such as a radical cystectomy, often has a serious impact on the quality of life. Thus, research is needed to identify more effective treatment strategies and this work is aiming to examine the potential application of combination of radiofrequency ablation (RFA) and SB435142, a inhibitor of transforming growth factor β (TGFβ)/Smad pathway.

Methods

BC cells were transplanted into nude mice (thymusdeficiency Bal B/c) to form subcutaneous tumors. The mice with subcutaneous tumors were then treated with RFA and oral administration of SB431542, an inhibitor of TGFβ/Smad signaling pathway. The antitumor effect of RFA was measured by tumor proliferation curves and micro-positron emission computed tomography (micro-PET). The effect of SB431542 on epithelial-mesenchymal transition (EMT) related regulators in subcutaneous tumor tissues formed by BC cells were examined by quantitative real-time polymerase chain reaction (qPCR) experiments.

Results

The SB431542 treatment enhanced the antitumor effect of RFA on subcutaneous growth of BCs. SB431542 also decreased EMT-related regulators in subcutaneous tumor tissues formed by BC cells in nude mice.

Conclusion

SB431542 enhances the effect of RFA on BC.

Rational MD simulations for improvement the affinity of nanobody against PlGF (placenta growth factor): mutagenesis based on electrostatic interactions

AbbreviationsCOMcenter of mass distanceMDmolecular dynamicsMM-PBSAMolecular Mechanics Poisson-Boltzmann Surface AreaNbnanobodyPlGFplacenta growth factorRgradius of gyrationRMSDroot mean-square deviationSASAsolvent-accessible surface areaVEGFvascular endothelial growth factor.

SREBP-1 inhibitor Betulin enhances the antitumor effect of Sorafenib on hepatocellular carcinoma via restricting cellular glycolytic activity

Lipid metabolism that correlates tightly to the glucose metabolic regulation in malignant cells includes hepatocellular carcinoma (HCC) cells. The transcription factor Sterol Regulatory Element Binding Protein 1 (SREBP-1), a regulator of fatty acid synthesis, has been shown to pivotally regulate the proliferation and metastasis of HCC cells. However, the intrinsic mechanism by which SREBP-1 regulates the survival of HCC cells remains unclear. In this study, among HCC patients who had dismal responses to Sorafenib, a high SREBP-1 level was found in the tumors and correlated to poor survival. This observation suggested the negative role of SREBP-1 in clinical HCC prognosis. Our mechanistical studies reveal that the inhibition of SREBP-1 via its inhibitor Betulin suppresses cellular glucose metabolism. In addition to the reduced glycolytic activity, a thwarted metastatic potential was observed in HCC cells upon Betulin administration. Moreover, our data show that SREBP-1 inhibition facilitated the antitumor effects of Sorafenib on HCC cells and xenograft tumors.

miR-596 suppresses the expression of Survivin and enhances the sensitivity of osteosarcoma cells to the molecular targeting agent anlotinib

Background

Osteosarcoma (OSA), the most common primary bone malignancy, is characterized by a wide spectrum of complicated pathologies and frequent distal metastasis and causes death in adolescents and young adults worldwide. Antitumor drug treatment strategies include various cytotoxic chemotherapy drugs, while molecular targeted therapy for OSA is currently less used. The present work revealed the role played by the miR-596/Survivin axis in affecting the sensitivity of OSA cells to anlotinib, a novel molecular targeting agent.

Methods

By virtual screening, we found that miR-596 might target Survivin by using an online tool (miRDB). RNA levels of miR-596 and Survivin in clinical specimens were examined with qPCR. The effect of miR-596 on anlotinib’s antitumor effect was examined with MTT experiments, the subcutaneous tumor model, or the intramuscular tumor model.

Results

Overexpression of miR-596 via lentiviral particles repressed the protein level of Survivin in U2OS cells. Transfection of miR-596 enhanced the antitumor effect of anlotinib on U2OS cells or five cell lines derived from OSA patients.

Conclusion

miR-596 targets Survivin and enhances the antitumor effect of anlotinib on OSA cells.

Chelidonine enhances the antitumor effect of lenvatinib on hepatocellular carcinoma cells

Background

Lenvatinib is a newly approved molecular targeted drug for the treatment of advanced hepatocellular carcinoma (HCC). However, the high cost associated with this treatment poses a huge financial burden on patients and the entire public health system. Therefore, there is an urgent need to develop novel strategies that enhance the antitumor effect of lenvatinib.

Methods

The antitumor effects of chelidonine or/and lenvatinib on HCC cell lines MHCC97-H and LM-3 were examined using the 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2- H-tetrazolium bromide (MTT) assay. For the in-vivo investigation, the effect on subcutaneous or intrahepatic tumor growth in nude mice was also determined. The mRNA levels of epithelial mesenchymal transition (EMT)-related factors were examined through quantitative polymerase chain reaction or Western blot.

Results

In the present study, we found that treatment with chelidonine enhanced the apoptotic effect of lenvatinib on HCC cells and the in-vivo growth of HCC tumors in nude mice. Mechanistically, treatment with chelidonine increased the expression of epithelial indicator E-cadherin, whereas it decreased the expression of mesenchymal indicators N-cadherin and Vimentin. These findings suggest that chelidonine restricted the EMT in HCC cells.

Conclusion

Chelidonine inhibits the process of EMT and enhances the antitumor effect of lenvatinib on HCC cells.

On the Horizon: Targeting Next-Generation Immune Checkpoints for Cancer Treatment

BACKGROUND

Immune checkpoints are critical regulatory pathways of the immune system which finely tune the response to biological threats. Among them, the CD-28/CTLA-4 and PD-1/PD-L1 axes play a key role in tumour immune escape and are well-established targets of cancer immunotherapy.

SUMMARY

The clinical experience accumulated to date provides unequivocal evidence that anti-CTLA-4, PD-1, or PD-L1 monoclonal antibodies, used as monotherapy or in combination regimes, are effective in a variety of advanced/metastatic types of cancer, with improved clinical outcomes compared to conventional chemotherapy. However, the therapeutic success is currently restricted to a limited subset of patients and reliable predictive biomarkers are still lacking. Key Message: The identification and characterization of additional co-inhibitory pathways as novel pharmacological targets to improve the clinical response in refractory patients has led to the development of different immune checkpoint inhibitors, the activities of which are currently under investigation. In this review, we discuss recent literature data concerning the mechanisms of action of next-generation monoclonal antibodies targeting LAG-3, TIM-3, and TIGIT co-inhibitory molecules that are being explored in clinical trials, as single agents or in combination with other immune-stimulating agents.

Oridonin synergistically enhances the anti-tumor efficacy of doxorubicin against aggressive breast cancer via pro-apoptotic and anti-angiogenic effects

The therapeutic outcomes of doxorubicin (Dox) treatment in breast cancer are limited by decreased drug efficiency and cardiotoxicity. The aim of this study was to investigate whether oridonin (Ori), a natural chemical abundant in the Chinese herb Isodon rubescens, might potentiate the anticancer effects, and decrease the adverse cardiotoxic effects, of Dox. On the basis of the optimized drug ratio determined through combination index calculations, we evaluated the synergistic effects and potential mechanisms of combining Dox with Ori to suppress breast cancer growth and angiogenesis both in vitro and in vivo. Dox plus Ori synergistically induced apoptosis in MDA-MB-231 cells, in a manner involving regulation of the Bcl-2/Bax, PARP, Caspase 3 and Survivin signaling pathways. Additionally, Ori increased the intracellular accumulation of Dox in MDA-MB-231 cells. Moreover, Dox plus Ori significantly decreased the proliferation, migration, invasion and tube formation of HUVECs. The underlying anti-angiogenic mechanism may have been due to the inhibition of VEGFR2-mediated signaling. Computational docking analysis further demonstrated that Dox plus Ori had high affinity toward the ATP-binding domain of VEGFR-2 kinase. Consistently with these findings, in vivo studies indicated that Ori enhanced the antitumor effect of Dox via activating apoptosis and inhibiting blood vessel formation at tumor sites. Moreover, Ori reversed the Dox-induced cardiotoxicity in a mouse model. In conclusion, our findings provide strong evidence that Ori may be highly promising in enhancing the efficacy of Dox and decreasing its adverse cardiotoxic effects, thus suggesting that Ori may serve as a potential adjunct therapy during Dox-based chemotherapy.

Atezolizumab and Bevacizumab Attenuate Cisplatin Resistant Ovarian Cancer Cells Progression Synergistically via Suppressing Epithelial-Mesenchymal Transition

The AURELIA trial demonstrated that adding Bevacizumab to chemotherapy significantly improved progression-free survival (PFS) for platinum resistant recurrent ovarian cancer. Recently, immunotherapy also presented potential anti-tumor effects in several malignant solid tumors. This study aimed to investigate whether combining anti-PD-L1 Atezolizumab with BEV may have a synergistic effect and enhance the efficacy of both treatments in cisplatin resistant epithelial ovarian cancer (CREOC). We retrospectively analyzed 124 epithelial ovarian cancer (EOC) patients from Gynecologic Oncology Department of Tianjin Cancer Hospital between January 2013 and June 2018, who all were diagnosed with cisplatin resistance due to progressing <6 months after completing platinum-based therapy. Based on responding to at least 2 cycles of Bevacizumab-containing chemotherapy (BC), these Patients were divided into BC response group and BC non-response group. Immunohistochemistry was used to detect that PD-L1 expression and tumor angiogenesis-related proteins (VEGF and Semaphorin4D) in tissues from 124 patients with CREOC. The positive expressions of PD-L1, VEGF, and Semaphorin4D (SEMA4D) were found in 58.73, 50.79, and 71.43% of the 63 cases CREOC tissues with BC response, respectively, which were significantly higher than that in the 61 cases BC non-response group (P < 0.05). PD-L1 expression correlated with SEMA4D and VEGF positively (r = 0.344 and 0.363, P < 0.001). Over-expressions of PD-L1, VEGF and SEMA4D are associated with more malignant clinicopathologic characteristics of CREOC Patients. In survival analysis, patients' response to BC was the independent factor for evaluation of PFS and overall survival (OS). Cell functional assays showed that Atezolizumab in combination with Bevacizumab inhibited the proliferation, migration, and invasion of cisplatin resistant ovarian cancer cell line A2780cis in vitro synergistically, which maybe associate with Bevacizumab suppressing the epithelial-mesenchymal transition (EMT) and PD-L1 expression by targeting STAT3. Furthermore, Bevacizumab and Atezolizumab induced synergistic anti-tumor effect in vivo. These findings suggest a novel therapeutic strategy for cisplatin resistant recurrent EOC and its mechanism warrants further study.

SIRT1 inhibits hepatocellular carcinoma metastasis by promoting M1 macrophage polarization via NF-κB pathway

Background

Tumor-associated macrophages (TAMs) serve as crucial modulators of the complicated interaction between cancer cells and immune microenvironment. Sirtuin 1 (SIRT1) has an impact on immune reactions in cancer progression. Current knowledge of the role of SIRT1 in the regulation of M1-like macrophages as well as in hepatocellular carcinoma (HCC) is insufficient.

Methods

SIRT1 expression in HCC tissues was detected using quantitative reverse transcriptase PCR (qRT-PCR) and Western blot. M1 markers were detected by qRT-PCR and flow cytometry assay. Moreover, the influence of SIRT1 on HCC cell apoptosis, migration, and invasion was studied using transwell assay, flow cytometry assay, and TUNEL assays, respectively.

Results

In this study, it was revealed that SIRT1 was upregulated in patients suffering from HCC; these patients were also shown to have elevated levels of M1-like TAM infiltration. SIRT1 was able to reinforce M1-like macrophage infiltration and inhibit HCC metastasis. Furthermore, SIRT1 enhanced NF-κB stimulation, promoting phosphorylation of p65, IκB, and IκB kinase. It was further demonstrated in our study that SIRT1 had an impact on polarization of M1 through the NF-κB pathway. NF-κB repression downregulated M1 markers in macrophages, which excessively expressed SIRT1 and counteracted the influence of SIRT1 on migration of HCC cells.

Conclusion

Taken together, these results offer proof that SIRT1 is an essential regulator of the immune reaction that counteracts malignant HCC cell migration as well as growth, indicating that macrophage SIRT1 could serve as an innovative target to treat HCC.

A Single-Arm, Phase II Study of Apatinib in Refractory Metastatic Colorectal Cancer

LESSONS LEARNED

Patients with metastatic colorectal cancer with good performance status or no liver metastasis could benefit from apatinib.Circulating tumor DNA abundance may be a predictor in serial monitoring of tumor load.

BACKGROUND

Apatinib, an oral vascular endothelial growth factor (VEGF) receptor-2 inhibitor, has been approved as third-line treatment for metastatic gastric cancer in China. The aim of this study was to evaluate the efficacy and safety of apatinib, in the treatment of patients with refractory metastatic colorectal cancer after failure of two or more lines of chemotherapy.

METHODS

In this open-label, single-arm, phase II study, patients with histological documentation of adenocarcinoma of the colon or rectum were eligible if they had received at least two prior regimens of standard therapies including fluoropyrimidine, oxaliplatin, and irinotecan. These patients were treated with apatinib in a daily dose of 500 mg, p.o., in the third-line or higher setting. Capture sequencing was dynamically performed to identify somatic variants in circulating tumor DNA (ctDNA) with a panel of 1,021 cancer-related genes. The primary endpoint was progression-free survival (PFS) and the tumor response was determined according to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Interim analysis was applied as predefined.

RESULTS

From June 1, 2016 to December 31, 2017, 26 patients were enrolled. The median PFS of the whole group was 3.9 months (95% confidence interval [CI]: 2.1-5.9). The median overall survival (OS) was 7.9 months (95% CI: 4.6-10.1+). Patients with performance status (PS) 0-1 had longer PFS than those with PS 2 (4.17 months vs. 1.93 months, p = .0014). Patients without liver metastasis also had longer PFS than those who had live metastasis (5.87 months vs. 3.33 months, p = .0274). The common side effects of apatinib were hypertension, hand-foot syndrome, proteinuria, and diarrhea. The incidence of grade 3-4 hypertension, hand-foot syndrome, proteinuria, and diarrhea was 76.92%, 11.54%, 73.08%, and 23.08%, respectively. All of the patients received dose reduction because of adverse effect. Results of capture sequencing showed APC, TP53, and KRAS were most frequently mutant genes. ctDNA abundance increased before the radiographic assessment in ten patients.

CONCLUSION

Apatinib monotherapy showed promising efficiency for patients with refractory colorectal cancer, especially in patients with PS 0-1 or no liver metastasis. ctDNA abundance may be a predictor in serial monitoring of tumor load.