244-MPT overcomes gefitinib resistance in non-small cell lung cancer cells

Application status and future prospects of the PDX model in lung cancer

Lung cancer is one of the most prevalent, fatal, and highly heterogeneous diseases that, seriously threaten human health. Lung cancer is primarily caused by the aberrant expression of multiple genes in the cells. Lung cancer treatment options include surgery, radiation, chemotherapy, targeted therapy, and immunotherapy. In recent decades, significant progress has been made in developing therapeutic agents for lung cancer as well as a biomarker for its early diagnosis. Nonetheless, the alternative applications of traditional pre-clinical models (cell line models) for diagnosis and prognosis prediction are constrained by several factors, including the lack of microenvironment components necessary to affect cancer biology and drug response, and the differences between laboratory and clinical results. The leading reason is that substantial shifts accrued to cell biological behaviors, such as cell proliferative, metastatic, invasive, and gene expression capabilities of different cancer cells after decades of growing indefinitely in vitro. Moreover, the introduction of individualized treatment has prompted the development of appropriate experimental models. In recent years, preclinical research on lung cancer has primarily relied on the patient-derived tumor xenograft (PDX) model. The PDX provides stable models with recapitulate characteristics of the parental tumor such as the histopathology and genetic blueprint. Additionally, PDXs offer valuable models for efficacy screening of new cancer drugs, thus, advancing the understanding of tumor biology. Concurrently, with the heightened interest in the PDX models, potential shortcomings have gradually emerged. This review summarizes the significant advantages of PDXs over the previous models, their benefits, potential future uses and interrogating open issues.

A Method for the Establishment of Human Lung Adenocarcinoma Patient-Derived Xenografts in Mice

Patient-derived xenografts (PDXs) are created by implanting human tumor tissue or cells into immunodeficent mice, and enable the study of tumor biology, biomarkers and response to therapy in vivo. This chapter describes a method for lung adenocarcinoma (LAC) PDX generation using subcutaneous implantation of tumor tissue and cell suspensions and incorporating the humanization of PDX models by reconstitution with human immune cells.

Formononetin inhibits tumor growth by suppression of EGFR-Akt-Mcl-1 axis in non-small cell lung cancer

Background

Epidermal growth factor receptor (EGFR) activating mutations play crucial roles in the tumorigenesis of human non-small cell lung cancer (NSCLC). The mechanism regarding how EGFR signaling regulates myeloid cell leukemia sequence 1 (Mcl-1) protein stability and ubiquitination remains undefined.

Methods

MTS assay was used for natural product library screening. The effect of formononetin (Formo) on NSCLC cells was determined by MTS assay and soft agar assay. Molecular modeling was performed to analyze the potential different binding modes between Formo and EGFR WT or mutants. Mcl-1 protein level and the inhibitory effect of Formo on EGFR signaling were examined by immunoblot, in vitro kinase assay, in vitro pulldown and ATP competition assays, co-immunoprecipitation assay, ubiquitination analysis, in vivo xenograft model, and immunohistochemical staining.

Results

Formo was identified as an EGFR inhibitor by a 98 commercially available natural product screening. Formo suppresses WT and mutant EGFR kinases activity in vitro, ex vivo, and in vivo. Molecular modeling indicates that Formo docks into the ATP-binding pocket of both WT and mutant EGFR. Formo inhibits EGFR-Akt signaling, which in turn activates GSK3β and promotes Mcl-1 phosphorylation in NSCLC cells. Treatment with Formo enhances the interaction between Mcl-1 and SCF^Fbw7, which eventually promotes Mcl-1 ubiquitination and degradation. Depletion of either GSK3β or SCF^Fbw7 compromised Formo-induced Mcl-1 downregulation. Finally, Formo inhibits the in vivo tumor growth in a xenograft mouse model.

Conclusion

This study highlights the importance of promoting ubiquitination-dependent Mcl-1 turnover might be an alternative strategy to enhance the anti-tumor efficacy of EGFR-TKI.

Deguelin suppresses non-small cell lung cancer by inhibiting EGFR signaling and promoting GSK3β/FBW7-mediated Mcl-1 destabilization

Activating mutations of epidermal growth factor receptor (EGFR) play crucial roles in the oncogenesis of human non-small cell lung cancer (NSCLC). By screening 79 commercially available natural products, we found that the natural compound deguelin exhibited a profound anti-tumor effect on NSCLC via directly down-regulating of EGFR-signaling pathway. Deguelin potently inhibited in vitro EGFR kinase activity of wild type (WT), exon 19 deletion, and L858R/T790M-mutated EGFR. The in silico docking study indicated that deguelin was docked into the ATP-binding pocket of EGFRs. By suppression of EGFR signaling, deguelin inhibited anchorage-dependent, and independent growth of NSCLC cell lines, and significantly delayed tumorigenesis in vivo. Further study showed that deguelin inhibited EGFR and downstream kinase Akt, which resulted in the activation of GSK3β and eventually enhanced Mcl-1 phosphorylation at S159. Moreover, deguelin promoted the interaction between Mcl-1 and E3 ligase SCF^FBW7, which enhanced FBW7-mediated Mcl-1 ubiquitination and degradation. Additionally, phosphorylation of Mcl-1 by GSK3β is a prerequisite for FBW7-mediated Mcl-1 destruction. Depletion or pharmacological inactivation of GSK3β compromised deguelin-induced Mcl-1 ubiquitination and reduction. Taken together, our data indicate that enhancement of ubiquitination-dependent Mcl-1 turnover might be a promising approach for cancer treatment.

Investigating the mechanism by which SMAD3 induces PAX6 transcription to promote the development of non-small cell lung cancer

Background

This study investigated the function of SMAD3 (SMAD family member 3) in regulating PAX6 (paired box 6) in non-small cell lung cancer.

Methods

First, qRT-PCR was employed to detect SMAD3 expression in cancer tissues along with normal tissues and four cell lines, including BEAS-2B, H125, HCC827 and A549 cells. SMAD3 was knocked down by small interference RNA (siRNA), and then its expression was determined via qRT-PCR and Western blot analysis. The correlation between SMAD3 and PAX6 was determined by double luciferase reporter experiments and chromatin immunoprecipitation (ChIP) assay. Cell viability was evaluated by CCK-8 and colony forming assays, while cell migration and invasion were detected by Transwell analysis.

Results

SMAD3 and PAX6 were upregulated in lung cancer tissues and cancer cells. Knocking down SMAD3 and PAX6 by transfection with siRNAs specifically suppressed the expression of SMAD3 and PAX6 mRNA and protein levels. SMAD3 could promote PAX6 transcriptional activity by binding to its promoter. Reduced expression of SMAD3 led to the downregulation of PAX6 mRNA and protein levels along with decreased cell migration, invasion, proliferation and viability in A549 and HCC827 cells. PAX6 overexpression altered the si-SMAD3-induced inhibition of cell migration, invasion, proliferation and viability in A549 and HCC827 cells. Additionally, PAX6 knockdown alone also repressed the cell migration, invasion, proliferation and viability of the cell lines.

Conclusions

SMAD3 promotes the progression of non-small cell lung cancer by upregulating PAX6 expression.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0948-z) contains supplementary material, which is available to authorized users.

Tyrosine kinase inhibitor-induced IL-6/STAT3 activation decreases sensitivity of EGFR-mutant non-small cell lung cancer to icotinib

Tyrosine kinase Inhibitors (TKIs) of epidermal growth factor receptor (EGFR) has considerably benefited for non-small cell lung carcinomas (NSCLC) harbor mutations in EGFR. However, the factors attenuating EGFR-TKI efficiency are obstacles to inhibit the proliferation of EGFR-mutant NSCLC cells successfully. Clarifying the insensitivity mechanisms of EGFR-TKI would help to develop new treatment strategy. In this study, the sensitivity of EGFR-mutant NSCLC cell lines, PC9 and HCC827, to icotinib was detected. Similar with other EGFR-TKIs such as gefitinib and erlortinib in previous research, the proliferation of two cell lines was apparently inhibited. However, we surprisingly found that contrast with the suppression of EGFR-AKT/ERK pathway, STAT3 was significantly activated in PC9 cells with the treatment of icotinib, but not in HCC827 cells. Further study confirmed that icotinib concomitantly induced IL-6 secretion and src activation in PC9 cells. Moreover, with the treatment of IL-6 neutralizing antibody or src inhibitor, dasatinib, icotinib-induced phosphorylation of STAT3 was reduced, as well as the sensitivity of PC9 to icotinib was also partially increased. Our results suggest that Src/IL-6/STAT3 bypass pathway is activated to maintain cell survival when the EGFR pathway was inhibited by TKIs, even in some EGFR-mutant NSCLC cells sensitive to TKIs. This finding provides a groundwork for potential combinatorial treatment with TKIs and Src or STAT3 inhibitor to improve icotinib sensitivity.

Establishment of lung cancer patient-derived xenograft models and primary cell lines for lung cancer study

Background

The overall 5-year survival rate of lung cancer is about 15% even with therapeutic drugs like tyrosine kinase inhibitors. Ideal models are urgently needed for exploring mechanisms and finding new drugs. Patient-derived xenografts (PDX) models and primary cells are both used to screen therapeutic regimens for cancer. However, PDX models and primary cells from the same patient are difficult to establish. Their consistency to the original tumor tissue is not well studied.

Methods

31 lung cancer patient tissues were procured to establish the lung cancer PDX models and primary cell lines. Tumor growth measurements, histological and immunohistochemistry analysis, Western blotting, EGFR and K-RAS mutation detection and gefitinib sensitive assay were performed to evaluate the characteristic of established PDX models. Immunofluorescence analysis, anchorage-independent cell growth, Western blotting and gefitinib sensitive assay were performed to assay the characteristic of established primary cell lines. The whole-exome sequencing was used to compare the characteristic of the patient’s tumor tissue, established PDX and primary cell line.

Results

Twenty-one lung cancer PDX models (67.74%, 21/31) and ten primary cell lines (32.25%, 10/31) were established from patients’ tumor tissues. The histology and pathological immunohistochemistry of PDX xenografts are consistent with the patients’ tumor samples. Various signal pathways were activated in different PDX models (n = 5) and primary cell lines (n = 2). EGFR mutation PDX model and primary cell line (LG1) were sensitive to gefitinib treatment. The expression of CK8/18, TTF1 and NapsinA in LG1 and LG50 primary cells were also positive. And the activated signal pathways were activated in LG1 and LG50 primary cell lines. Furthermore, the gene mutation in PDX tumor tissues and primary cell line (LG50) was consistent with the mutation in LG50 patient’s tumor tissues.

Conclusion

These data suggested that established lung cancer PDX models and primary cell lines reserved mostly molecular characteristics of primary lung cancer and could provide a new tool to further understand the mechanisms and explore new therapeutic strategies.

MLN4924 suppresses neddylation and induces cell cycle arrest, senescence, and apoptosis in human osteosarcoma

Neddylation is a post-translational protein modification process associated with carcinogenesis and cancer development. MLN4924, a pharmaceutical neddylation inhibitor, induces potent anti-cancer effects in multiple types of cancers. In this study, we investigated the effects of MLN4924 on human osteosarcoma (OS). Levels of both NEDD8 activating enzyme E1 (NAE1) and ubiquitin-conjugating enzyme E2M (Ube2M), two critical components of the neddylation pathway, were much higher in OS tissues and cells than in normal osseous tissues and cells. MLN4924 treatment led to DNA damage, reduced cell viability, senescence and apoptosis in OS cells. Moreover, MLN4924 inhibited OS xenograft tumor growth in mice. Mechanistically, MLN4924 blocked the neddylation of cullins and induced accumulation of several tumor-suppressive substrates of Cullin-RING E3 ubiquitin ligases (CRLs), including CDT1, Wee1, p21, p27, Noxa, and p16. These results suggest clinical studies investigating the utility of MLN4924 for the treatment of OS are warranted.

Losmapimod Overcomes Gefitinib Resistance in Non-small Cell Lung Cancer by Preventing Tetraploidization

The epidermal growth factor receptor (EGFR) is known to play a critical role in non-small cell lung cancer (NSCLC). Constitutively active EGFR mutations, including in-frame deletion in exon 19 and L858R point mutation in exon 21, contribute about 90% of all EGFR-activating mutations in NSCLC. Although oral EGFR-tyrosine kinase inhibitors (TKIs), gefitinib and erlotinib, show dramatic clinical efficacy with significantly prolonged progression-free survival in patients harboring these EGFR-activating mutations, most of these patients will eventually develop acquired resistance. Researchers have recently named genomic instability as one of the hallmarks of cancer. Genomic instability usually involves a transient phase of polyploidization, in particular tetraploidization. Tetraploid cells can undergo asymmetric cell division or chromosome loss, leading to tumor heterogeneity and multidrug resistance. Therefore, identification of signaling pathways involved in tetraploidization is crucial in overcoming drug resistance. In our present study, we found that gefitinib could activate YAP-MKK3/6-p38 MAPK-STAT3 signaling and induce tetraploidization in gefitinib-resistance cells. Using p38 MAPK inhibitors, SB203580 and losmapimod, we could eliminate gefitinib-induced tetraploidization and overcome gefitinib-resistance. In addition, shRNA approach to knockdown p38α MAPK could prevent tetraploidy formation and showed significant inhibition of cancer cell growth. Finally, in an in vivo study, losmapimod could successfully overcome gefitinib resistance using an in-house established patient-derived xenograft (PDX) mouse model. Overall, these findings suggest that losmapimod could be a potential clinical agent to overcome gefitinib resistance in NSCLC.

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Gefitinib induces tetraploidy formation in gefitinib-resistant NSCLC cells

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YAP-MKK3/6-p38 MAPK signaling is essential for tetraploidization

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Losmapimod, a p38 MAPK inhibitor, overcomes gefitinib-resistance both in vitro and PDX xenograft mode

Gefitinib is a targeted drug therapy in non-small cell lung cancer (NSCLC) which shows dramatic clinical efficacy. However, most of these patients eventually develop drug resistance. Although researchers have identified different mechanisms contributing to the drug resistance, developing a single therapy to overcome the drug resistance remains difficult. In this study, we find that tetraploidization of cancer cells through YAP-MKK3/6-p38 MAPK signaling could be one of the common mechanisms in developing the drug resistance. By using losmapimod, we could eliminate tetraploidization and overcome gefitinib resistance in an animal model suggesting that losmapimod could be a potential clinical agent to overcome gefitinib resistance in NSCLC.

Inhibiting proliferation and migration of lung cancer using small interfering RNA targeting on Aldo-keto reductase family 1 member B10

Lung cancer is the leading cause of global cancer‑associated mortality. Genomic alterations in lung cancers have not been widely characterized, however, the molecular mechanism of tumor initiation and progression remain unknown, and no molecularly targeted have been specifically developed for its treatment and diagnosis. The present study observed the upregulation of Aldo‑keto reductase family 1 member Bio10 (AKR1B10) lung cancer tissues by analyzing two public lung cancer gene expression datasets. Further experiments in silencing AKR1B10 demonstrated that the expression of AKR1B10 was associated with cell proliferation, cell cycle, adhesion and invasion, as well as extracellular‑signal‑regulated kinase/mitogen activated protein kinase signal pathway. The overexpression of AKR1B10 in lung cancer indicates the important role of AKR1B10 in tumorigenesis. These findings suggest that AKR1B10 could be a potential diagnosis and treatment mark of lung cancer.

Combination curcumin and (-)-epigallocatechin-3-gallate inhibits colorectal carcinoma microenvironment-induced angiogenesis by JAK/STAT3/IL-8 pathway

Tumor microenvironment has a crucial role in cancer development and progression, whereas the mechanism of how it regulates angiogenesis is unclear. In this study, we simulated the colorectal carcinoma microenvironment by conditioned medium (CM) of colorectal carcinoma cell lines (SW620, HT-29, HCT116) supernatant or colorectal carcinoma tissue homogenate supernatant to induce normal endothelial cells (NECs). We found that colorectal carcinoma CM promoted tumor angiogenesis by coercing NECs toward tumor endothelial cells (TECs) with the activation of the JAK/STAT3 signaling pathway. Antibody array analysis showed HT-29 supernatant contained numerous angiogenesis-related proteins, especially IL-8. Interestingly, the production of IL-8 in NECs induced by HT-29 CM was also increased. We also verified the crucial role of IL-8 in promoting the CM-induced angiogenesis, as IL-8 repression by neutralizing antibody abolished the transition of NECs toward TECs. Curcumin and (-)-epigallocatechin-3-gallate (EGCG) are broadly investigated in cancer chemoprevention. However, poor bioavailability hurdles their application alone, and the mechanism of their anti-angiogenesis still need to be illuminated. Here, we found that curcumin combination with EGCG attenuated the tumor CM-induced transition of NECs toward TECs by inhibiting JAK/STAT3 signaling pathway. Furthermore, the combination of curcumin and EGCG markedly reduced tumor growth and angiogenesis in the colorectal carcinoma PDX mouse model, and the combined anti-angiogenic effect was better than that of curcumin or EGCG alone. Taken together, our findings provide a new mechanism of tumor angiogenesis, and the combination of curcumin and EGCG represents a potential anti-angiogenic therapeutic method for colorectal carcinoma.

Metformin inhibits esophageal squamous cell carcinoma-induced angiogenesis by suppressing JAK/STAT3 signaling pathway

Although it has been known that the tumor microenvironment affects angiogenesis, the precise mechanism remains unclear. In this study, we simulated the microenvironment of human esophageal squamous cell carcinoma (ESCC) by tumor conditioned medium (TCM) to assess the influence on normal endothelial cells (NECs). We found that the TCM-induced NECs showed enhanced angiogenic properties, such as migration, invasion and tube formation. Moreover, the TCM-induced NECs expressed tumor endothelial cells (TECs) markers at higher levels, which indicated that TCM probably promoted tumor angiogenesis by coercing NECs to change toward TECs. The microarray gene expression analysis indicated that TCM induced great changes in the genome of NECs and altered many regulatory networks, especially c-MYC and JAK/STAT3 signaling pathway. More importantly, we investigated the anti-angiogenic effect of metformin, and found that metformin abrogated the ESCC microenvironment-induced transition of NECs toward TECs by inhibiting JAK/STAT3/c-MYC signaling pathway. Furthermore, we verified the anti-angiogenic activity of metformin in vivo by a human ESCC patient-derived xenograft (PDX) mouse model for the first time. Taken together, our research provides a novel mechanism for the anti-angiogenic effect of metformin, and sets an experimental basis for the development of new anti-angiogenic drugs by blocking the transition of NECs toward TECs, which possibly open new avenues for targeted treatment of cancer.

Astragaloside IV sensitizes non-small cell lung cancer cells to gefitinib potentially via regulation of SIRT6

Astragaloside IV, the active component of Astragalus membranaceus, exhibits diverse biological roles including the anti-tumor activity. In this study, we evaluated the chemosensitive role of astragaloside IV in non-small cell lung cancer cells. Cell Counting Kit-8 analysis was performed to determine cell viability. Real-time polymerase chain reaction and western blot were used to measure the messenger RNA and protein expression. Results showed that astragaloside IV treatment could suppress the proliferation of non-small cell lung cancer cells. In addition, combined treatment with astragaloside IV remarkably enhanced the chemosensitivity to gefitinib in three non-small cell lung cancer cell lines including NCI-H1299, HCC827, and A549. Furthermore, compared with gefitinib-treated cells, the messenger RNA expression of SIRT6 was obviously increased in non-small cell lung cancer cells treated with gefitinib combined with astragaloside IV. In addition, downregulation of SIRT6 was accomplished using small interference RNA technology. As a result, SIRT6 inhibition abolished the sensitization role of astragaloside IV in non-small cell lung cancer cells. Taken together, these data demonstrated that astragaloside IV sensitized tumor cells to gefitinib via regulation of SIRT6, suggesting that astragaloside IV may serve as potential therapeutic approach for lung cancer.

Feedback Activation of STAT3 as a Cancer Drug-Resistance Mechanism

Signal transducer and activator of transcription 3 (STAT3) plays crucial roles in several cellular processes such as cell proliferation and survival, and has been found to be aberrantly activated in many cancers. Much research has explored the leading mechanisms for regulating the STAT3 pathway and its role in promoting tumorigenesis. We focus here on recent evidence suggesting that feedback activation of STAT3 plays a prominent role in mediating drug resistance to a broad spectrum of targeted cancer therapies and chemotherapies. We highlight the potential of co-targeting STAT3 and its primary target to overcome drug resistance, and provide perspective on repurposing clinically approved drugs as STAT3 pathway inhibitors, in combination with the FDA-approved receptor tyrosine kinase (RTK) inhibitors, to improve clinical outcome of cancer treatment.