Dual inhibition of EGFR and c-Met kinase activation by MJ-56 reduces metastasis of HT29 human colorectal cancer cells

Design, synthesis, and biological evaluation of 4-(2-fluorophenoxy)-7-methoxyquinazoline derivatives as dual EGFR/c-Met inhibitors for the treatment of NSCLC

In non-small cell lung cancer (NSCLC) treatment, aberrant expression of c-mesenchymal-epithelial transition factor (c-Met) has been identified as a driving factor in epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) resistance. Unfortunately, none of the EGFR/c-Met dual-target inhibitors have successfully passed clinical trials. Hence, based on molecular docking analysis and combination principles of EGFR and c-Met inhibitors, three series of 4-(2-fluorophenoxy)-7-methoxyquinazoline derivatives as new EGFR/c-Met inhibitors were designed, synthesized, and evaluated for their biological activities. Among these compounds, TS-41 displayed the best inhibitory activity against EGFRL858R and c-Met kinases, with an IC50 value of 68.1 nM and 0.26 nM respectively. Moreover, it also showed excellent inhibitory activity on three NSCLC cell lines A549-P, H1975 and PC-9 with IC50 values ranging from 1.48 to 2.76 μM. Flow cytometry assays demonstrated that TS-41 induced apoptosis and cell cycle arrest of A549-P cells in a concentration-dependent manner, corresponding to JC-1 staining assay results. Western blot analysis revealed that TS-41 significantly downregulated the phosphorylation of EGFR, c-Met, and downstream AKT at molecular level. Importantly, TS-41 exhibited potent in vivo anticancer efficacy in an A549-P-bearing allograft nude mouse model at a dose of 60 mg/kg with a tumor growth inhibition rate of 55.3 % compared with Afatinib (46.4 %), as well as low hemolytic toxicity and organ toxicity. Molecular docking results showed that TS-41 was well embedded into the cavity of EGFR (PDB: 5GMP) and c-Met (PDB: 3LQ8) proteins, respectively. In summary, TS-41 is a high-efficiency and low-toxicity EGFR/c-Met inhibitor for the treatment of NSCLC and is worthy of further exploration.

Epidermal growth factor receptor dual-target inhibitors as a novel therapy for cancer: A review

Overexpression of the epidermal growth factor receptor (EGFR) has been linked to several human cancers, including esophageal cancer, pancreatic cancer, anal cancer, breast cancer, and lung cancer, particularly non-small cell lung cancer (NSCLC). Therefore, EGFR has emerged as a critical target for treating solid tumors. Many 1st-, 2nd-, 3rd-, and 4th-generation EGFR single-target inhibitors with clinical efficacy have been designed and synthesized in recent years. Drug resistance caused by EGFR mutations has posed a significant challenge to the large-scale clinical application of EGFR single-target inhibitors and the discovery of novel EGFR inhibitors. Therapeutic methods for overcoming multipoint EGFR mutations are still needed in medicine. EGFR dual-target inhibitors are more promising than single-target inhibitors as they have a lower risk of drug resistance, higher efficacy, lower dosage, and fewer adverse events. EGFR dual-target inhibitors have been developed sequentially to date, providing new options for remission in patients with previously untreatable malignancies and laying the groundwork for a future generation of compounds. This paper introduces the EGFR family proteins and their synergistic effects with other anticancer targets, and provides a comprehensive review of the development of EGFR dual-target inhibitors in cancer, as well as the opportunities and challenges associated with those fields.

Development of Dual Inhibitors Targeting Epidermal Growth Factor Receptor in Cancer Therapy

Epidermal growth factor receptor (EGFR) is of great significance in mediating cell signaling transduction and tumor behaviors. Currently, third-generation inhibitors of EGFR, especially osimertinib, are at the clinical frontier for the treatment of EGFR-mutant non-small-cell lung cancer (NSCLC). Regrettably, the rapidly developing drug resistance caused by EGFR mutations and the compensatory mechanism have largely limited their clinical efficacy. Given the synergistic effect between EGFR and other compensatory targets during tumorigenesis and tumor development, EGFR dual-target inhibitors are promising for their reduced risk of drug resistance, higher efficacy, lower dosage, and fewer adverse events than those of single-target inhibitors. Hence, we present the synergistic mechanism underlying the role of EGFR dual-target inhibitors against drug resistance, their structure-activity relationships, and their therapeutic potential. Most importantly, we emphasize the optimal target combinations and design strategies for EGFR dual-target inhibitors and provide some perspectives on new challenges and future directions in this field.

Colorectal liver metastasis: molecular mechanism and interventional therapy

Colorectal cancer (CRC) is one of the most frequently occurring malignancy tumors with a high morbidity additionally, CRC patients may develop liver metastasis, which is the major cause of death. Despite significant advances in diagnostic and therapeutic techniques, the survival rate of colorectal liver metastasis (CRLM) patients remains very low. CRLM, as a complex cascade reaction process involving multiple factors and procedures, has complex and diverse molecular mechanisms. In this review, we summarize the mechanisms/pathophysiology, diagnosis, treatment of CRLM. We also focus on an overview of the recent advances in understanding the molecular basis of CRLM with a special emphasis on tumor microenvironment and promise of newer targeted therapies for CRLM, further improving the prognosis of CRLM patients.

Selective and Nongenetic Peroxidase Tag of Membrane Protein: a Nucleic Acid Tool for Proximity Labeling

The protein nanoenvironment on the plasma membrane is intimately linked to cellular biological functions. Elucidation of the protein nanoenvironment contributes to understanding the pathological mechanism and discovery of disease biomarkers. However, methods enabling characterization of the protein nanoenvironment in the endogenous biological environment have been rarely developed. Toward this end, we created a nucleic acid tool called Apt-Gq/h for proximity labeling to decipher the endogenous protein nanoenvironment. Here, the aptamer acts as an anchor for binding the protein of interest (POI). The G-quadruplex/hemin complex induces proximity labeling of POI via catalyzing the conversion of inert small-molecule substrates into short-lived reactive species. The labeled proteins enable the subsequent affinity-based enrichment and proteomic analysis. We first characterized Apt-Gq/h-mediated POI labeling in vitro and tested its utility by interrogating the protein nanoenvironment of POI in living cells. Taking advantage of the nongenetic, multiple reaction sites, and rapid proximity labeling, Apt-Gq/h was further utilized to imaging the cell-cell connection and amplification detection of biomarkers in living cells and tissue sections. We believe that Apt-Gq/h will be a potential tool for basic science and clinical applications.

Chemosensitization of HT29 and HT29-5FU Cell Lines by a Combination of a Multi-Tyrosine Kinase Inhibitor and 5FU Downregulates ABCC1 and Inhibits PIK3CA in Light of Their Importance in Saudi Colorectal Cancer

Colorectal cancer (CRC) remains one of the main causes of death worldwide and in Saudi Arabia. The toxicity and the development of resistance against 5 fluorouracil 5FU pose increasing therapeutic difficulties, which necessitates the development of personalized drugs and drug combinations. Objectives: First, to determine the most important kinases and kinase pathways, and the amount of ABC transporters and KRAS in samples taken from Saudi CRC patients. Second, to investigate the chemosensitizing effect of LY294002 and HAA₂₀₂₀ and their combinations with 5FU on HT29, HT29-5FU, HCT116, and HCT116-5FU CRC cells, their effect on the three ABC transporters, cell cycle, and apoptosis, in light of the important kinase pathways resulting from the first part of this study. Methods: The PamChip^® peptide micro-array profiling was used to determine the level of kinase and targets in the Saudi CRC samples. Next, RT-PCR, MTT cytotoxicity, Western blotting, perturbation of cell cycle, annexin V, and immunofluorescence assays were used to investigate the effect on CRC, MRC5, and HUVEC cells. Results: The kinase activity profiling highlighted the importance of the PI3K/AKT, MAPK, and the growth factors pathways in the Saudi CRC samples. PIK3CA was the most overexpressed, and it was associated with increased level of mutated KRAS and the three ABC transporters, especially ABCC1 in the Saudi samples. Next, combining HAA₂₀₂₀ with 5FU exhibited the best synergistic and resistance-reversal effect in the four CRC cells, and the highest selectivity indices compared to MRC5 and HUVEC normal cells. Additionally, HAA₂₀₂₀ with 5FU exerted significant inhibition of ABCC1 in the four CRC cells, and inhibition of PIK3CA/AKT/MAPK7/ERK in HT29 and HT29-5FU cells. The combination also inhibited EGFR, increased the preG₁/S cell cycle phases, apoptosis, and caspase 8 in HT29 cells, while it increased the G₁ phase, p21/p27, and apoptosis in HT29-5FU cells. Conclusion: We have combined the PamChip kinase profiling of Saudi CRC samples with in vitro drug combination studies in four CRC cells, highlighting the importance of targeting PIK3CA and ABCC1 for Saudi CRC patients, especially given that the overexpression of PIK3CA mutations was previously linked with the lack of activity for the anti-EGFRs as first line treatment for CRC patients. The combination of HAA₂₀₂₀ and 5FU has selectively sensitized the four CRC cells to 5FU and could be further studied.

Blocking c-MET/ERBB1 Axis Prevents Brain Metastasis in ERBB2+ Breast Cancer

Simple Summary

Targeted monotherapies are ineffective in the treatment of brain metastasis of ERBB2⁺ breast cancer (BC) underscoring the need for combination therapies. The lack of robust preclinical models has further hampered the assessment of treatment modalities. We report here a clinically relevant orthotopic mouse model of ERBB2⁺ BC that spontaneously metastasizes to brain and demonstrates that targeting the c-MET/ERBB1 axis with a combination of cabozantinib and neratinib decreases primary tumor growth and prevents brain metastasis in ERBB2⁺ BC.

Abstract

Brain metastasis (BrM) remains a significant cause of cancer-related mortality in epidermal growth factor receptor 2-positive (ERBB2⁺) breast cancer (BC) patients. We proposed here that a combination treatment of irreversible tyrosine kinase inhibitor neratinib (NER) and the c-MET inhibitor cabozantinib (CBZ) could prevent brain metastasis. To address this, we first tested the combination treatment of NER and CBZ in the brain-seeking ERBB2⁺ cell lines SKBrM3 and JIMT-1-BR3, and in ERBB2⁺ organoids that expressed the c-MET/ERBB1 axis. Next, we developed and characterized an orthotopic mouse model of spontaneous BrM and evaluated the therapeutic effect of CBZ and NER in vivo. The combination treatment of NER and CBZ significantly inhibited proliferation and migration in ERBB2⁺ cell lines and reduced the organoid growth in vitro. Mechanistically, the combination treatment of NER and CBZ substantially inhibited ERK activation downstream of the c-MET/ERBB1 axis. Orthotopically implanted SKBrM3⁺ cells formed primary tumor in the mammary fat pad and spontaneously metastasized to the brain and other distant organs. Combination treatment with NER and CBZ inhibited primary tumor growth and predominantly prevented BrM. In conclusion, the orthotopic model of spontaneous BrM is clinically relevant, and the combination therapy of NER and CBZ might be a useful approach to prevent BrM in BC.

Design and Evaluation of PEGylated Liposomal Formulation of a Novel Multikinase Inhibitor for Enhanced Chemosensitivity and Inhibition of Metastatic Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) has one of the highest mortality rates among cancers. Chemotherapy is the standard first-line treatment, but only modest survival benefits are observed. With the advent of targeted therapies, epidermal growth factor receptor (EGFR) has been acknowledged as a prospective target in PDAC since it is overexpressed in up to 60% of cases. Similarly, the tyrosine-protein kinase Met (cMET) is also overexpressed in PDAC (27-60%) and is a prognostic marker for poor survival. Interestingly, EGFR and cMET share some common signaling pathways including PI3K/Akt and MAPK pathways. Small molecule inhibitors or bispecific antibodies that can target both EGFR and cMET are therefore emerging as novel options for cancer therapy. We previously developed a dual EGFR and cMET inhibitor (N19) that was able to inhibit tumor growth in nonsmall cell lung cancer models resistant to EGFR tyrosine kinase inhibitors (TKI). Here, we report the development of a novel liposomal formulation of N19 (LN19) and showed significant growth inhibition and increased sensitivity toward gemcitabine in the pancreatic adenocarcinoma orthotopic xenograft model. Taken together, our results suggest that LN19 can be valued as an effective combination therapy with conventional chemotherapy such as gemcitabine for PDAC patients.

The potential therapeutic and prognostic impacts of the c-MET/HGF signaling pathway in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer and a common cause of cancer-related mortality globally. In spite of the improvements in the early diagnosis of CRC, approximately one-third of patients develop metastasis and then have a very poor survival rate. The mesenchymal-epithelial transition factor (c-MET) is a tyrosine kinase cell surface receptor activated by hepatocyte growth factor (HGF). Activation of c-MET/HGF signaling pathway regulates a variety of biological processes including cell motility, cell proliferation, angiogenesis, the epithelial-to-mesenchymal transition, and the development and progression of cancer cells. Recent studies have suggested that the c-MET/HGF signaling pathway is involved in the carcinogenesis of CRC. In this review, we summarize the main findings of recent studies investigating the role of c-MET/HGF signaling pathway in CRC and the potential of the c-MET/HGF signaling pathways in the diagnosis and treatment of CRC. © 2019 IUBMB Life, 2019.

Efficacy of targeted liposomes and nanocochleates containing imatinib plus dexketoprofen against fibrosarcoma

The main challenges in treating cancer using chemotherapeutics are insufficient dose at the target site and the development of drug resistance, while higher doses can induce side effects by damaging nontarget tissues. Combinatorial drug therapy may overcome these limitations by permitting lower doses and more specific targeting, thereby mitigating drug resistance and nontarget side effects. Recent reports indicate that nonsteroidal anti-inflammatory drugs (NSAIDs) have anticancer potential and can be used together with conventional chemotherapeutics to improve efficacy and safety. In the present study, imatinib mesylate and dexketoprofen trometamol were selected as model drugs to develop targeted surface-modified liposome and nanocochleate formulations for fibrosarcoma treatment. The physicochemical properties and in vitro efficacy of various formulations were evaluated by measurement of particle size distribution, polydispersity index, zeta potential, encapsulation efficiency, diffusion through Caco-2 cells, and toxicity in culture. Selected formulations were then evaluated in fibrosarcoma-bearing model mice by histopathological observations and tyrosine kinase receptor inhibition assays. The most effective formulation on the fibrosarcoma model was a PEGylated nanocochleate formulation. These findings provide a foundation for developing more effective formulations and chemotherapeutic strategies for the treatment of fibrosarcoma and other types of cancer.

Disruption of IGF‑1R signaling by a novel quinazoline derivative, HMJ‑30, inhibits invasiveness and reverses epithelial-mesenchymal transition in osteosarcoma U‑2 OS cells

Osteosarcoma is the most common primary malignancy of the bone and is characterized by local invasion and distant metastasis. Over the past 20 years, long-term outcomes have reached a plateau even with aggressive therapy. Overexpression of insulin-like growth factor 1 receptor (IGF‑1R) is associated with tumor proliferation, invasion and migration in osteosarcoma. In the present study, our group developed a novel quinazoline derivative, 6-fluoro‑2-(3-fluorophenyl)-4-(cyanoanilino)quinazoline (HMJ‑30), in order to disrupt IGF‑1R signaling and tumor invasiveness in osteosarcoma U‑2 OS cells. Molecular modeling, immune-precipitation, western blotting and phosphorylated protein kinase sandwich ELISA assays were used to confirm this hypothesis. The results demonstrated that HMJ‑30 selectively targeted the ATP-binding site of IGF‑1R and inhibited its downstream phosphoinositide 3-kinase/protein kinase B, Ras/mitogen-activated protein kinase, and IκK/nuclear factor-κB signaling pathways in U‑2 OS cells. HMJ‑30 inhibited U‑2 OS cell invasion and migration and downregulated protein levels and activities of matrix metalloproteinase (MMP)‑2 and MMP-9. An increase in protein levels of tissue inhibitor of metalloproteinase (TIMP)‑1 and TIMP‑2 was also observed. Furthermore, HMJ‑30 caused U‑2 OS cells to aggregate and form tight clusters, and these cells were flattened, less elongated and displayed cobblestone-like shapes. There was an increase in epithelial markers and a decrease in mesenchymal markers, indicating that the cells underwent the reverse epithelial-mesenchymal transition (EMT) process. Overall, these results demonstrated the potential molecular mechanisms underlying the effects of HMJ‑30 on invasiveness and EMT in U‑2 OS cells, suggesting that this compound deserves further investigation as a potential anti-osteosarcoma drug.

A randomized, placebo-controlled, phase 1/2 study of tivantinib (ARQ 197) in combination with irinotecan and cetuximab in patients with metastatic colorectal cancer with wild-type KRAS who have received first-line systemic therapy

Cetuximab in combination with an irinotecan-containing regimen is a standard treatment in patients with KRAS wild-type (KRAS WT), metastatic colorectal cancer (mCRC). We investigated the addition of the oral MET inhibitor tivantinib to cetuximab + irinotecan (CETIRI) based on preclinical evidence that activation of the MET pathway may confer resistance to anti-EGFR therapy. Previously treated patients with KRAS WT advanced or mCRC were enrolled. The phase 1, open-label 3 + 3, dose-escalation study evaluated the safety and maximally tolerated dose of tivantinib plus CETIRI. The phase 2, randomized, double-blinded, placebo-controlled study of biweekly CETIRI plus tivantinib or placebo was restricted to patients who had received only one prior line of chemotherapy. The phase 2 primary endpoint was progression-free survival (PFS). The recommended phase 2 dose was tivantinib (360 mg/m(2) twice daily) with biweekly cetuximab (500 mg/m(2)) and irinotecan (180 mg/m(2)). Among 117 patients evaluable for phase 2 analysis, no statistically significant PFS difference was observed: 8.3 months on tivantinib vs. 7.3 months on placebo (HR, 0.85; 95% confidence interval, 0.55-1.33; P = 0.38). Subgroup analyses trended in favor of tivantinib in patients with MET-High tumors by immunohistochemistry, PTEN-Low tumors, or those pretreated with oxaliplatin, but subgroups were too small to draw conclusions. Neutropenia, diarrhea, nausea and rash were the most frequent severe adverse events in tivantinib-treated patients. The combination of tivantinib and CETIRI was well tolerated but did not significantly improve PFS in previously treated KRAS WT mCRC. Tivantinib may be more active in specific subgroups.

Recombinant Lactococcus lactis NZ9000 secretes a bioactive kisspeptin that inhibits proliferation and migration of human colon carcinoma HT-29 cells

Background

Proteinaceous bioactive substances and pharmaceuticals are most conveniently administered orally. However, the facing problems are the side effects of proteolytic degradation and denaturation in the gastrointestinal tract. In recent years, lactic acid bacteria (LAB) have been verified to be a promising delivery vector for susceptible functional proteins and drugs. KiSS-1 peptide, a cancer suppressor, plays a critical role in inhibiting cancer metastasis and its activity has been confirmed by direct administration. However, whether this peptide can be functionally expressed in LAB and exert activity on cancer cells, thus providing a potential alternative administration manner in the future, has not been demonstrated.

Results

A recombinant Lactococcus lactis strain NZ9000-401-kiss1 harboring a plasmid containing the gene of the tumor metastasis-inhibiting peptide KiSS1 was constructed. After optimization of the nisin induction conditions, the recombinant strain efficiently secreted KiSS1 with a maximum detectable amount of 27.9 μg/ml in Dulbecco’s Modified Eagle medium. The 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide and would healing assays, respectively, indicated that the secreted KiSS1 peptide remarkably inhibited HT-29 cell proliferation and migration. Furthermore, the expressed KiSS1 was shown to induce HT-29 cell morphological changes, apoptosis and reduce the expression of matrix metalloproteinase 9 (MMP-9) at both mRNA and protein levels.

Conclusions

A recombinant L. lactis NZ9000-401-kiss1 successfully expressing the human kiss1 was constructed. The secreted KiSS1 peptide inhibited human HT-29 cells’ proliferation and migration probably by invoking, or mediating the cell-apoptosis pathway and by down regulating MMP-9 expression, respectively. Our results suggest that L. lactis is an ideal cell factory for secretory expression of tumor metastasis-inhibiting peptide KiSS1, and the KiSS1-producing L. lactis strain may serve as a new tool for cancer therapy in the future.

Quercetin metabolites inhibit MMP-2 expression in A549 lung cancer cells by PPAR-γ associated mechanisms

Our previous study demonstrated that quercetin-metabolite-enriched plasma (QP) but not quercetin itself upregulates peroxisome proliferator-activated receptor gamma (PPAR-γ) expression to induce G2/M arrest in A549 cells. In the present study, we incubated A549 cells with QP as well as quercetin-3-glucuronide (Q3G) and quercetin-3'-sulfate (Q3'S), two major metabolites of quercetin, to investigate the effects of quercetin metabolites on cell invasion and migration, the possible mechanisms and the role of PPAR-γ. We also compared the effects of QP with those of quercetin and troglitazone (TGZ), a PPAR-γ ligand. The results showed that QP significantly suppressed cell invasion and migration, as well as matrix metalloproteinases (MMPs)-2 activity and expression in a dose-dependent manner. The effects of 10% QP on those parameters were similar to those of 10μM quercetin and 20μM TGZ. However, QP and TGZ rather than quercetin itself increased the expressions of nm23-H1 and tissue inhibitor of metalloproteinase (TIMP-2). Furthermore, we demonstrated that Q3G and Q3'S also inhibited the protein expression of MMP-2. GW9662, a PPAR-γ antagonist, significantly diminished such an effect of Q3G and Q3'S. Silencing PPAR-γ expression in A549 cells also significantly diminished the suppression effect of Q3G and Q3'S on MMP-2 expression. Taken together, our study demonstrated that QP inhibited cell invasion and migration through nm23-H1/TIMP-2/MMP-2 associated mechanisms. The upregulation of PPAR-γ by quercetin metabolites such as Q3G and Q3'S could play an important role in the effects of QP.

Hyperphosphorylation of ribosomal protein S6 predicts unfavorable clinical survival in non-small cell lung cancer

Background

Ribosomal protein S6 (rpS6), a component of the 40S ribosomal subunit, is involved in multiple cellular bioactivities. However, its clinicopathological significance in non-small cell lung cancer (NSCLC) is poorly understood.

Methods

Expressions of total rpS6 (t-rpS6) and phosphorylated rpS6 (Ser235/236, p-rpS6) were detected immunohistochemically in 316 NSCLC tissues and 82 adjacent controls, followed by statistical evaluation of the relationship between proteins expressions and patients’ survivals to identify their prognostic values. Cytological experiments with overexpressing or silencing rpS6 by lentivirus in human bronchial epithelial (HBE) and NSCLC cell lines were performed to explore potential mechanisms by which rpS6 affects the clinical development of NSCLC. Additionally, specific RNA interference for Akt1, Akt2, Akt3, Akt inhibitor and subsequent cellular bioactivity tests were employed as well to investigate the upstream regulation of rpS6.

Results

Positive rates of t-rpS6 and p-rpS6 were both significantly increased in NSCLC tissues, compared with controls (82.91 vs 62.20 % for t-rpS6; 52.22 vs 21.95 % for p-rpS6; both P < 0.001). However, only hyperphosphorylation of rpS6, expressed as either elevated p-rpS6 alone or the ratio of p-rpS6 to t-rpS6 (p-rpS6/t-rpS6) no less than 0.67, was greatly associated with the unfavorable survival of NSCLC patients, especially for cases at stage I (all P < 0.001). The independent adverse prognostic value of hyperphosphorylated rpS6 was confirmed by multivariate Cox regression analysis (hazard ratios for elevated p-rpS6 alone and p-rpS6/t-rpS6 no less than 0.67 were 2.403, 4.311 respectively, both P < 0.001). Overexpression or knockdown of rpS6, along with parallel alterations of p-rpS6, led to increased or decreased cells proliferations respectively, which were dependent on redistributions of cell cycles (all P < 0.05). Cells migration and invasion also changed with rpS6 interference (all P < 0.05). Furthermore, upstream overexpression or knockdown of Akt2 or Akt2 phosphorylation inhibition, rather than Akt1 or Akt3, resulted in striking hyperphosphorylation or dephosphorylation of mTOR, p70S6K and rpS6 (all P < 0.05), without any change in total proteins expressions. Further tests showed markedly accompanied variation of cells proliferation, cell cycle distribution and invasion (all P < 0.05).

Conclusion

Hyperphosphorylation of rpS6, probably regulated by the Akt2/mTOR/p70S6K signaling pathway, is closely relevant to the progression of NSCLC and it might be served as a promising therapeutic target for NSCLC treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0239-1) contains supplementary material, which is available to authorized users.

Molecular markers predictive of chemotherapy response in colorectal cancer

Recognition of the molecular heterogeneity of colorectal cancer (CRC) has led to the classification of CRC based on a variety of clinical and molecular characteristics. Although the clinical significance of the majority of these molecular alterations is still being ascertained, it is widely anticipated that these characteristics will improve the accuracy of our ability to determine the prognosis and therapeutic response of CRC patients. A few of these markers, such as microsatellite instability and the CpG island methylator phenotype (CIMP), show promise as predictive markers for cytotoxic chemotherapy. KRAS is a validated biomarker for epidermal growth factor receptor (EGFR)-targeted therapy, while NRAS and PI3KCA are evolving markers for targeted therapies. Multiple new actionable drug targets and potential response biomarkers are being identified on a regular basis, but most are not ready for clinical use at this time. This review focuses on key molecular features of CRCs and the application of these molecular alterations as predictive biomarkers for CRC.

YKL-40/c-Met expression in rectal cancer biopsies predicts tumor regression following neoadjuvant chemoradiotherapy: a multi-institutional study

BACKGROUND

Neoadjuvant chemo-radiotherapy (CRT) followed by surgical resection is the standard treatment for locally advanced rectal cancer, although complete tumor pathological regression is achieved in only up to 30% of cases. A clinicopathological and molecular predictive stratification of patients with advanced rectal cancer is still lacking. Here, c-Met and YKL-40 have been studied as putative predictors of CRT response in rectal cancer, due to their reported involvement in chemoradioresistance in various solid tumors.

MATERIAL AND METHODS

A multicentric study was designed to assess the role of c-Met and YKL-40 expression in predicting chemoradioresistance and to correlate clinical and pathological features with CRT response. Immunohistochemistry and fluorescent in situ hybridization for c-Met were performed on 81 rectal cancer biopsies from patients with locally advanced rectal adenocarcinoma. All patients underwent standard (50.4 gy in 28 fractions + concurrent capecitabine 825 mg/m2) neoadjuvant CRT or the XELOXART protocol. CRT response was documented on surgical resection specimens and recorded as tumor regression grade (TRG) according to the Mandard criteria.

RESULTS

A significant correlation between c-Met and YKL-40 expression was observed (R = 0.43). The expressions of c-Met and YKL-40 were both significantly associated with a lack of complete response (86% and 87% of c-Met and YKL-40 positive cases, p< 0.01 and p = 0.006, respectively). Thirty of the 32 biopsies co-expressing both markers had partial or absent tumor response (TRG 2-5), strengthening their positive predictive value (94%). The exclusive predictive role of YKL-40 and c-Met was confirmed using a multivariate analysis (p = 0.004 and p = 0.007 for YKL-40 and c-Met, respectively). TRG was the sole morphological parameter associated with poor outcome.

CONCLUSION

c-Met and YKL-40 expression is a reliable predictor of partial/absent response to neoadjuvant CRT in rectal cancer. Targeted therapy protocols could take advantage of prior evaluations of c-MET and YKL-40 expression levels to increase therapeutic efficacy.

Src is a novel potential off-target of RXR agonists, 9-cis-UAB30 and Targretin, in human breast cancer cells

9-cis-UAB30 (UAB30) and Targretin are well-known retinoid X receptor (RXR) agonists. They were highly effective in decreasing the incidence of methylnitrosourea (MNU)-induced mammary cancers. However, whether the anti-mammary cancer effects of UAB30 or Targretin originate from the activation of RXR is unclear. In the present study, we hypothesized that UAB30 and Targretin not only affect RXR, but likely influence one or more off-target proteins. Virtual screening results suggest that Src is a potential target for UAB30 and Targretin that regulates extracellular matrix (ECM) molecules and cell motility and invasiveness. In vitro kinase assay data revealed that UAB30 or Targretin interacted with Src and attenuated its kinase activity. We found that UAB30 or Targretin substantially inhibited invasiveness and migration of MCF-7 and SK-BR-3 human breast cancer cells. We examined the effects of UAB30 and Targretin on the expression of matrix metalloproteinases (MMP)-9, which are known to play an essential role in tumor invasion. We show that activity and expression of MMP-9 were decreased by UAB30 or Targretin. Western blot data showed that UAB30 or Targretin decreased AKT and its substrate molecule p70(s6k), which are downstream of Src in MCF-7 and SK-BR-3 cells. Moreover, knocking down the expression of Src effectively reduced the sensitivity of SK-BR-3 cells to the inhibitory effects of UAB30 and Targretin on invasiveness. Taken together, our results demonstrate that UAB30 and Targretin each inhibit invasion and migration by targeting Src in human breast cancer cells.

De Novo proteome analysis of genetically modified tumor cells by a metabolic labeling/azide-alkyne cycloaddition approach

Activin receptor type II (ACVR2) is a member of the transforming growth factor type II receptor family and controls cell growth and differentiation, thereby acting as a tumor suppressor. ACVR2 inactivation is known to drive colorectal tumorigenesis. We used an ACVR2-deficient microsatellite unstable colon cancer cell line (HCT116) to set up a novel experimental design for comprehensive analysis of proteomic changes associated with such functional loss of a tumor suppressor. To this end we combined two existing technologies. First, the ACVR2 gene was reconstituted in an ACVR2-deficient colorectal cancer (CRC) cell line by means of recombinase-mediated cassette exchange, resulting in the generation of an inducible expression system that allowed the regulation of ACVR2 gene expression in a doxycycline-dependent manner. Functional expression in the induced cells was explicitly proven. Second, we used the methionine analog azidohomoalanine for metabolic labeling of newly synthesized proteins in our cell line model. Labeled proteins were tagged with biotin via a Click-iT chemistry approach enabling specific extraction of labeled proteins by streptavidin-coated beads. Tryptic on-bead digestion of captured proteins and subsequent ultra-high-performance LC coupled to LTQ Orbitrap XL mass spectrometry identified 513 proteins, with 25 of them differentially expressed between ACVR2-deficient and -proficient cells. Among these, several candidates that had already been linked to colorectal cancer or were known to play a key role in cell growth or apoptosis control were identified, proving the utility of the presented experimental approach. In principle, this strategy can be adapted to analyze any gene of interest and its effect on the cellular de novo proteome.

Discovery and Biological Evaluation of Novel Dual EGFR/c-Met Inhibitors

Activating mutations in the epidermal growth factor receptor (EGFR) have been identified in a subset of non-small cell lung cancer (NSCLC), which is one of the leading cancer types worldwide. Application of EGFR tyrosine kinase inhibitors leads to acquired resistance by secondary EGFR mutations or by amplification of the hepatocyte growth factor receptor (c-Met) gene. Although several EGFR and c-Met inhibitors have been reported, potent dual EGFR/c-Met inhibitors, which can overcome this latter resistance mechanism, have hitherto not been published and have not reached clinical trials. In the present study we have identified dual EGFR/c-Met inhibitors and designed novel N-[4-(quinolin-4-yloxy)-phenyl]-biarylsulfonamide derivatives, which inhibit the c-Met receptor and both the wild-type and the activating mutant EGFR kinases in nanomolar range. We have demonstrated by Western blot analysis that compound 10 inhibits EGFR and c-Met phosphorylation at cellular level and effectively inhibits viability of the NSCLC cell lines.

Expression of c-Met protein in gastrointestinal tumors: Recent research progress

There is a close relationship between HGF/c-Met and many human cancers. The activation and overexpression of HGF/c-Met can cause the growth, invasion and metastasis of breast cancer, ovarian cancer, endometrial cancer, lung cancer, and digestive system tumors. Since c-Met plays an important role in the growth and metastasis of tumors, targeting the HGF/c-Met pathway has become a hotspot for anti-cancer research. Currently, there have been many reports about c-Met expression in digestive tumors. In this paper we try to elaborate the latest progress in research related to c-Met expression in digestive tumors, with an aim to help clinicians gain a systematic understanding of this issue.