The impact of R213 mutation on p53-mediated p21 activity

Effects of aspirin on colon cancer using quantitative proteomic analysis

Background

Colon cancer is one of the most prevalent digestive cancers worldwide. Results of epidemiological, experimental, and clinical studies suggest that aspirin inhibits the development of colon cancer. This study aimed to systematically elucidate the molecular mechanisms by which aspirin prevents colon carcinogenesis.

Methods

We determined the global protein expression profiles of colorectal cancer and aspirin-treated cells using quantitative proteomic analysis. We analyzed the proteomic results using bioinformatics (including differential proteins, protein annotation, Kyoto Encyclopedia of Genes and Genomes [KEGG] pathways, and protein-protein interaction [PPI] network). The viability of the colon cancer cell line and HT29 ​cells treated with aspirin was determined using the cell counting kit-8 assay. The differentially expressed proteins, such as p53 and cyclin-dependent kinase 1 (CDK1), were quantified using real-time polymerase chain reaction (PCR) and Western blotting. We measured cell cycle distribution and apoptosis in HT29 ​cells exposed to aspirin using fluorescence-activated cell sorting (FACS).

Results

We found that 552 proteins were significantly dysregulated, of which 208 and 334 were upregulated and downregulated, respectively, in colon cancer cells exposed to 10 ​mmol/L of aspirin (95% confidence interval [CI]: -1.269 to -0.106, P ​< ​0.05). Further gene enrichment analysis revealed that cell cycle-related proteins, such as p53 and CDK1, were significantly differentially expressed. Proteomic analysis showed that after 24 ​h of aspirin exposure, the level of p53 increased by 2.52-fold and CDK1 was downregulated to half that of the controls in HT29 ​cells (95% CI: -0.619 to -0.364, P ​< ​0.05). Real-time PCR and Western blotting results showed that p53 was upregulated (95%CI: -3.088 to -1.912, P ​< ​0.001) and CDK1 was significantly downregulated after aspirin exposure in colon cancer cells (95% CI: 0.576 to 1.045, P ​< ​0.05). We observed that aspirin promoted G1/S cell cycle arrest in HT29 ​cells. We confirmed that aspirin induces apoptosis in human HT29 colon cancer cells in a concentration-dependent manner.

Conclusions

These results indicate that aspirin induces G1 arrest and apoptosis in colorectal cancer cells via the p53-CDK1 pathway. Aspirin may be a promising drug candidate for colon cancer prevention.

P2Y11/IL-1 receptor crosstalk controls macrophage inflammation: a novel target for anti-inflammatory strategies?

Although first cloning of the human ATP receptor P2Y11 was successful 25 years ago, the exact downstream signaling pathways of P2Y11 receptor, which can couple to Gq and Gs proteins, have remained unclear. Especially the lack of rodent models as well as the limited availability of antibodies and pharmacological tools have hampered examination of P2Y11 expression and function. Many meaningful observations related to P2Y11 have been made in primary immune cells, indicating that P2Y11 receptors are important regulators of inflammation and cell migration, also by controlling mitochondrial activity. Our recent studies have shown that P2Y11 is upregulated during macrophage development and activates signaling through IL-1 receptor, which is well known for its ability to direct inflammatory and migratory processes. This review summarizes the results of the first transcriptomic and secretomic analyses of both, ectopic and native P2Y11 receptors, and discusses how P2Y11 crosstalk with the IL-1 receptor may govern anti-inflammatory and pro-angiogenic processes in human M2 macrophages.

Hidden electrostatic energy contributions define dynamic allosteric communications within p53 during molecular recognition

Molecular recognition is fundamental to transcription regulation. As a transcription factor, the tumor suppressor p53 has to recognize either specific DNA sequences or repressor protein partners. However, the molecular mechanism underlying the p53 conformational switch from the DNA-bound to repressor-bound states is not fully characterized. The highly charged nature of these interacting molecules prompted us to explore the nonbonded energy contributions behind molecular recognition of either a DNA or the repressor protein iASPP by p53 DNA binding domain (p53DBD), using molecular dynamics simulation followed by rigorous analyses of energy terms. Our results illuminate the allosteric pathway by which iASPP binding to p53 diminishes binding affinity between p53 and DNA. Even though the p53DBD uses a common framework of residues for recognizing both DNA and iASPP, a comparison of the electrostatics in the two p53DBD complexes revealed significant differences in residue-wise contributions to the electrostatic energy. We found that an electrostatic allosteric communication path exists in the presence of both substrates. It consists of evolutionarily conserved residues, from residue K120 of the binding loop L1 to a distal residue R213 of p53DBD. K120 is near the DNA in the p53DBD-DNA complex, whereas iASPP binding moves it away from its DNA binding position in the p53DBD-iASPP complex. The "energy hubs" (the residues show a higher degree of connectivity with other residues in the electrostatic networks) determined from the electrostatic network analysis established that this conformational change in K120 completely rewires the electrostatic network from K120 to R213, thereby impeding DNA binding. Furthermore, we found shifting populations of hydrogen bonds and salt bridges reduce pairwise electrostatic energies within p53DBD in its DNA-bound state.

Arginine Methyltransferase PRMT1 Regulates p53 Activity in Breast Cancer

The protein p53 is one of the most important tumor suppressors, responding to a variety of stress signals. Mutations in p53 occur in about half of human cancer cases, and dysregulation of the p53 function by epigenetic modifiers and modifications is prevalent in a large proportion of the remainder. PRMT1 is the main enzyme responsible for the generation of asymmetric-dimethylarginine, whose upregulation or aberrant splicing has been observed in many types of malignancies. Here, we demonstrate that p53 function is regulated by PRMT1 in breast cancer cells. PRMT1 knockdown activated the p53 signal pathway and induced cell growth-arrest and senescence. PRMT1 could directly bind to p53 and inhibit the transcriptional activity of p53 in an enzymatically dependent manner, resulting in a decrease in the expression levels of several key downstream targets of the p53 pathway. We were able to detect p53 asymmetric-dimethylarginine signals in breast cancer cells and breast cancer tissues from patients, and the signals could be significantly weakened by silencing of PRMT1 with shRNA, or inhibiting PRMT1 activity with a specific inhibitor. Furthermore, PRMT1 inhibitors significantly impeded cell growth and promoted cellular senescence in breast cancer cells and primary tumor cells. These results indicate an important role of PRMT1 in the regulation of p53 function in breast tumorigenesis.

Nkx2.5 Functions as a Conditional Tumor Suppressor Gene in Colorectal Cancer Cells via Acting as a Transcriptional Coactivator in p53-Mediated p21 Expression

NK2 homeobox 5 (Nkx2.5), a homeobox-containing transcription factor, is associated with a spectrum of congenital heart diseases. Recently, Nkx2.5 was also found to be differentially expressed in several kinds of tumors. In colorectal cancer (CRC) tissue and cells, hypermethylation of Nkx2.5 was observed. However, the roles of Nkx2.5 in CRC cells have not been fully elucidated. In the present study, we assessed the relationship between Nkx2.5 and CRC by analyzing the expression pattern of Nkx2.5 in CRC samples and the adjacent normal colonic mucosa (NCM) samples, as well as in CRC cell lines. We found higher expression of Nkx2.5 in CRC compared with NCM samples. CRC cell lines with poorer differentiation also had higher expression of Nkx2.5. Although this expression pattern makes Nkx2.5 seem like an oncogene, in vitro and in vivo tumor suppressive effects of Nkx2.5 were detected in HCT116 cells by establishing Nkx2.5-overexpressed CRC cells. However, Nkx2.5 overexpression was incapacitated in SW480 cells. To further assess the mechanism, different expression levels and mutational status of p53 were observed in HCT116 and SW480 cells. The expression of p21^WAF1/CIP1, a downstream antitumor effector of p53, in CRC cells depends on both expression level and mutational status of p53. Overexpressed Nkx2.5 could elevate the expression of p21^WAF1/CIP1 only in CRC cells with wild-type p53 (HCT116), rather than in CRC cells with mutated p53 (SW480). Mechanistically, Nkx2.5 could interact with p53 and increase the transcription of p21^WAF1/CIP1 without affecting the expression of p53. In conclusion, our findings demonstrate that Nkx2.5 could act as a conditional tumor suppressor gene in CRC cells with respect to the mutational status of p53. The tumor suppressive effect of Nkx2.5 could be mediated by its role as a transcriptional coactivator in wild-type p53-mediated p21^WAF1/CIP1 expression.

Drug design targeting active posttranslational modification protein isoforms

Modern drug design aims to discover novel lead compounds with attractable chemical profiles to enable further exploration of the intersection of chemical space and biological space. Identification of small molecules with good ligand efficiency, high activity, and selectivity is crucial toward developing effective and safe drugs. However, the intersection is one of the most challenging tasks in the pharmaceutical industry, as chemical space is almost infinity and continuous, whereas the biological space is very limited and discrete. This bottleneck potentially limits the discovery of molecules with desirable properties for lead optimization. Herein, we present a new direction leveraging posttranslational modification (PTM) protein isoforms target space to inspire drug design termed as "Post-translational Modification Inspired Drug Design (PTMI-DD)." PTMI-DD aims to extend the intersections of chemical space and biological space. We further rationalized and highlighted the importance of PTM protein isoforms and their roles in various diseases and biological functions. We then laid out a few directions to elaborate the PTMI-DD in drug design including discovering covalent binding inhibitors mimicking PTMs, targeting PTM protein isoforms with distinctive binding sites from that of wild-type counterpart, targeting protein-protein interactions involving PTMs, and hijacking protein degeneration by ubiquitination for PTM protein isoforms. These directions will lead to a significant expansion of the biological space and/or increase the tractability of compounds, primarily due to precisely targeting PTM protein isoforms or complexes which are highly relevant to biological functions. Importantly, this new avenue will further enrich the personalized treatment opportunity through precision medicine targeting PTM isoforms.

Rapha Myr®, a Blend of Sulforaphane and Myrosinase, Exerts Antitumor and Anoikis-Sensitizing Effects on Human Astrocytoma Cells Modulating Sirtuins and DNA Methylation

Brain and other nervous system cancers are the 10th leading cause of death worldwide. Genome instability, cell cycle deregulation, epigenetic mechanisms, cytoarchitecture disassembly, redox homeostasis as well as apoptosis are involved in carcinogenesis. A diet rich in fruits and vegetables is inversely related with the risk of developing cancer. Several studies report that cruciferous vegetables exhibited antiproliferative effects due to the multi-pharmacological functions of their secondary metabolites such as isothiocyanate sulforaphane deriving from the enzymatic hydrolysis of glucosinolates. We treated human astrocytoma 1321N1 cells for 24 h with different concentrations (0.5, 1.25 and 2.5% v/v) of sulforaphane plus active myrosinase (Rapha Myr®) aqueous extract (10 mg/mL). Cell viability, DNA fragmentation, PARP-1 and γH2AX expression were examined to evaluate genotoxic effects of the treatment. Cell cycle progression, p53 and p21 expression, apoptosis, cytoskeleton morphology and cell migration were also investigated. In addition, global DNA methylation, DNMT1 mRNA levels and nuclear/mitochondrial sirtuins were studied as epigenetic biomarkers. Rapha Myr® exhibited low antioxidant capability and exerted antiproliferative and genotoxic effects on 1321N1 cells by blocking the cell cycle, disarranging cytoskeleton structure and focal adhesions, decreasing the integrin α5 expression, renewing anoikis and modulating some important epigenetic pathways independently of the cellular p53 status. In addition, Rapha Myr® suppresses the expression of the oncogenic p53 mutant protein. These findings promote Rapha Myr® as a promising chemotherapeutic agent for integrated cancer therapy of human astrocytoma.

Nitric Oxide Donor DETA/NO Inhibits the Growth of Endometrial Cancer Cells by Upregulating the Expression of RASSF1 and CDKN1A

Nitric oxide (NO) is implicated in several biological processes, including cancer progression. At low concentrations, it promotes cell survival and tumor progression, and at high concentrations it causes apoptosis and cell death. Until now, the impact of NO donors has not been investigated on human endometrial tumors. Four cancer cell lines were exposed to different concentrations of DETA/NO for 24 to 120 h. The effects of DETA/NO on cell proliferation and invasion were determined utilizing MTS and Boyden chamber assays, respectively. The DETA/NO induced a dose and time-dependent reduction in cell viability by the activation of caspase-3 and cell cycle arrest at the G0/G1 phase that was associated with the attenuated expression of cyclin-D1 and D3. Furthermore, the reduction in the amount of CD133-expressing cancer stem-like cell subpopulation was observed following DETA/NO treatment of cells, which was associated with a decreased expression of stem cell markers and attenuation of cell invasiveness. To understand the mechanisms by which DETA/NO elicits anti-cancer effects, RNA sequencing (RNA-seq) was used to ascertain alterations in the transcriptomes of human endometrial cancer cells. RNA-seq analysis revealed that 14 of the top 21 differentially expressed genes were upregulated and seven were downregulated in endometrial cancer cells with DETA/NO. The genes that were upregulated in all four cell lines with DETA/NO were the tumor suppressors Ras association domain family 1 isoform A (RASSF1) and Cyclin-dependent kinase inhibitor 1A (CDKN1A). The expression patterns of these genes were confirmed by Western blotting. Taken together, the results provide the first evidence in support of the anti-cancer effects of DETA/NO in endometrial cancer.

CX-3543 Promotes Cell Apoptosis through Downregulation of CCAT1 in Colon Cancer Cells

Aim

Colon cancer-associated transcript-1 (CCAT1), located in the vicinity of transcription factor c-Myc, was first identified in colon cancer. A small-molecule compound CX3543 (Quarfloxin) selectively targeting Myc G-quadruplexes has entered phase II clinical trials for neuroendocrine carcinomas. The aim of the study was to explore the relationship between CX3543, CCAT1, and cell apoptosis in colon cancer cells.

Methods

Semiquantitative PCR was used to detect the relative expression of CCAT1 in colon cancer (CC) tissues and HT29 cell lines. Real-time PCR (RT-PCR) was also used to investigate the expression of CCAT1 and c-Myc after HT29 cells being treated by CX3543 for 24 h. Cell apoptosis assay and cell proliferation assay were conducted in HT29 cells after being treated by CX3543.

Results

The results showed that the expression of CCAT1 was remarkably increased in CC tissues and HT29 cells compared to controls. CX3543 treatment reduced the expression of c-Myc and CCAT1 and promoted cell apoptosis and inhibited cell proliferation. After the expression of CCAT1 was inhibited by sh-CCAT1 transfection, the cell apoptosis rate was higher than that of control group. After the cells were treated by CCAT1 overexpression plasmid transfection and CX3543, the cell apoptosis rate was lower than that of control group. In vivo results showed that CX3543 inhibited the xenograft tumor growth of rats through downregulation of CCAT1.

Conclusion

Our study demonstrated that CX3543 could inhibit the progression of colon cancer by downregulating CCAT1 expression and might be a potential drug for the treatment of colon cancer.

Effect of CCNB1 silencing on cell cycle, senescence, and apoptosis through the p53 signaling pathway in pancreatic cancer

Pancreatic cancer (PC) is a serious malignancy with high mortality and poor prognosis due to nonspecific incipient symptoms and early metastasis. Also, increasing evidence indicates that a panel of genes is newly identified in the pathogenesis of PC. As is a regulatory subunit, elevated cyclin B1 (CCNB1) expression has been detected in different cancers including PC. This study is designed to investigate the effects of CCNB1 silencing on cell cycle, senescence, and apoptosis through the p53 signaling pathway in PC. PC tissues and normal pancreatic tissues were collected. Cells were transfected and assigned into different groups. The expressions of CCNB1, p53, MDM2, Bax, caspase-9, caspase-3, and p21 in tissues and cells were detected by reverse transcription quantitative polymerase chain reaction and western blot analysis. β-Galactosidase staining, MTT assay, and flow cytometry were conducted to test cell senescence, proliferation, cell cycle, and apoptosis. PC tissues showed higher expressions of CCNB1 and MDM2 and lower expressions of Bax, caspase-9, caspase-3, and p21. Cells transfected with shCCNB1 had lower expressions of CCNB1 and MDM2, whereas higher expressions of Bax, caspase-9, caspase-3, p53, and p21. The shCCNB1 group had decreased proliferation and S-phase cell proportion and increased apoptosis, senescence, and G0/G1-phase cell proportion. The PFT-α group showed higher expressions of MDM2 and lower expressions of Bax, caspase-9, caspase-3, p53, and p21. The PFT-α group had increased proliferation and S-phase cell proportion and declined apoptosis, senescence, and G0/G1-phase cell proportion. CCNB1 silencing inhibits cell proliferation and promotes cell senescence via activation of the p53 signaling pathway in PC.

Protein arginine methylation: an emerging regulator of the cell cycle

Protein arginine methylation is a common post-translational modification where a methyl group is added onto arginine residues of a protein to alter detection by its binding partners or regulate its activity. It is known to be involved in many biological processes, such as regulation of signal transduction, transcription, facilitation of protein–protein interactions, RNA splicing and transport. The enzymes responsible for arginine methylation, protein arginine methyltransferases (PRMTs), have been shown to methylate or associate with important regulatory proteins of the cell cycle and DNA damage repair pathways, such as cyclin D1, p53, p21 and the retinoblastoma protein. Overexpression of PRMTs resulting in aberrant methylation patterns in cancers often correlates with poor recovery prognosis. This indicates that protein arginine methylation is also an important regulator of the cell cycle, and consequently a target for cancer regulation. The effect of protein arginine methylation on the cell cycle and how this emerging key player of cell cycle regulation may be used in therapeutic strategies for cancer are the focus of this review.

Specific up-regulation of p21 by a small active RNA sequence suppresses human colorectal cancer growth

The double stranded small active RNA (saRNA)- p21-saRNA-322 inhibits tumor growth by stimulating the p21 gene expression. We focused our research of p21-saRNA-322 on colorectal cancer because 1) p21 down-regulation is a signature abnormality of the cancer, and 2) colorectal cancer might be a suitable target for in situ p21-saRNA-322 delivery. The goal of the present study is to learn the activity of p21-saRNA-322 in colorectal cancer. Three human colorectal cancer cell lines, HCT-116, HCT-116 (p53–/−) and HT-29 were transfected with the p21-saRNA-322. The expression of P21 protein and p21 mRNA were measured using the Western blot and reverse transcriptase polymerase chain reaction (RT-PCR). The effect of p21-saRNA-322 on cancer cells was evaluated in vitro; and furthermore, a xenograft colorectal tumor mode in mice was established to estimate the tumor suppressing ability of p21-saRNA-322 in vivo. The results showed that in all three colorectal cancer cell lines, the expression of p21 mRNA and P21 protein were dramatically elevated after p21-saRNA-322 transfection. Transfection of p21-saRNA-322 caused apoptosis and cell cycle arrest at the G₀/G₁. Furthermore, anti-proliferation effect, reduction of colonies formation and cell senescence were observed in p21-saRNA-322 treated cells. Animal studies showed that p21-saRNA-322 treatment significantly inhibited the HT-29 tumor growth and facilitated p21 activation in vivo. These results indicated that, p21-saRNA-322-induceded up-regulation of p21 might be a promising therapeutic option for the treatment of colorectal cancer.

Role of citrullination modification catalyzed by peptidylarginine deiminase 4 in gene transcriptional regulation

Peptidylarginine deiminase 4 (PADI4), a new histone modification enzyme, which converts both arginine and monomethyl-arginine to citrulline, has gained massive attention in recent years as a potential regulator of gene transcription. Recent studies have shown that arginine residues R2, R8, R17, and R26 in the H3 tail and R3 in the H4 tail can be deiminated by PADI4. This kind of histone post-translational modification has the potential to antagonize histone methylation and coordinate with histone deacetylation to regulate gene transcription. PADI4 also deiminates non-histone proteins, such as p300, NPM1, ING4, RPS2, and DNMT3A. PADI4 has been shown to involve in cell apoptosis and differentiation. Moreover, PADI4 can interact with tumor suppressor p53 and regulate the transcriptional activity of p53. Dysregulation of PADI4 is implicated in a variety of diseases, including rheumatoid arthritis, tumor development, and multiple sclerosis. A wide variety of PADI4 inhibitors have been identified. Further understanding of PADI4 functions may lead to novel diagnostic and therapeutic approaches in these diseases. This review summarizes the recent progress in the study of the regulation mechanism of PADI4 on gene transcription and the major physiological functions of PADI4 in human diseases.

DNA-binding protects p53 from interactions with cofactors involved in transcription-independent functions

Binding-induced conformational changes of a protein at regions distant from the binding site may play crucial roles in protein function and regulation. The p53 tumour suppressor is an example of such an allosterically regulated protein. Little is known, however, about how DNA binding can affect distal sites for transcription factors. Furthermore, the molecular details of how a local perturbation is transmitted through a protein structure are generally elusive and occur on timescales hard to explore by simulations. Thus, we employed state-of-the-art enhanced sampling atomistic simulations to unveil DNA-induced effects on p53 structure and dynamics that modulate the recruitment of cofactors and the impact of phosphorylation at Ser215. We show that DNA interaction promotes a conformational change in a region 3 nm away from the DNA binding site. Specifically, binding to DNA increases the population of an occluded minor state at this distal site by more than 4-fold, whereas phosphorylation traps the protein in its major state. In the minor conformation, the interface of p53 that binds biological partners related to p53 transcription-independent functions is not accessible. Significantly, our study reveals a mechanism of DNA-mediated protection of p53 from interactions with partners involved in the p53 transcription-independent signalling. This also suggests that conformational dynamics is tightly related to p53 signalling.

Molecular mechanism leading to SAHA-induced autophagy in tumor cells: evidence for a p53-dependent pathway

Background

Recent studies indicated that histone deacetylase inhibitors (HDACi), a class of anticancer agents, are in addition to their ability of apoptosis induction also capable of provoking autophagy. Promoted by the treatment of malignant uterine sarcoma cells with the HDACi suberoylanilide hydroxamic acid (SAHA), we previously demonstrated predominant dose-dependent activation of autophagy in ESS-1 cells, but prevalent induction of apoptosis in MES-SA cells.

Methods

In order to extend our previous studies, SAHA-treated ESS-1 and MES-SA cells were monitored for protein expression to reveal differences in known markers of apoptosis explaining the different cytotoxic responses. Further analysis of the identified candidate protein included cell rescue experiments by gene transfer followed by subsequent screening of cells for induction of apoptosis and autophagy by immunoblotting, caspase activity as well as LC3 and MDC/PI staining. LDH release assays were performed to assess the amount of cell-mediated cytotoxicity.

Results

In our search for responsible autophagic regulatory genes upstream of mammalian target of rapamycin (mTOR), we now discovered that, in contrast to MES-SA cells, a TP53-637C>T nonsense mutation located in the transactivating domain of the oncogenic suppressor p53 causes loss of its protein and consequently reduced PUMA induction in ESS-1 cells. Upon re-introduction of wild-type TP53, SAHA-treated ESS-1 cells underwent immediate apoptotic cell death as supported by upregulation of PUMA and caspase-9 as well as by activation of caspases-3 and -7 and PARP-1 cleavage. Concurrent downregulation of autophagy was noticed by upregulated mTor and phospho-mTOR expression as well as monitoring autophagosome formation employing LC3 and MDC staining. Previously, cytoplasmic master regulatory activities of the oncogenic suppressor p53 in inhibiting autophagy and triggering apoptosis were unravelled. Accordingly, p53-deficiency could explain both, the previously documented apoptosis resistance and prevailing SAHA-induced autophagy in ESS-1 cells. Using MES-SA cells with RNAi-silenced p53 expression and several p53-deficient tumor cell lines undergoing SAHA-induced autophagy, we could generally validate our finding suggesting an inhibitory role for p53 in the autophagic pathway in response to SAHA treatment.

Conclusions

Conclusively, these results could identify cytoplasmic p53 protein as a molecular switch that directly mediates the cytotoxic response of SAHA and thus open new therapeutic avenues.

Multiplex Detection of Rare Mutations by Picoliter Droplet Based Digital PCR: Sensitivity and Specificity Considerations

In cancer research, the accuracy of the technology used for biomarkers detection is remarkably important. In this context, digital PCR represents a highly sensitive and reproducible method that could serve as an appropriate tool for tumor mutational status analysis. In particular, droplet-based digital PCR approaches have been developed for detection of tumor-specific mutated alleles within plasmatic circulating DNA. Such an approach calls for the development and validation of a very significant quantity of assays, which can be extremely costly and time consuming. Herein, we evaluated assays for the detection and quantification of various mutations occurring in three genes often misregulated in cancers: the epidermal growth factor receptor (EGFR), the v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) and the Tumoral Protein p53 (TP53) genes. In particular, commercial competitive allele-specific TaqMan® PCR (castPCR™) technology, as well as TaqMan® and ZEN™ assays, have been evaluated for EGFR p.L858R, p.T790M, p.L861Q point mutations and in-frame deletions Del19. Specificity and sensitivity have been determined on cell lines DNA, plasmatic circulating DNA of lung cancer patients or Horizon Diagnostics Reference Standards. To show the multiplexing capabilities of this technology, several multiplex panels for EGFR (several three- and four-plexes) have been developed, offering new "ready-to-use" tests for lung cancer patients.