MEK inhibitors block growth of lung tumours with mutations in ataxia-telangiectasia mutated

Synergistic combination of RAD51-SCR7 improves CRISPR-Cas9 genome editing efficiency by preventing R-loop accumulation

CRISPR-Cas9 has emerged as a powerful tool for genome editing. However, Cas9 genome editing faces challenges, including low efficiency and off-target effects. Here, we report that combined treatment with RAD51, a key factor in homologous recombination, and SCR7, a DNA ligase IV small-molecule inhibitor, enhances CRISPR-Cas9-mediated genome-editing efficiency in human embryonic kidney 293T and human induced pluripotent stem cells, as confirmed by cyro- transmission electron microscopy and functional analyses. First, our findings reveal the crucial role of RAD51 in homologous recombination (HR)-mediated DNA repair process. Elevated levels of exogenous RAD51 promote a post-replication step via single-strand DNA gap repair process, ensuring the completion of DNA replication. Second, using the all-in-one CRISPR-Cas9-RAD51 system, highly expressed RAD51 improved the multiple endogenous gene knockin/knockout efficiency and insertion/deletion (InDel) mutation by activating the HR-based repair pathway in concert with SCR7. Sanger sequencing shows distinct outcomes for RAD51-SCR7 in the ratio of InDel mutations in multiple genome sites. Third, RAD51-SCR7 combination can induce efficient R-loop resolution and DNA repair by enhanced HR process, which leads to DNA replication stalling and thus is advantageous to CRISPR-Cas9-based stable genome editing. Our study suggests promising applications in genome editing by enhancing CRISPR-Cas9 efficiency through RAD51 and SCR7, offering potential advancements in biotechnology and therapeutics.

A clinically compatible in vitro drug-screening platform identifies therapeutic vulnerabilities in primary cultures of brain metastases

PURPOSE

Brain metastases represent the most common intracranial tumors in adults and are associated with a poor prognosis. We used a personalized in vitro drug screening approach to characterize individual therapeutic vulnerabilities in brain metastases.

METHODS

Short-term cultures of cancer cells isolated from brain metastasis patients were molecularly characterized using next-generation sequencing and functionally evaluated using high-throughput in vitro drug screening to characterize pharmacological treatment sensitivities.

RESULTS

Next-generation sequencing identified matched genetic alterations in brain metastasis tissue samples and corresponding short-term cultures, suggesting that short-term cultures of brain metastases are suitable models for recapitulating the genetic profile of brain metastases that may determine their sensitivity to anti-cancer drugs. Employing a high-throughput in vitro drug screening platform, we successfully screened the cultures of five brain metastases for response to 267 anticancer compounds and related drug response to genetic data. Among others, we found that targeted treatment with JAK3, HER2, or FGFR3 inhibitors showed anti-cancer effects in individual brain metastasis cultures.

CONCLUSION

Our preclinical study provides a proof-of-concept for combining molecular profiling with in vitro drug screening for predictive evaluation of therapeutic vulnerabilities in brain metastasis patients. This approach could advance the use of patient-derived cancer cells in clinical practice and might eventually facilitate decision-making for personalized drug treatment.

Targeting the ATM pathway in cancer: Opportunities, challenges and personalized therapeutic strategies

Ataxia telangiectasia mutated (ATM) kinase plays a pivotal role in orchestrating the DNA damage response, maintaining genomic stability, and regulating various cellular processes. This review provides a comprehensive analysis of ATM's structure, activation mechanisms, and various functions in cancer development, progression, and treatment. I discuss ATM's dual nature as both a tumor suppressor and potential promoter of cancer cell survival in certain contexts. The article explores the complex signaling pathways mediated by ATM, its interactions with other DNA repair mechanisms, and its influence on cell cycle checkpoints, apoptosis, and metabolism. I examine the clinical implications of ATM alterations, including their impact on cancer predisposition, prognosis, and treatment response. The review highlights recent advances in ATM-targeted therapies, discussing ongoing clinical trials of ATM inhibitors and their potential in combination with other treatment modalities. I also address the challenges in developing effective biomarkers for ATM activity and patient selection strategies for personalized cancer therapy. Finally, I outline future research directions, emphasizing the need for refined biomarker development, optimized combination therapies, and strategies to overcome potential resistance mechanisms. This comprehensive overview underscores the critical importance of ATM in cancer biology and its emerging potential as a therapeutic target in precision oncology.

Complex synthetic lethality in cancer

The concept of synthetic lethality has been widely applied to identify therapeutic targets in cancer, with varying degrees of success. The standard approach normally involves identifying genetic interactions between two genes, a driver and a target. In reality, however, most cancer synthetic lethal effects are likely complex and also polygenic, being influenced by the environment in addition to involving contributions from multiple genes. By acknowledging and delineating this complexity, we describe in this article how the success rate in cancer drug discovery and development could be improved.

PD0325901, an ERK inhibitor, attenuates RANKL-induced osteoclast formation and mitigates cartilage inflammation by inhibiting the NF-κB and MAPK pathways

Osteoarthritis (OA), a degenerative disease affecting the joint, is characterized by degradation of the joint edge, cartilage injury, and subchondral bone hyperplasia. Treatment of early subchondral bone loss in OA can inhibit subsequent articular degeneration and improve the prognosis of OA. PD0325901, a specific inhibitor of ERK, is widely used in oncology and has potential as a therapeutic agent for osteoarthritis In this study, we investigated the biological function of PD0325901 in bone marrow monocytes/macrophages (BMMs)treated with RANKL and found that it inhibited osteoclast differentiation in vitro in a time- and dose-dependent manner. PD0325901 restrained the expression of osteoclast marker genes, such as c-Fos and NFATc1 induced by RANKL. We tested the biological effects of PD035901 on ATDC5 cells stimulated by IL-1β and found that it had protective effects on ATDC5 cells. In animal studies, we used a destabilization of the medial meniscus (DMM) model and injected 5 mg/kg or 10 mg/kg of PD0325901 compound into each experimental group of mice. We found that PD0325901 significantly reduced osteochondral pathological changes in post-OA subchondral bone destruction.Finally, we found that PD0325901 down-regulated the pyroptosis level in chondrocytes to rescue cartilage degeneration. Therefore, PD0325901 is expected to be a new generation alternative therapy for OA.

ATM inhibition drives metabolic adaptation via induction of macropinocytosis

Macropinocytosis is a nonspecific endocytic process that may enhance cancer cell survival under nutrient-poor conditions. Ataxia-Telangiectasia mutated (ATM) is a tumor suppressor that has been previously shown to play a role in cellular metabolic reprogramming. We report that the suppression of ATM increases macropinocytosis to promote cancer cell survival in nutrient-poor conditions. Combined inhibition of ATM and macropinocytosis suppressed proliferation and induced cell death both in vitro and in vivo. Supplementation of ATM-inhibited cells with amino acids, branched-chain amino acids (BCAAs) in particular, abrogated macropinocytosis. Analysis of ATM-inhibited cells in vitro demonstrated increased BCAA uptake, and metabolomics of ascites and interstitial fluid from tumors indicated decreased BCAAs in the microenvironment of ATM-inhibited tumors. These data reveal a novel basis of ATM-mediated tumor suppression whereby loss of ATM stimulates protumorigenic uptake of nutrients in part via macropinocytosis to promote cancer cell survival and reveal a potential metabolic vulnerability of ATM-inhibited cells.

Targeting K-Ras-mediated DNA damage response in radiation oncology: Current status, challenges and future perspectives

Approximately 60% of cancer patients receive curative or palliative radiation. Despite the significant role of radiotherapy (RT) as a curative approach for many solid tumors, tumor recurrence occurs, partially because of intrinsic radioresistance. Accumulating evidence indicates that the success of RT is hampered by activation of the DNA damage response (DDR). The intensity of DDR signaling is affected by multiple parameters, e.g., loss-of-function mutations in tumor suppressor genes, gain-of-function mutations in protooncogenes as well as radiation-induced alterations in signal-transduction pathways. Therefore, the response to irradiation differs in tumors of different types, which makes the individualization of RT as a rational but challenging goal. One contributor to tumor cell radiation survival is signaling through the Ras pathway. Three RAS genes encode 4 Ras isoforms: K-Ras4A, K-Ras4B, H-Ras, and N-Ras. RAS family members are found to be mutated in approximately 19% of human cancers. Mutations in RAS lead to constitutive activation of the gene product and activation of multiple Ras-dependent signal-transduction cascades. Preclinical studies have shown that the expression of mutant KRAS affects DDR and increases cell survival after irradiation. Approximately 70% of RAS mutations occur in KRAS. Thus, applying targeted therapies directly against K-Ras as well as K-Ras upstream activators and downstream effectors might be a tumor-specific approach to overcome K-Ras-mediated RT resistance. In this review, the role of K-Ras in the activation of DDR signaling will be summarized. Recent progress in targeting DDR in KRAS-mutated tumors in combination with radiochemotherapy will be discussed.

Critical DNA damaging pathways in tumorigenesis

The acquisition of DNA damage is an early driving event in tumorigenesis. Premalignant lesions show activated DNA damage responses and inactivation of DNA damage checkpoints promotes malignant transformation. However, DNA damage is also a targetable vulnerability in cancer cells. This requires a detailed understanding of the cellular and molecular mechanisms governing DNA integrity. Here, we review current work on DNA damage in tumorigenesis. We discuss DNA double strand break repair, how repair pathways contribute to tumorigenesis, and how double strand breaks are linked to the tumor microenvironment. Next, we discuss the role of oncogenes in promoting DNA damage through replication stress. Finally, we discuss our current understanding on DNA damage in micronuclei and discuss therapies targeting these DNA damage pathways.

Cancer Cells Haploinsufficient for ATM Are Sensitized to PARP Inhibitors by MET Inhibition

The MET oncogene encodes a tyrosine kinase (TK) receptor. Its activation protects cells from death but also stimulates DNA damage response by triggering excess replicative stress. Transcriptomic classification of cancer cell lines based on MET expression showed that response to the PARP inhibitor (PARPi) olaparib is poorer in MET overexpressing cell lines. Accordingly, a high MET expressing lung carcinoma cell line was sensitized to PARPi by MET TK inhibition. This was not linked solely to MET overexpression: other MET overexpressing cell lines were biochemically but not functionally responsive to combined inhibition. Moreover, exogenously induced MET overexpression was unable to induce resistance to PARPi. The MET overexpressing cell line, responsive to the combined PARP and MET inhibition, carried a heterozygous mutation of the ATM gene and showed an attenuated response of ATM to PARPi. Among the downstream targets of ATM activation, NuMA was phosphorylated only in response to the combined PARP and MET inhibition. Given the role played by NuMA in mitosis, data show that the latter is affected by MET and PARP inhibition in cells with haploinsufficient ATM. This is important as ATM heterozygous mutation is frequently found in human cancer and in lung carcinomas in particular.

Characterization of KRAS Mutation Subtypes in Non-small Cell Lung Cancer

KRAS is the most commonly mutated oncogene in NSCLC and development of direct KRAS inhibitors has renewed interest in this molecular variant. Different KRAS mutations may represent a unique biologic context with different prognostic and therapeutic impact. We sought to characterize genomic landscapes of advanced, KRAS-mutated non-small cell lung cancer (NSCLC) in a large national cohort to help guide future therapeutic development.Molecular profiles of 17,095 NSCLC specimens were obtained using DNA next-generation sequencing of 592 genes (Caris Life Sciences) and classified on the basis of presence and subtype of KRAS mutations. Co-occurring genomic alterations, tumor mutational burden (TMB), and PD-L1 expression [22C3, tumor proportion score (TPS) score] were analyzed by KRAS mutation type.Across the cohort, 4,706 (27.5%) samples harbored a KRAS mutation. The most common subtype was G12C (40%), followed by G12V (19%) and G12D (15%). The prevalence of KRAS mutations was 37.2% among adenocarcinomas and 4.4% in squamous cell carcinomas. Rates of high TMB (≥10 mutations/Mb) and PD-L1 expression varied across KRAS mutation subtypes. KRAS G12C was the most likely to be PD-L1 positive (65.5% TPS ≥ 1%) and PD-L1 high (41.3% TPS ≥ 50%). STK11 was mutated in 8.6% of KRAS wild-type NSCLC but more frequent in KRAS-mutant NSCLC, with the highest rate in G13 (36.2%). TP53 mutations were more frequent in KRAS wild-type NSCLC (73.6%).KRAS mutation subtypes have different co-occurring mutations and a distinct genomic landscape. The clinical relevance of these differences in the context of specific therapeutic interventions warrants investigation.

The AML microenvironment catalyzes a stepwise evolution to gilteritinib resistance

Our study details the stepwise evolution of gilteritinib resistance in FLT3-mutated acute myeloid leukemia (AML). Early resistance is mediated by the bone marrow microenvironment, which protects residual leukemia cells. Over time, leukemia cells evolve intrinsic mechanisms of resistance, or late resistance. We mechanistically define both early and late resistance by integrating whole-exome sequencing, CRISPR-Cas9, metabolomics, proteomics, and pharmacologic approaches. Early resistant cells undergo metabolic reprogramming, grow more slowly, and are dependent upon Aurora kinase B (AURKB). Late resistant cells are characterized by expansion of pre-existing NRAS mutant subclones and continued metabolic reprogramming. Our model closely mirrors the timing and mutations of AML patients treated with gilteritinib. Pharmacological inhibition of AURKB resensitizes both early resistant cell cultures and primary leukemia cells from gilteritinib-treated AML patients. These findings support a combinatorial strategy to target early resistant AML cells with AURKB inhibitors and gilteritinib before the expansion of pre-existing resistance mutations occurs.

Synergistic targeting and resistance to PARP inhibition in DNA damage repair-deficient pancreatic cancer

OBJECTIVE

ATM serine/threonine kinase (ATM) is the most frequently mutated DNA damage response gene, involved in homologous recombination (HR), in pancreatic ductal adenocarcinoma (PDAC).

DESIGN

Combinational synergy screening was performed to endeavour a genotype-tailored targeted therapy.

RESULTS

Synergy was found on inhibition of PARP, ATR and DNA-PKcs (PAD) leading to synthetic lethality in ATM-deficient murine and human PDAC. Mechanistically, PAD-induced PARP trapping, replication fork stalling and mitosis defects leading to P53-mediated apoptosis. Most importantly, chemical inhibition of ATM sensitises human PDAC cells toward PAD with long-term tumour control in vivo. Finally, we anticipated and elucidated PARP inhibitor resistance within the ATM-null background via whole exome sequencing. Arising cells were aneuploid, underwent epithelial-mesenchymal-transition and acquired multidrug resistance (MDR) due to upregulation of drug transporters and a bypass within the DNA repair machinery. These functional observations were mirrored in copy number variations affecting a region on chromosome 5 comprising several of the upregulated MDR genes. Using these findings, we ultimately propose alternative strategies to overcome the resistance.

CONCLUSION

Analysis of the molecular susceptibilities triggered by ATM deficiency in PDAC allow elaboration of an efficient mutation-specific combinational therapeutic approach that can be also implemented in a genotype-independent manner by ATM inhibition.

Effect of Reducing Ataxia-Telangiectasia Mutated (ATM) in Experimental Autosomal Dominant Polycystic Kidney Disease

The DNA damage response (DDR) pathway is upregulated in autosomal dominant polycystic kidney disease (ADPKD) but its functional role is not known. The ataxia-telangiectasia mutated (ATM) and AT and Rad3-related (ATR) protein kinases are key proximal transducers of the DDR. This study hypothesized that reducing either ATM or ATR attenuates kidney cyst formation and growth in experimental ADPKD. In vitro, pharmacological ATM inhibition by AZD0156 reduced three-dimensional cyst growth in MDCK and human ADPKD cells by up to 4.4- and 4.1-fold, respectively. In contrast, the ATR inhibitor, VE-821, reduced in vitro MDCK cyst growth but caused dysplastic changes. In vivo, treatment with AZD0156 by oral gavage for 10 days reduced renal cell proliferation and increased p53 expression in Pkd1^RC/RC mice (a murine genetic ortholog of ADPKD). However, the progression of cystic kidney disease in Pkd1^RC/RC mice was not altered by genetic ablation of ATM from birth, in either heterozygous (Pkd1^RC/RC/Atm^+/−) or homozygous (Pkd1^RC/RC/Atm^−/−) mutant mice at 3 months. In conclusion, despite short-term effects on reducing renal cell proliferation, chronic progression was not altered by reducing ATM in vivo, suggesting that this DDR kinase is dispensable for kidney cyst formation in ADPKD.

Mitogen-activated protein kinase inhibition-induced modulation of epidermal growth factor receptor signaling in human head and neck squamous cell carcinoma

BACKGROUND

Epidermal growth factor receptor (EGFR) overexpression is one of the most notable characteristics in head and neck squamous cell carcinoma (HNSCC). The MAPK kinase (MEK) inhibitor trametinib has shown efficacy to treat HNSCC; however, the molecular mechanism remains unclear.

METHODS

HNSCC lines, mouse models, Western blot, and flow cytometry were employed to analyze the anticancer effects of trametinib.

RESULTS

The JHU-011, JHU-022, and JHU-029 HNSCC cells with different genetic alterations were highly susceptible to trametinib. Trametinib effectively reduced EGFR expression, which was accompanied by the reduction of pro-survival protein MYC, and the increased expression of a MYC-targeted cyclin-dependent kinase inhibitor p27kip1 and pro-apoptotic protein BIM. Trametinib resulted in G1 arrest of the cells, markedly reduced cell numbers in S phase, and significantly increased apoptosis. In mouse models, trametinib strongly inhibited tumors growth.

CONCLUSIONS

The MAPK-ERK signaling inhibition by trametinib may target EGFR and the downstream proteins against HNSCC.

Targeting IGF Perturbs Global Replication through Ribonucleotide Reductase Dysfunction

Inhibition of IGF receptor (IGF1R) delays repair of radiation-induced DNA double-strand breaks (DSB), prompting us to investigate whether IGF1R influences endogenous DNA damage. Here we demonstrate that IGF1R inhibition generates endogenous DNA lesions protected by 53BP1 bodies, indicating under-replicated DNA. In cancer cells, inhibition or depletion of IGF1R delayed replication fork progression accompanied by activation of ATR-CHK1 signaling and the intra-S-phase checkpoint. This phenotype reflected unanticipated regulation of global replication by IGF1 mediated via AKT, MEK/ERK, and JUN to influence expression of ribonucleotide reductase (RNR) subunit RRM2. Consequently, inhibition or depletion of IGF1R downregulated RRM2, compromising RNR function and perturbing dNTP supply. The resulting delay in fork progression and hallmarks of replication stress were rescued by RRM2 overexpression, confirming RRM2 as the critical factor through which IGF1 regulates replication. Suspecting existence of a backup pathway protecting from toxic sequelae of replication stress, targeted compound screens in breast cancer cells identified synergy between IGF inhibition and ATM loss. Reciprocal screens of ATM-proficient/deficient fibroblasts identified an IGF1R inhibitor as the top hit. IGF inhibition selectively compromised growth of ATM-null cells and spheroids and caused regression of ATM-null xenografts. This synthetic-lethal effect reflected conversion of single-stranded lesions in IGF-inhibited cells into toxic DSBs upon ATM inhibition. Overall, these data implicate IGF1R in alleviating replication stress, and the reciprocal IGF:ATM codependence we identify provides an approach to exploit this effect in ATM-deficient cancers. SIGNIFICANCE: This study identifies regulation of ribonucleotide reductase function and dNTP supply by IGFs and demonstrates that IGF axis blockade induces replication stress and reciprocal codependence on ATM. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/8/2128/F1.large.jpg.

BRAF paradox breakers PLX8394, PLX7904 are more effective against BRAFV600Ε CRC cells compared with the BRAF inhibitor PLX4720 and shown by detailed pathway analysis

PLX7904 and PLX8394 are novel BRAFV600E inhibitors-BRAFi that are designed to evade the paradoxical MAPK activation, a trait for the name "paradox breakers"-PB. Current FDA approved inhibitors (Vemurafenib, Dabrafenib, Encorafenib) although improved progression-free survival of mtBRAF melanoma patients suffer from this treatment related side effect. mtBRAF Colorectal Cancer (CRC) is resistant to the approved BRAF inhibitors, although combinatorial treatment co-targeting BRAF and EGFR/MEK is offering a promising prospect. In an effort to explore the potential of the novel BRAF inhibitors-PB to impede CRC cell proliferation, they were tested on RKO, HT29 and Colo-205 cells, bearing the BRAFV600E mutation. This study shows that the BRAF paradox breakers PLX7904 and PLX8394 cause a more prolonged MAPK pathway inhibition and achieve a stronger blockage of proliferation and reduced viability than PLX4720, the sister compound of Vemurafenib. In some treatment conditions, cells can undergo apoptosis. Genomic analysis on the more resistant RKO cells treated with PLX7904, PLX8394 and PLX4720 showed similar gene expression pattern, but the alterations imposed by the PB were more intense. Bioinformatic analysis resulted in a short list of genes representing potential master regulators of the cellular response to BRAF inhibitors' treatments. From our results, it is clear that the BRAF paradox breakers present a notable differential regulation of major pathways, like MAPK signalling, apoptosis, cell cycle, or developmental signalling pathways. Combinatorial treatments of BRAFi with Mcl-1 and Notch modulators show a better effect than mono-treatments. Additional pathways could be further exploited in novel efficient combinatorial treatment protocols with BRAFi.

Synthetic Lethality through the Lens of Medicinal Chemistry

Personalized medicine and therapies represent the goal of modern medicine, as drug discovery strives to move away from one-cure-for-all and makes use of the various targets and biomarkers within differing disease areas. This approach, especially in oncology, is often undermined when the cells make use of alternative survival pathways. As such, acquired resistance is unfortunately common. In order to combat this phenomenon, synthetic lethality is being investigated, making use of existing genetic fragilities within the cancer cell. This Perspective highlights exciting targets within synthetic lethality, (PARP, ATR, ATM, DNA-PKcs, WEE1, CDK12, RAD51, RAD52, and PD-1) and discusses the medicinal chemistry programs being used to interrogate them, the challenges these programs face, and what the future holds for this promising field.

DrugSniper, a Tool to Exploit Loss-Of-Function Screens, Identifies CREBBP as a Predictive Biomarker of VOLASERTIB in Small Cell Lung Carcinoma (SCLC)

The development of predictive biomarkers of response to targeted therapies is an unmet clinical need for many antitumoral agents. Recent genome-wide loss-of-function screens, such as RNA interference (RNAi) and CRISPR-Cas9 libraries, are an unprecedented resource to identify novel drug targets, reposition drugs and associate predictive biomarkers in the context of precision oncology. In this work, we have developed and validated a large-scale bioinformatics tool named DrugSniper, which exploits loss-of-function experiments to model the sensitivity of 6237 inhibitors and predict their corresponding biomarkers of sensitivity in 30 tumor types. Applying DrugSniper to small cell lung cancer (SCLC), we identified genes extensively explored in SCLC, such as Aurora kinases or epigenetic agents. Interestingly, the analysis suggested a remarkable vulnerability to polo-like kinase 1 (PLK1) inhibition in CREBBP-mutant SCLC cells. We validated this association in vitro using four mutated and four wild-type SCLC cell lines and two PLK1 inhibitors (Volasertib and BI2536), confirming that the effect of PLK1 inhibitors depended on the mutational status of CREBBP. Besides, DrugSniper was validated in-silico with several known clinically-used treatments, including the sensitivity of Tyrosine Kinase Inhibitors (TKIs) and Vemurafenib to FLT3 and BRAF mutant cells, respectively. These findings show the potential of genome-wide loss-of-function screens to identify new personalized therapeutic hypotheses in SCLC and potentially in other tumors, which is a valuable starting point for further drug development and drug repositioning projects.

AR phosphorylation and CHK2 kinase activity regulates IR-stabilized AR-CHK2 interaction and prostate cancer survival

We have previously demonstrated that checkpoint kinase 2 (CHK2) is a critical negative regulator of androgen receptor (AR) transcriptional activity, prostate cancer (PCa) cell growth, and androgen sensitivity. We have now uncovered that the AR directly interacts with CHK2 and ionizing radiation (IR) increases this interaction. This IR-induced increase in AR-CHK2 interactions requires AR phosphorylation and CHK2 kinase activity. PCa associated CHK2 mutants with impaired kinase activity reduced IR-induced AR-CHK2 interactions. The destabilization of AR - CHK2 interactions induced by CHK2 variants impairs CHK2 negative regulation of cell growth. CHK2 depletion increases transcription of DNAPK and RAD54, increases clonogenic survival, and increases resolution of DNA double strand breaks. The data support a model where CHK2 sequesters the AR through direct binding decreasing AR transcription and suppressing PCa cell growth. CHK2 mutation or loss of expression thereby leads to increased AR transcriptional activity and survival in response to DNA damage.

Lamin B1 Overexpresses in Lung Adenocarcinoma and Promotes Proliferation in Lung Cancer Cells via AKT Pathway

PURPOSE

This study aims to investigate the biological effect and molecular mechanism of Lamin B1(LMNB1) in lung cancer cells and its significance for the prognosis of lung adenocarcinoma(LUAD) patients.

METHODS

In this study, Bioinformatics was performed to analyze the expression at mRNA level and prognosis effect of LMNB1 in LUAD from TCGA dataset. The immunohistochemistry(IHC) assay was conducted to analyzed the expression of LMNB1 at the protein level in LUAD tissues. The correlation between the expression of LMNB1 and the clinical factors in patients with LUAD was analyzed. Next, LMNB1 transfected into LUAD cell lines (A549 and PC-9) which was proved by Western blot. CCK8 assay, cloning formation assay, and xenograft assay were conducted to explore the effect and mechanism of LMNB1 on the proliferation of LUAD cell lines in vitro and in vivo.

RESULTS

The results of the present study demonstrated that LMNB1 was highly expressed in LUAD tissues and related to tumor stage. High LMNB1 expression was related with more advanced clinicopathological factors such as low degree of differentiation (P=0.02), large tumor size (P<0.01), lymph node metastasis (P<0.01) and higher tumor stage (P<0.01). After knocking down LMNB1, the cell growth rate (P<0.01) and the number of colonies (P<0.01) were significantly reduced, and the level of the proliferating marker Ki67 (P<0.01) was significantly decreased. At the same time, in vivo experiments showed that the tumor volume and tumor of the mice were significantly reduced (P<0.01). Moreover, we found that knockdown LMNB1 can inhibit the proliferation of lung cancer cells by inhibiting AKT phosphorylation by Western blot.

CONCLUSION

In summary, LMNB1 play an of vital roles in the growth of LUAD cells, highlighting its potential as a therapeutic target for the treatment of LUAD patients.

The ATM rs189037 G>A polymorphism is associated with the risk and prognosis of gastric cancer in Chinese individuals: A case-control study

The ataxia telangiectasia mutated (ATM) gene is involved in repairing DNA lesions and maintaining genome stability, which is related to cancer invasion and metastasis. This gene influences the risk of cancers. Many studies have demonstrated that the ATM rs189037 G>A polymorphism is linked with the risks of different types of cancer. However, no study has probed the relationship between the ATM rs189037 G>A polymorphism and gastric cancer (GC) risk. Therefore, the aims of this study were to investigate the association of the ATM rs189037 G>A polymorphism with the risk and prognosis of GC in a case-control investigation of 345 GC patients and 467 controls in China. The rs189037 G>A polymorphism was genotyped using polymerase chain reaction-restriction fragment length polymorphism. This polymorphism was related to a significantly higher risk of GC [AA vs. GG: OR (95% CI): 1.80 (1.20-2.70), P = 0.04; GG vs. AA + GA: 1.46 (1.08-1.98); A vs. G: 1.34 (1.10-1.64), P = 0.004]. Subgroup analyses showed significant associations with female gender, smoking, alcohol consumption, age ≥60 years, and positive Helicobacter pylori status. This polymorphism was also correlated with TNM stage III + IV and tumor size >4 cm. GC patients carrying the AA genotype of the rs189037 polymorphism also had lower overall survival. In conclusion, the ATM rs189037 G>A polymorphism was related to increased susceptibility to and poorer prognosis in GC in this Chinese population.

Co-occurring genomic alterations in non-small-cell lung cancer biology and therapy

The impressive clinical activity of small-molecule receptor tyrosine kinase inhibitors for oncogene-addicted subgroups of non-small-cell lung cancer (for example, those driven by activating mutations in the gene encoding epidermal growth factor receptor (EGFR) or rearrangements in the genes encoding the receptor tyrosine kinases anaplastic lymphoma kinase (ALK), ROS proto-oncogene 1 (ROS1) and rearranged during transfection (RET)) has established an oncogene-centric molecular classification paradigm in this disease. However, recent studies have revealed considerable phenotypic diversity downstream of tumour-initiating oncogenes. Co-occurring genomic alterations, particularly in tumour suppressor genes such as TP53 and LKB1 (also known as STK11), have emerged as core determinants of the molecular and clinical heterogeneity of oncogene-driven lung cancer subgroups through their effects on both tumour cell-intrinsic and non-cell-autonomous cancer hallmarks. In this Review, we discuss the impact of co-mutations on the pathogenesis, biology, microenvironmental interactions and therapeutic vulnerabilities of non-small-cell lung cancer and assess the challenges and opportunities that co-mutations present for personalized anticancer therapy, as well as the expanding field of precision immunotherapy.

Synthetically Lethal Interactions of ATM, ATR, and DNA-PKcs

Synthetic lethality occurs when simultaneous perturbations of two genes or molecular processes result in a loss of cell viability. The number of known synthetically lethal interactions is growing steadily. We review here synthetically lethal interactions of ataxia-telangiectasia mutated (ATM), ATM- and Rad3-related (ATR), and DNA-dependent protein kinase catalytic subunit (DNA-PKcs). These kinases are appropriate for synthetic lethal therapies because their genes are frequently mutated in cancer, and specific inhibitors are currently in clinical trials. Understanding synthetically lethal interactions of a particular gene or gene family can facilitate predicting new synthetically lethal interactions, therapy toxicity, and mechanisms of resistance, as well as defining the spectrum of tumors amenable to these therapeutic approaches.

miR-7 Suppresses Tumor Progression by Directly Targeting MAP3K9 in Pancreatic Cancer

Extensive research has suggested that miR-7 plays a critical role in cancer progression. However, the biological function of miR-7 in pancreatic cancer (PC) progression is poorly understood. Therefore, in the present study, we investigated the function of miR-7 and its molecular mechanism in PC progression. We used multiple methods, such as MTT, FACS, Transwell assay, RT-PCR, western blotting, and transfection to investigate the role of miR-7 in PC cells. We found that miR-7 suppressed cell growth, migration, and invasion but induced apoptosis in PC cells. Moreover, overexpression of miR-7 repressed tumor growth in mice, suggesting that miR-7 could exert its tumor-suppressive function in PC. Mechanistically, we validated that MAP3K9 is a direct target of miR-7, which significantly enhanced PC cell proliferation and inhibited cell apoptosis partly through activation of the MEK/ERK pathway and NF-κB pathway. Moreover, rescue experiments also showed that miR-7 suppressed PC cell proliferation and induced PC cell apoptosis by directly targeting MAP3K9, leading to inhibition of the MEK/ERK and NF-κB pathways. Taken together, these results suggest that miR-7/MAP3K9 is critically involved in PC progression and that miR-7 may be a potential target for PC treatment.

[Research Progress of Targeted Therapy for BRAF Mutation in Advanced Non-small Cell Lung Cancer]

靶向治疗是驱动基因阳性晚期非小细胞肺癌（non-small cell lung cancer, NSCLC）的重要治疗手段之一。鼠类肉瘤病毒癌基因同源物B1（v-raf murine sar-coma viral oncogene homolog B1, BRAF）基因是继表皮生长因子受体（epidermal growth factor receptor, EGFR）基因突变、间变性淋巴瘤激酶（anaplastic lymphoma kinase, ALK）基因融合和ROS1基因重排之后，NSCLC又一个重要的驱动基因。BRAF V600E突变占BRAF基因突变的一半以上，是晚期NSCLC的潜在治疗靶点，本文主要对BRAF基因突变类型及相关靶向研究进展进行综述。。

Targeted Tumor Therapy Remixed-An Update on the Use of Small-Molecule Drugs in Combination Therapies

Over the last decade, the treatment of tumor patients has been revolutionized by the highly successful introduction of novel targeted therapies, in particular small-molecule kinase inhibitors and monoclonal antibodies, as well as by immunotherapies. Depending on the mutational status, BRAF and MEK inhibitor combinations or immune checkpoint inhibitors are current first-line treatments for metastatic melanoma. However, despite great improvements of survival rates limitations due to tumor heterogeneity, primary and acquired therapy resistance, immune evasion, and economical considerations will need to be overcome. Accordingly, ongoing clinical trials explore the individualized use of small-molecule drugs in new targeted therapy combinations based on patient parameters and tumor biopsies. With focus on melanoma therapy this review aims at providing a comprehensive overview of such novel alternative and combinational therapy strategies currently emerging from basic research. The molecular principles and drug classes that may hold promise for improved tumor therapy combination regimens including kinase inhibition, induction of apoptosis, DNA-damage response inhibition, epigenetic reprogramming, telomerase inhibition, redox modulation, metabolic reprogramming, proteasome inhibition, cancer stem cell transdifferentiation, immune cell signaling modulation, and others, are explained in brief. In addition, relevant targeted therapy combinations in current clinical trials and individualized treatment strategies are highlighted.

Fanconi Anemia Signaling and Cancer

The extremely high cancer incidence associated with patients suffering from a rare human genetic disease, Fanconi anemia (FA), demonstrates the importance of FA genes. Over the course of human tumor development, FA genes perform critical tumor-suppression roles. In doing so, FA provides researchers with a unique genetic model system to study cancer etiology. Here, we review how aberrant function of the 22 FA genes and their signaling network contributes to malignancy. From this perspective, we will also discuss how the knowledge discovered from FA research serves basic and translational cancer research.

DNA damage response inhibitors: Mechanisms and potential applications in cancer therapy

Over the last decade the unravelling of the molecular mechanisms of the DNA damage response pathways and of the genomic landscape of human tumors have paved the road to new therapeutic approaches in oncology. It is now clear that tumors harbour defects in different DNA damage response steps, mainly signalling and repair, rendering them more dependent on the remaining pathways. We here focus on the proteins ATM, ATR, CHK1 and WEE1, reviewing their roles in the DNA damage response and as targets in cancer therapy. In the last decade specific inhibitors of these proteins have been designed, and their potential antineoplastic activity has been explored both in monotherapy strategies against tumors with specific defects (synthetic lethality approach) and in combination with radiotherapy or chemotherapeutic or molecular targeted agents. The preclinical and clinical evidence of antitumor activity of these inhibitors emanating from these research efforts will be critically reviewed. Lastly, the potential therapeutic feasibility of combining together such inhibitors with the aim to target particular subsets of tumors will be also discussed.

Susceptibility of ATM-deficient pancreatic cancer cells to radiation

Ataxia telangiectasia mutated (ATM) is inactivated in a significant minority of pancreatic ductal adenocarcinomas and may be predictor of treatment response. We determined if ATM deficiency renders pancreatic cancer cells more sensitive to fractionated radiation or commonly used chemotherapeutics. ATM expression was knocked down in three pancreatic cancer cell lines using ATM-targeting shRNA. Isogenic cell lines were tested for sensitivity to several chemotherapeutic agents and radiation. DNA repair kinetics were analyzed in irradiated cells using the comet assay. We find that while rendering pancreatic cancer cells ATM-deficient did not significantly change their sensitivity to several chemotherapeutics, it did render them exquisitely sensitized to radiation. Pancreatic cancer ATM status may help predict response to radiotherapy.