KRAS mutation: from undruggable to druggable in cancer

Cancer is the leading cause of death worldwide, and its treatment and outcomes have been dramatically revolutionised by targeted therapies. As the most frequently mutated oncogene, Kirsten rat sarcoma viral oncogene homologue (KRAS) has attracted substantial attention. The understanding of KRAS is constantly being updated by numerous studies on KRAS in the initiation and progression of cancer diseases. However, KRAS has been deemed a challenging therapeutic target, even “undruggable”, after drug-targeting efforts over the past four decades. Recently, there have been surprising advances in directly targeted drugs for KRAS, especially in KRAS (G12C) inhibitors, such as AMG510 (sotorasib) and MRTX849 (adagrasib), which have obtained encouraging results in clinical trials. Excitingly, AMG510 was the first drug-targeting KRAS (G12C) to be approved for clinical use this year. This review summarises the most recent understanding of fundamental aspects of KRAS, the relationship between the KRAS mutations and tumour immune evasion, and new progress in targeting KRAS, particularly KRAS (G12C). Moreover, the possible mechanisms of resistance to KRAS (G12C) inhibitors and possible combination therapies are summarised, with a view to providing the best regimen for individualised treatment with KRAS (G12C) inhibitors and achieving truly precise treatment.

Physalin B attenuates liver fibrosis via suppressing LAP2α-HDAC1 mediated deacetylation of GLI1 and hepatic stellate cell activation

Background and Purpose: Liver fibrosis is one of the leading causes of morbidity and mortality worldwide of which no acceptable therapy exists. Accumulating evidence supports that glioma-associated oncogene homologue 1(GLI1) is a potentially important therapeutic target for liver fibrosis. This study investigates the antifibrotic activities and potential mechanisms of Physalin B (PB), a natural Solanaceae compound. Experimental Approach: Mice subjected to CCl4 challenge and bile duct ligation were used to study the antifibrotic effects of PB in vivo. Mouse primary hepatic stellate cells (pHSCs) and human HSC line LX‐2 also served as an in vitro liver fibrosis model. Liver fibrogenic genes, GLI1 downstream genes were examined using western blot and real-time PCR analyses. GLI1 acetylation and LAP2α-HDAC1 interaction were analyzed by coimmunoprecipitation. Key Results: In animal models, PB administration attenuated hepatic histopathological injury, collagen accumulation, and reduced the expression of fibrogenic genes. PB dose‐dependently suppressed fibrotic marker expression in LX‐2 cells and mouse pHSCs. Mechanistic studies showed PB inhibited GLI activity in a non-canonical Hedgehog signaling. PB blocked lamina-associated polypeptide 2 α (LAP2α)/ histone deacetylase 1 (HDAC1) complex formation thereby inhibited HDAC1mediated GLI1 deacetylation. PB downregulated the acetylation and expression of GLI1, and subsequently inhibiting HSC activation. Conclusions and Implications: PB exerted potent antifibrotic effects in vitro and in vivo by disrupting the LAP2α/HDAC1 complex, increasing GLI1 acetylation and inactivating GLI1. This indicates that PB may be a potential therapeutic candidate for the treatment of liver fibrosis.

Mast Cells, microRNAs and Others: The Role of Translational Research on Colorectal Cancer in the Forthcoming Era of Precision Medicine

Colorectal cancer (CRC) is a heterogeneous disease, molecularly and anatomically, that develops in a multi-step process requiring the accumulation of several genetic or epigenetic mutations that lead to the gradual transformation of normal mucosa into cancer. In fact, tumorigenesis is extremely complex, with many immunologic and non-immunologic factors present in the tumor microenvironment that can influence tumorigenesis. In the last few years, a role for mast cells (MCs), microRNAs (miRNAs), Kirsten rat sarcoma (KRAS) and v-raf murine sarcoma viral oncogene homologue B (BRAF) in cancer development and progression has been suggested, and numerous efforts have been made to thoroughly assess their correlation with CRC to improve patient survival and quality of life. The identification of easily measurable, non-invasive and cost-effective biomarkers, the so-called “ideal biomarkers”, for CRC screening and treatment remains a high priority. The aim of this review is to discuss the emerging role of mast cells (MCs), microRNAs (miRNAs), KRAS and BRAF as diagnostic and prognostic biomarkers for CRC, evaluating their influence as potential therapy targets in the forthcoming era of precision medicine.

Orchestration of Intracellular Circuits by G Protein-Coupled Receptor 39 for Hepatitis B Virus Proliferation

Hepatitis B virus (HBV), a highly persistent pathogen causing hepatocellular carcinoma (HCC), takes full advantage of host machinery, presenting therapeutic targets. Here we aimed to identify novel druggable host cellular factors using the reporter HBV we have recently generated. In an RNAi screen of G protein-coupled receptors (GPCRs), GPCR39 (GPR39) appeared as the top hit to facilitate HBV proliferation. Lentiviral overexpression of active GPR39 proteins and an agonist enhanced HBV replication and transcriptional activities of viral promoters, inducing the expression of CCAAT/enhancer binding protein (CEBP)-β (CEBPB). Meanwhile, GPR39 was uncovered to activate the heat shock response, upregulating the expression of proviral heat shock proteins (HSPs). In addition, glioma-associated oncogene homologue signaling, a recently reported target of GPR39, was suggested to inhibit HBV replication and eventually suppress expression of CEBPB and HSPs. Thus, GPR39 provirally governed intracellular circuits simultaneously affecting the carcinopathogenetic gene functions. GPR39 and the regulated signaling networks would serve as antiviral targets, and strategies with selective inhibitors of GPR39 functions can develop host-targeted antiviral therapies preventing HCC.

Small Molecule KRAS Inhibitors: The Future for Targeted Pancreatic Cancer Therapy?

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest solid tumors in the world. Currently, there are no approved targeted therapies for PDAC. Mutations in Kirsten rat sarcoma viral oncogene homologue (KRAS) are known to be a major driver of PDAC progression, but it was considered an undruggable target until recently. Moreover, PDAC also suffers from drug delivery issues due to the highly fibrotic tumor microenvironment. In this perspective, we provide an overview of recent developments in targeting mutant KRAS and strategies to overcome drug delivery issues (e.g., nanoparticle delivery). Overall, we propose that the antitumor effects from novel KRAS inhibitors along with strategies to overcome drug delivery issues could be a new therapeutic way forward in PDAC.

Vaginal dryness in primary Sjögren’s syndrome: a histopathological case–control study

Objective The aim was to study clinical, histopathological and immunological changes in the vagina and cervix of women with primary SS, which might explain vaginal dryness. Methods We included 10 pre-menopausal female primary SS patients with vaginal dryness and 10 pre-menopausal controls undergoing a laparoscopic procedure. The vaginal health index was recorded. Multiplex immunoassays and flow cytometry were performed on endocervical swab and cervicovaginal lavage samples to evaluate cellular and soluble immune markers. Mid-vaginal and endocervical biopsies were taken and stained for various leucocyte markers, caldesmon (smooth muscle cells), avian V-ets erythroblastosis virus E26 oncogene homologue (ERG; endothelial cells) and anti-podoplanin (lymphatic endothelium). The number of positive pixels per square micrometre was calculated. Results One patient was excluded because of Clamydia trachomatis, and two controls were excluded because of endometriosis observed during their laparoscopy. Vaginal health was impaired in primary SS. CD45+ cells were increased in vaginal biopsies of women with primary SS compared with controls. Infiltrates were predominantly located in the peri-epithelial region, and mostly consisted of CD3+ lymphocytes. In the endocervix, CD45+ infiltrates were present in patients and in controls, but a higher number of B lymphocytes was seen in primary SS. Vascular smooth muscle cells were decreased in the vagina of primary SS patients. No differences were found in leucocyte subsets in the vaginal and endocervical lumen. CXCL10 was increased in endocervical swab samples of primary SS patients. Conclusion Women with primary SS show impaired vaginal health and increased lymphocytic infiltration in the vagina compared with controls. Vaginal dryness in primary SS might be caused by vascular dysfunction, possibly induced by IFN-mediated pathways.

Kirsten Rat Sarcoma Viral Oncogene Homologue (KRAS) Mutations in the Occurrence and Treatment of Pancreatic Cancer

: Pancreatic cancer is a highly malignant tumor with a 5-year survival rate of less than 6%, and incidence increasing year by year globally. Pancreatic cancer has a poor prognosis and a high recurrence rate, almost the same as the death rate. However, the available effective prevention and treatment measures for pancreatic cancer are still limited. The genome variation is one of the main reasons for the development of pancreatic cancer. In recent years, with the development of gene sequencing technology, in-depth research on pancreatic cancer gene mutation presents that a growing number of genetic mutations are confirmed to be in a close relationship with invasion and metastasis of pancreatic cancer. Among them, KRAS mutation is a special one. Therefore, it is particularly important to understand the mechanism of the KRAS mutation in the occurrence and development of pancreatic cancer, and to explore the method of its transformation into clinical tumor molecular targeted treatment sites, to further improve the therapeutic effect on pancreatic cancer. Therefore, to better design chemical drugs, this review based on the biological functions of KRAS, summarized the types of KRAS mutations and their relationship with pancreatic cancer and included the downstream signaling pathway Raf-MEK-ERK, PI3K-AKT, RalGDS-Ral of KRAS and the current medicinal treatment methods for KRAS mutations. Moreover, drug screening and clinical treatment for KRAS mutated cell and animal models of pancreatic cancer are also reviewed along with the prospect of targeted medicinal chemistry therapy for precision treatment of pancreatic cancer in the future.

The Prevalence of BRAF Mutations in Patients with Glioma: A Systematic Review

Background The V600mutation in the v-raf murine sarcoma oncogene homologue B1 (BRAF) enzyme, is a potential clinically actionable target in gliomas. BRAF inhibitors are in wide clinical use for other tumour types, particularly melanoma. The prevalence of this mutation across all gliomas is not fully elucidated and is needed to inform potential screening and treatment. Methods A systematic review using articles on the MEDLINE and EMBASE databases (February 1, 2019) was carried out. A meta-analysis was conducted to calculate the prevalence of BRAF mutations in patients with gliomas across all populations and age groups in a clinical setting. Preliminary Results The review identified 75 studies including 6316 patients; the ages of participants ranged from 30 days to 90 years with a mean age of 32.75 years. Across all studies, the average prevalence of BRAF mutations was 16% (95% confidence interval (CI) from 12% to 20%) but estimates were highly variable across studies, ranging from 0% to 78%. The average prevalence of BRAF mutations in paediatric group was 15% (95% CI 10% to 20%) while the average prevalence in the adult group was 9% (95% CI 4% to 16%). Low grade gliomas had an average prevalence of 19% (95% CI 14% to 25%) compared with 7% (95% CI 4% to 11%) in high-grade gliomas. Conclusions BRAF mutations were found to be more prevalent in pediatric patients and in low grade gliomas. Screening these patients for BRAF mutations and treating them with BRAF inhibitors represents a promising area of future medical practice.

Transcriptome profiling reveals the complexity of pirfenidone effects in idiopathic pulmonary fibrosis

Despite the beneficial effects of pirfenidone in treating idiopathic pulmonary fibrosis (IPF), it remains unclear if lung fibroblasts (FB) are the main therapeutic target.To resolve this question, we employed a comparative transcriptomic approach and analysed lung homogenates (LH) and FB derived from IPF patients treated with or without pirfenidone.In FB, pirfenidone therapy predominantly affected growth and cell division pathways, indicating a major cellular metabolic shift. In LH samples, pirfenidone treatment was mostly associated with inflammation-related processes. In FB and LH, regulated genes were over-represented in the Gene Ontology node “extracellular matrix”. We identified lower expression of cell migration-inducing and hyaluronan-binding protein (CEMIP) in both LH and FB from pirfenidone-treated IPF patients. Plasma levels of CEMIP were elevated in IPF patients compared to healthy controls and decreased after 7 months of pirfenidone treatment. CEMIP expression in FB was downregulated in a glioma-associated oncogene homologue-dependent manner and CEMIP silencing in IPF FB reduced collagen production and attenuated cell proliferation and migration.Cumulatively, our approach indicates that pirfenidone exerts beneficial effects via its action on multiple pathways in both FB and other pulmonary cells, through its ability to control extracellular matrix architecture and inflammatory reactions.

Detection of EGFR, KRAS and BRAF mutations in metastatic cells from cerebrospinal fluid

Background:In lung adenocarcinoma, molecular profiling of actionable genes has become essential to set up targeted therapies. However, the feasibility and the relevance of molecular profiling from the cerebrospinal fluid (CSF) in the context of meningeal metastasis have been poorly assessed.Methods:We selected patients with stage IV lung adenocarcinoma harbouring metastatic cells in the CSF after cytological analysis. Seven samples from six patients were eligible for molecular testing of epidermal growth factor receptor (EGFR), V-Ki-ras2 Kirsten rat sarcoma viral oncogene homologue (KRAS), v-Raf murine sarcoma viral oncogene homologue B1 (BRAF) and human epidermal growth factor receptor 2 (HER2) mutations using quantitative polymerase chain reaction (PCR) high-resolution melting curve analysis and Sanger sequencing after DNA extraction from the cell pellets of the CSF.Results:Five patients showed mutations in one or two actionable genes, two harboured anEGFRmutation (exons 19 and 21), one only aKRASmutation, one bothEGFRandKRASmutations and one aBRAFmutation. In all cases, the results of mutation testing provided new major information for patient management, leading to therapeutic adaptation. CSF molecular analysis identified mutations not detected in other neoplastic sites for two patients. In one case, the EGFR p.Thr790Met was identified. CSF was also the only sample available for genetic testing for almost all patients at the time of disease progression.Conclusions:When cancer cells are present in the CSF, the molecular profiling from the cell pellets is relevant, as it can detect supplemental or different mutations compared to a previous analysis of the primitive tumour or plasma cell-free DNA and allows the adaptation of the treatment strategy.