Codon 12 Ki-ras mutation in non-small-cell lung cancer: comparative evaluation in tumoural and non-tumoural lung

miR-489-3p promotes malignant progression of non-small cell lung cancer through the inactivation of Wnt/β-catenin signaling pathway via regulating USP48

Background

Non-small cell lung cancer (NSCLC) is the most prevalent form of lung cancer globally, with average age of cancer patients becoming younger gradually. It is of significance to gain a comprehensive understanding of molecular mechanism underlying NSCLC.

Methods

Quantitative polymerase chain reaction (qPCR) and western blot were applied to measure RNA and protein levels separately. Functional assays and western blot were performed to determine the effects of miR-489-3p and USP48 on cell growth, migration and epithelial-mesenchymal transition (EMT) in NSCLC. TOP/FOP flash luciferase reporter assay was carried out to detect the activity of Wnt pathway. Besides, qPCR, RNA pulldown and luciferase reporter assays were conducted to probe into the target gene of miR-489-3p. Immunoprecipitation-western blot (IP-western blot) analysis was implemented to assess the effect of USP48 on the ubiquitination of β-catenin.

Results

miR-489-3p hampers NSCLC cell proliferation, migration and EMT in vitro and NSCLC tumorigenesis and metastasis in vivo. Additionally, miR-489-3p inactivates Wnt/β-catenin signaling pathway and regulates USP48 to inhibit the ubiquitination of β-catenin. Moreover, USP48 propels the development of NSCLC cells.

Conclusions

The current study demonstrated that miR-489-3p promotes the malignant progression of NSCLC cells via targeting USP48, which might offer a new perspective into NSCLC treatment.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-01988-w.

KRAS and TP53 mutations in bronchoscopy samples from former lung cancer patients

Mutations in the KRAS and TP53 genes have been found frequently in lung tumors and specimens from individuals at high risk for lung cancer and have been suggested as predictive markers for lung cancer. In order to assess the prognostic value of these two genes' mutations in lung cancer recurrence, we analyzed mutations in codon 12 of the KRAS gene and in hotspot codons of the TP53 gene in 176 bronchial biopsies obtained from 77 former lung cancer patients. Forty-seven patients (61.0%) showed mutations, including 35/77 (45.5%) in the KRAS gene and 25/77 (32.5%) in the TP53 gene, among them 13/77 (16.9%) had mutations in both genes. When grouped according to past or current smoking status, a higher proportion of current smokers showed mutations, in particular those in the TP53 gene (P = 0.07), compared with ex-smokers. These mutations were found in both abnormal lesions (8/20 or 40%) and histologically normal tissues (70/156 or 44.9%) (P = 0.812). They consisted primarily of G to A transition and G to T transversion in both the KRAS (41/56 or 73.2%) and TP53 (24/34 or 70.6%) genes, consistent with mutations found in lung tumors of smoking lung cancer patients. Overall, recurrence-free survival (RFS) among all subjects could be explained by age at diagnosis, tumor stage, tumor subtype, and smoking (P < 0.05, Cox proportional hazard). Therefore, KRAS and TP53 mutations were frequently detected in bronchial tissues of former lung cancer patients. However, the presence of mutation of bronchial biopsies was not significantly associated with a shorter RFS time. © 2016 Wiley Periodicals, Inc.

Smoking history and lung carcinoma: KRAS mutation is an early hit in lung adenocarcinoma development

BACKGROUND

In a European multicenter prospective study patients with lung cancer were interviewed for smoking history and biological samples centrally collected. The aim of this study was to compare KRAS mutation analysis with smoking status at the time of diagnosis.

METHODS

A nested case-study was performed on 233 non-small cell lung carcinomas. Cases were selected on the basis of progressive disease or disease-free post surgery based on specific criteria. KRAS mutation analysis was performed with the point-EXACCT method.

RESULTS

KRAS mutations were found in 39 adenocarcinomas and 1 squamous cell carcinoma in the 233 NSCLC. The median quitting smoking time (QST) for patients with and without KRAS mutations was 9 years, interquartile range [IQR 16-38] and 3 years, IQR [13-50], respectively (p=0.039). No difference was found for age at initiation of smoking, duration of smoking, average tobacco consumption, and smoking status at the time of diagnosis.

CONCLUSION

The QST was longer for patients with KRAS mutations, supporting the notion that the presence of a KRAS mutation is a dominant early effect, supporting its role as a driver oncogen.

Molecular classification and molecular genetics of human lung cancers

Recent advances in the molecular classification of lung carcinomas and the identification of causative genetic alterations will likely lead to improvements in the diagnosis and treatment of patients with lung cancer. It is now possible to identify gene expression profiles that associate with patient outcome in lung carcinomas, in particular adenocarcinoma. Furthermore, patient survival has been shown to correlate with lung cancer oligonucleotide microarray expression profiles. Large-scale microarray technology may allow for the identification of useful biomarkers for early cancer detection. Oligonucleotide microarray data can be optimized by relating them to protein expression levels in tissue microarrays, by annotation with mutational data, and with results of testing for post-translational modification of cellular proteins. These data may be useful in tailoring chemotherapeutic protocols to individual tumors and identifying new targets for therapeutic intervention.

Mapping polycyclic aromatic hydrocarbon and aromatic amine-induced DNA damage in cancer-related genes at the sequence level

Genomic injury induced by environmental carcinogens, such as polycyclic aromatic hydrocarbons and aromatic amines, is the initial step that can trigger mutagenesis and carcinogenesis. In addition to the physico-chemical property of DNA damaging agents, several important factors such as primary sequence, chromatin structure, methylation, protein association, and transcriptional activity can affect not only the initial level and distribution of DNA damage but also the efficiency of repair. Therefore, mapping the DNA damage induced by environmental agents in cancer-related genes such as p53 and ras at the sequence level provides essential information for assessing their carcinogenic potential. Recently, using the E. coli nucleotide excision enzyme complex, UvrABC nucleases in combination with ligation-mediated polymerase chain reaction, we developed a method to map DNA damage in the p53 and ras genes. These studies led us to conclude that targeted DNA damage, in combination with growth selection, contributes greatly in shaping the mutation spectrum in these genes in human cancer. Here we present the rationale and details of this approach, typical experimental results and necessary precautions.

Topographic analysis of K- ras mutations in histologically normal lung tissues and tumours of lung cancer patients

Mutations in the K- ras gene are very common in lung tumours and are implicated in the development of lung cancer, but the timing of their occurrence remains poorly understood. We investigated K- ras mutations in cell samples microdissected by laser capture microscopy at multiple sites from lung tissue sections representing tumour tissue and matched histologically normal tissue obtained from 48 lung cancer patients. K- ras mutations were detected in cell samples from 10 of 38 (26.3%) lung adenocarcinomas and in none of the histologically normal or tumour cell samples taken from 10 lung squamous cell carcinomas. Of the K- ras mutation-positive adenocarcinomas, in 4 cases a mutation was found in only the tumour tissue, in 1 case a mutation was found only in the histologically normal tissue, and in 5 cases mutations were found in both the tumour tissue and histologically normal tissue. Among these 5 cases, 2 had identical mutations in both the tumour tissue and histologically normal tissue, 2 had 1 mutation in the tumour tissue and 2 mutations in the histologically normal tissue, 1 of which was identical to the mutation found in the tumour, and 1 case had 2 codon 12 mutations in tumour tissue and 2 mutations, in codons 9 and 11, in histologically normal tissue. These results showed that K- ras mutations are frequent in histologically normal cells taken from outside lung adenocarcinomas and suggest that some of these mutations may represent early events which could pave the way of lung carcinogenesis.

Detection of codon 12 K-ras mutations in non-neoplastic mucosa from bronchial carina in patients with lung adenocarcinomas

K-ras activation by point mutation in codon 12 has been reported in lung adenocarcinomas in various models of experimental lung tumours induced by chemical carcinogens. The hypothesis of the presence of cells containing K-ras mutation in non neoplastic bronchial carina, the main site of impaction of airborne contaminants, was investigated by evaluating concurrent lung tumour and non-neoplastic proximal bronchial carinae from 19 patients with lung adenocarcinomas. The restriction fragment length polymorphism enriched PCR method used can detect one mutant allele among 10(3) normal alleles. A mutation was detected in 42% of lung adenocarcinoma samples. No mutation was detected in either tumour or bronchial carinae in nine patients (47%). K-ras mutation was detected in the lung tumour but not in bronchial carinae in four patients (21%), in both the lung tumour and bronchial carinae in four other patients (21%). In two patients (11%), K-ras mutation was detected in at least one bronchial carina, but not in the lung tumour. Mutations of codon 12, confirmed by sequencing analysis of ten samples, were G to T transversion, mostly TGT and GTT in bronchial carinae and lung tumours. Our data show that activated K-ras by point mutation can be present in non-neoplastic bronchial carina mucosa even when no mutation is detected in tumour samples.

Protein expression and genetic alterations of p53 and ras in intrahepatic cholangiocarcinoma

AIMS

The significance of molecular and genetic alterations of p53 and ras in the development and progression as well as the histological differentiation of intrahepatic cholangiocarcinoma (ICC) was evaluated.

METHODS AND RESULTS

We examined immunohistochemically ras p21 protein and p53-related products (p53 protein, WAF-1 and mdm-2) in 43 cases of ICC. In addition, point mutations of ras and p53 were examined genetically in selected ICC cases by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequence analysis. Point mutation of K-ras gene codon 12 was detected in three of 14 cases and one of 15 cases by PCR-RFLP and direct sequence analysis, respectively. Immunoreactivity of ras p21 protein was not detected. Point mutation of p53 was detected in three of 15 cases. p53 protein was immunohistochemically detectable in 33 of 43 cases. Immunoreactivity of p53 was more frequent in well-differentiated and less frequent in poorly differentiated cases. Immunoreactivity of WAF-1 and mdm-2 was seen in 16 and eight of 43 cases, respectively. Both proteins were frequently detected in the cases positive for p53 protein.

CONCLUSION

These results suggest that dysregulation of ras is involved in at least 20% of ICC and expression of p53 protein is more significantly involved in ICC, particularly in the well and moderately differentiated cases. While some cases of p53 expression may be explainable by point mutation of p53, there may be some epigenetic phenomena that stabilize p53 protein in ICC. That is, wild type p53 may be stabilized and then detectable by forming complexes with other molecules of p53 downstream effector genes, such as WAF-1 and mdm-2.

K-ras gene point mutation in neogenetic lesions of subpleural fibrotic lesions: either an early genetic event in lung cancer development or a non-specific genetic change during the inflammatory reparative process

In the present study, K-ras mutation was investigated in 156 neogenetic epithelia that appeared in the lesion of subpleural fibrosis in order to elucidate the close relationship of lung cancer development with pulmonary interstitial pneumonia. The neogenetic epithelia were histologically subclassified into six types: (i) ciliated bronchial epithelium (CBE); (ii) squamous metaplastic epithelium (SME); (iii) cuboidal immature epithelium (CIE); (iv) stratified immature epithelium (SIE); (v) mucus cell epithelium (MCE); and (vi) intestinal metaplastic epithelium (IME). K-ras mutation was detected in 9.6% of neogenetic epithelia overall; 21% of CIE, 12% of SIE, 16% of SME, but not in other types of neogenetic epithelia. Immunohistochemically, CIE and SIE frequently expressed surfactant apoprotein and SME was characteristic to carcinoembryonic antigen expression. According to Ki-67 immunostain, CIE, SIE and SME are likely to grow faster than other histological types of epithelia. K-ras mutation was seen exclusively in codon 12 with predominant G to A and G to C substitutions without any G to T transversions, results which are somewhat different to previous studies in lung cancers. The present study clearly demonstrated that K-ras mutation appeared in certain histological types of neogenetic epithelia, but raised the question of whether K-ras mutation in neogenetic epithelia during the inflammatory reparative process might be an early genetic event in lung carcinogenesis.

Environmental factors as regulators and effectors of multistep carcinogenesis

This review highlights current knowledge of environmental factors in carcinogenesis and their cellular targets. The hypothesis that environmental factors influence carcinogenesis is widely supported by both epidemiological and experimental studies. The fact that only a small fraction of cancers can be attributed to germline mutations in cancer-related genes further buttresses the importance of environmental factors in carcinogenesis. Furthermore, penetrance of germline mutations may be modified by either environmental or other genetic factors. Examples of environmental factors that have been associated with increased cancer risk in the human population include chemical and physical mutagens (e.g. cigarette smoke, heterocyclic amines, asbestos and UV irradiation), infection by certain viral or bacterial pathogens, and dietary non-genotoxic constituents (e.g. macro- and micronutrients). Among molecular targets of environmental influences on carcinogenesis are somatic mutation (genetic change) and aberrant DNA methylation (epigenetic change) at the genomic level and post-translational modifications at the protein level. At both levels, changes elicited affect either the stability or the activity of key regulatory proteins, including oncoproteins and tumor suppressor proteins. Together, via multiple genetic and epigenetic lesions, environmental factors modulate important changes in the pathway of cellular carcinogenesis.