Kirsten ras mutations in patients with colorectal cancer: the 'RASCAL II' study

KRAS G12V mutation-selective requirement for ACSS2 in colorectal adenoma formation

Oncogenic KRAS mutations are prevalent in colorectal cancer (CRC) and linked to poor prognosis and therapeutic resistance. Emerging evidence suggests that specific KRAS mutations differentially influence treatment responses. In this study, we generate isogenic Apc-null mouse colon epithelial cells with four common KRAS mutations. Transcriptomic and proteomic analyses reveal significant enrichment of cholesterol and lipid metabolism pathways in KRAS G12V cells, driven by increased SREBP1 expression and mTORC1 activation. Furthermore, KRAS G12V cells exhibit elevated ACSS2 expression and greater dependence on ACSS2 for proliferative advantage compared to other mutants. Inhibition of ACSS2 uniquely sensitizes KRAS G12V cells to MEK inhibition, highlighting a distinct therapeutic vulnerability. Finally, ACSS2 plays a critical role in early KRAS G12V adenoma development, unlike in KRAS G12D adenomas. These findings highlight mutation-specific metabolic reprogramming in KRAS-driven CRC and identify ACSS2 as a potential therapeutic target.

The impact of KRAS mutations on risk of venous thromboembolism recurrence in patients with metastatic colorectal cancer

BACKGROUND

The relationship between KRAS mutations and the risk of venous thromboembolism (VTE) recurrence in metastatic colorectal cancer (mCRC) patients with established cancer-associated thrombosis (CAT) remains uncertain. This study aims to (1) evaluate the predictive value of seven KRAS mutation subtypes for VTE recurrence and (2) assess the impact of incorporating these mutations into two existing VTE risk scores: the Khorana score and the Ottawa score.

METHODS

Between 2019 and 2023, we identified patients with histologically confirmed mCRC who had symptomatic or incidental index VTE and received anticoagulation therapy. Regression analyses were conducted to calculate hazard ratios (HRs) for recurrent VTE associated with the seven KRAS mutation subtypes. We used receiver operating characteristic (ROC) curves to assess the performance of both the original scores and the modified scores that included KRAS mutations. To quantify the improvements of the modified scores, we calculated the net reclassification improvement (NRI).

RESULTS

A total of 2,195 patients were enrolled. KRAS G12C, KRAS G12A, and KRAS G13D mutations were significantly associated with a higher risk of recurrent VTE compared to other subtypes, with HRs of 1.84 (95% CI: 1.09-2.97), 2.02 (95% CI: 1.07-3.79), and 1.55 (95% CI: 1.02-2.27), respectively. The original Khorana and Ottawa scores demonstrated moderate predictive ability for VTE recurrence, each with an area under the ROC curve (ROC-AUC) of 0.56 (95% CI: 0.52-0.60). Incorporating the KRAS G12C, KRAS G12A, and KRAS G13D mutations improved the AUCs to 0.70 (95% CI: 0.67-0.74) for the modified Khorana score and 0.71 (95% CI: 0.67-0.74) for the modified Ottawa score. After dichotomizing risk using thresholds from ROC analysis, the NRI values were 0.54 (95% CI: 0.43-0.65) for the modified Khorana score and 0.48 (95% CI: 0.37-0.60) for the modified Ottawa score.

CONCLUSIONS

The KRAS G12C, KRAS G12A, and KRAS G13D mutations are significantly associated with an increased risk of recurrent VTE. Incorporating these specific KRAS mutations into existing risk scores may enhance their predictive accuracy for recurrent VTE in patients with mCRC.

Associations of KRAS Point Mutations with Survival of Patients Who Underwent Curative-Intent Resection of Colorectal Liver Metastases

BACKGROUND

The oncologic significance of specific KRAS point mutations for patients with colorectal liver metastases (CLM) is uncertain. This study aimed to assess the prognostic impact of KRAS point mutations on patients who underwent surgery for CLM.

METHODS

Patients who underwent curative-intent surgery for CLM from 2001 to 2020 were selected for the study. In the study, KRAS point mutations and other clinicopathologic variables were examined for association with survival.

RESULTS

The study classified 798 patients into five groups by KRAS mutation status as follows: wild-type (n = 412, 51.6%), G12D (n = 123, 15.4%), G12V (n = 88, 11.0%), G13D (n = 61, 7.6%), and "Other" mutations (n = 114, 14.3%). For the patients with G12V substitutions, TP53 mutation was associated with worse overall survival (OS) (hazard ratio [HR], 2.64; 95% confidence interval [CI], 1.04-6.66; P = 0.041), but was not associated with a survival difference for the other four groups. The patients with co-occurring KRAS G12V and TP53 had a median OS of 4.4 years and a 5-year OS rate of 39.8%. In contrast, the patients with KRAS G12V mutation and wild-type TP53 had a median OS of 7.3 years and a 5-year OS rate of 75.9%, similar to the corresponding values for the patients with wild-type KRAS. Co-occurring KRAS G12V and TP53 mutations were independently associated with worse OS in the entire cohort (HR, 2.08; 95% CI, 1.15-3.76; P = 0.015).

CONCLUSIONS

This study showed that KRAS G12V mutation is associated with worse OS for patients undergoing curative-intent CLM resection, but only those with co-occurring TP53 mutation. Prognosis after surgery for CLM should not be stratified by KRAS mutation site alone.

Inhibitors of oncogenic Kras specifically prime CTLA4 blockade to transcriptionally reprogram Tregs and overcome resistance to suppress pancreas cancer

Lack of sustained response to oncogenic Kras (Kras*) inhibition in preclinical models and patients with pancreatic ductal adenocarcinoma (PDAC) emphasizes the need to identify impactful synergistic combination therapies to achieve robust clinical benefit. Kras* targeting results in an influx of global T cell infiltrates including Tregs, effector CD8 + T cells and exhausted CD8 + T cells expressing several immune checkpoint molecules in PDAC. Here, we probe whether the T cell influx induced by diverse Kras* inhibitors open a therapeutic window to target the adaptive immune response in PDAC. We show a specific synergy of anti-CTLA4 immune checkpoint blockade with Kras* targeting primed by Kras G12D allele specific inhibitor, MRTX1133 and multi-selective pan-RAS inhibitor, RMC-6236, both currently in clinical testing phase. In contrast, attempted therapeutic combination following Kras* targeting with multiple checkpoint inhibitors, including anti-PD1, anti-Tim3, anti-Lag3, anti-Vista and anti-4-1BB agonist antibody failed due to compensatory mechanisms mediated by other checkpoints on exhausted CD8 + T cells. Anti-CTLA4 therapy in Kras* targeted PDAC transcriptionally reprograms effector T regs to a naïve phenotype, reverses CD8 + T cell exhaustion and is associated with recruitment of tertiary lymphoid structures (TLS) containing interferon (IFN)-stimulated/ activated B cells and germinal center B cells to enable immunotherapy efficacy and overcome resistance with long-term survival. Single cell ATAC sequencing analysis revealed that transcriptional reprogramming of Tregs is epigenetically regulated by downregulation of AP-1 family of transcription factors including Fos, Fos-b, Jun-b, Jun-d in the IL-35 promoter region. This study reveals an actionable vulnerability in the adaptive immune response in Kras* targeted PDAC with important clinical implications.

Graphical abstract

A Narrative Review of RAS Mutations in Early-Stage Colorectal Cancer: Mechanisms and Clinical Implications

Colorectal cancer (CRC) is the third-most common cancer globally and a leading cause of cancer-related deaths. While the prognostic and predictive roles of RAS mutations in advanced CRC are well-established, their significance in early-stage CRC remains a topic of debate. Studies have been conducted for many years on clinical and pathological parameters that may be associated with RAS mutation, and there are inconsistent results in this regard. Currently, the only biomarker used in early-stage CRC is microsatellite status. KRAS mutations are detected in 40-50% of patients with colorectal cancer. RAS activating mutations cause loss of EGFR regulation by acting on the RAS/RAF/MAPK signaling pathways. In advanced colorectal cancer, these mechanisms cause a decrease in the effectiveness of EGFR inhibitors. However, studies on patients with early-stage colorectal cancer have inconsistent results. This review highlights the prognostic and clinical significance of KRAS mutations in early-stage CRC, particularly in MSS tumors. In the MSS group, KRAS mutations were associated with shorter TTR and OS compared to DWT patients. In contrast, in the MSI-H group, KRAS mutations showed no prognostic effect in TTR and OS. However. KRAS mutations were associated with shorter SAR in both MSI-H and MSS groups of patients. The findings underscore the need for routine molecular profiling, including KRAS and MSI status, to refine risk stratification and guide adjuvant therapy decisions. Further studies are warranted to explore targeted therapeutic approaches for KRAS-mutant CRC in the adjuvant setting.

Second-line systemic treatment for metastatic colorectal cancer: A systematic review and Bayesian network meta-analysis based on RCT

BACKGROUND

The optimal second-line systemic treatment for metastatic colorectal cancer (mCRC) is inconclusive.

METHODS

We searched PubMed, Web of Science, EMBASE, and Cochrane Library for RCTs comparing second-line systemic treatments for mCRC from the inception of each database up to February 3, 2024. Markov Chain Monte Carlo (MCMC) technique was used in this network meta-analysis (NMA) to generate the direct and indirect comparison results among multiple treatments in progression-free survival (PFS), overall response rate (ORR), overall survival (OS), complete response (CR), partial response (PR), grade 3 and above adverse events (Grade ≥ 3AE), and any adverse events (Any AE). The surface under the cumulative ranking curve (SUCRA) was adopted to evaluate the probability of each treatment being the optimum intervention. Subgroup analyses were performed based on the RAS gene status.

RESULTS

A total of 47 randomized controlled trials were included, involving 16,925 patients and 44 second-line systemic treatments. In improving OS, FOLFOX + Bevacizumab + Erlotinib exhibited significant superiority (SUCRA:92.7%). In improving PFS, Irinotecan + CMAB009 (SUCRA:86.4%) had advantages over other treatments. FOLFIRI + Trebananib (SUCRA:88.1%) had a significant advantage in improving ORR. Among multiple second-line treatments, the SUCRA values of FOLFOX + Bevacizumab in PFS, OS, ORR, and PR were 83.4%, 74.0%, 81.1%, and 86.1%, respectively, and the safety was not significantly different from other interventions. Subgroup analyses showed that FOLFIRI + Bevacizumab + panitumumab ranked among the top in survival outcomes in the RAS-mutant population (OS SUCRA: 87.9%; PFS SUCRA: 70.2%); whereas in the RAS-wild-type population, FOLFIRI + Bevacizumab significantly improved survival outcomes (OS SUCRA: 73.2%; PFS SUCRA: 65.1%).

CONCLUSION

For most people, FOLFOX + Bevacizumab may be the best second-line systemic treatment regimen for mCRC. For RAS-mutant populations, FOLFIRI + Bevacizumab + Panitumumab is recommended. However, the therapeutic effect may be affected by the patient's physiological state, and clinicians should apply it based on actual conditions.

The Potential of Metabolomics in Colorectal Cancer Prognosis

Colorectal cancer (CRC) is one of the most common cancers worldwide, posing a serious threat to human health. Metabolic reprogramming represents a critical feature in the process of tumor development and progression, encompassing alterations in sugar metabolism, lipid metabolism, amino acid metabolism, and other pathways. Metabolites hold promise as innovative prognostic biomarkers for cancer patients, which is crucial for targeted follow-up care and interventions. This review aims to provide an overview of the progress in research on metabolic biomarkers for predicting the prognosis of CRC. We also discuss the future trends and challenges in this area.

Unlocking the Power of Multi-institutional Data: Integrating and Harmonizing Genomic Data Across Institutions

Cancer is a complex disease driven by genomic alterations, and tumor sequencing is becoming a mainstay of clinical care for cancer patients. The emergence of multi-institution sequencing data presents a powerful resource for learning real-world evidence to enhance precision oncology. GENIE BPC, led by American Association for Cancer Research, establishes a unique database linking genomic data with clinical information for patients treated at multiple cancer centers. However, leveraging sequencing data from multiple institutions presents significant challenges. Variability in gene panels can lead to loss of information when analyses focus on genes common across panels. Additionally, differences in sequencing techniques and patient heterogeneity across institutions add complexity. High data dimensionality, sparse gene mutation patterns, and weak signals at the individual gene level further complicate matters. Motivated by these real-world challenges, we introduce the Bridge model. It uses a quantile-matched latent variable approach to derive integrated features to preserve information beyond common genes and maximize the utilization of all available data, while leveraging information sharing to enhance both learning efficiency and the model's capacity to generalize. By extracting harmonized and noise-reduced lower-dimensional latent variables, the true mutation pattern unique to each individual is captured. We assess model's performance and parameter estimation through extensive simulation studies. The extracted latent features from the Bridge model consistently excel in predicting patient survival across six cancer types in GENIE BPC data.

Unlocking the power of multi-institutional data: Integrating and harmonizing genomic data across institutions

Cancer is a complex disease driven by genomic alterations, and tumor sequencing is becoming a mainstay of clinical care for cancer patients. The emergence of multi-institution sequencing data presents a powerful resource for learning real-world evidence to enhance precision oncology. GENIE BPC, led by American Association for Cancer Research, establishes a unique database linking genomic data with clinical information for patients treated at multiple cancer centers. However, leveraging sequencing data from multiple institutions presents significant challenges. Variability in gene panels can lead to loss of information when analyses focus on genes common across panels. Additionally, differences in sequencing techniques and patient heterogeneity across institutions add complexity. High data dimensionality, sparse gene mutation patterns, and weak signals at the individual gene level further complicate matters. Motivated by these real-world challenges, we introduce the Bridge model. It uses a quantile-matched latent variable approach to derive integrated features to preserve information beyond common genes and maximize the utilization of all available data, while leveraging information sharing to enhance both learning efficiency and the model's capacity to generalize. By extracting harmonized and noise-reduced lower-dimensional latent variables, the true mutation pattern unique to each individual is captured. We assess model's performance and parameter estimation through extensive simulation studies. The extracted latent features from the Bridge model consistently excel in predicting patient survival across six cancer types in GENIE BPC data.

Combining KRAS gene status with preoperative D‑dimer levels as a predictive marker of venous thromboembolism risk in patients with resectable colorectal cancer: A prospective cohort study

Colorectal cancer (CRC), one of the most prevalent types of cancer, is accompanied by a notably high incidence of thrombotic complications. The present study aimed to elucidate the association between KRAS mutations and hypercoagulability in operable CRC. The prognostic value of preoperative D-dimer levels was also investigated, thus providing novel insights into the development of therapeutic strategies to enhance patient survival and diminish morbidity. Therefore, a prospective analysis of 333 CRC cases post-surgery at Yan'an Hospital Affiliated to Kunming Medical University, between May 2019 and October 2022 was performed. Data on demographics, tumor characteristics and D-dimer levels were compiled from the electronic health records. Venous thromboembolism (VTE) was diagnosed by doppler or computed tomography angiography, with D-dimer thresholds set at 550 and 1,650 µg/l. KRAS mutations at codons 12 and 13 were assessed in a subset of 56 cases. Subsequently, the factors affecting the hypercoagulable state in these patients were prospectively analyzed, focusing on the pivotal role of KRAS. The results showed that KRAS mutations were associated with elevated preoperative D-dimer levels, with 1,076 µg/l compared with 485 µg/l in the wild-type cohort, indicative of a hypercoagulable state. Increased D-dimer levels were also associated with vascular invasion, distant metastases and a heightened risk of postoperative VTE. Furthermore, multivariate analyses identified KRAS mutations, distant metastases and vascular invasion as independent predictors of elevated D-dimer levels, with relative risk values of 2.912, 1.884 and 1.525, respectively. Conversely, sex, age, tumor location, differentiation grade, Ki67 index and tumor stage could not significantly affect D-dimer levels, thus indicating a complex interplay between tumor genetics and coagulation dysfunction in CRC. The current study suggested that the KRAS mutation status, distant metastasis and vascular invasion could be considered as independent risk factors of blood hypercoagulability in patients with CRC, potentially serving as prognostic factors for VTE risk.

Transglutaminase 2 serves as a pathogenic hub gene of KRAS mutant colon cancer based on integrated analysis

BACKGROUND

Colon cancer is acknowledged as one of the most common malignancies worldwide, ranking third in United States regarding incidence and mortality. Notably, approximately 40% of colon cancer cases harbor oncogenic KRAS mutations, resulting in the continuous activation of epidermal growth factor receptor signaling.

AIM

To investigate the key pathogenic genes in KRAS mutant colon cancer holds considerable importance.

METHODS

Weighted gene co-expression network analysis, in combination with additional bioinformatics analysis, were conducted to screen the key factors driving the progression of KRAS mutant colon cancer. Meanwhile, various in vitro experiments were also conducted to explore the biological function of transglutaminase 2 (TGM2).

RESULTS

Integrated analysis demonstrated that TGM2 acted as an independent prognostic factor for progression-free survival. Immunohistochemical analysis on tissue microarrays revealed that TGM2 was associated with an elevated probability of perineural invasion in patients with KRAS mutant colon cancer. Additionally, biological roles of the key gene TGM2 was also assessed, suggesting that the downregulation of TGM2 attenuated the proliferation, invasion, and migration of the KRAS mutant colon cancer cell line.

CONCLUSION

This study underscores the potential significance of TGM2 in the progression of KRAS mutant colon cancer. This insight not only offers a theoretical foundation for therapeutic approaches but also highlights the need for additional clinical trials and fundamental research to support our preliminary findings.

Biological and targeting differences between the rare KRAS A146T and canonical KRAS mutants in gastric cancer models

BACKGROUND

Gastric cancer (GC) is the third leading cause of cancer-related death worldwide, with a poor prognosis for patients with advanced disease. Since the oncogenic role of KRAS mutants has been poorly investigated in GC, this study aims to biochemically and biologically characterize different KRAS-mutated models and unravel differences among KRAS mutants in response to therapy.

METHODS

Taking advantage of a proprietary, molecularly annotated platform of more than 200 GC PDXs (patient-derived xenografts), we identified KRAS-mutated PDXs, from which primary cell lines were established. The different mutants were challenged with KRAS downstream inhibitors in in vitro and in vivo experiments.

RESULTS

Cells expressing the rare KRAS A146T mutant showed lower RAS-GTP levels compared to those bearing the canonical G12/13D mutations. Nevertheless, all the KRAS-mutated cells displayed KRAS addiction. Surprisingly, even if the GEF SOS1 is considered critical for the activation of KRAS A146T mutants, its abrogation did not significantly affect cell viability. From the pharmacologic point of view, Trametinib monotherapy was more effective in A146T than in G12D-mutated models, suggesting a vulnerability to MEK inhibition. However, in the presence of mutations in the PI3K pathway, more frequently co-occurrent in A146T models, the association of Trametinib and the AKT inhibitor MK-2206 was required to optimize the response.

CONCLUSION

A deeper genomic and biological characterization of KRAS mutants might sustain the development of more efficient and long-lasting therapeutic options for patients harbouring KRAS-driven GC.

Exploring the multifaceted role of RASGRP1 in disease: immune, neural, metabolic, and oncogenic perspectives

RAS guanyl releasing protein 1 (RASGRP1) is a guanine nucleotide exchange factor (GEF) characterized by the presence of a RAS superfamily GEF domain. It functions as a diacylglycerol (DAG)-regulated nucleotide exchange factor, specifically activating RAS through the exchange of bound GDP for GTP. Activation of RAS by RASGRP1 has a wide range of downstream effects at the cellular level. Thus, it is not surprising that many diseases are associated with RASGRP1 disorders. Here, we present an overview of the structure and function of RASGRP1, its crucial role in the development, expression, and regulation of immune cells, and its involvement in various signaling pathways. This review comprehensively explores the relationship between RASGRP1 and various diseases, elucidates the underlying molecular mechanisms of RASGRP1 in each disease, and identifies potential therapeutic targets. This study provides novel insights into the role of RASGRP1 in insulin secretion and highlights its potential as a therapeutic target for diabetes. The limitations and challenges associated with studying RASGRP1 in disease are also discussed.

KRAS mutation-selective requirement for ACSS2 in colorectal adenoma formation

Oncogenic KRAS mutations are prevalent in colorectal cancer (CRC) and are associated with poor prognosis and resistance to therapy. There is a substantial diversity of KRAS mutant alleles observed in CRC. Emerging clinical and experimental analysis of common KRAS mutations suggest that each mutation differently influences the clinical properties of a disease and response to therapy. Although there is some evidence to suggest biological differences between mutant KRAS alleles, these are yet to be fully elucidated. One approach to study allelic variation involves the use of isogenic cell lines that express different endogenous Kras mutants. Here, we generated Kras isogenic Apc-/- mouse colon epithelial cell lines using CRISPR-driven genome editing by altering the original G12D Kras allele to G12V, G12R, or G13D. We utilized these cell lines to perform transcriptomic and proteomic analysis to compare different signaling properties between these mutants. Both screens indicate significant differences in pathways relating to cholesterol and lipid regulation that we validated with targeted metabolomic measurements and isotope tracing. We found that these processes are upregulated in G12V lines through increased expression of nuclear SREBP1 and higher activation of mTORC1. G12V cells showed higher expression of ACSS2 and ACSS2 inhibition sensitized G12V cells to MEK inhibition. Finally, we found that ACSS2 plays a crucial role early in the development of G12V mutant tumors, in contrast to G12D mutant tumors. These observations highlight differences between KRAS mutant cell lines in their signaling properties. Further exploration of these pathways may prove to be valuable for understanding how specific KRAS mutants function, and identification of novel therapeutic opportunities in CRC.

KRAS-mutant colorectal cancer cell lines cause a prothrombotic state through the upregulation of thrombin: experimental study

Background

The KRAS genotype status is strongly associated with a prothrombotic state in colorectal cancer, and hypercoagulability and cancer-related thrombosis are among the significant events leading to poor prognosis. However, this correlation has not been confirmed at the cellular level. This study aimed to assess the maximum platelet aggregation rate and thrombin expression induced by colorectal cancer cells under different KRAS genotypes.

Materials and methods

Platelet aggregation rate assay and western blotting analysis were used to detect platelet aggregation and thrombin expression induced by four colorectal cancer cells with different KRAS genotypes, including RKO, HCT116, SW480, and SW620. FVIIa/tissue factor and thrombin inhibitors were added to explore changes in platelet aggregation rates induced by colorectal cancer cells and the association between KRAS genotype status and hypercoagulable state.

Results

KRAS-mutant cells were more likely to increase maximal platelet aggregation, with RKO, HCT116, SW480, and SW620 inducing 34.7%, 55.4%, 44.4%, and 63.8% of platelet aggregation, respectively. The maximum platelet aggregation rate was higher in the metastatic rectal cancer tumour strain SW620 than in the primary rectal cancer strain SW480. RKO cells had lower thrombin expression than the other three cells. Furthermore, the addition of thrombin inhibitors caused a more significant decrease in the platelet aggregation rate in KRAS-mutant cell lines compared to KRAS wild-type cell lines.

Conclusion

Compared to KRAS wild-type colorectal cancer cells, KRAS-mutant colorectal cancer cell lines were more likely to be hypercoagulable through the upregulation of thrombin expression, which was mainly achieved through the TF-thrombin pathway.

ERK2 Is a Promoter of Cancer Cell Growth and Migration in Colon Adenocarcinoma

ERK1/2 phosphorylation is frequently downregulated in the early phase of colon tumorigenesis with subsequent activation of ERK5. In the current work, we studied the advantages of ERK1/2 downregulation for tumor growth by dissecting the individual functions of ERK1 and ERK2. The patient sample data demonstrated decreased ERK1/2 phosphorylation in the early phase of tumorigenesis followed by increased phosphorylation in late-stage colon adenocarcinomas with intratumoral invasion or metastasis. In vitro results indicated that SOD3-mediated coordination of small GTPase RAS regulatory genes inhibited RAS-ERK1/2 signaling. In vitro and in vivo studies suggested that ERK2 has a more prominent role in chemotactic invasion, collective migration, and cell proliferation than ERK1. Of note, simultaneous ERK1 and ERK2 expression inhibited collective cell migration and proliferation but tended to promote invasion, suggesting that ERK1 controls ERK2 function. According to the present data, phosphorylated ERK1/2 at the early phase of colon adenocarcinoma limits tumor mass expansion, whereas reactivation of the kinases at the later phase of colon carcinogenesis is associated with the initiation of metastasis. Additionally, our results suggest that ERK1 is a regulatory kinase that coordinates ERK2-promoted chemotactic invasion, collective migration, and cell proliferation. Our findings indicate that ROS, especially H2O2, are associated with the regulation of ERK1/2 phosphorylation in colon cancer by either increasing or decreasing kinase activity. These data suggest that ERK2 has a growth-promoting role and ERK1 has a regulatory role in colon tumorigenesis, which could lead to new avenues in the development of cancer therapy.

Correlation Between DCAMKL-1 Protein Expression and K-ras Gene Mutation in Colorectal Cancer

Aim

To investigate the correlation between doublecortin and CaM kinase-like-1 (DCAMKL-1) protein expression, K-ras gene mutation, and their impact on patient prognosis in colorectal cancer (CRC).

Methods

Immunohistochemistry was used to detect the expression of DCAMKL-1 protein in 60 cases of colorectal adenoma, 82 cases of CRC (including 65 cases of lymph node metastasis) and paraffin-embedded paracancerous intestinal mucosal tissue. K-ras gene mutations in primary CRC lesions were detected using an amplification-refractory mutation system and fluorescent polymerase chain reaction. The relationship between DCAMKL-1 protein expression and K-ras gene mutations with the clinicopathological characteristics of patients with CRC was analyzed. Univariate Kaplan‒Meier survival analysis and multivariate Cox regression analysis were performed using follow-up data.

Results

The mutation rate of the K-ras gene in 82 cases of CRC was 48.8% (40/82). The positivity rate for the presence of DCAMKL-1 protein in CRC was 70.7% (58/82), significantly higher than that for colorectal adenomas (53.3%; 32/60) and paracancerous intestinal mucosa (0%; 0/82) (P<0.05). The positive expression rate for the presence of DCAMKL-1 protein in 65 patients with lymph node metastasis was higher in the primary lesions (69.2%; 45/65) than in the lymph node metastases (52.3%; 34/65) (χ2=12.087, P=0.001). The K-ras gene mutation status was positively correlated with DCAMKL-1 protein expression (r=0.252, P=0.022).

Conclusion

In this study, a potential positive correlation between K-ras gene mutation and DCAMKL-1 protein expression was identified in CRC tissues. The assessment of K-ras gene mutation status and DCAMKL-1 protein expression holds promise for augmenting early diagnosis and prognosis evaluation in CRC. This approach may improve the overall prognosis and survival outcomes for CRC patients.

Gastrointestinal Malignancy: Genetic Implications to Clinical Applications

Advances in molecular genetics have revolutionized our understanding of the pathogenesis, progression, and therapeutic options for treating gastrointestinal (GI) cancers. This chapter provides a comprehensive overview of the molecular landscape of GI cancers, focusing on key genetic alterations implicated in tumorigenesis across various anatomical sites including GIST, colon and rectum, and pancreas. Emphasis is placed on critical oncogenic pathways, such as mutations in tumor suppressor genes, oncogenes, chromosomal instability, microsatellite instability, and epigenetic modifications. The role of molecular biomarkers in predicting prognosis, guiding treatment decisions, and monitoring therapeutic response is discussed, highlighting the integration of genomic profiling into clinical practice. Finally, we address the evolving landscape of precision oncology in GI cancers, considering targeted therapies and immunotherapies.

Leveraging a KRAS-based signature to predict the prognosis and drug sensitivity of colon cancer and identifying SPINK4 as a new biomarker

KRAS is one of the leading mutations reported in colon cancer. However, there are few studies on the application of KRAS related signature in predicting prognosis and drug sensitivity of colon cancer patient. We identified KRAS related differentially expressed genes (DEGs) using The Cancer Genome Atlas (TCGA) database. A signature closely related to overall survival was recognized with Kaplan-Meier survival analysis and univariate cox regression analysis. Then we validated this signature with overall expression score (OE score) algorithm using both scRNA-seq and bulk RNA-seq data. Based on this signature, we performed LASSO cox regression to establish a prognostic model, and corresponding scores were calculated. Differences in genomic alteration, immune microenvironment, drug sensitivity between high- and low-KRD score groups were investigated. A KRAS related signature composed of 80 DEGs in colon cancer were recognized, among which 19 genes were selected to construct a prognostic model. This KRAS related signature was significantly correlated with worse prognosis. Furthermore, patients who scored lower in the prognostic model presented a higher likelihood of responding to chemotherapy, targeted therapy and immunotherapy. Furthermore, among the 19 selected genes in the model, SPINK4 was identified as an independent prognostic biomarker. Further validation in vitro indicated the knockdown of SPINK4 promoted the proliferation and migration of SW48 cells. In conclusion, a novel KRAS related signature was identified and validated based on clinical and genomic information from TCGA and GEO databases. The signature was proved to regulate genomic alteration, immune microenvironment and drug sensitivity in colon cancer, and thus might serve as a predictor for individual prognosis and treatment.

Selecting Optimal First-Line Treatment for Microsatellite Stable and Non-Mutated RAS/BRAF Metastatic Colorectal Cancer

OPINION STATEMENT

Standard frontline treatment of metastatic colorectal cancer (CRC) is cytotoxic chemotherapy plus a biologic agent such as an anti-EGFR monoclonal antibody (cetuximab or panitumumab) or anti-VEGF antibody (bevacizumab). Predictive biomarkers include mismatch repair (MMR) status, and RAS and BRAF mutation status; and important factors in treatment selection include primary tumor location, intent of therapy, and potential toxicity, as well as patient age, comorbidities, and patient preference. To date, single-, double-, or triple-agent cytotoxic chemotherapy all have important roles in appropriately selected patients, with the addition of anti-VEGF or anti-EGFR antibody therapy based on the relevant predictive biomarker. Data indicate that patients with proficient MMR, RAS/BRAF wt mCRC are candidates for an anti-EGFR antibody plus doublet chemotherapy if they have a left-sided primary tumor, or for anti-VEGF (bevacizumab) plus doublet or triplet chemotherapy if they have a right-sided primary tumor. Future studies may provide more predictive biomarkers to further personalize therapy for this heterogeneous disease.

KRAS Sequence Variation as Prognostic Marker in Patients With Young- vs Late-Onset Colorectal Cancer

Importance

The understanding of the association between KRAS sequence variation status and clinical outcomes in colorectal cancer (CRC) has evolved over time.

Objective

To characterize the association of age at onset, tumor sidedness, and KRAS sequence variation with survival among patients diagnosed with CRC.

Design, Setting, and Participants

This cross-sectional study used data extracted from the Surveillance, Epidemiology, and End Results database. Patients diagnosed with adenocarcinoma of the colon or rectum from 2010 through 2015 were included and were classified as having young-onset (YO) cancer if diagnosed between ages 20 to 49 years and late-onset (LO) cancer if diagnosed at age 50 years or older. Data were analyzed from April 2021 through August 2023.

Main Outcomes and Measures

CRC cause-specific survival (CSS) was summarized using Fine and Gray cumulative incidence and Kaplan-Meier curves. Estimation of subdistribution hazard ratios (sHRs) for the association of KRAS status, age at onset, and tumor location with CRC CSS was conducted using the Fine and Gray competing risk model. Cox proportional hazards regression was used to estimate and compare HRs.

Results

Among 21 661 patients with KRAS sequence variation status (mean [SD] age at diagnosis, 62.50 [13.78] years; 9784 females [45.2%]), 3842 patients had YO CRC, including 1546 patients with KRAS variants, and 17 819 patients had LO CRC, including 7311 patients with KRAS variants. There was a significant difference in median CSS time between patients with variant vs wild-type KRAS (YO: 3.0 years [95% CI, 2.8-3.3 years] vs 3.5 years [95% CI, 3.3-3.9 years]; P = .02; LO: 2.5 years [95% CI, 2.4-2.7 years] vs 3.4 years [95% CI, 3.3-3.6 years]; P < .001). Tumors with variant compared with wild-type KRAS were associated with higher risk of CRC-related death (YO: sHR, 1.09 [95% CI, 1.01-1.18]; P = .03; LO: sHR, 1.06 [95% CI, 1.02-1.09]; P = .002). Among patients with YO cancer, mortality hazards increased by location, from right (sHR, 1.02 [95% CI, 0.88-1.17) to left (sHR, 1.15 [95% CI, 1.02-1.29) and rectum (sHR, 1.16 [95% CI, 0.99-1.36), but no trend by tumor location was seen for LO cancer.

Conclusions and Relevance

In this study of patients diagnosed with CRC, KRAS sequence variation was associated with increased mortality among patients with YO and LO tumors. In YO cancer, variant KRAS-associated mortality risk was higher in distal tumors than proximal tumors.

Characteristic Mutational Damages in Gastric and Colorectal Adenocarcinomas

INTRODUCTION

Gastric and colorectal adenocarcinomas are prevalent malignancies characterized by mutations in genes such as p53, RAS, and MDM2, which play crucial roles in tumorigenesis and cancer progression. Understanding the specific mutational patterns and their implications in these cancers was essential for identifying potential therapeutic targets.

AIM

To identify the nature of mutational disorders in the p53, p21Waf1, RAS and MDM2 genes, depending on the degree of cell differentiation by adenocarcinomas of the gastrointestinal tract.

METHODS

Genomic DNA was isolated from 200 samples of stomach tissue and 233 samples of colon and rectum adenocarcinomas. A total of 433 samples, including gastric adenocarcinomas, colon and rectum adenocarcinomas and adjacent tissues, were collected.

RESULTS

Genomic DNA was isolated, and mutational analysis of p53, RAS (HRAS, KRAS, NRAS), and MDM2 genes was performed using polymerase chain reaction, gel electrophoresis, and restriction enzyme analysis. The deletion of p53 exon-intron 5-6, as well as HRAS 12 and HRAS 61 mutations, were detected in 78% of poorly differentiated adenocarcinomas. The deletions of p53 exon-intron 7-9 - in 100% of moderately differentiated adenocarcinomas and 50-60% of adjacent tissues. The loss of WAF1 gene expression was registered in almost 90% of poorly differentiated adenocarcinomas and 20% of adjacent tissue samples. The KRAS and NRAS mutations in almost 63.9% of studied colon and rectal samples indicated autonomous cell growth. This explains the aggressive and metastatic growth of tumours and the ineffectiveness of growth factor inhibitors in colorectal cancer. Finding ways to influence specific substitutions in RAS genes could prevent and eliminate uncontrolled invasive tumour growth.

CONCLUSION

By identifying specific gene mutations and differences in genetic markers, the study provided insights for the development of targeted diagnostic methods and personalised treatment strategies, ultimately improving the clinical outcomes in the field of oncology.

Different prognostic values of KRAS exon 2 submutations and BRAF V600E mutation in microsatellite stable (MSS) and unstable (MSI) stage III colon cancer: an ACCENT/IDEA pooled analysis of seven trials

BACKGROUND

The prognostic value of KRAS and BRAFV600E mutations in stage III colon cancer (CC) remains controversial and has never been clearly analyzed in patients with microsatellite instability-high (MSI-H) tumors due to sample size limitations. Data are also lacking for KRAS submutations and prognosis.

PATIENTS AND METHODS

We examined clinicopathological variables and prognosis in patients with surgically resected stage III CC who participated in seven clinical trials from the ACCENT/IDEA databases. Associations between KRAS exon 2 and BRAFV600E mutations and time to recurrence (TTR), overall survival (OS), and survival after recurrence (SAR) were assessed using a Cox model. We also analyzed the prognostic value of KRAS exon 2 submutations.

RESULTS

Among 8460 patients, 11.4% had MSI-H status. In the MSI-H group, BRAFV600E, KRAS exon 2 mutants, and double-wild-type statuses were detected in 40.6%, 18.1%, and 41.3%, respectively, whereas and in the microsatellite stable (MSS) group, these were detected in 7.7%, 38.6%, and 53.8%, respectively. In the MSS group, 5-year TTR rates of 61.8%, 66.3%, and 72.9% were observed among patients with BRAFV600E, KRAS exon 2 mutants, and those who were DWT, respectively [adjusted hazard ratio (HR) = 1.58 and 1.31, both P < 0.001]. In the MSI-H group, 5-year TTR rates did not differ significantly among the mutated subgroups. Similar results were found for OS. However, survival after relapse was significantly shorter in the KRAS exon 2- and BRAFV600E-mutated patients in both MSS (adjusted HR = 2.06 and 1.15; both P < 0.05) and MSI-H (adjusted HR = 1.99 and 1.81; both P < 0.05) groups. In the MSS group, KRAS exon 2 mutations were associated with TTR, but only p.G12C, p.G12D, and p.G13D were associated with poor outcomes after disease recurrence.

CONCLUSIONS

Testing for both KRAS and BRAFV600E mutations in stage III patients should be considered as they can better define individual patient prognosis, and may also enable patient selection for (neo)adjuvant trials dedicated to specific molecular subtypes with poor prognosis.

Unraveling the Role of Molecular Profiling in Predicting Treatment Response in Stage III Colorectal Cancer Patients: Insights from the IDEA International Study

BACKGROUND

This study aimed to investigate the molecular profiles of 237 stage III CRC patients from the international IDEA study. It also sought to correlate these profiles with Toll-like and vitamin D receptor polymorphisms, clinicopathological and epidemiological characteristics, and patient outcomes.

METHODS

Whole Exome Sequencing and PCR-RFLP on surgical specimens and blood samples, respectively, were performed to identify molecular profiling and the presence of Toll-like and vitamin D polymorphisms. Bioinformatic analysis revealed mutational status.

RESULTS

Among the enrolled patients, 63.7% were male, 66.7% had left-sided tumors, and 55.7% received CAPOX as adjuvant chemotherapy. Whole exome sequencing identified 59 mutated genes in 11 different signaling pathways from the Kyoto Encyclopedia of Genes and Genomes (KEGG) CRC panel. On average, patients had 8 mutated genes (range, 2-21 genes). Mutations in ARAF and MAPK10 emerged as independent prognostic factors for reduced DFS (p = 0.027 and p < 0.001, respectively), while RAC3 and RHOA genes emerged as independent prognostic factors for reduced OS (p = 0.029 and p = 0.006, respectively). Right-sided tumors were also identified as independent prognostic factors for reduced DFS (p = 0.019) and OS (p = 0.043). Additionally, patients with tumors in the transverse colon had mutations in genes related to apoptosis, PIK3-Akt, Wnt, and MAPK signaling pathways.

CONCLUSIONS

Molecular characterization of tumor cells can enhance our understanding of the disease course. Mutations may serve as promising prognostic biomarkers, offering improved treatment options. Confirming these findings will require larger patient cohorts and international collaborations to establish correlations between molecular profiling, clinicopathological and epidemiological characteristics and clinical outcomes.

Different oncological features of colorectal cancer codon-specific KRAS mutations: Not codon 13 but codon 12 have prognostic value

BACKGROUND

Approximately 40% of colorectal cancer (CRC) cases are linked to Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations. KRAS mutations are associated with poor CRC prognosis, especially KRAS codon 12 mutation, which is associated with metastasis and poorer survival. However, the clinicopathological characteristics and prognosis of KRAS codon 13 mutation in CRC remain unclear.

AIM

To evaluate the clinicopathological characteristics and prognostic value of codon-specific KRAS mutations, especially in codon 13.

METHODS

This retrospective, single-center, observational cohort study included patients who underwent surgery for stage I-III CRC between January 2009 and December 2019. Patients with KRAS mutation status confirmed by molecular pathology reports were included. The relationships between clinicopathological characteristics and individual codon-specific KRAS mutations were analyzed. Survival data were analyzed to identify codon-specific KRAS mutations as recurrence-related factors using the Cox proportional hazards regression model.

RESULTS

Among the 2203 patients, the incidence of KRAS codons 12, 13, and 61 mutations was 27.7%, 9.1%, and 1.3%, respectively. Both KARS codons 12 and 13 mutations showed a tendency to be associated with clinical characteristics, but only codon 12 was associated with pathological features, such as stage of primary tumor (T stage), lymph node involvement (N stage), vascular invasion, perineural invasion, tumor size, and microsatellite instability. KRAS codon 13 mutation showed no associations (77.2% vs 85.3%, P = 0.159), whereas codon 12 was associated with a lower 5-year recurrence-free survival rate (78.9% vs 75.5%, P = 0.025). In multivariable analysis, along with T and N stages and vascular and perineural invasion, only codon 12 (hazard ratio: 1.399; 95% confidence interval: 1.034-1.894; P = 0.030) among KRAS mutations was an independent risk factor for recurrence.

CONCLUSION

This study provides evidence that KRAS codon 13 mutation is less likely to serve as a prognostic biomarker than codon 12 mutation for CRC in a large-scale cohort.

Oleic acid-induced metastasis of KRAS/p53-mutant colorectal cancer relies on concurrent KRAS activation and IL-8 expression bypassing EGFR activation

Background: Multigene mutations in colorectal cancer (CRC), including KRAS, BRAF, and p53, afford high metastatic ability and resistance to EGFR-targeting therapy. Understanding the molecular mechanisms regulating anti-EGFR-resistant CRC metastasis can improve CRC therapy. This study aimed to investigate the effects of IL-8 and the activation of KRAS on reactive oxygen species (ROS) production and metastasis of hyperlipidemia-associated CRC harboring mutations of KRAS and p53. Methods: The cytokine array analysis determined the up-expression of secreted factors, including IL-8. The clinical relevance of the relationship between IL-8 and angiopoietin-like 4 (ANGPTL4) was examined in CRC patients from National Cheng Kung University Hospital and TCGA dataset. Expressions of IL-8, ANGPTL4, NADPH oxidase 4 (NOX4), and epithelial-mesenchymal transition (EMT) markers in free fatty acids (FFAs)-treated KRAS/p53 mutant CRC cells were determined. The hyperlipidemia-triggered metastatic ability of CRC cells under treatments of antioxidants, statin, and cetuximab or knockdown of IL-8, KRAS, and EGFR was evaluated in vitro and in vivo. In addition, the effects of antioxidants and depletion of IL-8 and KRAS on the correlation between ROS production and hyperlipidemia-promoted CRC metastasis were also clarified. Results: In this study, we found that free fatty acids promoted KRAS/p53-mutant but not single-mutant or non-mutant CRC cell metastasis. IL-8, the most abundant secreted factor in KRAS/p53-mutant cells, was correlated with the upregulation of NOX4 expression and ROS production under oleic acid (OA)-treated conditions. In addition, the metastasis of KRAS/p53-mutant CRC relies on the ANGPTL4/IL-8/NOX4 axis and the activation of KRAS. The antioxidants and inactivation of KRAS also inhibited OA-induced EMT and metastasis. Although KRAS mediated EGF- and OA-promoted CRC cell invasion, the inhibition of EGFR did not affect OA-induced ANGPTL4/IL-8/NOX4 axis and CRC metastasis. The high-fat diet mice fed with vitamin E and statin or in IL-8-depleted cells significantly inhibited tumor extravasation and metastatic lung growth of CRC. Conclusion: The antioxidants, statins, and targeting IL-8 may provide better outcomes for treating metastatic CRC that harbors multigene mutations and anti-EGFR resistance.

Clinical, Pathological and Molecular Insights on KRAS, NRAS, BRAF, PIK3CA and TP53 Mutations in Metastatic Colorectal Cancer Patients from Northeastern Romania

Mutations in RAS, BRAF, PIK3CA, and TP53 are well-established genetic abnormalities in metastatic colorectal cancer (mCRC). However, limited information is available for patients from Eastern Europe, including Romania. In this retrospective analysis, we investigated 104 mCRC patients from the Northeastern region of Romania to determine the frequency, distribution, coexistence, and clinicopathological and molecular correlations of these mutations. TP53 was the most frequently mutated gene (73.1%), followed by KRAS (45.2%) and PIK3CA (6.7%). Patients with KRAS mutant tumors and wild-type TP53 genotype were found to have no personal history of gastrointestinal cancer (p = 0.02, p = 0.007). KRAS mutations in exon 3 were associated with the female gender (p = 0.02) and the absence of lymph node invasion (p = 0.02). PIK3CA mutations were linked to the absence of lymph node invasion (p = 0.006). TP53 mutations were associated with KRAS mutations in exon 2 (p = 0.006), ulcerated histopathologic type (p = 0.04), and G2 differentiation (p = 0.01). It provides novel insights into genetic variations specific to the population from Northeastern Romania, which has been underrepresented in previous studies within Eastern Europe. Furthermore, our findings enable the development of genetic profiles in a developing country with limited access to specialized genetic tests and facilitate comparisons with other populations.

Microsatellite Instability: A Review of Molecular Epidemiology and Implications for Immune Checkpoint Inhibitor Therapy

Microsatellite instability (MSI) is one of the most important molecular characteristics of a tumor, which occurs among various tumor types. In this review article, we examine the molecular characteristics of MSI tumors, both sporadic and Lynch-associated. We also overview the risks of developing hereditary forms of cancer and potential mechanisms of tumor development in patients with Lynch syndrome. Additionally, we summarize the results of major clinical studies on the efficacy of immune checkpoint inhibitors for MSI tumors and discuss the predictive role of MSI in the context of chemotherapy and checkpoint inhibitors. Finally, we briefly discuss some of the underlying mechanisms causing therapy resistance in patients treated with immune checkpoint inhibitors.

KRAS Mutational Profiles among Colorectal Cancer Patients in the East Coast of Peninsular Malaysia

BACKGROUND

KRAS is a key driver gene in colorectal carcinogenesis. Despite this, there are still limited data on the mutational status of KRAS amongst colorectal cancer (CRC) patients in Malaysia. In the present study, we aimed to analyze the KRAS mutational profiles on codons 12 and 13 amongst CRC patients in Hospital Universiti Sains Malaysia, Kelantan, located on the East Coast of Peninsular Malaysia.

METHODS

DNA were extracted from formalin-fixed, paraffin-embedded tissues obtained from 33 CRC patients diagnosed between 2018 and 2019. Amplifications of codons 12 and 13 of KRAS were conducted using conventional polymerase chain reaction (PCR) followed by Sanger sequencing.

RESULTS

Mutations were identified in 36.4% (12/33) of patients, with G12D (50%) being the most frequent single-point mutation observed, followed by G12V (25%), G13D (16.7%), and G12S (8.3%). No correlation was found between mutant KRAS and location of the tumor, staging, and initial carcinoembryonic antigen (CEA) level.

CONCLUSION

Current analyses revealed that a significant proportion of CRC patients in the East Coast of Peninsular Malaysia have KRAS mutations, where this frequency is higher compared to those in the West Coast. The findings of this study would serve as a precursor for further research that explores KRAS mutational status and the profiling of other candidate genes among Malaysian CRC patients.

PAK and PI3K pathway activation confers resistance to KRASG12C inhibitor sotorasib

BACKGROUND

KRAS is a frequently mutated oncogene in human cancer. Clinical studies on the covalent inhibitors of the KRASG12C mutant have reported promising results. However, primary and acquired resistance may limit their clinical use.

METHODS

Sotorasib-resistant cell lines were established. We explored the signalling pathways activated in these resistant cell lines and their roles in sotorasib resistance.

RESULTS

The resistant cells exhibited increased cell-matrix adhesion with increased levels of stress fibres and focal adherens. p21-activated kinases (PAKs) were activated in resistant cells, which phosphorylate MEK at serine 298 of MEK and serine 338 of c-Raf to activate the mitogen-activated protein kinase pathway. The PAK inhibitors FRAX597 and FRAX486 in synergy with sotorasib reduced the viability of KRASG12C mutant cancer cells. Furthermore, the PI3K/AKT pathway was constitutively active in sotorasib-resistant cells. The overexpression of constitutively activated PI3K or the knockdown of PTEN resulted in resistance to sotorasib. PI3K inhibitor alpelisib was synergistic with sotorasib in compromising the viability of KRASG12C mutant cancer cells. Moreover, PI3K and PAK pathways formed a mutual positive regulatory loop that mediated sotorasib resistance.

CONCLUSIONS

Our results indicate that the cell-matrix interaction-dependent activation of PAK mediates resistance to sotorasib through the activation of MAPK and PI3K pathways.

Mutations matter: An observational study of the prognostic and predictive value of KRAS mutations in metastatic colorectal cancer

BACKGROUND

About half of metastatic colorectal cancers (CRCs) harbor Rat Sarcoma (RAS) activating mutations as oncogenic driver, but the prognostic role of RAS mutations is not fully elucidated. Interestingly, specific hotspot mutations have been identified as potential candidates for novel targeted therapies in several malignancies as per G12C. This study aims at evaluating the association between KRAS hotspot mutations and patient characteristics, prognosis and response to antiangiogenic drugs.

METHODS

Data from RAS-mutated CRC patients referred to Careggi University Hospital, between January 2017 and April 2022 were retrospectively and prospectively collected. Tumor samples were assessed for RAS mutation status using MALDI-TOF Mass Spectrometry, Myriapod NGS-56G Onco Panel, or Myriapod NGS Cancer Panel DNA.

RESULTS

Among 1047 patients with available RAS mutational status, 183 KRAS-mutated patients with advanced CRC had adequate data for clinicopathological and survival analysis. KRAS mutations occurred at codon 12 in 67.2% of cases, codon 13 in 23.5%, codon 61 in 2.2%, and other codons in 8.2%. G12C mutation was identified in 7.1% of patients and exon 4 mutations in 7.1%. KRAS G12D mutation, as compared to other mutations, was significantly associated with liver metastases (1-sided p=0.005) and male sex (1-sided p=0.039), KRAS G12C mutation with peritoneal metastases (1-sided p=0.035), KRAS G12V mutation with female sex (1-sided p=0.025) and no surgery for primary tumor (1-sided p=0.005). No associations were observed between specific KRAS variants and age, ECOG PS, site of primary tumor, pattern of recurrence for resected patients, and lung, distant lymph node, bone, or brain metastases.Overall survival (OS) was significantly longer in patients with KRAS exon 4 mutations than in those with other KRAS mutations (mOS 43.6 months vs 20.6 months; HR 0.45 [0.21-0.99], p=0.04). No difference in survival was observed for mutations at codon 12/13/61 (p=0.1). Treatment with bevacizumab (BV) increased significatively mPFS (p=0.036) and mOS (p=0.019) of the entire population with a substantial benefit in mOS for G12V mutation (p=0.031).

CONCLUSIONS

Patterns of presentation and prognosis among patients with specific RAS hotspot mutations deserve to be extensively studied in large datasets, with a specific attention to the uncommon isoforms and the role of anti-angiogenic drugs.

Genomic profiling in low grade serous ovarian cancer: Identification of novel markers for disease diagnosis and therapy

OBJECTIVES

Low grade serous ovarian cancer (LGSOC) differs from high grade serous in terms of pathogenesis, molecular, genetic, and clinical features. Molecular studies have been hampered by small sample sizes, heterogenous histology, and lack of comprehensive testing. We sought to molecularly profile LGSOC in a homogenously tested, histologically confirmed cohort.

METHODS

Using hot-spot and whole exome next generation sequencing (NGS), fusion gene analysis interrogating RNA, fragment analysis, in situ hybridization and/or immunohistochemistry, 179 specimens were evaluated by Caris Life Sciences (Phoenix, AZ). A second independent histologic review confirmed histology in 153 specimens.

RESULTS

Most frequently mutated genes (5% or greater) were members of the mitogen-activated protein kinase (MAPK) pathway: KRAS (23.7%, n = 36), NRAS (11.2%, n = 19), NF1 (7.9%, n = 5), and BRAF (6.6%, n = 10). Class III mutations were seen in 3 of 10 BRAF mutations while 7 were Class I V600E. Overall, estrogen and progesterone receptor expression was 80.2% (n = 130) and 27.8% (n = 45), respectively. Of those that were hormone negative, nearly 50% contained KRAS or NF1 mutations. None were NRAS mutated. Markers of response to immunotherapy were low to absent.

CONCLUSION

BRAF mutations were seen to be lower than those traditionally reported. With increased MAPK activation resulting in ligand independent activation of ERα, a role of combination therapy with hormonal and targeted therapy should be considered as 49.2% of hormone negative specimens were KRAS or NF1 mutated. Absence of immunotherapy biomarkers suggest limited benefit to immunotherapeutic agents.

KRAS is a prognostic biomarker associated with diagnosis and treatment in multiple cancers

KRAS encodes K-Ras proteins, which take part in the MAPK pathway. The expression level of KRAS is high in tumor patients. Our study compared KRAS expression levels between 33 kinds of tumor tissues. Additionally, we studied the association of KRAS expression levels with diagnostic and prognostic values, clinicopathological features, and tumor immunity. We established 22 immune-infiltrating cell expression datasets to calculate immune and stromal scores to evaluate the tumor microenvironment. KRAS genes, immune check-point genes and interacting genes were selected to construct the PPI network. We selected 79 immune checkpoint genes and interacting related genes to calculate the correlation. Based on the 33 tumor expression datasets, we conducted GSEA (genome set enrichment analysis) to show the KRAS and other co-expressed genes associated with cancers. KRAS may be a reliable prognostic biomarker in the diagnosis of cancer patients and has the potential to be included in cancer-targeted drugs.

Development of a Nanostructured Electrochemical Genosensor for the Detection of the K-ras Gene

In the scientific literature, it has been documented that electrochemical genosensors are novel analytical tools with proven clinical diagnostic potential for the identification of carcinogenic processes due to genetic and epigenetic alterations, as well as infectious diseases due to viruses or bacteria. In the present work, we describe the construction of an electrochemical genosensor for the identification of the k12p.1 mutation; it was based on use of Screen-Printed Gold Electrode (SPGE), Cyclic Voltammetry (CV), and Atomic Force Microscopy (AFM), for the monitoring the electron transfer trough the functionalized nanostructured surface and corresponding morphological changes. The sensitivity of the genosensor showed a linear response for the identification of the k12p.1 mutation of the K-ras gene in the concentration range of 10 fM to 1 μM with a detection limit of 7.96 fM in the presence of doxorubicin (Dox) as DNA intercalating agent and indicator of the hybridization reaction. Thus, the electrochemical genosensor developed could be useful for the identification of diseases related with the K-ras oncogene.

Effect of TP53 deficiency and KRAS signaling on the bioenergetics of colon cancer cells in response to different substrates: A single cell study

Metabolic reprogramming is a hallmark of cancer. Somatic mutations in genes involved in oncogenic signaling pathways, including KRAS and TP53, rewire the metabolic machinery in cancer cells. We here set out to determine, at the single cell level, metabolic signatures in human colon cancer cells engineered to express combinations of activating KRAS gene mutations and TP53 gene deletions. Specifically, we explored how somatic mutations in these genes and substrate availability (lactate, glucose, substrate deprivation) from the extracellular microenvironment affect bioenergetic parameters, including cellular ATP, NADH and mitochondrial membrane potential dynamics. Employing cytosolic and mitochondrial FRET-based ATP probes, fluorescent NADH sensors, and the membrane-permeant cationic fluorescent probe TMRM in HCT-116 cells as a model system, we observed that TP53 deletion and KRAS mutations drive a shift in metabolic signatures enabling lactate to become an efficient metabolite to replenish both ATP and NADH following nutrient deprivation. Intriguingly, cytosolic, mitochondrial and overall cellular ATP measurements revealed that, in WT KRAS cells, TP53 deficiency leads to an enhanced ATP production in the presence of extracellular lactate and glucose, and to the greatest increase in ATP following a starvation period. On the other hand, oncogenic KRAS in TP53-deficient cells reversed the alterations in cellular ATP levels. Moreover, cell population measurements of mitochondrial and glycolytic metabolism using a Seahorse analyzer demonstrated that WT KRAS TP53-silenced cells display an increase of the basal respiration and tightly-coupled mitochondria, in the presence of glucose as substrate, compared to TP53 competent cells. Furthermore, cells possessing oncogenic KRAS, independently of TP53 status, showed less pronounced mitochondrial membrane potential changes in response to metabolic nutrients. Furthermore, analysis of cytosolic and mitochondrial NADH levels revealed that the simultaneous presence of TP53 deletion and oncogenic KRAS showed the most pronounced alteration in cytosolic and mitochondrial NADH during metabolic stress. In conclusion, our findings demonstrate how activating KRAS mutation and loss of TP53 remodel cancer metabolism and lead to alterations in bioenergetics under metabolic stress conditions by modulating cellular ATP production, NADH oxidation, mitochondrial respiration and function.

Colorectal cancers with a residual adenoma component: Clinicopathologic features and KRAS mutation

Background/Aim

Colorectal cancer is well known for its “adenoma-carcinoma” sequential carcinogenesis. Some colorectal cancers demonstrate a residual adenoma component during progression from adenoma to invasive carcinoma. However, the clinicopathological significance of residual adenoma component remains unclear. In this study, we aimed to investigate the clinicopathologic and molecular characteristics including the KRAS mutation in colorectal cancers containing a residual adenoma component.

Materials and methods

In this study, 498 surgically resected colorectal cancer patients were enrolled. Their detailed clinicopathologic features and results of molecular study including KRAS mutation test and microsatellite instability were analyzed.

Results

A residual adenoma component was identified in 42 (8.4%) patients with colorectal cancer. The presence of a residual adenoma component was associated with a high frequency of the KRAS mutation (65%, p = 0.031) as well as indolent clinicopathological features, including polypoid gross type (p < 0.001), well-differentiated histology (p < 0.001), low pT (p < 0.001) and pN stage (p = 0.003), absence of vascular invasion (p = 0.005), and a better progression-free prognosis (p = 0.029). The cases with an adenoma component had a 35.7% discordance rate on the KRAS mutation tests in their adenoma and carcinoma regions.

Conclusion

In conclusion, colorectal cancer with a residual adenoma component showed indolent clinicopathologic features and frequent KRAS mutations. Due to the discordance in the incidence of the KRAS mutation between the adenoma and carcinoma components, the adenoma component should be documented in the pathology report, and care should be taken not to include the adenoma component when collecting samples for molecular testing.

Impact of anatomical liver resection on patient survival in KRAS-wild-type colorectal liver metastasis: A multicenter retrospective study

BACKGROUND

Liver resection is a standard therapy for colorectal liver metastasis. However, the impact of anatomical resection and nonanatomical resection on the survival in patients with Kirsten rat sarcoma-wild-type and Kirsten rat sarcoma-mutated colorectal liver metastasis remain unclear. We investigated whether anatomical resection versus nonanatomical resection improves survival in colorectal liver metastasis stratified by Kirsten rat sarcoma mutational status.

METHODS

Among 639 consecutive patients with colorectal liver metastasis who underwent primary liver resection between January 2008 and December 2017, 349 patients were excluded due to their unknown Kirsten rat sarcoma mutational status, or due to receiving anatomical resection with concomitant non-anatomical resection, radiofrequency, or R2 resection. Accordingly, 290 patients with colorectal liver metastasis were retrospectively assessed. The relationships between resection types and survival were investigated in Kirsten rat sarcoma-wild-type and -mutated groups.

RESULTS

Anatomical resection was performed in 77/186 (41%) and 44/104 (42%) patients with Kirsten rat sarcoma-wild-type and Kirsten rat sarcoma-mutated genetic statuses, respectively. For both, the clinical-pathologic factors were comparable, except a larger maximum tumor size and surgical margin were observed in anatomical resection cases. Anatomical resection patients had significantly longer recurrence-free survival and overall survival than nonanatomical resection cases in the Kirsten rat sarcoma-wild-type group (recurrence-free survival, P < .001; overall survival, P = .005). No significant recurrence-free survival or overall survival differences were observed between Kirsten rat sarcoma-mutated anatomical resection and non-anatomical resection (recurrence-free survival, P = .132; overall survival, P = .563). Although, intrahepatic recurrence in Kirsten rat sarcoma-wild-type and -mutated colorectal liver metastasis was comparable (P = .973), extrahepatic recurrence was increased in Kirsten rat sarcoma-mutated versus -wild-type colorectal liver metastasis (P < .001).

CONCLUSION

In contrast to Kirsten rat sarcoma-mutated colorectal liver metastasis with higher extrahepatic recurrence after liver resection, local liver control via anatomical resection improved the postoperative survival in patients with Kirsten rat sarcoma-wild-type colorectal liver metastasis.

Prognostic and predictive molecular biomarkers in advanced colorectal cancer

The revolution of precision medicine has produced unprecedented seismic shifts in the treatment paradigm of advanced cancers. Among the major killers, colorectal cancer (CRC) is far behind the others. In fact, the great successes obtained in breast, NSCLC, melanoma, and genitourinary tract tumors have been observed only in fewer than 5 % metastatic colorectal cancer (mCRC): those with the mismatch repair deficiency (dMMR), a well-known predictive factor for to the outstanding efficacy of checkpoint inhibitors (CPI). The treatment of the remaining vast majority mCRC patients is still based upon only two molecular determinants: the RAS and BRAF mutational status. New promising biomarkers include HER2, tumor mutational burden (TMB) for its possible implications on CPI efficacy, and the extremely rare NTRK fusions. The Consensus Molecular Subtypes classification (CMS) is a good example of the efforts to combine different molecular features of this disease, although its relevance in clinical practice is still under investigation. In this Review, we focus on all these prognostic and predictive biomarkers, analyzing data from the most important clinical trials of the last years. We also try to rank them according to their prognostic and predictive power.

Prognostic Value of KRAS Mutations in Colorectal Cancer Patients

Colorectal cancer (CRC) remains a major public health issue. The detection of parameters that affect CRC prognosis is of great significance. KRAS mutations, play a crucial role in tumorigenesis with a strong predictive value. KRAS-mutated stage-IV CRC patients gain no benefit of the anti-EGFR therapy. The KRAS G12C mutation subtype is under investigation for treatment regimens. The present study aimed to detect various RAS mutations in a cohort of 578 RAS-mutated CRC patients; 49% of them had de novo metastatic disease; 60% were male; 71.4% had left-sided tumors; and 94.6% had a good performance status. KRAS mutations were detected in 93.2% of patients, with KRAS G12D being the most common subtype (30.1%). KRAS mutations presented shorter progression-free (PFS) and overall survival (OS), compared with NRAS mutations, although not significantly (PFS: 13.8 vs. 18.5 months; p = 0.552; OS: 53.1 vs. 60.9 months; p = 0.249). KRAS G12D mutations presented better OS rates (p = 0.04). KRAS G12C mutation, even though not significantly, presented worse PFS and OS rates. KRAS exon 3 and 4 mutations presented different PFS and OS rates, although these were not significant. Concluding, KRAS G12D and G12C mutations lead to better and worst prognosis, respectively. Further studies are warranted to validate such findings and their possible therapeutic implication.

The Role of ICG in Robot-Assisted Liver Resections

Introduction: Robotic-assisted liver surgery (RALS) with its known limitations is gaining more importance. The fluorescent dye, indocyanine green (ICG), is a way to overcome some of these limitations. It accumulates in or around hepatic masses. The integrated near-infrared cameras help to visualize this accumulation. We aimed to compare the influence of ICG staining on the surgical and oncological outcomes in patients undergoing RALS. Material and Methods: Patients who underwent RALS between 2014 and 2021 at the Department of General Surgery at the University Hospital Schleswig-Holstein, Campus Kiel, were included. In 2019, ICG-supported RALS was introduced. Results: Fifty-four patients were included, with twenty-eight patients (50.9%) receiving preoperative ICG. Hepatocellular carcinoma (32.1%) was the main entity resected, followed by the metastasis of colorectal cancers (17%) and focal nodular hyperplasia (15.1%). ICG staining worked for different tumor entities, but diffuse staining was noted in patients with liver cirrhosis. However, ICG-supported RALS lasted shorter (142.7 ± 61.8 min vs. 246.4 ± 98.6 min, p < 0.001), tumors resected in the ICG cohort were significantly smaller (27.1 ± 25.0 mm vs. 47.6 ± 35.2 mm, p = 0.021) and more R0 resections were achieved by ICG-supported RALS (96.3% vs. 80.8%, p = 0.075). Conclusions: ICG-supported RALS achieve surgically and oncologically safe results, while overcoming the limitations of RALS.

2-Pyridin-4-yl-methylene-beta-boswellic Acid-A Potential Candidate for Targeting O6-Methylguanine-DNA Methyltransferase Epi-transcriptional Reprogramming in KRAS G13D-Microsatellite Stable, G12V-Microsatellite Instable Mutant Colon Cancer

PMBA (2-Pyridin-4-yl-methylene-beta-boswellic acid), screened from among the 21 novel series of semisynthetic analogues of β-boswellic acid, is being presented as a lead compound for integrative management of KRAS mutant colorectal cancer (CRC), upon testing and analysis for its anticancerous activity on a panel of NCI-60 cancer cell lines and in vivo models of the disease. PMBA (1.7-29 μM) exhibited potent proliferation inhibition on the cell lines and showed sensitivity in microsatellite instability and microsatellite stable (GSE39582 and GSE92921) subsets of KRAS gene (Kirsten rat sarcoma viral oncogene homolog)-mutated colon cell lines, as revealed via flow cytometry analysis. A considerable decrease in mitogen-activated protein kinase pathway downstream effectors was observed in the treated cell lines via the western blot and STRING (Search tool for the retrieval of interacting genes/proteins) analysis. PMBA was further found to target KRAS at its guanosine diphosphate site. Treatment of the cell lines with PMBA showed significant reduction in MGMT promoter methylation but restored MGMT (O⁶-methylguanine-DNA methyltransferase) messenger ribonucleic acid expression via significant demethylation of the hypermethylated CpG (Cytosine phosphate guanine) sites in the MGMT promoter. A significant decrease in dimethylated H3K9 (Dimethylation of lysine 9 on histone 3) levels in the MGMT promoter in DNA hypo- and hypermethylated HCT-116^G13D and SW-620^G12V cells was observed after treatment. In the MNU (N-methyl-N-nitrosourea)-induced CRC in vivo model, PMBA instillation restricted and repressed polyp formation, suppressed tumor proliferation marker Ki67 (Marker of proliferation), ablated KRAS-associated cytokine signaling, and decreased mortality. Clinical trial data for the parent molecule revealed its effectiveness against the disease, oral bioavailability, and system tolerance. Comprehensively, PMBA represents a new class of KRAS inhibitors having a therapeutic window in the scope of a drug candidate. The findings suggest that the PMBA analogue could inhibit the growth of human CRC in vivo through downregulation of cancer-associated biomarkers as well as reactivate expression of the MGMT gene associated with increased H3K9 acetylation and H3K4 methylation with facilitated transcriptional activation, which might be important in silencing of genes associated with upregulation in the activity of KRAS.

Can Natural Products be Used to Overcome the Limitations of Colorectal Cancer Immunotherapy?

Colorectal cancer (CRC) is a common cancer of the digestive system that endangers human health. Immunotherapy is widely used in the treatment of patients with cancer. Some patients with dMMR/MSI-H CRC benefit from treatments that use immune checkpoint inhibitors, but most CRC patients are not sensitive to immunotherapy. Furthermore, internal resistance and immune escape lead to a reduced immunotherapy response. Therefore, the development of an effective combination therapy to improve the response rate to immunotherapy is a goal of cancer research. Natural products are potential candidates for comprehensive cancer treatments due to their wide range of immunomodulatory effects through multifactorial underlying mechanisms. In this review, we summarize the challenges in the treatment of CRC and assess the immunomodulatory effects of natural products and their active components. Our work suggests that natural products represent potential options for combined CRC immunotherapy.

Diagnostic and Prognostic Values of KRAS Mutations on EUS-FNA Specimens and Circulating Tumor DNA in Patients With Pancreatic Cancer

INTRODUCTION

The ability of carbohydrate antigen 19-9 (CA19-9) to differentiate pancreatic cancer from other benign pancreatic lesions is unsatisfactory. This study explored the diagnostic value of KRAS gene mutations and plasma circulating tumor DNA (ctDNA) in patients with pancreatic cancer.

METHODS

The prospective cohort study comprised 149 consecutive patients with solid pancreatic lesions who underwent endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA). KRAS subtype mutations were analyzed by digital droplet PCR (ddPCR) in EUS-FNA histopathology tissue samples, and blood samples were sent for plasma ctDNA analysis. The final diagnosis was based on surgical resection pathology or follow-up for at least 2 years.

RESULTS

Adding KRAS mutation ddPCR increased the sensitivity and accuracy of EUS-FNA from 71.4% to 91.6% (P < 0.001) and 75.8% to 88.6% (P < 0.001), respectively. By comparison, the sensitivities of circulating biomarkers ctDNA and CA19-9 were only 35.2% and 71.2%. The area under the curve of the receiver operating characteristic curve (AUC) of EUS-FNA and KRAS ddPCR combination was >0.90 for distinguishing pancreatic cancer from benign lesions, whereas the AUC of EUS-FNA and CA19-9 combination was 0.83. The median survival time was significantly shorter in patients with G12D KRAS mutations than that in patients with other mutations (180 vs 240 days, P < 0.001).

DISCUSSION

FNA tissue sample KRAS mutation analysis in tissues significantly improves the diagnostic accuracy of cyto/histopathological evaluation in EUS-FNA samples. The combination of EUS-FNA and tissue sample KRAS ddPCR provided a more accurate method for pancreatic cancer diagnosis, superior to the combination of EUS-FNA and CA19-9/ctDNA. G12D KRAS mutations in pancreatic cancer were independently associated with poor overall survival.

The prognostic value of KRAS mutation in locally advanced rectal cancer

BACKGROUND

The prognostic value of the KRAS proto-oncogene mutation in colorectal cancer has been debated. Herein, we analyzed the National Cancer Database (NCDB) to assess the role of KRAS mutation as a prognostic marker in patients with locally advanced rectal cancer (LARC).

METHODS

We identified LARC patients treated with neoadjuvant chemoradiation from 2004-2015 excluding those with stage I/IV disease and unknown KRAS status. Multivariable logistic regression identified variables associated with KRAS positivity. Propensity adjusted univariable and multivariable analyses identified predictors of survival.

RESULTS

Of the 784 eligible patients, 506 were KRAS-negative (KRAS -) and 278 were KRAS-positive (KRAS +). Median survival was 63.6 months and 76.3 months for KRAS + and KRAS - patients respectively, with propensity adjusted 3 and 5-year survival of 79.9% vs. 83.6% and 56.7% vs. 61.9% respectively (HR 1.56, p 1.074-2.272). Male sex, no insurance, and KRAS + disease were associated with poorer survival on unadjusted and propensity adjusted multivariable analyses.

CONCLUSIONS

Our analysis of KRAS + LARC suggest that KRAS + disease is associated with poorer overall survival. Given the inherent limitations of retrospective data, prospective validation is warranted.

Synergistic enhanced rolling circle amplification based on mutS and radical polymerization for single-point mutation DNA detection

The detection of nucleic acids in biofluids is essential for changing the paradigm of disease diagnosis. As there are very few nucleic acids present in human biofluids, a high sensitivity method is required to detect nucleic acids for disease diagnosis. The Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation is associated with non-small cell lung cancer. It is a point mutation and requires a highly selective detection technique. In this study, high sensitivity and selectivity were achieved for the detection of KRAS mutation using rolling circle amplification (RCA), atomic transfer radical polymerization (ATRP), mutS enzyme, and electrochemical sensors. Although RCA can isothermally amplify DNA, it has low selectivity for detecting single-base mismatch DNA, and its sensitivity is not suitable for circulating tumor DNA detection. The selectivity of RCA was improved by using mutS, which can bind specifically to point mutations. In addition, as a method of isothermal radical polymerization, ATRP was used to amplify the weak signal of RCA. Since RCA and ATRP reactions occur simultaneously, detection time was reduced, and the calculated detection limit was 3.09 aM. Computational and experimental analyses were conducted to verify each detection step and the combination of mutS, ATRP, and RCA. The experiment was performed using normal human serum samples for biological application, and the proposed detection method was confirmed to have excellent potential for diagnosing cancer patients.

Integrated Analysis of Necroptosis-Related Genes for Prognosis, Immune Microenvironment Infiltration, and Drug Sensitivity in Colon Cancer

Background

Necroptosis, is intimately linked to tumor development and prognosis and has been considered as a target for anticancer therapy. However, the role of necroptosis-related genes (NRGs) in colon cancer is unclear.

Methods

In the present study, we screened 76 NRGs from previous studies and described the landscape of transcriptomic and genetic variation of NRGs in colon cancer (CC) patient samples. Molecular subtypes of necroptosis in colon cancer were identified by clustering analysis, and these molecular subtypes were linked to patient prognosis and TME cell infiltration characteristics. Then, the NRS-score for predicting overall survival (OS) was built based on the TCGA database and validated in the GSE39582 cohort for its predictive power in CC patients. Besides, the ESTIMATE and CIBERSORT algorithms were applied to explore the relationship between NRS-score and tumor immune microenvironment.

Results

We identified two molecular subtypes associated with necroptosis in CC, which have diverse prognosis and immune microenvironment characteristics. Based on the differentially expressed genes between the two molecular subtypes, we further developed a necroptosis risk score signature, referred to as NRS-score. High NRS-score was associated with poor prognosis in CC through immunosuppressive microenvironment and immune escape mechanisms. The nomogram based on NRS-score showed excellent ability to predict prognosis. In addition, NRS-score presented a positive correlation with tumor mutational burden (TMB) and immune checkpoint blockade (ICB) expression and was closely correlated with multiple anticancer agent susceptibility.

Conclusion

This work revealed a close relationship between necroptosis and the prognosis and immune microenvironment of colon cancer. The NRS-score based on the 8-gene signature may be used to predict the sensitivity of immunotherapy and chemotherapy in colon cancer patients, and provides a foundation for future studies targeting necroptosis and its immune microenvironment.

KRAS: A Druggable Target in Colon Cancer Patients

Mutations in KRAS are among the most frequent aberrations in cancer, including colon cancer. KRAS direct targeting is daunting due to KRAS protein resistance to small molecule inhibition. Moreover, its elevated affinity to cellular guanosine triphosphate (GTP) has made the design of specific drugs challenging. Indeed, KRAS was considered 'undruggable'. KRASG12C is the most commonly mutated variant of KRAS in non-small cell lung cancer. Currently, the achievements obtained with covalent inhibitors of this variant have given the possibility to assess the best therapeutic approach to KRAS-driven tumors. Mutation-related biochemical assets and the tissue of origin are expected to influence responses to treatment. Further attempts to obtain mutant-specific KRAS (KRASG12C) switch-II covalent inhibitors are ongoing and the results are promising. Drugs targeted to block KRAS effector pathways could be combined with direct KRAS inhibitors, immunotherapy or T cell-targeting approaches in KRAS-mutant tumors. The development of valuable combination regimens will be essential against potential mechanisms of resistance that may arise during treatment.

Downregulation of KRAB zinc finger proteins in 5-fluorouracil resistant colorectal cancer cells

Radio-chemotherapy with 5-flu orouracil (5-FU) is the standard of care treatment for patients with colorectal cancer, but it is only effective for a third of them. Despite our understanding of the mechanism of action of 5-FU, drug resistance remains a significant limitation to the clinical use of 5-FU, as both intrinsic and acquired chemoresistance represents the major obstacles for the success of 5-FU-based chemotherapy. In order to identify the mechanism of acquired resistance, 5-FU chemoresistance was induced in CRC cell lines by passaging cells with increasing concentrations of 5-FU. To study global molecular changes, quantitative proteomics and transcriptomics analyses were performed on these cell lines, comparing the resistant cells as well as the effect of chemo and radiotherapy. Interestingly, a very high proportion of downregulated genes were annotated as transcription factors coding for Krüppel-associated box (KRAB) domain-containing zinc-finger proteins (KZFPs), the largest family of transcriptional repressors. Among nearly 350 KRAB-ZFPs, almost a quarter were downregulated after the induction of a 5-FU-resistance including a common one between the three CRC cell lines, ZNF649, whose role is still unknown. To confirm the observations of the proteomic and transcriptomic approaches, the abundance of 20 different KZFPs and control mRNAs was validated by RT-qPCR. In fact, several KZFPs were no longer detectable using qPCR in cell lines resistant to 5-FU, and the KZFPs that were downregulated only in one or two cell lines showed similar pattern of expression as measured by the omics approaches. This proteomic, transcriptomic and genomic analysis of intrinsic and acquired resistance highlights a possible new mechanism involved in the cellular adaptation to 5-FU and therefore identifies potential new therapeutic targets to overcome this resistance.