Immune modulatory effects of oncogenic KRAS in cancer

Development and Validation of a Prognostic Gene Signature Correlated With M2 Macrophage Infiltration in Esophageal Squamous Cell Carcinoma

Background

Esophageal squamous cell carcinoma (ESCC) is the most common type of esophageal cancer and the seventh most prevalent cause of cancer-related death worldwide. Tumor microenvironment (TME) has been confirmed to play an crucial role in ESCC progression, prognosis, and the response to immunotherapy. There is a need for predictive biomarkers of TME-related processes to better prognosticate ESCC outcomes.

Aim

To identify a novel gene signature linked with the TME to predict the prognosis of ESCC.

Methods

We calculated the immune/stromal scores of 95 ESCC samples from The Cancer Genome Atlas (TCGA) using the ESTIMATE algorithm, and identified differentially expressed genes (DEGs) between high and low immune/stromal score patients. The key prognostic genes were further analyzed by the intersection of protein–protein interaction (PPI) networks and univariate Cox regression analysis. Finally, a risk score model was constructed using multivariate Cox regression analysis. We evaluated the associations between the risk score model and immune infiltration via the CIBERSORT algorithm. Moreover, we validated the signature using the Gene Expression Omnibus (GEO) database. Within the ten gene signature, five rarely reported genes were further validated with quantitative real time polymerase chain reaction (qRT-PCR) using an ESCC tissue cDNA microarray.

Results

A total of 133 up-regulated genes were identified as DEGs. Ten prognostic genes were selected based on intersection analysis of univariate COX regression analysis and PPI, and consisted of C1QA, C1QB, C1QC, CD86, C3AR1, CSF1R, ITGB2, LCP2, SPI1, and TYROBP (HR>1, p<0.05). The expression of 9 of these genes in the tumor samples were significantly higher compared to matched adjacent normal tissue based on the GEO database (p<0.05). Next, we assessed the ability of the ten-gene signature to predict the overall survival of ESCC patients, and found that the high-risk group had significantly poorer outcomes compared to the low-risk group using univariate and multivariate analyses in the TCGA and GEO cohorts (HR=2.104, 95% confidence interval:1.343-3.295, p=0.001; HR=1.6915, 95% confidence interval:1.053-2.717, p=0.0297). Additionally, receiver operating characteristic (ROC) curve analysis demonstrated a relatively sensitive and specific profile for the signature (1-, 2-, 3-year AUC=0.672, 0.854, 0.81). To identify the basis for these differences in the TME, we performed correlation analyses and found a significant positive correlation with M1 and M2 macrophages and CD8+ T cells, as well as a strong correlation to M2 macrophage surface markers. A nomogram based on the risk score and select clinicopathologic characteristics was constructed to predict overall survival of ESCC patients. For validation, qRT-PCR of an ESCC patient cDNA microarray was performed, and demonstrated that C1QA, C3AR1, LCP2, SPI1, and TYROBP were up-regulated in tumor samples and predict poor prognosis.

Conclusion

This study established and validated a novel 10-gene signature linked with M2 macrophages and poor prognosis in ESCC patients. Importantly, we identified C1QA, C3AR1, LCP2, SPI1, and TYROBP as novel M2 macrophage-correlated survival biomarkers. These findings may identify potential targets for therapy in ESCC patients.

Interleukin-1 signaling in solid organ malignancies

As inflammation plays a critical role in the development and progression of cancer, therapeutic targeting of cytokine pathways involved in both tumorigenesis and dictating response to clinical treatments are of significant interest. Recent evidence has highlighted the importance of the pro-inflammatory cytokine interleukin-1 (IL-1) as a key mediator of tumor growth, metastatic disease spread, immunosuppression, and drug resistance in cancer. IL-1 promotes tumorigenesis through diverse mechanisms, including the activation of oncogenic signaling pathways directly in tumor cells and via orchestrating crosstalk between the cellular constituents of the tumor microenvironment (TME), thereby driving cancer growth. This review will provide an overview of IL-1 signaling and physiology and summarize the disparate mechanisms involving IL-1 in tumorigenesis and cancer progression. Additionally, clinical studies targeting IL-1 signaling in the management of solid organ tumors will be summarized herein.

Barriers to Immunotherapy in Ovarian Cancer: Metabolic, Genomic, and Immune Perturbations in the Tumour Microenvironment

A lack of explicit early clinical signs and effective screening measures mean that ovarian cancer (OC) often presents as advanced, incurable disease. While conventional treatment combines maximal cytoreductive surgery and platinum-based chemotherapy, patients frequently develop chemoresistance and disease recurrence. The clinical application of immune checkpoint blockade (ICB) aims to restore anti-cancer T-cell function in the tumour microenvironment (TME). Disappointingly, even though tumour infiltrating lymphocytes are associated with superior survival in OC, ICB has offered limited therapeutic benefits. Herein, we discuss specific TME features that prevent ICB from reaching its full potential, focussing in particular on the challenges created by immune, genomic and metabolic alterations. We explore both recent and current therapeutic strategies aiming to overcome these hurdles, including the synergistic effect of combination treatments with immune-based strategies and review the status quo of current clinical trials aiming to maximise the success of immunotherapy in OC.

Targeting Oncogenic KRAS in Non-Small-Cell Lung Cancer

Simple Summary

v-Ki-ras2 Kirsten rat sarcoma viral oncogene (KRAS) is the most common driver in NSCLC, and targeting oncogenic KRAS is a major challenge in the treatment of non-small-cell lung cancer (NSCLC). While several covalent KRAS G12C inhibitors have emerged as a novel anti-KRAS therapy, the development of combined therapies involving the targeting of oncogenic KRAS plus other targeted drugs is still required given the vast heterogeneity of KRAS-mutated tumors. In this review, we summarize the biological and immunological characteristics of oncogenic KRAS-driven NSCLC and the preclinical and clinical evidence for mutant KRAS-targeted therapies. We also discuss the mechanisms of resistance to KRAS G12C inhibitors and possible therapeutic strategies to overcome this drug resistance.

Abstract

Recent advances in molecular biology and the resultant identification of driver oncogenes have achieved major progress in precision medicine for non-small-cell lung cancer (NSCLC). v-Ki-ras2 Kirsten rat sarcoma viral oncogene (KRAS) is the most common driver in NSCLC, and targeting KRAS is considerably important. The recent discovery of covalent KRAS G12C inhibitors offers hope for improving the prognosis of NSCLC patients, but the development of combination therapies corresponding to tumor characteristics is still required given the vast heterogeneity of KRAS-mutated NSCLC. In this review, we summarize the current understanding of KRAS mutations regarding the involvement of malignant transformation and describe the preclinical and clinical evidence for targeting KRAS-mutated NSCLC. We also discuss the mechanisms of resistance to KRAS G12C inhibitors and possible combination treatment strategies to overcome this drug resistance.

Resistance of B-Cell Lymphomas to CAR T-Cell Therapy Is Associated With Genomic Tumor Changes Which Can Result in Transdifferentiation

Despite the impressive efficacy of chimeric antigen receptor (CAR) T-cell therapy (CART) in B-cell non-Hodgkin lymphomas, durable responses are uncommon. The histopathologic and molecular features associated with treatment failure are still largely unknown. Therefore, we have analyzed 19 sequential tumor samples from 9 patients, prior anti-CD19 CART (pre-CART) and at relapse (post-CART), using immunohistochemistry, fluorescence in situ hybridization, array comparative genomic hybridization, next-generation DNA and RNA sequencing, and genome-scale DNA methylation. The initial diagnosis was diffuse large B-cell lymphoma (n=6), double-hit high-grade B-cell lymphoma (n=1), and Burkitt lymphoma (n=2). Histopathologic features were mostly retained at relapse in 7/9 patients, except the frequent loss of 1 or several B-cell markers. The remaining 2 cases (1 diffuse large B-cell lymphoma and 1 Burkitt lymphoma) displayed a dramatic phenotypic shift in post-CART tumors, with the drastic downfall of B-cell markers and emergence of T-cell or histiocytic markers, despite the persistence of identical clonal immunoglobulin gene rearrangements. The post-CART tumor with aberrant T-cell phenotype showed reduced mRNA expression of most B-cell genes with increased methylation of their promoter. Fluorescence in situ hybridization and comparative genomic hybridization showed global stability of chromosomal alterations in all paired samples, including 17p/TP53 deletions. New pathogenic variants acquired in post-CART samples included mutations triggering the PI3K pathway (PIK3R1, PIK3R2, PIK3C2G) or associated with tumor aggressiveness (KRAS, INPP4B, SF3B1, SYNE1, TBL1XR1). These results indicate that CART-resistant B-cell non-Hodgkin lymphomas display genetic remodeling, which may result in profound dysregulation of B-cell differentiation. Acquired mutations in the PI3K and KRAS pathways suggest that some targeted therapies could be useful to overcome CART resistance.

Construction and Validation of an Immune-Related Gene Prognostic Index for Esophageal Squamous Cell Carcinoma

Immune checkpoint inhibitor (ICI) therapy may benefit patients with advanced esophageal squamous cell carcinoma (ESCC); however, novel biomarkers are needed to help predict the response of patients to treatment. Differentially expressed immune-related genes within The Cancer Genome Atlas ESCC dataset were selected using the weighted gene coexpression network and lasso Cox regression analyses. Based on these data, an immune-related gene prognostic index (IRGPI) was constructed. The molecular characteristics of the different IRGPI subgroups were assessed using mutation information and gene set enrichment analysis. Differences in immune cell infiltration and the response to ICI therapy and other drugs were also analyzed. Additionally, tumor and adjacent control tissues were collected from six patients with ESCC and the expression of these genes was verified using real-time quantitative polymerase chain reaction. IRGPI was designed based on CLDN1, HCAR3, FNBP1L, and BRCA2, the expression of which was confirmed in ESCC samples. The prognosis of patients in the high-IRGPI group was poor, as verified using publicly available expression data. KMT2D mutations were more common in the high-IRGPI group. Enrichment analysis revealed an active immune response, and immune infiltration assessment showed that the high-IRGPI group had an increased infiltration degree of CD8 T cells, which contributed to the improved response to ICI treatment. Collectively, these data demonstrate that IRGPI is a robust biomarker for predicting the prognosis and response to therapy of patients with ESCC.

Analysis of KRAS Mutation Subtype in Tissue DNA and Cell-Free DNA Using Droplet Digital PCR and the Function of Cell-Free DNA as a Recurrence Predictive Marker in Pancreatic Cancer

KRAS mutation is a major regulator in the tumor progression of pancreatic cancer. Here, we compared the frequency and mutation burden of KRAS mutation subtypes with paired tumor tissue and blood in patients and examined their clinical significance. DNA from tumor tissues and cell-free DNA (cfDNA) from preoperative blood were obtained from 70 patients with pancreatic cancer. Subtypes and mutation burdens of KRAS G12D and G12V mutations were evaluated using droplet digital PCR. Comparing the presence of mutations in tissue, accumulative and simultaneous mutations of G12D or G12V were identified of 67 (95.7%), and 48 patients (68.6%). Conversely, in blood, they were only identified in 18 (25.7%) and four (5.7%) patients; respectively. Next, comparing the mutation burden in tissue, the mutation burden varied from less than 0.1 to more than five, whereas that of cfDNA in blood was mostly between one and five, as cases with a mutation burden lower than 0.1 and higher than five were rare. Finally, the presence of the G12V mutation alone in cfDNA and the combination of the G12V mutation with elevated CA 19-9 levels were associated with poor recurrence-free survival. These fundamental data on the KRAS mutation subtypes and their clinical significance could support their potential as predictive markers for postoperative recurrence.

Oncogenic KRAS-Induced Feedback Inflammatory Signaling in Pancreatic Cancer: An Overview and New Therapeutic Opportunities

Pancreatic ductal adenocarcinoma (PDAC) remains highly refractory to treatment. While the KRAS oncogene is present in almost all PDAC cases and accounts for many of the malignant feats of PDAC, targeting KRAS or its canonical, direct effector cascades remains unsuccessful in patients. The recalcitrant nature of PDAC is also heavily influenced by its highly fibro-inflammatory tumor microenvironment (TME), which comprises an acellular extracellular matrix and various types of non-neoplastic cells including fibroblasts, immune cells, and adipocytes, underscoring the critical need to delineate the bidirectional signaling interplay between PDAC cells and the TME in order to develop novel therapeutic strategies. The impact of tumor-cell KRAS signaling on various cell types in the TME has been well covered by several reviews. In this article, we critically reviewed evidence, including work from our group, on how the feedback inflammatory signals from the TME impact and synergize with oncogenic KRAS signaling in PDAC cells, ultimately augmenting their malignant behavior. We discussed past and ongoing clinical trials that target key inflammatory pathways in PDAC and highlight lessons to be learned from outcomes. Lastly, we provided our perspective on the future of developing therapeutic strategies for PDAC through understanding the breadth and complexity of KRAS and the inflammatory signaling network.

The RXR Agonist MSU42011 Is Effective for the Treatment of Preclinical HER2+ Breast Cancer and Kras-Driven Lung Cancer

(1) Background: Notwithstanding numerous therapeutic advances, 176,000 deaths from breast and lung cancers will occur in the United States in 2021 alone. The tumor microenvironment and its modulation by drugs have gained increasing attention and relevance, especially with the introduction of immunotherapy as a standard of care in clinical practice. Retinoid X receptors (RXRs) are members of the nuclear receptor superfamily and upon ligand binding, function as transcription factors to modulate multiple cell functions. Bexarotene, the only FDA-approved RXR agonist, is still used to treat cutaneous T-cell lymphoma. (2) Methods: To test the immunomodulatory and anti-tumor effects of MSU42011, a new RXR agonist, we used two different immunocompetent murine models (MMTV-Neu mice, a HER2 positive model of breast cancer and the A/J mouse model, in which vinyl carbamate is used to initiate lung tumorigenesis) and an immunodeficient xenograft lung cancer model. (3) Results: Treatment of established tumors in immunocompetent models of HER2-positive breast cancer and Kras-driven lung cancer with MSU42011 significantly decreased the tumor burden and increased the ratio of CD8/CD4, CD25 T cells, which correlates with enhanced anti-tumor efficacy. Moreover, the combination of MSU42011 and immunotherapy (anti-PDL1 and anti-PD1 antibodies) significantly (p < 0.05) reduced tumor size vs. individual treatments. However, MSU42011 was ineffective in an athymic human A549 lung cancer xenograft model, supporting an immunomodulatory mechanism of action. (4) Conclusions: Collectively, these data suggest that the RXR agonist MSU42011 can be used to modulate the tumor microenvironment in breast and lung cancer.

Ras-p53 genomic cooperativity as a model to investigate mechanisms of innate immune regulation in gastrointestinal cancers

Despite increasingly thorough mechanistic understanding of the dominant genetic drivers of gastrointestinal (GI) tumorigenesis (e.g., Ras/Raf, TP53, etc.), only a small proportion of these molecular alterations are therapeutically actionable. In an attempt to address this therapeutic impasse, our group has proposed an innovative extreme outlier model to identify novel cooperative molecular vulnerabilities in high-risk GI cancers which dictate prognosis, correlate with distinct patterns of metastasis, and define therapeutic sensitivity or resistance. Our model also proposes comprehensive investigation of their downstream transcriptomic, immunomic, metabolic, or upstream epigenomic cellular consequences to reveal novel therapeutic targets in previously “undruggable” tumors with high-risk genomic features. Leveraging this methodology, our and others’ data reveal that the genomic cooperativity between Ras and p53 alterations is not only prognostically relevant in GI malignancy, but may also represent the incipient molecular events that initiate and sustain innate immunoregulatory signaling networks within the GI tumor microenvironment, driving T-cell exclusion and therapeutic resistance in these cancers. As such, deciphering the unique transcriptional programs encoded by Ras-p53 cooperativity that promote innate immune trafficking and chronic inflammatory tumor-stromal-immune crosstalk may uncover immunologic vulnerabilities that could be exploited to develop novel therapeutic strategies for these difficult-to-treat malignancies.

Highlights on the Role of KRAS Mutations in Reshaping the Microenvironment of Pancreatic Adenocarcinoma

The most frequent mutated oncogene family in the history of human cancer is the RAS gene family, including NRAS, HRAS, and, most importantly, KRAS. A hallmark of pancreatic cancer, recalcitrant cancer with a very low survival rate, is the prevalence of oncogenic mutations in the KRAS gene. Due to this fact, studying the function of KRAS and the impact of its mutations on the tumor microenvironment (TME) is a priority for understanding pancreatic cancer progression and designing novel therapeutic strategies for the treatment of the dismal disease. Despite some recent enlightening studies, there is still a wide gap in our knowledge regarding the impact of KRAS mutations on different components of the pancreatic TME. In this review, we will present an updated summary of mutant KRAS role in the initiation, progression, and modulation of the TME of pancreatic ductal adenocarcinoma (PDAC). This review will highlight the intriguing link between diabetes mellitus and PDAC, as well as vitamin D as an adjuvant effective therapy via TME modulation of PDAC. We will also discuss different ongoing clinical trials that use KRAS oncogene signaling network as therapeutic targets.

Determinants of Homologous Recombination Deficiency in Pancreatic Cancer

Pancreatic cancer is a treatment-resistant malignancy associated with high mortality. However, defective homologous recombination (HR), a DNA repair mechanism required for high-fidelity repair of double-strand DNA breaks, is a therapeutic vulnerability. Consistent with this, a subset of patients with pancreatic cancer show unique tumor responsiveness to HR-dependent DNA damage triggered by certain treatments (platinum chemotherapy and PARP inhibitors). While pathogenic mutations in HR genes are a major driver of this sensitivity, another layer of diverse tumor intrinsic and extrinsic factors regulate the HR deficiency (HRD) phenotype. Defining the mechanisms that drive HRD may guide the development of novel strategies and therapeutics to induce treatment sensitivity in non-HRD tumors. Here, we discuss the complexity underlying HRD in pancreatic cancer and highlight implications for identifying and treating this distinct subset of patients.

Modulating Tumor Microenvironment: A Review on STK11 Immune Properties and Predictive vs Prognostic Role for Non-small-cell Lung Cancer Immunotherapy

OPINION STATEMENT

The quest for immunotherapy (IT) biomarkers is an element of highest clinical interest in both solid and hematologic tumors. In non-small-cell lung cancer (NSCLC) patients, besides PD-L1 expression evaluation with its intrinsic limitations, tissue and circulating parameters, likely portraying the tumor and its stromal/immune counterparts, have been proposed as potential predictors of IT responsiveness. STK11 mutations have been globally labeled as markers of IT resistance. After a thorough literature review, STK11 mutations condition the prognosis of NSCLC patients receiving ICI-containing regimens, implying a relevant biological and clinical significance. On the other hand, waiting for prospective and solid data, the putative negative predictive value of STK11 inactivation towards IT is sustained by less evidence. The physiologic regulation of multiple cellular pathways performed by STK11 likely explains the multifaceted modifications in tumor cells, stroma, and tumor immune microenvironment (TIME) observed in STK11 mutant lung cancer, particularly explored in the molecular subgroup of KRAS co-mutation. IT approaches available thus far in NSCLC, mainly represented by anti-PD-1/PD-L1 inhibitors, are not promising in the case of STK11 inactivation. Perceptive strategies aimed at modulating the TIME, regardless of STK11 status or specifically addressed to STK11-mutated cases, will hopefully provide valid therapeutic options to be adopted in the clinical practice.

Carbon Dioxide-Derived Biodegradable and Cationic Polycarbonates as a New siRNA Carrier for Gene Therapy in Pancreatic Cancer

Pancreatic cancer is an aggressive malignancy associated with poor prognosis and a high tendency in developing infiltration and metastasis. K-ras mutation is a major genetic disorder in pancreatic cancer patient. RNAi-based therapies can be employed for combating pancreatic cancer by silencing K-ras gene expression. However, the clinical application of RNAi technology is appreciably limited by the lack of a proper siRNA delivery system. To tackle this hurdle, cationic poly (cyclohexene carbonate) s (CPCHCs) using widely sourced CO₂ as the monomer are subtly synthesized via ring-opening copolymerization (ROCOP) and thiol-ene functionalization. The developed CPCHCs could effectively encapsulate therapeutic siRNA to form CPCHC/siRNA nanoplexes (NPs). Serving as a siRNA carrier, CPCHC possesses biodegradability, negligible cytotoxicity, and high transfection efficiency. In vitro study shows that CPCHCs are capable of effectively protecting siRNA from being degraded by RNase and promoting a sustained endosomal escape of siRNA. After treatment with CPCHC/siRNA NPs, the K-ras gene expression in both pancreatic cancer cell line (PANC-1 and MiaPaCa-2) are significantly down-regulated. Subsequently, the cell growth and migration are considerably inhibited, and the treated cells are induced into cell apoptotic program. These results demonstrate the promising potential of CPCHC-mediated siRNA therapies in pancreatic cancer treatment.

Targeting KRAS in pancreatic cancer: new drugs on the horizon

Kirsten Rat Sarcoma (KRAS) is a master oncogene involved in cellular proliferation and survival and is the most commonly mutated oncogene in all cancers. Activating KRAS mutations are present in over 90% of pancreatic ductal adenocarcinoma (PDAC) cases and are implicated in tumor initiation and progression. Although KRAS is a critical oncogene, and therefore an important therapeutic target, its therapeutic inhibition has been very challenging, and only recently specific mutant KRAS inhibitors have been discovered. In this review, we discuss the activation of KRAS signaling and the role of mutant KRAS in PDAC development. KRAS has long been considered undruggable, and many drug discovery efforts which focused on indirect targeting have been unsuccessful. We discuss the various efforts for therapeutic targeting of KRAS. Further, we explore the reasons behind these obstacles, novel successful approaches to target mutant KRAS including G12C mutation as well as the mechanisms of resistance.

On target: Rational approaches to KRAS inhibition for treatment of non-small cell lung carcinoma

Non-small cell lung carcinoma (NSCLC) is a leading cause of cancer death. Approximately one-third of patients with NSCLC have a KRAS mutation. KRAS^G12C, the most common mutation, is found in ~13% of patients. While KRAS was long considered 'undruggable', several novel direct KRAS^G12C inhibitors have shown encouraging signs of efficacy in phase I/II trials and one of these (sotorasib) has recently been approved by the US Food and Drug Administration. This review examines the role of KRAS mutations in NSCLC and the challenges in targeting KRAS. Based on specific KRAS biology, it reports exciting progress, exploring the use of novel direct KRAS inhibitors as monotherapy or in combination with other targeted therapies, chemotherapy, and immunotherapy.

Neutrophil-to-lymphocyte ratio is correlated to driver gene mutations in surgically-resected non-small cell lung cancer and its post-operative evolution impacts outcomes

BACKGROUND

We sought to evaluate prognostic value of neutrophil-to-lymphocyte ratio (NLR) in surgically resected non-small cell lung cancer (NSCLC) and its correlation to oncogenic drivers. We retrospectively reviewed data of patients who underwent anatomic lung resection for NSCLC and whose mutational status was known, from 4 department of thoracic surgery, over the period 2008 to 2019. Primary endpoints were overall survival (OS) and time to recurrence (TTR). Clinical and molecular factors were investigated in the univariate and multivariate analysis for their association with the primary endpoints.

RESULTS

2027 patients were included in the analysis. Correlations between NLR and OS (R²=0.21), NLR and TTR (R²=0.085) were significant (P<0.0001), with corresponding Pearson R of -0.46 (P<0.0001) and -0.292 (P<0.001), respectively. ROC curve analysis defined NLR cut-off value at 4.07. In the univariable analysis, the median OS was 66 months (95% CI: 62.94 - 69.06) in case of pre-operative NLR ≤ 4.07 and 38 months (95% CI: 36.73 - 39.27) in case of pre-operative NLR > 4.07 (P<0.0001), with corresponding 5-y OS of 72% and 29% respectively. Median TTR was associated with pre-operative NLR. Median TTR was 25 months (95% CI: 21.52 - 28.48) in case of pre-operative NLR ≤ 4.07 and 17 months (95% CI: 16.04 - 17.96) in case of pre-operative NLR > 4.07 (P<0.0001), with corresponding 5-years TTR of 18% and 9% respectively. Significant correlations between NLR >4.07 and KRAS (Cramer's V = 0.082, P < 0.0001) and EGFR mutations (Cramer's V = 0.064, P = 0.004) were observed.

CONCLUSIONS

Low pre-operative NLR is associated with longer OS in patients with resected NSCLC. Low pre-operative NLR is not associated with longer TTR in multivariate analysis. Correlation between the high NLR and KRAS/EGFR mutations were observed.

Endogenous and Therapeutic Estrogens: Maestro Conductors of the Microenvironment of ER+ Breast Cancers

Estrogen receptor alpha (ERα) marks heterogeneous breast cancers which display a repertoire of somatic genomic mutations and an immune environment that differs from other breast cancer subtypes. These cancers also exhibit distinct biological behaviors; despite an overall better prognosis than HER2+ or triple negative breast cancers, disseminated dormant cells can lead to disease recurrence decades after the initial diagnosis and treatment. Estrogen is the best studied driver of these cancers, and antagonism or reduction of estrogen activity is the cornerstone of therapeutic approaches. In addition to reducing proliferation of ERα+ cancer cells, these treatments also alter signals to multiple other target cells in the environment, including immune cell subpopulations, cancer-associated fibroblasts, and endothelial cells via several distinct estrogen receptors. In this review, we update progress in our understanding of the stromal cells populating the microenvironments of primary and metastatic ER+ tumors, the effects of estrogen on tumor and stromal cells to modulate immune activity and the extracellular matrix, and net outcomes in experimental and clinical studies. We highlight new approaches that will illuminate the unique biology of these cancers, provide the foundation for developing new treatment and prevention strategies, and reduce mortality of this disease.

The Importance of Being PI3K in the RAS Signaling Network

Ras proteins are essential mediators of a multitude of cellular processes, and its deregulation is frequently associated with cancer appearance, progression, and metastasis. Ras-driven cancers are usually aggressive and difficult to treat. Although the recent Food and Drug Administration (FDA) approval of the first Ras G12C inhibitor is an important milestone, only a small percentage of patients will benefit from it. A better understanding of the context in which Ras operates in different tumor types and the outcomes mediated by each effector pathway may help to identify additional strategies and targets to treat Ras-driven tumors. Evidence emerging in recent years suggests that both oncogenic Ras signaling in tumor cells and non-oncogenic Ras signaling in stromal cells play an essential role in cancer. PI3K is one of the main Ras effectors, regulating important cellular processes such as cell viability or resistance to therapy or angiogenesis upon oncogenic Ras activation. In this review, we will summarize recent advances in the understanding of Ras-dependent activation of PI3K both in physiological conditions and cancer, with a focus on how this signaling pathway contributes to the formation of a tumor stroma that promotes tumor cell proliferation, migration, and spread.

Beyond Microsatellite Instability: Evolving Strategies Integrating Immunotherapy for Microsatellite Stable Colorectal Cancer

OPINION STATEMENT

Advanced colorectal cancer (CRC) is a heterogeneous disease, characterized by several subtypes with distinctive genetic and epigenetic patterns. During the last years, immune checkpoint inhibitors (ICIs) have revamped the standard of care of several tumors such as non-small cell lung cancer and melanoma, highlighting the role of immune cells in tumor microenvironment (TME) and their impact on cancer progression and treatment efficacy. An "immunoscore," based on the percentage of two lymphocyte populations both at tumor core and invasive margin, has been shown to improve prediction of treatment outcome when added to UICC-TNM classification. To date, pembrolizumab, an anti-programmed death protein 1 (PD1) inhibitor, has gained approval as first-line therapy for mismatch-repair-deficient (dMMR) and microsatellite instability-high (MSI-H) advanced CRC. On the other hand, no reports of efficacy have been presented in mismatch-repair-proficient (pMMR) and microsatellite instability-low (MSI-L) or microsatellite stable (MSS) CRC. This group includes roughly 95% of all advanced CRC, and standard chemotherapy, in addition to anti-EGFR or anti-angiogenesis drugs, still represents first treatment choice. Hopefully, deeper understanding of CRC immune landscape and of the impact of specific genetic and epigenetic alterations on tumor immunogenicity might lead to the development of new drug combination strategies to overcome ICIs resistance in pMMR CRC, thus paving the way for immunotherapy even in this subgroup.

Drugging the Undruggable: Advances on RAS Targeting in Cancer

Around 20% of all malignancies harbour activating mutations in RAS isoforms. Despite this, there is a deficiency of RAS-targeting agents licensed for therapeutic use. The picomolar affinity of RAS for GTP, and the lack of suitable pockets for high-affinity small-molecule binding, precluded effective therapies despite decades of research. Recently, characterisation of the biochemical properties of KRAS-G12C along with discovery of its 'switch-II pocket' have allowed development of effective mutant-specific inhibitors. Currently seven KRAS-G12C inhibitors are in clinical trials and sotorasib has become the first one to be granted FDA approval. Here, we discuss historical efforts to target RAS directly and approaches to target RAS effector signalling, including combinations that overcome limitations of single-agent targeting. We also review pre-clinical and clinical evidence for the efficacy of KRAS-G12C inhibitor monotherapy followed by an illustration of combination therapies designed to overcome primary resistance and extend durability of response. Finally, we briefly discuss novel approaches to targeting non-G12C mutant isoforms.

Oncogenic KrasG12D Activation in the Nonhematopoietic Bone Marrow Microenvironment Causes Myelodysplastic Syndrome in Mice

The bone marrow microenvironment (BMME) is key player in regulation and maintenance of hematopoiesis. Oncogenic RAS mutations, causing constitutive activation of multiple tumor-promoting pathways, are frequently found in human cancer. So far in hematologic malignancies, RAS mutations have only been reported to occur in hematopoietic cells. In this study, we investigated the effect of oncogenic Kras expression in the BMME in a chimeric mouse model. We observed that an activating mutation of Kras in the nonhematopoietic system leads to a phenotype resembling myelodysplastic syndrome (MDS) characterized by peripheral cytopenia, marked dysplasia within the myeloid lineage as well as impaired proliferation and differentiation capacity of hematopoietic stem and progenitor cells. The phenotypic changes could be reverted when the BM was re-isolated and transferred into healthy recipients, indicating that the Kras^G12D -activation in the nonhematopoietic BMME was essential for the MDS phenotype. Gene expression analysis of sorted nonhematopoietic BM niche cells from Kras^G12D mice revealed upregulation of multiple inflammation-related genes including IL1-superfamily members (Il1α, Il1β, Il1f9) and the NLPR3 inflammasome. Thus, pro-inflammatory IL1-signaling in the BMME may contribute to MDS development. Our findings show that a single genetic change in the nonhematopoietic BMME can cause an MDS phenotype. Oncogenic Kras activation leads to pro-inflammatory signaling in the BMME which impairs HSPCs function. IMPLICATIONS: These findings may help to identify new therapeutic targets for MDS.

Melatonin Downregulates PD-L1 Expression and Modulates Tumor Immunity in KRAS-Mutant Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) patients harboring a KRAS mutation have unfavorable therapeutic outcomes with chemotherapies, and the mutation also renders tolerance to immunotherapies. There is an unmet need for a new strategy for overcoming immunosuppression in KRAS-mutant NSCLC. The recently discovered role of melatonin demonstrates a wide spectrum of anticancer impacts; however, the effect of melatonin on modulating tumor immunity is largely unknown. In the present study, melatonin treatment significantly reduced cell viability accompanied by inducing cell apoptosis in KRAS-mutant NSCLC cell lines including A549, H460, and LLC1 cells. Mechanistically, we found that lung cancer cells harboring the KRAS mutation exhibited a higher level of programmed death ligand 1 (PD-L1). However, treatment with melatonin substantially downregulated PD-L1 expressions in both the presence and absence of interferon (IFN)-γ stimulation. Moreover, KRAS-mutant lung cancer cells exhibited higher Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) levels, and PD-L1 expression was positively correlated with YAP and TAZ in lung cancer cells. Treatment with melatonin effectively suppressed YAP and TAZ, which was accompanied by downregulation of YAP/TAZ downstream gene expressions. The combination of melatonin and an inhibitor of YAP/TAZ robustly decreased YAP and PD-L1 expressions. Clinical analysis using public databases revealed that PD-L1 expression was positively correlated with YAP and TAZ in patients with lung cancer, and PD-L1 overexpression suggested poor survival probability. An animal study further revealed that administration of melatonin significantly inhibited tumor growth and modulated tumor immunity in a syngeneic mouse model. Together, our data revealed a novel antitumor mechanism of melatonin in modulating the immunosuppressive tumor microenvironment by suppressing the YAP/PD-L1 axis and suggest the therapeutic potential of melatonin for treating NSCLC.

Expression of Immuno-Oncologic Biomarkers Is Enriched in Colorectal Cancers and Other Solid Tumors Harboring the A59T Variant of KRAS

The molecular heterogeneity of KRAS is well established, with a pool of variants comprising >75% of all known mutations; this pool includes mutations in classic codons 12, 13, and 61, as well as 146 and 117. In addition, there are rare variants that are more frequently encountered clinically due to the advances in next-generation sequencing and more widespread implementation of All-RAS sequencing over the past five years. We have previously identified a missense variant of KRAS, A59T, in a patient with CRC that was associated with a response to an epidermal growth factor inhibitor when added to chemotherapy, supporting the hypothesis that distinct biochemical impacts of different KRAS mutations may produce varied responses to targeted therapy. In this study, we explored a large genomic database comprising 17,909 cases of CRC to determine the prevalence of the A59T mutation and characterized the concurrent genomic alterations associated with this variant in more detail, particularly in relation to the expanding set of potential predictive immuno-oncologic biomarkers. We identified 14 cases of A59 mutations in this dataset (0.08% prevalence). We evaluated the prevalence of high tumor mutation burden (TMB), positive PD-L1 expression, and microsatellite instability-high/mismatch repair-deficiency (MSI-H/dMMR) using both next generation sequencing (NGS) and immunohistochemistry (IHC). The genomic features of pertinent signaling pathways were also described, including RAS pathway, chromatin remodeling, DDR, hedgehog signaling, PI3K, receptor tyrosine kinases, signal transduction, TGF-beta, TP53, and WNT. We uncovered a high level of association of predictive markers of responsiveness to checkpoint inhibition and potentially other forms of immunotherapy, with nearly half of all cases harboring microsatellite instability as assessed using NGS. A59T was also detected in 11 additional cancer types, most prominently in cases of gynecologic or other gastrointestinal sites of origin. This study provides supportive evidence that A59T, and possibly other similarly rare KRAS variants, co-occur with predictive biomarkers of response to immunotherapy.

Inflammation-Induced Tumorigenesis and Metastasis

Inflammation, especially chronic inflammation, plays a pivotal role in tumorigenesis and metastasis through various mechanisms and is now recognized as a hallmark of cancer and an attractive therapeutic target in cancer. In this review, we discuss recent advances in molecular mechanisms of how inflammation promotes tumorigenesis and metastasis and suppresses anti-tumor immunity in various types of solid tumors, including esophageal, gastric, colorectal, liver, and pancreatic cancer as well as hematopoietic malignancies.

Targeting KRAS in Solid Tumors: Current Challenges and Future Opportunities of Novel KRAS Inhibitors

Activating mutations in RAS family proteins are found in ~25% of all human cancers. Different solid tumors are correlated with mutations in certain isoforms of RAS, with Kirsten RAS (KRAS) being the most frequently mutated isoform. Historically, KRAS has been acknowledged as “undruggable”, largely because the RAS proteins do not appear to present suitable pockets to which small inhibitory molecules can bind. However, this scenario has changed over the last years with the advent of novel KRAS inhibitors. In this review, we describe the role of KRAS mutation across different solid tumors, providing data on novel KRAS inhibitors currently under development and an updated overview of ongoing research in this field. A literature search was performed to select papers, abstracts, and oral presentation on KRAS inhibitory strategies in KRAS mutated solid tumors. Overall, the most promising therapeutic results have been obtained with molecules targeting KRAS G12C, thus paving the way for a significant therapeutic improvement in non-small cell lung cancer. Unfortunately, KRAS G12C mutation is rather uncommon in other solid tumors, namely pancreatic ductal adenocarcinoma and colorectal cancer. Several combination strategies are currently under evaluation in clinical trials, in order to bypass the resistance mechanisms responsible for the intrinsic resistance of mutated KRAS to the main therapeutic strategies adopted to date. Results suggest that the therapeutic scenario of KRAS has started to change, and further research will bring therapeutic results in this field.

Targeting BRAF and RAS in Colorectal Cancer

Simple Summary

In colorectal cancer, mutations of the KRAS and BRAF genes are quite common and can contribute to the activation of cell signaling pathways that lead to cell proliferation and differentiation. These processes promote cancer growth, and in some cases, they may cause cells to develop resistance to certain types of treatment, notably EGFR inhibitors. We summarize recent knowledge regarding the effects of KRAS and BRAF mutations in the setting of colorectal cancer and discuss the new therapies under development.

Abstract

Colorectal cancer (CRC) is still one of the most frequent forms of cancer in the world in terms of incidence. Around 40% of CRC patients carry a mutation of the Kirsten rat sarcoma (KRAS) gene, while 10% have a mutation in the B-Raf proto-oncogene serine/threonine kinase (BRAF) gene. These mutations are responsible for dysregulation of the mitogen-associated protein kinase (MAPK) pathway, leading to the proliferation, differentiation, angiogenesis, and resistance to apoptosis of cells. Activation of the MAPK pathway results in adaptive therapeutic resistance, rendering EGFR inhibitors ineffective. This review aims to highlight the recent findings that have improved our understanding of KRAS and BRAF mutations in colorectal cancer and to describe new targeted therapies, used alone or in combination.

Robust Prediction of Immune Checkpoint Inhibition Therapy for Non-Small Cell Lung Cancer

Background

The development of immune checkpoint inhibitors (ICIs) is a revolutionary milestone in the field of immune-oncology. However, the low response rate is the major problem of ICI treatment. The recent studies showed that response rate to single-agent programmed cell death protein 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) inhibition in unselected non-small cell lung cancer (NSCLC) patients is 25% so that researchers defined several biomarkers to predict the response of immunotherapy in ICIs treatment. Common biomarkers like tumor mutational burden (TMB) and PD-L1 expression have several limitations, such as low accuracy and inadequately validated cutoff value.

Methods

Two published and an unpublished ICIs treatment NSCLC cohorts with 129 patients were collected and divided into a training cohort (n = 53), a validation cohort (n = 22), and two independent test cohorts (n = 34 and n = 20). We identified six immune-related pathways whose mutational status was significantly associated with overall survival after ICIs treatment. Then these pathways mutational status combined with TMB, PD-L1 expression and intratumor heterogeneity were incorporated to build a Bayesian-regularization neural networks (BRNN) model to predict the ICIs treatment response.

Results

We firstly proved that TMB, PD-L1, and mutant-allele tumor heterogeneity (MATH) were independent biomarkers. The survival analysis of six immune-related pathways revealed the mutational status could distinguish overall survival after ICIs treatment. When predicting immunotherapy efficacy, the overall accuracy of area under curve (AUC) in validation cohort reaches 0.85, outperforming previous predictors in either sensitivity or specificity. And the AUC in two independent test cohorts reach 0.74 and 0.80.

Conclusion

We developed a pathway-model that could predict the efficacy of ICIs in NSCLC patients. Our study made a significant contribution to solving the low prediction accuracy of immunotherapy of single biomarker. With the accumulation of larger data sets, further studies are warranted to refine the predictive performance of the approach.

Karyotype Aberrations in Action: The Evolution of Cancer Genomes and the Tumor Microenvironment

Cancer is a disease of cellular evolution. For this cellular evolution to take place, a population of cells must contain functional heterogeneity and an assessment of this heterogeneity in the form of natural selection. Cancer cells from advanced malignancies are genomically and functionally very different compared to the healthy cells from which they evolved. Genomic alterations include aneuploidy (numerical and structural changes in chromosome content) and polyploidy (e.g., whole genome doubling), which can have considerable effects on cell physiology and phenotype. Likewise, conditions in the tumor microenvironment are spatially heterogeneous and vastly different than in healthy tissues, resulting in a number of environmental niches that play important roles in driving the evolution of tumor cells. While a number of studies have documented abnormal conditions of the tumor microenvironment and the cellular consequences of aneuploidy and polyploidy, a thorough overview of the interplay between karyotypically abnormal cells and the tissue and tumor microenvironments is not available. Here, we examine the evidence for how this interaction may unfold during tumor evolution. We describe a bidirectional interplay in which aneuploid and polyploid cells alter and shape the microenvironment in which they and their progeny reside; in turn, this microenvironment modulates the rate of genesis for new karyotype aberrations and selects for cells that are most fit under a given condition. We conclude by discussing the importance of this interaction for tumor evolution and the possibility of leveraging our understanding of this interplay for cancer therapy.

Persistent Inflammatory Stimulation Drives the Conversion of MSCs to Inflammatory CAFs That Promote Pro-Metastatic Characteristics in Breast Cancer Cells

The pro-inflammatory cytokines tumor necrosis factor α (TNFα) and interleukin 1β (IL-1β) are expressed simultaneously and have tumor-promoting roles in breast cancer. In parallel, mesenchymal stem cells (MSCs) undergo conversion at the tumor site to cancer-associated fibroblasts (CAFs), which are generally connected to enhanced tumor progression. Here, we determined the impact of consistent inflammatory stimulation on stromal cell plasticity. MSCs that were persistently stimulated by TNFα + IL-1β (generally 14-18 days) gained a CAF-like morphology, accompanied by prominent changes in gene expression, including in stroma/fibroblast-related genes. These CAF-like cells expressed elevated levels of vimentin and fibroblast activation protein (FAP) and demonstrated significantly increased abilities to contract collagen gels. Moreover, they gained the phenotype of inflammatory CAFs, as indicated by the reduced expression of α smooth muscle actin (αSMA), increased proliferation, and elevated expression of inflammatory genes and proteins, primarily inflammatory chemokines. These inflammatory CAFs released factors that enhanced tumor cell dispersion, scattering, and migration; the inflammatory CAF-derived factors elevated cancer cell migration by stimulating the chemokine receptors CCR2, CCR5, and CXCR1/2 and Ras-activating receptors, expressed by the cancer cells. Together, these novel findings demonstrate that chronic inflammation can induce MSC-to-CAF conversion, leading to the generation of tumor-promoting inflammatory CAFs.

CTLA-4 in Regulatory T Cells for Cancer Immunotherapy

Immune checkpoint inhibitors (ICIs) have obtained durable responses in many cancers, making it possible to foresee their potential in improving the health of cancer patients. However, immunotherapies are currently limited to a minority of patients and there is a need to develop a better understanding of the basic molecular mechanisms and functions of pivotal immune regulatory molecules. Immune checkpoint cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and regulatory T (Treg) cells play pivotal roles in hindering the anticancer immunity. Treg cells suppress antigen-presenting cells (APCs) by depleting immune stimulating cytokines, producing immunosuppressive cytokines and constitutively expressing CTLA-4. CTLA-4 molecules bind to CD80 and CD86 with a higher affinity than CD28 and act as competitive inhibitors of CD28 in APCs. The purpose of this review is to summarize state-of-the-art understanding of the molecular mechanisms underlining CTLA-4 immune regulation and the correlation of the ICI response with CTLA-4 expression in Treg cells from preclinical and clinical studies for possibly improving CTLA-4-based immunotherapies, while highlighting the knowledge gap.

Pancreatic cancer driver mutations are targetable through distant alternative RNA splicing dependencies

Pancreatic ductal adenocarcinoma (PDAC), the most common histological subtype of pancreatic cancer, has one of the highest case fatality rates of all known solid malignancies. Over the past decade, several landmark studies have established mutations in KRAS and TP53 as the predominant drivers of PDAC pathogenesis and therapeutic resistance, though treatment options for PDACs and other tumors with these mutations remain extremely limited. Hampered by late tumor discovery and diagnosis, clinicians are often faced with using aggressive and non-specific chemotherapies to treat advanced disease. Clinically meaningful responses to targeted therapy are often limited to the minority of patients with susceptible PDACs, and immunotherapies have routinely encountered roadblocks in effective activation of tumor-infiltrating immune cells. Alternative RNA splicing (ARS) has recently gained traction in the PDAC literature as a field from which we may better understand and treat complex mechanisms of PDAC initiation, progression, and therapeutic resistance. Here, we review PDAC pathogenesis as it relates to fundamental ARS biology, with an extension to implications for PDAC patient clinical management.

Turning cold tumors into hot tumors by improving T-cell infiltration

Immunotherapy, represented by immune checkpoint inhibitors (ICIs), has greatly improved the clinical efficacy of malignant tumor therapy. ICI-mediated antitumor responses depend on the infiltration of T cells capable of recognizing and killing tumor cells. ICIs are not effective in "cold tumors", which are characterized by the lack of T-cell infiltration. To realize the full potential of immunotherapy and solve this obstacle, it is essential to understand the drivers of T-cell infiltration into tumors. We present a critical review of our understanding of the mechanisms underlying “cold tumors”, including impaired T-cell priming and deficient T-cell homing to tumor beds. “Hot tumors” with significant T-cell infiltration are associated with better ICI efficacy. In this review, we summarize multiple strategies that promote the transformation of "cold tumors" into “hot tumors” and discuss the mechanisms by which these strategies lead to increased T-cell infiltration. Finally, we discuss the application of nanomaterials to tumor immunotherapy and provide an outlook on the future of this emerging field. The combination of nanomedicines and immunotherapy enhances cross-presentation of tumor antigens and promotes T-cell priming and infiltration. A deeper understanding of these mechanisms opens new possibilities for the development of multiple T cell-based combination therapies to improve ICI effectiveness.

Signaling pathways in intestinal homeostasis and colorectal cancer: KRAS at centre stage

The intestinal epithelium acts as a physical barrier that separates the intestinal microbiota from the host and is critical for preserving intestinal homeostasis. The barrier is formed by tightly linked intestinal epithelial cells (IECs) (i.e. enterocytes, goblet cells, neuroendocrine cells, tuft cells, Paneth cells, and M cells), which constantly self-renew and shed. IECs also communicate with microbiota, coordinate innate and adaptive effector cell functions. In this review, we summarize the signaling pathways contributing to intestinal cell fates and homeostasis functions. We focus especially on intestinal stem cell proliferation, cell junction formation, remodelling, hypoxia, the impact of intestinal microbiota, the immune system, inflammation, and metabolism. Recognizing the critical role of KRAS mutants in colorectal cancer, we highlight the connections of KRAS signaling pathways in coordinating these functions. Furthermore, we review the impact of KRAS colorectal cancer mutants on pathway rewiring associated with disruption and dysfunction of the normal intestinal homeostasis. Given that KRAS is still considered undruggable and the development of treatments that directly target KRAS are unlikely, we discuss the suitability of targeting pathways downstream of KRAS as well as alterations of cell extrinsic/microenvironmental factors as possible targets for modulating signaling pathways in colorectal cancer.

The Combination of Neutrophil-Lymphocyte Ratio and Platelet-Lymphocyte Ratio with Liquid Biopsy Biomarkers Improves Prognosis Prediction in Metastatic Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with a highly inflammatory microenvironment and liquid biopsy has emerged as a promising tool for the noninvasive analysis of this tumor. In this study, plasma was obtained from 58 metastatic PDAC patients, and neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), circulating cell-free DNA (cfDNA) concentration, and circulating RAS mutation were determined. We found that NLR was significantly associated with both overall survival (OS) and progression-free survival. Remarkably, NLR was an independent risk factor for poor OS. Moreover, NLR and PLR positively correlated, and combination of both inflammatory markers significantly improved the prognostic stratification of metastatic PDAC patients. NLR also showed a positive correlation with cfDNA levels and RAS mutant allelic fraction (MAF). Besides, we found that neutrophil activation contributed to cfDNA content in the plasma of metastatic PDAC patients. Finally, a multi-parameter prognosis model was designed by combining NLR, PLR, cfDNA levels, RAS mutation, RAS MAF, and CA19-9, which performs as a promising tool to predict the prognosis of metastatic PDAC patients. In conclusion, our study supports the idea that the use of systemic inflammatory markers along with circulating tumor-specific markers may constitute a valuable tool for the clinical management of metastatic PDAC patients.

The i-Motif as a Molecular Target: More Than a Complementary DNA Secondary Structure

Stretches of cytosine-rich DNA are capable of adopting a dynamic secondary structure, the i-motif. When within promoter regions, the i-motif has the potential to act as a molecular switch for controlling gene expression. However, i-motif structures in genomic areas of repetitive nucleotide sequences may play a role in facilitating or hindering expansion of these DNA elements. Despite research on the i-motif trailing behind the complementary G-quadruplex structure, recent discoveries including the identification of a specific i-motif antibody are pushing this field forward. This perspective reviews initial and current work characterizing the i-motif and providing insight into the biological function of this DNA structure, with a focus on how the i-motif can serve as a molecular target for developing new therapeutic approaches to modulate gene expression and extension of repetitive DNA.

Comprehensive analysis to identify DLEU2L/TAOK1 axis as a prognostic biomarker in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the deadliest malignant tumors that are harmful to human health. Increasing evidence has underscored the critical role of the competitive endogenous RNA (ceRNA) regulatory networks among various human cancers. However, the complexity and behavior characteristics of the ceRNA network in HCC were still unclear. In this study, we aimed to clarify a phosphatase and tensin homolog (PTEN)-related ceRNA regulatory network and identify potential prognostic markers associated with HCC. The expression profiles of three RNAs (long non-coding RNAs [lncRNAs], microRNAs [miRNAs], and mRNAs) were extracted from The Cancer Genome Atlas (TCGA) database. The DLEU2L-hsa-miR-100-5p/ hsa-miR-99a-5p-TAOK1 ceRNA network related to the prognosis of HCC was obtained by performing bioinformatics analysis. Importantly, we identified the DLEU2L/TAOK1 axis in the ceRNA by using correlation analysis, and it appeared to become a clinical prognostic model by Cox regression analysis. Furthermore, methylation analyses suggested that the abnormal upregulation of the DLEU2L/TAOK1 axis likely resulted from hypomethylation, and immune infiltration analysis showed that the DLEU2L/TAOK1 axis may have an impact on the changes in the tumor immune microenvironment and the development of HCC. In summary, the current study constructing a ceRNA-based DLEU2L/TAOK1 axis might be a novel important prognostic factor associated with the diagnosis and prognosis of HCC.

Small-Molecule Inhibitors Directly Targeting KRAS as Anticancer Therapeutics

KRAS, the most frequently mutated oncogene, plays a predominant role in driving initiation and progression of cancers. Decades of effort to target KRAS using small molecules has been unsuccessful, causing KRAS to be considered an "undruggable" cancer target. However, this view began to change recently, as drug discovery techniques have developed several KRAS G12C allosteric inhibitors that are currently being evaluated in clinical trials. Herein we provide an in-depth analysis of the structure and binding pockets of KRAS, medicinal chemistry optimization processes, and the biological characterization of small-molecule inhibitors that directly target KRAS, including covalent allosteric inhibitors specific for the G12C mutant, GTP-competitive inhibitors targeting the nucleotide-binding site, and protein-protein interaction inhibitors that bind in the switch I/II pocket or the A59 site. Additionally, we propose potential challenges faced by these new classes of KRAS inhibitors under clinical evaluation.