Cell Type-Specific Roles of STAT3 Signaling in the Pathogenesis and Progression of K-ras Mutant Lung Adenocarcinoma

A novel cancer-associated fibroblasts risk score model predict survival and immunotherapy in lung adenocarcinoma

Lung adenocarcinoma (LUAD) is the leading cause of cancer-related death worldwide. Cancer-associated fibroblasts (CAFs) are a special type of fibroblasts, which play an important role in the development and immune escape of tumors. Weighted gene co-expression network analysis (WGCNA) was used to construct the co-expression module. In combination with univariate Cox regression and analysis of least absolute shrinkage operator (LASSO), characteristics associated with CAFs were developed for a prognostic model. The migration and proliferation of lung cancer cells were evaluated in vitro. Finally, the expression levels of proteins were analyzed by Western blot. LASSO Cox regression algorithm was then performed to select hub genes. Finally, a total of 2 Genes (COL5A2, COL6A2) were obtained. We then divided LUAD patients into high- and low-risk groups based on CAFs risk scores. Survival analysis, CAFs score correlation analysis and tumor mutation load analysis showed that COL5A2 and COL6A2 were high-risk genes for LUAD. Human Protein Atlas (HPA), western blot and PCR results showed that COL5A2 and COL6A2 were up-regulated in LUAD tissues. When COL5A2 and COL6A2 were knocked down, the proliferation, invasion and migration of lung cancer cells were significantly decreased. Finally, COL5A2 can affect LUAD progression through the Wnt/β-Catenin and TGF-β signaling pathways. Our CAFs risk score model offers a new approach for predicting the prognosis of LUAD patients. Furthermore, the identification of high-risk genes COL5A2 and COL6A2 and drug sensitivity analysis can provide valuable candidate clues for clinical treatment of LUAD.

Dihydroartemisinin inhibits tumor progress via blocking ROR1-induced STAT3-activation in non-small cell lung cancer

In non-small cell lung cancer (NSCLC), identifying a component with certain molecular targets can aid research on cancer treatment. Dihydroartemisinin (DHA) is a semisynthetic derivative of artemisinin which induced the anti-cancer effects via the STAT3 signaling pathway, but the underlying molecular mechanism is still elusive. In this study, we first proved that DHA prohibits the growth of tumors both in vitro and in vivo. Data from transcriptomics showed that DHA reduced the expression level of the genes involved in cell cycle-promoting and anti-apoptosis, and most importantly, DHA restricted the expression level of receptor tyrosine kinase-like orphan receptor 1 (ROR1) which has been reported to have abnormal expression on tumor cells and had close interaction with STAT3 signaling. Then, we performed comprehensive experiments and found that DHA remarkably decreased the expression of ROR1 at both mRNA and protein levels and it also diminished the phosphorylation level of STAT3 in NSCLC cell lines. In addition, our data showed that exogenously introduced ROR1 could significantly enhance the phosphorylation of STAT3 while blocking ROR1 had the opposite effects indicating that ROR1 plays a critical role in promoting the activity of STAT3 signaling. Finally, we found that ROR1 overexpression could partially reverse the decreased activity of STAT3 induced by DHA which indicates that DHA-induced anti-growth signaling is conferred, at least in part, through blocking ROR1-mediated STAT3 activation. In summary, our study indicates that in NSCLC, ROR1 could be one of the critical molecular targets mediating DHA-induced STAT3 retardation.

Activity and resistance to KRASG12C inhibitors in non-small cell lung cancer and colorectal cancer

Non-small cell lung cancer (NSCLC) and colorectal cancer (CRC) are associated with a high mortality rate. Mutations in the V-Ki-ras2 Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) proto-oncogene GTPase (KRAS) are frequently observed in these cancers. Owing to its structural attributes, KRAS has traditionally been regarded as an "undruggable" target. However, recent advances have identified a novel mutational regulatory site, KRASG12C switch II, leading to the development of two KRASG12C inhibitors (adagrasib and sotorasib) that are FDA-approved. This groundbreaking discovery has revolutionized our understanding of the KRAS locus and offers treatment options for patients with NSCLC harboring KRAS mutations. Due to the presence of alternative resistance pathways, the use of KRASG12C inhibitors as a standalone treatment for patients with CRC is not considered optimal. However, the combination of KRASG12C inhibitors with other targeted drugs has demonstrated greater efficacy in CRC patients harboring KRAS mutations. Furthermore, NSCLC and CRC patients harboring KRASG12C mutations inevitably develop primary or acquired resistance to drug therapy. By gaining a comprehensive understanding of resistance mechanisms, such as secondary mutations of KRAS, mutations of downstream intermediates, co-mutations with KRAS, receptor tyrosine kinase (RTK) activation, Epithelial-Mesenchymal Transitions (EMTs), and tumor remodeling, the implementation of KRASG12C inhibitor-based combination therapy holds promise as a viable solution. Furthermore, the emergence of protein hydrolysis-targeted chimeras and molecular glue technologies has been facilitated by collaborative efforts in structural science and pharmacology. This paper aims to provide a comprehensive review of the recent advancements in various aspects related to the KRAS gene, including the KRAS signaling pathway, tumor immunity, and immune microenvironment crosstalk, as well as the latest developments in KRASG12C inhibitors and mechanisms of resistance. In addition, this study discusses the strategies used to address drug resistance in light of the crosstalk between these factors. In the coming years, there will likely be advancements in the development of more efficacious pharmaceuticals and targeted therapeutic approaches for treating NSCLC and CRC. Consequently, individuals with KRAS-mutant NSCLC may experience a prolonged response duration and improved treatment outcomes.

NSUN2 promotes lung adenocarcinoma progression through stabilizing PIK3R2 mRNA in an m5C-dependent manner

It is well known that 5-methylcytosine (m5C) is involved in variety of crucial biological processes in cancers. However, its biological roles in lung adenocarcinoma (LAUD) remain to be determined. The LUAD samples were used to assess the clinical value of NOP2/Sun RNA Methyltransferase 2 (NSUN2). Dot blot was used to determine global m5C levels. ChIP and dual-luciferase assays were performed to investigate the MYC-associated zinc finger protein (MAZ)-binding sites in NSUN2 promoter. RNA-seq was used to explore the downstream molecular mechanisms of NSUN2. Dual luciferase reporter assay, m5C-RIP-qPCR, and mRNA stability assay were conducted to explore the effect of NSUN2-depletion on target genes. Cell viability, transwell, and xenograft mouse model were designed to demonstrate the characteristic of NSUN2 in promoting LUAD progression. The m5C methyltransferase NSUN2 was highly expressed and caused elevated m5C methylation in LUAD samples. Mechanistically, MAZ positively regulated the transcription of NSUN2 and was related to poor survival of LUAD patients. Silencing NSUN2 decreased the global m5C levels, suppressed proliferation, migration and invasion, and inhibited activation of PI3K-AKT signaling in A549 and SPAC-1 cells. Phosphoinositide-3-Kinase Regulatory Subunit 2 (PIK3R2) was upregulated by NSUN2-mediated m5C methylation by enhancing its mRNA stabilization and activated the phosphorylation of the PI3K-AKT signaling. The present study explored the underlying mechanism and biological function of NSUN2-meditated m5C RNA methylation in LUAD. NSUN2 was discovered to facilitate the malignancy progression of LUAD through regulating m5C modifications to stabilize PIK3R2 activating the PI3K-AKT signaling, suggesting that NSUN2 could be a novel biomarker and promising therapeutic target for LUAD patients.

Single-cell RNA sequencing reveals the mechanism of PI3K/AKT/mTOR signaling pathway activation in lung adenocarcinoma by KRAS mutation

BACKGROUND

Aberrant activation of the phosphatidlinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway has been shown to play an important role in lung adenocarcinoma (LUAD). The effect of KRAS mutations, one of the important signatures of LUAD, on the PI3K/AKT/mTOR pathway in LUAD remains unclear.

METHODS

The Seurat package and principal component analysis were used for cell categorization of single-cell RNA sequencing data of LUAD. The AUCell score was used to assess the activity of the PI3K/AKT/mTOR pathway. Meanwhile, using the gene expression profiles and mutation profiles in the The Cancer Genome Atlas dataset, LUAD patients were categorized into KRAS-mutant (KRAS-MT) and KRAS-wild-types (KRAS-WT), and the corresponding enrichment scores were calculated using gene set enrichment analysis analysis. Finally, the subpopulation of cells with the highest pathway activity was identified, the copy number variation profile of this subpopulation was inscribed using the inferCNV package and the CMap database was utilized to make predictions for drugs targeting this subpopulation.

RESULTS

There is higher PI3K/AKT/mTOR pathway activity in LUAD epithelial cells with KRAS mutations, and high expression of KRAS, PIK3CA, AKT1 and PDPK1. In particular, we found significantly higher levels of pathway activity and associated gene expression in KRAS-MT than in KRAS-WT. We identified the highest pathway activity on a subpopulation of GRB2+ epithelial cells and the presence of amplified genes within its pathway. Finally, drugs were able to target GRB2+ epithelial cell subpopulations, such as wortmannin, palbociclib and angiogenesis inhibitor.

CONCLUSIONS

The present study provides a basic theory for the activation of the PI3K/AKT/mTOR signaling pathway as a result of KRAS mutations.

From targeted therapy to a novel way: Immunogenic cell death in lung cancer

Lung cancer (LC) is one of the most incident malignancies and a leading cause of cancer mortality worldwide. Common tumorigenic drivers of LC mainly include genetic alterations of EGFR, ALK, KRAS, BRAF, ROS1, and MET. Small inhibitory molecules and antibodies selectively targeting these alterations or/and their downstream signaling pathways have been approved for treatment of LC. Unfortunately, following initial positive responses to these targeted therapies, a large number of patients show dismal prognosis due to the occurrence of resistance mechanisms, such as novel mutations of these genes and activation of alternative signaling pathways. Over the past decade, it has become clear that there is no possible cure for LC unless potent antitumor immune responses are induced by therapeutic intervention. Immunogenic cell death (ICD) is a newly emerged concept, a form of regulated cell death that is sufficient to activate adaptive immune responses against tumor cells. It transforms dying cancer cells into a therapeutic vaccine and stimulates long-lasting protective antitumor immunity. In this review, we discuss the key targetable genetic aberrations and the underlying mechanism of ICD in LC. Various agents inducing ICD are summarized and the possibility of harnessing ICD in LC immunotherapy is further explored.