Untangling the KRAS mutated lung cancer subsets and its therapeutic implications

Salvianolic acid F suppresses KRAS-dependent lung cancer cell growth through the PI3K/AKT signaling pathway

BACKGROUND

KRAS mutation is a common driver of NSCLC, and there is a high proportion of lung cancer patients with KRAS G12C and G12D mutation. KRAS was previously considered an "undruggable" target, but the first KRAS G12C mutation-targeted drug AMG510, entered the market in 2021. However, treatments for G12D mutant tumors remain to be discovered. Salvianolic acid F (SalF), a monomer derived from the traditional Chinese medicine Salvia miltiorrhiza (SM), and KRAS had high binding affinity, especially for KRAS G12D. There is an urgent need to investigate effective and safe novel targeted therapies against KRAS G12D-driven NSCLC.

METHODS

To evaluate the anticancer effect of SalF, we used KRAS-overexpressing lung cancer cells in vitro, a subcutaneous transplant tumor model, and KRAS G12D mice model in vivo. Then, the binding effect of SalF and KRAS was investigated using molecular docking, proteolytic assays and protein thermal shift assays. More critically, the PI3K/AKT signaling pathway in the lung was investigated utilizing RT-qPCR and Western Blotting.

RESULTS

This is the first study to evaluate the anticancer effect of SalF on KRAS-overexpressing lung cancer cells or KRAS G12D lung tumors in vivo. We demonstrated that SalF inhibits OE-KRAS A549 cell migration, proliferation and promotes apoptosis in vitro. In addition, we used a subcutaneous transplant tumor model to show that SalF suppresses the growth of lung cancer cells in vivo. Interestingly, our group found that SalF was strongly bound to G12D and could decrease the stability and promoted the degradation of the KRAS G12D mutant through molecular docking, proteolytic assays and protein thermal shift assays. Further research demonstrated that in the KrasG12D mice model, after SalF treatment, the number and size of mouse lung tumors were significantly reduced. More importantly, SalF can promote apoptosis by inhibiting downstream PI3K/AKT signaling pathway activation.

CONCLUSION

SalF activated apoptosis signaling pathways, suppressed anti-apoptotic genes, and inhibited lung cancer cell growth. These datas suggested that SalF could effectively inhibit the growth of lung tumors with KRAS G12D mutation. SalF may be a novel inhibitor against KRAS G12D, providing a strong theoretical basis for the clinical treatment of lung cancer with KRAS mutations.

Canadian Consensus Recommendations on the Management of KRAS G12C-Mutated NSCLC

Activating mutations in Kirsten rat sarcoma viral oncogene homologue (KRAS), in particular, a point mutation leading to a glycine-to-cysteine substitution at codon 12 (G12C), are among the most frequent genomic alterations in non-small cell lung cancer (NSCLC). Several agents targeting KRAS G12C have recently entered clinical development. Sotorasib, a first-in-class specific small molecule that irreversibly inhibits KRAS G12C, has since obtained Health Canada approval. The emergence of novel KRAS-targeted therapies warrants the development of evidence-based consensus recommendations to help clinicians better understand and contextualize the available data. A Canadian expert panel was convened to define the key clinical questions, review recent evidence, and discuss and agree on recommendations for the treatment of advanced KRAS G12C-mutated NSCLC. The panel agreed that testing for KRAS G12C should be performed as part of a comprehensive panel that includes current standard-of-care biomarkers. Sotorasib, the only approved KRAS G12C inhibitor in Canada, is recommended for patients with advanced KRAS G12C-mutated NSCLC who progressed on guideline-recommended first-line standard of care for advanced NSCLC without driver alterations (immune-checkpoint inhibitor(s) [ICIs] +/- chemotherapy). Sotorasib could also be offered as second-line therapy to patients who progressed on ICI monotherapy that are not candidates for a platinum doublet and those that received first-line chemotherapy with a contraindication to ICIs. Preliminary data indicate the activity of KRAS G12C inhibitors in brain metastases; however, the evidence is insufficient to make specific recommendations. Regular liver function monitoring is recommended when patients are prescribed KRAS G12C inhibitors due to risk of hepatotoxicity.

Glutathione peroxidase 8 expression on cancer cells and cancer-associated fibroblasts facilitates lung cancer metastasis

Lung cancer is the leading cause of cancer death worldwide, of which lung adenocarcinoma (LUAD) is the most common subtype. Metastasis is the major cause of poor prognosis and mortality for lung cancer patients, which urgently needs great efforts to be further explored. Herein, glutathione peroxidase 8 (GPX8) was identified as a novel potential pro-metastatic gene in LUAD metastatic mice models from GEO database. GPX8 was highly expressed in tumor tissues, predicting poor prognosis in LUAD patients. Knockdown of GPX8 inhibited LUAD metastasis in vitro and in vivo, while it did not obviously affect tumor growth. Knockdown of GPX8 decreased the levels of p-FAK and p-Paxillin and disturbed the distribution of focal adhesion. Furthermore, GPX8 was overexpressed in cancer-associated fibroblast (CAF) and associated with CAF infiltration in tumor microenvironment of lung cancer. GPX8 silence on fibroblasts suppressed lung cancer cell migration in the coculture system. BRD2 and RRD4 were the potential transcriptionally regulators for GPX8. Bromodomain extra-terminal inhibitor JQ1 downregulated GPX8 expression and suppressed lung cancer cell migration. Our findings indicate that highly expressed GPX8 in lung cancer cells and fibroblasts functions as a pro-metastatic factor in lung cancer. JQ1 is identified as a potential inhibitor against GPX8-mediated lung cancer metastasis.