Regulation of KRAS protein expression by miR-544a and KRAS-LCS6 polymorphism in wild-type KRAS sporadic colon adenocarcinoma

The relationship of KRAS expression with KRAS status, prognosis, and tumor-infiltrated T lymphocytes in colorectal cancer

Background

The significance of Kirsten rat sarcoma viral oncogene (KRAS) mutation in colorectal cancer (CRC) is well established; yet, its association with KRAS expression and prognosis warrants further investigation. While high KRAS expression is commonly linked with poorer prognosis in other cancers, its role in CRC remains relatively understudied.

Objective

To explore the correlation between KRAS expression, KRAS status, prognosis, and tumor-infiltrating T lymphocyte density in CRC.

Design

Single-center retrospective study.

Methods

Conducted between 2010 and 2020, this study utilized tumor samples to assess KRAS expression and quantify CD3+/CD8+ T lymphocytes. The Cox proportional hazards model and linear regression analysis were employed to examine the relationship between KRAS expression, prognosis, and tumor-infiltrating T lymphocytes.

Results

This study included 265 CRC patients who underwent radical surgery. No significant association was observed between KRAS expression and KRAS status (p > 0.05). High KRAS expression was associated with poorer overall survival and disease-free survival (p < 0.05). Subgroup analysis revealed that high KRAS expression remained indicative of a worse prognosis in the group with mismatch repair-deficient (dMMR) and KRAS mutant type (p < 0.05). Multivariate analysis confirmed KRAS expression as an unfavorable prognostic factor (p < 0.05). However, the significance of KRAS expression was lost in the dMMR and KRAS mutant-type group regarding overall survival (p > 0.05). Notably, KRAS expression showed a negative correlation with the density of CD8+ T lymphocytes in tumor tissue (p < 0.05), a finding also observed in the dMMR group (p < 0.05).

Conclusion

No association was found between KRAS expression and KRAS mutation status in CRC. Higher KRAS expression was indicative of poorer prognosis for CRC patients, except for those with proficient mismatch repair and KRAS wild type. In addition, in patients with dMMR, KRAS expression was associated with a lower density of CD8+ T lymphocytes in tumor tissue.

Research progress on small molecule inhibitors targeting KRAS G12C with acrylamide structure and the strategies for solving KRAS inhibitor resistance

KRAS (Kirsten-RAS) is a highly mutated gene in the RAS (rat sarcoma) gene family that acts as a critical switch in intracellular signaling pathways, regulating cell proliferation, differentiation, and survival. The continuous activation of KRAS protein resulting from mutations leads to the activation of multiple downstream signaling pathways, inducing the development of malignant tumors. Despite the significant role of KRAS in tumorigenesis, targeted drugs against KRAS gene mutations have failed, and KRAS was once considered an undruggable target. The development of KRAS G12C mutant conformational modulators and the introduction of Sotorasib (R&D code: AMG510) have been a breakthrough in this field, with its remarkable clinical outcomes. Consequently, there is now a great number of KRAS G12C mutations. Patent applications for mutant GTPase KRAS G12C inhibitors, which are said to be covalently modified by cysteine codon 12, have been submitted since 2014. This review classifies KRAS G12C inhibitors based on their chemical structure and evaluates their biological properties. Additionally, it discusses the obstacles encountered in KRAS inhibitor research and the corresponding solutions.