Significance of RAS mutations in pulmonary metastases of patients with colorectal cancer

Prognostic value and immune infiltration of novel signatures in colon cancer microenvironment

Background

Growing evidence has shown that the prognosis for colon cancer depends on changes in microenvironment. The purpose of this study was to elucidate the prognostic value of long noncoding RNAs (lncRNAs) related to immune microenvironment (IM) in colon cancer.

Methods

Single sample gene set enrichment analysis (ssGSEA) was used to identify the subtypes of colon cancer based on the immune genomes of 29 immune signatures. Cox regression analysis identified a lncRNA signatures associated with immune infiltration. The Tumor Immune Estimation Resource database was used to analyze immune cell content.

Results

Colon cancer samples were divided into three subtypes by unsupervised cluster analysis. Cox regression analysis identified an immune infiltration-related 5-lncRNA signature. This signature combined with clinical factors can effectively improve the predictive ability for the overall survival (OS) of colon cancer. At the same time, we found that the expression of H19 affects the content of B cells and macrophages in the microenvironment of colon cancer and affects the prognosis of colon cancer. Finally, we constructed the H19 regulatory network and further analyzed the possible mechanisms. We found that knocking down the expression of H19 can significantly inhibit the expression of CCND1 and VEGFA. At the same time, the immunohistochemical assay found that the expression of CCND1 and VEGFA protein was significantly positively correlated with the infiltration of M2 type macrophages.

Conclusion

The findings may help to formulate clinical strategies and understand the underlying mechanisms of H19 regulation. H19 may be a biomarker for targeted treatment of colon cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02342-8.

Pulmonary metastasectomy in colorectal carcinoma

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. It is estimated that 50% of all patients with CRC develop metastases, most commonly in the liver and the lung. Lung metastases are seen in approximately 10–15% of all patients with CRC. A large number of these patients with metastatic CRC can only receive palliative treatment due to invasion of other organs and disseminated disease. However, a subset of these patients present with potentially resectable metastases. Pulmonary metastasectomy is considered to be a potentially curative treatment for selected patients with resectable metastatic CRC. Current data suggest that patients that undergo pulmonary metastasectomy have 5-year survival rates of approximately 40%. However, the majority of data published regarding lung metastasectomy is based on small, retrospective case series. Due to this lack of prospective data, it is still unclear which subset of patients will benefit most from curative-intent surgery. Furthermore, there is also controversy regarding which prognostic and genetic factors are related to survival outcomes and whether there is a difference between open and thoracoscopic approaches in terms of overall and disease-free survival. In this review, we aim to summarize the latest data on prognostic factors and survival outcomes after pulmonary metastasectomy in patients with metastatic CRC.

Histological growth patterns and molecular analysis of resected colorectal lung metastases

Lung is the site of metastasis in about 15-25 % of colorectal cancer (CRC) patients. Lung metastasectomy of CRC represents a standard therapy in patients with resectable metastases. In this study we investigated both histological patterns of metastases and mutations in MAPkinase pathway genes and their relationship to prognosis. The study included 74 patients that underwent metastasectomy of colorectal lung metastasis (CLM). In patients that underwent surgical resection of more than one metastasis in the same operation the largest was chosen. In patients that had undergone multiple lung metastasectomy only the sample from the first metastasectomy was included. Histologically metastases were scored according to amount and distribution of necrosis and fibrosis and three patterns were identified: "pattern A", metastasis with extensive, confluent central necrosis surrounded by a rim of neoplastic glands; "pattern B", metastasis characterized by a proliferation of neoplastic glands in a dense stroma with focal necrosis mainly intraglandular; "pattern C", metastasis with a mixed A and B morphology. In all samples direct sequencing of exon 2 of KRAS and NRAS genes and exon 15 of BRAF genes was carried out.Histological patterns weren't related to metastasis size or other clinical features however pattern C metastases showed a significant worst disease free survival (DFS). KRAS mutations were observed in 39 % of patients. Mutations in KRAS codon 13 resulted significantly associated with synchronous metastasis and poor prognosis. No mutations were identified in exon 2 NRAS gene whilst 1.4 % harboured a mutation in BRAF. To our knowledge this is the first study that investigates in a large series of CLM histological growth patterns, molecular alterations and their relationship to prognosis. Our data suggest a prognostic role in CLM of KRAS specific mutations and histopathological patterns.