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Effective biomarkers play a critical role in improving clinical approaches to treat lung adenocarcinoma (LUAD). However, many existing biomarkers have limitations due to a lot of factors, requiring the development of additional biomarkers to effectively predict the disease course and prognosis of LUAD. Guanine-rich RNA sequence binding factor 1 (GRSF1) participates in multiple biological processes, but its regulatory effect on LUAD remains unknown. The present study aimed to investigate the clinicopathological importance and biological role of GRSF1 in LUAD.The expression of GRSF1 was evaluated using multiple service portals. X-Tile software were used to determine the high and low GRSF1 groups and the relationships between GRSF1 expression and clinicopathological characteristics were then analyzed by R packages. Besides, prognostic significance was identified by the Gene Expression Profiling Interactive Analysis 2 (GEPIA2) and Kaplan-Meier (K-M) Plotter. Overall survival (OS) and disease-free survival (DFS) was the main outcome of prognosis analysis. The DNA copy number alterations (CNAs) and methylations were calculated using cBioPortal and R packages. The co-expressed genes of GRSF1 were obtained from LinkedOmics, and functional networks were then constructed by R clusterProfiler. Additionally, cell counting kit 8 (CCK-8) and colony formation assays were applied to verify the proliferation effects of GRSF1 on LUAD cells.GRSF1 was significantly upregulated in the LUAD tissues compared to the non-tumor lung tissues (all P0.05), and its expression was significantly correlated with gender (χThe high expression of GRSF1 indicated an unfavorable prognosis and was closely related to LUAD tumor occurrence and development, which could be used as an effective prognostic biomarker for patients suffering from LUAD.

Background Colorectal cancer (CRC) is one of the most common malignancies, and it’s expected that the CRC burden will substantially increase in the next two decades. New biomarkers for targeted treatment and associated molecular mechanism of tumorigenesis remain to be explored. In this study, we investigated whether PDCD6 plays an oncogenic role in colorectal cancer and its underlying mechanism. Methods Programmed cell death protein 6 (PDCD6) expression in CRC samples were analyzed by immunohistochemistry and immunofluorescence. The prognosis between PDCD6 and clinical features were analyzed. The roles of PDCD6 in cellular proliferation and tumor growth were measured by using CCK8, colony formation, and tumor xenograft in nude mice. RNA-sequence (RNA-seq), Mass Spectrum (MS), Co-Immunoprecipitation (Co-IP) and Western blot were utilized to investigate the mechanism of tumor progression. Immunohistochemistry (IHC) and quantitative real-time PCR (qRT-PCR) were performed to determine the correlation of PDCD6 and MAPK pathway. Results Higher expression levels of PDCD6 in tumor tissues were associated with a poorer prognosis in patients with CRC. Furthermore, PDCD6 increased cell proliferation in vitro and tumor growth in vivo. Mechanistically, RNA-seq showed that PDCD6 could affect the activation of the MAPK signaling pathway. PDCD6 interacted with c-Raf, resulting in the activation of downstream c-Raf/MEK/ERK pathway and the upregulation of core cell proliferation genes such as MYC and JUN. Conclusions These findings reveal the oncogenic effect of PDCD6 in CRC by activating c-Raf/MEK/ERK pathway and indicate that PDCD6 might be a potential prognostic indicator and therapeutic target for patients with colorectal cancer.

Additional file 1: Figure S1. The PDCD6 expression in different patient samples from the GEPIA database of different kinds of diseases. Figure S2a. PDCD6-KD and c-Raf-KD inhibited the MAPK pathway. Figure S2b. Combined downregulation of PDCD6 with oxiliplatin effect on cell proliferation in HCT116 and HCT15. Figure S2c. Cell proliferation assays on RAF709 and Trametinib treatment. Figure S2d. Colony formation assays on RAF709 and Trametinib treatment. Figure S3a. Representative immunohistochemistry images of the expression of p-c-Raf, p-MEK, c-Caspase 3 and p-Stat 3 in xenograft tumors from nude mice subcutaneously injected with HCT116 cells. *, P < 0.05. Figure S3b. HE staining showed the influences of PDCD6-KD and PDCD6-OE on mice tumor samples. Table S1. Characteristics of 93 patients with colorectal cancer included in the study. Table S2. For the knockdown of human PDCD6-specific shRNAs. Table S3. For the knockdown of human PDCD6-siRNA and c-Raf-siRNA. Table S4. Oligonucleotide sequences used in reverse-transcription PCR and real-time PCR.