The novel protein C9orf116 promotes rat liver cell line BRL-3A proliferation

Impaired AKT signaling and lung tumorigenesis by PIERCE1 ablation in KRAS-mutant non-small cell lung cancer

KRAS-mutant non-small cell lung cancer (NSCLC) is a major lung cancer subtype that leads to many cancer-related deaths worldwide. Although numerous studies on KRAS-mutant type NSCLC have been conducted, new oncogenic or tumor suppressive genes need to be detected because a large proportion of NSCLC patients does not respond to currently used therapeutics. Here, we show the tumor-promoting function of a cell cycle-related protein, PIERCE1, in KRAS-mutant NSCLC. Mechanistically, PIERCE1 depletion inhibits cell growth and AKT phosphorylation (pAKT) at S473, which is particularly observed in KRAS-mutant lung cancers. Analyses of AKT-related genes using microarray, immunoblotting, and real-time quantitative PCR indicated that PIERCE1 negatively regulates the gene expression of the AKT suppressor, TRIB3, through the CHOP pathway, which is a key regulatory pathway for TRIB3 expression. Similarly, in vivo analyses of PIERCE1 depletion in the KRAS mutation-related lung cancer mouse models revealed the suppressive effect of PIERCE1 knockout in urethane- and KRAS^G12D-induced lung tumorigenesis with decreased pAKT levels observed in the tumors. Tissue microarrays of human lung cancers indicated the expression of PIERCE1 in 83% of lung cancers and its correlation with pAKT expression. Thus, we illustrate how PIERCE1 depletion may serve as a therapeutic strategy against KRAS-mutant NSCLC and propose the clinical benefit of PIERCE1.

Effect of PIERCE1 on colorectal cancer

Colorectal cancer is the second most lethal cancer type across all ages and sexes, the many mechanisms of which are still currently being further elucidated. PIERCE1 has been known to be involved in the cell cycle and proliferation, the expression of which is regulated by stress conditions in a p53-dependent manner. Through a database search, we found that PIERCE1 was significantly augmented in patients with colorectal carcinoma compared to normal samples, suggesting its possible role in tumor regulation. Recently, PIERCE1 has also been reported to increase proliferation of a liver cancer cell line, indicating its possible role as an oncogene. To examine its relevance to tumorigenesis, such as whether it has either oncogenic or tumor suppressive function, PIERCE1 was knocked down and overexpressed in several colorectal cancer cell lines and mice, respectively. To evaluate the roles of Pierce1 in vivo, we established a Pierce1 transgenic (TG) mouse model and then administered azoxymethane with dextran sodium sulfate (DSS) to induce colorectal carcinogenesis via promoting mutations in Apc and Kras. Nonetheless, PIERCE1 depletion in these cell lines showed no significant change in cell growth. AOM/DSS-treated Pierce1 TG mice were comparable with respect to colon lengths, the number of polyps, and tumor sizes to those of the control mice. These results implicate that PIERCE1 does not play an oncogenic or tumor suppressive role in AOM/DSS-induced colorectal cancer.