The DDX6/KIFC1 signaling axis, as regulated by YY1, contributes to the malignant behavior of pancreatic cancer

Human DEAD/H box RNA helicase DDX6 acts as an oncogene in several different types of cancer, where it participates in RNA processing. Nevertheless, the role of DDX6 in pancreatic cancer (PC), together with the underlying mechanism, has yet to be fully elucidated. In the present study, compared with adjacent tissues, the level of DDX6 was abnormally increased in human PC tissues, and this increased level of expression was associated with poor prognosis. Furthermore, the role of DDX6 in PC was investigated by overexpressing or silencing the DDX6 in the PC cell lines, SW1990 and PaTu-8988t. A xenograft model was established by injecting nude mice with either DDX6-overexpressing or DDX6-silenced SW1990 cells. DDX6 overexpression promoted the proliferation and cell cycle transition, inhibited the cell apoptosis of PC cells, and accelerated tumor formation, whereas DDX6 knockdown elicited the opposite effects. DDX6 exerted positive effects on PC. RNA immunoprecipitation assay showed that DDX6 bound to kinesin family member C1 (KIFC1) mRNA, which was further confirmed by RNA pull-down assay. These results suggested that DDX6 positively regulated the expression of KIFC1. KIFC1 overexpression enhanced the proliferative capability of PC cells with DDX6 knockdown and inhibited their apoptosis. By contrast, DDX6 overexpression reversed the inhibitory effect of KIFC1 silencing on tumor proliferation. Subsequently, the transcription factor Yin Yang 1 (YY1) was shown to negatively regulate DDX6 at both the mRNA and protein levels. Dual-luciferase reporter assay verified that YY1 targeted the promoter of DDX6 and inhibited its transcription. High expression levels of YY1 decreased the proliferation of PC cells and promoted cell apoptosis, although these effects were reversed by DDX6 overexpression. Taken together, YY1 may target the DDX6/KIFC1 axis, thereby negatively regulating its expression, leading to an inhibitory effect on pancreatic tumor.

Kinesin Family Member C1 (KIFC1/HSET) Underlies Aggressive Disease in Androgen Receptor-Low and Basal-Like Triple-Negative Breast Cancers

Quadruple-negative breast cancer (QNBC) lacks traditional actionable targets, including androgen receptor (AR). QNBC disproportionately afflicts and impacts patients of African genetic ancestry. Kinesin family member C1 (KIFC1/HSET), a centrosome clustering protein that prevents cancer cells from undergoing centrosome-amplification-induced apoptosis, has been reported to be upregulated in TNBCs and African-American (AA) TNBCs. Herein, we analyzed KIFC1 RNA levels and their associations with clinical features and outcomes among AR-low and AR-high TNBC tumors in three distinct publicly available gene expression datasets and in the breast cancer gene expression database (bc-GenExMiner). KIFC1 levels were significantly higher in AR-low and basal-like TNBCs than in AR-high and non-basal-like TNBCs, irrespective of the stage, grade, tumor size, and lymph node status. KIFC1 levels were also upregulated in AR-low tumors relative to AR-high tumors among Black and premenopausal women with TNBC. High KIFC1 levels conferred significantly shorter overall survival, disease-free survival, and distant metastasis-free survival among AR-low and basal-like TNBC patients in Kaplan-Meier analyses. In conclusion, KIFC1 levels may be upregulated in AR-low tumors and, specifically, in those of African descent, wherein it may promote poor outcomes. KIFC1 may be an actionable cancer-cell-specific target for the AR-low TNBC subpopulation and could aid in alleviating racial disparities in TNBC outcomes.

KIFC1 promotes the proliferation of hepatocellular carcinoma in vitro and in vivo

Hepatocellular carcinoma (HCC) is a common type of malignant tumor worldwide with a high mortality rate. In the past 20 years, the morbidity rate of HCC has increased. Progress has been made in the clinical diagnosis and therapy for HCC. However, due to the high heterogeneity and metastasis targeted therapy for HCC exhibits great promise, and novel therapeutic targets for HCC are urgently required. Kinesin family member C1 (KIFC1) is a member of the kinesin superfamily of proteins. Previous studies have indicated a potential association between KIFC1 and cancer progression. However, the potential role of KIFC1 in the development of HCC remains unclear. The present study aimed to explore the function of KIFC1 in HCC. Immunohistochemical (IHC) assays were performed to explore the KIF15 expression levels in 74 samples of HCC and corresponding non-tumor tissues. The potential association between KIF15 expression levels and clinical features was analyzed, and the effects of KIF15 on cell proliferation of HCC were detected by colony formation and MTT assays. In addition, the proliferation-related proteins Ki67 and PCNA were detected by western blotting. The possible effects of KIF15 on tumor growth were measured in mice. The results demonstrated that a high expression level of KIFC1 was associated with poor prognosis of HCC. Further results indicated that KIFC1 promoted cell proliferation of HCC in vitro. In addition, knockdown of KIFC1 suppressed tumor formation and growth in mice. Therefore, these results provide a potential therapeutic target for the treatment of HCC.

miR-135a acts as a tumor suppressor in gastric cancer in part by targeting KIFC1

miR-135a was downregulated in the majority of human primary gastric cancer (GC) tissues and GC cell lines. Kinesin family member C1 (KIFC1) was significantly upregulated in GC tissues and cell lines and promoted GC development and progression. We searched for miR-135a targets by using MiRanda, TargetScan, and PicTar tools, and found that KIFC1 was a potential target of miR-135a. Based on these findings, we speculated that miR-135a might target KIFC1 to inhibit GC growth. We determined the expression of miR-135a and KIFC1 by quantitative real-time polymerase chain reaction and Western blot assays, respectively, and found downregulation of miR-135a and upregulation of KIFC1 in GC tissues and cell lines. Cell proliferation and apoptosis assays showed that knockdown of KIFC1 inhibited proliferation and promoted apoptosis of GC cells, and miR-135a mimics had similar effects on GC cell proliferation and apoptosis. Furthermore, we verified that KIFC1 was a direct target of miR-135a, which confirmed our speculation that the functional effect of miR-135a on GC cells, at least, in part, depends on KIFC1. These findings suggest that miR-135a has an important role in the suppression of GC and presents a novel mechanism of miRNA-mediated KIFC1 expression in cancer cells.