Dclk1 Inhibition Cancels 5-FU-induced Cell-cycle Arrest and Decreases Cell Survival in Colorectal Cancer

Abstract

is frequently used in colorectal cancer treatment, but with limited success. The aim of the present study was to explore the cytotoxic effects of 5-FU, in combination with inhibition of doublecortin-like kinase 1 (Dclk1), a tumor stem cell marker that regulates pro-survival signaling in colorectal cancer cells, in the human colon cancer cell line, The effects of 5-FU treatment plus Dclk1 inhibition on the phosphorylation of checkpoint kinase 1 (Chk1), cell cycle, DNA damage, apoptosis, and cell survival in COLO-320 cells were evaluated. Results: Combined treatment with 5-FU and a Dclk1 inhibitor, LRRK2-IN-1 (LRRK), decreased 5-FU-induced phosphorylation of Chk1 and canceled 5-FU-induced cell-cycle arrest at the S phase. Combined treatment with 5-FU and LRRK failed to induce poly (ADP-ribose) polymerase 1 (PARP-1) cleavage, but tended to decrease cell survival compared to individual treatment with 5-FU or LRRK. Conclusion: These results indicate that a combination of 5-FU and LRRK may be an effective, novel approach for colorectal cancer therapy.Colorectal cancer is the third leading cause of cancer-related death in the world and represents a severe threat to human health (1). 5-Fluorouracil (5-FU), a pyrimidine analogue, induces the inhibition of DNA synthesis through inhibition of thymidylate synthetase and is misincorporated into DNA and RNA, leading to the induction of cell-cycle arrest at G 1 /S phase (2). Presently, the combination of infused 5-FU/leucovorin (LV) plus irinotecan or oxaliplatin, known as the FOLFIRI (3) and FOLFOX4 regimens (4), represents the standard first-line chemotherapy. However, the emergence of tumor cells with acquired pharmacological resistance to these agents limits the antitumor effect of these therapies. Tumor cell-acquired pharmacological resistance leads to development of metastasis, which is responsible for approximately 90% of colorectal cancer-related mortality (5).5-FU treatment induces the phosphorylation of checkpoint kinase 1 (Chk1), a cell-cycle checkpoint protein, and arrests cell-cycle progression at the S phase (6, 7). Thus, combined treatment with 5-FU and Chk1 inhibition is expected to increase cell death due to lethal chromosomal instability caused by the progression of the cell cycle without repairing the damaged DNA at the arrested S phase. Therefore, the combined effect of 5-FU and Chk1 inhibition has previously been examined. As expected, Chk1 inhibition sensitized the cells to 5-FU-induced cytotoxicity (6-8). Furthermore, this combined treatment is found to increase cell death in colorectal cancer cells compared to individual treatment with 5-FU or Chk1 inhibitor (9). However, Chk1 plays an important role in the cell-cycle checkpoint of normal cells, and therefore combined treatment with 5-FU and Chk1 inhibitor may lead to severe side-effects caused by cytotoxicity in normal cells. Therefore, it is necessary to identify a molecular target specifically in cancer cells to increase the cytotoxic effect of 5-FU without causing severe side-effects.Doublecortin-l...

Potent effects of dioscin against hepatocellular carcinoma through regulating TP53‐induced glycolysis and apoptosis regulator (TIGAR)‐mediated apoptosis, autophagy, and DNA damage

“…To evaluate the in vivo anticancer of dioscin, SMMC7721 and HepG2 cells tumour xenograft model were used and 5‐FU, which is a fluorinated pyrimidine analogue that acts as an antimetabolic agent, inhibiting thymidylate synthase and interfering with RNA synthesis and representing the standard first‐line chemotherapy to treat cancer (Suehiro et al, ), was applied as the positive drug. As shown in Figure a, the significant differences in tumour volumes were found based on tumour images after 27 days of treatment.…”

Identification of crucial genes and pathways associated with colorectal cancer by bioinformatics analysis

“…To further comprehend the biological effects of the DEGs identified and the pathways associated with CRC that they accumulate in, GO term and KEGG pathway enrichment analyses were performed. The results of the GO term functional analysis indicated that the DEGs identified were mainly involved in the following terms: 'Mitotic nuclear division', 'positive regulation of cell proliferation', 'one-carbon metabolic process', 'cell division', 'immune response', 'hormone (26)(27)(28). However, the underlying mechanisms through which the corresponding proteins in these signalling cascades promote tumorigenesis remain elusive.…”

Proteogenomic Landscape of Breast Cancer Tumorigenesis and Targeted Therapy

“…For example, phosphoproteomics identified new connections between tumor suppressor loss and signaling, including upregulation of RIPK3 in MAP3K1 mutant tumors, the WNT pathway mediator TNIK1 in ARID1A mutant tumors, and the microtubule-associated kinase and neuroendocrine differentiation markers MAST4 and DCLK1 (Liu et al, 2016) in GATA3 mutant tumors. The first two findings suggest potential therapeutic directions in the difficult arena of targeting tumor suppressor loss, whereas DCLK1 inhibition via the small-molecule kinase inhibitor LRRK2-IN-1 has shown preclinical efficacy in some cancers (Kawamura et al, 2017;Suehiro et al, 2018;Weygant et al, 2014). Proteomics and acetylproteomics profiling in the context of metabolism also revealed, for the first time in a large BRCA cohort, marked differences in metabolic enzyme expression and acetylation between luminally-and basally-enriched subtypes, which may translate to a better understanding of metabolic vulnerabilities.…”