Tumor hypoxia contributes to the development of resistance to chemotherapeutic drugs in several human cancer cell lines. Atovaquone, an anti‑malaria drug approved by the US Food and Drug Administration, has recently demonstrated anti‑cancer effects in vitro and in vivo in several cancer models. To assess the potential of atovaquone as an anti‑cancer agent under hypoxia in colorectal carcinoma, EpCAM⁺CD44⁺ colon cancer stem cells were isolated from HCT‑116 human colon cancer cells through magnetic‑activated cell sorting. The efficacy of atovaquone on cytotoxicity, tumorsphere formation, apoptosis, invasion and cell‑cycle progression under hypoxic conditions were evaluated. MTS assays indicated that atovaquone inhibited the proliferation of EpCAM⁺CD44⁺ HCT‑116 cells with a half‑maximal inhibitory concentration of 15 µM. Atovaquone inhibited tumorsphere formation and cell proliferation by causing cell‑cycle arrest in S‑phase, which induced apoptosis of EpCAM⁺CD44⁺ HCT‑116 cells, as detected by Annexin V‑FITC/PI double staining assays, and caused mitochondrial membrane potential depolarization, as determined by a JC‑1 staining assay. Reverse transcription‑quantitative PCR demonstrated increased expression of Bax and downregulation of Bcl‑2. Transwell invasion assays indicated that atovaquone inhibited the invasiveness of EpCAM⁺CD44⁺ HCT‑116 cells under hypoxia, which was associated with upregulation of MMP‑2 and ‑9 and increased expression of tissue inhibitor of MMPs (TIMP)‑1. Taken together, atovaquone reduced the tumorsphere formation and invasion ability of EpCAM⁺CD44⁺ HCT‑116 cells, at least in part by increasing the expression of TIMP‑1 and downregulating the expression of MMP‑2 and ‑9, as well as the cells' viability by inducing cell‑cycle arrest in S‑phase and induction of apoptosis via the Bcl‑2/Bax pathway under hypoxic conditions. Further studies are warranted to explore the mechanisms of action of atovaquone as a promising anticancer agent in the treatment of colorectal carcinoma.

This study explored the role of lymphocyte antigen 6 family member D (LY6D) in colon cancer stem cells’ (CCSCs) proliferation and invasion. LY6D was knocked down using siRNA, and the down-regulation of LY6D was verified using Western blotting. After LY6D knockdown, CCSCs’ proliferation, stemness, and invasion were suppressed, whereas apoptosis was increased. Gene Ontology (GO) enrichment analysis revealed that the differentially expressed genes (DEGs) between siLY6D and the negative control groups were significantly enriched in the cell–substrate adherens junction, focal adhesion, and cell–substrate junction terms. Meanwhile, the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that the DEGs were significantly enriched in the MAPK pathway. In addition, Western blotting results showed that pBRAF and pERK1/2, cascade kinases of the MAPK pathway, were significantly down-regulated after LY6D knockdown. In addition, nude mice xenograft experiments showed that the siLY6D treatment decreased tumor sizes and weights and improved tumor-bearing mice survival rates compared with the control group. In conclusion, these findings indicate that LY6D, which is highly expressed in CCSCs, is a key factor involved in tumor growth and development and might be a potential cancer marker and therapeutic target for colon cancer.

BACKGROUND: Epidemiological and mechanistic data support a potential causal link between cardiovascular disease (CVD) and cancer. Abdominal aortic aneurysms (AAAs) represent a common form of CVD with at least partially distinct genetic and biologic pathogenesis from other forms of CVD. The risk of cancer and how this risk differs compared with other forms of CVD, is unknown among AAA patients. We conducted a retrospective cohort study using the IBM MarketScan Research Database to test whether individuals with AAA have a higher cancer risk independent of traditional shared risk factors. METHODS: All individuals ≥18 years of age with ≥36 months of continuous coverage between 2008 and 2020 were enrolled. Those with potential Mendelian etiologies of AAA, aortic aneurysm with nonspecific anatomic location, or a cancer diagnosis before the start of follow-up were excluded. A subgroup analysis was performed of individuals having the Health Risk Assessment records including tobacco use and body mass index. The following groups of individuals were compared: (1) with AAA, (2) with non-AAA CVD, and (3) without any CVD. RESULTS: The propensity score–matched cohort included 58 993 individuals with AAA, 117 986 with non-AAA CVD, and 58 993 without CVD. The 5-year cumulative incidence of cancer was 13.1% (12.8%–13.5%) in participants with AAA, 10.1% (9.9%–10.3%) in participants with non-AAA CVD, and 9.6% (9.3%–9.9%) in participants without CVD. Multivariable-adjusted Cox proportional hazards regression models found that patients with AAA exhibited a higher cancer risk than either those with non-AAA CVD (hazard ratio, 1.28 [95% CI, 1.23–1.32]; P <0.001) or those without CVD (hazard ratio, 1.32 [95% CI, 1.26–1.38]; P <0.001). Results remained consistent after excluding common smoking-related cancers and when adjusting for tobacco use and body mass index. CONCLUSIONS: Patients with AAA may have a unique risk of cancer requiring further mechanistic study and investigation of the role of enhanced cancer screening.

Stimulating efferocytosis, the phagocytic removal of apoptotic cells by macrophages, has been proposed as a method to eliminate dying or dead cells that accumulate and contribute to diseases such as cancer, atherosclerosis, and infection. Toxicity related to the off-target clearance of healthy tissue has led to the premature termination of multiple clinical programs for proefferocytic therapies. To identify potential proefferocytic therapies with established risk profiles, we screened ~3000 US Food and Drug Administration (FDA)–approved drugs and other well-characterized compounds for their capacity to stimulate efferocytosis. We found that the antipsychotic drug thiothixene stimulated efferocytosis of apoptotic and lipid-laden cells by mouse and human macrophages and enhanced the continual efferocytosis of apoptotic cells. Consistent with thiothixene’s suppressive effects on dopaminergic signaling, dopamine potently inhibited efferocytosis in a manner that was only partially reversed by thiothixene. The prophagocytic effects of thiothixene in mouse macrophages depended on increased expression of the gene encoding the retinol-binding protein receptor Stra6L, which, in turn, promoted the production of the continual efferocytosis stimulator arginase 1. Our findings demonstrate that dopamine inhibits efferocytosis in macrophages and identify thiothixene, a generic, FDA-approved antipsychotic drug that has been in use for more than 50 years, as a promising candidate for promoting continual efferocytosis and the removal of diseased tissue.

Lymphocyte antigen 6 complex, locus K (LY6K) is a putative oncogene in various human cancers, including colorectal cancer, where elevated expression is associated with poor prognosis. This study investigates the antitumor effects of LY6K in colon cancer stem cells (CCSCs) both in vitro and in vivo. EpCAM and CD44 surface markers were used to isolate CCSCs from HCT116 cells, and the expression of LY6K in CCSCs was analyzed by real-time PCR. RNA interference was used to silence LY6K to evaluate its potential role of LY6K on the proliferation, migration, invasion, and cell cycle of CCSCs. Functional assays, including MTS assays, flow cytometric analyses, Transwell migration and invasion assays, and a xenograft model, were used for analysis. The results revealed that LY6K was highly expressed in CCSCs. siRNA-mediated LY6K-silencing in CCSCs inhibited cell proliferation by inducing G1 phase cell cycle arrest and suppressed migration and invasion. In vivo, LY6K silencing effectively reduced tumor growth and extended survival in a mouse model. These findings suggest LY6K as a promising therapeutic target for eradicating CCSCs in colorectal cancer treatment.

Prostate stem cell antigen (PSCA), a pivotal member of the lymphocyte antigen-6 (Ly6) protein family, has been implicated in the tumorigenesis and neoplastic progression of diverse cancer types. In this study, we conducted a thorough investigation into the role of PSCA in the development of colorectal cancer (CRC). Survival analysis based on The Cancer Genome Atlas (TCGA) dataset demonstrated that elevated expression of PSCA was tightly correlated with unfavorable overall survival, inferior relapse-free survival, and worse post-progression survival among CRC patients. Additionally, PSCA exhibited significantly higher expression levels in colorectal cancer stem cell (CRC-SCs) relative to CRC cell lines. Loss-of-function assays using small interfering RNA (siRNA)-mediated silencing were performed to evaluate the effects of PSCA downregulation on the stemness properties of CRC-SCs, including proliferative capacity, invasive potential, and apoptotic rate, which were assessed by MTS assay, transwell invasion assay, and flow cytometry analysis, respectively. The results showed that silencing PSCA markedly suppressed the proliferation and invasion of CRC-SCs, while significantly promoting cellular apoptosis. RNA sequencing was performed to identify differentially expressed genes (DEGs) in the PSCA knockdown group compared to the negative control group. Follow-up analyses using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) indicated that these DEGs were significantly enriched in the cell-substrate adherens junction term and the mitogen-activated protein kinase 9MAPK signaling pathway. Moreover, PSCA silencing substantially reduced the phosphorylation levels of the core MAPK signaling constituents, pBRAF and pERK1/2; conversely, PSCA overexpression prominently upregulated the expression of pBRAF and pERK1/2. In nude mice with CRC-SCs cancer xenograft tumors, treatment with PSCA siRNA significantly decreased tumor volume and weight, while also notably extending the survival time of the tumor-bearing mice compared to the control group. Collectively, these findings confirm that PSCA plays a critical oncogenic role in CRC cancer growth and malignant progression, suggesting its potential as a novel and promising therapeutic target for CRC.