Cancer stem cells (CSCs) are a small proportion of tumor cells that may be responsible for tumor metastasis and recurrence. Our recent research indicated that longikaurin A (LK-A) exhibited anti-tumor activity in nasopharyngeal carcinoma (NPC) both in vitro and in vivo. Here, we further investigated whether LK-A could suppress the stemness of NPC cells. Sphere formation assay was used to assess the self-renewal ability of the cells treated with LK-A. Side population (SP) was determined by flow cytometry to measure the influence of LK-A on NPC SPs. The expression of the c-myc and fibronectin was detected by western blotting. The cytotoxicity of LK-A in combination with cisplatin to NPC cells was determined by MTT assay. Colony formation assay was used to verify whether LK-A could sensitize NPC cells to radiation and reverse the radiotherapy resistance. In the present study, we found that LK-A reduced the number and size of spheroid formation and decreased the SP cell percentage of the S18 cell line at a low concentration. Furthermore, LK-A treatment downregulated the expression of c-myc and fibronectin in NPC cell lines. Moreover, LK-A could significantly enhance the chemotherapeutic and radiotherapeutic sensitivity of NPC cell lines and reverse acquired radiotherapy resistance of Sune2-IR. Our data revealed that LK-A could suppress the stemness of NPC cells and may enhance the efficacy of radiotherapy and chemotherapy.

The majority of neuroendocrine tumors appear to be sporadic. Neuroendocrine carcinoma (NEC) typically arises in pancreatic, parathyroid and adrenal glands, but rarely arises in salivary glands. NEC of the tonsil is a rare type of tumor and the concurrent presentation of hepatocellular carcinoma (HCC) is considered to be more uncommon. There are few case reports of NEC of the tonsil in the literature and to date no studies have been conducted to establish its optimal management. The current study presents a case of a 72‑year‑old male who presented with left neck and tonsil tumors. A biopsy from the tonsil revealed a NEC, and computed tomography showed liver cirrhosis, multiple liver cancers and portal vein thrombosis, as well as metastasis to the hilar, abdomen and retroperitoneum. Histological examination of the hepatic revealed primary HCC. To the best of our knowledge, this is a condition that has not previously been reported.