Chronic cadmium exposure promotes nasopharyngeal carcinoma
Chronic cadmium exposure promotes nasopharyngeal carcinoma progression and radioresistance
Dr Lin Peng and her team investigate how environmental pollutant exposure influences the risk of cancer development and therapeutic resistance at the Department of Laboratory Medicine, Cancer Hospital of Shantou University Medical College, China.
Dr Lin Peng, Associate Chief Physician, works in the Department of Laboratory Medicine, Cancer Hospital of Shantou University Medical College, China. The research she led has focused on environmental pollutant exposure and the risk of cancer development and therapeutic resistance. Her team has recently published research results highlighting the association between cadmium and breast cancer, connecting gastrointestinal cancer risk to cadmium and lead exposure, association of polychlorinatedbiphenyls/polybrominated diphenyl ethers and breast cancer risk.
Nasopharyngeal carcinoma (NPC) is a unique malignancy with a high prevalence in East and Southeast Asia, especially in southern China. The unique ethnic and geographical distribution of NPC indicates hereditary factor and environmental factors may contribute to its unusual etiology. But to date, only nitrosamine, polycyclic aromatic hydrocarbons and nickel are regarded as environmental risk factors in the development and progression of NPC. Cadmium is a ubiquitous carcinogenic pollutant related to some human cancers. The aim of the present study was to evaluate the association between chronic low-concentration cadmium exposure and NPC progression and radiosensitivity.
Hospital-based 134 NPC cases and 132 cancer-free controls were recruited, the blood cadmium levels of whom were detected by graphite furnace atomizer absorption spectrophotometer and the basic clinical data and demographic characteristics were collected. To further confirm the effect of cadmium on NPC progression and radiosensitivity in vitro and in vivo, NPC cell lines CNE-1 and CNE-2 were continuously exposed with 1 μM cadmium chloride for 10 weeks. MTT assay, colony formation assay and xenograft tumour growth were used to assess cell viability and radiosensitivity. Transwell assays were performed to detect cell invasion and migration. The median concentration of blood cadmium in cases (3.84, IQR 2.21–6.10) was found significantly higher than that of controls (2.28, IQR 1.79–3.45)(P less than 0.001). Meanwhile, blood cadmium levels were positively associated with clinical stages and N classification (r=0.193, 0.187, respectively, Pless than 0.05).MTT assay and colony formation assays showed that the cell proliferation in cadmium exposed NPC cells was significantly increased compared to the parental cells(P less than 0.05). Also, the invasive and migrative capacity of cadmium-treated NPC cells was markedly increased over 1.40-(P less than 0.01) and 1.30-(P less than 0.01) fold of the controls, respectively. In particular, xenograft tumours with cadmium-treated NPC cells exhibited increased tumour growth and radioresistance compared to transplanted controls(P less than 0.05). These results reveal the stimulative effect of chronic low-dose cadmium exposure on malignant progression and radioresistance of NPC for the first time.
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