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The purpose of this study was to examine the effect of amygdalin on cell growth and telomerase activity in human cancer and MRC-5 fibroblast cell lines. The level of β-glucosidase activity for releasing cyanide was significantly (P < .05) higher in cancer cell lines (A-549, MDA-MB-231, MCF-7 and U87-MG) than in MRC-5 fibroblasts. Growth rate of cancer cells was apparently inhibited in concentrations above 10 mg/ml amygdalin with senescent-like abnormal morphology. Whereas the effects were absent or marginally detected in MRC-5 fibroblasts. High incidence of β-galactosidase activity was observed in amygdalin-treated cancer cells, compared with that of untreated control while no difference was observed between the control and amygdalin-treated MRC-5 fibroblasts. Furthermore, level of telomerase activity was significantly (P < .05) higher (∼8-13 fold) in cancer cell lines along with high expression of telomerase reverse transcriptase (TERT) and telomerase RNA component (TERC) than in MRC-5 fibroblasts which did not expressed TERT and TERC. However, telomerase activity was significantly (P < .05) down-regulated in amygdalin-treated cancer cells with the decreased expression of TERT and TERC compared with control cancer cells. There were no difference in the telomerase activity between control and amygdalin-treated MRC-5 fibroblasts. Based on these observations, we concluded that amygdalin treatment offers a valuable option for the cancer treatment, causing inhibition of cell growth and down-regulation of telomerase activity in human cancer cell lines by increasing β-glucosidase activity.

The present study assessed the cytotoxicity of sodium meta-arsenite (SMA) on telomere shortening and cellular apoptosis in human A-549, MDA-MB-231 and U87-MG cancer cell lines. Following 2 weeks of 1 μM SMA treatment, population doubling time (PDT) was significantly (P < .05) increased by the inhibition of cell proliferation in all the cancer cell lines compared to that in untreated controls. Level of telomerase activity by relative-quantitative telomerase repeat amplification protocol was significantly (P < .05) downregulated by SMA treatment with significant (P < .05) decrease of both telomerase reverse transcriptase and telomerase RNA component transcripts, responsible for telomerase activity. A significant (P < .05) shortening of telomeric repeats by telomere restriction fragment analysis was consequently observed in SMA-treated cells. Moreover, high incidence of cells with senescence-associated β-glucosidase activity was observed in SMA-treated cells and some cells were also differentiated into adipocytes probably due to the loss of tumorous characterizations. Cellular apoptosis proven by DNA fragmentation was observed, and intrinsic apoptotic transcripts (BAX, caspase 3 and caspase 9) and stress-related transcripts (p21, HSP70 and HSP90) were significantly (P < .05) increased in three cancer cell lines treated with SMA. Based on the present study, SMA treatment apparently induced a shortening of telomere length and cytotoxicity, such as induction of cell senescence, apoptosis and cell differentiation. Therefore, we conclude that SMA treatment at specific concentration can lead to gradual loss of tumorous characterizations and can be considered as a potential anti-cancer drug for chemotherapy treatment.

A 20‐year‐old Korean woman presented in August 1999 with a 3‐month history of multiple, tiny papules on the periorbital and malar areas (Fig. 1a). She had noted hyperhidrosis for the preceding 6 months, even at room temperature. She had been well and had received no medication prior to her first visit to our clinic. Physical examination showed yellow colored, translucent, small papules, as well as finger tremor, exophthalmos, and a goiter. Histologic examination demonstrated cystic structures in the dermis lined with two layers of cuboidal epithelial cells (Fig. 2). The epidermis was normal and the rete ridges were partially effaced. Immunohistochemical studies revealed that the epithelial cells of the cyst wall were carcinoembryonic antigen (CEA) positive but S‐100 protein negative. 1 Multiple tiny papules on the periorbital and malar areas before (a) and after (b) treatment for Graves’ disease 2 Staining with hematoxylin and eosin (× 100); (b) Staining with hematoxylin and eosin (× 200); (c) CEA‐positive epithelial cells; (d) S‐100 protein‐negative epithelial cells Because a goiter and finger tremor were noted on physical examination, hyperthyroidism was suspected. Thyroid function test results were: triiodothyronine (T3), 8.0 ng/mL (normal range, 0.7–1.9 ng/mL); free thyroxine (T4), 8.1 ng/mL (0.7–1.9 ng/mL); T4, 35 µg/dL (6.0–11.8 µg/dL); thyroid‐stimulating hormone (TSH), 0.04 IU/mL (0.25–4.0 IU/mL); positive for anti‐TSH receptor antibody. On the basis of these findings, the patient was diagnosed with Graves’ disease and treated with methimazole, 40 mg/day. As the patient's symptoms improved, the therapeutic dose was decreased to 20 mg/day. Four months after the beginning of treatment, the free T4 and T3 values had returned to the normal range (Table 1). The skin lesions, finger tremor, and hyperhidrosis had also disappeared. Exophthalmos was improved, but still present (Fig. 1b). Comparison of thyroid hormone values in Graves’ disease pretreatment and post‐treatment T3 (ng/mL) Free T4 (ng/mL) Pretreatment8.08.1Post‐treatment1.00.15 T3, triiodothyronine; T4, thyroxine.

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