Spontaneous basal cell carcinoma in a 7-week-old Sprague-Dawley rat

A 13-Week Repeated Oral Dose Toxicity Study of ChondroT in Sprague-Dawley Rats

Background

ChondroT, a new herbal medication, consists of Angelica grosseserrata Maxim., Lonicera japonica Thunb., Angelica gigas Nakai, Clematis terniflora var. manshurica (Rupr.) Ohwi, and Phellodendron amurense Rupr. (6:4:4:4:3). Our previous studies have shown that ChondroT exhibits significant anti-arthritic and anti-inflammatory effects. In this study, we aimed to assess the toxicological safety assessment of ChondroT.

Methods

This study was designed to assess the safety of ChondroT after repeated oral administration.

Male and female Sprague-Dawley rats were treated with ChondroT at oral doses of 0, 500, 1000, and 2000 mg/kg for 13 weeks. Mortality, clinical signs, body weight changes, food consumption, ophthalmological findings, urinalysis, hematological and blood-chemical parameters, necropsy findings, organ weights, and histological markers were recorded throughout the study period. Rats were also monitored for an additional 4 weeks to determine the recovery time.

Results

No death occurred and no significant changes in food consumption, ophthalmologic findings, and urinalysis were found. Although there were alterations in clinical signs, body weights, hematological parameters, blood-chemical parameters, necropsy findings, organ weights, and histological markers, they were not considered to be toxicologically significant.

Conclusions

The results suggest that the no-observed adverse effects level (NOAEL) was 2000 mg/kg/day for the test substance. ChondroT, a new complex herbal medication composed of five plants, can therefore be used safely at the NOAEL.

Establishment of basal cell carcinoma animal model in Chinese tree shrew (Tupaia belangeri chinensis)

Basal cell carcinoma (BCC) is the most common skin cancer worldwide, with incidence rates continuing to increase. Ultraviolet radiation is the major environmental risk factor and dysregulation of the Hedgehog (Hh) signaling pathway has been identified in most BCCs. The treatment of locally advanced and metastatic BBCs is still a challenge and requires a better animal model than the widely used rodents for drug development and testing. Chinese tree shrews (Tupaia belangeri chinensis) are closely related to primates, bearing many physiological and biochemical advantages over rodents for characterizing human diseases. Here, we successfully established a Chinese tree shrew BCC model by infecting tail skins with lentiviral SmoA1, an active form of Smoothened (Smo) used to constitutively activate the Hh signaling pathway. The pathological characteristics were verified by immunohistochemical analysis. Interestingly, BCC progress was greatly enhanced by the combined usage of lentiviral SmoA1 and shRNA targeting Chinese tree shrew p53. This work provides a useful animal model for further BCC studies and future drug discoveries.

A spontaneous basal cell carcinoma with pulmonary metastasis in a 6-week-old SD rat

To our knowledge, this is the first report on basal cell carcinoma with lung metastasis in a rat. A 6-week-old male Sprague-Dawley rat presented ulceration of the oral mucosa with surrounding tumor growth and white nodules in the lung. Microscopically, the mass showed solid, sheet-like growth with a partially lobular pattern and invaded the gingival mucosa, maxilla, and nasal submucosa. The nuclei of tumor cells were round to oval in shape with basophilic cytoplasm and a large number of mitotic figures. The pulmonary nodules were almost identical to the maxillary tumor in histopathological characteristics. Immunohistochemically, tumor cells were positive for cytokeratin, vimentin, PCNA, and p63 and negative for desmin, S-100, and αSMA. Based on these results, we diagnosed the tumor as a maxillary basal cell carcinoma with pulmonary metastasis.

Spontaneously occurring multicentric basal cell carcinoma and keratoacanthomas in a multimammate mouse (Mastomys spp.)

A multicentric basal cell carcinoma was diagnosed in a male multimammate mouse (Mastomys spp.) with widespread cutaneous alterations. Macroscopically, the skin was thickened and extremely wrinkled. Histopathological examination showed multicentric expanding cell-rich tumors composed of basaloid cells interpreted as basal cell carcinoma. Immunohistochemistry detected strong cytokeratin 14 positivity in the epidermal basal layer and in loosely arranged areas of these tumors but only a minimal positive reaction in densely packed areas of tumor cells. Furthermore, samples from the abdomen showed 3 nodular proliferations diagnosed as keratoacanthomas.