Su Huang

AIM: To explore relationships between human carcinomas and mycoplasma infection. METHODS: Monoclonal antibody PD4, which specifically recognizes a distinct protein from mycoplasma hyorhinis, was used to detect mycoplasma infection in different paraffin embedded carcinoma tissues with immunohistochemistry. PCR was applied to amplify the mycoplasma DNA from the positive samples for confirming immunohistochemistry. RESULTS: Fifty of 90 cases (56%) of gastric carcinoma were positive for mycoplasma hyorhinis. In other gastric diseases, the mycoplasma infection ratio was 28% (18/49) in chronic superficial gastritis, 30% (14/46) in gastric ulcer and 37% (18/49) in intestinal metaplasia. The difference is significant with gastric cancer (chi(2) = 12.06, P < 0.05). In colon carcinoma, the mycoplasma infection ratio was 55.1% (32/58),but it was 20.9% (10/49)in adenomarous polyp (chi(2)=13.46, P < 0.005). Gastric and colon cancers with high differentiation had a higher mycoplasma infection ratio than those with low differentiation (P < 0.05). Mycoplasma infection in esophageal cancer, lung cancer, breast cancer and glioma was 50.9% (27/53), 52.6% (31/59), 39.7% (25/63) and 41% (38/91), respectively. The mycoplasma DNA was successfully amplified with the DNA extracted from the cancer tissues that were positive for mycoplasma infection (detected with antibody PD4). CONCLUSION: There was high correlation between mycoplasma infection and different cancers, which suggests the possibility of an association between the two. The mechanism involved in oncogenesis by mycoplasma remains unknown.

Immunostaining using an affinity-purified rabbit polyclonal antibody against the extracellular domain of the epidermal-growth-factor receptor (EGFR) showed over-expression occurring in a fraction of tumor cells in 17 out of 18 human glioblastomas and in a majority of cells in 7 of the 18. Southern-blotting technique using a full-length EGFR cDNA probe showed a variable degree of amplification in 10 of the 17 glioblastomas, which was associated with EGFR over-expression in each case. In 2 of the glioblastomas with EGFR gene amplification, a rearrangement of the gene affecting the extracellular domain of the receptor was identified and DNA sequence analyses revealed an identical deletion-rearrangement of 801 base pairs between exons 2 to 7, resulting in an in-frame fusion of exons 1 and 8.

OBJECTIVE: To explore the association between the carcinoma and mycoplasma infection by immunohistochemistry. METHODS: Antigen of anti-tumor monoclonal antibody PD4 was identified as mycoplasma hyorhinis. Using immunohistochemistry to study archived paraffin-embedded gastriointestinal tract carcinomas tissue. The PCR was applied to amplify the mycoplasma DNA for confirming immunohistochemistry results. RESULTS: It was showed that mycoplasma was present in 56% (50/90 cases) of gastric carcinoma. The cancer tissues with high differentiation had a higher mycoplasma infection ratio than that of low differentiation cancer tissues. (P < 0.05). In control cases, mycoplasma infection was 28% (18/49) in chronic superficial gastritis, 30% (14/46) in gastric ulcer and 37% (18/49) in intestinal metaplasia of the stomach. Mycoplasma infection was 55.1% (32/58) in colon carcinoma and 20.9% (10/49) in adenomarous polyp (P < 0.005). It seems that colon carcinoma tissues with slight pathological grade had a higher percent of mycoplasma infection than that of cancer tissues with moderate and heavy pathological grade (P < 0.05). CONCLUSION: The high infection of mycoplasmas in carcinoma tissues suggest an association between mycoplasma and cancer. The mechanism involved in oncogenesis by mycoplasmas remains to be elucidated.