Construction and screening of suppression subtractive hybridization library of renal cell carcinoma

Objective To construct and screen the suppression subtractive hybridization (SSH) library of human renal cell carcinoma (RCC). Methods Poly A+ RNA was isolated from RCC lines 786-O(tester) and renal cell(RC) lines HK-2 ( driver), respectiely. SSH procedure was performed according to the protocol of the PCR-Select cDNA Subtraction Kit ( Clontech), and PCR products were cloned into pT-Adv vector and transformed E. coli TOP10F’. All positive clones picked out were digested and some of which were sequenced. Results The SSH library contained 362 clones with SSH cDNA fragments distributed mainly from 0.3 to 0.9 kb. Among 50 clones sequenced randomly,2 represented unknown genes and the other 48 derived from 36 known genes. Conclusion The quality of the SSH library of human RCC is reliable and is construction is the basis for further screening differentially expressed genes of RCC. 6 refs,4 figs, 1 tab.

Relationship between trefoil factor 1 expression and gastric mucosa injuries and gastric cancer

AIM:To determine whether trefoil factor 1 (TFF1) is associated with mucosa healing and carcinoma suppression, we assess the expression of trefoil factor 1 in normal and pathologic gastric mucosa. METHODS: TFF1 in normal and pathologic gastric mucosa was assessed by immunohistochemical method, and the average positive A was estimated by Motic Images Advanced 3.0 software. RESULTS: Increased TFF1 was detected in gastritis, gastric ulcer and duodenal ulcer compared with normal mucosa. The same result could be seen in multiple and compound ulcer compared with simple ulcer. There was no significant difference between gastric ulcer and duodenal ulcer, gastritis and simple ulcer respectively. Increased TFF1 was detected in the peripheral mucosa of the gastric adenocarcinoma compared with normal mucosa. The expression of TFF1 in gastric adenocarcinoma was related to the differentiation of adenocarcinoma. The lower the differentiation of adenocarcinoma, the weaker the expression of TFF1. There was no TFF1 expressed in low-differentiated adenocarcinoma. The expression of TFF1 in middle and highly differentiated adenocarcinoma was a little lower than that in normal mucosa. But there was no significant difference. No TFF1 was assessed in esophageal squamous carcinoma and peripheral tissue. There was no significant difference between male and female. CONCLUSION: The expression of TFF1 was higher in gastritis and peptic ulcer than that in normal mucosa, and was also higher in multiple and compound ulcer than in simple ulcer. It seems that TFF1 plays a role in gastric mucosa protection and epithelial restitution. Increased expression of TFF1 in peripheral tissue suggests that TFF1 is associated with mechanism of carcinoma suppression and differentiation. Decreased expression of TFF1 in carcinoma and its relativity to the differentiation suggests that TFF1 is related to gland and cell destruction of carcinoma.

Molecular forms of trefoil factor 1 in normal gastric mucosa and its expression in normal and abnormal gastric tissues

AIM： To study the molecular forms of trefoil factor 1 （TFF1） in normal gastric mucosa and its expression in normal and abnormal gastric tissues （gastric carcinoma, atypical hyperplasia and intestinalized gastric mucosa） and the role of TFF1 in the carcinogenesis and progression of gastric carcinoma and its molecular biological mechanism underlying gastric mucosa protection. METHODS： The molecular forms of TFF1 in normal gastric mucosa were observed by Western blot. The expression of TFF1 in normal and abnormal gastric tissues （gastric carcinoma, atypical hyperplasia and intestinalized gastric mucosa） was also assayed by immunohistochemical method. The average positive AO was estimated by Motic Images Advanced 3.0 software. RESULTS： Three patterns of TFF1 were found in normal gastric mucosa： monomer, dimmer, and TFF1 compound whose molecular weight is about 21 kDa. The concentration of TFF1 compound was the highest among these three patterns. TFF1 was expressed mainly in epithelial cytoplasm of the mucosa in gastric body and antrum, especially around the nuclei. The closer the TFF1 to the lumen, the higher the expression of TFF1, The expression of TFF1 in peripheral tissue of gastric carcinoma （0.51 ± 0.07） was higher than that in normal gastric mucosa （0.44 ± 0.06, P 〈 0.001）. The expression of TFF1 in gastric adenocarcinoma was positively related to the differentiation of adenocarcinoma. The lower the differentiation of adenocarcinoma was, the weaker the expression of TFF1. No TFF1 was expressed in poorlydifferentiated adenocarcinoma. The expression of TFF1 in moderately-well differentiated adenocarcinoma （0.45 ± 0.07） was a little lower than that in normal mucosa （P 〉 0.05）. The expression of TFF1 in gastric mucosa with atypical hyperplasia （0.57 ± 0.03） was significantly higher than that in normal gastric mucosa （P 〈 0.001）. No TFF1 was expressed in intestinalized gastric mucosa. There was no statistically significant difference between the expressions of TFFI in gastric mucosa around the intestinalized tissue （0.45 ± 0.07） and normal gastric mucosa （P 〉 0.05）. CONCLUSION： TFF1 is expressed mainly in epithelial cytoplasm of the mucosa in gastric body and antrum. Its main pattern is TFF1 compound, which may have a greater biological activity than monomer and dimer. The expression of TFF1 in peripheral mucosa of gastric ulcer is higher than that in mucosa 5 cm beyond the ulcer, indicating that TFF1 plays an important part in protection and restitution of gastric mucosa. The expression of TFF1 is increased in peripheral tissues of gastric carcinoma and gastric mucosa with atypical hyperplasia, but is decreased in cancer tissues, implying that TFF1 may be related to suppression and differentiation of carcinoma. The weaker expression of TFF1 in poorly-differentiated carcinoma may be related to the destruction of glands and cells in cancer tissues and the decrease in secretion of TFF1.

Suppression subtractive hybridization for identifying differentially expressed genes in renal cell carcinoma

Objective To construct a renal cell carcinoma (RCC) cDNA subtractive library using suppression subtractive hybridization.Methods Polyadenylated RNA ［Poly (A)+ RNA］ was isolated from tissues of RCC and normal kidney, and single-strand cDNAs and double-strand cDNAs were synthesized in turn. RCC cDNAs were divided into two groups and ligated to the specific adaptors l and 2, and then hybridized with normal kidney cDNA twice with two rounds of suppression PCR. Second round PCR products were cloned to T/A plasmid vectors to set up the subtractive library. One hundred clones were randomly picked to perform enzyme digest analysis, and some underwent sequence analysis and Northern blot to identify RCC specifically expressed genes. SMART RACE procedure was operated to clone full length novel RCC specifically expressed genes.Results A human RCC subtractive library with high subtractive efficiency was successfully set up. The amplified library contains 350 positive clones. Random analysis of 100 clones with enzyme restriction showed that 85 plasmids in the clones contained 50-400?bp inserts. Sequence analysis was performed for 10 clones. All the 10 sequences were unknown before and derived from 6 unique, novel genes among which the cDNA insert RCC18 had five copies. Northern blot analysis showed that RCC18 cDNA was highly expressed in RCC, but no signal could be detected in normal kidney. Using SMART RACE technique, we obtained the full length of the novel gene RCC18.Conclusions The constructed cDNA subtractive library of human RCC is a highly efficient one and lays a solid foundation for large scale screening and cloning new and specific oncogenes or tumor suppressor genes of RCC. The novel specifically expressed genes provided an important clue for studying the mechanisms of occurrence and development of RCC.