Fei-Hua Qiu

The proto-oncogene c-kit encodes a transmembrane kinase which is related to the receptors for colony-stimulating factor type 1 and platelet-derived growth factor, as well as to the immunoglobulin superfamily. Antibodies specific for the kinase domain of the P80 gag-kit protein of the Hardy-Zuckerman 4 feline sarcoma virus were prepared. These kit-specific antibodies were used to identify and characterize the c-kit protein in cat brain tissue. The c-kit protein product displays an autophosphorylating activity in immune complex kinase assays, and, in turn, this activity was used to identify the c-kit protein in different tissues. In cat brain, a single 145-kilodalton (kDa) glycoprotein was detected. Its N-linked carbohydrates were found to be sensitive to digestion with the endoglycosidases (neuraminidase, endoglycosidase F, and endoglycosidase H), indicating hybrid and/or complex and high-mannose structures. A partial purification of the c-kit protein was achieved by wheat germ agglutinin affinity chromatography, and the autophosphorylating activity of the partially purified c-kit protein was characterized and found to be specific for tyrosine. The kit antibodies cross-react with the murine c-kit protein product, and variant c-kit proteins in different mouse tissues were identified, with sizes of about 145 kDa (brain), 160 kDa (spleen), and 150 kDa (testis).

The HZ5-feline sarcoma virus (FeSV) is a new acute transforming feline retrovirus which was isolated from a multicentric fibrosarcoma of a domestic cat. The HZ5-FeSV transforms fibroblasts in vitro and is replication defective. A biologically active integrated HZ5-FeSV provirus was molecularly cloned from cellular DNA of HZ5-FeSV-infected FRE-3A rat cells. The HZ5-FeSV has oncogene homology with the fms sequences of the SM-FeSV. The genome organization of the 8.6-kilobase HZ5-FeSV provirus is 5' delta gag-fms-delta pol-delta env 3'. The HZ5-and SM-FeSVs display indistinguishable in vitro transformation characteristics, and the structures of the gag-fms transforming genes in the two viruses are very similar. In the HZ5-FeSV and the SM-FeSV, identical c-fms and feline leukemia virus p10 sequences form the 5' gag-fms junction. With regard to v-fms the two viruses are homologous up to 11 amino acids before the C terminus of the SM-FeSV v-fms protein. In HZ5-FeSV a segment of 362 nucleotides then follows before the 3' recombination site with feline leukemia virus pol. The new 3' v-fms sequence encodes 27 amino acids before reaching a TGA termination signal. The relationship of this sequence with the recently characterized human c-fms sequence has been examined. The 3' HZ5-FeSV v-fms sequence is homologous with 3' c-fms sequences. A frameshift mutation (11-base-pair deletion) was found in the C-terminal fms coding sequence of the HZ5-FeSV. As a result, the HZ5-FeSV v-fms protein is predicted to be a C-terminally truncated version of c-fms. This frameshift mutation may determine the oncogenic properties of v-fms in the HZ5-FeSV.

Tyrosine protein kinase c-Met, encoded by the Met gene, is a membrane-associated receptor tyrosine kinase that is often aberrantly expressed in a wide range of tumors. The development of imaging probes specifically targeting c-Met is critical for improving cancer diagnostics. In this study, we successfully designed and fabricated an aptamer molecular imaging probe ([68Ga]Ga-NOTA-SL1) with high radiochemical purity (RCP), good stability in vitro, and high affinity for c-Met expressed tumors. As shown by the micro-PET/CT scanning, [68Ga]Ga-NOTA-SL1 efficiently imaged tumor models with varying c-Met expression. The quantitative analysis of micro-PET/CT showed tumor uptake of [68Ga]Ga-NOTA-SL1 in the HCC827 tumor models (30 min, 2.93 ± 0.64%ID/g; 60 min, 2.03 ± 0.67%ID/g; 90 min, 1.63 ± 0.61%ID/g), PC-9 tumor models (30 min, 2.1 ± 0.72%ID/g; 60 min, 1.7 ± 0.56%ID/g; 90 min, 1.33 ± 0.38%ID/g), and HCT116 tumor models (30 min, 1.4 ± 0.17%ID/g; 60 min, 1.23 ± 0.15%ID/g; 90 min, 0.97 ± 0.21%ID/g). The results of immunohistochemistry (IHC) further confirmed the targeting ability of [68Ga]Ga-NOTA-SL1 to c-Met from a molecular pathological perspective. The probe effectively imaged c-Met-positive tumors and demonstrated a favorable metabolism profile and targeting performance in non-small cell lung cancer (NSCLC) or colorectal cancer tumor models. Consequently, this probe shows promise as an imaging agent capable of providing valuable diagnostic insights into tumors with aberrant c-Met expression.

OBJECTIVE: To observe the roles of c-myc gene amplification, MTS1/p16 gene alternation, and HBV infection in the pathogenesis and progression of hepatocellular carcinoma (HCC). METHODS: A d-PCR-PAGE-laser scanning technique was used to define amplifications of c-myc oncogene. Alternations of MTS1/p16 gene exon1 and exon2 were analysed by PCR and single-strand conformation polymorphism (SSCP) silver stain method. HBV-DNA was assayed by PCR. RESULTS: (1)The positive rates of c-myc gene amplification of HCCs and their paired non-cancerous liver tissues were 44.83% (13/29) and 51.72% (15/29). The discrepancies between them were not significant (P>0.05), but they were both significantly higher than that of cirrhotic liver tissues (8.33%, 1/12, P<0.05). (2)A total of 3 homozygous deletions and no mutations of MTS1/p16 gene exon1 and exon2 in HCCs were found in the subset of HCCs. (3)The discrepancies of the positive rates of HBV-DNA among normal liver (14.29%, 2/14), cirrhotic liver (66.67%, 8/12) and HCCs (96.55%, 28/29) were significant (P<0.001). Moreover, the HBV-DNA positive rates increased according to the development of liver lesions (b=0.3986, P<0.001). CONCLUSIONS: (1)C-myc gene amplification and HBV infection are closely related to the development and progression in a subset of HCCs. However, c-myc gene amplification does not correlate with the HBV infection in HCCs. (2)The homozygous deletions and mutations of MTS1/p16 gene are infrequently encountered in the subset of HCCs.