Each treatment group (optical imaging because of its low cells absorption and deep cells penetration properties . injected with cyclic form of ApoPep-1 at 1 week after combined treatment with cisplatin plus cetuximab. Correlation analysis exposed that imaging signals Oroxin B by cyclic ApoPep-1 Oroxin B at 1 week after treatment with cisplatin plus cetuximab in combination were most closely related with tumor volume changes (r2?=?0.934). These results demonstrate that apoptosis imaging using Apopep-1, especially cyclic ApoPep-1, Oroxin B is definitely a sensitive and predictive tool for early decision on belly tumor response after anti-cancer treatment. Introduction Gastric malignancy is the second leading cause of cancer death worldwide . Single-agent chemotherapy for advanced gastric malignancy includes capecitabine or 5-fluorouracil, while combination therapy includes cisplatin plus 5-fluorouracil or cisplatin plus capecitabine . Unfortunately, gastric malignancy has shown low responsibility to chemotherapy. The response rate of advanced gastric malignancy ranges from 10C30% for single-agent therapy and 30C60% for combined chemotherapy . In addition, molecular targeted medicines such as cetuximab (anti-epidermal growth element receptor antibody) and trastuzumab (anti-Her2 receptor antibody) have been used in combination with chemotherapy, resulting in diverse response rates C. In the light of these low response rates, monitoring and early decision of belly tumor Rabbit polyclonal to ADPRHL1 response after treatment with anti-cancer medicines is therefore extremely important in the management of malignancy therapy. Traditionally, decision on tumor response has been performed by measuring the changes in tumor size using computed tomography (CT). Such a tumor size-based decision on tumor response, however, is usually possible at two months after the start of treatment. According to the recommendations of Response Evaluation Criteria in Solid Tumors (RECIST), when there is at least 30% reduction in tumor size, the treatment is considered as a partial response, while when there is a 20% or higher increase in tumor size, it is defined as a progressive disease . To reduce the consuming of time and cost for an anti-tumor therapy, it is required to make the proceed/no-go decision on the therapy earlier than the current method based on tumor size measurement by CT. Measuring the uptake of 18F-fluorodeoxyglucose (18F-FDG) by tumor using positron emission tomography (PET) imaging offers enabled us to make an earlier decision on tumor response after anti-tumor therapy than size-based CT imaging. 18F-FDG uptake of tumor cells is decreased from the reduction in the rate of metabolism and burden of tumor cells after chemotherapy. However, it is known the uptake of 18F-FDG primarily depends on histopathological types of gastric malignancy. For example, Signet-ring cell carcinoma and mucinous adenocarcinoma uptake 18F-FDG at low levels due to low levels of GLUT-1 transporter , . These features make decision on gastric malignancy response by 18F-FDG uptake limited. In addition, some types of tumor, such as breast cancer, display metabolic flare, a temporary increase of 18F-FDG uptake Oroxin B after chemotherapy, which is definitely hard to discriminate it from tumor relapse . When tumor cells are treated with chemotherapy and molecular targeted medicines, they generally pass away of apoptosis C. Apoptotic cell death appears to happen before anatomical switch or reduction in tumor size , . With this respect, imaging of apoptosis would enable us to decide whether tumor is definitely responsive to a treatment at an earlier stage than does imaging of size reduction. Moreover, apoptosis directly represents tumor cell death, while 18F-FDG uptake represents tumor rate of metabolism and thus indirectly represents tumor cell death. Apoptotic cells put signatures or biomarkers on their surface, such as phosphatidylserine and histone H1, that are Oroxin B little or absent on the surface of healthy cells C. Apoptosis imaging probes such as annexin V and dipicoyl zinc amide that bind to phosphatidylserine have been exploited for monitoring tumor cell apoptosis imaging signals of apoptosis obtained by the uptake of linear and cyclic (disulfide-bonded) form of ApoPep-1 at an early stage after treatment are correlated with changes in tumor volume later and are able to make an early decision on tumor response possible. Materials and Methods Synthesis and fluorescence labeling of peptides Linear (CQRPPR) or cyclic (CQRPPRC, cyclization via disulfide bonding at amino and carboxy termini) form of ApoPep-1.