METHODS: Colon tissues (normal and cancerous) were homogenized and the proteins were extracted using three protein extraction buffers. The extraction buffers were used in an orderly sequence of increasing extraction strength for proteins with hydrophobic properties. The protein extracts were separated using the SDS-PAGE method and the images were captured and analyzed using Quantity One software. The target protein bands were subjected to in-gel digestion with trypsin and finally analyzed using an ESI-ion trap mass spectrometer.
RESULTS: A total of 50 differentially expressed proteins in colonic cancerous and normal tissues were identified.
CONCLUSION: Many of the identified proteins have been reported to be involved in the progression of similar or other types of cancers. However, some of the identified proteins have not been reported before. In addition, a number of hypothetical proteins were also identified.
CLINICAL PICTURE: This is a report of a case of metastatic adenocarcinoma of colorectal origin to the paranasal sinuses in a 52-year-old female who was previously treated for adenocarcinoma of the sigmoid colon. A histologic study of the surgical specimen from the sinonasal cavity demonstrated a tumour identical to the patient's prior primary tumour of the colon. The sinonasal neoplastic tissue showed marked positivity for carcinoembryonic antigen and expressed cytokeratin 20, which differentiates metastatic colonic adenocarcinoma from ITAC.
TREATMENT/OUTCOME: The patient received palliative radiation but died 3 months after the diagnosis.
CONCLUSION: Distinguishing metastatic adenocarcinoma from gastrointestinal tract from ITAC can be difficult. In view of the resemblance, immunohistochemical staining can help in differentiating them. It is important to recognise these as metastatic lesions as the treatment is mainly palliative.