DISCOVERY OF NEW SECRETED PROTEINS OF PANCREATIC CANCER

血清肿瘤标志物的鉴定可显著提高肿瘤的早期诊断、有效评估治疗和早期发现肿瘤复发的能力。这种潜力通过前列腺特异性抗原（PSA）的发现得到了最完美的展示，PSA显著地促进了前列腺癌的筛查和监测。我们开发了一种分离新的血清肿瘤标志物的方法。我们建议使用分子生物学技术来筛选肿瘤的分泌蛋白，这些蛋白可以作为早期发现癌症的标记物。鉴别胰腺癌的一种或几种标志物可能对这种疾病的治疗具有深远的意义。如果我们取得成功，血清标记物将首次为一种简单、快速、廉价的胰腺癌筛查方法提供机会。在治疗过程中对疾病的监测和管理将得到显著加强，在肿瘤负荷较低时可以迅速发现早期复发。具体目标1：利用编码酵母分泌蛋白的SUC2基因，对信号序列诱捕技术进行修改，确认初步实验。在这个系统中，只有被含有分泌信号序列的cdna转化的酵母才能在含有蔗糖作为糖的唯一来源的培养皿上生长成菌落。具体目标2：我们将构建一个富含胰腺特异性基因的人胰腺癌cDNA文库，并将该文库置于我们基于酵母的信号序列陷阱载体中，以鉴定编码分泌蛋白的基因。特异性目的3：在确定候选cdna后，我们将进一步通过dot blotting和DNA测序筛选出新的胰腺特异性基因，我们将克隆全长cdna来制作针对基因产物的抗体。特异性目标4：对于似乎是胰腺特异性的抗体（理想情况下是胰腺癌选择性蛋白），将开发ELISA来检查胰腺癌患者和正常人血清样本中胰腺特异性分泌蛋白的存在。

The identification of serum tumor markers can markedly enhance the ability for early diagnosis, efficient assessment of treatment and early discovery of recurrence of cancers. This potential has been most elegantly shown through the discovery of prostate-specific antigen (PSA) which has markedly advanced screening and monitoring of prostate cancer. We have developed an approach to isolate new serum tumor markers of cancer. We propose using molecular biology techniques in order to screen for secreted proteins of tumors that can be used as markers for early detection of cancer. Identification of one or several markers of pancreatic cancer could have profound implications for the management of this disease. If we are successful, the serum markers will provide the first opportunity for a simple, rapid, inexpensive method of screening for pancreatic cancer. Monitoring and management of the disease during therapy would be markedly enhanced and early recurrence could be rapidly detected when tumor burden is low. Specific Aim 1: Confirmation of preliminary experiments using a modification of the signal sequence trap technique, utilizing the SUC2 gene encoding a secreted protein of yeast. In this system only the yeast which have been transformed with cDNAs containing secretory signal sequences can grow into colonies on the plates which contain sucrose as the only source of sugar. Specific Aim 2: We will construct a human pancreatic cancer cDNA library which has been enriched for pancreatic-specific genes, and this library will be placed in our yeast based signal sequence trap vector in order to identify genes encoding secreted proteins. Specific Aim 3: After identifying candidate cDNAs, we will further select for novel pancreatic-specific genes by dot blotting and DNA sequencing, and we will clone full-length cDNAs to make antibodies against the gene products. Specific Aim 4: For antibodies that appear to be pancreatic-specific (and ideally, pancreatic cancer-selective protein), an ELISA will be developed to examine for the presence of the pancreatic-specific, secreted protein in serum samples from pancreatic cancer patients as well as normal individuals.