The Expression And The Clinical Significance Of IMP3 In Colorectal Cancer Tissue

BACKGROUD Colorectal cancer (CRC) is the third most common cancers in the worldwide, unlike the developed countries, the morbidity and mortality in china are still rising. Although resection of primary CRC can be curative when the disease is localized, distant metastasis remains the main cause of treatment failure and death from cancer. It is a focus to find the molecular markers, which can accurately present the risk of colorectal cancer, which is an important role for the accurate screening of colorectal cancer patients with potential risk of recurrence and metastasis. However, recent studies revealed that CRC progression is directed in many aspects by a circuitous ecosystem consisting of an extracellular matrix (ECM) scaffold populated by cancer-associated fibroblasts (CAFs), vascular space-related cells, and diverse innate and adaptive immune response cells. The modern evolution of treatment of CRC tends to be a multidisciplinary management to improve this result. Advances in preoperative chemotherapy and radiation have reduced the disease recurrence and increased survival in high risk disease. The American joint committee on cancer (AJCC) TNM stage is the most important prognostic factor for patient with CRC. Accurate preoperative staging of CRC is essential for deciding on treatment strategies in the multidisciplinary management. The most frequently used imaging modalities for preoperative staging of CRC are ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET)/CT. these imaging modalities are unreliable in identifying lymph node metastasis (accuracies of MRI are 39～95%, CT are 22～73%, US are 62～83%). Inaccurate radiological staging might result in inappropriate preoperative chemotherapy and radiotherapy. Therefore, the need for additional predictive marker for preoperative staging that would enable better categorization of the patients and eventually provide a guide for individualized therapy. Insulin-like growth factor Ⅱ mRNA-binding protein 3 (IMP3) is a member of the insulin-like growth factor (IGF) mRNA binding protein (IMP) family that consists of IMP1, IMP2 and IMP3. It has been reported that IMP3 was an oncofetal protein which has been found only in human cancer tissues and early human embryogenesis, but not in normal tissue of adults. Further studies have shown that IMP3 promotes tumor cell proliferation, adhesion, and invasion. IMP3 was correlated with malignancy perhaps the advanced and aggressive malignancy. In the past decades, treatment and molecular characteristics relating to prognosis of CRC manly focused on the malignant cancer cells. However, recent studies revealed that CRC progression was directed in many aspects by tumor stroma. Tumor stroma is pivotal not only to the tumor initiation malignant progression and metastasis, but also to the response to therapy. Recent studies reveal that IMP3 expression in tumor cells was a marker of unfavorable prognosis in CRC patients. However, little is known about whether stromal expression of IMP3 is of CRC clinical relevance. At present, more and more research found that there are many consistency molecule expressions in endoscopic biopsy specimens and postoperative pathological specimens, and studies have shown that the characteristics of endoscopic biopsy specimens can almost represent the tumor as a whole. However, the expression status and clinical implication of IMP3 in biopsy specimens have not yet been studied also. ABSJECTIVE we probed the expressions of IMP3 in postoperative resected tumor tissue and the preoperative biopsy specimens and analyzed the correlation between IMP3 expression and the clinicopathologic parameters to address whether the presence of IMP3 expression could predict advanced CRC and bad prognosis. METHODS IMP3 expression in 130 surgically resected primary CRCs in the third affiliated hospital of southern medical university department of general surgery from 2004-2014was investigated by immunohistochemistry. We gathered age, gender, tumor location, tumor size, histological grade, histological subtype, T classification, TNM stage, tumor border, tumor budding and lympho-vascular invasion of the 130 CRC patients and followed up the survival prognosis of these patients. The expression levels of IMP3 in tumor cells and tumor stroma were correlated with clinicopathological features and patient survival. We investigated the expression of mRNA and IMP3 protein in the colon cancer cell lines and normal colon mucosa tissue using the RT-PCR and Western blot. We examined IMP3 expression in paired biopsy and resection specimens of CRC and determined the correlation of IMP3 expression with clinicopathological parameters (age, gender, tumor location, tumor size, histological grade, histological subtype, T classification, TNM stage, tumor border, tumor budding and lympho-vascular invasion). We aim to address whether the presence of IMP3 expression in preoperative biopsies of CRC could predict lymph node metastasis and TNM stage. In our study, we collected 71 cases of preoperative abdominal CT scan outcomes, the prognostic effect of IMP3 expression and CT scan was compared. RESULTS One hundred and thirty CRC patients were available for review from 2004 to 2014 (mean age,61.1 years; range,24-88 years). The end date of the follow-up study for conducting the analysis was Jan 1st,2015 (mean time,52.5 months; range,1-132 months). During follow-up,58 had been followed for >60 months or until death, at the end of follow-up,27 patient died,103 patient remained alive, tumoral expression of IMP3 (IMP3 stained more than 10% of tumor cells) was detected in 94/130 CRAs (72.3%). Tumoral expression of IMP3 was significantly related to T-classification (T1-2 vs T3-4, P=0.027), TNM stage (Ⅰ-Ⅱ vs Ⅲ-Ⅳ, P=0.011), Lymph node metastasis (absent vs present, P=0.048) and tumor budding (low vs high, P=0.005). It did not showed a significantly correlation of IMP3 expression with age (P=0.445), gender (P=0.432), tumor location (P=0.247), tumor size (P=0.171), histological grade (P=0.122), histological subtype (P=0.759), lympho-vascular invasion (P=0.116), and tumor border (P=0.055). IMP3 expression was not only detected in the tumor cells region, but also in the cytoplasm of tumor stroma cells. Stromal expression of IMP3 (stroma cells with exactly cytoplasmic staining) was found in 24/130 patients (18.5%), negative in 106/130 patients (81.5%). Stromal expression of IMP3 was correlated with TNM stage (III-IV, P=0.003), lymph node metastasis (P=0.006), Lympho-vascular invasion (p=0.003), tumor border (infiltrating vs pushing, P=0.013). It did not showed a significantly correlation with age (P=0.244), gender (P=0.181), tumor location (P=0.104), tumor size (P=0.497), histological grade (P=0.566), histological subtype (P=0.130), T-classification (T1-2 vs T3-4, P=0.121), and tumor budding (P=0.371). Of the 24 stroma-positive specimens,18 are also tumor cell-positive cases, but we did not find any relationship between them (P=0.87). Further study indicated that patients with IMP3 expressed in tumor cells and tumor stroma had a bad survival rate of P=0.02 and P=0.06, respectively. Moreover, tumoral expression of IMP3 (P=0.029) and TNM stage (P=0.045) were independent prognostic factors in CRC. In the biopsy specimens, IMP3 positive expres-sion was observed in 56 of 71 cases (78.9%) whereas negative expression was observed in 15 of 71 cases (21.1%). In the resection specimens, IMP3 positive expression was detected in 83.1% cases (59/71) whereas negative expression was detected in 16.9% cases (12/71). The Spearman correlation test documented the existence of a strong linear correlation between the percentage of IMP3-positive cells in the biopsy and resection specimen (r= 0.629; P< 0.001). IMP3 expression in biopsy specimens was significantly related to lymph node metastasis (P= 0.004), TNM stage (P= 0.005) and tumor bud ding (P= 0.001). In contrast, there was no association between IMP3 expression and age (P= 0.458), gender (P= 0.987), tumor location (P= 0.708), tumor size (P= 0.130), histological grade (P= 0.640), histological subtype (P= 0.257), T classification (P= 0.115), tumor border (P= 0.236) and lympho-vascular invasion (P= 0.058). IMP3 expression in resection specimens was significantly related to histological grade (P= 0.043), T classification (P= 0.035), lymph node metastasis (P= 0.023), TNM stage (P= 0.007), tumor border (P= 0.049) and tumor budding (P= 0.012). In contrast, there was no association between IMP3 expression and age (P= 0.233), gender (P= 0.788), tumor location (P= 0.718), tumor size (P= 0.291), histological subtype (P= 0.846) and lympho-vascular invasion (P= 0.311). For lymph node metastases, IMP3 expression in the biopsy had a sensitivity of 93.9%, a specificity of 34.2%, a PPV of 55.4%, and an NPV of 86.7%, whereas CT had a sensitivity of 45.2%, a specificity of 72.7%, a PPV of 60.9%, and an NPV of 58.5%. IMP3 expression in the biopsy had a higher sensitivity and a lower specificity than CT scan for lymph nodal metastases. CONLUSION Herein we describe for the first time that IMP3 stains in tumor stromal components of CRC. Tumoral expression of IMP3 had a relationship with T classification, TNM stage, lymph node metastasis, tumor budding. Stromal expression of IMP3 correlates with lymph node metastasis and high tumor stage. Moreover, IMP3 expression in tumor cells predicts a poor survival of CRCs. Our results firstly confirm that IMP3 expression in biopsy specimens of CRC patients was significantly associated with lymph node metastasis and TNM stage. IMP3 expression in biopsy specimens could be used to predict lymph node metastasis and TNM stage in CRC patients. IMP3 may be a promising drug target in the treatment of CRC. Further studies will be necessary to elucidate the exact mechanism of IMP3 action in tumor pathogenesis.