KOC (K homology domain containing protein overexpressed in cancer): a novel molecular marker that distinguishes between benign and malignant lesions of the pancreas

Diagnostic utility of IMP3 in segregating metastatic melanoma from benign nevi in lymph nodes

Depending on the Breslow depth of the primary melanoma, sentinel lymph node biopsy is considered as standard of care for the staging of cutaneous melanoma, and is one of the most important prognostic factors. The histologic analysis of these specimens becomes difficult to interpret when benign intranodal nevic cells mimic metastases. Insulin-like growth factor-II messenger RNA (mRNA)-binding protein-3 (IMP3), also known as K homology domain-containing protein overexpressed in cancer or L523S, is a member of the insulin-like growth factor-II mRNA-binding protein family and has been shown to have diagnostic utility in distinguishing cutaneous melanoma from benign nevi. In this study, 43 sentinel lymph node biopsy specimens, including 13 with benign intranodal nevi and 30 with metastatic melanoma (two cases containing both benign nevi and metastatic melanoma), from 41 patients were immunohistochemically analyzed with a monoclonal antibody against IMP3. None of the benign intranodal nevi expressed IMP3, whereas 21 out of 30 (70%) of the lymph nodes containing metastatic melanoma did. It seems that IMP3 is helpful in distinguishing benign intranodal nevi from metastatic melanoma in sentinel lymph node biopsy specimens, and could be a valuable diagnostic adjunct in sentinel lymph node biopsy assessment in which questions arise as to the malignancy of the melanocytes present.

IMP3 expression in human ovarian cancer is associated with improved survival

The insulin-like growth factor-II mRNA-binding protein IMP3 plays an important role in embryogenesis and recent reports suggest an involvement in tumorigenesis. Although IMP3 expression has been well studied in mouse and human fetal and adult gonads, its role in ovarian cancer is unknown. We investigated the expression of IMP3 at protein and mRNA levels in a cohort of primary ovarian carcinomas and in 11 ovarian cancer cell lines. Western blot analysis revealed an expression of IMP3 in all ovarian cancer cell lines and immunohistochemistry demonstrated a positive cytoplasmic staining in 32 of 68 carcinomas (47%). In contrast, epithelium of borderline tumors, as well as, benign ovarian lesions and normal ovaries exhibited only weak or no IMP3 expression. In univariate Kaplan-Meier analysis, IMP3 protein expression was significantly associated with better overall survival (P=0.048). To confirm these findings, we further determined IMP3 mRNA expression in 43 ovarian cancer specimens by real time quantitative reverse transcription-polymerase chain reaction. A significant correlation between protein and mRNA levels (r=0.414, P=0.006), as well as a correlation of IMP3 mRNA expression with patient overall survival (P=0.044), was observed. Our results demonstrate that IMP3 is expressed in a subpopulation of ovarian cancer and a marker of good prognosis.

IMP3 is a novel biomarker for triple negative invasive mammary carcinoma associated with a more aggressive phenotype

IMP3, an oncofetal protein, is a member of the insulin-like growth factor-II (IGF-II) mRNA-binding protein family. Its relevance as a novel biomarker in lung, pancreatic, renal, and cervical adenocarcinoma was recently revealed. However, its role in breast carcinogenesis and tumor progression is not yet established. Basal-like carcinoma was initially identified by gene expression profiling. It accounts for 15% to 30% of all breast cancers. These tumors express basal epithelial markers including cytokeratin 5 but lack expression of the estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2), therefore, are often referred to as triple negative breast cancer. They have been found to be associated with a worse overall and disease-free survival. In this retrospective study, we examined the IMP3 expression in invasive ductal carcinoma of the breast and correlated its expression with morphological and biologic prognostic factors. The study group comprised 138 cases of invasive ductal carcinoma retrieved from the surgical pathologic files for a 10-year period from 1997 to 2006. Survival data and clinical stage were available on all 138 patients. Tumor characteristics including size, grade, lymphovascular invasion, necrosis, lymph node metastasis, estrogen receptor, progesterone receptor, and HER2 status were obtained from pathologic reports. Immunohistochemistry was performed on formalin-fixed paraffin-embedded tissue using mouse monoclonal antibody against IMP3 and CK5/6. Of the 138 breast cancer cases, IMP3 expression was seen in 45 (33%). Twenty-five of the IMP3+ cases were triple negative. We found significant correlation between IMP3 expression and higher grade (P = .001), necrosis (P< .0001) triple negative, and CK5/6 expression (P < .0001 for each). Cox multivariate analysis showed a hazard ratio of IMP3 expression at 3.14 (P = .05). IMP3 is a novel biomarker for triple negative (basal-like) invasive mammary carcinoma, and its expression is associated with a more aggressive phenotype and decreased overall survival.

Diffuse expression of RNA-binding protein IMP3 predicts high-stage lymph node metastasis and poor prognosis in colorectal adenocarcinoma

BACKGROUND

IMP3 (insulinlike growth factor II mRNA-binding protein 3) is a newly identified oncofetal RNA-binding protein that is involved in cell growth and cell migration during the early stages of embryogenesis. This study sought to elucidate its role in tumor progression and prognosis of colorectal adenocarcinoma (CRA).

METHODS

IMP3 expression in 186 surgically resected unifocal primary CRAs was analyzed by immunohistochemistry. The proportions of tumor cells positive for IMP3 were scored into diffuse (> or =50%), focal or heterogeneous (10-50%), and trace (<10%), and the expression levels were correlated with clinicopathologic features and patient survival.

RESULTS

Cytoplasmic immunoreactivity for IMP3 was diffuse in 66 (35%), focal or heterogeneous in 38 (21%), and trace in 34 (18%) samples. No staining was seen in the adjacent nontumorous tissue. Diffuse IMP3 expression correlated with large tumor (>3 cm, P = .0452), high-stage tumor (IIIa-IV, P = .0417), lymph node metastasis (P = .0232), high lymph node ratio (LNR > or = .7, P = .0016), and lower 5-year survival (P = .0012). Further analysis showed that patients with high-stage CRA and diffuse IMP3 expression had the worst survival rate (P < .0001)-far worse than those without diffuse IMP3 expression (P = .0038). Moreover, multivariant analysis showed diffuse IMP3 expression, serosal invasion, LNR, tumor stage, and adjuvant chemotherapy were independent prognostic factors in CRA.

CONCLUSION

Diffuse IMP3 protein expression correlates with invasion and aggressiveness during cancer growth and metastasis, and it is an important prognostic factor of CRAs.

An oncofetal protein IMP3: a new molecular marker for the detection of esophageal adenocarcinoma and high-grade dysplasia

Accurate diagnosis of dysplasia and adenocarcinoma in patients with Barrett esophagus is critical for clinical decision-making and patient management. IMP3 is an oncofetal protein and has been demonstrated to be associated with aggressive tumor behavior. The aim of this study was to establish the expression pattern and diagnostic value of IMP3 in Barrett esophagus, dysplasia, and carcinoma. A total of 217 cases (resection, n=56; biopsy, n=161) with 302 lesions (invasive esophageal adenocarcinoma, n=147; metastatic esophageal adenocarcinoma, n=14; high-grade dysplasia of the esophagus, n=52; low-grade dysplasia of the esophagus gland, n=21; and Barrett esophagus, n=68) were examined by immunohistochemistry for IMP3 expression. IMP3 showed strong cytoplasmic granular staining in 138 of 147 (94%) of invasive esophageal adenocarcinomas, 13 of 14 (93%) of metastatic esophageal adenocarcinomas, and 49 of 52 (94%) of high-grade dysplasias. In contrast, 3/21 (14%) of low-grade dysplasia and 5/68 (7%) Barrett esophagus were positive for IMP3. Expression of IMP3 was not found in adjacent benign squamous and glandular mucosa. Our findings indicate that IMP3 is a highly sensitive and specific biomarker for the diagnosis of invasive esophageal adenocarcinoma and high-grade dysplasia. The data also suggest that IMP3, an oncofetal protein, may play an important role in malignant transformation in esophageal adenocarcinoma.

Prognostic significance of insulin-like growth factor II mRNA-binding protein 3 expression in gastric adenocarcinoma

BACKGROUND

Insulin-like growth factor II mRNA-binding protein (IMP) 3 is expressed in embryonic tissues and multiple cancers. The aim was to establish the prognostic value of IMP-3 expression in gastric adenocarcinoma.

METHODS

IMP-3 expression in resected gastric adenocarcinomas was analysed by immunohistochemistry.

RESULTS

IMP-3 was expressed in 183 (58.1 per cent) of 315 tumours. Expression was associated with older age (P < 0.001), larger tumour size (P = 0.009), deep tumour invasion (P < 0.001) and lymph node metastasis (P < 0.001). IMP-3-positive tumours were associated with poorer 5-year survival than negative tumours at all stages (stage I, 82 versus 97 per cent; stage II, 55 versus 78 per cent; stage III and IV, 11 versus 25 per cent; P = 0.005, P = 0.033 and P = 0.036 respectively). Multivariable analysis identified IMP-3 (hazard ratio (HR) 1.93), depth of tumour invasion (HR 3.69, 9.77 and 10.69 for pathological tumour stage (pT) 2, pT3 and pT4 respectively versus pT1), and lymph node metastasis (HR 1.57, 3.29 and 3.40 for pathological node stage (pN) 1, pN2 and pN3 respectively versus pN0) as independent prognostic factors.

CONCLUSION

IMP-3 expression correlates with the metastatic potential of gastric adenocarcinoma and is an independent prognostic factor.

Epithelial-mesenchymal transition markers in pancreatic ductal adenocarcinoma

OBJECTIVES

Expression of transcription factors that mediate epithelial-mesenchymal transition (EMT), such as Twist and Slug, is correlated with poor prognosis in many tumor types. Selected EMT markers were studied in a series of pancreatic ductal adenocarcinomas (PDAs) and benign pancreatic tissues to determine whether expression levels correlated with diagnosis, histologic grade, or patient outcome.

METHODS

Immunohistochemical stains for Twist, Slug, and N-cadherin were performed using a tissue microarray containing 68 PDAs and 38 samples of normal pancreas or chronic pancreatitis tissues.

RESULTS

Twist and Slug were identified in both the nucleus and cytoplasm of benign pancreatic ductal epithelium, chronic pancreatitis, and PDA. Compared with normal ductal epithelium, nuclear levels of Twist are decreased in PDA. None of the other EMT markers showed significant differences in staining indices among the diagnostic groups. There were no correlations between EMT marker expression and histologic grade. Epithelial-mesenchymal transition marker expression was not associated with N-cadherin expression, patient outcome, or duration of survival.

CONCLUSIONS

Decreased expression of nuclear Twist is observed in malignant pancreatic epithelium. However, use of Twist as a diagnostic marker is precluded because decreased expression is also seen in chronic pancreatitis. None of the markers studied were predictive of patient outcome.

Insulin-like growth factor mRNA binding protein 3 (IMP3) is differentially expressed in benign and malignant follicular patterned thyroid tumors

Insulin-like growth factor mRNA binding protein 3 (IMP3) is an mRNA-binding protein that regulates transcription of insulin-like growth factor II affecting cell proliferation during embryogenesis. It is highly expressed in carcinomas of the pancreas, stomach, colon, rectum, kidneys, uterine cervix, lung, and ovary. The purpose of our study was to evaluate IMP3 expression in thyroid follicular lesions, to determine whether it has a role in differentiating among these lesions, and to understand their biological relationships. We immunostained 219 thyroid lesions selected from our surgical pathology archives including 14 hyperplastic colloid nodules (CN), 19 Hashimoto's thyroiditis (HT), two Graves disease (GD), ten Hürthle cell adenoma (HCA), 20 follicular adenoma (FA), 37 conventional papillary thyroid carcinoma (PTC), 60 follicular variant of papillary carcinoma (FVPC), 19 Hürthle cell carcinoma (HCC), 32 follicular carcinoma (FC), and six poorly differentiated/anaplastic carcinoma. Immunohistochemistry was performed on formalin-fixed sections using monoclonal antibody to IMP3. Clinicopathological data were also reviewed. In all cases, residual thyroid tissue, CN, HT, GD, HCA, and FA were completely negative for IMP3 staining. Of the 60 FVPC, 23 tumors (38%) were positive for IMP3, with 13 of these (22%) showing very strong staining (3+). Of the 32 FC, 22 tumors (69%) were positive, with seven (22%) showing very strong staining (3+). Furthermore, 33 out of 37 cases (89%) of PTC were negative for IMP3. In all four PTC cases that did stain positive, staining was weak-moderate (1-2+). Similarly, 15 out of 19 cases (79%) of HCC were negative. No significant correlation was found between pathologic tumor characteristics and IMP3 expression in differentiated follicular pattern thyroid carcinoma. With 100% specificity and 69% sensitivity for FC as compared to FA and 100% specificity for FVPC, again compared to FA, IMP3 has the potential to be diagnostically useful in differentiating malignant and benign follicular pattern thyroid lesions. This study also points to a possible common biological relationship between FC and FVPC that requires further investigation.

Pancreatic intraepithelial neoplasia revisited and updated

Most pancreatic neoplasms are classified as ductal adenocarcinoma because they show a ductal phenotype, making a ductal origin very likely. The duct lesions that may give rise to pancreatic ductal adenocarcinoma have been called pancreatic intraepithelial neoplasia (PanIN). A classification system for these lesions distinguishes between three grades of PanIN. Molecular studies revealed that PanIN-2 and PanIN-3 lesions represent a distinct step towards invasive carcinoma. While high-grade PanINs are extremely rare in the normal pancreas, low-grade PanINs are common in individuals older than 40 years and may be associated with lobular fibrosis and intraductal papillary mucinous neoplasms of the gastric type. This disease spectrum has also been described in members of kindreds with familial pancreatic cancer. The natural history and cause of PanINs are unknown. As PanIN-1 lesions entail little risk, while PanIN-3 lesions are high-risk lesions, it would be of interest to target PanIN-2 lesions, which can be regarded as the starting point of progressive neoplastic changes that lead to invasive pancreatic ductal adenocarcinoma. Global gene expression analysis identified several differentially expressed genes which show enhanced expression in PanINs and may be used as potential biomarkers to facilitate diagnosis and therapy.

KOC (K homology domain containing protein overexpressed in cancer) and S100A4-protein immunoreactivity improves the diagnostic sensitivity of biliary brushing cytology for diagnosing pancreaticobiliary malignancies

Biliary tract brush cytology is one of the favored methods of evaluating lesions of the pancreatobiliary tract. However, although its specificity has been reported to be high (91-100%), the sensitivity is lower (30-88%). In this study we applied KOC and S100A4 protein immunocytochemistry to assess their potential use as adjunct markers in differentiating benign from malignant cells, and improve the diagnostic sensitivity of this method for pancreatobiliary malignancies. The authors examined KOC and S100A4 protein expression in 44 alcohol-fixed cytology specimens obtained by biliary brushings. Diagnoses included: (1) benign/atypical favor reactive (20 cases), (2) atypical/not diagnostic of malignancy (3 cases), and (3) suspicious for malignancy/malignant (21 cases). Alcohol-fixed Papanicolaou-stained slides (PAP) were stained with monoclonal antibody to KOC/L523S and polyclonal antibody to S100A4 protein. Results were recorded as negative or positive. Twenty-four cases were confirmed positive for adenocarcinoma and 20 cases were negative. The sensitivity and specificity of cytology was 83 and 95%, KOC showed a sensitivity of 92% and specificity of 95%. S100A4 protein showed a sensitivity of 79% and a specificity of 95%. The combined use of KOC and S100A4 protein showed a sensitivity of 100% and a specificity of 95%, respectively. The concurrent use of KOC and S100A4 protein improves the diagnostic sensitivity of biliary brushings cytology and demonstrates similar specificity as cytology alone in the diagnosis of pancreatobiliary malignancy.

Merkel cell carcinoma expresses K homology domain-containing protein overexpressed in cancer similar to other high-grade neuroendocrine carcinomas

Merkel cell carcinoma is an uncommon and aggressive primary cutaneous neuroendocrine carcinoma with a high rate of recurrence and metastasis. Optimal management is controversial; consequently, it is imperative to identify the signaling pathways involved in the pathogenesis of Merkel cell carcinoma so that effective therapeutic targeting agents can be developed. We previously reported that K homology domain-containing protein overexpressed in cancer is expressed in high-grade neuroendocrine carcinomas of the lung and extrapulmonary small cell carcinomas. The K homology domain-containing protein overexpressed in cancer (KOC), also known as L523S and IMP-3, is an insulin-like growth factor II messenger RNA-binding protein that promotes tumor cell proliferation by enhancing insulin-like growth factor II protein expression. Expression of KOC in Merkel cell carcinoma has not been investigated. We studied 20 Merkel cell carcinomas by immunohistochemistry using a monoclonal antibody against L523S/KOC. Of 20 Merkel cell carcinomas, 18 (90%) overexpressed KOC, with 11 (55%) overexpressing KOC in greater than 90% of tumor cells, 3 (15%) overexpressing KOC in 50% to 90% of tumor cells, 3 (15%) overexpressing KOC in 10% to 50% of tumor cells, and 1 (5%) overexpressing KOC in less than 10% of tumor cells. The immunostaining intensity was variable, with moderate to strong staining in 14 cases and weak staining in the remaining 4. Extent of expression of K homology domain-containing protein overexpressed in cancer predicted metastasis (P = .04) and was weakly correlated with increased tumor size (P = .08). In conclusion, Merkel cell carcinoma expresses K homology domain-containing protein overexpressed in cancer with an expression pattern similar to high-grade neuroendocrine carcinomas of the lung and extrapulmonary small cell carcinomas. We propose K homology domain-containing protein overexpressed in cancer as a potential target molecule for the treatment of high-grade neuroendocrine carcinomas, irrespective of anatomical location, and a potential marker to predict metastatic disease.

Combination of quantitative IMP3 and tumor stage: a new system to predict metastasis for patients with localized renal cell carcinomas

PURPOSE

To create an easily applicable system based on a combination of the quantitative level of IMP3 (an oncofetal protein) and tumor stage to more accurately predict postoperative metastasis of localized renal cell carcinoma.

EXPERIMENTAL DESIGN

Three hundred sixty nine patients with localized renal cell carcinoma (without metastasis during nephrectomy) were investigated by the use of survival analysis. The expression of IMP3 was evaluated by immunohistochemistry and quantitated with a computerized image analyzer. Based on combining quantitative IMP3 results with tumor staging (QITS system), patients were divided into four distinct risk groups for the development of metastasis.

RESULTS

The four groups of patients in the QITS system showed significant differences in their metastasis-free (P<0.0001) and overall survivals (P<0.0001). Almost all patients of group IV with localized renal cell carcinomas developed metastasis and died after nephrectomy. The 5- and 10-year metastasis-free survival rates for the QITS groups were as follows: for group I, 97% and 91%; II, 62% and 55%; III, 46% and 19%; and IV, 17% and 4%, respectively. The 5- and 10-year overall survival rates for the QITS groups were as follows: for group I, 89% and 72%; II, 58% and 41%; III, 38% and 17%; and IV, 14% and 4%, respectively.

CONCLUSIONS

The QITS is a simple and accurate system for the prediction of tumor metastasis. This system not only provides important prognostic information but also can be used at initial diagnosis of localized renal cell carcinoma to identify high-risk patients who may benefit from early systematic therapy.

RNA-binding protein insulin-like growth factor II mRNA-binding protein 3 expression promotes tumor invasion and predicts early recurrence and poor prognosis in hepatocellular carcinoma

Insulin-like growth factor II mRNA-binding protein 3 (IMP3) is an RNA-binding protein expressed in embryonic tissues and multiple cancers. To investigate the role of IMP3 in hepatocellular carcinoma (HCC), its protein expression in the surgically resected unifocal tumors of 377 HCC patients (296 men and 81 women) with ages ranging from 7 to 88 years (mean, 55.49 years) was analyzed by immunohistochemistry. IMP3 was expressed in 255 (67.6%) of 377 resected unifocal primary HCCs. IMP3 protein was predominantly expressed in tumor border and invasive front, and it was more abundant in the satellite nodules and tumor thrombi than in the main tumors. The expression correlated with high alpha-fetoprotein (>200 ng/mL, P < 1 x 10(-7)), larger tumor size (>5 cm, P = 0.006), high tumor grade (P < 1 x 10(-7)), and high tumor stage with vascular invasion and various degrees of intrahepatic metastasis (P < 1 x 10(-7)). IMP3 expression predicted early tumor recurrence (P < 1 x 10(-7)) and was a strong indicator of poor prognosis (P < 0.0001). Depletion of IMP3 with RNA interference in HCC cell line HA22T caused a decrease in cell motility, invasion, and transendothelial migration. Microarray analysis revealed that IMP3 depletion was associated with downregulation of multiple genes involved in tumor invasion.

CONCLUSION

Our results indicate that IMP3 plays an important role in tumor invasion and metastasis and is a strong prognostic factor for patients with HCC.

Differential diagnosis of pancreatic tumors by molecular analysis of clinical specimens

OBJECTIVE

To describe the capabilities and limitations of the current state of the art in pancreatic cancer diagnostics and to discuss recent progress in the development of novel, highly accurate molecular diagnostic approaches.

RESULTS

Molecular analyses currently under evaluation as novel diagnostic tests include detection of point mutations, genomic imbalances, aberrant methylation patterns and gene expression changes on the mRNA and protein levels in pancreatic juice, fine needle aspiration biopsies and brush cytologies.

CONCLUSIONS

In exploratory studies, several candidate molecular markers show great potential to serve as general indicators of malignancy, but need to be validated in large, controlled, prospective studies. Multiplexing of diagnostic tests, e.g. in the form of specialized DNA microarrays, may provide more differentiated diagnoses such as the distinction of various tumor types or prognostic information for individual patients. The MolDiag-Paca consortium is strongly engaged in advancing these developments on a European level.

A role for VICKZ proteins in the progression of colorectal carcinomas: regulating lamellipodia formation

VICKZ proteins are a highly conserved family of RNA binding proteins, implicated in RNA regulatory processes such as intracellular RNA localization, RNA stability, and translational control. During embryogenesis, VICKZ proteins are required for neural crest migration and in adults, the proteins are overexpressed primarily in different cancers. We hypothesized that VICKZ proteins may play a role in cancer cell migration. In patients, VICKZ expression varies with tumour type, with over 60% of colon, lung, and ovarian tumours showing strong expression. In colorectal carcinomas (CRCs), expression is detected at early stages, and the frequency and intensity of staining increase with progression of the disease to lymph node metastases, of which 97% express the protein at high levels. Indeed, in stage II CRC, the level of VICKZ expression in the primary lesion correlates with the degree of lymph node metastasis. In culture, VICKZ proteins rapidly accumulate in processes at the leading edge of PMA-stimulated SW480 CRC cells, where they co-localize with beta-actin mRNA. Two distinct cocktails of shRNAs, each targeting all three VICKZ paralogues, cause a dramatic drop in lamellipodia and ruffle formation in stimulated cells. Thus, VICKZ proteins help to facilitate the dynamic cell surface morphology required for cell motility. We propose that these proteins play an important role in CRC metastasis by shuttling requisite RNAs to the lamellipodia of migrating cells.

Oncofetal protein IMP3: a novel molecular marker that predicts metastasis of papillary and chromophobe renal cell carcinomas

BACKGROUND

Whether an oncofetal protein, IMP3, can serve as a prognostic biomarker to predict metastasis for patients with localized papillary and chromophobe subtypes of renal cell carcinomas (RCCs) was investigated.

METHODS

The expression of IMP3 in 334 patients with primary papillary and chromophobe RCC from multiple medical centers was evaluated by immunohistochemistry. The 317 patients with localized papillary and chromophobe RCCs were further evaluated for outcome analyses.

RESULTS

IMP3 was significantly increased in a subset of localized papillary and chromophobe RCCs that subsequently metastasized. Patients with localized IMP3-positive tumors (n=33; 10%) were over 10 times more likely to metastasize (risk ratio [RR], 11.38; 95% confidence interval [CI], 5.40-23.96; P<.001) and were nearly twice as likely to die (RR, 1.91; 95% CI, 1.13-3.22; P=.016) compared with patients with localized IMP3 negative tumors. The 5-year metastasis-free and overall survival rates were 64% and 58% for patients with IMP3-positive localized papillary and chromophobe RCCs compared with 98% and 85% for patients with IMP3 negative tumors, respectively. In multivariable analysis adjusting for the TNM stage and nuclear grade, patients with IMP3-positive tumors were still over 10 times more likely to progress to distant metastasis (RR, 13.45; 95% CI, 6.00-30.14; P<.001) and were still nearly twice as likely die (RR, 1.95; 95% CI, 1.15-3.31; P=.013) compared with patients with IMP3-negative tumors.

CONCLUSIONS

IMP3 is an independent prognostic biomarker that can be used to identify a subgroup of patients with localized papillary and chromophobe RCC who are at high risk for developing distant metastasis.

IMP-3 is a novel progression marker in malignant melanoma

Insulin-like growth factor-II messenger RNA (mRNA)-binding protein-3 (IMP-3), also known as K homology domain-containing protein overexpressed in cancer (KOC) and L523S, is a member of the insulin-like growth factor-II mRNA-binding protein family and is expressed during embryogenesis and in some malignancies. IMP-3 expression in melanocytic neoplasms has not been investigated. Fifty-six melanocytic neoplasms from 48 subjects were immunohistochemically studied using a monoclonal antibody against L523S/IMP-3. IMP-3 expression in melanoma was significantly higher than in Spitz nevi (P<0.05), and the staining intensity in the Spitz nevi was weak. IMP-3 expression in metastatic melanoma was significantly higher than in primary cutaneous melanoma with a Breslow depth </=1 mm (P<0.01). None of the benign nevi and dysplastic nevi expressed IMP-3. Our study demonstrates that IMP-3 is expressed in malignant melanoma but not in benign nevi, even when dysplastic features are present; IMP-3 is expressed in a significantly higher proportion of melanomas than Spitz nevi; and IMP-3 is expressed in metastatic melanomas significantly more than in thin melanomas. In conclusion, IMP-3 appears to be involved in the progression of malignant melanoma and may play an important role in the regulation of the biologic behavior of this tumor. Additionally, IMP-3 may have diagnostic utility in distinguishing melanoma from benign nevic cells, dysplastic nevi, and Spitz nevi.

NQO1 expression in pancreatic cancer and its potential use as a biomarker

Pancreatic ductal adenocarcinoma (PDA) is rarely curable due to regional/metastatic spread at diagnosis. Identification of molecular markers may enhance diagnosis and early detection of PDA. The 2-electron reductase, NAD(P)H:quinone oxidoreductase (NQO1) has been found to be overexpressed in many solid tumors including PDA, and may be a useful clinically relevant diagnostic marker of malignancy. For this study, we used 37 surgical resection cases: 24 PDAs and 13 benign pancreatic tissue specimens. An additional 16 specimens from pancreatic endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) were included as a pilot series. NQO1 was detected by avidin-biotin based immunohistochemical and immunocytochemical methods. Both staining intensity and proportion of NQO1 positive tumor cells were scored. Moderate to strong (2 to 3+) staining for NQO1 was detected in 22/24 (92%) surgically resected PDAs, 9/9 (100%) EUS-FNAs with malignant diagnoses, one cytologically atypical but not diagnostic for malignancy EUS-FNA, and 1/6 (17%) EUS-FNAs initially diagnosed as negative for malignancy. Subsequent histologic assessment confirmed malignancy in all 9 cytologically positive EUS-FNAs and in the atypical case. The NQO1 positive case initially diagnosed as negative for malignancy showed no evidence of carcinoma on subsequent tissue biopsy. NQO1 staining was also observed in some benign ducts/cells; however, correlation of NQO1 expression with cellular morphology assessment minimizes the risk of false positive diagnosis. NQO1 is consistently overexpressed in PDA. Although NQO1 is observed in some benign tissue components, this marker may be a clinically useful diagnostic adjunct for detection of PDA, independent of tumor grade/stage.

Expression of a novel oncofetal mRNA-binding protein IMP3 in endometrial carcinomas: diagnostic significance and clinicopathologic correlations

Insulin-like growth factor-II mRNA-binding protein 3 (IMP3) is a newly identified oncofetal mRNA-binding protein that is involved in embryogenesis and carcinogenesis of some malignant neoplasms. To investigate the diagnostic and clinicopathologic significance of this protein in endometrial carcinomas, we evaluated immunohistochemical expression of IMP3 in the two most common forms of endometrial malignancies, endometrioid adenocarcinoma and serous carcinoma. We selected 167 endometrial adenocarcinoma cases including 122 cases of endometrioid adenocarcinoma and 45 cases of serous carcinoma. Twenty samples of benign endometrium obtained from 20 patients with nonmalignant uterine lesions were used as controls. Positive immunohistochemical stain for IMP3 was identified in all serous carcinoma cases, among which, 39 (86%) and 3 (7%) cases showed IMP3 immunoreactivity in >50%, and 21-50, or 6-20% of tumor cells, respectively. Immunohistochemical reaction intensity for IMP3 was identified to be strong in 38 (84%) and intermediate in 7 (16%) cases of serous carcinoma. Fifty-four (44%) cases of endometrioid adenocarcinoma were negative for IMP3. Thirty (25%), 20 (16%), 10 (8%), and 8 (7%) cases of endometrioid adenocarcinoma demonstrated positive immunoreactivity for IMP3 in 1-5, 6-20, 21-50, and >50% of the tumor cells. Strong IMP3-staining intensity was noted in 34 (28%), intermediate in 26 (21%), and weak in 8 (7%) cases of endometrioid adenocarcinoma. All 20 control cases were negative for IMP3. To compare p53 with IMP3 expressions, we found that 35 (78%) of the serous carcinoma cases showed strong p53 immunohistochemical activity in >50% of the tumor cell nuclei. In contrast, 11 of 112 (10%) endometrioid adenocarcinoma cases demonstrated strong p53 positivity in >50% of the tumor cell nuclei. In conclusion, our findings demonstrate significant expression of IMP3 in serous carcinoma as compared to endometrioid adenocarcinoma (P<0.0001). Expression of IMP3 and p53 may be helpful biomarkers in the distinction of endometrial serous carcinoma from endometrioid adenocarcinoma. In addition, expression of IMP3 in endometrioid adenocarcinoma correlates with higher nuclear and architecture grades of the tumor (P=0.0000 and P=0.0002, respectively).

ZBP1 enhances cell polarity and reduces chemotaxis

The interaction of beta-actin mRNA with zipcode-binding protein 1 (ZBP1) is necessary for its localization to the lamellipod of fibroblasts and plays a crucial role in cell polarity and motility. Recently, we have shown that low ZBP1 levels correlate with tumor-cell invasion and metastasis. In order to establish a cause and effect relationship, we expressed ZBP1 in a metastatic rat mammary adenocarcinoma cell line (MTLn3) that has low endogenous ZBP1 levels and delocalized beta-actin mRNA. This leads to localization of beta-actin mRNA, and eventually reduces the chemotactic potential of the cells as well as their ability to move and orient towards vessels in tumors. To determine how ZBP1 leads to these two apparently contradictory aspects of cell behavior--increased cell motility but decreased chemotaxis--we examined cell motility in detail, both in cell culture and in vivo in tumors. We found that ZBP1 expression resulted in tumor cells with a stable polarized phenotype, and reduced their ability to move in response to a gradient in culture. To connect these results on cultured cells to the reduced metastatic ability of these cells, we used multiphoton imaging in vivo to examine tumor cell behavior in primary tumors. We found that ZBP1 expression actually reduced tumor cell motility and chemotaxis, presumably mediating their decreased metastatic potential by reducing their ability to respond to signals necessary for invasion.

Expression of oncofetal RNA-binding protein CRD-BP/IMP1 predicts clinical outcome in colon cancer

The oncofetal CRD-BP/IMP1 RNA binding protein regulates posttranscriptionally a handful of RNA transcripts, implicated in cell adhesion and invadopodia formation and was recently identified as a target of the beta-catenin/Tcf transcription factor that is constitutively activated in colorectal carcinomas (CRCs). The expression of CRD-BP/IMP1 was studied in normal adult intestines and CRCs. In normal mucosa, CRD-BP/IMP1 immunoreactivity was observed in few scattered cells located predominantly at or near the bottom of the crypts, whereas in CRCs the protein was detectable in tumor cells of 50% of the specimens analyzed. CRD-BP/IMP1 mRNA expression was measured by qRT-PCR in 78 CRCs. Thirty-two (41%) of the specimens were negative or had negligible expression, whereas the remaining forty-six (59%) expressed a wide range of CRD-BP/IMP1 mRNA levels. CRD-BP/IMP1 mRNA expression correlated with that of the putative stem/progenitor cell marker Musashi-1 mRNA (p = 0. 035). CRD-BP/IMP1 positive tumors metastasized and/or recurred more frequently (p = 0.001) and its expression defined a group of patients with shorter survival (p = 0.014). Furthermore, in a multivariate analysis CRD-BP/IMP1 expression was found to be an independent predictor of survival (p = 0.015). For stage I & II patients, the differences in metastasis/recurrence and survival rates remained significant (p = 0.001 and 0.033, respectively). These findings indicate that CRD-BP/IMP1 positive tumors exhibit early disease dissemination and unfavorable prognosis.

Extrapulmonary small cell carcinomas express K homology domain containing protein overexpressed in cancer, but carcinoid tumors do not

A number of malignancies, including high-grade neuroendocrine carcinomas of the lung, have been reported to express K homology domain containing protein overexpressed in cancer (KOC), a member of the insulin-like growth factor messenger RNA-binding protein (IMP) family also known as L523S and IMP3. KOC acts to promote tumor cell proliferation by enhancing insulin-like growth factor-II protein expression. This study aimed to examine KOC expression pattern in extrapulmonary neuroendocrine tumors. Seventy-five extrapulmonary neuroendocrine tumors that were surgically resected or had undergone biopsy, including 53 small cell carcinomas (uterine cervix, 21; bladder, 10; colorectum, 13; prostate, 7; stomach, 1; and esophagus, 1) and 22 carcinoid tumors (colorectum, 10; appendix, 5; ileum, 4; duodenum, 2; and stomach, 1), were immunohistochemically studied using a monoclonal antibody against KOC. Our results demonstrated that 47 small cell carcinomas (89%) showed moderate to strong positive staining for KOC, with 25 cases (53%) showing positivity in more than 90% of tumor cells and 22 cases (47%) in 40% to 80% of tumor cells. Three cases showed weak staining in 5% to 10% of the tumor cells. The remaining 3 cases (uterine cervix, 2; bladder, 1) showed completely negative immunoreactivity. No KOC immunostaining was detected in 22 carcinoid tumors. These findings indicate that KOC may play an important role in the regulation of biologic behavior of extrapulmonary small cell carcinomas. In addition, immunohistochemical detection of KOC expression may serve as a useful diagnostic tool in the distinction between small cell carcinoma and carcinoid tumor, particularly when the diagnostic material is a small biopsy with crushing artifact.

High-grade neuroendocrine carcinomas of the lung express K homology domain containing protein overexpressed in cancer but carcinoid tumors do not

K homology domain containing protein overexpressed in cancer (KOC) is a member of the insulin-like growth factor (IGF) messenger RNA-binding protein family and is expressed during embryogenesis and in certain malignancies. KOC, known as L523S and IGF messenger RNA-binding protein 3, was shown to be frequently expressed in high-grade neuroendocrine carcinomas of the lung in our immunohistochemical studies using a monoclonal antibody against human KOC. Specifically, all 10 small cell lung carcinomas (SCLCs) exhibited strong cytoplasmic staining, 9 with diffuse positivity and 1 with focal positivity. Among 14 large cell neuroendocrine carcinomas (LCNECs), 9 exhibited strong and diffuse cytoplasmic staining, and 5 cases showed focal immunoreactivity. In contrast, no KOC was detected in 21 typical and atypical carcinoids, except for one atypical carcinoid with oncocytic cells showing weak cytoplasmic staining. Although SCLCs exhibited a strong and diffuse staining pattern more frequently (90%) than LCNECs (64%), the difference did not reach statistical significance (P = .3408). Interestingly, our immunohistochemical studies demonstrated that IGF-II, reportedly regulated by KOC, was comparably expressed in SCLC, LCNEC, and typical and atypical carcinoids, irrespective of KOC expression status of the tumors. These results support the formulation that KOC may play an important role in the regulation of biologic behavior of high-grade neuroendocrine carcinomas. In addition, detection of KOC expression may be diagnostically useful in distinguishing high-grade neuroendocrine carcinomas from carcinoid tumors. Our findings of equivalent IGF-II expression in KOC-positive SCLC and LCNEC and KOC-negative carcinoid tumors suggest different regulatory mechanisms involved in the control of IGF-II expression in these tumors.

IMP3 is a novel biomarker for adenocarcinoma in situ of the uterine cervix: an immunohistochemical study in comparison with p16(INK4a) expression

Adenocarcinoma in situ of the uterine cervix remains a diagnostic challenge in a small proportion of cases. This suggests a need for biomarker that may be of help in establishing the diagnosis. The aim of this study was to evaluate the potential of insulin-like growth factor-II mRNA-binding protein 3 and cyclin-dependent kinase inhibitor p16(INK4a) as biomarkers for adenocarcinoma in situ. Forty-four samples of adenocarcinoma in situ from 40 patients and 23 control cases of benign uterine cervix were included in this study. In addition to benign endocervical epithelium, 19 of these 23 control cases also showed focal tubal metaplasia. Cytoplasmic immunoreactivity for insulin-like growth factor-II mRNA-binding protein 3 was identified in 41 (93%) adenocarcinoma in situ samples, among which, 29 (71%), 10 (24%), and 2 (5%) samples showed insulin-like growth factor-II mRNA-binding protein 3 positive staining in 50% or more, >5 to <50 and <5% of adenocarcinoma in situ lesional cells, respectively. Immunohistochemical reaction intensity for insulin-like growth factor-II mRNA-binding protein 3 was found to be strong in 34 adenocarcinoma in situ samples, intermediate in five, and weak in two. All 23 control cases were negative for insulin-like growth factor-II mRNA-binding protein 3. p16(INK4a) expression was identified in all of the adenocarcinoma in situ samples with intermediate staining intensity seen in seven samples and strong in the remainder. Fourteen of 19 (74%) tubal metaplasia cases showed p16(INK4a) immunoreactivity in >50% of the tubal metaplastic epithelium with staining intensity ranging from weak to strong. Our findings demonstrate significant expression of insulin-like growth factor-II mRNA-binding protein 3 and p16(INK4a) in adenocarcinoma in situ as compared to benign endocervical glands, suggesting that expression of these biomarkers may be helpful in the distinction of adenocarcinoma in situ from benign endocervical glands, particularly in difficult borderline cases.

Analysis of RNA-binding protein IMP3 to predict metastasis and prognosis of renal-cell carcinoma: a retrospective study

BACKGROUND

Distant metastasis is the main cause of death from renal-cell carcinoma, and the metastatic potential of tumours is often unpredictable. We aimed to investigate whether IMP3, an oncofetal RNA-binding protein, can be used as a biomarker to predict metastasis and prognosis of renal-cell carcinoma.

METHODS

We studied 501 primary and metastatic renal-cell tumours. 371 patients with localised primary tumours were further investigated by use of survival analysis. We assessed IMP3 expression in tumour tissues by immunohistochemistry, and IMP3 mRNA and protein expression in selected tissues by quantitative real-time PCR and western blot analysis.

FINDINGS

Compared with non-metastatic renal-cell tumours, IMP3 expression was greatly increased not only in metastatic tumours but also in a subset of primary tumours that were likely to subsequently develop metastases. Patients with primary localised tumours that did not express IMP3 had a longer metastasis-free survival and overall survival than did those with tumours expressing IMP3 (p<0.0001). Patients with IMP3-positive localised tumours had a much lower 5-year metastasis-free survival than did those with IMP3-negative tumours (for stage I tumours, 44% vs 98%, hazard ratio 17.18 [95% CI 7.82-37.78]; stage II, 41% vs 94%, 10.14 [3.46-29.68]; stage III, 16% vs 62%, 4.04 [2.23-7.31]). IMP3 expression was also associated with reduced 5-year overall survival (stage I, 32% vs 89%, 6.44 [3.63-11.42]; stage II, 41% vs 88%, 6.93 [2.63-18.27]; stage III, 14% vs 58%, 3.46 [1.98-6.05]). Multivariable analysis of IMP3 status (positive vs negative) in primary tumours showed hazard ratios of 5.84 (95% CI 3.60-9.49) for metastasis-free survival and 4.01 (2.66-6.05) for overall survival (both p<0.0001), which were much higher than hazard ratios associated with other independent risk factors.

INTERPRETATION

IMP3 is an independent prognostic marker that can be used at initial diagnosis of renal-cell carcinoma to identify patients who have a high potential to develop metastasis and who might benefit from early systemic treatment.

The RNA-binding protein, Vg1RBP, is required for pancreatic fate specification

Signaling mechanisms underlying the induction of the pre-pancreatic tissue within the endoderm remain poorly understood. Through an expression cloning strategy, we have identified a previously uncharacterized pancreatic factor that we named Shirin. Interestingly, the non-coding RNA regulatory sequence (3 UTR) of Shirin is sufficient to induce insulin expression in Xenopus embryos. Biochemical studies demonstrate that this RNA sequence is able to bind directly to a trans-acting factor, Vg1RBP, which was previously shown to be involved in the localization of endodermal determinant factors. Loss-of-function analysis indicates that Vg1RBP is required for establishment of pancreatic fate within the endoderm, suggesting a synergism between Vg1RBP and Shirin in the embryo. This study argues for a central role of post-transcriptional mechanisms in establishing pancreatic fate, where a 3 UTR may recruit factors necessary for pancreatic development, and highlights an unknown embryological activity of Vg1RBP.