Expression of RNA-binding protein IMP3 (KOC) in benign urothelium and urothelial tumors

Prognostic value of IMP3 immunohistochemical expression in triple negative breast cancer

Triple negative breast cancer (TNBC) account for 12% to 17% of all breast cancers. It is a heterogeneous group of tumors associated with aggressive clinical course. Insulin-like growth factor II mRNA binding protein 3 (IMP3) belongs to a family of insulin-like growth factor type II (IGF2), which plays a key role in the transmission and stabilization of mRNA, cell growth, and migration during embryogenesis. Increased expression of IMP3 is associated with aggressive behavior of different tumor types, advanced clinical stage, distant metastasis, and shorter overall survival (OS).The study included 118 patients with breast carcinoma diagnosed as TNBC and immunohistochemical staining for estrogen receptors (ER), progesterone receptors (PR), epidermal growth factor receptor 2 (HER2/neu), Ki-67, and IMP3 was performed. Correlations between categorical variables were studied using the chi-square and the Mann-Whitney U test. For survival analysis, the Kaplan-Meier method, log-rank test and the Cox proportional hazard regression model were used.Positive expression of IMP3 protein was present in 35.6% of TNBC. The presence of basal morphology was observed in 46.6% of TNBC. Positive IMP3 expression was connected with larger size of tumor, higher clinical stage, and basal morphology (P = .039, P = .034, P < .001). Disease-free survival and OS were significantly shorter in IMP3 positive TNBC.According to results of our study IMP3 expression can be used as negative prognostic factor for triple negative breast carcinomas. Targeting IMP3 molecule could be an effective approach to the management of a triple negative breast cancer with new immunological therapies, which does not yet exist for this group of tumors.

Insulin-like growth factor-II mRNA binding protein-3 and podoplanin expression are associated with bone invasion and prognosis in oral squamous cell carcinoma

OBJECTIVE

This study aimed to evaluate the prognostic implications of insulin-like growth factor-II mRNA binding protein-3 (IMP3) and podoplanin (PDPN) as therapeutic targets against oral squamous cell carcinoma (OSCC) with bone invasion.

STUDY DESIGN

We elucidated the correlation of IMP3 and PDPN expression with bone invasion in 160 OSCC tissue specimens, and assessed a mouse calvarium xenograft model using an IMP3- and PDPN-depleted OSCC cell line.

RESULTS

The retrospective analysis revealed that the expression of IMP3 and PDPN is significantly correlated with T stage, lymph node metastasis, and the overall survival of OSCC patients. In addition, the dual expression of IMP3 and PDPN but not the single expression of either IMP3 or PDPN was associated with bone invasion and the number of osteoclasts in patients with OSCC. In support of these findings, IMP3 or PDPN depletion inhibited the invasive capacity of OSCC cells in a three-dimensional culture system, tumorigenesis, and regional bone destruction in a xenograft mouse model. In addition, IMP3 or PDPN depletion inhibited the expression of interleukin (IL)-6 and IL-8 in OSCC cells, and decreased the expression of receptor activator of NF-κB ligand (RANKL) in xenograft tumor tissues of OSCC.

CONCLUSIONS

These results suggest that IMP3 and PDPN may have strong influence on the pathogenesis of OSCC, especially in bone invasion, and may serve as novel therapeutic targets with prognostic implications for bone-invasive OSCC.

IMP3 Is Strongly Expressed in Malignant Phyllodes Tumors of the Breast

Background. Phyllodes tumors (PTs) of the breast are rare biphasic neoplasms and are classified as benign, borderline, or malignant. Many biological markers have been studied to discriminate between different grades of PTs. IMP3 is a member of the insulin-like growth factor II mRNA binding protein (IMP) family and is expressed in developing tissues during embryogenesis, whereas in adult tissues it is found only at low or undetectable levels. IMP3 is considered a marker of biological aggressiveness in many cancers, including breast and lung. The aim of this study was to evaluate the immunohistochemical expression of IMP3 in a series of PTs and to determine its association with histological grade and clinical outcome. Materials and Methods. We reviewed retrospectively 62 cases of PTs including their recurrences and 20 cases of fibroadenoma. PTs have been classified as benign in 40 cases, borderline in 13 cases, and malignant in 9 cases. Results. There were significant differences in IMP3 expression: in malignant PTs IMP3 expression was higher (56% of cases) than in borderline (15%) and benign cases (5%), ( P = .001). Fibroadenoma showed no expression for IMP3. IMP3 expression was different in cases with recurrence than cases without recurrence. Furthermore, 3 of the recurrences had a higher histological grade with a positive IMP3 expression compared with the primary tumor. Conclusions. This is the first study evaluating the IMP3 immunohistochemical expression in PTs. Its expression correlates with histological grade and could be used in the differential diagnosis of fibroepithelial tumors and in predicting a more aggressive behavior.

The role of the oncofetal IGF2 mRNA-binding protein 3 (IGF2BP3) in cancer

The post-transcriptional control of gene expression mediated by RNA-binding proteins (RBPs), long non-coding RNAs (lncRNAs) as well as miRNAs is essential to determine tumor cell fate and thus is a major determinant in cancerogenesis. The IGF2 mRNA binding protein family (IGF2BPs) comprises three RBPs. Two members of the family, IGF2BP1 and IGF2BP3, are bona fide oncofetal proteins, which are de novo synthesized in various human cancers. In vitro studies revealed that IGF2BPs serve as post-transcriptional fine-tuners modulating the expression of genes implicated in the control of tumor cell proliferation, survival, chemo-resistance and metastasis. Consistently, the expression of both IGF2BP family members was reported to correlate with an overall poor prognosis and metastasis in various human cancers. Due to the fact that most reports used a pan-IGF2BP antibody for studying IGF2BP expression in cancer, paralogue-specific functions can barely be evaluated at present. Nonetheless, the accordance of IGF2BPs' role in promoting an aggressive phenotype of tumor-derived cells in vitro and their upregulated expression in aggressive malignancies provides strong evidence that IGF2BPs are powerful post-transcriptional oncogenes enhancing tumor growth, drug-resistance and metastasis. This suggests IGF2BPs as powerful biomarkers and candidate targets for cancer therapy.

IMP3, a Promising Prognostic Marker in Clear Cell Renal Cell Carcinoma

Background

Insulin-like growth factor II mRNA-binding protein 3 (IMP3) has been reported as a prognostic biomarker in various cancers. To validate IMP3 as a prognostic biomarker in renal cell carcinoma (RCC), we investigated the expression of IMP3, p53, and Ki-67, and their associations with clinicopathologic outcomes.

Methods

We studied 148 clear cell RCCs (CCRCCs) from patients who underwent radical nephrectomy. The expression levels of IMP3, p53, and Ki-67 were assessed by immunohistochemical staining and the clinical and pathologic parameters were retrospectively reviewed.

Results

Twenty-nine percent of CCRCCs expressed IMP3. Forty-one percent of IMP3-immunopositive tumors developed metastases, while only 11.4% of IMP3-negative tumors developed metastases (p<.001). A Kaplan-Meier curve showed that patients with IMP3-immunopositive tumors had lower metastasis-free survival and cancer-specific survival than did those with IMP3-immunonegative tumors (p<.001 and p<.001, respectively). Expression of high Ki-67 proliferation index was also associated with a higher metastatic rate. In the multivariate Cox regression analysis, pT stage and IMP3-positivity were independently associated with disease-specific survival.

Conclusions

IMP3 is an independent prognostic biomarker for patients with CCRCC to predict metastasis and poor outcome.

Insulin-like growth factor 2 mRNA-binding proteins (IGF2BPs): post-transcriptional drivers of cancer progression?

The insulin-like growth factor-2 mRNA-binding proteins 1, 2, and 3 (IGF2BP1, IGF2BP2, IGF2BP3) belong to a conserved family of RNA-binding, oncofetal proteins. Several studies have shown that these proteins act in various important aspects of cell function, such as cell polarization, migration, morphology, metabolism, proliferation and differentiation. In this review, we discuss the IGF2BP family’s role in cancer biology and how this correlates with their proposed functions during embryogenesis. IGF2BPs are mainly expressed in the embryo, in contrast with comparatively lower or negotiable levels in adult tissues. IGF2BP1 and IGF2BP3 have been found to be re-expressed in several aggressive cancer types. Control of IGF2BPs’ expression is not well understood; however, let-7 microRNAs, β-catenin (CTNNB1) and MYC have been proposed to be involved in their regulation. In contrast to many other RNA-binding proteins, IGF2BPs are almost exclusively observed in the cytoplasm where they associate with target mRNAs in cytoplasmic ribonucleoprotein complexes (mRNPs). During development, IGF2BPs are required for proper nerve cell migration and morphological development, presumably involving the control of cytoskeletal remodeling and dynamics, respectively. Likewise, IGF2BPs modulate cell polarization, adhesion and migration in tumor-derived cells. Moreover, they are highly associated with cancer metastasis and the expression of oncogenic factors (KRAS, MYC and MDR1). However, a pro-metastatic role of IGF2BPs remains controversial due to the lack of ‘classical’ in vivo studies. Nonetheless, IGF2BPs could provide valuable targets in cancer treatment with many of their in vivo roles to be fully elucidated.

Functional invadopodia formation through stabilization of the PDPN transcript by IMP-3 and cancer-stromal crosstalk for PDPN expression

We previously reported that insulin-like growth factor-II mRNA-binding protein-3 (IMP-3) depletion (IMP-3(Δ)) was shown to inhibit invadopodia formation and extracellular matrix degradation capacity in oral squamous cell carcinoma (OSCC) cells. In this study, we found that IMP-3(Δ) cells significantly downregulated the podoplanin (PDPN) level, which resulted in a loss of extracellular matrix degradation activity, although invadopodia was still thriving. From RNA in situ hybridization using a digoxigenin-labeled 3'UTR recognition probe of PDPN and reporter assay with 3'UTR of the PDPN gene cloned downstream from the luciferase reporter gene, we revealed that IMP-3 depletion was shown to be downregulated, which most probably lowered PDPN gene expression by reducing mRNA stabilization. In a xenograft model, PDPN depletion was the cause of a decrease in tumor volume and regional infiltration into nearby stroma. Taken together, transforming growth factor beta 1 increased PDPN expression, which potentiated cancer invasion through increased invadopodia formation and extracellular matrix degradation in the low invasive OSCC cell line. Reciprocally, interleukin-1 beta secreted by OSCC cells, stimulated transforming growth factor beta 1 secretion from stromal fibroblasts to induce PDPN expression in OSCC cells. In addition, a retrospective investigation of OSCC patients found that IMP-3 and PDPN expression significantly correlated with lymph node metastasis of OSCC patients. Moreover, co-expression of IMP-3 and PDPN were frequently detected both in primary and lymph nodes metastatic OSCC cells using immunohistochemical dual staining. Thus, the IMP-3-PDPN axis may be a sensitive target molecule in anti-invadopodia therapy for the treatment of metastatic cancers.

Expression of insulin-like growth factor II mRNA-binding protein 3 in human esophageal adenocarcinoma and its precursor lesions

CONTEXT

Insulin-like growth factor II mRNA-binding protein 3 (IMP3) is an oncofetal protein highly expressed in fetal tissue and malignant tumors but only rarely within adult benign tissues. The expression of IMP3 in esophageal adenocarcinoma (EAC) and its precursor lesions including distinctive type Barrett mucosa (BM, intestinal metaplasia) and esophageal columnar dysplasia (ECD) is largely unknown.

OBJECTIVE

To characterize the patterns of IMP3 expression in EAC and its precursor lesions.

DESIGN

Samples from 132 cases of EAC, 28 cases of ECD (16 high-grade dysplasia and 12 low-grade dysplasia cases), 28 cases of BM without dysplasia, and 138 cases of nonneoplastic esophageal mucosa without dysplasia or BM within formalin-fixed, paraffin-embedded tissue microarray blocks were examined. Tissues were stained with mouse monoclonal anti-IMP3 antibody. The intensity (1-3+) and percent (0%-100%) of positive cytoplasmic and/or membranous IMP3 staining cells were determined.

RESULTS

Most of EAC cases (93 of 132; 70%) showed cytoplasmic and membranous IMP3 staining. Poorly and moderately differentiated EAC showed statistically significant higher IMP3 expression compared with well-differentiated EAC (P < .001). A subset of ECD cases (7 of 28; 25%) was positive for IMP3, including 3 low-grade dysplasia cases (focal 1+ IMP3 staining) and 4 high-grade dysplasia cases (more diffuse 1-2+ IMP3 staining). No IMP3 staining was observed in any nonneoplastic esophageal mucosa and BM tissues without dysplasia.

CONCLUSIONS

This study suggests that IMP3 may play a role in the carcinogenesis of EAC and has diagnostic utility in differentiating neoplastic and nonneoplastic lesions of the esophagus.

Significance of molecular markers in survival prediction of oral squamous cell carcinoma

BACKGROUND

An accurate system for predicting the survival of patients with oral squamous cell carcinoma (OSCC) will be useful for deciding appropriate therapies. The prediction accuracy of prediction models can be improved by using molecular biomarkers. We constructed a nomogram for predicting the survival of patients with OSCC using clinical variables and molecular markers.

METHODS

Protein 53 (p53), insulin-like growth factor II mRNA-binding protein 3 (IMP3), cyclooxygenase 2 (COX2), and HuR were localized immunohistochemistry in 96 patients with primary OSCC who underwent surgical resection between January 1994 and June 2003 at the Yonsei Dental Hospital in Seoul, Korea.

RESULTS

On univariate and multivariate analysis, the expression of IMP3 was significantly associated with the risk of death. P53 was also significantly associated with survival of OSCC in the case of negative IMP3 and the prediction accuracy was improved by including these 2 factors in the prediction model.

CONCLUSION

Survival in OSCC can be predicted more accurately by using biomarkers. The constructed nomogram predicted survival after treatment for an individual patient with OSCC, and it can be practically used as a tool to help decide which adjuvant treatment is most appropriate.

Insulin-like growth factor II mRNA-binding protein 3: a novel prognostic biomarker for oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is caused by multiple factors, including carcinogen exposure. Insulin-like growth factor II mRNA-binding protein 3 (IMP3) is highly expressed in various cancer cells but is rarely expressed in normal cells. We investigated whether IMP3 can be used as a prognostic biomarker for OSCC.

METHODS

We performed immunohistochemistry and Western blotting to examine IMP3 expression in human tissues. We also investigated correlations among IMP3 expression, clinicopathologic factors, and overall survival.

RESULTS

IMP3 was overexpressed in OSCC cells. The expression was correlated with high histologic grade, lymph node metastasis, and advanced tumor and clinical stages. Univariate analysis indicated that advanced clinical stages, lymph node metastases, and IMP3 expression were predictive factors for OSCC. Multivariate analysis showed that IMP3 expression was an independent prognostic indicator for OSCC.

CONCLUSIONS

IMP3 expression was related to various clinicopathologic factors. IMP3 expression was an independent prognostic factor in patients with OSCC.

Insulin growth factor-2 binding protein 3 (IGF2BP3) is a glioblastoma-specific marker that activates phosphatidylinositol 3-kinase/mitogen-activated protein kinase (PI3K/MAPK) pathways by modulating IGF-2

Glioblastoma is the most common and malignant form of primary astrocytoma. Upon investigation of the insulin-like growth factor (IGF) pathway, we found the IGF2BP3/IMP3 transcript and protein to be up-regulated in GBMs but not in lower grade astrocytomas (p < 0.0001). IMP3 is an RNA binding protein known to bind to the 5′-untranslated region of IGF-2 mRNA, thereby activating its translation. Overexpression- and knockdown-based studies establish a role for IMP3 in promoting proliferation, anchorage-independent growth, invasion, and chemoresistance. IMP3 overexpressing B16F10 cells also showed increased tumor growth, angiogenesis, and metastasis, resulting in poor survival in a mouse model. Additionally, the infiltrating front, perivascular, and subpial regions in a majority of the GBMs stained positive for IMP3. Furthermore, two different murine glioma models were used to substantiate the above findings. In agreement with the translation activation functions of IMP3, we also found increased IGF-2 protein in the GBM tumor samples without a corresponding increase in its transcript levels. Also, in vitro IMP3 overexpression/knockdown modulated the IGF-2 protein levels without altering its transcript levels. Additionally, IGF-2 neutralization and supplementation studies established that the proproliferative effects of IMP3 were indeed mediated through IGF-2. Concordantly, PI3K and MAPK, the downstream effectors of IGF-2, are activated by IMP3 and are found to be essential for IMP3-induced cell proliferation. Thus, we have identified IMP3 as a GBM-specific proproliferative and proinvasive marker acting through IGF-2 resulting in the activation of oncogenic PI3K and MAPK pathways.

Clinical utility of immunohistochemistry in the diagnoses of urinary bladder neoplasia

Urothelial carcinomas demonstrate diverse morphologic and immunologic features that frequently lead to diagnostic challenges. Recent advances have identified a number of immunohistochemical stains that, when used in the context of a panel, can be a valuable tool in properly classifying primary urothelial carcinoma and carcinomas secondarily involving the urinary bladder. In addition, new biomarkers prove helpful in the staging of bladder carcinoma. In this article, we review the clinical utility of immunohistochemistry in a series of diagnostic scenarios, including flat urothelial lesions with atypia, rare variants of urothelial carcinoma, primary adenocarcinoma versus secondary colorectal tumors, distinguishing prostate from urothelial carcinoma, and the utility of smoothelin in staging bladder carcinoma. Emphasis is placed on panels of commonly used biomarkers to establish diagnoses.

Diagnostic utility of IMP3 expression in thyroid neoplasms: a quantitative RT-PCR study

The capability of molecular markers to differentiate between benign and malignant well-differentiated thyroid tumors remains unclear. The aim of this study was to evaluate the use of insulin-like growth factor II mRNA binding protein-3 (IMP3) mRNA expression to distinguish benign from malignant thyroid tumors. RNA samples from 80 formalin-fixed, paraffin-embedded thyroid tissues, including 22 usual papillary thyroid carcinomas (PTCs), 18 follicular variants of PTC, 5 follicular thyroid carcinomas, 33 follicular adenomas, and 2 hyperplastic nodules, were used for quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis. IMP3 mRNA expression levels in thyroid tumors were expressed as relative fold change (fold) after normalization with normal thyroid RNA. The results showed that thyroid carcinomas including PTC, follicular variants of PTC, and follicular thyroid carcinomas have significantly higher IMP3 expression levels with 48.3, 35.3, and 43.8 fold, respectively, compared with benign thyroid lesions (2.8 fold). Using the IMP3 expression value of 5 fold as a cutoff point to separate benign and malignant thyroid tumors, IMP3 qRT-PCR analysis had a 91.4% clinical specificity and 86.7% clinical sensitivity for the diagnosis of well-differentiated thyroid carcinomas. Conventional RT-PCR and immunohistochemical analysis for IMP3 in a subset of cases supported the qRT-PCR results. These results indicate that detection of IMP3 mRNA expression levels by qRT-PCR may be a useful molecular marker to assist in the diagnosis of well-differentiated thyroid carcinomas.

Insulin-like growth factor II mRNA binding protein 3 (IMP3) is overexpressed in prostate cancer and correlates with higher Gleason scores

Background

The oncofetal protein insulin-like growth factor II mRNA binding protein 3 (IMP3) is an important factor for cell-migration and adhesion in malignancies. Recent studies have shown a remarkable overexpression of IMP3 in different human malignant neoplasms and also revealed it as an important prognostic marker in some tumor entities. To our knowledge, IMP3 expression has not been investigated in prostate carcinomas so far.

Methods

Immunohistochemical stainings for IMP3 were performed on tissue microarray (TMA) organized samples from 507 patients: 31 normal prostate tissues, 425 primary carcinomas and 51 prostate cancer metastases or castration-resistant prostate cancers (CRPC). IMP3 immunoreactivity was semiquantitatively scored and correlated with clinical-pathologic parameters including survival.

Results

IMP3 is significantly stronger expressed in prostate carcinomas compared to normal prostate tissues (p < 0.0001), but did not show significant correlation with the pT-stage, the proliferation index (MIB1), preoperative serum PSA level and the margin status. Only a weak and slightly significant correlation was found with the Gleason score and IMP3 expression failed to show prognostic significance in clinico-pathological correlation-analyses.

Conclusions

Although IMP3 is overexpressed in a significant proportion of prostate cancer cases, which might be of importance for novel therapeutic approaches, it does not appear to possess any immediate diagnostic or prognostic value, limiting its potential as a tissue biomarker for prostate cancer. These results might be corroborated by the fact, that two independent tumor cohorts were separately reviewed.

IMP3 is a novel prognostic marker that correlates with colon cancer progression and pathogenesis

BACKGROUND

Insulin-like growth factor-II mRNA-binding protein 3 (IMP3) plays a vital role in carcinogenesis; however, its significance and prognostic value in colon cancer remain unclear.

METHODS

In this study, a tissue microarray (TMA) containing 203 samples of primary colon cancer was assessed for IMP3 expression by immunohistochemistry. The TMA included 66 lymph node metastasis (LNM) samples. The mRNA and protein expression levels of IMP3 were evaluated by reverse transcription-PCR and Western blot analysis, respectively.

RESULTS

Cytoplasmic immunoreactivity of IMP3 was significantly higher in LNM (93%) than in primary colon cancer (65%) or normal mucosa (3.9%). Increased IMP3 levels were significantly correlated with higher clinical stage, T classification, LNM, presence of distant metastasis, and Ki-67 positivity. IMP3 was up-regulated in colon cancer compared with paired normal colonic mucosa. IMP3 expression was associated with an 11-fold increased risk of distant metastases (hazard ratio (HR) 10.7; 95% confidence interval (CI) 3.3-34.5; P < 0.0001). Patients with IMP3-positive localized tumors had lower 5-year disease-free survival (DFS) (HR 2.87; 95% CI 1.65-4.98; P < 0.0001) and overall survival (OS) (HR 4.2; 95% CI 2.51-10.17; P < 0.0001) than those with IMP3-negative tumors. Multivariate survival analysis showed that IMP3 was an independent prognostic marker for DFS (HR 1.92; 95% CI 1.06-3.47; P = 0.03) and OS (HR 2.37; 95% CI 1.2-4.7; P = 0.014).

CONCLUSIONS

IMP3 may play an important role in colon cancer progression and could serve as a prognostic biomarker to identify patients at risk of developing metastasis or recurrence after colonectomy.

Analysis of IMP3 expression in normal and neoplastic human pituitary tissues

Insulin-like growth factor II mRNA-binding protein 3 (IMP3) is an oncofetal protein highly expressed in fetal tissue and malignant tumors but rarely found in adult benign tissues. In various tumors, IMP3 expression is correlated with increased tumor aggressiveness and reduced overall survival. To our knowledge, IMP3 expression has not been investigated in pituitary tumors. We analyzed the immunohistochemical expression of IMP3 in five normal pituitary tissues and 75 pituitary tumors (64 adenomas and 11 carcinomas) to determine if specific tumor types expressed IMP3 and if there were differences in IMP3 expression between adenomas and carcinomas. Immunohistochemical analysis showed that IMP3 was positive in four (80%) normal pituitaries with focal stain in a subset of normal anterior pituitary cells. IMP3 was expressed in 31% (20/64) of adenomas and in 36% (4/11) of carcinomas. A slightly higher level of IMP3 expression was observed in PRL-GH-TSH adenomas compared to the other types of pituitary adenomas. Expression of IMP3 was not significantly higher in carcinomas than in adenomas (p = 0.737). RT-PCR and Western Blotting supported the heterogeneous expression of IMP3. These results indicate that IMP3 is expressed both in normal and in neoplastic pituitary gland tissues without significant differences in expression levels in pituitary carcinomas.

IMP-3 is differentially expressed in normal and neoplastic lymphoid tissue

IMP-3 is a member of the insulin-like growth factor II mRNA binding protein (IMP) family of proteins that play a role in RNA trafficking and stabilization and cell growth and migration during embryogenesis but which are down-regulated in adult tissue. However, IMP-3 has recently been shown to be overexpressed in several epithelial malignancies, with increased expression correlating with aggressive behavior. To our knowledge, there is no published literature evaluating IMP-3 in lymphoid tissue. Accordingly, we immunohistochemically evaluated IMP-3 expression in normal lymphoid tissue and 141 lymphoid neoplasms. Physiologically, IMP-3 expression was restricted to germinal center B cells. Among lymphoid neoplasms, Hodgkin lymphoma demonstrated the highest percentage of positive cases (26/26, 100%) often with bright staining. Burkitt lymphoma was positive in 10 (83%) of 12 cases with moderate to bright staining. Although follicular lymphoma was also positive in a high percentage of cases (12/15, 80%), the intensity was exclusively weak to moderate. Although 22 (85%) of 26 of diffuse large B-cell lymphomas were positive for IMP-3, there was wide variability in staining intensity, which did not correlate with classification into activated B cell versus germinal center B origin. By contrast, lower proportions (8%-20%) of other non-germinal center B lymphoma subtypes were IMP-3-positive. In conclusion, although IMP-3 expression is seemingly restricted to physiologic germinal center B cells, its expression in lymphomas of germinal center B origin is less robust. However, there does appear to be some association with the latter group of lymphomas, which may prove to have diagnostic or therapeutic relevance as the biologic role of IMP-3 is further elucidated.

Molecular and cytogenetic insights into the pathogenesis, classification, differential diagnosis, and prognosis of renal epithelial neoplasms

Renal cell carcinomas comprise a heterogeneous group of epithelial neoplasms with diverse biologic potential and variable clinical outcomes. The application of molecular and cytogenetic techniques to the study of renal neoplasms has improved our understanding of the molecular mechanisms responsible for tumor initiation and progression. Molecular classification of renal cell carcinomas has also provided new avenues for diagnosis, clinical outcome, and therapy response prediction. In this article, we review the molecular markers for various renal epithelial neoplasms and discuss the mechanisms underlying the development of these neoplasms. We also evaluate the use of molecular and cytogenetic techniques in establishing an accurate diagnosis in difficult cases and their potential usefulness in accurately classifying renal neoplasms, assessing prognosis, and selecting appropriate therapy.