Immunostaining characteristics of irisin in benign and malignant renal cancers

ABSTRACT

We investigated the expression of irisin in renal cancers using immunocytochemistry. Irisin has been reported to exhibit anticancer properties. The study groups consisted of 22 cases each of control renal tissue, oncocytoma, chromophobe renal cell carcinoma (RCC), clear cell RCC (Fuhrman nuclear grades 1, 2, 3 and 4) and papillary RCC. We evaluated 10 slides for each of 176 cases. Slides were immunostained for irisin and histoscores were calculated for the prevalence and strength of immunostaining. Fuhrman nuclear grade 1, 2, 3 clear cell RCC and papillary RCC exhibited no irisin immunoreactivity. Irisin immunoreactivity was observed in some Fuhrman nuclear grade 4 RCCs. We found a significant decrease in irisin staining in chromophobe RCC compared to the control. Immunoreactivity in the oncocytoma tissue was comparable to the control group. Irisin immunoreactivity in chromophobe RCC decreased and no immunoreactivity was observed in Fuhrman nuclear grade 1, 2, 3 clear cell RCC and papillary RCC. Immunistochemical screening of irisin in renal oncocytomas and renal cancers may be useful for differential diagnosis.     

Critical role of TRPC6 channels in the development of human renal cell carcinoma

Renal cell carcinoma (RCC) is the most common tumor arising from the cells in the lining of tubules in the kidney. Some members of the Ca²⁺-permeable transient receptor potential canonical (TRPC) family of channel proteins have demonstrated a role in the proliferation of some types of cancer cells. In this study, we investigated the role of TRPC6 in the development of human RCC. RT-PCR and Western blotting were used to investigate TRPC6 expression in 1932 and ACHN cells. Immunohistochemical techniques were applied to study TRPC6 expression in 60 cases of RCC primary tissue samples and 10 cases of corresponding normal renal tissues. To inhibit TRPC6 activity or expression, RNA interference was used. The effects of TRPC6 channels on RCC cell viability and cell cycle progression were investigated by MTT and flow cytometry. TRPC6 was expressed in 1932 and ACHN cells. TRPC6 protein was detected in 73.3 % of RCC samples, and there was a significant difference compared with the normal renal samples (30 %) (p < 0.05). Moreover the level of TRPC6 expression was associated with RCC Fuhrman grade (p < 0.01). Blockade of TRPC6 channels in ACHN cells suppressed basal cell proliferation and partially inhibited HGF-induced cell proliferation. Furthermore, inhibition of TRPC6 channels expression prolonged the transition through G₂/M phase in ACHN cells. In summary, expression of TRPC6 is markedly increased in RCC specimens and associated with RCC histological grade. TRPC6 plays an important role in ACHN cells proliferation.     

肾细胞癌淋巴结转移预测指标的Logistic回归分析

目的：研究肾细胞癌淋巴结转移的危险因素,并建立Logistic回归模型。方法：2002年2月-2010年10月我院手术治疗的肾细胞癌163例,对其临床病理资料进行单因素和多因素的Logistic回归分析。结果：淋巴结转移的发生率为20．9％（34／163）。单因素分析显示：肿瘤大小、临床分期、Fuhrman核分级和贫血与肾细胞癌淋巴结转移的风险有关（P〈0．05）;多因素分析显示：肿瘤大小、临床分期和Fuhrman核分级是RCC淋巴结转移独立的风险因素。结论：肾细胞癌淋巴结转移的风险与肿瘤大小、临床分期和Fuhrman核分级有关,Logistic回归模型对于判断预后、指导术后治疗及随访方案的制订具有重要作用。     

Cytoplasmic Accumulation of Heterogeneous Nuclear Ribonucleoprotein K Strongly Promotes Tumor Invasion in Renal Cell Carcinoma Cells

Heterogeneous nuclear ribonucleoprotein (hnRNP) K is a part of the ribonucleoprotein complex which regulates diverse biological events. While overexpression of hnRNP K has been shown to be related to tumorigenesis in several cancers, both the expression patterns and biological mechanisms of hnRNP K in renal cell carcinoma (RCC) cells remain unclear. In this study, we showed that hnRNP K protein was strongly expressed in selected RCC cell lines (ACHN, A498, Caki-1, 786–0), and knock-down of hnRNP K expression by siRNA induced cell growth inhibition and apoptosis. Based on immunohistochemical (IHC) analysis of hnRNP K expression in human clear cell RCC specimens, we demonstrated that there was a significant positive correlation between hnRNP K staining score and tumor aggressiveness (e.g., Fuhrman grade, metastasis). Particularly, the rate of cytoplasmic localization of hnRNP K in primary RCC with distant metastasis was significantly higher than that in RCC without metastasis. Additionally, our results indicated that the cytoplasmic distribution of hnRNP K induced by TGF-β stimulus mainly contributed to TGF-β-triggered tumor cell invasion in RCC cells. Dominant cytoplasmic expression of ectopic hnRNP K markedly suppressed the inhibition of invasion by knock-down of endogenous hnRNP K. The expression level of matrix metalloproteinase protein-2 was decreased by endogenous hnRNP K knock-down, and restored by ectopic hnRNP K. Therefore, hnRNP K may be a key molecule involved in cell motility in RCC cells, and molecular mechanism associated with the subcellular localization of hnRNP K may be a novel target in the treatment of metastatic RCC.     

Clinicopathologica Epidemiological Characteristics and Change Tendencies of Renal Cell Carcinoma in Shanxi Province of China from 2005 to 2014

Objectives

RCC is the most common solid renal malignancy in adults worldwide. To provide the insight of clinicopathologica epidemiological characteristics and change tendencies of renal cell carcinoma (RCC), 2154 cases were collected from Shanxi Province of China, including diagnose time, age, gender, tumor size, Fuhrman grade, tumor stage, tumor location, local advance or distant metastasis and first symptom from 2005 to 2014. This retrospectively investigation, as its general objective, was to analyze the clinicopathologica epidemiological characteristics and the change tendencies of RCC.

Methods

Between 2005 and 2014, 2154 patients who were diagnosed with RCC in three large tertiary hospitals at Shanxi Province were included. The patients’ demographic features, pathological diagnoses and metastatic statuses were analyzed. Statistics methods include the chi-squared test, analysis of variance, Spearman’s correlation analysis, Logistic regression and ARIMA modeling.

Results

Of the 2154 included patients, the constituent ratio of female /male was 63.1% and 36.9%, with the median age of 57 years old. Fuhrman grade distributions differed significantly between males and females (p = 0.024). Also, a significant difference in tumor size was found by different clinical stages (p < 0.001), with a linear correlation (p < 0.001). Moreover, Spearman’s analysis indicated tumor grade has a negative correlation with female (p = 0.009) and a positive correlation with tumor size (p = 0.000). It was found that the tumor diameter is bigger in the left side (p = 0.022). Furthermore, the metastasis rate was higher in the bigger tumor (p < 0.001) and the left-sided tumors (p = 0.027). Logistic regression also showed that tumor size is a risk factor for metastasis (OR = 1.724). The risk of local advance or distant metastasis in the left kidney was 1.6-fold greater than that of the right kidney. From 2005 to 2014 the number of RCC cases gradually increased (mainly for pathological grade II and III, but grade I and IV), while the average tumor size decreased, showing the severity increase mildly. Base on the results of a time series analysis-prediction the average RCC size would continue to decrease from the first quarter of 2015 to the fourth quarter of 2016.

Conclusions

The cases of RCC increased from 2005 to 2014 with clear cell type as the main pathological type in this population. The characteristics in the constituent ratios of the RCC vary depending on gender, pathological grade, tumor size, and location, which may be the important factors impacting treatment and prognosis.     

The expression of ketohexokinase is diminished in human clear cell type of renal cell carcinoma

For identification and targeting of tumor-associated marker proteins, the proteome of clear cell type of renal cell carcinoma (RCC) and normal kidney tissues was analyzed by 2-DE. Ketohexokinase (also called fructokinase), which catalyzes the phosphorylation of fructose to fructose 1-phosphate, was identified by MALDI-TOF MS and found to be expressed at low rates in the renal tumor tissues. We found a decreased amount of ketohexokinase mRNA in RCC compared to that observed in the normal kidney tissues by Northern blot. The activity of ketohexokinase in 20 clear cell RCC specimens and the 20 corresponding normal kidneys was investigated, and its activity was shown to be approximately 1.4-fold lower in the RCC specimens than in the normal kidney. Ketohexokinase activity in tumor stage pT3 RCC was 1.5-fold lower than in pT1 RCC. The level of ketohexokinase activity in histological grade 3 RCC was 1.8-fold lower than that in grade 1 cancer. In addition, using in situ hybridization, it was revealed that ketohexokinase in the normal kidney tissue was confined to the proximal tubular epithelial cells, while the expression of ketohexokinase in RCC tissues was extremely low. Our research results show that the expression of human ketohexokinase was diminished in clear cell RCC.     

Multilocular cystic renal cell carcinoma with focus on clinical and pathobiological aspects

Multilocular cystic renal cell carcinoma (MCRCC) accounts for approximately 1 to 2% of all renal tumors. This tumor is currently classified as a subtype of clear cell RCC. Clinically, the majority of these tumors are incidentally found. Macroscopically, the tumor is well demarcated and consists of various-sized cysts. The fibrous septa are generally thin and there is no discernible expansile nodule. Microscopically, the cyst walls are lined with tumor cells with clear to occasionally slightly eosinophilic cytoplasm. The Fuhrman nuclear grade is generally low and usually corresponds to grade 1. The deletion of chromosome 3p was identified in most tumors using FISH analysis and VHL gene mutation was identified in 25% of MCRCC. As MCRCC generally exhibits a low stage of TNM classification, the great majority of these tumors have a favorable clinical course. To date, there are no reports of metastasis, vascular invasion or sarcomatoid change in MCRCC. Accordingly, nephron sparing surgery is first recommended as a therapeutic strategy.     

Expression of intermediate-sized filaments in developing and adult human kidney and in renal cell carcinoma.

We studied the distribution of intermediate-sized filaments in developing and adult kidneys and renal cell carcinoma (RCC) by indirect immunohistochemistry, using a pan-cytokeratin mouse monoclonal antibody (MAb), chain-specific anti-cytokeratin MAb, and anti-vimentin and anti-desmin MAb, to resolve controversy concerning intermediate-sized filament expression in the kidney. With the pan-cytokeratin MAb, cytokeratin expression was detectable in all stages of nephron development, starting with expression in the renal vesicles, the progenitors of the glomeruli, proximal tubules, Henle's loop, and part of the distal tubules. Using chain-specific anti-cytokeratin MAb, cytokeratin 8 and 18 expression was demonstrated in all developmental structures of the nephron, whereas cytokeratin 19 expression was more complex. None of the nephrogenic blastema cells from which the renal vesicles arise expressed cytokeratins. Transient expression of vimentin and cytokeratin 19 was observed in differentiating collecting ducts and proximal tubule cells at the S-shaped stage of nephron development, respectively. In RCC, cytokeratin expression closely resembled that of the mature proximal tubule, i.e., RCC cells expressed cytokeratins 8 and 18. However, in a subset of RCC additional cytokeratin 19 expression was noted. In addition, all except one RCC showed co-expression of cytokeratins and vimentin.     

Redox state and carbonic anhydrase isozyme IX expression in human renal cell carcinoma: biochemical and morphological investigations

Clear renal cell carcinomas (RCC) frequently express carbonic anydrase IX (CA IX) because of non-functional mutation of von Hippel Lindau (VHL) tumor suppressor gene. CA IX is a tumor-associated transmembrane antigen, which catalyzes the extracellular, reversible hydration of carbon dioxide to bicarbonate and proton and thereby contributes to acidification of extracellular milieu. Extracellular acidic pH facilitates tumor growth and progression. CA IX expression is upregulated by Hypoxia Inducible Factor-1 (HIF-1), which is negatively controlled by oxygen via wild type VHL protein and is also regulated by the cell redox state. We investigated the immunohistochemical pattern of distribution of CA IX in a small series (14 cases) of RCCs. CA IX expression was matched with the redox state of RCC, stratifying our series in relation to clinical and histopathological parameters, such as Fuhrman grade, staging, proliferation markers expression, and particularly, the presence of necrosis. Our results show for the first time the existence of a perivascular pattern of CA IX distribution in RCC. We also found a significant relationship between CA IX expression and the presence of necrosis. Tumors with higher CA IX expression exhibited higher degree of necrosis (p < 0.05). Notably, an almost significant relationship between the redox state and CA IX expression was detected in RCC patients with 5 years disease-free survival, most of them showing organ-confined disease. Tumors with lower redox state showed an algebraically higher degree of CA IX expression. On the contrary, tumors with higher redox state exhibited an algebraically lower CA IX expression (p = 0.057). The observed relationship of CA IX expression and necrosis suggests a role for CA IX in RCC. Further investigations are necessary to further establish the role of the redox state in regulation of CA IX expression in RCC.     

赖氨酰氧化酶样蛋白2在肾细胞癌中的表达及其临床意义

为探究赖氨酰氧化酶样蛋白2 (lysyl oxidase like 2, LOXL2)与肾细胞癌(renal cell carcinoma, RCC)的关系,本研究采用免疫组织化学方法检测58例RCC组织及13例癌旁组织中LOXL2的表达水平,并利用统计学方法进一步分析LOXL2与临床病理参数和预后之间的关系。研究显示,LOXL2在癌组织和癌旁组织的阳性表达率分别为68.96%和23.08%,差异具有统计学意义(p<0.05)。LOXL2阳性表达与患者的临床分期和肾包膜浸润相关(p<0.05),但是与患者的性别、年龄、吸烟、病理类型、肿瘤大小和肿瘤分级均无相关性(p>0.05)。采用Kaplan-Meier法和Log-Rank检验分析LOXL2与术后生存时间的关系,实验显示LOXL2阳性组和阴性组患者的5年生存率分别为61.58%和89.46%,差异具有统计学意义(p<0.05)。我们的研究表明LOXL2在肾癌中过表达,其可能在肾癌的侵袭和转移过程中发挥作用,可作为预后的分子标记物。     

Redox State and Carbonic Anhydrase Isozyme IX Expression in Human Renal Cell Carcinoma: Biochemical and Morphological Investigations

Clear renal cell carcinomas (RCC) frequently express carbonic anydrase IX (CA IX) because of non-functional mutation of von Hippel Lindau (VHL) tumor suppressor gene. CA IX is a tumor-associated transmembrane antigen, which catalyzes the extracellular, reversible hydration of carbon dioxide to bicarbonate and proton and thereby contributes to acidification of extracellular milieu. Extracellular acidic pH facilitates tumor growth and progression. CA IX expression is upregulated by Hypoxia Inducible Factor-1 (HIF-1), which is negatively controlled by oxygen via wild type VHL protein and is also regulated by the cell redox state. We investigated the immunohistochemical pattern of distribution of CA IX in a small series (14 cases) of RCCs. CA IX expression was matched with the redox state of RCC, stratifying our series in relation to clinical and histopathological parameters, such as Fuhrman grade, staging, proliferation markers expression, and particularly, the presence of necrosis. Our results show for the first time the existence of a perivascular pattern of CA IX distribution in RCC. We also found a significant relationship between CA IX expression and the presence of necrosis. Tumors with higher CA IX expression exhibited higher degree of necrosis [Formula: See Text] Notably, an almost significant relationship between the redox state and CA IX expression was detected in RCC patients with 5 years disease-free survival, most of them showing organ-confined disease. Tumors with lower redox state showed an algebraically higher degree of CA IX expression. On the contrary, tumors with higher redox state exhibited an algebraically lower CA IX expression [Formula: See Text] The observed relationship of CA IX expression and necrosis suggests a role for CA IX in RCC. Further investigations are necessary to further establish the role of the redox state in regulation of CA IX expression in RCC.     

Downregulation of junctional adhesion molecule-A is involved in the progression of clear cell renal cell carcinoma

Junctional adhesion molecule-A (JAM-A) is one component of tight junctions which are involved in important processes like paracellular permeability, cell polarity, adhesion, migration, and angiogenesis. Here we describe JAM-A expression in distal convoluted tubule, connecting tubule, and in cells of the collecting duct of the healthy human kidney. In addition, JAM-A was weakly expressed in cells of the proximal tubule. Using immunofluorescence, FACS and Western blot analysis we investigated JAM-A expression in tubular cells in vitro. Interestingly, treatment of HK-2 cells with IFN-γ and TNF-α resulted in a metalloproteinase mediated downregulation of JAM-A. Importantly, in a tissue micro-array JAM-A protein expression was significantly downregulated in patients with clear cell renal cell carcinoma. Furthermore, knockdown of JAM-A with JAM-A specific siRNA induced the migration of RCC4 cells. In summary, downregulation of JAM-A is an early event in the development of renal cancer and increases the migration of renal cancer cells.     

Prognostic significance of metallothionein expression in renal cell carcinoma

BACKGROUND: Metallothionein (MT) protein expression deficiency has been implicated in carcinogenesis while MT over expression in tumors is indicative of tumor resistance to anti-cancer treatment. The purpose of the study was to examine the expression of MT expression in human renal cell carcinoma (RCC) and to correlate MT positivity, the pattern and extent of MT expression with tumor histologic cell type and nuclear grade, pathologic stage and patients' survival. PATIENTS AND METHODS: The immunohistochemical expression of MT was determined in 43 formalin-fixed and paraffin-embedded RCC specimens, using a mouse monoclonal antibody that reacts with both human MT-I and MT-II. Correlation was sought between immunohistochemical (MT positivity, intensity and extension of staining) and clinico-pathological data (histological cell type, tumor nuclear grade, pathologic stage and patients' survival). RESULTS: Positive MT staining was present in 21 cases (49%), being mild/moderate and intense in 8 and 13 cases, respectively. The pattern was cytoplasmic in 7 cases and was both cytoplasmic and nuclear in 14 cases. MT expression in a percentage of up to 25% of tumor cells (negative MT staining included) was observed in 31 cases, in a percentage 25-50% of tumor cells in 7 cases, and in a percentage of 50-75% of tumor cells in 5 cases. There was no significant correlation of MT intensity of staining to histological type, stage and patients' survival, while it was inversely correlated to higher tumor nuclear grade. MT extent of staining did not correlate with histological type, nuclear grade, and pathologic stage while a statistically significant association was found with patients' survival. CONCLUSIONS: The inverse correlation between MT staining intensity and tumor nuclear grade in RCC suggests a role of MT in tumor differentiation process. Since extent of MT expression is inversely correlated with survival it may be possibly used as a clinical prognostic parameter.     

Serum exosomal miR-210 as a potential biomarker for clear cell renal cell carcinoma

Exosomal microRNAs (miRNAs) are suggested to reflect molecular changes occurring in their cells of origin and are potential indicators in the early detection of cancers. This study aimed to determine whether certain exosomal miRNAs from tumor tissue can be used as noninvasive biomarkers for clear cell renal cell carcinoma (ccRCC). Based on ccRCC miRNA expression profiles and the literature, we selected six miRNAs (miR-210, miR-224, miR-452, miR-155, miR-21, and miR-34a) and analyzed their expression in tissues, sera, and serum exosomes through quantitative real-time polymerase chain reaction in hypoxia-induced (with CoCl₂) renal cell lines. miR-210, miR-224, miR-452, miR-155, and miR-21 were upregulated in tumor tissues compared with normal tissues. Serum miR-210 and miR-155 levels were higher in patients with ccRCC than in healthy controls (HCs). Furthermore, only exosomal miR-210 was significantly upregulated in patients with ccRCC than in HCs. Moreover, receiver operating characteristic (ROC) curve analysis revealed an area under the ROC curve of 0.8779 (95% confidence interval, 0.7987-0.9571) and a sensitivity and specificity of 82.5% and 80.0%, respectively. Moreover, exosomal miR-210 was upregulated at an advanced stage, and Fuhrman grade and metastasis decreased significantly one month after surgery. Acute hypoxia exposure activates miR-210 and release of exosomes with upregulated miR-210 in both normal and tumor RCC cell lines and interferes with vacuole membrane protein 1 mRNA expression, especially in the metastatic ccRCC cell line. In conclusion, Serum exosomal miR-210 originating from tumor tissue has potential as a novel noninvasive biomarker for the detection and prognosis of ccRCC.     

A Comparison of Radiologic Tumor Volume and Pathologic Tumor Volume in Renal Cell Carcinoma (RCC)

Objective

To investigate the difference between preoperative radiologic tumor volume (RTV) and postoperative pathologic tumor volume (PTV) in patients who received nephrectomy for renal cell carcinoma (RCC).

Materials and Methods

We reviewed 482 patients who underwent preoperative computed tomography (CT) within 4 weeks before radical or partial nephrectomy for renal cell carcinoma. RTV measured by a three dimensional rendering program was compared with PTV (π/6ⅹheightⅹlengthⅹwidth) measured in surgical specimen according to pathologic tumor size and histologic subtype. Correlation of the inter-quartile range (IQR) of the RTV and Fuhrman nuclear grade was also investigated.

Results

There was a significant positive linear correlation between RTV and PTV (p<0.001, r = 0.911), and the mean RTV and mean PTV were not significantly different (79.0 vs 76.9cm³, p = 0.393). For pathologic tumor size (PTS) <4cm, the mean RTV was larger than the mean PTV (10.9 vs 7.1cm³, p<0.001). For a PTS of 4-7cm, the mean RTV was larger than the mean PTV (56.0 vs 44.7cm³, p<0.001). However, for a PTS ≥7cm, there was no statistical difference between RTV and PTV (p>0.05). Among patients with clear cell RCC, the mean RTV was significantly larger than the mean PTV (p = 0.042), not for non-clear cell group (p = 0.055). As the quartile of the RTV increased, the Fuhrman grade also increased (p<0.001).

Conclusions

RTV was correlated with PTV and pathologic grade. RTV was larger than the PTV for a tumor size 7 cm or less or in clear cell RCC. RTV may be useful to measure tumor burden preoperatively.     

Discordant lymphoma consisting of mediastinal large B-cell lymphoma and nodular sclerosis Hodgkin lymphoma in the right supraclavicular lymph nodes: a case report

PD-L1 is a glycoprotein from the family of T-cell co-stimulatory molecules that are constitutively expressed by macrophages. Aberrant expression of PD-L1 is observed in human cancers associated with inhibition of the tumor-directed T-cell immune response. There are few reports in the literature evaluating PD-L1 expression in association to prognosis specifically in renal cell cancer clear cell type (RCC-CC). Immunohistochemistry using a PD-L1 polyclonal antibody was performed on a tissue microarray (TMA) that contained 115 surgical specimens of RCC-CC. Cases were classified based on the absence or presence of staining intensity in the cytoplasm and membranes of the tumor cells. Statistical analysis was used to determine the association of PD-L1 expression with classic prognostic factors and tumor recurrence. PD-L1 expression was positive in 56.5 % of tumors. The univariate analysis showed a correlation between PD-L1 expression and nuclear Fuhrman grade (p = 0.021) and microvascular tumor embolization (p = 0.039). One hundred and four patients were monitored for a mean time of 115.7 months. Seventeen patients (16.3 %) suffered tumor recurrence. Negative outcomes were associated with higher nuclear grade tumors, PD-L1 expression, and the presence of microvascular invasion. Our findings confirm that PD-L1 expression is an important prognostic factor in RCC-CC.     

P63 immunoreactivity distinguishes upper urinary tract transitional-cell carcinoma and renal-cell carcinoma even in poorly differentiated tumors.

P63 is essential for the differentiation of normal urothelium and is also expressed in transitional cell carcinoma (TCC) of the bladder. We investigated p63 immunoreactivity in upper urinary tract TCC (n=53) and in renal-cell carcinoma (RCC; n=188) using a tissue microarray technique. P63 expression was detected in 51/53 (96.2%) TCCs, showing decreased expression in high-stage (pT1 and pT2 100%; pT3 90.9%) and poorly differentiated (G1 and G2 100%; G3 92%) tumors. All RCCs were negative for p63. P63 proved to be a helpful tool, even in poorly differentiated and undifferentiated renal malignancies, to distinguish TCC from RCC.     

The murine receptor for urokinase-type plasminogen activator is primarily expressed in tissues actively undergoing remodeling.

uPAR is a cellular receptor for urokinase plasminogen activator, an enzyme involved in extracellular matrix degradation during processes involving tissue remodeling. We have expressed a recombinant soluble form of murine uPAR and raised rabbit polyclonal antibodies to study the expression of uPAR by immunohistochemistry. The immunohistochemical localization of uPAR was determined in normal mouse organs and in tumors formed by the highly metastatic Lewis lung carcinoma. uPAR immunoreactivity was found in the lungs, kidneys, and spleen, and in endothelial cells in the uterus, urinary bladder, thymus, heart, liver, and testis. No uPAR immunoreactivity was detected in muscle. In general, strong uPAR immunoreactivity was observed in organs undergoing extensive tissue remodeling, as exemplified by trophoblast cells in placenta, and in migrating, but not resting, keratinocytes at the edge of incisional wounds. Staining was not detected in any tissue sections derived from uPAR-deficient mice, thus confirming the specificity of the immunohistochemical staining of uPAR in normal mouse tissues. In Lewis lung carcinoma, uPAR immunoreactivity was found in the tumor cells of the primary tumor and in lung metastases. (J Histochem Cytochem 49:237-246, 2001)