Journal of Histochemistry & Cytochemistry

Degradation of the extracellular matrix and basement membrane is a critical step in tumor progression. Matrix metalloproteinase 2 (MMP-2) and tissue inhibitor of metalloproteinase 2 (TIMP 2) act in a coordinated manner to form an integrated system involved in ovarian cancer (OC) progression. In this study, the authors describe the expression of TIMP-2 detected by immunohistochemistry in 6 OC cell lines and in 43 malignant epithelial ovarian tumors (in tumor and stromal compartments) in sections originating from primary laparotomies. No significant correlations between overall and progression-free survival and TIMP-2 expression in tumor compartment were observed. The analysis demonstrated a significant association between enhanced stromal expression of TIMP-2 and better clinical response to cisplatin- and paclitaxel-based chemotherapy. Increased expression of TIMP-2 in the stromal compartment and simultaneous overexpression in both stromal and tumor compartments strongly correlated with increased survival. No significant correlations were found in vitro between resistance to cisplatin, paclitaxel, or topotecan and the expression of TIMP-2 in the OC cell lines, suggesting stromal influences on tumor chemoresistance in the physiological environment. This study supports the concept of TIMP-2 expression in the stromal compartment of OC as a promising marker of prognosis and response to cisplatin- and paclitaxel-based chemotherapy in OC patients.

1,25-DihydroxyvitaminD₃ (1,25(OH)₂D₃), the active form of vitamin D, mediates antitumor effects in various cancers. The expression of key players in vitamin D signaling in thyroid tumors was investigated. Vitamin D receptor (VDR) and CYP27B1 and CYP24A1 (respectively activating and catabolizing vitamin D) expression was studied (RT-PCR, immunohistochemistry) in normal thyroid, follicular adenoma (FA), differentiated thyroid cancer (DTC) consisting of the papillary (PTC) and follicular (FTC) subtype, and anaplastic thyroid cancer (ATC). VDR, CYP27B1, and CYP24A1 expression was increased in FA and DTC compared with normal thyroid. However, in PTC with lymph node metastasis, VDR and CYP24A1 were decreased compared with non-metastasized PTC. In ATC, VDR expression was often lost, whereas CYP27B1/CYP24A1 expression was comparable to DTC. Moreover, ATC with high Ki67 expression (>30%) or distant metastases at diagnosis was characterized by more negative VDR/CYP24A1/CYP27B1 staining. In conclusion, increased expression of key players involved in local 1,25(OH)₂D₃ signaling was demonstrated in benign and differentiated malignant thyroid tumors, but a decrease was observed for local nodal and especially distant metastasis, suggesting a local antitumor response of 1,25(OH)₂D₃ in early cancer stages. These findings advocate further studies with 1,25(OH)₂D₃ and analogs in persistent and recurrent iodine-refractory DTC.

The human cervical cancer oncogene 1 (HCCR-1), a novel human oncoprotein, has been shown to be upregulated in various human tumors and plays a critical role in tumorigenesis and tumor progression. Here, the authors investigated HCCR-1 level in esophageal squamous cell carcinoma (ESCC) tissues and assessed the correlation between HCCR-1 level and prognosis of the patients with ESCC. HCCR-1 levels were investigated by immunohistochemistry, in situ hybridization, real-time quantitative RT-PCR and Western blotting methods; Kaplan-Meier curve was used to evaluate the prognostic value of HCCR-1 level in patients with ESCC using log-rank test. HCCR-1 displayed high levels in ESCC tissues compared to squamous dysplasia tissues and normal esophageal epithelial tissues. No significant correlation was observed between the levels of HCCR-1 mRNA and protein and gender and age (all p>0.05) but obviously related to histological grade, clinical stage, and lymph node metastasis (all p<0.001). Moreover, the survival rate of the patients with low HCCR-1 levels was higher than that of the patients with high HCCR-1 levels (both p<0.05). These data demonstrate that HCCR-1 may be used as a novel predictor for the prognosis of the patients with ESCC.

Cisplatin is a widely used antineoplastic agent. However, its major limitation is dose-dependent nephrotoxicity whose precise mechanism is poorly understood. Recent studies have suggested that mitochondrial dysfunction in tubular epithelium contributes to cisplatin-induced nephrotoxicity. Here the authors extend those findings by describing the role of an important electron transport chain enzyme, cytochrome c oxidase (COX). Immunohistochemistry for COX 1 protein demonstrated that, in response to cisplatin, expression was mostly maintained in focally damaged tubular epithelium. In contrast, COX enzyme activity in proximal tubules (by light microscopy) was decreased. Ultrastructural analysis of the cortex and outer stripe of the outer medulla showed decreased mitochondrial mass, disruption of cristae, and extensive mitochondrial swelling in proximal tubular epithelium. Functional electron microscopy showed that COX enzyme activity was decreased in the remaining mitochondria in the proximal tubules but maintained in distal tubules. In summary, cisplatin-induced nephrotoxicity is associated with structural and functional damage to the mitochondria. More broadly, using functional electron microscopy to measure mitochondrial enzyme activity may generate mechanistic insights across a spectrum of renal disorders.

A new multicolor fluorescence in situ hybridization (mFISH) probe set is presented, and its possible applications are highlighted in 25 clinical cases. The so-called heterochromatin-M-FISH (HCM-FISH) probe set enables a one-step characterization of the large heterochromatic regions within the human genome. HCM-FISH closes a gap in the now available mFISH probe sets, as those do not normally cover the acrocentric short arms; the large pericentric regions of chromosomes 1, 9, and 16; as well as the band Yq12. Still, these regions can be involved in different kinds of chromosomal rearrangements such as translocations, insertions, inversions, amplifications, and marker chromosome formations. Here, examples are given for all these kinds of chromosomal aberrations, detected as constitutional rearrangements in clinical cases. Application perspectives of the probe set in tumors as well as in evolutionary cytogenetic studies are given.

Osteoclasts are bone-resorbing multinucleated cells that undergo drastic changes in their polarization due to heavy vesicular trafficking during the resorption cycle. These events require the precise orchestration of membrane traffic in order to maintain the unique characteristics of the different membrane domains in osteoclasts. Rab proteins are small GTPases involved in regulation of most, if not all, steps of vesicle trafficking. The investigators studied RAB genes in human osteoclasts and found that at least 26 RABs were expressed in osteoclasts. Out of these, RAB13 gene expression was highly upregulated during differentiation of human peripheral blood monocytic cells into osteoclasts. To study its possible function in osteoclasts, the investigators performed immunolocalization studies for Rab13 and various known markers of osteoclast vesicular trafficking. Rab13 localized to small vesicular structures at the superior parts of the osteoclast between the trans-Golgi network and basolateral membrane domain. Rab13 localization suggests that it is not involved in endocytosis or transcytosis of bone degradation products. In addition, Rab13 did not associate with early endosomes or recycling endosomes labeled with EEA1 or TRITC-conjugated transferrin, respectively. Its involvement in glucose transporter traffic was excluded as well. It is suggested that Rab13 is associated with a putative secretory function in osteoclasts.

The present study was designed to evaluate the extent and topography of osteopontin (OPN) protein expression in the rat hippocampus 4 to 12 weeks following transient forebrain ischemia, and to compare OPN expression patterns with those of calcium deposits and astroglial and microglial reactions. Two patterns of OPN staining were recognized by light microscopy: 1) a diffuse pattern of tiny granular deposits throughout the CA1 region at 4 weeks after ischemia and 2) non-diffuse ovoid to round deposits, which formed conglomerates in the CA1 pyramidal cell layer over the chronic interval of 8 to 12 weeks. Immunogold-silver electron microscopy and electron probe microanalysis demonstrated that OPN deposits were indeed diverse types of calcium deposits, which were clearly delineated by profuse silver grains indicative of OPN expression. Intracellular OPN deposits were frequently observed within reactive astrocytes and neurons 4 weeks after ischemia but rarely at later times. By contrast, extracellular OPN deposits progressively increased in size and appeared to be gradually phagocytized by microglia or brain macrophages and some astrocytes over 8 to 12 weeks. These data indicate an interaction between OPN and calcium in the hippocampus in the chronic period after ischemia, suggesting that OPN binding to calcium deposits may be involved in scavenging mechanisms.