Kyu-Yun Jang

Disruption of a regulatory loop between DUSP1 and p53 contributes to hepatocellular carcinoma development and progression.

BACKGROUND & AIMS Altered expression of dual specificity phosphatase 1 (DUSP1) is common in tumors including hepatocellular carcinoma (HCC), and is predictive of tumor progression and poor prognosis. However, the tumor suppressive role of DUSP1 has yet to be clearly elucidated. METHODS The molecular mechanisms of tumor suppression that were investigated were induction of apoptosis, cell cycle inhibition, and regulation of p53. Additionally, the antitumor effect of DUSP1 was assessed using a mouse model. Associated signaling pathways in HCC cells and tissues were examined. RESULTS Downregulation of DUSP1 expression was significantly correlated with poor differentiation (p<0.001) and advanced HCC stage (p=0.023). DUSP1 expression resulted in HCC suppression and longer survival (p=0.0002) in a xenoplant mice model. DUSP1 inhibited p38 MAPK phosphorylation and subsequently suppressed HSP27 activation, resulting in enhanced p53 phosphorylation at sites S15, S20, and S46 in HCC cells. Enhanced p53 activation induced the expression of target genes p21 and p27, which are linked to cell cycle arrest and apoptosis. Thus, DUSP1 was potentially linked to p53 activation via the p38 MAPK/HSP27 pathway. Wild-type but not mutant p53 transcriptionally upregulated DUSP1 via its DNA-binding domain. DUSP1 and p53 might collaborate to suppress tumors in hepatocarcinogenesis via a positive regulatory loop. CONCLUSIONS Our results revealed that disruption of a positive regulatory loop between DUSP1 and p53 promoted HCC development and progression, providing a rationale for a therapeutic agent that restores DUSP1 in HCC.

In vivo inhibition of bone morphogenetic protein-2 on breast cancer cell growth.

Study Design. In vitro and in vivo study. Objective. To evaluate the role of recombinant human bone morphogenetic protein-2 (rhBMP2) on breast cancer cell (MDA-MB-231 cells) growth. Summary of Background Data. Bone morphogenetic proteins (BMPs) are expressed in a variety of human carcinoma cell lines and are known to promote tumor invasion and metastasis. However, their roles in tumor progression have not been fully clarified. In addition, there is no in vivo study regarding the inhibitory effect of BMP2 on breast cancer cell proliferation. Method. Cell proliferation was determined by BrdU incorporation assay and flow cytometry. BMP2 signal transduction pathways were estimated on Western blot. Fifteen animals were divided into 2 groups; 1 (control = 5) was breast cancer cells alone, while the other (experiment = 5) was rhBMP2 + breast cancer cells. Cancer cells were injected into 2 sites (subcutaneous and femur) of nude mice with or without BMP2. Tumor size was determined by direct measurements for subcutaneous tumor formation and by femur radiographs. Histological and immunohistochemical analyses were performed. Results. RhBMP2 inhibited the proliferation of MDA-MB-231 cells in vitro. Inhibition was associated with changes in both the Smad and Wnt signaling pathways and was ultimately mediated through effects on various cell cycle proteins. Furthermore, rhBMP2 inhibited the growth of MDA-MB-231 cells injected both subcutaneously and intrafemorally. Conclusion. In this model using human breast adenocarcinoma cell line, rhBMP2 has no stimulatory effect of tumor growth. Therefore, we can provide the basic science data to support the utilization in the management of patients with spine tumor in the future.

Comparison of the osteogenic potential of bone dust and iliac bone chip

BACKGROUND CONTEXT There is no comparative study of the in vitro and in vivo osteogenic potential of iliac bone chips (autogenous iliac cancellous bone chips) compared with bone dusts generated during the decortication process with a high-speed burr in spine fracture or fusion surgery. PURPOSE To compare the osteogenic potential of three sizes of bone dusts with iliac bone chips and to determine whether bone dusts can be used as a bone graft substitute. STUDY DESIGN In vitro and in vivo study. METHODS Bone chips were harvested from the posterior superior iliac spine and bone dusts from the vertebrae of 15 patients who underwent spinal fracture surgery. Bone dust was divided into three groups: small (3 mm), middle (4 mm), and large (5 mm) according to the size of the burr tip. A comparison was made using a cell proliferation assay, alkaline phosphatase (ALP) activity, the degree of mineralization in an in vitro model, and radiographic and histologic studies (the change of absorbable area and tissue density) after implantation of the various materials into back muscles of nude mice. RESULTS Although all three bone dust groups were less active with regard to cell proliferation, ALP activity, and the degree of mineralization, than were bone chips, they still exhibited osteogenic potential. Furthermore, there was no significant difference among the three bone dust groups. The three bone dust groups did show greater absorbable area and change of the tissue density than did the iliac bone chip group. Again, there was no significant difference among the three bone dust groups in this regard. Histologically, specimens from the bone dust groups had a higher osteoclast cell number than specimens from the iliac bone chip group. CONCLUSIONS The osteogenic potential of bone dusts is lower than that of iliac bone chips, and the absorption speed of bone dusts in vivo is faster than that of iliac bone chips. The increased resorption speed appeared to result from an increase in osteoclast cell number. Therefore, caution needs to be used when surgeons employ bone dust as a bone graft substitute.

Effects of Diclofenac Sodium on BMP-induced Inflammation in a Rodent Model.

Study Design. Prospective in vivo rodent model of bone morphogenetic protein (BMP)-induced inflammation. Objective. To evaluate the effects of the coadministration of the nonsteroidal anti-inflammatory drug, diclofenac, on BMP-induced inflammation using our rodent model. Summary of Background Data. The use of BMP-2 is associated with inflammation in the neck and back. We have previously reported on a rodent model of BMP-2-induced inflammation. Methods. Seven treatment groups were: Surgery alone; absorbable collagen sponges (ACS) alone; 20 &mgr;g rhBMP-2 on ACS with no diclofenac; 20 &mgr;g rhBMP-2 on ACS+50 mg diclofenac injections; 20 &mgr;g rhBMP-2 on ACS+75 mg diclofenac; 20 &mgr;g rhBMP-2 on ACS+100 mg diclofenac; and 20 &mgr;g rhBMP-2 on ACS+125 mg diclofenac. Using magnetic resonance imaging, inflammation (soft tissue edema volume) was assessed at 3 hours and at 2, 7, and 14 days after implantation. Western blot analysis, histology, and immunohistochemical staining were performed to compare the inflammatory response between groups. The mass size and tissue density of bone formation were compared between groups using plain radiography. Results. Soft-tissue edema volumes in all diclofenac-treated groups were significantly lower than those observed in the rhBMP-2 alone. There was no significant difference in soft tissue edema volumes between 4 diclofenac-treated groups. The expression of NF-&kgr;B signaling pathway related proteins (p65 and p-p65) were increased in the rhBMP-2+ACS group and decreased in diclofenac treatment groups. Histological findings and immunohistochemical staining were consistent with the Western blot results. There was no significant difference between the rhBMP-2+ACS group and diclofenac treatment groups in terms of the mass size and tissue density of bone formation. Conclusion. Coadministration of diclofenac sodium can reduce the inflammatory response to BMP-2 without impairing heterotopic bone formation in our rodent model of BMP-2-induced inflammation. Level of Evidence: N/A

Increase of NAD glycohydrolase activity in uterine cervix cancers is caused by infiltration of lymphocytes

CD38 is a type II transmembrane glycoprotein which is expressed by hematopoietic and nonhematopoietic cells in human. It has two functions of ADP-ribosyl cyclase and cyclic ADP-ribose hydrolase activities and the sum of these two enzyme activities is identical with NAD glycohydrolase (NADase) activity. The levels of NADase activity in human cervical carcinoma and normal cancer tissue were measured. With a total of 12 patients with cervical cancer and 11 women with normal cervix, cancer tissues were found to have significantly higher NADase and ADP-ribosyl cyclase activities than the control group. Moreover, immunoblot analysis showed an increase of immunoreactivity against CD38 in cervical cancer tissues compared with normal tissues. Immunohistochemical data indicated that the increase of CD38 expression was due to increased infiltration of lymphocytes.

Alterations in the p53-SOCS2 axis contribute to tumor growth in colon cancer

Altered expression of suppressor of cytokine signaling (SOCS) is found in various tumors. However, regulation of SOCS2 by upstream molecules has yet to be clearly elucidated, particularly in tumor cells. SCOCS2 expression was examined in tumor cells transfected with an inducible p53 expression system. The impact of SOCS2 on cell proliferation was measured with in vitro assays. Inhibition of tumorigenicity by SOCS2 knockdown was assessed via a mouse model. Expression profiles were compared and genes differentially expressed were identified using four types of p53-null cells (Saos, HLK3, PC3, and H1299) and the same cells stably expressing p53. Twelve kinds of target genes were simultaneously upregulated or downregulated by p53 in three or more sets of p53-null cells. SOCS2 expression was reciprocally inhibited by inducible p53 expression in p53-null cells, even colon cancer cells. SOCS2 promoter activity was inhibited by wild type but not mutant p53. SOCS2 knockdown inhibited tumor growth in vitro and in an animal xenograph model. SOCS2 overexpression was detected in a murine model of azoxymethane/dextran sulfate sodium-induced colitis-associated colon cancer compared to mock-treated controls. SOCS2 expression was heterogeneously upregulated in some human colon cancers. Thus, SOCS2 was upregulated by p53 dysfunction and seemed to be associated with the tumorigenic potential of colon cancer.Colon cancer: A delicate balance to regulate growthInsights into a signaling protein’s role in cell growth could inform new therapeutic strategies for treating colon cancer. SOCS-2 acts as an ‘off switch’ for cell signaling pathways. It has been identified as possibly protective against many cancers, although some cancers are associated with elevated SOCS-2 levels. Researchers led by Daeghon Kim at Chonbuk National University Hospital in South Korea have now shown that the effects of SOCS-2 are apparently dependent on how much of it is present. Moderate levels of SOCS-2 can suppress growth in colon cancer cells, but Kim’s team showed that excessive SOCS-2 has the opposite effect, promoting proliferation. The researchers also identified a gene commonly mutated in cancer cells that can drive overproduction of SOCS-2. Drugs that inhibit SOCS-2 or block its production may therefore offer useful treatments for colorectal cancer.

Bizarre leiomyoma of the soft tissue

Sir, Bizarre leiomyoma of soft tissue has been previously described rarely. There have been only two cases of bizarre leiomyoma reported in the nasal cavity but none at all in the nasolabial fold, although a few cases of leiomyoma have been reported in the nasal cavity and paranasal sinuses. A 34-year-old man had been suffering from a mass in the nasolabial fold for 1 year. The patient had an unremarkable clinical history, except for untreated hypertension and flank pain. On examination, a soft, indolent, and movable mass was observed on the left nasolabial fold. Rhinoscopic examination displayed mild septal deviation on the right side, and elevation of the nasal floor. Under the clinical impression of a nasolabial cyst, the mass was completely excised by sublabial approach. Grossly, the specimen consisted of a 30622620 mm solid mass. The mass exhibited soft yellow colouration with haemorrhaging on the cut surface. Microscopically, the lesion was well circumscribed, and revealed overall hypercellularity, excepting the haemorrhagic and focal loose stromal areas (Fig. 1). There were small-sized, thinwalled vessels, but no thick-walled vessels in hypercellular areas. The hypercellular area, composed of spindle cells and bizarre cells, formed vague nodules and intersecting fascicles. The spindle cells had deeply eosinophilic cytoplasm and blunt-ended nuclei. The bizarre cells, distributed diffusely throughout the tumour, had pleomorphic features such as epithelioid cells, mononucleated or multinucleated giant cells, and bizarre cells with smudged chromatin. Inflammatory cells were scattered between the tumour cells and clustered in the perivascular area. Mitoses including atypical figures and tumour cell necrosis were not found. Immunohistochemically, the tumour cells stained strongly for smooth muscle actin (SMA) and vimentin, but negatively for Ki-67, p53, cytokeratin, CD34, desmin, S100 protein, HMB45, and myoglobin. The patient has demonstrated no evidence of recurrence or metastasis over a period of 30 months. These immunohistochemical findings, in combination with the absence of mitosis and tumour cell necrosis, the indolent clinical course, and the lack of an infiltrative growth pattern, led to the diagnosis of bizarre leiomyoma. Enzinger and Weiss considered pronounced nuclear pleomorphism to be a kind of degenerative aspect in a long standing lesion. Novak and Anderson referred to multinucleated giant cells with pleomorphic nuclei as those of symplastic type and also concluded that they resulted from degeneration. The vascular alterations of fibrinoid change, inflammation, and the thrombi, unusual findings in leiomyoma, may be important in the genesis of bizarre leiomyoma. Downes and Hart presented a study of 24 bizarre uterine leiomyomas, which came to exactly that conclusion. In approaching our case, our main difficulty was in defining malignant potential. In soft tissue, Billings et al. suggest that tumours with less than 1 mitosis per 50 high power fields (HPF) can be classified as leiomyoma, while tumours with a low mitotic rate (1 to 5 mitoses per 50 HPF) may be considered to be of uncertain malignant potential. However, there may be quite a bit of difficulty in estimation of mitotic rate in bizarre leiomyomas because the details of nuclear contour are modified by degeneration. Yavuz et al. concluded that, in addition to conventional criteria, both the Ki-67 immunostaining index and mast cell count can be used as adjunct findings in the differential diagnosis between leiomyosarcoma and atypical leiomyoma. Thick-walled vessels, an important component of angiomyoma, were not recognised in our case. In addition, we performed reticulin stains to highlight vascular elements, and only small-sized, thin-walled vessels were identified. Malignant melanoma could be excluded by the absence of prominent nucleoli and high mitotic rates, and the negative staining for S100 protein. The lack of high mitotic activity and the negative immunostaining for cytokeratin excluded a sarcomatoid carcinoma. Myofibroblastic tumours mainly consist of spindle cells with a paler and less fibrillary cytoplasm than that of smooth muscle cells. In addition, the myofibroblastic tumour cells do not stain uniformly for SMA, as is often seen in leiomyogenic tumours. In summary, we have discussed the morphological features and differential diagnosis of a case of bizarre leiomyoma of the nasolabial fold. The prognosis and histogenesis of bizarre leiomyoma of the soft tissue remain to be determined by the accumulation of additional cases.