Metastasis Suppressor Genes in Pancreatic Cancer: An Update

Pancreatic cancer, especially pancreatic ductal adenocarcinoma (PDAC), has for long remained a deadly form of cancer characterized by high mortality rates resulting from metastasis to multiple organs. Several factors, including the late manifestation of the disease, partly amplified by lack of efficient screening methods, have hampered the drive to design an effective therapeutic strategy to treat this deadly cancer. Understanding the biology of PDAC progression and identifying critical genes regulating these processes are essential to overcome the barriers toward effective treatment. Metastasis suppressor genes have been shown to inhibit multiple steps in the metastatic cascade without affecting primary tumor formation and are considered to hold promise for treating metastatic cancers. In this review, we catalog the bona fide metastasis suppressor genes reported in PDAC and discuss their known mechanism of action.

CD82 is a marker to isolate β cell precursors from human iPS cells and plays a role for the maturation of β cells

Generation of pancreatic β cells from pluripotent stem cells is a key technology to develop cell therapy for insulin-dependent diabetes and considerable efforts have been made to produce β cells. However, due to multiple and lengthy differentiation steps, production of β cells is often unstable. It is also desirable to eliminate undifferentiated cells to avoid potential risks of tumorigenesis. To isolate β cell precursors from late stage pancreatic endocrine progenitor (EP) cells derived from iPS cells, we have identified CD82, a member of the tetraspanin family. CD82⁺ cells at the EP stage differentiated into endocrine cells more efficiently than CD82^- EP stage cells. We also show that CD82⁺ cells in human islets secreted insulin more efficiently than CD82^- cells. Furthermore, knockdown of CD82 expression by siRNA or inhibition of CD82 by monoclonal antibodies in NGN3⁺ cells suppressed the function of β cells with glucose-stimulated insulin secretion, suggesting that CD82 plays a role in maturation of EP cells to β cells.

Genome-wide in vivo RNAi screen identifies ITIH5 as a metastasis suppressor in pancreatic cancer

The overwhelming majority of pancreatic ductal adenocarcinoma (PDAC) is not diagnosed until the cancer has metastasized, leading to an abysmal average life expectancy (3-6 months post-diagnosis). Earlier detection and more effective treatments have been hampered by inadequate understanding of the underlying molecular mechanisms controlling metastasis. We hypothesized that metastasis suppressors are involved in controlling metastasis in pancreatic cancer. Using an unbiased genome-wide shRNA screen, an shRNA library was transduced into the non-metastatic PDAC line S2-028 followed by intrasplenic injection. Resulting liver metastases were individually isolated from these mice. One liver metastatic nodule contained shRNA for ITIH5 (Inter-alpha-trypsin inhibitor heavy chain 5), suggesting that ITIH5 may act as a metastasis suppressor. Consistent with this notion, metastatic PDAC cell lines had significantly lower protein expression of ITIH5 compared to immortalized pancreatic ductal epithelial cells and non-/poorly-metastatic PDAC cell lines. By manipulating expression of ITIH5 in different PDAC cell lines (over-expression in metastatic, knockdown in non-metastatic) functional and selective regulation of metastasis was observed for ITIH5. Orthotopic tumor growth of PDAC cells was not blocked following orthotopic injection. In vitro ITIH5 over-expression inhibited motility and invasion. Immunohistochemical analysis of a human PDAC tissue microarray revealed that ITIH5 expression inversely correlated with both survival and invasion/metastasis. ITIH5 is, therefore, functionally validated as a PDAC metastasis suppressor and shows promise as a prognostic biomarker.

Overexpression of KAI1/CD82 suppresses in vitro cell growth, migration, invasion and xenograft growth in oral cancer

KAI1/CD82 is a metastatic suppressor gene in human prostate cancer and several other types of cancer in humans. The present study aimed to examine the role of the overexpression of KAI1 in the progression of oral cancer. Human KAI1/CD82 cDNA was transfected into OSCC-15 and 293T cell lines, and its effects on OSCC-15 cell proliferation, invasion and apoptosis were assessed by performing a 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay, Matrigel invasion and Annexin V-FITC staining, respectively. In addition, a xenograft model was used to assess the effect of KAI1/CD82 on the in vivo growth of tumors. The overexpression of KAI1/CD82 inhibited the proliferation and invasion of OSCC-15 cells. It also enhanced the apoptotic rate of the OSCC-15 cells. Furthermore, the overexpression of KAI1/CD82 inhibited tumor growth in the xenograft model. The results demonstrated that the overexpression of KAI1/CD82 significantly inhibited the proliferation and invasion of human oral cancer cells, and inhibited tumor growth in the xenograft model. Therefore, KAI1/CD82 may be considered as a potential therapeutic target in oral cancer.

Tumor dormancy and the role of metastasis suppressor genes in regulating ectopic growth

Metastasis, or tumor growth in an ectopic site, may occur several years after apparently successful treatment of the primary malignancy. Clinical dormancy is seen in a large number of cancer patients, but once growth in an ectopic site initiates, current adjuvant therapies are inadequate and the majority of patients with metastatic disease will die. Many genes may regulate ectopic growth in a secondary site, including a small subset, termed the metastasis suppressor genes. Investigation into this class of genes holds promise in terms of gaining a greater understanding of tumor dormancy and how the process of metastasis may be naturally inhibited. This review will focus on the role of metastasis suppressor genes in tumor dormancy. Insights into the metastatic process from studies of metastasis suppressor genes may lead to novel targets for antimetastatic therapy through drug-induced reactivation of one or more of these genes and/or their respective signaling pathways.

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Current diagnosis and treatment of pancreatic cancer in China

In China, morbidity and mortality for pancreatic cancer differs from that in most Western countries. Pancreatic cancer is the sixth leading cause of death from malignant disease in China, with an overall cumulative 5-year survival rate of 1% to 3%. Pancreatic cancer has the highest incidence in Shanghai (7.21/100,000) and the lowest (0.47/100,000) in the Hunan Province. As in the Western world, the main reason for the poor outcome of patients with pancreatic cancer is the late establishment of the diagnosis. Pancreatic cancer is seldom detected in early disease stages, and until now, the process of cancer initiation, progression, and formation of metastasis is not sufficiently understood. In this article, we reviewed recent data on patients in China with pancreatic cancer and obtained the most updated information on the different aspects of oncologic research, including epidemiology, molecular biology, diagnosis, and treatment.

Surgical management of neoplasms of the ampulla of Vater: local resection or pancreatoduodenectomy and prognostic factors for survival. Surgery. 2004;136:994-1002. [PMID: 15523392 DOI: 10.1016/j.surg.2004.03.010] [Cited by in Crossref: 99] BACKGROUNDNeoplasms of the ampulla of Vater have a better 5-year survival than pancreatic and bile duct neoplasms after resection. This study was performed to analyze the outcome after local resection and pancreatoduodenectomy (PD) and to identify predictive factors for survival.METHODSWe used a prospective database to evaluate 145 patients (1992-2002) with a neoplasm of the ampulla of Vater.RESULTSThe median age of the entire cohort was 66 years. Agreement between preoperative biopsies and definite resection specimen was 58% for invasive adenocarcinoma. Local resection was performed in 25 patients, but the operation was adequate therapy in only 16 patients (64%). Subsequent PD (n=9) was performed in the remaining patients because of an R1 resection. Other patients (n=120) underwent an elective PD. Hospital mortality was 4.0% (1/25) after local resection and 5.0% (6/120) after PD. Multivariate analysis revealed that advanced invasion and nodal status were independent predictive factors for survival. The overall 5-year actuarial survival of patients with adenocarcinoma after PD was 37%.CONCLUSIONSPreoperative biopsies have a poor diagnostic accuracy. Local resection is an adequate surgical treatment for adenomas. In experienced hands, PD is the preferred treatment for patients with adenocarcinoma

BACKGROUND

Neoplasms of the ampulla of Vater have a better 5-year survival than pancreatic and bile duct neoplasms after resection. This study was performed to analyze the outcome after local resection and pancreatoduodenectomy (PD) and to identify predictive factors for survival.

METHODS

We used a prospective database to evaluate 145 patients (1992-2002) with a neoplasm of the ampulla of Vater.

RESULTS

The median age of the entire cohort was 66 years. Agreement between preoperative biopsies and definite resection specimen was 58% for invasive adenocarcinoma. Local resection was performed in 25 patients, but the operation was adequate therapy in only 16 patients (64%). Subsequent PD (n=9) was performed in the remaining patients because of an R1 resection. Other patients (n=120) underwent an elective PD. Hospital mortality was 4.0% (1/25) after local resection and 5.0% (6/120) after PD. Multivariate analysis revealed that advanced invasion and nodal status were independent predictive factors for survival. The overall 5-year actuarial survival of patients with adenocarcinoma after PD was 37%.

CONCLUSIONS

Preoperative biopsies have a poor diagnostic accuracy. Local resection is an adequate surgical treatment for adenomas. In experienced hands, PD is the preferred treatment for patients with adenocarcinoma.

Clinicopathological significance of maspin and Kail expressions in carcinogenesis and progression of gastric cancer

AIM: To investigate the expressions of maspin and Kai1 in gastric cancer and to explore their roles in tumorigenesis and progression of gastric cancer.

METHODS: Normal gastric mucosa (n = 182), gastric dysplasia (n = 69), and gastric cancer (n = 113) were detected for maspin and Kai1 expressions by immunohistochemical methods. The expressions were compared with clinicopathological parameters of the tumor. Relationship between maspin and Kai1 expressions was analyzed as well.

RESULTS: The positive rates of maspin expression were 79.8% (145/182), 75.4% (52/69), and 50.4% (57/113) in normal gastric mucosa, gastric dysplasia, and gastric cancer, while those of Kai1 expression were 81.9% (149/182), 65.2% (49/69), and 58.4% (66/113) in corresponding tissues, respectively. The gastric normal mucosa and dysplasia more frequently expressed maspin than primary gastric cancer did, (P <0.01), while the normal mucosa showed more frequent expression of Kai1 than dysplasia and primary cancer did (P <0.01). Maspin expression significantly related to invasive depth (P = 0.003<0.01), metastasis (P = 0.027<0.05), Lauren's (P = 0.015<0.05) and histological classification (P = 0.024<0.05), but not to tumor size, Borrmann's classification, growth pattern and TNM staging (P >0.05). Kai1 expression significantly related to invasive depth (P = 0.043<0.05), metastasis (P = 0.005<0.01), growth pattern (P = 0.034<0.05), Lauren's classification (P = 0.000<0.01) and histological classification (P = 0.004<0.01), but not to tumor size, Borrmann's classification and TNM staging (P >0.05). Maspin expression was significantly consistent with Kail expression in primary gastric cancer (P = 0.008<0.05).

CONCLUSION: Down-regulated expressions of maspin and Kai1 play an important role in gastric carcinogenesis. They may have inhibitory effects on invasion and metastasis of gastric cancer. Abnormal expressions of maspin and Kai1 might be an objective indicator for pathobiological behaviors of gastric cancer.

Effects of metastasis-suppressor gene KAI1 on viscoelastic properties of hepatocellular carcinoma MHCC97-H cells with high metastatic potential

AIM: To study the effects of metastasis-suppressor gene KAI1 on viscoelastic properties of hepatocellular carcinoma MHCC97-H cells with high metastatic potential.

METHODS: The viscoelastic properties of MHCC97-H cells with high metastatic potential transfected with sense or antisense KAI1 expression plasmid in our previous experiments were measured by means of micropipette aspiration technique.

RESULTS: The elastic coefficients K1, K2 and m of the MHCC97-H cells were significantly higher after transfected with sense KAI1 expression plasmid (P = 0.007), lower after transfected with antisense KAI1 expression plasmid (P = 0.000), and no significantly different after transfected with its control vector pCI-neo without KAI1 gene (P = 0.444), as compared with their paternal MHCC97-H cells.

CONCLUSION: The metastasis-suppressor gene KAI1 may significantly affect the viscoelastic properties of MHCC97-H cells with high metastatic potential. It offers an important clue to study the mechanisms of invasion and metastasis of the malignant tumor.

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Correlation of CT enhancement, tumor angiogenesis and pathologic grading of pancreatic carcinoma

AIM: To study the correlation between pancreatic phase CT enhancement, intratumor microvessel density (MVD) and pathologic grading of pancreatic carcinoma and to evaluate the relationship between the degrees of CT enhancement and malignancy of pancreatic carcinoma.

METHODS: Thirty four patients with pancreatic carcinoma underwent CT scanning before resection. The enhancement degrees and forms of tumor were observed in pancreatic phase. The operative sample was stained with HE and CD34 marked by immunohistochemistry. MVD and histopathological grades of pancreatic carcinoma were examined. CT enhancement of the tumor, MVD counting in hot spot areas of neoplastic parenchymal cells and pathological grades of pancreatic carcinoma were comparatively analyzed.

RESULTS: Highly differentiated pancreatic adenocarcinoma was identified in 16 patients, moderately-differentiated tumor in 7 and poorly-differentiated in 11. Isodensity CT enhancement was demonstrated in 13 cases, slightly low density enhancement in 9, slightly low density enhancement with small cystic lesions in 9 and slightly low density enhancement with large cystic lesions in 3. The counting of MVD with CD34 marked by immunohistochemistry in hot spot areas of neoplastic parenchyma cells was small in 10 cases, medium in 16 and large in 8. The pathological grades correlated well with CT enhancement of the tumor (r = 0.7857, P < 0.001) and with MVD counting of tumor (r = 0.3613, P < 0.05). The CT enhancement of tumor correlated with MVD(r = 0.6768, P < 0.001).

CONCLUSION: There is an obvious and significant correlation between CT enhancement, pathological grades and MVD number in the hot spot areas of tumor. The extent of CT enhancement is inversely proportional to the malignant degree of pancreatic carcinoma, and to the MVD number in the hot spot areas of neoplastic parenchyma. The MVD in the hot spot areas of neoplastic parenchyma cells can also reflect the prognosis of the patients, and is directly proportional to the malignant degree of pancreatic carcinoma.

Relationship between nuclear morphometry, DNA content and resectability of pancreatic cancer

AIM: To investigate the association of nuclear morphometry and DNA content with resectability of pancreatic cancer.

METHODS: A total of 36 patients with pancreatic adenocarcinoma were divided into resectable group and unresectable group. The nuclear morphometry and DNA contents of tumor cells were analyzed by IBAS autoimagine analyzer from paraffin-embedded materials. Localization size, histological type and grade, and clinical stage of the tumor were evaluated. Factors influencing resectability of pancreatic cancer were investigated using stepwise regression analysis.

RESULTS: Statistical significance was found in nuclear DNA content (integrated optical density, IOD) of tumor cells (1.64 ± 0.41 vs 2.96 ± 0.55), DNA ploidy, ages (46.5 ± 5.3 years vs 58.6 ± 0.7 years) and tumor volumes (298.1 ± 101.5 cm³vs 634.7 ± 512.5 cm³) in both groups (P < 0.05), and no difference was found in the nuclear morphometry (P > 0.05). The rates of diploid/tetraploid and aneuploid were 66.7% and 33.3% in resectable group respectively, and 38.9% and 62.1% in unresectable group, respectively (P < 0.05). IOD (X₁₂), ploidy status (X₁₃) and clinical stage (X₃) were radical resectable indicators with statistical significance. The regression equation for resectability was Y = -9.2053 + 3.5428X₁₂ + 2.5390X₁₃ - 2.3001X₃ (RR = 0.8780, P < 0.01).

CONCLUSION: There is a high correlation between resectability of pancreatic cancers and their DNA contents, DNA ploidy status and clinical stage.

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Localization of TRAIL/TRAILR in fetal pancreas

AIM: To observe the localization of TRAIL/TRAIR (DR4, DR5, DcR1, DcR2) in the fetal pancreas.

METHODS: Fetal pancreas of 32 wk of pregnancy were obtained from induced abortions, embedded in paraffin, and 4-μm sections were prepared. The localization of TRAIL/TRAILR in fetal pancreas was investigated by fluorescence immunohistochemical method combined with laser scanning confocal microscopy.

RESULTS: TRAIL immunoreactive cells were mainly located on the periphery of the pancreas islets. There were a few DcR1 and DcR2 positive cells whereas there were no immunoreactive cells of DR4 and DR5 in the pancreas islets. In the acini and the ducts of the exocrine pancreas there were no TRAIL/TRAILR immunoreactive cells.

CONCLUSION: This study not only describes the distribution of TRAIL/TRAILR in the fetal pancreas, but also provides a morphological basis for deducing the function of TRAIL/TRAILR in pancreas, suggesting that in normal pancreatic islets, the pancreatic cells are resistant towards apoptosis too.

K-ras gene mutation in the diagnosis of ultrasound guided fine-needle biopsy of pancreatic masses

AIM: To investigate the utility of K-ras mutation analysis of ultrasound guided fine-needle aspirate biopsy of pancreatic masses.

METHODS: Sixty-six ultrasound guided fine-needle biopsies were evaluated by cytology, histology and K-ras mutation. The mutation at codon 12 of the K-ras oncogene was detected by artificial restriction fragment length polymorphisms using BstN I approach.

RESULTS: The presence of malignant cells was reported in 40 of 54 pancreatic carcinomas and K-ras mutations were detected in 45 of the 54 FNABs of pancreatic carcinomas. The sensitivity of cytology and K-ras mutation were 74% and 83%, respectively. The speciality of cytology and K-ras mutation were both 100%. The sensitivity and speciality of K-ras mutation combined with cytology were 83% and 100%, respectively.

CONCLUSION: High diagnostic accuracy with acceptable discomfort of FNAB make it useful in diagnosis of pancreatic carcinoma. Ultrasound guided fine-needle biopsy is a safe and feasible method for diagnosing pancreatic cancer. Pancreatic carcinoma has the highest K-ras mutation rate among all solid tumors. The mutation rate of K-ras is about 80%-100%. The usage of mutation of codon 12 of K-ras oncogene combined with cytology is a good alternative for evaluation of pancreatic masses.

Relationship between expression of nm23H1 gene and in vivo and in vitro invasive capacity of gastric cancer cells

AIM: To explore the relationship between the expression of nm23H1 gene and the in vivo and in vitro. invasive capacity of gastric cancer cells

METHODS: The invasive capacity of gastric cancer cell in vitro was determined by Boyden chamber method. And the expressions of nm23H1 in gene and protein level were measured by Northern Blot, RT-PCR and immunohistochemical method in gastric cancer cell lines, respectively.

RESULTS: The order of the invasive capacity of gastric cancer cell lines were: MKN45, being the highest(33.1±5.23, P<0.01); BGC823(15.8±2.7) and MKN1(14.1±4.5), the moderate(there was no significant difference between them, P>0.05), and GT3TKB(6.3±2.5), the lowest(P<0.01). The expression of nm23H1 gene was negatively correlated with the in vivo invasive capacity of gastric cancer cell lines, and also negatively correlated with the in vitro invasive capacity of gastric cancer cell lines of MKN45, BGC823 and GT3TKB. But there was no relationship between the expression of nm23H1 gene and the invasive capacity of MKN1 in vitro.

CONCLUSION: The expression of nm23H1 gene is of great significance in evaluating the in vivo and in vitro invasive capacity of gastric cancer cell lines.

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