Abnormal expression of p16(INK4a), cyclin D1, cyclin-dependent kinase 4 and retinoblastoma protein in gastric carcinomas

Prognosis and survival study in patients with gastric adenocarcinoma and its relationship with pRb expression alteration: A retrospective IHC-based study

Background and Objective

Among cancers, gastric cancer has the fifth highest incidence worldwide and is the third most common mortality factor, which may have been due to inadequate knowledge of its molecular pathogenesis. The retinoblastoma gene (RB1), a tumor suppressor gene, may have a role in gastric cancer. This research aims to assess Rb expression as a prognostic marker to obtain more insight regarding gastric cancer.

Methods

This retrospective analytical study was done on 61 patients (45 males and 16 females) with gastric adenocarcinoma admitted from 2010 to 2012 in Shahid Sadoughi and Mortaz hospitals, Yazd, Iran. Demographic data, including age, gender, clinical signs and symptoms, and pathology reports, were retrieved from patients' hospital folders. Then, the altered Retinoblastoma gene expression was evaluated by immunohistochemistry studies. Acquired data were analyzed by SPSS software v.16. p < 0.05 was statistically considered meaningful.

Results

In this study, the ratio of men to women was higher (2.81:1), and the mean age of patients was 62.44 years. About 90.2% of patients died during the study. There was no meaningful relationship between the presence of pRb, the intensity of staining, the percentage of staining with patients' age, gender, tumor grading, and survival rate (p > 0.05). There was only a meaningful relationship between the grade of tumors and survival rate (p = 0.039).

Conclusion

Altered pRB expression is not common in gastric cancer and does not impact the survival and grading of tumors. Poorly differentiated tumors had an ominous outcome with the lowest survival time.

The Role and Clinical Implications of the Retinoblastoma (RB)-E2F Pathway in Gastric Cancer

Gastric cancer is the most common malignant tumor in the digestive tract, with very high morbidity and mortality in developing countries. The pathogenesis of gastric cancer is a complex biological process mediated by abnormal regulation of proto-oncogenes and tumor suppressor genes. Although there have been some in-depth studies on gastric cancer at the molecular level, the specific mechanism has not been fully elucidated. RB family proteins (including RB, p130, and p107) are involved in cell cycle regulation, a process that largely depends on members of the E2F gene family that encode transcriptional activators and repressors. In gastric cancer, inactivation of the RB-E2F pathway serves as a core transcriptional mechanism that drives cell cycle progression, and is regulated by cyclins, cyclin-dependent kinases, cyclin-dependent kinase inhibitors, p53, Helicobacter pylori and some other upstream molecules. The E2F proteins are encoded by eight genes (i.e. E2F1 to E2F8), each of which may play a specific role in gastric cancer. Interestingly, a single E2F such as E2F1 can activate or repress transcription, and enhance or inhibit cell proliferation, depending on the cell environment. Thus, the function of the E2F transcription factor family is very complex and needs further exploration. Importantly, the presence of H. pylori in stomach mucosa may affect the RB and p53 tumor suppressor systems, thereby promoting the occurrence of gastric cancer. This review aims to summarize recent research progress on important roles of the complex RB-E2F signaling network in the development and effective treatment of gastric cancer.

Upregulation of family with sequence similarity 83 member D expression enhances cell proliferation and motility via activation of Wnt/β-catenin signaling and predicts poor prognosis in gastric cancer

Background/aims

Gastric cancer (GC) is the third most common cause of cancer-related death worldwide. The molecular mechanisms underlying the progression of gastric cancer are still not fully elucidated. In this study, we focused on exploring the role of family with sequence similarity 83, member D (FAM83D) in gastric cancer progression.

Methods

The expression of FAM83D in GC tissues was detected by immunohistochemistry (IHC) staining. FAM83D knockdown or overexpression were constructed in AGS and SGC-7901 cells with two distinct siRNA duplexes and lentivirus infection, respectively, to explore the role of FAM83D in gastric cancer progression. Nude mouse xenograft assay was used to further explore the role of FAM83D in tumorigenesis in vivo.

Results

We found that FAM83D mRNA and protein levels were higher in human GC tumor tissues and in GC cell lines, compared with the adjacent normal tissues and non-malignant gastric epithelial cell lines, respectively, and that higher FAM83D expression was correlated with worse overall survival (p<0.0001) and disease-free survival (p<0.0001) in GC patients. Additionally, our results showed that FAM83D overexpression significantly enhanced the proliferation, clonogenicity, and motility of GC cells, whereas FAM83D depletion caused a dramatic increase in the number of cells arrested at the G1 phase of the cell cycle. Consistent with these findings from in vitro experiment, our data also indicated that FAM83D knockdown significantly repressed GC tumor growth in vivo. Furthermore, we demonstrated that FAM83D depletion was associated with reduced Wnt/β-catenin signaling.

Conclusions

This study suggested that FAM83D overexpression enhanced the proliferation, clonogenicity, and motility of GC cells by activating Wnt/β-catenin signaling, and FAM83D may be a promising diagnostic and therapeutic target for human GC.

RN181 is a tumour suppressor in gastric cancer by regulation of the ERK/MAPK-cyclin D1/CDK4 pathway

RN181, a RING finger domain-containing protein, is an E3 ubiquitin ligase. However, its biological function and clinical significance in cancer biology are obscure. Here, we report that RN181 expression is significantly down-regulated in 165 tumour tissues of gastric carcinoma (GC) versus adjacent non-tumour tissues, and inversely associated with tumour differentiation, tumour size, clinical stage, and patient's overall survival. Alterations of RN181 expression in GC cells by retrovirus-transduced up-regulation and down-regulation demonstrated that RN181 functions as a tumour suppressor to inhibit growth of GC in both in vitro culture and in vivo animal models by decreasing tumour cell proliferation and increasing tumour cell apoptosis. Cell cycle analysis revealed that RN181 controls the cell cycle transition from G1 to S phase. Mechanistic studies demonstrated that RN181 inhibits ERK/MAPK signalling, thereby regulating the activity of cyclin D1-CDK4, and consequently controlling progression in the cell cycle from G1 to S phase. Restoring CDK4 in GC cells rescued the inhibitory phenotype produced by RN181 in vitro and in vivo, suggesting a dominant role of CDK4 in control of the tumour growth by RN181. Importantly, RN181 expression is inversely correlated with the expression of cyclin D1 and CDK4 in GC clinical samples, substantiating the role of the RN181-cyclin D1/CDK4 pathway in control of the tumour growth of GC. Our results provide new insights into the pathogenesis and development of GC and rationale for developing novel intervention strategies against GC by disruption of ERK/MAPK-cyclin D1/CDK4 signalling. In addition, RN181 may serve as a novel biomarker for predicting clinical outcome of GC. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Gastric hepatoid adenocarcinomas are a genetically heterogenous group; most tumors show chromosomal instability, but MSI tumors do exist

The Cancer Genome Atlas Research Network classified gastric adenocarcinoma into four molecular subtypes: (1) Epstein-Barr virus-positive (EBV), (2) microsatellite-instable (MSI), (3) chromosomal instable (CIN), and (4) genomically stable (GS). The molecular subtypes of gastric hepatoid adenocarcinomas are still largely unknown. We analyzed 52 hepatoid adenocarcinomas for the expression of surrogate markers of molecular subtypes (MLH1, p53, and EBER in situ hybridization) and some biomarkers (p21, p16, Rb, cyclin D1, cyclin E, β-catenin, Bcl-2, IMP3, ARID1A and HER2), and mutations of TP53, CTNNB1, KRAS, and BRAF. We analyzed 36 solid-type poorly differentiated adenocarcinomas as a control group. Hepatoid adenocarcinomas were categorized as follows: EBV group (EBER-positive), no cases (0%); MSI group (MLH1 loss), three cases (6%); "CIN or GS" (CIN/GS) group (EBER-negative, MLH1 retained), 49 cases (94%). In the CIN/GS group, most of the tumors (59%) had either p53 overexpression or TP53 mutation and a coexisting tubular intestinal-type adenocarcinoma component (90%), suggesting that most hepatoid adenocarcinomas should be categorized as a true CIN group. Hepatoid adenocarcinomas showed relatively frequent expressions of HER2 (score 3+/2+: 21%/19%). Hepatoid adenocarcinomas showed shorter survival, more frequent overexpressions of p16 (67%) and IMP3 (98%) than the control group. None of hepatoid adenocarcinomas had KRAS or CTNNB1 mutations except for one case each, and no hepatoid adenocarcinomas had BRAF mutation. In conclusion, gastric hepatoid adenocarcinomas are a genetically heterogenous group. Most hepatoid adenocarcinomas are "CIN," but a small number of hepatoid adenocarcinomas with MSI do exist. Hepatoid adenocarcinomas are characterized by overexpressions of p16 and IMP3.

Oxidative stress and cell cycle arrest induced by short-term exposure to dustfall PM2.5 in A549 cells

It was reported that in vitro short-term exposure to PM_2.5 caused different lung diseases through inflammatory response, immune toxicity, oxidative stress, and genetic mutations. However, the complex molecular biological mechanism for its toxicity had not been fully elucidated. Therefore, the present study investigated the cytotoxicity, oxidative damage, mitochondria damage, apoptosis, and cell cycle arrest of NX and QH PM_2.5 in A549 cells. Further, cell cycle arrest-related gene levels in PM_2.5-induced A549 cells were also detected. Our results suggested that PM_2.5 reduced the cell viability in A549 cells. Simultaneously, excessive ROS decreased MMP levels and damaged mitochondrial membrane integrity and induced mitochondrial oxidative damage through the oxygen-dependent killer route, resulting in mitochondrial damage and cell apoptosis. Besides, the results also showed that PM_2.5 induced A549 cell cycle alteration in G2/M phase after co-culture for 24 h. G2/M phase arrest was induced by upregulation of p53 and p21 and downregulation of CDK1 mRNA expression. In addition, lncRNA Sox2ot might play an important role as the specific oncogenes and it participated in G2/M phase arrest by regulating the expression of EZH₂.

Network Pharmacology-Based Approach to Investigate the Mechanisms of Hedyotis diffusa Willd. in the Treatment of Gastric Cancer

BACKGROUND

Hedyotis diffusa Willd. (HDW) is one of the renowned herbs often used in the treatment of gastric cancer (GC). However, its curative mechanism has not been fully elucidated.

OBJECTIVE

To systematically investigate the mechanisms of HDW in GC.

METHODS

A network pharmacology approach mainly comprising target prediction, network construction, and module analysis was adopted in this study.

RESULTS

A total of 353 targets of the 32 bioactive compounds in HDW were obtained. The network analysis showed that CA isoenzymes, p53, PIK3CA, CDK2, P27Kip1, cyclin D1, cyclin B1, cyclin A2, AKT1, BCL2, MAPK1, and VEGFA were identified as key targets of HDW in the treatment of GC. The functional enrichment analysis indicated that HDW probably produced the therapeutic effects against GC by synergistically regulating many biological pathways, such as nucleotide excision repair, apoptosis, cell cycle, PI3K/AKT/mTOR signaling pathway, VEGF signaling pathway, and Ras signaling pathway.

CONCLUSIONS

This study holistically illuminates the fact that the pharmacological mechanisms of HDW in GC might be strongly associated with its synergic modulation of apoptosis, cell cycle, differentiation, proliferation, migration, invasion, and angiogenesis.

Characterization of oncogene suppressor marker expression in patients with submucosal gastric carcinoma

The aim of the present study was to determine the clinical significance of p53 and p21^ras p21^wafl, p27^kip1 and p16^ink4a expression in cases of early gastric cancer. A total of 81 patients who had undergone gastrectomy with D2 lymphadenectomy between 1971 and 2004 were retrospectively investigated. The immunohistochemical expression of p21^ras, p53, p21^waf1/cip1, p27^kip1 and p16^ink4a in the tissues was evaluated. In normal, metaplastic and tumoral mucosa, p53 was positive in 53, 87.3, and 87.1% of the cases, respectively. In the same tissues, p21^ras was positivE in 85.3, 86 and 96.8%, respectively. Positivity FOR p16^ink4a was DETECTED IN 46.3, 91.1 and 86% OF THE CASES, respectively, WHEREAS p27^kip1 WAS positiVE IN 60, 94.7 and 95.3%, and p21^wafl/cip1 WAS positivE IN 32.4, 72.7 and 71.4% OF THE CASES, respectively. All THE tumors WERE positive for p53. Tumors with lymph node invasion presented WITH OVERexpression (+4) of p53 in 47% of the cases VS. 17% OF patients who DID not HAVE lymph node involvement. THEREFORE, higher expression of p53, p21^ras and p21^wafl/cip1 IN the tumor exhibited a statistically significant association with lymph node involvement.

Tspan5 is an independent favourable prognostic factor and suppresses tumour growth in gastric cancer

Tetraspanins are believed to interact with specific partner proteins forming tetraspanin-enriched microdomains and regulate some aspects of partner protein functions. However, the role of Tspan5 during pathological processes, particularly in cancer biology, remains unknown. Here we report that Tspan5 is significantly downregulated in gastric cancer (GC) and closely associated with clinicopathological features including tumour size and TNM stage. The expression of Tspan5 is inversely correlated with patient overall survival and is an independent prognostic factor in GC. Upregulation of Tspan5 in tumour cells results in inhibition of cell proliferation and colony formation in vitro and suppression of xenograft growth of GC by reducing tumour cell proliferation in vivo. Thus, Tspan5 functions as a tumour suppressor in stomach to control the tumour growth. Mechanistically, Tspan5 inhibits the cell cycle transition from G1-S phase by increasing the expression of p27 and p15 and decreasing the expression of cyclin D1, CDK4, pRB and E2F1. The correlation of Tspan5 expression with the expression of p27, p15, cyclin D1, CDK4, pRB and E2F1 in vivo are also revealed in xenografted tumours. Reconstitution of either cyclin D1 or CDK4 in Tspan5-overexpressing GC cells rescues the inhibitory phenotype produced by Tspan5, suggesting that cyclin D1/CDK4 play a dominant role in mediating the suppression of tumour growth by Tspan5 in GC. Our results suggest that Tspan5 may serve as a prognostic biomarker for predicting outcome of GC patients and provide new insights into the pathogenesis of GC and rational for the development of clinical intervention strategies against GC.

Function of cell-cycle regulators in predicting silent pituitary adenoma progression following surgical resection

The present study investigated the use of cell-cycle regulators for predicting the progression of silent pituitary adenoma (SPA) following surgical resection, via immunohistochemical analysis of tumor samples obtained by surgical resection. The medical records of patients diagnosed with SPA between January 2000 and December 2013 in the Samsung Changwon Hospital, Sungkyunkwan University School of Medicine (Changwon, South Korea) were reviewed. Immunohistochemical staining was performed on sections of the archived, paraffin-embedded tissues obtained by surgery, with all tissues stained for cell-cycle regulatory proteins p16, p15, p21, cyclin-dependent kinase (CDK)4, CDK6, retinoblastoma protein (pRb) and cyclin D1, as well as E3 ubiquitin-protein ligase mib1 (MIB-1) antigen and p53. The primary end-point was to investigate the expression of cell-cycle regulatory proteins in SPA. The secondary end-point was to estimate the progression-free survival of patients with SPA following surgical resection and to identify its association with the expression of cell-cycle regulatory proteins. Of the 127 SPA samples, 44 (34.6%) were from patients with progression during a mean follow-up period of 62.4 months (range, 24.2–118.9 months). Immunohistochemical overexpression was identified in 61 samples (48.0%) for p16, 38 samples (29.9%) for p15, 19 samples (15.0%) for p21, 49 samples (38.6%) for CDK4, 17 samples (13.4%) for CDK6, 57 samples (44.9%) for pRb and in 65 samples (51.2%) for cyclin D1. Multivariate analysis revealed that null cell adenoma [95% confidence interval (CI), 0.276–0.808], somatotroph SPAs (95% CI, 1.296–3.121), corticotroph SPAs (95% CI, 1.811–4.078), pluripotent SPAs (95% CI, 2.264–5.194), decreased expression of p16 (95% CI, 2.724–5.588), overexpression of pRb (95% CI, 2.557–5.333), cyclin D1 (95% CI, 1.894–4.122) and MIB-1 (95% CI, 1.561–4.133), increased mitotic index (95% CI, 1.228–4.079), increased p53 expression (95% CI, 1.307–4.065) and invasion into the cavernous sinus (95% CI, 3.842–7.502) predicted SPA progression following resection. The results of the present study suggested that specific cell-cycle regulators, including p16, cyclin D1 and pRb, were associated with SPA progression.

A case of rectal neuroendocrine carcinoma in a patient with long-standing ulcerative colitis involving alterations of the p16-Rb pathway

The patient was a 54-year-old male who had been suffering from extensive ulcerative colitis (UC) for 17 years. Colonoscopy revealed an elevated lesion in the affected rectum, and its biopsy demonstrated neuroendocrine carcinoma (NEC). The surgical specimen obtained on laparoscopic high anterior resection showed extensive active inflammatory and dysplastic lesions and three grossly visible multifocal malignant lesions: a polypoid fungating tumor of NEC (type 1, 20 mm in diameter, pT3) that had been preoperatively noticed, a polypoid fungating tumor of adenocarcinoma (type 1, 22 mm, pT2) and a protruded sessile polypoid tumor (0-Is, 5 mm, pTis) of adenocarcinoma. The NEC was adjacently accompanied by dysplasia-carcinoma sequential lesions and showed a diffuse immunohistochemical overexpression of p53 and p16 proteins and the loss of Rb with no abnormal immunohistochemical staining of microsatellite instability markers and no KRAS mutations. Fifteen months later, the patient showed liver metastasis from the NEC component, followed by bone and spinal metastasis; he died 22 months after the initial diagnosis. A rare case of lethal NEC arising from long-standing extensive UC was reported. The NEC appeared to be UC-related, not incidental, and complicated by progression from dysplasia to carcinoma involving alterations of the p16-Rb pathway.

miR-218 suppresses gastric cancer cell cycle progression through the CDK6/Cyclin D1/E2F1 axis in a feedback loop

Studies in several cancers have suggested that miR-218 has anti-tumor activities, but its function is yet to be elucidated. In this study, we investigated the regulation and function of miR-218 (miR-218-5p) in the cell cycle progression of gastric cancer (GC). We found that miR-218 could suppress proliferation of gastric cancer cells, induce cell cycle arrest at the G1 phase and inhibit tumor growth and metastasis in vivo. We also demonstrated that miR-218 specifically targeted the 3'-UTR regions of CDK6 and cyclin D1 and inhibited the expression of these molecules, which in turn repressed the pRb/E2F1 signaling pathway. Overexpression of CDK6 and Cyclin D1 reversed miR-218-mediated inhibition of pRB/E2F1 signaling and attenuated the miR-218-induced cell cycle arrest. More importantly, miR-218 expression was significantly reduced and inversely correlated with the levels of CDK6 and Cyclin D1 in gastric cancer tissues. Decreased miR-218 expression was also correlated with advanced clinical stage, lymph node metastasis, and poor prognosis in gastric cancer patients. Furthermore, we showed that miR-218 expression was directly activated by E2F1 through the transactivation of miR-218 host genes, SLIT2 and SLIT3, revealing a negative feedback regulation of miR-218 expression. Taken together, our results describe a regulatory loop miR-218-CDK6/CyclinD1-E2F1 whose disruption may contribute to cell cycle progression in gastric cancer and indicate the potential application of miR-218 in cancer therapy.

TRIM24 promotes the aggression of gastric cancer via the Wnt/β-catenin signaling pathway

Tripartite motif-containing 24 (TRIM24) is important in tumor development and progression. However, the role of TRIM24 in gastric cancer (GC) and the mechanisms underlying the dysregulated expression of TRIM24 remain to be fully elucidated. In the present study, it was found that TRIM24 was frequently overexpressed in GC cell lines and tissues compared with normal controls, as determined by western blotting and immunohistochemical staining. The high nuclear expression of TRIM24 was correlated with the depth of invasion (P=0.007), tumor-node-metastasis stage (P=0.005), and lymph node metastasis (P=0.027), and shorter overall survival rates (P=0.010) in patients with GC. Small interfering RNA-mediated knockdown of TRIM24 inhibited cell proliferation, colony formation, migration, invasion and the nuclear accumulation of β-catenin, and it delayed cell cycle progression and induced apoptosis. In addition, the expression of TRIM24 was positively correlated with that of β-catenin in GC tissues. TRIM24 knockdown decreased the expression of Wnt/β-catenin target genes, whereas the activation of Wnt/β-catenin signaling by lithium chloride reversed the effects of TRIM24 knockdown. Taken together, these data suggested that TRIM24 was a prognostic or potential therapeutic target for patients with GC and was important in the activation of the Wnt/β-catenin pathway during the progression of GC.

MicroRNA-155 expression inversely correlates with pathologic stage of gastric cancer and it inhibits gastric cancer cell growth by targeting cyclin D1

PURPOSE

MicroRNAs (miRs) have been frequently reported dysregulating in tumors and playing a crucial role in tumor development and progression. However, the expression of miR-155 and its role in gastric cancer (GC) are still obscure.

METHODS

qRT-PCR was applied to detect miR-155 expression in 60 matched GC samples and four GC cell lines, and the relationship between miR-155 levels and clinicopathological features of GC was analyzed. Next, the effects of miR-155 on GC cell growth were evaluated by gain- and loss-of-function analysis. Finally, the target gene(s) of miR-155 in GC cells were explored.

RESULTS

Our results revealed that miR-155 levels were significantly lower in both GC tissues and GC cell lines than in their normal controls, and its expression inversely correlated with tumor size and the pathologic stage. Moreover, our study showed that enforced expression of miR-155 impaired GC cell proliferation, promoted G1 phase arrest and induced apoptosis in vitro. In addition, we identified cyclin D1 as the direct target of miR-155, and knockdown of cyclin D1 partially phenocopied the role of miR-155 in GC cells.

CONCLUSIONS

Our findings suggest that miR-155 may act as a potential diagnostic marker for early-stage GC and may represent a novel therapeutic target for GC treatment.

Dysregulation of the Rb pathway in recurrent pleomorphic adenoma of the salivary glands

Pleomorphic adenoma (PA) is the most common salivary gland neoplasm, and while mostly benign, recurrences (RPA) and malignant transformation to carcinoma ex-PA (CXPA) do occur. Cell cycle proteins important in its tumorigenesis have been studied as markers for PA with a high risk of RPA or CXPA. The aim of the present study was to investigate cell cycle markers p-16, cyclin D1, CDK4, E2F, and retinoblastoma (Rb) in this context. Expression of p16, cyclin D1, E2F, CDK4, and Rb was studied by immunohistochemistry in 24 cases of PA, 21 of RPA, and 2 of CXPA. The presence of HPV was assessed by in situ hybridization. Immunostaining for p16 and cyclin D1 was negative or weakly positive in most cases of PA while strongly positive in the majority of RPA and both CXPA cases. Staining for Rb and CDK4 was either negative or weakly positive in PA, RPA, and CXPA. Expression of E2F was stronger in RPA and CXPA than in PA. Nuclear reactivity for HPV was not observed in any case. In conclusion, the strong staining for p16, cyclinD1, and E2F in RPA and CXPA, while weak or negative in PA, suggests that these proteins might be involved in recurrence and malignant transformation of PA.

Anti-proliferation effects and molecular mechanisms of action of tetramethypyrazine on human SGC-7901 gastric carcinoma cells

AIM

To investigate the effects of tetramethypyrazine (TMP) on proliferation and apoptosis of the human gastric carcinoma cell line 7901 and its possible mechanism of action.

METHODS

The viability of TMP-treated 7901 cells was measured with a 3-(4, 5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT) and cell apoptosis was analyzed by flow cytometry. The distribution of cells in different phases of cell cycle after exposure of TMPs was analyzed with flow cytometry. To investigate the molecular mechanisms of TMP-mediated apoptosis, the expression of NF-xBp65, cyclinD1 and p16 in SGC-7901 cells was analyzed by reverse transcription- polymerase chain reaction (RT-PCR) and western blotting.

RESULTS

TMP inhibited the proliferation of human gastric carcinoma cell line 7901 in dose and time dependent manners. Cell growth was suppressed by TMP at different concentrations (0.25, 0.5, 1.0, 2.0 mg/ml), the inhibition rate is 0.46%, 4.36%, 14.8%, 76.1% (48h) and 15.5%, 18.5%, 41.2%, 89.8% (72h) respectively. When the concentration of TMPs was 2.0mg/ml, G1-phase arrest in the SGC-7901 cells was significant based on the data for cell cycle distribution. RT-PCR demonstrated that NF-xBp65 and cyclin D1 mRNA expression was significantly down-regulated in 7901 cells treated with 2.0 mg/ml TMP for 72h (p<0.05), while the p16 mRNA level was up-regulated (p<0.05). The protein expression of NF-xBp65 and cyclin D1 decreased gradually with the increase in TMP concentration, compared with control cells (p<0.05), while expression of protein p16 was up-regulated (p<0.01).

CONCLUSION

TMP exhibits significant anti-proliferative and pro-apoptotic effects on the human gastric carcinoma cell line SGC-7901. NF-xBp65, cyclinD1 and p16 may also play important roles in the regulation mechanisms.

1-butyltryptophan inhibits cell proliferation, migration, and invasion through the Akt pathway in human gastric cancer cells

We have previously demonstrated that novel 1-alkyl-tryptophan analogs 1-butyltryptophan (1-BT) can serve as a potential antitumor agent. However, the molecular mechanisms of 1-BT on cancer cells remain to be elucidated. The effect of 1-BT on cell proliferation was detected by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay and clone formation assay in SGC7901 and AGS cells. Cell cycle was determined by flow cytometry. Cell migration and invasion was determined by wound healing assay and transwell assay. The expression of cyclin-dependent kinase 4 (CDK4), cyclin D1, p16, PCNA, phosphorylated Akt, total Akt, phosphorylated ERK1/2, and total ERK1/2 was examined using Western blotting. Our data demonstrated that 1-BT inhibited cell proliferation in a dose- and time-dependent manner by the downregulation of expression of cyclin D1 and CDK4 and by the upregulation of p16 expression. The inhibition of cell growth was also demonstrated by cell cycle arrest at the G1/S phase. Furthermore, 1-BT inhibited cell migration and invasion in SGC7901 cells. In addition, we found that phosphorylated Akt was suppressed in 1-BT treated SGC7901 cells. Overexpression of activated Akt reversed the effects of 1-BT on cell migration and invasion in SGC7901 cells. These results indicated that 1-BT inhibited gastric cancer cells proliferation and migration through the Akt pathway, which has the potential clinical significance in the prevention and treatment of gastric cancer.

Neoplasms arising in large gastric hyperplastic polyps: endoscopic and pathologic features

BACKGROUND

Little is known about gastric neoplasms arising from hyperplastic polyps (HPs).

OBJECTIVE

To investigate the risk factors associated with neoplasms within HPs and to evaluate the role of alterations of the p16-cyclin D1-pRb pathway in the malignant transformation of HPs.

DESIGN

Retrospective, case-control study.

SETTING

Tertiary-care center.

PATIENTS

Between May 1995 and January 2011, a total of 809 HPs >1 cm were investigated. Associated neoplasms were present in 30 HPs (case group); 30 HPs without neoplasms were selected as a control group.

INTERVENTIONS

Gastric polypectomy.

MAIN OUTCOME MEASUREMENTS

The risk factors associated with neoplasms within HPs and immunohistochemical expression of p16, cyclin D1, p53, and Ki-67 between case and control groups.

RESULTS

Of the 809 HPs, 15 had associated dysplasia, and 15 had carcinoma. Multivariate analysis showed that neoplasm was associated with patient age (odds ratio [OR] 1.159; 95% confidence interval [CI], 1.243-2.044; P < .001), polyp size (OR 1.103; 95% CI, 1.055-1.152; P < .001), and polyp lobulation (OR 4.549; 95% CI, 1.759-11.0766; P < .001) but not with location, multiplicity, intestinal metaplasia, growth pattern, or Helicobacter pylori infection. Loss of p16 expression and high Ki-67 expression were observed in dysplastic areas of HPs compared with the control group (p16 = 14.3% vs 60%; P = .001, Ki-67 = 60.7% vs 36.7%; P < .001). However, no significant differences were found in nondysplastic areas in both groups.

LIMITATIONS

Single-center, retrospective study.

CONCLUSION

HPs >1 cm may indicate the presence of neoplasms. Loss of p16 and high Ki-67 expression may be markers of HP-associated dysplasia.

Results of immunohistochemical staining of cell-cycle regulators: the prediction of recurrence of functioning pituitary adenoma

OBJECTIVE

This study was undertaken primarily to investigate the possible prognostic values of several cell-cycle regulators for the prediction of functioning pituitary adenoma (FPA) recurrence after surgical resection by immunohistochemically analyzing tumor samples obtained by surgical resection.

METHODS

The medical records of the patients with FPA diagnosed from January 2000 to December 2009 at the Department of Neurosurgery at Samsung Changwon Hospital and Dong-A University Medical Center were selected. Immunohistochemical staining was performed on archived paraffin-embedded tissues obtained by surgical resection for adenohypophysial cells, cell-cycle regulatory proteins (p16, p15, p21, cyclin-dependent kinase [CDK] 4 and 6, phosphorylated retinoblastoma [pRB] protein, and cyclin D1), MIB-1 antigen, and p53.

RESULTS

Of the 174 FPAs, 62 (35.6%) recurred during follow-up period (mean duration 62.4 months, range 24.2-118.9 months). Immunohistochemically, overstaining for p16 in 89 samples (51.1%), p15 in 27 samples (15.5%), p21 in 20 samples (11.5%), CDK4 in 54 samples (31.0%), CDK6 in 18 samples (10.3%), pRB protein in 69 samples (39.7%), and cyclin D1 in 87 samples (50.0%). Multivariate analysis using the Cox proportional hazard regression model showed that invasion into cavernous sinus (hazard ratio [HR] of 4.02; P < 0.001), immunohistochemical normostaining for p16 (HR of 3.16; P < 0.001), immunohistochemical overstaining for pRB protein (HR of 2.45; P = 0.008), cyclin D1 (HR of 2.13; P = 0.029), MIB-1 antigen (HR of 2.74; P = 0.002), and p53 (HR of 2.21; P = 0.002), predicted the recurrence of FPA after surgical resection.

CONCLUSIONS

Our findings indicate that p16, pRB protein, and cyclin D1 are associated with recurrence FPA after surgical resection.

Metallothionein 2A inhibits NF-κB pathway activation and predicts clinical outcome segregated with TNM stage in gastric cancer patients following radical resection

Background

Metallothionein 2A (MT2A) as a stress protein, plays a protective role in gastric mucosal barrier. Its role in the development of gastric cancer (GC) is unclear. The mechanism of MT2A will be investigated in gastric tumorigenesis.

Methods

MT2A expression was detected in 973 gastric specimens. The biological function was determined through ectopic expressing MT2A in vitro and in vivo. The possible downstream effectors of MT2A were investigated in NF-κB signaling. The protein levels of MT2A, IκB-α and p-IκB-α (ser32/36) expression were analyzed in a subset of 258 patients by IHC staining. The prognostic effects of MT2A, status of IκB-α and TNM stage were evaluated using the Kaplan-Meier method and compared using the log-rank test.

Results

Decreased MT2A expression was detected in cell lines and primary tumors of GC. In clinical data, loss of MT2A (MT2A + in Normal (n =171, 76.0%); Intestinal metaplasia (n = 118, 50.8%); GC (n = 684. 22.4%, P < 0.001)) was associated with poor prognosis (P < 0.001), advanced TNM stage (P = 0.05), and down-regulation of IκB-α expression (P < 0.001). Furthermore, MT2A was the independent prognostic signature segregated from the status of IκB-α and pathological features. In addition, MT2A inhibited cell growth through apoptosis and G2/M arrest, which negatively regulated NF-κB pathway through up-regulation of IκB-α and down-regulation of p-IκB-α and cyclin D1 expression.

Conclusions

MT2A might play a tumor suppressive activity through inhibiting NF-κB signaling and may be a prognostic biomarker and potential target for individual therapy of GC patients.

The incidence and prognostic value of HER2 overexpression and cyclin D1 expression in patients with gastric or gastroesophageal junction adenocarcinoma in Israel

Human epidermal growth factor 2 (HER2) positivity rates for gastric or gastroesophageal junction (GEJ) adenocarcinoma have been reported at 15-25%. Cyclin D1 (BCL1) is a non-specific proliferative marker. The prognostic significance of HER2 and cyclin D1 is inconclusive, with contradictory data. The aim of this study was to evaluate the incidence of HER2 overexpression in gastric or GEJ patients. The presence of a possible correlation between HER2 status and cyclin D1 staining was assessed; both were evaluated as prognostic markers for survival. The clinical data and histological specimens of 150 consecutive patients diagnosed with gastric or GEJ adenocarcinoma, and treated at our hospital from June 2005 to March 2009, were analyzed. Pathological specimens were immunohistochemically stained for HER2. Immunoreactivity was determined according to the scoring system for gastric carcinoma. Cyclin D1 immunoreactivity was also tested. The results demonstrated that HER2 was positive in 14/150 (9.3%) patients. HER2-positive (HER2(+)) and HER2-negative (HER2(-)) patients did not differ significantly with regard to other clinicopathological parameters. In a multivariate analysis, HER2 positivity was revealed to be a poor prognosis variable (P=0.046; 95% CI, 1.03-3.58). In patients with non-metastatic disease, median survival was 59 months for HER2(-) and 42 months for HER2+ patients, but this difference was not significant. In patients with metastatic disease, median survival was 9.5 months and 2.5 months for HER2(-) and HER2+ patients, respectively (P=0.041). Cyclin D1 was not idemonstrated to be a prognostic factor and was not associated with HER2 overexpression. The rate of positive HER2 status in the current group of unselected patients with gastric and GEJ adenocarcinoma was relatively low compared with that observed in the literature. Nevertheless, HER2 positivity was associated with a poor prognosis.

Methylation and Expression of Retinoblastoma and Transforming Growth Factor-β1 Genes in Epstein-Barr Virus-Associated and -Negative Gastric Carcinomas

Background. Retinoblastoma (RB) and transforming growth factor-β1 (TGF-β1) are important tumor-related factors. Methods. A series of 30 EBV-associated gastric carcinoma (EBVaGC) and 38 matched EBV-negative gastric carcinoma (EBVnGC) tissues were examined for the promoter methylation of RB by methylation-specific PCR (MSP) method. The expression of RB and TGF-β1 in gastric carcinoma tissues was detected by immunohistochemistry. Results. The methylation rate of RB gene in EBVaGC and EBVnGC was 80.0% (24/30) and 50.0% (19/38), respectively. The difference of RB methylation rate between EBVaGC and EBVnGC was significant (χ² = 6.490, P = 0.011). There was no significant difference for RB expression between EBVaGC (43.3%, 13/30) and EBVnGC (63.2%, 24/38), and also for TGF-β1 between EBVaGC (56.7%, 17/30) and EBVnGC (63.2%, 24/38). RB methylation was not reversely correlated with RB expression in gastric carcinoma tissues (χ² = 2.943, P = 0.086, r = 0.208). RB methylation, loss expression of RB, and TGF-β1 expression were significantly associated with tumor invasion and lymph node metastasis (P < 0.05), but was not associated with sex, age, histological subtype (differentiation status) and tumor location. Conclusions. Methylation of RB is a common event in gastric carcinomas and EBV induces methylation of RB in EBVaGC, which may contribute to the development of gastric carcinomas. EBV has no significant effect on induction of TGF-β1 expression. Detection of RB methylation, RB expression, and TGF-β1 expression may be helpful to judge the status of tumor invasion and lymph node metastasis in gastric carcinomas.

Inactivation of COX-2, HMLH1 and CDKN2A gene by promoter methylation in gastric cancer: relationship with histological subtype, tumor location and Helicobacter pylori genotype

OBJECTIVE

We aimed to evaluate the inactivation of COX-2, HMLH1 and CDKN2A by promoter methylation and its relationship with the infection by different Helicobacter pylori strains in gastric cancer.

METHODS

DNA extracted from 76 H. pylori-positive gastric tumor samples was available for promoter methylation identification by methylation-specific PCR and H. pylori subtyping by PCR. Immunohistochemistry was used to determine COX-2, p16(INK4A) and HMLH1 expression.

RESULTS

A strong negative correlation was found between the expression of these markers and the presence of promoter methylation in their genes. Among cardia tumors, negativity of p16(INK4A) was a significant finding. On the other hand, in noncardia tumors, the histological subtypes had different gene expression patterns. In the intestinal subtype, a significant finding was HMLH1 inactivation by methylation, while in the diffuse subtype, CDKN2A inactivation by methylation was the significant finding. Tumors with methylated COX-2 and HMLH1 genes were associated with H. pylori vacA s1 (p = 0.025 and 0.047, respectively), and the nonmethylated tumors were associated with the presence of the gene flaA.

CONCLUSIONS

These data suggest that the inactivation of these genes by methylation occurs by distinct pathways according to the histological subtype and tumor location and depends on the H. pylori genotype.

Pleomorphic liposarcoma: clinical observations and molecular variables

BACKGROUND

Pleomorphic liposarcoma (PLS) is a rare high-grade sarcoma that has lipoblastic differentiation. In this study, the authors evaluated PLS natural history, patient outcomes, and commonly deregulated protein biomarkers.

METHODS

Medical records from patients (n = 155) who had PLS from 1993 to 2010 were reviewed. Univariate and multivariate analyses were conducted to identify independent prognosticators. A PLS tissue microarray (TMA) (n = 56 patient specimens) was constructed for immunohistochemical analysis of molecular markers, and p53 gene sequencing (exons 5-9) was conducted.

RESULTS

The average patient age was 57 years, and the patients presented with primary disease (n = 102), recurrent disease (n = 16), and metastatic disease (n = 37). Lower extremity was the most common disease site (40%), and the average tumor size was 11 cm. Complete follow-up data were available for 83 patients, and their median follow-up was 22.6 months. The 5-year disease-specific survival rate was 53%; and recurrent disease, unresectability, and microscopic positive margins were identified as predictors of a poor prognosis. Systemic relapse (the strongest poor prognostic determinant) developed in 35% of patients with localized PLS. Immunohistochemical analysis revealed increased expression of peroxisome proliferator-activated receptor gamma (an adipogenic marker), B-cell leukemia 2 and survivin (survival factors), vascular endothelial growth factor (an angiogenic factor), matrix metalloproteinase 2, and other biomarkers. Frequent loss of retinoblastoma protein expression and high p53 mutation rates (approximately 60%) were observed.

CONCLUSIONS

PLS is an aggressive, metastasizing sarcoma. Identifying ubiquitous molecular events underlying PLS progression is crucial for progress in patient management and outcomes.

Expression ratio of CCND1 to CDKN2A mRNA predicts RB1 status of cultured cancer cell lines and clinical tumor samples

Background

The retinoblastoma product (RB1) is frequently deregulated in various types of tumors by mutation, deletion, or inactivation through association with viral oncoproteins. The functional loss of RB1 is recognized to be one of the hallmarks that differentiate cancer cells from normal cells. Many researchers are attempting to develop anti-tumor agents that are preferentially effective against RB1-negative tumors. However, to identify patients with RB1-negative cancers, it is imperative to develop predictive biomarkers to classify RB1-positive and -negative tumors.

Results

Expression profiling of 30 cancer cell lines composed of 16 RB1-positive and 14 RB1-negative cancers was performed to find genes that are differentially expressed between the two groups, resulting in the identification of an RB1 signature with 194 genes. Among them, critical RB1 pathway components CDKN2A and CCND1 were included. We found that microarray data of the expression ratio of CCND1 and CDKN2A clearly distinguished the RB1 status of 30 cells lines. Measurement of the CCND1/CDKN2A mRNA expression ratio in additional cell lines by RT-PCR accurately predicted RB1 status (12/12 cells lines). The expression of CCND1/CDKN2A also correlated with RB1 status in xenograft tumors in vivo. Lastly, a CCND1/CDKN2A assay with clinical samples showed that uterine cervical and small cell lung cancers known to have a high prevalence of RB1-decifiency were predicted to be 100% RB1-negative, while uterine endometrial or gastric cancers were predicted to be 5-22% negative. All clinically normal tissues were 100% RB1-positive.

Conclusions

We report here that the CCND1/CDKN2A mRNA expression ratio predicts the RB1 status of cell lines in vitro and xenograft tumors and clinical tumor samples in vivo. Given the high predictive accuracy and quantitative nature of the CCND1/CDKN2A expression assay, the assay could be utilized to stratify patients for anti-tumor agents with preferential effects on either RB1-positive or -negative tumors.

Gastrin suppresses the interdependent expression of p16 and anion exchanger 1 favoring growth inhibition of gastric cancer cells

Our previous studies demonstrated that expression and interaction of p16 with anion exchanger 1 (AE1) in gastric cancer cells is correlated with progression and shorter survival of the cancer. In this article, the effects of gastrin on p16 and AE1 and its implication in prevention and treatment of gastric cancer were studied by molecular biology techniques, animal experiment and clinical analysis. The results showed that expression of p16 in human gastric body carcinoma was downregulated along with the progression of the cancer, suggesting the reverse correlations between gastrin and p16 in vivo. Further experiments indicated that gastrin suppressed the expression of p16 via the p16 promoter and thereafter resulted in the degradation of AE1 in gastric cancer cells. Silencing of AE1 or p16 significantly inhibited the proliferation of the cancer cells. Using a xenograft tumor model in nude mice, we showed that experimental systemic hypergastrinemia induced by the administration of omeprazole led to decreased expression of AE1 and p16 as well as to a marked growth inhibition of SGC7901 tumors. It is concluded that a moderate plasma gastrin level is beneficial to the growth inhibition of gastric cancer by suppressing the expression of AE1 and p16. This finding may have an important implication for the prevention and treatment of cancers arise in the gastric antrum.

Overexpression of p73 as a tissue marker for high-risk gastritis

PURPOSE

Histologic assessment of high-risk gastritis for the development of gastric cancer is not well defined. The identification of tissue markers together with the integration of histologic features will be required for this assessment.

EXPERIMENTAL DESIGN

Matched tumor/nontumor adjacent mucosa (NTAM) of 91 early gastric cancer and 148 chronic gastritis cases were evaluated for histologic characteristics (atrophy, intestinal metaplasia, chronic inflammation, polymorphonuclear infiltration, and Helicobacter pylori) by the Sydney System. Atrophy risk assessment was also evaluated by the Operative Link on Gastritis Assessment (OLGA) staging system. Eight tissue markers (BRCA1, HSP90, STAT1, FHIT, EGFR, p73, p53, p16INK4a) and EBV were also evaluated by tissue microarray/immunohistochemistry/in situ hybridization platform. Data were analyzed by contingency tables (2 x 2) using Fisher's exact two-tailed test (P < 0.001) and integrated by Significance Analysis of Microarrays (SAM) and clustering analysis.

RESULTS

Histologically, NTAM have severe intestinal metaplasia/chronic inflammation and severe atrophy assessed by Sydney and OLGA staging systems. H. pylori infection was similar in both groups, and EBV was found only in 5.5% of the tumor samples. Overexpression of p73 was higher in NTAM (50.5%) than in chronic gastritis (10.8%; P < 0.0001). Integration of histologic features and tissue markers showed that overexpression of p73, severe atrophy, and OLGA stage 4 were the most relevant features in NTAM. Clustering analysis correctly assigned NTAM and control cases (P < 0.0001).

CONCLUSIONS

Overexpression of p73 should be considered for the assessment of high-risk chronic gastritis. SAM allows the integration of histology and tissue markers for this assessment.

CDKN2A promoter methylation is related to the tumor location and histological subtype and associated with Helicobacter pylori flaA(+) strains in gastric adenocarcinomas

Promoter hypermethylation of CDKN2A (p16INK4A protein) is the main mechanism of gene inactivation. However, its association with Helicobacter pylori infection is a controversial issue. Therefore, we examined a series of gastric adenocarcinomas to assess the association between p16INK4A inactivation and H. pylori genotype (vacA, cagA, cagE, virB11 and flaA) according to the location and histological subtype of the tumors. p16INK4A expression and CDKN2A promoter methylation were found in 77 gastric adenocarcinoma samples by immunohistochemistry and methylation-specific PCR, respectively. Helicobacter pylori infection and genotype were determined by PCR. A strong negative correlation between immunostaining and CDKN2A promoter region methylation was found. In diffuse subtype tumors, the inactivation of p16INK4A by promoter methylation was unique in noncardia tumors (p=0.022). In addition, H. pylori-bearing flaA was associated with non-methylation tumors (p=0.008) and H. pylori strain bearing cagA or vacAs1m1 genes but without flaA was associated with methylated tumors (p=0.022 and 0.003, respectively). Inactivation of p16INK4A in intestinal and diffuse subtypes showed distinct carcinogenic pathways, depending on the tumor location. Moreover, the process of methylation of the CDKN2A promoter seems to depend on the H. pylori genotype. The present data suggest that there is a differential influence and relevance of H. pylori genotype in gastric cancer development.

Evaluation of cell cycle protein expression in gastric cancer: cyclin B1 expression and its prognostic implication

The cell cycle progression is regulated by interactions of specific cyclin-dependent kinases at the G1-S and G2-M checkpoints. In addition, the cell cycle dysregulation plays a major role in carcinogenesis of human cancers. To investigate the role of cell cycle regulators in the pathogenesis and progression of human gastric cancer, the expression of cyclin D1, A, B1, p16(INK4a), p21(CPI1), p27(KIP1), p53, and pRb was investigated in 482 gastric carcinomas using immunohistochemistry in terms of histologic type, tumor invasion, size, location, and metastatic behavior. The cyclin D1, A, and B1 expression (>10%) was observed in 49%, 69%, and 49% of the cases, respectively. Negative cases for p16(INK4a), p21(CPI1), and p27(KIP1) were detected in 90%, 86%, and 50.5%. There were 30% and 68% of the gastric tumors positive for p53 and pRb, respectively. Diffuse carcinomas frequently were positive for cyclin B1 and pRb, and negative for p21. A relationship between p53 expression and intestinal type carcinomas was found. In addition, the expression of cyclin B1 was associated with regional lymph node metastasis and poor prognosis. No relationship was noticed between any other cell cycle proteins expression and age, sex, tumor size, tumor location, and lymph node involvement. These findings have shown alterations in several cell cycle regulators, and it was suggested that cyclin B1 expression is closely associated with poor behavior in gastric cancer.

Genomic-wide analysis of lymphatic metastasis-associated genes in human hepatocellular carcinoma

AIM: To identify the genes related to lymph node metastasis in human hepatocellular carcinoma (HCC), 32 HCC patients with or without lymph node metastasis were investigated by high-throughput microarray comprising 886 genes.

METHODS: The samples of cancerous and non-cancerous paired tissue were taken from 32 patients with HCC who underwent hepatectomy with lymph node dissection. Total RNA was extracted from the cells obtained by means of laser microdissection (LCM) and was amplified by the T7-based amplification system. Then, the amplified samples were applied in the cDNA microarray comprising of 886 genes.

RESULTS: The results demonstrated that 25 up-regulated genes such as cell membrane receptor, intracellular signaling and cell adhesion related genes, and 48 down-regulated genes such as intracellular signaling and cell cycle regulator-related genes, were correlated with lymph node metastasis in HCC. Amongst them were included some interesting genes, such as MET, EPHA2, CCND1, MMP2, MMP13, CASP3, CDH1, and PTPN2. Expression of 16 genes (MET, CCND1, CCND2, VEGF, KRT18, RFC4, BIRC5, CDC6, MMP2, BCL2A1, CDH1, VIM, PDGFRA, PTPN2, SLC25A5 and DSP) were further confirmed by real-time quantitative reverse transcriptional polymerase chain reaction (RT-PCR).

CONCLUSION: Tumor metastasis is an important biological characteristic, which involves multiple genetic changes and cumulation. This genome-wide information contributes to an improved understanding of molecular alterations during lymph node metastasis in HCC. It may help clinicians to predict metastasis of lymph nodes and assist researchers in identifying novel therapeutic targets for metastatic HCC patients.