Reciprocal regulation of Daxx and PIK3CA promotes colorectal cancer cell growth.

Upregulation of death-domain-associated protein (Daxx) is strongly associated with diverse cancer types. Among these, the clinicopathological significance and molecular mechanisms of Daxx overexpression in colorectal cancer (CRC) remain unknown. Here, we showed that Daxx expression was increased in both clinical CRC samples and CRC cell lines. Daxx knockdown significantly reduced proliferation activity in CRC cells and tumor growth in a xenograft model. Further studies revealed that Daxx expression could be attenuated by either treatment with the PIK3CA inhibitor PIK-75 or PIK3CA depletion in CRC cells. Conversely, expression of PIK3CA constitutively active mutants could increase Daxx expression. These data suggest that PIK3CA positively regulates Daxx expression. Consistently, the expression levels of PIK3CA and Daxx were positively correlated in sporadic CRC samples. Interestingly, Daxx knockdown or overexpression yielded decreased or increased levels of PIK3CA, respectively, in CRC cells. We further demonstrated that Daxx activates the promoter activity and expression of PIK3CA. Altogether, our results identify a mechanistic pathway of Daxx overexpression in CRC and suggest a reciprocal regulation between Daxx and PIK3CA for CRC cell growth.

Enrichment of Prevotella intermedia in human colorectal cancer and its additive effects with Fusobacterium nucleatum on the malignant transformation of colorectal adenomas.

BACKGROUND: Owing to the heterogeneity of microbiota among individuals and populations, only Fusobacterium nucleatum and Bacteroides fragilis have been reported to be enriched in colorectal cancer (CRC) in multiple studies. Thus, the discovery of additional bacteria contributing to CRC development in various populations can be expected. We aimed to identify bacteria associated with the progression of colorectal adenoma to carcinoma and determine the contribution of these bacteria to malignant transformation in patients of Han Chinese origin. METHODS: Microbiota composition was determined through 16S rRNA V3-V4 amplicon sequencing of autologous adenocarcinomas, adenomatous polyps, and non-neoplastic colon tissue samples (referred to as "tri-part samples") in patients with CRC. Enriched taxa in adenocarcinoma tissues were identified through pairwise comparison. The abundance of candidate bacteria was quantified through genomic quantitative polymerase chain reaction (qPCR) in tissue samples from 116 patients. Associations of candidate bacteria with clinicopathological features and genomic and genetic alterations were evaluated through odds ratio tests. Additionally, the effects of candidate bacteria on CRC cell proliferation, migration, and invasion were evaluated through the co-culture of CRC cells with bacterial cells or with conditioned media from bacteria. RESULTS: Prevotella intermedia was overrepresented in adenocarcinomas compared with paired adenomatous polyps. Furthermore, co-abundance of P. intermedia and F. nucleatum was observed in tumor tissues. More notably, the coexistence of these two bacteria in adenocarcinomas was associated with lymph node involvement and distant metastasis. These two bacteria also exerted additive effects on the enhancement of the migration and invasion abilities of CRC cells. Finally, conditioned media from P. intermedia promoted the migration and invasion of CRC cells. CONCLUSION: This report is the first to demonstrate that P. intermedia is enriched in colorectal adenocarcinoma tissues and enhances the migration and invasion abilities of CRC cells. Moreover, P. intermedia and F. nucleatum exert additive effects on the malignant transformation of colorectal adenomas into carcinomas. These findings can be used to identify patients at a high risk of malignant transformation of colorectal adenomas or metastasis of CRC, and they can accordingly be provided optimal clinical management.

Tazarotene-induced gene 1 interacts with Polo-like kinase 2 and inhibits cell proliferation in HCT116 colorectal cancer cells.

Tazarotene-induced gene 1 (TIG1) is considered to be a tumor suppressor gene that is highly expressed in normal or well-differentiated colon tissues, while downregulation of TIG1 expression occurs in poorly differentiated colorectal cancer (CRC) tissues. However, it is still unclear how TIG1 regulates the tumorigenesis of CRC. Polo-like kinases (Plks) are believed to play an important role in regulating the cell cycle. The performance of PLK2 in CRC is negatively correlated with the differentiation status of CRC tissues. Here, we found that PLK2 can induce the growth of CRC cells and that TIG1 can prevent PLK2 from promoting the proliferation of CRC cells. We also found that the expression of PLK2 in CRC cells was associated with low levels of Fbxw7 protein and increased expression of cyclin E1. When TIG1 was coexpressed with PLK2, the changes in Fbxw7/cyclin E1 levels induced by PLK2 were reversed. In contrast, silencing TIG1 promoted the proliferation of CRC, and when PLK2 was also silenced, the proliferation of CRC cells induced by TIG1 silencing was significantly inhibited. The above research results suggest that TIG1 can regulate the tumorigenesis of CRC by regulating the activity of PLK2.

NKX6.1 hypermethylation predicts the outcome of stage II colorectal cancer patients undergoing chemotherapy.

Colorectal cancer (CRC) is a common malignancy worldwide. CRC patients in the same stage often present with dramatically different clinical scenarios. Thus, robust prognostic biomarkers are urgently needed to guide therapies and improve treatment outcomes. The NKX6.1 gene has been identified as a hypermethylation marker in cervical cancer, functioning as a metastasis suppressor by regulating epithelial-mesenchymal transition. Here, we investigated whether hypermethylation of NKX6.1 might be a prognostic biomarker for CRC. By analyzing the methylation and expression of NKX6.1 in CRC tissues and CRC cell lines. We quantitatively examined the NKX6.1 methylation levels in 151 pairs of CRC tissues by using methylation-specific polymerase chain reaction analysis and found that NKX6.1 was hypermethylated in 35 of 151 CRC tissues (23%). NKX6.1 gene expression was inversely correlated with the DNA methylation level in CRC cell lines in vitro. Then, we analyzed the association of NKX6.1 methylation with clinical characteristics of these CRC patients. Our data demonstrated that patients with NKX6.1 methylation presented poorer 5-year overall survival (P = 0.0167) and disease-free survival (P = 0.0083) than patients without NKX6.1 methylation after receiving adjuvant chemotherapy. Most importantly, these data revealed that stage II CRC patients with NKX6.1 methylation had poorer 5-year disease-free survival (P = 0.0322) than patients without NKX6.1 methylation after adjuvant chemotherapy. Our results demonstrate that methylation of NKX6.1 is a novel prognostic biomarker in CRC and that it may be used as a predictor of the response to chemotherapy.

Rectal cancer with complete clinical response after neoadjuvant chemoradiotherapy, surgery, or "watch and wait".

PURPOSE: The purpose of this study was to compare the outcomes of patients treated with chemoradiotherapy with a complete clinical response followed by either a "watch and wait" strategy or a total mesorectal excision. METHODS: This was an observational retrospective study from a single institute. Patients with locally advanced rectal cancer following chemoradiotherapy with a complete clinical response from January 1, 2007 to December 31, 2014 were included. RESULTS: The study population consisted of 18 patients who opted for a "watch and wait" policy and 26 patients who underwent radical surgery after achieving a complete clinical response. Patients had no documented treatment complications under the watch and wait policy, while 13 patients who underwent radical surgery experienced significant morbidity. There were two local recurrences in the watch and wait group; both were treated with salvage resection and had no associated mortality. In the radical surgery group, 1 patient showed an incomplete pathologic response (ypT0N1), and the remaining 25 patients showed complete pathologic responses; 1 had a distant recurrence, which was managed non-operatively, and 2 patients died of unrelated causes. The 5-year overall survival rate and median disease-free survival time were 100% and 69.78 months in the watch and wait group and 92.30% and 89.04 months in the radical surgery group. CONCLUSIONS: A watch and wait policy avoids the morbidity associated with radical surgery and preserves oncologic outcomes in our retrospective study from a single institute. It could be considered a therapeutic option in patients with locally advanced rectal cancer following chemoradiotherapy with a complete clinical response.

Phospholipase A/Acyltransferase enzyme activity of H-rev107 inhibits the H-RAS signaling pathway.

BACKGROUND: H-rev107, also called HRASLS3 or PLA2G16, is a member of the HREV107 type II tumor suppressor gene family. Previous studies showed that H-rev107 exhibits phospholipase A/acyltransferase (PLA/AT) activity and downregulates H-RAS expression. However, the mode of action and the site of inhibition of H-RAS by H-rev107 are still unknown. RESULTS: Our results indicate that H-rev107 was co-precipitated with H-RAS and downregulated the levels of activated RAS (RAS-GTP) and ELK1-mediated transactivation in epidermal growth factor-stimulated and H-RAS-cotransfected HtTA cervical cancer cells. Furthermore, an acyl-biotin exchange assay demonstrated that H-rev107 reduced H-RAS palmitoylation. H-rev107 has been shown to be a PLA/AT that is involved in phospholipid metabolism. Treating cells with the PLA/AT inhibitor arachidonyl trifluoromethyl ketone (AACOCF3) or methyl arachidonyl fluorophosphate (MAFP) alleviated H-rev107-induced downregulation of the levels of acylated H-RAS. AACOCF3 and MAFP also increased activated RAS and ELK1-mediated transactivation in H-rev107-expressing HtTA cells following their treatment with epidermal growth factor. In contrast, treating cells with the acyl-protein thioesterase inhibitor palmostatin B enhanced H-rev107-mediated downregulation of acylated H-RAS in H-rev107-expressing cells. Palmostatin B had no effect on H-rev107-induced suppression of RAS-GTP levels or ELK1-mediated transactivation. These results suggest that H-rev107 decreases H-RAS activity through its PLA/AT activity to modulate H-RAS acylation. CONCLUSIONS: We made the novel observation that H-rev107 decrease in the steady state levels of H-RAS palmitoylation through the phospholipase A/acyltransferase activity. H-rev107 is likely to suppress activation of the RAS signaling pathway by reducing the levels of palmitoylated H-RAS, which decreases the levels of GTP-bound H-RAS and also the activation of downstream molecules. Our study further suggests that the PLA/AT activity of H-rev107 may play an important role in H-rev107-mediated RAS suppression.

Tazarotene-induced Gene 1 Induces Melanoma Cell Death by Triggering Endoplasmic Reticulum Stress Response.

BACKGROUND: This study investigated the mechanism by which tazarotene-induced gene 1 (TIG1) inhibits melanoma cell growth. The main focus was to analyze downstream genes regulated by TIG1 in melanoma cells and its impact on cell growth. METHODS: The effects of TIG1 expression on cell viability and death were assessed using water-soluble tetrazolium 1 (WST-1) mitochondrial staining and lactate dehydrogenase release assays. RNA sequencing and Western blot analysis were employed to investigate the genes regulated by TIG1 in melanoma cells. Additionally, the correlation between TIG1 expression and its downstream genes was analyzed in a melanoma tissue array. RESULTS: TIG1 expression in melanoma cells was associated with decreased cell viability and increased cell death. RNA-sequencing (RNA-seq), quantitative reverse transcription PCR (reverse RT-QPCR), and immunoblots revealed that TIG1 expression induced the expression of Endoplasmic Reticulum (ER) stress response-related genes such as Homocysteine-responsive endoplasmic reticulum-resident ubiquitin-like domain member 1 (HERPUD1), Binding immunoglobulin protein (BIP), and DNA damage-inducible transcript 3 (DDIT3). Furthermore, analysis of the melanoma tissue array revealed a positive correlation between TIG1 expression and the expression of HERPUD1, BIP, and DDIT3. Additionally, attenuation of the ER stress response in melanoma cells weakened the impact of TIG1 on cell growth. CONCLUSIONS: TIG1 expression effectively hinders the growth of melanoma cells. TIG1 induces the upregulation of ER stress response-related genes, leading to an increase in caspase-3 activity and subsequent cell death. These findings suggest that the ability of retinoic acid to prevent melanoma formation may be associated with the anticancer effect of TIG1.

Involvement of the prostaglandin D2 signal pathway in retinoid-inducible gene 1 (RIG1)-mediated suppression of cell invasion in testis cancer cells.

Retinoid-inducible gene 1 (RIG1), also called tazarotene-induced gene 3, belongs to the HREV107 gene family, which contains five members in humans. RIG1 is expressed in high levels in well-differentiated tissues, but its expression is decreased in cancer tissues and cancer cell lines. We found RIG1 to be highly expressed in testicular cells. When RIG1 was expressed in NT2/D1 testicular cancer cells, neither cell death nor cell viability was affected. However, RIG1 significantly inhibited cell migration and invasion in NT2/D1 cells. We found that prostaglandin D2 synthase (PTGDS) interacted with RIG1 using yeast two-hybrid screens. Further, we found PTGDS to be co-localized with RIG1 in NT2/D1 testis cells. In RIG1-expressing cells, elevated levels of prostaglandin D2 (PGD2), cAMP, and SRY-related high-mobility group box 9 (SOX9) were observed. This indicated that RIG1 can enhance PTGDS activity. Silencing of PTGDS expression significantly decreased RIG1-mediated cAMP and PGD2 production. Furthermore, silencing of PTGDS or SOX9 alleviated RIG1-mediated suppression of migration and invasion. These results suggest that RIG1 will suppress cell migration/invasion through the PGD2 signaling pathway. In conclusion, RIG1 can interact with PTGDS to enhance its function and to further suppress NT2/D1 cell migration and invasion. Our study suggests that RIG1-PGD2 signaling might play an important role in cancer cell suppression in the testis.

H-rev107 regulates prostaglandin D2 synthase-mediated suppression of cellular invasion in testicular cancer cells.

BACKGROUND: H-rev107 is a member of the HREV107 type II tumor suppressor gene family which includes H-REV107, RIG1, and HRASLS. H-REV107 has been shown to express at high levels in differentiated tissues of post-meiotic testicular germ cells. Prostaglandin D2 (PGD2) is conjectured to induce SRY-related high-mobility group box 9 (SOX9) expression and subsequent Sertoli cell differentiation. To date, the function of H-rev107 in differentiated testicular cells has not been well defined. RESULTS: In the study, we found that H-rev107 was co-localized with prostaglandin D2 synthase (PTGDS) and enhanced the activity of PTGDS, resulting in increase of PGD2 production in testis cells. Furthermore, when H-rev107 was expressed in human NT2/D1 testicular cancer cells, cell migration and invasion were inhibited. Also, silencing of PTGDS would reduce H-rev107-mediated increase in PGD2, cAMP, and SOX9. Silencing of PTGDS or SOX9 also alleviated H-rev107-mediated suppression of cell migration and invasion. CONCLUSIONS: These results revealed that H-rev107, through PTGDS, suppressed cell migration and invasion. Our data suggest that the PGD2-cAMP-SOX9 signal pathway might play an important role in H-rev107-mediated cancer cell invasion in testes.

Predicting the progress of colon cancer by DNA methylation markers of the p16 gene in feces - Evidence from an animal model.

A new noninvasive screening tool for colorectal neoplasia detects epigenetic alterations exhibited by gastrointestinal tumor cells shed into stool. There is insufficient existing data to determine temporal associations between colorectal cancer (CRC) progression and aberrant DNA methylation. To evaluate the feasibility of using fecal DNA methylation status to determine CRC progression, we collected stool samples from 14 male SD rats aged six weeks, and administered subcutaneous injections of either 1,2-dimethylhydrazine or saline weekly. p16 DNA methylation statuses in tumorous and normal colon tissue, and from stool samples were determined using methylation-specific PCR. Additionally, p16 methylation was detected in stool DNA from 85.7% of the CRC rats. The earliest change in p16 methylation status in the DMH-treated group stool samples occurred during week nine; repeatabilities were 57.1% in week 19 (p = 0.070) and 85.7% in week 34 (p = 0.005). A temporal correlation was evidenced between progression of CRC and p16 methylation status, as evidenced by DMH-induced rat feces. Using fecal DNA methylation status to determine colorectal tissue methylation status can reveal CRC progression. Our data suggests that p16 promoter methylation is a feasible epigenetic marker for the detection and may be useful for CRC screening.

TIG1 Inhibits the mTOR Signaling Pathway in Malignant Melanoma Through the VAC14 Protein.

BACKGROUND/AIM: Currently, there are few drug options available to treat malignant melanoma. Tazarotene-inducible gene 1 (TIG1) was originally isolated from skin tissue, but its function in skin tissue has not been clarified. The aim of this study was to elucidate the effect of TIG1 and mTOR signaling pathways associated with VAC14 on melanoma. MATERIALS AND METHODS: The expression of TIG1 and VAC14 in melanoma tissue was analyzed using a melanoma tissue cDNA array. The interaction between TIG1 and VAC14 was analyzed using immunoprecipitation and immunostaining. Western blot was used to investigate the molecular targets of TIG1 and VAC14 in melanoma cells. RESULTS: TIG1 was highly expressed in normal skin tissue but was low in malignant melanoma, while VAC14 showed the opposite trend. TIG1 inhibited insulin-induced cell proliferation and insulin-activated mammalian target of rapamycin complex 1 (mTORC1)-p70 S6 kinase but did not affect the level of phospho-AKT in A2058 melanoma cells. This suggests that the main target of TIG1 regulating cell growth is phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2] rather than the PI(4,5)P2 signaling pathway. Additional TIG1 showed no additive effect on the inhibition of mTOR signaling in the absence of VAC14 expression, suggesting that TIG1 inhibited the activation of mTOR mainly by inhibiting VAC14. CONCLUSION: TIG1 may play an important role in preventing malignant melanoma through retinoic acid via VAC14.

Safety and Efficacy of Oral Nalbuphine on Postoperative Pain in Hemorrhoidectomy Patients: A Randomized, Double-blind, Placebo-controlled, Pivotal Trial.

OBJECTIVES: Severe postoperative pain requiring opioid treatment has been reported in 20% to 40% of hemorrhoidectomy patients. Compared with morphine, nalbuphine offers better hemodynamic stability, a lower risk of respiratory depression, and a lower potential for addiction. Nalbuphine was developed from the intravenous form into an oral form (PHN131) to alleviate moderate-to-severe pain. MATERIALS AND METHODS: A randomized, double-blind, placebo-controlled, multiple-dose, parallel-design trial was conducted to evaluate the safety and efficacy of PHN131 in patients undergoing hemorrhoidectomy. Eligible patients were randomly assigned to receive either PHN131 soft capsules containing nalbuphine hydrochloride 60 mg or placebo capsules. Intramuscular diclofenac was the rescue analgesic. Pain was measured by the area under the curve of mean Visual Analog Scale pain intensity scores. RESULTS: Visual Analog Scale results in patients receiving PHN131 were significantly lower than placebo group scores through 48 hours postoperatively (149.2±75.52 vs. 179.6±65.97; P =0.0301). According to Brief Pain Inventory Short-Form scores, the impact of pain on quality of life was significantly smaller for the PHN131 group than for the placebo group. Time to the first use of diclofenac postoperatively was significantly longer in the PHN131 group than in the placebo group. The cumulative dosage of diclofenac in the PHN131 group was only around half of that in the placebo group ( P <0.0001). Drug-related adverse events were mild-to-moderate and resolved by the treatment end. No drug-related severe adverse events were observed. DISCUSSION: Our findings demonstrate that PHN131 is effective and well-tolerated in the treatment of moderate-to-severe post hemorrhoidectomy pain and may provide another option for patients to control their pain.

Cytoplasmic CD133 expression is a reliable prognostic indicator of tumor regression after neoadjuvant concurrent chemoradiotherapy in patients with rectal cancer.

BACKGROUND: Despite development in therapeutic strategies, such as neoadjuvant concurrent chemoradiotherapy (CCRT), the prognosis of colorectal cancer remains relatively poor. Cancer stem cells (CSC) with several characteristics can lead to therapeutic resistance. CD133 has been identified as a putative CSC marker in colorectal cancer; however, its functional role still needs elucidation. We verified the role of CD133 with emphasis on expression location and correlated the results of CD133 with clinical outcome in colorectal cancer. METHODS: We used immunohistochemistry to investigate the expression of CD133 in samples from 157 patients with colonic adenocarcinoma and from 76 patients with rectal adenocarcinoma who received neoadjuvant CCRT. We also correlated the expression location of CD133 with the clinicopathological parameters and prognosis. RESULTS: CD133 protein was variably overexpressed in colorectal cancer tissues and was present in three locations: apical and/or endoluminal surfaces, cytoplasm, and lumen. Cytoplasmic CD133 expression level correlated significantly with tumor local recurrence (P = 0.025) and survival of patients with colorectal cancer (P = 0.002), and correlated inversely with tumor regression grading (P = 0.021) after CCRT in patients with rectal cancer. CONCLUSIONS: The expression of CD133 in the cytoplasm is closely associated with local recurrence and patient survival, and may provide a reliable prognostic indicator of tumor regression grading in patients with rectal cancer after CCRT. Cytoplasmic CD133 expression may also help identify the surviving cancer cells in areas with nearly total regression after CCRT.

Discordance between EGFR expression and clinicopathologic parameters of colorectal adenocarcinoma in Taiwan.

Dysregulation of epidermal growth factor receptor (EGFR) has been associated with colorectal cancer, but no evidence shows a relationship of EGFR expression to clinicopathological parameters in colorectal cancer in Taiwan. Immunohistochemical analysis of EGFR, Ki67, and p53 was performed in tissue microarray slides of 9 normal glandular tissues and 150 specimens including 49 well, 58 moderately, and 43 poorly differentiated colorectal adenocarcinomas. Differences in intensity of EGFR immunostaining and the percentages of Ki67 and p53 positive cells between normal and tumor specimens were evaluated using the Student t-test, one-way ANOVA, and linear regression analysis. Intensity of EGFR staining was weak and nuclear expression of Ki67 and p53 was scattered in all 9 control specimens. Expression of Ki67 and p53 but not EGFR was significantly higher in more advanced grades and TNM stages of colorectal adenocarcinoma than in normal controls. The percentages of Ki67 and p53 stained tumor cells were significantly higher in moderately (Ki67: 60.3 ± 6.5, p53: 47.6 ± 3.8) and poorly (Ki67: 61.8 ± 5.3, p53: 55.1 ± 4.1) differentiated tumor cells than in well differentiated (Ki67: 40.8 ± 4.4, p53: 39.8 ± 4.2) tumor cells. Additionally, the Ki67 and p53 staining intensity was also significantly correlated with the more advanced T, N and American Joint Committee on Cancer (AJCC) clinical stage of colorectal adenocarcinoma, suggesting their usefulness as biomarkers of colorectal adenocarcinoma progression. In conclusion, EGFR immunochemistry may not be a good method for pre-treatment evaluation of colorectal adenocarcinoma in Taiwan.

Genomic and Metabolomic Landscape of Right-Sided and Left-Sided Colorectal Cancer: Potential Preventive Biomarkers.

Colorectal cancer (CRC) is the third most common cancer worldwide. The incidence and mortality rates of CRC are significantly higher in Taiwan than in other developed countries. Genes involved in CRC tumorigenesis differ depending on whether the tumor occurs on the left or right side of the colon, and genomic analysis is a keystone in the study and treatment of CRC subtypes. However, few studies have focused on the genetic landscape of Taiwanese patients with CRC. This study comprehensively analyzed the genomes of 141 Taiwanese patients with CRC through whole-exome sequencing. Significant genomic differences related to the site of CRC development were observed. Blood metabolomic profiling and polygenic risk score analysis were performed to identify potential biomarkers for the early identification and prevention of CRC in the Taiwanese population. Our findings provide vital clues for establishing population-specific treatments and health policies for CRC prevention in Taiwan.

G protein-coupled receptor kinase 5 mediates Tazarotene-induced gene 1-induced growth suppression of human colon cancer cells.

BACKGROUND: Tazarotene-induced gene 1 (TIG1) is a retinoid-inducible type II tumour suppressor gene. The B isoform of TIG1 (TIG1B) inhibits growth and invasion of cancer cells. Expression of TIG1B is frequently downregulated in various cancer tissues; however, the expression and activities of the TIG1A isoform are yet to be reported. Therefore, this study investigated the effects of the TIG1A and TIG1B isoforms on cell growth and gene expression profiles using colon cancer cells. METHODS: TIG1A and TIG1B stable clones derived from HCT116 and SW620 colon cancer cells were established using the GeneSwitch system; TIG1 isoform expression was induced by mifepristone treatment. Cell growth was assessed using the WST-1 cell proliferation and colony formation assays. RNA interference was used to examine the TIG1 mediating changes in cell growth. Gene expression profiles were determined using microarray and validated using real-time polymerase chain reaction, and Western blot analyses. RESULTS: Both TIG1 isoforms were expressed at high levels in normal prostate and colon tissues and were downregulated in colon cancer cell lines. Both TIG1 isoforms significantly inhibited the growth of transiently transfected HCT116 cells and stably expressing TIG1A and TIG1B HCT116 and SW620 cells. Expression of 129 and 55 genes was altered upon induction of TIG1A and TIG1B expression, respectively, in stably expressing HCT116 cells. Of the genes analysed, 23 and 6 genes were upregulated and downregulated, respectively, in both TIG1A and TIG1B expressing cells. Upregulation of the G-protein-coupled receptor kinase 5 (GRK5) was confirmed using real-time polymerase chain reaction and Western blot analyses in both TIG1 stable cell lines. Silencing of TIG1A or GRK5 expression significantly decreased TIG1A-mediated cell growth suppression. CONCLUSIONS: Expression of both TIG1 isoforms was observed in normal prostate and colon tissues and was downregulated in colon cancer cell lines. Both TIG1 isoforms suppressed cell growth and stimulated GRK5 expression in HCT116 and SW620 cells. Knockdown of GRK5 expression alleviated TIG1A-induced growth suppression of HCT116 cells, suggesting that GRK5 mediates cell growth suppression by TIG1A. Thus, TIG1 may participate in the downregulation of G-protein coupled signaling by upregulating GRK5 expression.

Tazarotene-induced gene 1 inhibits prostaglandin E2-stimulated HCT116 colon cancer cell growth.

BACKGROUND: The tazarotene-induced gene 1 (TIG1) is a putative tumor suppressor gene. We have recently demonstrated both TIG1A and TIG1B isoforms inhibited cell growth and induced the expression of G protein-coupled receptor kinase 5 (GRK5) in colon cancer cells. Because elevated prostaglandin E2 (PGE2) signaling plays a significant role in colorectal carcinogenesis, the objective of this study was to explore the effect of TIG1 on PGE2-induced cellular proliferation and signaling in colon cancer cells. METHODS: HCT116 cells as well as TIG1A and TIG1B stable cells established from HCT116 colon cancer cells using the GeneSwitch system were used. TIG1 isoform expression was induced by mifepristone treatment in stable cells. Cell growth was determined using the WST-1 cell proliferation assay. Activation of ß-catenin/TCF and cyclic adenosine monophosphate (cAMP)/CREB signaling pathways were determined using luciferase reporter assays. Expression and subcellular distribution of ß-catenin were analyzed using Western blot and confocal microscope. Levels of cAMP were measured using an enzyme immunoassay. RNA interference was used to examine the effects of TIG1- and GRK5-mediated changes. RESULTS: PGE2-stimulated cell growth was reduced in inducible TIG1A- and TIG1B-stable HCT116 cells. GRK5 expression was upregulated by both TIG1A and TIG1B isoforms, and its expression suppressed PGE2-stimulated HCT116 cell growth. GRK5, TIG1A, and TIG1B expression significantly inhibited PGE2-stimulated ß-catenin/TCF and cAMP signaling pathway reporters and cAMP. Also, PGE2-stimulated nuclear localization of ß-catenin was inhibited by expression of TIG1A and TIG1B, which was ameliorated by both TIG1 and GRK5 siRNAs. CONCLUSIONS: TIG1 suppressed PGE2-stimulated Wnt and cAMP signaling pathways in colon cancer cells through GRK5.

Iatrogenic colonic perforation by colonoscopy: a fatal complication for patients with a high anesthetic risk.

PURPOSE: Colonoscopy is currently a standard and widespread technique used in screening for colorectal cancer. Iatrogenic colonic perforation during colonoscopy is an unfortunate complication that can induce significant morbidity and even death. Here, we reviewed the clinical results of iatrogenic colonoscopic perforation in our hospital. METHODS: This was a retrospective review of 35,186 colonoscopies performed in the Tri-Service General Hospital, Taipei, Taiwan from January 1998 to December 2007. Patient demographic data, indications, comorbidities, operative history, perforation site, time of diagnosis, management, complications, hospital stay, and outcomes were recorded. RESULTS: In this 10-year period, 23 cases of iatrogenic colonic perforation were recorded (0.065%) affecting 11 men and 12 women. The mean age was 71.2 years. There were 13 patients in American Society of Anesthesiology (ASA) classifications 1 or 2 (low anesthetic risk, group A), and ten patients in ASA classes 3 or 4 (high anesthetic risk, group B). The mean hospital stay was 12 days in group A versus 23.5 days in group B (P = 0.002). Moreover, four patients in group B died (17%; P = 0.024). CONCLUSION: Colonoscopy-related perforation can progress to peritonitis and sepsis, resulting in serious morbidity or death. High-anesthetic risk patients with colonic perforation have a longer hospital stay and a poor prognosis. Hence, patients need to be informed of the complications of colonoscopy, and clinicians must be cautioned about the potential problems for patients with a high-anesthetic risk when performing the procedure.

Necrotizing fasciitis due to acute perforated appendicitis: case report.

Acute appendicitis is one of the most common surgical emergencies. Accurate diagnosis is often hindered due to various presentations that differ from the typical signs of appendicitis, especially the position of the appendix. A delay in treatment increases the likelihood of complications such as perforation, which is associated with an increase in morbidity and mortality rates. We herein present the case of a 76-year-old woman presenting with necrotizing fasciitis of the abdominal wall and right flank regions due to a perforated appendix. Such complication is extremely rare but life-threatening. It may be confused with cellulitis, causing a delay in aggressive treatment. This case represents an unusual complication of a common disease. Also, acute appendicitis or intra-abdominal pathologies should be taken into consideration in determining the cause of necrotizing fasciitis presenting over abdominal, flank, or perineal regions.