Intrahepatic Cholangiocarcinoma Cell Growth Research Articles

Overexpression of proteasome 26S subunit non-ATPase 6 protein and its clinicopathological significance in intrahepatic cholangiocarcinoma

BACKGROUND Currently, intrahepatic cholangiocarcinoma (ICC) poses a continuing, significant health challenge, but the relationship has yet to be established between ICC and the proteasome 26S subunit non-ATPase 6 (PSMD6). AIM To investigate the protein expression and clinicopathological significance of PSMD6 in ICC. METHODS The potential impact of the PSMD6 gene on the growth of ICC cell lines was analyzed using clustered regularly interspaced short palindromic repeat knockout screening technology. Forty-two paired specimens of ICC and adjacent non-cancerous tissues were collected. PSMD6 protein expression was determined by immunohistochemistry. Receiver operating characteristic curve analysis was performed to validate PSMD6 expression level, and its association with ICC patients’ various clinicopathological characteristics was investigated. RESULTS The PSMD6 gene was found to be essential for the growth of ICC cell lines. PSMD6 protein was significantly overexpressed in ICC tissues (P < 0.001), but showed no significant association with patient age, gender, pathological grade, or tumor-node-metastasis stage (P > 0.05). CONCLUSION PSMD6 can promote the growth of ICC cells, thus playing a pro-oncogenic role.

DCLK1 Expression and its Functional Significance in Intrahepatic Cholangiocarcinoma and Bil-IN Stage.

Although several studies in some neoplasms have reported correlation between the expression levels of Doublecortin-like kinase1(DCLK1) and carcinogenesis, its role in cholangiocarcinoma remains unknown. DCLK1 expression in normal epithelium (NE), biliary intraepithelial neoplasia (BilIN)1∼3, and intrahepatic cholangiocarcinoma (ICC) were investigated immuno-histochemically. The molecular effects of DCLK1 were investigated by gene silencing using RNAi [DCLK1-tagrgeting (siDCLK1)]. The human ICC cell lines HuCCT1 and HuH28 were transfected with these siRNAs, and used for assays in the presence or absence of DCLK1 inhibitors. The positive ratio of DCLK1 expression in ICC was higher than that in NE, and equally distributed among BilIN1∼3 (NE: BilIN1: BilIN2: BilIN3: ICC=62%: 91%: 97%: 100%: 95%, p<0.05). In the wound healing assay, the migration of the siDCLK1-treated cells was significantly inhibited compared to the NT-treated cells (p<0.05). In the cell invasion assay, the invasion of the siDCLK1-treated cells was significantly inhibited compared to the NT-treated cells (p<0.05). In the presence of the DCLK1 inhibitor, cell proliferative capacity at 24 hours was decreased in a concentration-dependent manner. DCLK1 was highly expressed in the early stage of ICC carcinogenesis. Human ICC cell growth was suppressed in vitro by siRNA silencing of DCLK1 or after treatment with the DCLK1 inhibitor, indicating DCLK1 may be molecular target for ICC therapy.

METTL5-mediated 18S rRNA m6A modification promotes oncogenic mRNA translation and intrahepatic cholangiocarcinoma progression

Intrahepatic cholangiocarcinoma (ICC) is a deadly cancer with rapid tumor progression. While hyperactive mRNA translation caused by mis-regulated mRNA or tRNA modifications promotes ICC development, the role of rRNA modifications remains elusive. Here, we found that 18S rRNA m6A modification and its methyltransferase METTL5 were aberrantly upregulated in ICC and associated with poorer survival (log rank test, p<0.05). We further revealed the critical role of METTL5-mediated 18S rRNA m6A modification in regulation of ICC cell growth and metastasis using loss- and gain-of function assays invitro and invivo. The oncogenic function of METTL5 is corroborated using liver-specific knockout and overexpression ICC mouse models. Mechanistically, METTL5 depletion impairs 18S rRNA m6A modification that hampers ribosome synthesis and inhibits translation of G-quadruplex-containing mRNAs that are enriched in the transforming growth factor (TGF)-β pathway. Our study uncovers the important role of METTL5-mediated 18S rRNA m6A modification in ICC and unravels the mechanism of rRNA m6A modification-mediated oncogenic mRNA translation control.

Circ_0000284 facilitates the growth, metastasis and glycolysis of intrahepatic cholangiocarcinoma through miR-152-3p-mediated PDK1 expression.

Circular RNAs (circRNAs) are key molecules in the regulation of intrahepatic cholangiocarcinoma (ICC) progression. The purpose of this study was to analyze the function and underlying molecular mechanism of circ_0000284 in ICC. Quantitative real-time PCR was used to analyze the circ_0000284, microRNA (miR)-152-3p and pyruvate dehydrogenase kinase 1 (PDK1) expression. Cell proliferation, apoptosis, invasion and migration were executed by cell counting kit 8 assay, EdU assay, flow cytometry, transwell assay and wound healing assay, respectively. All protein expression levels were examined using western blot analysis. Cell glycolysis was analyzed by detecting glucose consumption, lactate production and ATP/ADP ratios. Target relationship was estimated by dual-luciferase reporter assay. The effect of circ_0000284 on ICC tumor growth in vivo was evaluated by constructing xenograft mice model. We detected high expression of circ_0000284 in ICC tumor tissues and cells. Downregulated circ_0000284 inhibited ICC cell proliferation, invasion, migration, glycolysis, and accelerated apoptosis. MiR-152-3p was sponged by circ_0000284, and its inhibitor revoked the effect of circ_0000284 knockdown on ICC cell progression. PDK1 was a target of miR-152-3p, and its expression was suppressed by circ_0000284 knockdown. PDK1 overexpression reversed the inhibition effect of miR-152-3p on ICC cell growth, metastasis and glycolysis. In animal experiments, circ_0000284 downregulation also inhibited ICC tumor growth. Circ_0000284 promoted the growth, metastasis and glycolysis of ICC by miR-152-3p/PDK1 pathway, showing that circ_0000284 was a potential therapeutic target for ICC.

Suppression of intrahepatic cholangiocarcinoma cell growth by SKI via upregulation of the CDK inhibitor p21.

Cholangiocarcinoma (CC) has a poor prognosis and different driver genes depending on the site of onset. Intrahepatic CC is the second-most common liver cancer after hepatocellular carcinoma, and novel therapeutic targets are urgently needed. The present study was conducted to identify novel therapeutic targets by exploring differentially regulated genes in human CC. MicroRNA (miRNA) and mRNA microarrays were performed using tissue and serum samples obtained from 24 surgically resected hepatobiliary tumor cases, including 10 CC cases. We conducted principal component analysis to identify differentially expressed miRNA, leading to the identification of miRNA-3648 as a differentially expressed miRNA. We used an in silico screening approach to identify its target mRNA, the tumor suppressor Sloan Kettering Institute (SKI). SKI protein expression was decreased in human CC cells overexpressing miRNA-3648, endogenous SKI protein expression was decreased in human CC tumor tissues, and endogenous SKI mRNA expression was suppressed in human CC cells characterized by rapid growth. SKI-overexpressing OZ cells (human intrahepatic CC cells) showed upregulation of cyclin-dependent kinase inhibitor p21 mRNA and protein expression and suppressed cell proliferation. Nuclear expression of CDT1 (chromatin licensing and DNA replication factor 1), which is required for the G1/S transition, was suppressed in SKI-overexpressing OZ cells. SKI knockdown resulted in the opposite effects. Transgenic p21-luciferase was activated in SKI-overexpressing OZ cells. These data indicate SKI involvement in p21 transcription and that SKI-p21 signaling causes cell cycle arrest in G1, suppressing intrahepatic CC cell growth. Therefore, SKI may be a potential therapeutic target for intrahepatic CC.

The role of Tripartite motif containing 59 (TRIM59) in the proliferation and prognosis of intrahepatic cholangiocarcinoma

Tripartite motif containing 59 (TRIM59) is a crucial gene that is involved in the process of various types of cancer，including breast cancer, lung cancer, colorectal cancer,and so on. Its abnormal expression can affect tumor cell proliferation, metastasis, or apoptosis. In liver cancer, the incidence of intrahepatic cholangiocarcinoma (ICC) is increasing. However, However, it has not been clearly reported on TRIM59 affects the progress of intrahepatic cholangiocarcinoma cells.Firstly, we review the expression of TRIM59 in different cancers and the corresponding normal tissues，and the results preliminarily showed that TRIM59 may be abnormally expressed in many cancers. The author focuses on whether TRIM59 plays a crucial biological role in intrahepatic cholangiocarcinoma. Therefore, we have confirmed through online websites that TRIM59 is highly expressed in intrahepatic cholangiocarcinoma tissues. Furthermore we further found that TRIM59 can be used as an effective prognostic marker for the prognostic guidance of patient survival time. Next, we explore whether the expression level of TRIM59 in intrahepatic cholangiocarcinoma is related to proliferation through the CCK-8 and EDU assay in two ICC cell lines. To further explore how TRIM59 affected the molecular mechanism involved in intrahepatic cholangiocarcinoma cell growth, we found that STAT3 promotes TRIM59 transcription and TRIM59 can affect tumor progression by regulating the PI3K/AKT signaling pathway through luciferase reporter assay and Western blot experiments. In summary, we first found that TRIM59 has great research value in ICC through bioinformatic analysis, then its expression level is closely related to the prognosis through the analysis of clinicopathological indicators of patients with ICC, and the biological mechanism of TRIM59 in ICC provides precise research or therapeutic targets for future cancer treatment. The findings improve our understanding of the potential of TRIM59 in biological functions in ICC and may hold promise as markers for the diagnosis,treatment, and prognosis of ICC. Data availabilityThe raw data of this study are derived from the TCGA database, which are publicly available databases.

Hsa_circ_0019054 up-regulates HIF1A through sequestering miR-340-5p to promote the tumorigenesis of intrahepatic cholangiocarcinoma.

Circular RNAs (circRNAs) have been uncovered to play an important regulatory function in the tumorigenesis of intrahepatic cholangiocarcinoma (ICC). Hsa_circ_0,019,054 was found to be increased in ICC. Here, we aimed to explore the action and mechanism of hsa_circ_0,019,054 in ICC carcinogenesis. Quantitative real-time PCR (qRT-PCR) and western blotting were used to detect the levels of genes and proteins. The functional experiments were performed using in vitro 5-ethynyl-2'-deoxyuridine (EdU) assay, cell counting Kit-8 (CCK-8) assay, flow cytometry, and in vivo murine xenograft model. The glycolysis was analyzed by detecting glucose uptake and lactate level. The binding between miR-340-5p and hsa_circ_0,019,054 or HIF1A (Hypoxia-inducible factor 1-alpha) was validated using pull-down, dual-luciferase reporter and RNA immunoprecipitation assays. Hsa_circ_0,019,054 expression was higher in ICC tissues and cells. Functionally, hsa_circ_0,019,054 silencing could suppress ICC cell proliferation and glycolysis active, as well as induce apoptosis. Mechanistically, hsa_circ_0,019,054 was demonstrated to act as a sponge for miR-340-5p, which directly targeted HIF1A. Hsa_circ_0,019,054/miR-340-5p/HIF1A formed a feedback loop. HIF1A was up-regulated, while miR-340-5p was decreased in ICC tissues and cells. MiR-340-5p re-expression attenuated ICC cell growth. Besides that, rescue experiments suggested that HIF1A overexpression or miR-340-5p knockdown reversed the anti-proliferation and glycolysis arrest effects mediated by hsa_circ_0,019,054 silencing. Importantly, hsa_circ_0,019,054 silencing also impeded the growth of ICC in nude mice. Hsa_circ_0,019,054 deficiency could attenuate the proliferation and glycolysis of ICC cells via miR-340-5p/HIF1A axis.

LHPP suppresses tumorigenesis of intrahepatic cholangiocarcinoma by inhibiting the TGFβ/smad signaling pathway.

Phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP), a histidine phosphatase, plays an important role in tumor progression and metastasis as a tumor suppressor. Here, we investigate the effect of LHPP in intrahepatic cholangiocarcinoma (ICC). We discovered that LHPP was downregulated in tumor tissues and low levels of LHPP predicted poor survival. LHPP inhibited ICC cell growth, cell invasion and epithelial-mesenchymal transition (EMT) in vitro and in vivo. Mechanically, LHPP deactivated transforming growth factor‑beta (TGFβ) signaling pathway, and low level LHPP upregulated the expression of TGFβ and phosphorylation of smad2/3. Moreover, inhibition of this pathway reversed the biofunction of LHPP. In summary, these findings demonstrated that LHPP suppressed ICC through inhibiting the activation of TGFβ/smad signaling. Our results indicated that LHPP is a potential therapeutic target in ICC.

Proteomics analysis identified TPI1 as a novel biomarker for predicting recurrence of intrahepatic cholangiocarcinoma.

Intrahepatic cholangiocarcinoma (ICC) is the second most common tumor in primary liver cancer, but the prognostic factors associated with long-term outcomes after surgical resection remain poorly defined. This study aimed to develop a novel prognostic classifier for patients with ICC after surgery. Using a proteomics approach, we screened tumor markers that up-regulated in ICC tissues, and narrowed down by bioinformatics analysis, western blot and immunohistochemistry. Prognostic markers were identified using Cox regression analyses in primary training cohort and the predictive models for time to recurrence (TTR) were established. The predictive accuracy of predictive model was validated in external validation cohort and prospective validation cohort. MTT assay, clonal formation assay and trans-well assays were used to verify the effect on the proliferation and migration in ICC cell line. Triosephosphate isomerise (TPI1) was significantly up-regulated in ICC tissues and Kaplan-Meier analysis reveals that higher TPI1 expression was strongly correlated with higher recurrence rate of ICC patients. In the primary training cohort, mean TTR was significantly longer (p < 0.0001) than in the low-risk group (26.9months for TTR, 95% CI 22.4-31.5) than in the high-risk group (14.5months for TTR, 95% CI 10.6-18.4). Similar results were observed in two validation cohorts. In addition, a nomogram to predict recurrence was developed. Moreover, Knockdown of TPI1 by shRNA inhibited ICC cell growth, colony information, migration, invasion in vitro. Current prognostic models were accurate in predicting recurrence for ICC patients after surgical resection.

Combined CDK4/6 and Pan-mTOR Inhibition Is Synergistic Against Intrahepatic Cholangiocarcinoma.

Intrahepatic cholangiocarcinoma (ICC) is an aggressive cancer type, lacking effective therapies and associated with a dismal prognosis. Palbociclib is a selective CDK4/6 inhibitor, which has been shown to suppress cell proliferation in many experimental cancer models. Recently, we demonstrated that pan-mTOR inhibitors, such as MLN0128, effectively induce apoptosis, although have limited efficacy in restraining proliferation of ICC cells. Here, we tested the hypothesis that palbociclib, due to its antproliferative properties in many cancer types, might synergize with MLN0128 to impair ICC growth. Human ICC cell lines and the AKT/YapS127A ICC mouse model were used to test the therapeutic efficacy of palbociclib and MLN0128, either alone or in combination. Administration of palbociclib suppressed in vitro ICC cell growth by inhibiting cell-cycle progression. Concomitant administration of palbociclib and MLN0128 led to a pronounced, synergistic growth constraint of ICC cell lines. Furthermore, while treatment with palbociclib or MLN0128 alone resulted in tumor growth reduction in AKT/YapS127A mice, a remarkable tumor regression was achieved when the two drugs were administered simultaneously. Mechanistically, palbociclib was found to potentiate MLN0128 mTOR inhibition activity, whereas MLN0128 prevented the upregulation of cyclin D1 induced by palbociclib treatment. Our study indicates the synergistic activity of palbociclib and MLN0128 in inhibiting ICC cell proliferation. Thus, combination of CDK4/6 and mTOR inhibitors might represent a novel, promising, and effective therapeutic approach against human ICC.See related commentary by Malumbres, p. 6.

Blocking of the EGFR-STAT3 signaling pathway through afatinib treatment inhibited the intrahepatic cholangiocarcinoma.

Epidermal growth factor receptor (EGFR) and downstream signal transducer and activator of transcription 3 (STAT3) signaling have been extensively implicated in various human neoplasms. Recently, a novel EGFR inhibitor, known as afatinib, has exhibited broad antitumor activities in a variety of tumors. Therefore, the present study attempted to investigate the impact of this agent on intrahepatic cholangiocarcinoma (ICC). Initially, immunohistochemical assays were performed on 15 human ICC specimens and their adjacent tissues in order to assess the protein levels of phosphorylated EGFR (pEGFR) and pSTAT3. Subsequently, the human ICC cell lines JCK and OZ were exposed to different doses of afatinib, and then cell viability and apoptosis were determined by MTT assay and flow cytometry, respectively. Furthermore, immunoblotting was applied to detect any variations in the phosphorylated protein levels of EGFR and STAT3 in afatinib-treated ICC cells. The results of the current study demonstrated that ICC specimens had evidently increased pEGFR and pSTAT3 protein levels as compared with the adjacent noncancerous tissues. Further in vitro experiments indicated that afatinib evidently blocked ICC cell growth and induced cell apoptosis. At the protein level, pEGFR and pSTAT3 were evidently attenuated by afatinib-administration. In conclusion, the present study clearly determined that afatinib exerts an antitumor effect on ICC cells by silencing the EGFR-STAT3 signaling pathway. This novel agent deserves further investigation as a potential therapeutic strategy for ICC.

Andrographis paniculata extracts and major constituent diterpenoids inhibit growth of intrahepatic cholangiocarcinoma cells by inducing cell cycle arrest and apoptosis.

Andrographis paniculata is an important herbal medicine widely used in several Asian countries for the treatment of various diseases due to its broad range of pharmacological activities. The present study reports that A.paniculata extracts potently inhibit the growth of liver (HepG2 and SK-Hep1) and bile duct (HuCCA-1 and RMCCA-1) cancer cells. A.paniculata extracts with different contents of major diterpenoids, including andrographolide, 14-deoxy-11,12-didehydroandrographolide, neoandrographolide, and 14-deoxyandrographolide, exhibited a different potency of growth inhibition. The ethanolic extract of A.paniculata at the first true leaf stage, which contained a high amount of 14-deoxyandrographolide but a low amount of andrographolide, showed a cytotoxic effect to cancer cells about 4 times higher than the water extract of A. paniculata at the mature leaf stage, which contained a high amount of andrographolide but a low amount of 14-deoxyandrographolide. Andrographolide, not 14-deoxy-11,12-didehydroandrographolide, neoandrographolide, or 14-deoxyandrographolide, possessed potent cytotoxic activity against the growth of liver and bile duct cancer cells. The cytotoxic effect of the water extract of A.paniculata at the mature leaf stage could be explained by the present amount of andrographolide, while the cytotoxic effect of the ethanolic extract of A.paniculata at the first true leaf stage could not. HuCCA-1 cells showed more sensitivity to A. paniculata extracts and andrographolide than RMCCA-1 cells. Furthermore, the ethanolic extract of A.paniculata at the first true leaf stage increased cell cycle arrest at the G0/G1 and G2/M phases, and induced apoptosis in both HuCCA-1 and RMCCA-1 cells. The expressions of cyclin-D1, Bcl-2, and the inactive proenzyme form of caspase-3 were reduced by the ethanolic extract of A.paniculata in the first true leaf stage treatment, while a proapoptotic protein Bax was increased. The cleavage of poly (ADP-ribose) polymerase was also found in the ethanolic extract of A. paniculata in the first true leaf stage treatment. This study suggests that A.paniculata could be a promising herbal plant for the alternative treatment of intrahepatic cholangiocarcinoma.

Tumor-derived trypsin enhances proliferation of intrahepatic cholangiocarcinoma cells by activating protease-activated receptor-2

In primary malignant liver tumors, trypsinogen-immunoreactivity was present in 70% of intrahepatic cholangiocarcinoma (ICC) specimens, but absent in hepatocellular carcinoma (HCC) specimens. We suggest the secretion of trypsinogen to be a key difference in biological behavior between ICC and HCC cells. The purpose of this study was to investigate the secretion of tumor-derived trypsin and the expression of its specific receptor, protease-activated receptor-2 (PAR-2), in ICC using cell lines and surgical specimens. The expression of trypsinogen-1 mRNA was observed in three of four ICC cell lines, but none of three HCC cell lines. Western blot analysis detected trypsinogen-1 in serum-free conditioned medium from one of the ICC cell lines positive for the mRNA. Gelatin zymography revealed a gelatinolytic activity for trypsin, the activated form of trypsinogen, in the same conditioned medium. PAR-2 mRNA and protein were observed in ICC cell lines. The proliferative activity of ICC cells was increased by concentrations of trypsin as low as 10 nM, and peaked at 100 nM. The effect of trypsin was suppressed by a serine protease inhibitor, gabexate mesilate. PAR-2 expression was detected in 64% of ICC surgical specimens immunohistochemically. In addition, stroma fibroblasts expressed PAR-2 in 52% of ICC specimens. These results suggest that trypsinogen-1 contributes to the growth of ICC cells and also tumor-associated fibroblasts.

Hepatic Stellate Cells May Relate to Progression of Intrahepatic Cholangiocarcinoma

Although cumulative evidence supports the fact that stromal myofibroblasts promote tumor progression, the influence of myofibroblasts on intrahepatic cholangiocarcinoma (ICC) is unclear. We hypothesized that hepatic stellate (HS) cells can differentiate into myofibroblasts in ICC stroma and that they promote cancer progression. This study aims to: (1) assess the influence of myofibroblasts on the prognosis of ICC, (2) identify HS cells in ICC stroma, and (3) investigate the interaction between HS cells (LI90 and LX-2) and ICC cells (HuCCT-1 and MEC) in vitro. The association between alpha-smooth muscle actin (alpha-SMA) expression and the prognoses of 46 ICC patients after hepatic resection was evaluated by immunohistochemical analysis. The HS cells in myofibroblasts of ICC were identified (double immunostaining) using antibodies for alpha-SMA, glial fibrillary acidic protein (GFAP), and desmin. The influence of HS cells on the invasion and growth of ICC cells was examined in vitro using a coculture system. Patients with high alpha-SMA expression exhibited the worse outcomes. Multivariate analyses revealed that high alpha-SMA expression (P = 0.0045) and positivity for lymph-node metastasis were independent prognostic factors. Because desmin- or GFAP-positive cells coexpressing alpha-SMA were observed in the ICC samples, they were considered to be derived from the HS cells. On coculturing with HS cells, a remarkable increase was observed in the invasion and growth of the two ICC cell lines. Stromal myofibroblasts may relate to the poor prognoses in ICC patients. HS cells appear to be involved in the progression of ICC.

Enhanced Expression of RAD51 Associating Protein-1 Is Involved in the Growth of Intrahepatic Cholangiocarcinoma Cells

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary cancer in the liver, and its incidence is increasing in developed countries. To discover novel molecular targets for the diagnosis and treatment of ICCs, we earlier analyzed expression profiles of 25 ICCs using a cDNA microarray containing 27,648 genes. In this study, we focused on the RAD51 associating protein-1 (RAD51AP1) gene because its expression was frequently elevated in our microarray data. Quantitative PCR confirmed that RAD51AP1 expression was elevated in the great majority of the ICCs examined. Immunohistochemical analysis with anti-RAD51AP1 antibody further corroborated its accumulation in 14 of 23 ICC tissues (61%). Notably, suppression of RAD51AP1 by short interfering RNA resulted in growth suppression of cholangiocarcinoma cells, suggesting its involvement in the development and/or progression of ICC. Because RAD51AP1 interacts with RAD51, a molecule involved in DNA repair, we investigated whether RAD51AP1 is implicated in DNA strand breaks using gamma-irradiation. As a result, gamma-irradiation augmented RAD51AP1 protein expression and brought a focus formation in the nuclei, where accumulated RAD51AP1 colocalized with phosphorylated histone 2AX (gamma-H2AX) and RAD51. These data suggest that RAD51AP1 may play a role in cell proliferation as well as DNA repair. Our findings may contribute to the better understanding of cholangiocarcinogenesis and open a new avenue to the development of novel therapeutic and/or diagnostic approach to this type of tumor.

Effect of transforming growth factor-β1 on human intrahepatic cholangiocarcinoma cell growth

To elucidate the biological effects of transforming growth factor-beta1 (TGF-beta1) on intrahepatic cholan-giocarcinoma (ICC). We investigated the effects of TGF-beta1 on human ICC cell lines (HuCCT1, MEC, and HuH-28) by monitoring the influence of TGF-beta1 on tumor growth and interleukin-6 (IL-6) expression in ICC cells. All three human ICC cell lines produced TGF-beta1 and demonstrated accelerated growth in the presence of TGF-beta1 with no apoptotic effect. Studies on HuCCT1 revealed a TGF-beta1-induced stimulation of the expression of TGF-beta1, as well as a decrease in TGF-beta1 mRNA expression induced by neutralizing anti-TGF-beta1 antibody. These results indicate that TGF-beta1 stimulates the production and function of TGF-beta1 in an autocrine fashion. Further, IL-6 secretion was observed in all three cell lines and exhibited an inhibitory response to neutralizing anti-TGF-beta1 antibody. Experiments using HuCCT1 revealed a TGF-beta1-induced acceleration of IL-6 protein expression and mRNA levels. These findings demonstrate a functional interaction between TGF-beta1 and IL-6. All three cell lines proliferated in the presence of IL-6. In contrast, TGF-beta1 induced no growth effect in HuCCT1 in the presence of small interfering RNA against a specific cell surface receptor of IL-6 and signal transducer and activator of transcription-3. ICC cells produce TGF-beta1 and confer a TGF-beta1-induced growth effect in an autocrine fashion. TGF-beta1 activates IL-6 production, and the functional interaction between TGF-beta1 and IL-6 contributes to ICC cell growth by TGF-beta1.