MAFIP is a tumor suppressor in cervical cancer that inhibits activation of the nuclear factor-kappa B pathway

Cervical cancer is the second most common cancer in women. Inactivation of tumor suppressor genes underlies the transformation and progression of cervical cancer. Previously, we reported MAFIP can inhibit the growth of human cervical cancer HeLa cells. In this study, MAFIP was found to be downregulated in cervical intraepithelial neoplasia tissues. Induced expression of MAFIP in HeLa cells strongly inhibited tumor formation in nude mice, confirming its tumor suppressor activity in vivo. Overexpression of MAFIP inhibited activation of the NF-κB pathway, a commonly active pathway in cancer cells, by preventing the phosphorylation of IKK and IκBα, degradation of IκBα and the nuclear localization of p65. Induction of c-myc, an oncogene controlled by NF-κB, was severely impaired in the cells overexpressing MAFIP. In contrast, knockdown of MAFIP by siRNA activated the NF-κB pathway and promoted cell proliferation. These data suggest MAFIP functions as a tumor suppressor in cervical cancer in part by inhibiting activation of the NF-κB pathway.     

Lipopolysaccharide increases cyclo-oxygenase-2 expression in a colon carcinoma cell line through nuclear factor-kappa B activation

Both nonneoplastic colon epithelium and colon carcinoma cells in situ are continuously exposed to lipopolysaccharide (LPS). Few reports have addressed possible direct effects of LPS in promotion of colon carcinoma and underlying mechanisms. We found evidence that LPS directly stimulated growth of the human colon carcinoma cell line CE-1 through an increase in the production of prostaglandin E2 (PGE2) as a result of cyclo-oxygenase-2 (COX-2) expression. LPS induced significant increases in PGE2 production in CE-1 cells, which were found to express a high-affinity LPS receptor, CD14. Positive correlations were found between PGE2 production and activation of nuclear factor (NF)-kappa B as well as expression of both COX-2 mRNA and protein in LPS-stimulated CE-1 cells. When CE-1 cells were exposed to exogenous PGE2, DNA synthesis increased. These results indicate that LPS may stimulate DNA synthesis in certain colon carcinoma cells as a result of PGE2 production involving increased COX-2 expression that might result in turn from activation of NF-kappa B by LPS. Further investigation of the pathways mediating LPS-induced stimulation of colon carcinoma cells may provide insights into LPS effects in in vivo tumor biology.     

Novel proteasome inhibitor PS-341 inhibits activation of nuclear factor-kappa B, cell survival, tumor growth, and angiogenesis in squamous cell carcinoma.

We have shown that activation of nuclear factor-kappa B (NF-kappa B) promotes cell survival and expression of cytokines such as growth-regulated oncogene-alpha, which can modulate angiogenesis, growth, and metastasis of squamous cell carcinoma (SCC). Activation of NF-kappa B and cytoprotective genes in cancer may result from signal-induced phosphorylation and proteasome-dependent degradation of inhibitor-kappa B. In this study, we examined the effects of the novel proteasome inhibitor PS-341 on activation of NF-kappa B and cell survival, growth, and angiogenesis in murine and human SCC cell lines. PS-341 inhibited activation of NF-kappa B DNA binding and functional reporter activity at concentrations between 10(-8) and 10(-7) M. Cytotoxicity was observed at 10(-7) M in four murine and two human SCC lines, and followed early cleavage of poly(ADP-ribose) polymerase, a marker of caspase-mediated apoptosis. In vivo, PS-341 inhibited growth of murine and human SCC in mice at doses of 1--2 mg/kg given three times weekly, and dose-limiting toxicity was encountered at 2 mg/kg. Tumor growth inhibition was associated with a marked decrease in vessel density. PS-341 inhibited expression of the proangiogenic cytokines growth-regulated oncogene-alpha and vascular endothelial growth factor by SCC in the range at which PS-341 inhibits NF-kappa B. We conclude that PS-341 inhibits activation of NF-kappa B pathway components related to cell survival, tumor growth, and angiogenesis in SCC.     

Increased and correlated nuclear factor-kappa B and Ku autoantigen activities are associated with development of multidrug resistance

In this study, we investigated possible engagement of NF-kappaB and Ku autoantigen (Ku) activation in development of multidrug resistance (MDR) and circumvention of MDR by modulation of NF-kappaB and Ku. The NF-kappaB activity and NF-kappaB p65 subunit level were constitutively higher in MDR cells than in drug-sensitive parental cells. Interestingly, a faster running NF-kappaB DNA binding complex was identified as Ku, a DNA damage sensor and a key double strand break repair protein, and was positively correlated with the NF-kappaB activity in MDR cells and Ku- or both subunits of NF-kappaB-transfected cells. Also both NF-kappaB and Ku activities were activated or inhibited by treatment with etoposide (VP-16) or MG-132 (a proteasome inhibitor), respectively. Furthermore, PKA inhibitor suppressed markedly the constitutive and drug-induced activities of NF-kappaB and Ku in MDR cells and subsequently potentiated the cytotoxic activity of anticancer drugs. Our results proposed that the NF-kappaB and Ku activation could be one of multi-factorial MDR mechanism, and PKA inhibitor, likely via inhibition of NF-kappaB and Ku activities, could enhance the effectiveness of anticancer drugs against MDR cells with high activities of NF-kappaB and Ku.     

Increased expression of RelA/nuclear factor-kappa B protein correlates with colorectal tumorigenesis

OBJECTIVE: To identify the role of RelA/nuclear factor-kappa B, an important inhibitor of apoptosis in colorectal tumorigenesis, we examined the expression of RelA in normal colorectal mucosa (n = 10), colorectal adenomas (n = 30) and colorectal adenocarcinomas (n = 30). Furthermore, the association of RelA expression with tumor cell apoptosis, proliferation, and expression of Bcl-2/Bcl-x(L )was also studied. METHODS: Paraffin sections were stained with monoclonal antibodies directed against RelA, Bcl-2, Bcl-x(L), and Ki-67 to assess protein expression patterns in normal, adenomatous and colon cancer tissue. Apoptotic cells were detected by terminal deoxynucleotidyl-transferase-mediated dUTP-biotin nick end labeling (TUNEL) using an in situ detection kit. RESULTS: The results of immunohistochemical staining revealed that expression of RelA, Bcl-2, Bcl-x(L), and Ki-67 labeling index (LI) significantly increased in the transition from adenoma with low dysplasia to adenocarcinoma. This transition was associated with a significant decrease in the apoptotic index (AI) and a significant increase in the Ki-67 LI. The expression of RelA correlated inversely with the AI and correlated positively with the expression of Bcl-2, Bcl-x(L), and Ki-67 LI in the transition from low-grade dysplasia to adenocarcinoma. CONCLUSION: Our results suggest that increased expression of RelA/nuclear factor-kappa B plays an important role in the transition from colorectal adenoma with low-grade dysplasia to adenocarcinoma in the pathogenesis of colon cancer in humans.     

Defective Jak-Stat activation in renal cell carcinoma is associated with interferon-alpha resistance

Chemotherapy is ineffective against metastatic renal cell carcinoma (RCC). Interferon (IFN)-alpha has become the most common agent used in clinical therapy to overcome this malignant tumor, although a satisfactory response has not been achieved and the mechanism of resistance of RCC to IFN-alpha remains unclear. The purpose of the present study was to evaluate the susceptibility of RCC cells to IFN-alpha and clarify the mechanism of IFN-alpha resistance in RCC. Six RCC cell lines and three types of IFN-alpha were used, and the expression, activation and effects of transfection of possible proteins or factors reported to be involved in IFN-alpha signaling were examined to clarify the mechanism of resistance. The results suggest that the resistance of RCC to IFN-alpha is associated with the lack of Jak1, Tyk2 and Stat1 expression and defective Jak-Stat activation, but not with a lack of IFN-alpha receptor, suppressors of cytokine signaling induction or other factors examined. Moreover, phosphorylation of Jak-Stat pathway components and reversion of IFN-alpha resistance in RCC were observed upon transfection with Jak1, Tyk2 or Stat1 vector. These results suggest that restoring the expression of Jak or Stat1 might strikingly increase the susceptibility of RCC to IFN-alpha and may be a new strategy for improving the response of RCC to IFN-alpha treatment. The Jak-Stat pathway should therefore be an appropriate target for the treatment of RCC.     

Increased interferon alpha receptor 2 mRNA levels is associated with renal cell carcinoma metastasis

Background  

Interferon-α (IFN-α) is one of the central agents in immunotherapy for renal cell carcinoma (RCC) and binds to the IFN-α receptor (IFNAR). We investigated the role of IFNAR in RCC.     

Metastatic gastric tumor from renal cell carcinoma

Metastatic tumors of the stomach are rare, with an incidence of 0.2%–0.7%, and they have been reported to result mainly from primary breast cancers, lung cancers, and melanoma. Further, among such metastatic tumors, the metastasis of renal cell carcinoma (RCC) to the stomach is an extremely rare disease, and it is usually reported in autopsy series. We report a rare case of metastatic gastric tumor derived from right renal carcinoma. Gastric endoscopy confirmed a large, polypoid, friable mass (type 1 tumor, about 7 cm in diameter) in the middle part of the stomach body. The mass was surgically excised and pathological examination showed that the gastric tumor was derived from a metastasis from the right kidney, because it was composed of malignant cells that were identical to those from the removed RCC. In addition, the tumor cells were immunoreactive for CD10, CD15, Ecadherin, early membrane antigen (EMA), and vimentin, but no reactivity was observed for cytokeratins 7 and 20 or c-KIT. Although gastric metastatic tumor derived from renal carcinoma is rare, the precise pre- and postoperative diagnosis may be important; thus, investigation for such metastatic tumors should be performed routinely in the follow up of patients who have been treated for RCC.     

Tryptophan 2,3-dioxygenase in tumor cells is associated with resistance to immunotherapy in renal cell carcinoma

Indoleamine 2,3-dioxygenase 1 (IDO1) is a key enzyme associated with immunomodulation through its regulation of the tryptophan-kynurenine (Kyn) pathway in advanced cancers, including metastatic renal cell carcinoma (mRCC). However, the failure of IDO1 inhibitors when used in combination with immune checkpoint inhibitors (ICIs), as observed in clinical trials, raises a number of questions. This study aimed to investigate the association of tryptophan 2,3-dioxygenase (TDO) and IDO1 with cancer development and resistance to immunotherapy in patients with RCC. In our analysis of RCC tissue samples, tissue Kyn levels were elevated in advanced-stage RCC and correlated well with TDO expression levels in RCC tumor cells. In patients with mRCC, TDO rather than IDO1 was expressed in RCC tumor cells, showing a strong association with Kyn expression. Furthermore, immunohistochemical staining of TDO was strongly associated with the staining intensity of forkhead box P3, as well as ICI therapy response and survival in patients with mRCC. Our study is the first to show that TDO expression in tumor tissues is associated with progression and survival, confirming its potential as a predictive biomarker of primary resistance to immunotherapy in patients with mRCC. Our findings suggest that strategies aimed at inhibiting TDO, rather than IDO1, in combination with ICI therapy may aid in the control of mRCC progression.