Drosophila lethal giant larvae (lgl), discs large (dlg) and scribble (scrib) are tumour suppressor genes acting in a common pathway, whose loss of function leads to disruption of cell polarity and tissue architecture, uncontrolled proliferation and growth of neoplastic lesions. Mammalian homologues of these genes are highly conserved and evidence is emerging concerning their role in cell proliferation control and tumorigenesis in humans. Here we investigate the functional conservation between Drosophila lethal giant larvae and its human homologue Hugl-1(Llgl1). We first show that Hugl-1 is lost in human solid malignancies, supporting its role as a tumour suppressor in humans. Hugl-1 expression in homozygous lgl Drosophila mutants is able to rescue larval lethality; imaginal tissues do not show any neoplastic features, with Dlg and Scrib exhibiting the correct localization; animals undergo a complete metamorphosis and hatch as viable adults. These data demonstrate that Hugl-1 can act as a tumour suppressor in Drosophila and thus is the functional homologue of lgl. Furthermore, our data suggest that the genetic pathway including the tumour suppressors lgl, dlg and scrib may be conserved in mammals, since human scrib and mammalian dlg can also rescue their respective Drosophila mutations. Our results highlight the usefulness of fruit fly as a model system for investigating in vivo the mechanisms linking loss of cell polarity and cell proliferation control in human cancers.

The human gene Hugl-1 (Llgl/Lgl1) has significant homology to the Drosophila tumor suppressor gene lethal(2)giant larvae (lgl). The lgl gene codes for a cortical cytoskeleton protein, Lgl, that is involved in maintaining cell polarity and epithelial integrity. We speculate that Hugl-1 might play a role in epithelialmesenchymal transition (EMT) and that loss of Hugl-1 expression plays a role in the development or progression of malignant melanoma. Thus, we evaluated melanoma cell lines and tissue samples of malignant melanoma for loss of Hugl-1 transcription. We found that Hugl-1 was downregulated or lost in all cell lines and in most of the tumor samples analysed, and that these losses were associated with advanced stage of the disease. Reduced Hugl-1 expression occurred as early as in primary tumors detected by both immunohistochemical and reverse transcription-polymerase chain reaction (RT-PCR) analysis. Functional assays with stable Hugl-1-transfected cell lines revealed that Hugl-1 expression increased cell adhesion and decreased cell migration. Further, downregulation of MMP2 and MMP14 (MT1-MMP) and re-expression of E-cadherin was found in the Hugl-1-expressing cell clones supporting a role of Hugl-1 in EMT. Our studies thus indicate that loss of Hugl-1 expression contributes to melanoma progression.

The addition of sorafenib to gemcitabine did not demonstrate improved efficacy in advanced BTC patients. Biomarker subgroup analysis suggested that some patients might benefit from combined treatment.

IFNs are pleiotropic cytokines that have been shown to be important regulators of cell growth. IFN-A has recently been recognized to harbor therapeutic potential in prevention and treatment of hepatocellular carcinoma (HCC). However, HCC cells respond differentially to IFN treatment, the mechanism of which is largely unknown. To address this issue, we analyzed the effect of IFN-A on different liver tumor cell lines. We found that growth inhibiting effects of IFN-A in hepatoma cells require PML-NB induction and, moreover, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) expression on the mRNA and protein level.

and immunohistochemistry. Bcl-x L and Mcl-1 protein expression was knocked down or increased in CRC cell lines by applying specific siRNAs or expression plasmids, respectively. After modulation of protein expression, CRC cells were treated with chemotherapeutic agents, an antagonistic epidermal growth factor receptor (EGFR1) antibody, an EGFR1 tyrosine kinase inhibitor, or with the death receptor ligand TRAIL. Apoptosis induction and cell viability were analyzed. RESULTS: Here we show that in human CRC tissue and various CRC cell lines both Bcl-x L and Mcl-1 are expressed. Bcl-x L expression was higher in CRC tissue than in surrounding non-malignant tissue, both on protein and mRNA level. Mcl-1 mRNA expression was significantly lower in malignant tissues. However, protein expression was slightly higher. Viability rates of CRC cells were significantly decreased after knock down of Bcl-x L expression, and, to a lower extent, after knock down of Mcl-1 expression. Furthermore, cells with reduced Bcl-x L or Mcl-1 expression was more sensitive towards oxaliplatin-and irinotecan-induced apoptosis, and in the case of Bcl-x L also towards 5-FU-induced apoptosis. On the other hand, upregulation of Bcl-x L by transfection of an expression plasmid decreased chemotherapeutic drug-induced apoptosis. EGF treatment clearly induced Bcl-x L and Mcl-1 expression in CRC cells. Apoptosis induction upon EGFR1 blockage by cetuximab or PD168393 was increased by inhibiting Mcl-1 and Bcl-x L expression. More strikingly, CD95-and TRAIL-induced apoptosis was increased by Bcl-x L knock down. CONCLUSION: Our data suggest that Bcl-x L and, to a lower extent, Mcl-1, are important anti-apoptotic factors in CRC. Specific downregulation of Bcl-x L is a promising approach to sensitize CRC cells towards chemotherapy and targeted therapy.

Although 5-fluorouracil remains the mainstay of treatment for advanced gastric cancer (AGC), no standard chemotherapy regimen exists. Combinations of irinotecan with folinic acid and infusional 5-fluorouracil (5-FU) (ILF) have shown good efficacy with acceptable toxicity in patients with metastatic colorectal cancer. At present, only sparse data on ILF are available for AGC. Therefore we conducted a prospective study of this combination in 25 consecutive patients with metastatic gastric cancer. Median age was 63 years, 10 had received prior chemotherapy and 13 presented initially with peritoneal carcinosis. Treatment consisted of irinotecan 80 mg/m2, folinic acid 500 mg/m2 and infusional 5-FU 2.0 g/m2 over 24 h, given weekly for 6 weeks followed by a 1-week rest. Grade 3/4 hematologic toxicity occurred in six patients (anemia = 4, neutropenia = 1 and leukopenia = 1). Non-hematologic toxicity consisted mainly of nausea/vomiting (grade 3/4 in six patients) and diarrhea (grade 3/4 in 10 patients). The overall response rate was 20% for first- and second-line treatment, with two complete and three partial responses. Another nine patients (36%) had stable disease, for a tumor control rate of 56%. Median time to progression was 4 months, median overall survival and survival for patients with tumor control was 7 and 13 months, respectively. We conclude that ILF is a feasible outpatient regimen with manageable toxicity that provides tumor control in a high proportion of patients with advanced gastric cancer, even among those with unfavorable prognostic features.

Hepatic DTC in colorectal cancer patients is associated with reduced overall survival and increased risk of hepatic metastasis development. Further studies are necessary to corroborate our results since the number of patients studied is still limited.

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