Uterine Cervical Cancer Cell Lines Research Articles

Enhanced Expression of Thymidylate Synthase Mediates Resistance of Uterine Cervical Cancer Cells to Radiation

It has been shown that there is an inverse relationship between the level of thymidylate synthase (TS) and therapeutic outcomes in patients with malignancies including cervical cancer. To clarify the mechanism of the poor prognosis of cervical cancer with high TS expression, we introduced TS cDNA to the human uterine cervical cancer cell line SKG-II and evaluated the effect of TS expression on its radiosensitivity. After selection, stable transformants of SKG-II cells expressing high level of TS (SKG-II/TS) and control cells (SKG-II/luciferase) were obtained. The level of TS measured by the FdUMP-TS binding assay was significantly higher (p < 0.05) in SKG-II/TS than in control (2.0 ± 0.1 and 1.3 ± 0.1 pmol/mg, respectively). No difference was observed in in vitro cell growth or in vivo tumor growth. On evaluation of in vitro radiosensitivity, the 50% growth inhibitory dose (ID₅₀) was 3.1 ± 0.1 Gy in SKG-II/TS and was significantly higher (p < 0.01) than that in control (2.2 ± 0.1 Gy). From these results, it is suggested that one of the reasons of poor outcome of cervical cancer to radiation is high TS expression.

Morphologic evaluation of the antitumor activity of photodynamic therapy (PDT) using mono-L-aspartyl chlorin e6 (NPe6) against uterine cervical carcinoma cell lines.

In order to elucidate the antitumor effect and mechanism of action of photodynamic therapy (PDT) using the photosensitizing agent mono-L-aspartyl chlorin e6 (NPe6) and a semiconductor laser, we conducted a morphologic study on uterine cervical cancer cell lines. First, tumor shrinkage was confirmed in a tumor growth inhibition test. Next, morphologic changes after PDT were examined, and since the major change appeared to be tumor necrosis secondary to obstruction of the blood vessels around the tumor, an NPe6 cell uptake experiment was performed. The results confirmed that a significantly greater amount of NPe6 was incorporated by human umbilical vein endothelial cells (HUV-EC1) and the cervical cancer cell lines than by human umbilical cord-derived fibroblasts. Based on these findings it was concluded that NPe6 possesses tumor affinity, and necrosis secondary to vascular obstruction was postulated to be the principal mechanism of the antitumor effect of PDT using NPe6.

Indomethacin increases the cytotoxicity of cis-platinum and 5-fluorouracil in the human uterine cervical cancer cell lines SKG-2 and HKUS by increasing the intracellular uptake of the agents.

Various approaches have been made to increase the cytotoxicity of cis-platinum (CDDP) and 5-fluorouracil (5FUra), and to reduce their adverse effects. We used two human cancer cell lines of the uterine cervix (SKG-2 and HKUS) and selected indomethacin as a modifying agent to assess its effect on the cytotoxicity of CDDP and 5FUra. The effect of indomethacin on the cytotoxicity of CDDP and 5FUra in these tumor cells was evaluated by in-vitro Alamar blue assay, and intracellular uptake of free-CDDP and 5FUra was measured to find out how indomethacin modified the cytotoxicity of CDDP and 5FUra. Indomethacin showed no cytotoxic effect on these tumor cells, but significantly (P < 0.005-0.001) increased the cytotoxicity of both CDDP and 5FUra, compared with single treatment by each agent. The intracellular uptake of both free-CDDP and 5FUra was measured in culture media containing the agents alone (single treatment) or the agents with indomethacin (0.001, 0.01, and 0.1 microgram/ml; combined treatment). The intracellular contents of both free-CDDP (SKG-2, HKUS; P < 0.001) and 5FUra (SKG-2; P < 0.005, HKUS; P < 0.02) were significantly higher in the combined treatment than in the single treatment. This study shows that indomethacin increased the cytotoxicity of both CDDP and 5FUra by increasing the intracellular incorporation of free-CDDP and 5FUra, and suggests the effectiveness of indomethacin in reducing the dosage of CDDP and 5FUra or increasing CDDP and 5FUra cytotoxicity when these agents are given without reducing the dose.

Expression and intracytoplasmic signal transduction pathway of fibroblast growth factor (FGF)-10 in human cervical cancer cell lines

Fibroblast growth factor (FGF) -10 is a new member of the FGF family initially reported in Japan. It is mainly synthesized by mesenchymal cells and acts on epithelial cells in a paracrine manner. FGF-10 actions are dependent on their binding to the iiib form of FGF receptor 2 (FGFR2) iiib, also known as keratinocyte growth factor receptor (KGFR). FGF-10 has high amino acid homology to keratinocyte growth factor (KGF) and plays an important role in fetal limb and lung development and skin wound healing. In the present study, the expression of FGF-10 and FGFR2 iiib messenger RNA (mRNA) in two different human uterine cervical cancer cell lines (CaSki and ME-180) were examined. Both CaSki and ME-180 cells expressed FGFR2 iiib mRNA, while only CaSki cells expressed FGF-10 mRNA and protein. Recombinant FGF-10 (1 ng/ml) increased the growth rate of ME-180 cells and also enhanced mitogen-activated protein kinase (MAPK) phosphorylation of the cells. These data indicate that FGF-10 may directly promote the growth of squamous cell cancer in the uterine cervix via the MAPK pathway.

Alteration of the CDKN2/p16 gene is not required for HPV-positive uterine cervical cancer cell lines.

To determine whether alterations of the CDKN2/p16 might be involved in HPV-positive cervical cancers, we examined for alterations of this gene and function of the protein p16 to interact with CDK4 in 5 cervical cancer cell lines. No alteration of this gene was detected. Proteins for p16 and CDK4 were normally expressed and function of p16 to interact with CDK4 was not abrogated in these cell lines. These cell lines were human papillomavirus (HPV)-positive and carried wild-type p53. These findings suggest that phosphorylation of pRb by CDK4 is not critical in the carcinogenesis or in the establishment of HPV-positive cervical cancer cell lines, since HPV E6 or E7 viral-transforming proteins inactivate p53 and pRb tumor suppressor protein function, resulting in deregulated progression of the cell cycle.

Sensitization of human uterine cervical cancer cells to radiation using paclitaxel

The effect of paclitaxel on the in vitro radiation sensitivity of the uterine cervical cancer cell line SKG IIIa was studied in vitro. Three-hour incubation of cells in low-concentration paclitaxel (3 nmol/L), which has little suppressive activity on cell growth, for 3 hours 48 hours before irradiation at 1.5 Gy, produced a cell growth-suppressing effect that was statistically significant compared with that produced by 1.5 Gy irradiation alone. Cell cycle analysis demonstrated a temporary increase in the number of S phase cells after paclitaxel administration, but no G 2 or M phase blocking. Although the mechanism by which paclitaxel sensitizes these cells to radiation in vitro is not known, results suggest that paclitaxel may be clinically useful as a radiosensitizer in the treatment of uterine cervical cancer and should be further evaluated.

Preclinical analysis of the antitumor efficacy of TS-1 using human uterine cervical cancer tumor xenografts

We investigated the antitumor activity of TS-1 in comparison with that of UFT and cisplatin (CDDP) against cervical cancer using xenografts of a human uterine cervical squamous cell cancer cell line, CaSki, transplanted into female Balb/cA JcL-nu mice. CaSki cell xenografts were prepared by subcutaneous (s.c.) implantation of 3x10(6) cells/animal into the right dorsal region of the mice. The tumor volume was measured twice a week and the relative tumor volume (RTV) was calculated. We divided the animals into four groups according to the treatment administered; TS-1 (10 mg/kg orally, once daily for 14 consecutive days), UFT (24 mg/kg orally, once daily for 14 consecutive days), CDDP (7.6 mg/kg injected intravenously once on the 1st day) and control (no treatment) groups. The antitumor effects of the drugs were measured. On the 35th day after the completion of treatment, the mean tumor volume in the mice treated with TS-1 or CDDP changed from 132.873+/-11.783 mm(3) to 706.401+/-613.122 mm(3) and 133.809+/-19.366 mm(3) to 722.630+/-855.509 mm(3), respectively. The mean tumor volume in the groups treated with TS-1 or CDDP was significantly lower compared to that in the control group (p<0.001; one-tailed Student's t-test). The relative inhibition of the tumor growth was 65.31 in the TS-1 group, 48.31 in the UFT group and 64.51 in the CDDP group. We conclude that TS-1 administered orally for 14 consecutive days showed the highest antitumor activity.

In vitro and in vivo Induction of Squamous Cell Carcinoma Antigen (SCC) in a Uterine Cervical Cancer Cell Line (SKG‐IIIa) with Peplomycin and Sodium Butyrate

In order to investigate the effect of an antisquamous cell carcinoma drug, peplomycin, the new analogue of bleomycin, on the production of a squamous cell carcinoma-associated tumor marker termed "SCC" (or TA-4), we carried out in vitro and in vivo experiments using the uterine cervical epidermoid cancer cell line SKG-IIIa, together with the investigation of the effect of sodium butyrate which was reported to be one of the representative gene modulators. In vitro production of SCC was biochemically and immunocytochemically confirmed in SKG-IIIa cells. Immunocytochemistry using anti-SCC antibody revealed that the total number of SCC-positive cells increased after the treatment with peplomycin (1.6 fold) or sodium butyrate (1.5 fold). The total amount of SCC in cultured medium, intracellular SCC, and cell debris during 5 days of culturation also increased with peplomycin (1.8 fold) and sodium butyrate (1.4 fold). These data strongly suggest that SCC production of SKG-IIIa cells is stimulated by peplomycin and sodium butyrate in vitro. In vivo experiments were also performed by administering peplomycin to nude rats with heterotransplanted tumors of SKG-IIIa, and transient elevations of serum SCC level (113% to 238% of the initial values) were observed, suggesting that SCC production of cancer cells is also stimulated by peplomycin in vivo.

The mechanism of placental alkaline phosphatase induction in vitro.

The mechanism of placental alkaline phosphatase (PLAP) induction by prednisolone in a uterine cervical epidermoid cancer cell line SKG-IIIa was investigated in vitro by enzyme-cytochemistry, enzyme immunoassay, Northern and Southern blot analysis, and in situ hybridization. Enzyme-cytochemical alkaline phosphatase (ALP) staining and immunoassay revealed increased levels of PLAP (heat-stable ALP) in prednisolone-treated cells. Northern blot analysis and in situ hybridization showed increased amounts of PLAP mRNA. Southern blot analysis indicated that PLAP was not a product of an amplified or rearranged gene. These findings suggest that the induction of PLAP mRNA in SKG-IIIa cells by prednisolone in turn increased the levels of PLAP.

Sodium butyrate produces concordant expression of "early placental" alkaline phosphatase, pregnancy-specific beta 1-glycoprotein and human chronic gonadotropin beta-subunit in a newly established uterine cervical cancer cell line (SKG-IIIa).

The production of early and term placental alkaline phosphatase (ALP), human chorionic gonadotropin beta-subunit (beta-hCG) and pregnancy-specific beta 1-glycoprotein (SP1) was confirmed in the newly established uterine cervical cancer call line SKG-IIIa. Treatment of these cells in culture with sodium butyrate caused an increase of all of these oncodevelopmental proteins. On the other hand, prednisolone treatment enhanced only term placental ALP, while it reduced early placental ALP, beta-hCG and SP1. These data suggested that such oncotrophoblastic proteins as early placental ALP, beta-hCG and SP1 were concordantly modulated by butyrate and prednisolone. These findings may support the possibility of the reexpression of sets of development phase-specific genes in cancer cells.