Squamous Carcinoma Cell Line SCC-25 Research Articles

Role of protein kinase D1 in regulating the growth, apoptosis and drug sensitivity of oral squamous carcinoma cells

This study aimed to investigate the role of protein kinase D (PKD)1 in regulating the growth, apop-tosis, and drug sensitivity of the squamous carcinoma cell line SCC-25. The SCC-25 cell line was transfected with either the control-shRNA or PKD1-shRNA plasmids. The stable transfected cells were selected, and the efficiency of PKD1 knockdown was detected by Western blot. The growth and apoptosis of SCC-25 were analyzed with a cell counting kit-8 (CCK8) and flow cytometry. The 50% inhibitory concentrations (IC50) of paclitaxel in the control and PKD1 knockdown cell lines were detected by CCK-8. The expression levels of Bax, Bcl-2, and P-gp were detected by Western blot. PKD1 was constitutively expressed and phosphorylated in various cancer cell lines. Inhibiting the expression of PKD1 in SCC-25 cells by RNA interference could inhibit the growth and promote the apoptosis of SCC-25 cells via downregulating Bcl-2 expression. Additionally, inhibiting PKD1 expression could downregulate the expression of P-gp, thereby decreasing both the IC50 and resistance index of paclitaxel. PKD1 plays an important role in regulating the biobehavior of SCC-25. It is a potential therapeutic target for oral squamous carcinoma.

Pre-exposure of human squamous carcinoma cells to low-doses of gamma-rays leads to an increased resistance to subsequent low-dose cisplatin treatment

Purpose: To investigate low-dose hypersensitivity to cisplatin and increased resistance at higher doses of cisplatin for the human squamous carcinoma cell line SCC-25 and its cisplatin-resistant derivative SCC-25/CP, and to examine the effects of pre- and post-treatment of SCC-25 cells with low-doses of gamma-rays on their resistance to cisplatin. Materials and methods: SCC-25 and SCC-25/CP cells were treated with various cisplatin concentrations (0.1 to 20 mu m for 1h) and assayed for survival using a conventional colony assay. For SCC-25, various doses of gamma-rays (5cGy to 2.5Gy) were given either 10 or 60min before the cisplatin challenge dose as well as either 10 or 60min after the cisplatin challenge dose. Results: Low-dose (0.5, 0.75 and 1 mu m for 1h) hypersensitivity to cisplatin and increased resistance at higher doses was detected for the SCC-25 cell line, but not for its cisplatin-resistant derivative, SCC-25/CP. Pretreatment of SCC-25 cells with an acute low-dose of 5, 25cGy or 1Gy gamma -rays given 60min before a low-dose cisplatin challenge (0.1 and 1 mu m for 1h) resulted in a significant increase in resistance (p=0.2, 0.01 and < 0.001 respectively). For pretreatment of SCC-25 cells with similar lowdoses of gamma-rays 10min before the challenge cisplatin dose, the increased resistance was reduced or absent and was only significantly increased for pretreatment with 25cGy and a challenge cisplatin dose of 0.1 mu m for 1h (p=0.02). Similar acute low-doses of gamma-rays given either 10 or 60min after the challenge cisplatin dose did not increase resistance. Conclusions: The human squamous carcinoma cell line SCC-25 showed a low-dose hypersensitivity to cisplatin followed by increased resistance at higher doses. Treatment of SCC-25 cells with low-doses of gamma-rays can induce a protective effect to a subsequent low-dose cisplatin challenge.

Synthesis and potent antifolate activity and cytotoxicity of B-ring deaza analogues of the nonpolyglutamatable dihydrofolate reductase inhibitor Nalpha-(4-amino-4-deoxypteroyl)-Ndelta-hemiphthaloyl- L-ornithine (PT523).

Six new B-ring analogues of the nonpolyglutamatable antifolate Nalpha-(4-amino-4-deoxypteroyl)-Ndelta-hemiphthaloy l-L-ornithine (PT523, 3) were synthesized with a view to determining the effect of modifications at the 5- and/or 8-position on dihydrofolate reductase (DHFR) binding and tumor cell growth inhibition. The 5- and 8-deaza analogues were prepared from methyl 2-L-amino-5-phthalimidopentanoate and 4-amino-4-deoxy-N10-formyl-5-deaza- and -8-deazapteroic acid, respectively. The 5,8-dideaza analogues were prepared from methyl 2-L-[(4-aminobenzoyl)amino]-5-phthalimidopentanoate and 2, 4-diaminoquinazoline-6-carbonitriles. The Ki for inhibition of human DHFR by the 5-deaza and 5-methyl-5-deaza analogues was about the same as that of 3 (0.35 pM), 11-fold lower than that of aminopterin (AMT, 1), and 15-fold lower than that of methotrexate (MTX, 2). However the Ki of the 8-deaza analogue was 27-fold lower than that of 1, and that of the 5,8-dideaza, 5-methyl-5,8-dideaza, and 5-chloro-5,8-dideaza analogues was approximately 50-fold lower. This trend was consistent with the published literature on the corresponding DHFR inhibitors with a glutamate side chain. In colony formation assays against the human head and neck squamous carcinoma cell line SCC25 after 72 h of treatment, the 5- and 8-deaza analogues were approximately as potent as 3, whereas the 5,8-dideaza analogue was 3 times more potent. 5-Methyl and 5-chloro substitution was also favorable, with the 5-methyl-5-deaza analogue being 2. 5-fold more potent than the 5-deaza analogue. However the effect of 5-methyl substitution was less pronounced in the 5,8-dideaza analogues than in the 5-deaza analogues. The 5-chloro-5,8-dideaza analogue of 3 was the most active member of the series, with an IC50 = 0.33 nM versus 1.8 nM for 3 and 15 nM for MTX. The 5-methyl-5-deaza analogue of 3 was also tested at the National Cancer Institute against a panel of 50 human tumor cell lines in culture and was consistently more potent than 3, with IC50 values in the low-nanomolar to subnanomolar range against most of the tumors. Leukemia and colorectal carcinoma cell lines were generally most sensitive, though good activity was also observed against CNS tumors and carcinomas of the breast and prostate. The results of this study demonstrate that B-ring analogues of 3 inhibit DHFR activity and tumor cell colony formation as well as, or better than, the parent compound. In view of the fact that 3 and its B-ring analogues cannot form polyglutamates, their high cytotoxicity relative to the corresponding B-ring analogues of AMT is noteworthy.

Modulation of cisplatin sensitivity and accumulation by interferon α‐2A in human squamous carcinoma cell lines

This study was undertaken to elucidate the mechanism(s) of potentiation of cisplatin (CDDP) cytotoxicity by interferon alpha-2a (IFN alpha-2a) in human squamous carcinoma cell lines SCC-25 and SCC-4. IFN alpha-2a treatment significantly increased the cytotoxicity of CDDP in both cell lines in a dose-dependent manner. In SCC-25 cells, the cytotoxicity of CDDP was increased by about 2- and 4-fold, respectively, by treating the cells with 400 and 800 IU/ml IFN alpha-2a. Sensitivity of SCC-4 cells to CDDP was increased by about 3- and 7-fold, respectively, by 400 and 800 IU/ml IFN alpha-2a treatment. Drug uptake experiments revealed approximately 1.4- to 5-fold higher platinum accumulation in IFN alpha-2a-treated cells as compared to respective controls. Cellular levels of glutathione (GSH) and GSH transferase, which have been suggested to be important determinants of tumor cell sensitivity to CDDP, were not altered by IFN alpha-2a treatment in either of the cell lines. Northern blot analysis showed a moderate increase (about 30-40%) in the level of MT-IIA mRNA by IFN alpha-2a treatment in these cells. Our results suggest that IFN alpha-2a-mediated sensitization of SCC-25 and SCC-4 cell lines to CDDP in vitro may be due to an increase in intracellular platinum accumulation.

Comparison of the inhibitory effect of polyunsaturated fatty acids on prostaglandin synthesis. II. Fibroblasts

In a previous publication (1) we reported that PUFAs of the n-6 and n-3 series caused significant inhibition of synthesis of both PGE 2 (28.4–92.8%) and PGF 2α (24.4–84.0%) in the oral squamous carcinoma cell line SCC-25. In this report we describe the inhibitory effect of the same acids on PG synthesis in normal human gingival fibroblasts under the same experimental conditions. It was found that a combination of EPA + DCHA (6:4), DCHA and ALA caused significant reduction in synthesis of PGE 2 (10.1–87.8%) and PGF 2α (14.0–54.6%) at the four dose levels studied. The rank order of potency of acids in reduction of PG synthesis was: EPA + DCHA>DCHA>EPA>ALA>LA>DGLA>GLA. The data suggest that although PUFAs are effective inhibitors of PG synthesis by gingival fibroblasts and SCC-25, the fibroblast is less susceptible to the inhibitory effect of fatty acids.