Resveratrol has been reported to exert anticancer activity via modulation of multiple pathways and genes. In this study, we examined the effect of resveratrol on YD-10B human oral squamous cell carcinoma cells and its molecular mechanisms of action. We found that resveratrol inhibited the proliferation of YD-10B cells in a dose- and timedependent manner. The suppressive effect of resveratrol was accompanied by a reduction in Bmi-1 gene expression. We observed that silencing the Bmi-1 gene by small interfering RNA effectively downregulated the levels of GLUT1 mRNA and protein, which were also repressed by resveratrol. Bmi-1 silencing increased the number of YD-10B cells in S-phase arrest by approximately 2.3-fold compared with the control. In conclusion, the results of the present study demonstrate, for the first time, that resveratrol suppresses Bmi-1-mediated GLUT1 expression in human oral squamous cell carcinoma cells and suggest that the specific molecular targeting of Bmi-1 and/or GLUT1 expression can be combined with a chemotherapeutic strategy to improve the response of oral cancer cells to resveratrol.

Bilobalide isolated from the leaves of Ginkgo biloba has several pharmacological activities such as neuroprotective, anti-inflammatory, and anticonvulsant. However, the effect of bilobalide on cancer has not been clearly established. The main purpose of this study was to investigate the effect of bilobalide on cell growth and apoptosis induction in FaDu human pharyngeal squamous cell carcinoma. This was examined by 3-[4,5-dimethylthiazol-2-yl]-2,5- diphenyltetrazolium bromide assay, nuclear 4′,6-diamidino-2-phenylindole dihydrochloride staining, DNA fragmentation analysis, and immunoblotting. Bilobalide inhibited the growth of FaDu cells in dose- and time-dependent manners. Treatment with bilobalide resulted in nuclear condensation and DNA fragmentation in FaDu cells. Furthermore, it promoted the proteolytic cleavage of procaspase-3/-7/-8/-9 with increase in the amount of cleaved caspase-3/-7/-8/-9. Bilobalide-induced apoptosis in FaDu cells was mediated by the expression of Fas and the activation of caspase-8, caspase-3, and poly (ADP-ribose) polymerase. Immunoblotting revealed that the antiapoptotic mitochondrial protein Bcl-2 was downregulated, but the proapoptotic protein Bax was upregulated by bilobalide in FaDu cells. Bilobalide significantly increased Bax/Bcl-2 ratio. These results suggest that bilobalide inhibits cell proliferation and induces apoptosis in FaDu human pharyngeal squamous cell carcinoma via both the death receptor-mediated extrinsic apoptotic pathway and the mitochondrial-mediated intrinsic apoptotic pathway.

Codium fragile (Suringar) Hariot is an edible green seaweed that belong to the Codiaceae family and has been used in Oriental medicine for the treatment of enterobiasis, dropsy, and dysuria. Methanol extract of codium fragile has anti-oxidant, anti-inflammatory and anti-cancer properties, although the anti-cancer effect on oral cancer has not yet been reported. In this study, we investigated the anti-cancer activity and the mechanism of cell death by methanol extracts of Codium fragile (MeCF) on human FaDu hypopharyngeal squamous carcinoma cells. Our data showed that MeCF inhibits cell viability in a dose-dependent manner, and markedly induced apoptosis, as determined by the MTT assay, Live/Dead assay, and DAPI stain. In addition, MeCF induced the proteolytic cleavage of procaspase -3, -7, -9 and poly(ADP-ribose) polymerase(PARP), and upregulated or downregulated the expression of mitochondrial-apoptosis factor, Bax(pro-apoptotic factor), and Bcl-2(anti-apoptotic factor), . Futhermore, MeCF induced a cell cycle arrest at the G1/S phase through suppressing the expression of the cell cycle cascade proteins, p21, CDK4, CyclinD1, and phospho-Rb. Taken together, these results indicated that MeCF inhibits cell growth, and this inhibition is mediated by caspase- and mitochondrial-dependent apoptotic pathways through cell cycle arrest at the G1/S phase in human FaDu hypopharyngeal squamous carcinoma cells. Therefore, methanol extracts of Codium fragile can be provided as a novel chemotherapeutic drug due to its growth inhibition effects and induction of apoptosis in human oral cancer cells.

Anthricin (Deoxypodophyllotoxin), a naturally occurring flavolignan, has well known anti-cancer properties in several cancer cells, such as prostate cancer, cervical carcinoma and pancreatic cancer. However, the effects of Anthricin are currently unknown in oral cancer. We examined the anticancer effect and mechanism of action of Anthricin in human FaDu hypopharyngeal squamous carcinoma cells. Our data showed that Anthricin inhibits cell viability in a dose- and time-dependent manner (IC50 50 nM) in the MTT assay and Live & Dead assay. In addition, Anthricin treated FaDu cells showed marked apoptosis by DAPI stain and FACS. Furthermore, Anthricin activates anti-apoptotic factors such as caspase-3, -9 and poly (ADP-ribose) polymerase (PARP), suggesting that caspase-mediated pathways are involved in Anthricin- induced apoptosis. Anthricin treatment also leads to accumulation of the pro-apoptotic factor Bax, followed by inhibition of cell growth. Taken together, these results indicate that Anthricn-induced cell death of human FaDu hypopharyngeal squamous carcinoma cells is mediated by mitochondrial-dependent apoptotic pathway. In summary, our findings provide a framework for further exploration on Anthricin as a novel chemotherapeutic drug for human oral cancer.

OSCC is currently the most common malignancy of the head and neck, affecting tens of thousands of patients per year worldwide. Natural flavonoids from plants are potential sources for novel anti-cancer drugs. Icariin is the active ingredient of flavonol glycoside, which is derived from the medical plant Herba Epimedii. A metabolite of icariin, icariside II exhibits a variety of pharmacological actions, including anti-rheumatic, anti-depressant, cardiovascular protective, and immunomodulatory functions. However, the exact mechanism causing the apoptosis-inducing effect of icariside II in OSCC is still not fully understood. In the present study, we assessed the anti-cancer effect of icariside II in OSCC cell lines by measuring its effect on cell viability, cell proliferation, and mitochondria membrane potential (MMP). Icariside II treatment of OSCC cells resulted in a dose- and time-dependent decrease in cell viability. Hoechst staining indicated apoptosis in icariside II-treated HSC cells. Icariside II inhibited cell proliferation and induced apoptosis in HSC cells, with significant increases in all present parameters in HSC-4 cells. The results clearly suggested that icariside II induced apoptosis via activation of intrinsic pathways and caspase cascades in HSC-4 cell lines. The collective findings of the study suggested that Icariside II is a potential treatment for OSCC; in addition, the data could provide a basis for the development of a novel anti-cancer strategy.

Shikonin, a major ingredient in the traditional Chinese herb Lithospermumerythrorhizon, exhibits multiple biological functions including antimicrobial, anti-inflammatory, and antitumor effects. It has recently been reported that shikonin displays antitumor properties in many cancers. This study was aimed to investigate whether shikonin could inhibit oral squamous carcinoma cell (OSCC) growth via mechanisms of apoptosis and cell cycle arrest. The effects of shikonin on the viability and growth of OSCC cell line, SCC25 cells were assessed by MTT assay and clonogenic assays, respectively. Hoechst staining and DNA electrophoresis indicated that the shikonin-treated SCC25 cells were undergoing apoptosis. Western blotting, immunocytochemistry, confocal microscopy, flow cytometry, MMP activity, and proteasome activity also supported the finding that shikonin induces apoptosis. Shikonin treatment of SCC25 cells resulted in a time- and dose-dependent decrease in cell viability, inhibition of cell growth, and increase in apoptotic cell death. The treated SCC25 cells showed several lines of apoptotic manifestation as follows: nuclear condensation; DNA fragmentation; reduced MMP and proteasome activity; decrease in DNA contents; release of cytochrome c into cytosol; translocation of AIF and DFF40 (CAD) onto the nuclei; a significant shift in Bax/Bcl-2 ratio; and activation of caspase-9, -7, -6, and -3, as well as PARP, lamin A/C, and DFF45 (ICAD). Shikonin treatment also resulted in down-regulation of the G1 cell cycle-related proteins and up-regulation of p27KIP1. Taken together, our present findings demonstrate that shikonin strongly inhibits cell proliferation by modulating the expression of the G1 cell cycle-related proteins, and that it induces apoptosis via the proteasome, mitochondria, and caspase cascades in SCC25 cells.

Fluoride has been accepted as an important material for oral health and is widely used to prevent dental caries in dentistry. However, its safety is still questioned by some. Autophagy has been implicated in cancer cell survival and death, and may play an important role in oral cancer. This study was undertaken to examine whether sodium fluoride (NaF) modulates autophagy in SCC25 human tongue squamous cell carcinoma cells. NaF demonstrated anticancer activity via autophagic and apoptotic cell death. Autophagic vacuoles were detectable using observed to form by monodansylcadaverine (MDC) and acridine orange (AO). Analysis of NaF-treated SCC25 cells for the presence of biochemical markers revealed direct effects on the conversion of LC-3II, degradation of p62/SQSTM1, cleavage formation of ATG5 and Beclin-1, and caspase activation. NaF-induced cell death was suppressed by the autophagy inhibitor 3-methyladenine (3-MA). NaF-induced autophagy was confirmed as a pro-death signal in SCC25 cells. These results implicate NaF as a novel anticancer compound for oral cancer therapy.

Curcumin is a widely used flavoring agent in food, and it has been reported to inhibit cell growth, to induce apoptosis, and to have antitumor activity in many cancers. Cisplatin is one of the most potent known anticancer agents and shows significant clinical activity against a variety of solid tumors. This study was undertaken to investigate the synergistic apoptotic effects of co-treatment with curcumin and cisplatin on human tongue SCC25 cells. To investigate whether the co-treatment efficiently reduced the viability of the SCC25 cells compared with the two treatments separately, an MTT assay was conducted. The induction and the augmentation of apoptosis were confirmed by DNA electrophoresis, Hoechst staining, and an analysis of DNA hypoploidy. Western blot, MMP and immunofluorescence tests were also performed to evaluate the expression levels and the translocation of apoptosis-related proteins following the co-treatment. In this study, following the co-treatment with curcumin and cisplatin, the SCC25 cells showed several forms of apoptotic manifestation, such as nuclear condensation, DNA fragmentation, reduction of MMP, increased levels of Bax, decreased levels of Bcl-2, and decreased DNA content. In addition, they showed a release of cytochrome c into the cytosol, translocation of AIF and DFF40 (CAD) to the nuclei, and activation of caspase-7, caspase-3, PARP, and DFF45 (ICAD). In contrast, separate treatments of 5 μM of curcumin or 4 μg/ml of cisplatin, for 24 hours, did not induce apoptosis. Therefore, our data suggest that combination therapy with curcumin and cisplatin could be considered as a novel therapeutic strategy for human oral squamous cell carcinoma.

Several studies have shown that curcumin, which is derived from the rhizomes of turmeric, possesses antimicrobial, antioxidant and anti-inflammatory properties. The antitumor properties of curcumin have also now been demonstrated more recently in different cancers. This study was undertaken to investigate the modulation of cell cycle-related proteins and the mechanisms underlying apoptosis induction by curcumin in the SCC25 human tongue squamous cell carcinoma cell line. Curcumin treatment of the SCC25 cells resulted in a time- and dose-dependent reduction in cell viability and cell growth, and onset of apoptotic cell death. The curcumin-treated SCC25 cells showed several types of apoptotic manifestations, such as nuclear condensation, DNA fragmentation, reduced MMP and proteasome activity, and a decreased DNA content. In addition, the treated SCC25 cells showed a release of cytochrome c into the cytosol, translocation of AIF and DFF40/CAD into the nuclei, a significant shift in the Bax/Bcl-2 ratio, and the activation of caspase-9, caspase-7, caspase-6, caspase-3, PARP, lamin A/C, and DFF45/ICAD. Furthermore, curcumin exposure resulted in a downregulation of G1 cell cycle-related proteins and upregulation of p27KIP1. Taken together, our findings demonstrate that curcumin strongly inhibits cell proliferation by modulating the expression of G1 cell cycle-related proteins and inducing apoptosis via proteasomal, mitochondrial, and caspase cascades in SCC25 cells.

Cruciferous vegetables including diindolylmethane (DIM) have been shown to have anticancer activity. Especially, DIM-pPhBr and DIM-pPhF used in this study was reported to have more effective and less toxic effects than DIM. However, there is no report presenting their anti-tumorigenic activity in oral cancer. In the present study, we examined the effects of DIM-pPhBr and DIM-pPhF on the cell proliferation and apoptosis in KB human oral cancer cells. DIM-pPhBr and DIM-pPhF decreased cell proliferation and induced apoptosis evidenced by western blot analysis, DAPI staining and sub-G1 population. This provides the first evidence that DIM-pPhBr and DIM-pPhF originating from cruciferous vegetables induce apoptotic cell death in human oral cancer cells to inhibit cancer cell proliferation.

Few studies have evaluated the apoptosis-inducing efficacy of NaF on cancer cells in vitro but there has been no previous investigation of the apoptotic effects of NaF on human oral squamous cell carcinoma cells. In this study, we have investigated the mechanisms underlying the apoptotic response to NaF treatment in the YD9 human squamous cell carcinoma cell line. The viability of YD9 cells and their growth inhibition were assessed by MTT and clonogenic assays, respectively. Hoechst staining, DNA electrophoresis and TUNEL staining were conducted to detect apoptosis. YD9 cells were treated with NaF, and western blotting, immunocytochemistry, confocal microscopy, FACScan flow cytometry, and MMP and proteasome activity assays were performed sequentially. The NaF treatment resulted in a time- and dose-dependent decrease in YD9 cell viability, a dose-dependent inhibition of cell growth, and the induction of apoptotic cell death. The apoptotic response of these cells was manifested by nuclear condensation, DNA fragmentation, the reduction of MMP and proteasome activity, a decreased DNA content, the release of cytochrome c into the cytosol, the translocation of AIF and DFF40 (CAD) into the nucleus, a significant shift of the Bax/Bcl-2 ratio, and the activation of caspase-9, caspase-3, PARP, Lamin A/C and DFF45 (ICAD). Furthermore, NaF treatment resulted in the downregulation of G1 cell cyclerelated proteins, and upregulation of p53 and the Cdk inhibitor p27KIP1. Taken collectively, our present findings demonstrate that NaF strongly inhibits YD9 cell proliferation by modulating the expression of G1 cell cycle-related proteins and inducing apoptosis via mitochondrial and caspase pathways.

Oral squamous cell carcinoma (SCC) is one of the leading causes of cancer mortality worldwide. It is generally thought that adjuvant chemotherapy provides modest prolongation of survival in various carcinoma. Docetaxel (Taxotere, TXT) play a significant role in the treatment of various solid tumors of epithelial origin. CsA (immunosuppressive drug) was widely used as adjunct for the treatment of cancer. Thus, it is important to pursue the apoptosis of IHOK and oral SCC induced by TXT combined with CsA related to the pathogenesis of oral SCC. But TXT combined CsA effect on IHOK and oral SCC remains unclear. After cultured IHOK and HN 22 oral squamous cell carcinoma cell line treated by 10 nM TXT and 1 μM, and caspase inhobitor, respectively, apoptosis index, cytochrome c and caspase-3 -8, -9 mRNA expression by RT-PCR, and procaspase-3 protein amount by immunoslot blotting was prepared. The purpose of this study were to examine the TXT-induced apoptosis pathway via caspase activation by CsA enhancement, and to apply these results to an effective therapeutic treatment plan for oral SCC by TXT combined CsA . 10 nM TXT showed about 60%, 55% celluar apoptosis of IHOK and HN 22, cell line, respectively, while CsA alone did not induce apoptosis in IHOK and HN 22 cell line. 1 μM CsA combined with 10 nM TXT increased apoptosis in IHOK and HN 22 cell line through caspase-3 and cytochrome c mRNA expression, while could not effect on caspase-8 and -9. Caspase inhibitor suppressed apoptosis of IHOK and HN 22 cell line induced by a combination of 1 μM CsA and 10 nM TXT. Immnoslot blotting showed procaspase-3 activation by a combination 1 μM CsA and 10 nM TXT, while caspase inhibitor inhibited activation. It suggested that a combination of CsA and TXT might induce increased apoptosis of IHOK and HN 22 oral squamous cell carcinoma cell line through caspase-3 activation. This treatment with a combination of TXT and CsA may be an effective therapeutic strategy for oral squamous cell carcinoma

Cytosolic Ca2+ is an important regulator of tumor cell proliferation and metastasis. Recently, the strategy of blocking receptors and channels specific to certain cancer cell types has emerged as a potentially viable future treatment. Oral squamous cell carcinoma is an aggressive form of cancer with a high metastasis rate but the receptor-mechanisms involved in Ca2+ signaling in these tumors have not yet been elucidated. In our present study, we report that bradykinin induces Ca2+ signaling and its modulation in the human oral squamous carcinoma cell line, HSC-3. Bradykinin was found to increase the cytosolic Ca2+ levels in a concentration-dependent manner. This increase was inhibited by pretreatment with the phospholipase C-β inhibitor, U73122, and also by 2-aminoethoxydiphenyl borate, an inhibitor of the inositol 1,4,5-trisphosphate receptor. Pretreatment with extracellular ATP also inhibited the peak bradykinin-induced Ca2+ rise. In contrast, the ATP-induced rise in cytosolic Ca2+ was not affected by pretreatment with bradykinin. Pretreatment of the cells with either forskolin or phorbol 12-myristate 13-acetate (activators of adenylyl cyclase and protein kinase C, respectively) prior to bradykinin application accelerated the recovery of cytosolic Ca2+ to baseline levels. These data suggest that bradykinin receptors are functional in Ca2+ signaling in HSC-3 cells and may therefore represent a future target in treatment strategies for human oral squamous cell carcinoma.

Chios gum mastic (CGM) is a resin produced from the stem and leaves of Pistiacia lentiscus L var chia, a plant which grows only on Chios Island in Greece. CGM has been used for many centuries as a dietary supplement and folk medicine for stomach and duodenal ulcers in many Mediterranean countries and is known also to induce cell cycle arrest and apoptosis in some cancer cells. In this study, we further investigated the induction and mechanisms underlying the apoptotic response to CGM treatment in the SCC25 human tongue squamous cell carcinoma cell line. The viability of SCC25 cells, human normal keratinocytes (HaCaT cells) and human gingival fibroblasts (HGF-1 cells), and the growth inhibition of SCC25 cells were assessed by MTT assay and clonogenic assay, respectively. Staining with Hoechst and hemacolor dyes and TUNEL assays were employed to detect SCC25 cells undergoing apoptosis. SCC25 cells were treated with CGM, and this was followed by western blotting, immunocytochemistry, confocal microscopy, FACScan flow cytometry, MMP activity and proteasome activity analyses. CGM treatment of SCC25 cells was found to result in a time- and dosedependent decrease in cell viability, a dose-dependent inhibition of cell growth, and apoptotic cell death. Interestingly, CGM showed a remarkable level of cytotoxicity in SCC25 cells but not in normal cells. Tested SCC25 cells also showed several lines of apoptotic manifestation. Taken together, our present findings demonstrate that CGM strongly inhibits cell proliferation by modulating the expression of G1 cell cycle-related proteins and induces apoptosis via the proteasome, mitochondria and caspase cascades in SCC25 cells.

Amino acid transporters are essential for the growth and proliferation in all living cells. Among the amino acid transporters, the system L amino acid transporters are the major nutrient transport system responsible for the Na+-independent transport of neutral amino acids including several essential amino acids. The L-type amino acid transporter 1 (LAT1), an isoform of system L amino acid transporter, is highly expressed in cancer cells to support their continuous growth and proliferation. 2-Aminobicyclo-(2,2,1)-heptane-2-carboxylic acid(BCH) is a model compound for study of amino acid transporter as a system L selective inhibitor. We have examined the effect and mechanism of BCH on cell growth suppression in FaDu human head and neck squamous cell carcinoma. The BCH inhibited the L-leucine transport in a concentration-dependent manner with a IC 50 value of 43.8±4.3μM. The majority of L-leucine uptake is, therefore, mediated by LAT1 in FaDu cells. The growth of FaDu cells was inhibited by BCH in the time- and concentration- dependent manners. The formation of DNA ladder was not observed with BCH treatment in the cells. Furthermore, the proteolytic processing of caspase-3 and caspase-7 in the cells was not detected by BCH treatment. These results suggest that the BCH inhibits the growth of FaDu human head and neck squamous cell carcinoma through the intracellular depletion of neutral amino acids for cell growth without apoptotic processing

Oral squamous carcinoma (OSC) is the most common malignant neoplasm of the oral mucosa. Although the etiology of OSC is not fully understood, accumulated evidences indicate that the activation of proto-oncogenes and the inactivation of tumor suppressor genes underlie the disease development. An OSC cell line, YD-9 was newly established and characterized. However, the mutational analysis of p53 gene was not performed. Thus, in this study, the presence of mutation in the p53 gene was examined by amplification of exon-4 to -8 and subsequent DNA sequencing. Two point mutations were found in exon-4 and -6: A to G, resulting in amino acid change Tyr to Cys in exon-4, and C to G, resulting in amino acid change Gly to Arg in exon-6, respectively. Any mutation was not found in the exon-5, -7 and -8. The presented results would contribute to basic research to understand the biological mechanism of OSC using YD-9 cells.

It is well known that the imbalance between epithelial cell growth and inhibitor factors may cause human epithelial cancer. Over-expression of the epidermal growth factor receptor(EGFR) has been implicated in the development of oral squamous cell carcinoma. ZD1839 inhibits selectively the EGFR tyrosine kinase activity and is clinically used for cancer patients. However the mechanisms by which it exerts its anti-tumor activity remains unclear. This study attempted to determine the mechanisms underlying the effects of ZD1839 on the cellular level and to characterize the effects of ZD1839 with regard to human oral squamous cell carcinoma(OSCC) cell growth. The YD-10B and YD-38 cell lines established from OSCC in the department of Oral Pathology, Yonsei University College of Dentistry and ZD1839(Iressa) were used for this study. The inhibition of cell proliferation induced by ZD1839 was reversible and the lowest dose of ZD1839 that produced statistically significant growth inhibition in YD cell lines were 0.1 μM. The delay in cell cycle progression was induced by 0.1 μM of ZD1839 treatment after 24 hr. This reduction in cell proliferation and cell cycle delay were associated with up-regulation of the cyclin dependent kinase inhibitor(CDKI), P21CIP1/WAF1 and P27KIP1. Reduced expression of cyclin D1 was also observed after treatment with ZD 1839 to YD-38 cells but not to YD-38. The present results suggest that the antiproliferative effects of ZD1839, in vitro was associated with degradation of cyclin D1, which may be used as a possible indicator of a high cell sensitivity to ZD1839.

Amino acid transporters are essential for the growth and proliferation in all living cells. Among the amino acid transporters, the system L amino acid transporters are the major nutrient transport system responsible for the Na+-independent transport of neutral amino acids including several essential amino acids. The L-type amino acid transporter 1 (LAT1) is over-expressed to support cell growth in malignant tumors. The double stranded RNA-mediated RNA interference (RNAi) analysis can be in a wide variety of eukaryotes to induce the sequence-specific inhibition of gene expression. In this study, we examined the effect of LAT1 short interfering RNA (siRNA) on cell growth using siRNA of LAT1 in the KB human oral squamous cell carcinoma. In the RT-PCR analysis and western blot analysis, the siRNA of LAT1 inhibited expressions of LAT1 mRNA and protein. The uptake of [14C]L-leucine was inhibited by siRNA of LAT1. In the MTT assay, the siRNA of LAT1 inhibited the growth of the KB cells in the time-dependent manner, indicating that the growth inhibition of KB cell by the siRNA of LAT1 is induced by the blocking of neutral amino acid transport mediated by LAT1. These results suggest that the transport of neutral amino acids including several essential amino acids into the KB human oral squamous cell carcinoma is mediated mainly by LAT1. Further, the LAT1 would be a new target for the inhibition of cancer cell growth.

This study was conducted to test the anticancer effect of photodynamic therapy using chlorophyll derivative (9-HpbD-a) and 632nm diode laser. Human SNU 1041 cells were seeded into 96 well plate of 104cells/well and cultured for 24 hours. Cells were washed with media containing various concentration of 9-HpbD-a ranging from Oug/ml to 3.75ug/ml. Then 932 nm diode laser was given at various lasering time setting, and at various starting time after ini tial 24 hours of culture. The treated cells were incubated 48 hours and tetrazolium-based colorimetric(M'IT) assay was done to measure the viability of cells For in vivo study, SNU- 1041 cells were xenografted into the back of nude mouse. When the xenografted tumors grew up to 400-600 mm3, the animals were randomly placed into 4 groups: Group 1 (n=20) , PDT group, interstitial injection of 9-HpbD- a (47 ug/kg) followed by irradiation with 3.2 J/c야 of light 6 hours after then i띠 ection; Group II (n=lO) , irradiation with 3.2 J/crrf of light using diode laser; Group III (n=lO), in terstitial injection of 9-HpbD- a only(47 ug/kg); Group IV (n=lO), normal control group. The viability of cells was de creased with increasing lasering time No significant difference of cell viability was noted by variously delayed starting time of lasering. PDT effects were observed in the xenografted nude mouse model Group IV (no 9-HpbD-a, no laser irradiation) was a control group which showed a continuous tumor growth. Group III (9-HpbD-a i띠 ection only) showed no response, Group II (laser irradiation only) sho￦ed 1 complete remission out of 10 (10%) , Group 1 (9-HpbD-a and laser irradiation) showed 13 cpmplete remission out of 20 (65%) , Group 1 showed significant remission rate, comparing to other groups (p<0.05). This study demonstrated anticancer effect of photodynamic therapy using 9-HpbD-a and 632nm diode laser on human squamous cell carcinoma cell line.