[Systematic review and Meta-analysis of efficacy and safety of Yangwei Granules for chronic gastritis].

To systematically evaluate the efficacy and safety of Yangwei Granules combined with conventional Western medicine for chronic gastritis. CNKI, SinoMed, WanFang, VIP, PubMed, Cochrane Library and EMbase database were electronically retrieved to collect randomized controlled trial(RCT) of Yangwei Granules combined with conventional Western medicine for chronic gastritis. Two reviewers independently screened out literatures according to the inclusion and exclusion criteria and extracted data, and evaluated the risk of bias of included studies. Meta-analysis was conducted by using RevMan 5.3 software. A total of 12 RCTs involving 1 164 patients were included. The results of Meta-analysis showed that:(1) The total effective rate of Yangwei Granules combined with conventional Western medicine for chronic gastritis was better than that of conventional Western medicine group, with a statistically significant difference(RR=1.24,95%CI[1.17,1.31],P<0.000 01).(2) Compared with the conventional Western medicine group, the Yangwei Granules combined with conventional Western medicine group was conducive to improving the Hp eradication rate, with a statistically significant difference(RR=1.24,95%CI[1.15,1.34],P<0.000 01).(3) The incidence of adverse reactions in Yangwei Granules combined with conventional Western medicine group was lower than that in the control group, but with no statistically significant diffe-rence(RR=0.83, 95%CI[0.39, 1.79], P=0.64).(4) Compared with the conventional Western medicine group, the Yangwei Granules combined with conventional Western medicine group was beneficial to the reduction of motilin level(MD=-17.31,95%CI[-21.83,-12.79],P<0.000 01) and endothelin level(MD=-6.60,95%CI[-10.07,-3.13],P=0.000 2), while the increase of gastrin level(SMD=0.94,95%CI[0.50,1.38],P=0.003) was related to calcitonin gene the level of peptide(MD=5.82,95%CI[4.25,7.39],P<0.000 01), with statistically significant differences.(5) Compared with conventional Western medicine group, Yangwei Granules combined with conventional Western medicine group could increase PGⅠ(MD=6.40,95%CI[4.26,8.54],P<0.000 01) and PGR(MD=0.89,95%CI[0.71,1.07],P<0.000 01), while decrease PGⅡ(MD=-1.24,95%CI[-2.15,-0.33],P=0.007), with statistically significant differences. Current evidence showed that the clinical efficacy and Hp eradication rate of Yangwei Granules combined with conventional Western medicine in the treatment of chronic gastritis were better than those of the conventional Western medicine group alone, and could effectively improve the level of gastrointestinal hormones, vasoactive peptide and the pepsinogen level in patients with chronic atrophic gastritis, without increasing the incidence of adverse reactions. However, due to the limited quality and quantity of included studies, the above conclusions need to be confirmed by more large-scale and high-quality RCTs.

Increased receptor activator of nuclear factor kappa B ligand expressed on B10 cells in rheumatoid arthritis / 北京大学学报(医学版)

OBJECTIVE@#To detect receptor activator of nuclear factor kappa B ligand (RANKL) expressed on B10 cells in rheumatoid arthritis (RA) and to evaluate the correlation between RANKL-producing B10 cells in RA and clinical features and laboratory parameters, trying to reveal the possible role of B10 cells in the pathogenesis of RA and the potential mechanism of impaired immunosuppressive capacities.@*METHODS@#25 RA patients and 20 healthy volunteers were enrolled. These RA patients did not received treatment with glucocorticoids, disease-modifying anti-rheumatic drug and biologics during the recent half of a year. The levels of RANKL-producing B10 cells were measured by flow cytometry (FCM) and polymerase chain reaction (PCR). The correlation between the frequencies of RANKL-producing B10 cells in RA and clinical data, laboratory parameters were analyzed. The role of tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) in inducing RANKL expression in B10 cells was evaluated by in vitro stimulation assay. Independent samples t test, Pearson and Spearman correlation were used for statistical analysis.@*RESULTS@#B10 cells were capable of producing RANKL at a low level in health controls. The frequencies of RANKL-producing B10 cells were markedly higher in RA patients than in health controls (3.65%±1.59% vs. 2.25%±0.68%, P<0.01). The frequencies of these cells correlated positively with RA tender joint counts, swollen joint counts and disease activity score in 28 joints (DAS28) (r=0.479, P=0.035; r=0.519, P=0.008; r=0.526, P=0.019). However, no correlation was found between these cells and RA patient age, disease duration, or the levels of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF) and anti-citrullinated peptide antibody (ACPA). After in vitro stimulation by TNF-α, but not IL-1β, B10 cells isolated from healthy donors demonstrated fundamentally upregulated expression of RANKL.@*CONCLUSION@#Our studies showed the frequencies of RANKL-producing B10 cells were markedly higher in RA patients, and their frequencies were positively correlated with RA tender joint counts, swollen joint counts and DAS28. These findings suggested that B10 cells might be involved in RA bone destruction.

Effect on prognosis of degenerative medial meniscal tears underwent arthroscopic surgery / 中国内镜杂志

Obejective To evaluate the outcome at a 2 and 5 year follow-up whether combined arthroscopic surgery followed by exercise therapy was superior to the same exercise therapy alone when treating non-traumatic, degenerative medial meniscal tears. Methods Prospective cohort study was used in this study, 96 middle-aged patients with MRI verified degenerative medial meniscus tear and radiographic osteoarthritis grade ≤ 1 participated in the study. Radiographic examination was done before randomization and after 5 years. The patients were randomly assigned to either arthroscopic treatment followed by exercise therapy for 2 months or to the same exercise therapy alone. At the start of the study and at the follow-ups at 24 and 60 months the patients answered three questionnaires KOOS, Lysholm Knee Scoring Scale and Tegner Activity Scale and made pain ratings on the Visual Analogue Scale (VAS). Results Both groups showed highly significant clinical improvements from baseline to the follow-ups at 24 and 60 months on all subscales of KOOS, Lysholm Knee Scoring Scale and VAS (P = 0.000). No group differences were found at any of the testing occasions. One third of the patients that were treated with exercise therapy alone did not feel better after the treatment but were improved after arthroscopic surgery. According to radiographic findings two patients from each group had a slight progression of their osteoarthritis after 5 years. Conclusion The findings indicate that arthroscopic surgery followed by exercise therapy was not superior to the same exercise therapy alone for this type of patients. Consequently, exercise therapy can be recommended as initial treatment. However, one third of the patients from the exercise group still had disabling knee symptoms after exercise therapy but improved to the same level as the rest of the patients after arthroscopic surgery with partial meniscectomy.

A requirement for bid for induction of apoptosis by photodynamic therapy with a lysosome- but not a mitochondrion-targeted photosensitizer.

Photodynamic therapy (PDT) with lysosome-targeted photosensitizers induces the intrinsic pathway of apoptosis via the cleavage and activation of the BH3-only protein Bid by proteolytic enzymes released from photodisrupted lysosomes. To investigate the role of Bid in apoptosis induction and the role of damaged lysosomes on cell killing by lysosome-targeted PDT, we compared the responses of wild type and Bid-knock-out murine embryonic fibroblasts toward a mitochondrion/endoplasmic reticulum-binding photosensitizer, Pc 4, and a lysosome-targeted sensitizer, Pc 181. Whereas apoptosis and overall cell killing were induced equally well by Pc 4-PDT in both cell lines, Bid(-/-) cells were relatively resistant to induction of apoptosis and to overall killing following PDT with Pc 181, particularly at low PDT doses. Thus, Bid is critical for the induction of apoptosis caused by PDT with the lysosome-specific sensitizers, but dispensable for PDT targeted to other membranes.

Atg7 deficiency increases resistance of MCF-7 human breast cancer cells to photodynamic therapy.

Photodynamic therapy (PDT) uses a photosensitizer, light and oxygen to produce extensive oxidative damage to organelles housing the photosensitizer. Although PDT is an efficient trigger of apoptosis, it also induces autophagy in many kinds of cells. Autophagy can serve as both a cell survival and a cell death mechanism. Our previous study indicates that autophagy contributes to cell death after PDT, especially in apoptosis-deficient cells. Here, we provide further evidence to support the role of autophagy in cell killing after PDT. Autophagy was blocked by knockdown of one essential factor, LC3 or Atg7, in MCF-7 cells. The cells were exposed to a range of doses of PDT sensitized by the phthalocyanine Pc 4; steps in autophagy were monitored by western blotting for LC3-II and by fluorescence microscopy for the uptake of monodansylcadaverine or for the distribution of transfected GFP-LC3; and overall cell death was monitored by MTT assay and by clonogenic assay. We find that blocking autophagy increased the survival of MCF-7 cells after PDT and increased the shoulder on the dose-response curve. In response to Pc 4-PDT, Atg7-deficient MCF-7 cells remained capable of robust accumulation of LC3-II, but were defective in comparison to Atg7(+) cells in the formation of autophagosomes. We conclude that apoptosis-deficient cells rely on autophagy for cell death after Pc 4-PDT and that the strong activation of LC3 maturation in response to PDT could occur even in cells with limited or no Atg7 expression.

Structural factors and mechanisms underlying the improved photodynamic cell killing with silicon phthalocyanine photosensitizers directed to lysosomes versus mitochondria.

The phthalocyanine photosensitizer Pc 4 has been shown to bind preferentially to mitochondrial and endoplasmic reticulum membranes. Upon photoirradiation of Pc 4-loaded cells, membrane components, especially Bcl-2, are photodamaged and apoptosis, as indicated by activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase, is triggered. A series of analogs of Pc 4 were synthesized, and the results demonstrate that Pcs with the aminopropylsiloxy ligand of Pc 4 or a similar one on one side of the Pc ring and a second large axial ligand on the other side of the ring have unexpected properties, including enhanced cell uptake, greater monomerization resulting in greater intracellular fluorescence and three-fold higher affinity constants for liposomes. The hydroxyl-bearing axial ligands tend to reduce aggregation of the Pc and direct it to lysosomes, resulting in four to six times more killing of cells, as defined by loss of clonogenicity, than with Pc 4. Whereas Pc 4-PDT photodamages Bcl-2 and Bcl-xL, Pc 181-PDT causes much less photodamage to Bcl-2 over the same dose-response range relative to cell killing, with earlier cleavage of Bid and slower caspase-3-dependent apoptosis. Therefore, within this series of photosensitizers, these hydroxyl-bearing axial ligands are less aggregated than is Pc 4, tend to localize to lysosomes and are more effective in overall cell killing than is Pc 4, but induce apoptosis more slowly and by a modified pathway.

Choline Molecular Imaging with Small-animal PET for Monitoring Tumor Cellular Response to Photodynamic Therapy of Cancer.

We are developing and evaluating choline molecular imaging with positron emission tomography (PET) for monitoring tumor response to photodynamic therapy (PDT) in animal models. Human prostate cancer (PC-3) was studied in athymic nude mice. A second-generation photosensitizer Pc 4 was used for PDT in tumor-bearing mice. MicroPET images with (11)C-choline were acquired before PDT and 48 h after PDT. Time-activity curves of (11)C-choline uptake were analyzed before and after PDT. For treated tumors, normalized choline uptake decreased significantly 48 h after PDT, compared to the same tumors pre-PDT (p < 0.001). However, for the control tumors, normalized choline uptake increased significantly (p < 0.001). PET imaging with (11)C-choline is sensitive to detect early tumor response to PDT in the animal model of human prostate cancer.

Apoptosis mechanisms related to the increased sensitivity of Jurkat T-cells vs A431 epidermoid cells to photodynamic therapy with the phthalocyanine Pc 4.

To examine the clinical applicability of Pc 4, a promising second-generation photosensitizer, for the photodynamic treatment of lymphocyte-mediated skin diseases, we studied the A431 and Jurkat cell lines, commonly used as surrogates for human keratinocyte-derived carcinomas and lymphocytes, respectively. As revealed by ethyl acetate extraction and absorption spectrophotometry, uptake of Pc 4 into the two cell lines was linear with Pc 4 concentration and similar on a per cell basis but greater in Jurkat cells on a per mass basis. Flow cytometry showed that uptake was linear at low doses; variations in the dose-response for uptake measured by fluorescence supported differential aggregation of Pc 4 in the two cell types. As detected by confocal microscopy, Pc 4 localized to mitochondria and endoplasmic reticulum in both cell lines. Jurkat cells were much more sensitive to the lethal effects of phthalocyanine photodynamic therapy (Pc 4-PDT) than were A431 cells, as measured by a tetrazolium dye reduction assay, and more readily underwent morphological apoptosis. In a search for molecular factors to explain the greater photosensitivity of Jurkat cells, the fate of important Bcl-2 family members was monitored. Jurkat cells were more sensitive to the induction of immediate photodamage to Bcl-2, but the difference was insufficient to account fully for their greater sensitivity. The antiapoptotic protein Mcl-1 was extensively cleaved in a dose- and caspase-dependent manner in Jurkat, but not in A431, cells exposed to Pc 4-PDT. Thus, the greater killing by Pc 4-PDT in Jurkat compared with A431 cells correlated with greater Bcl-2 photodamage and more strongly to the more extensive Mcl-1 degradation. Pc 4-PDT may offer therapeutic advantages in targeting inflammatory cells over normal keratinocytes in the treatment of T-cell-mediated skin diseases, such as cutaneous lymphomas, dermatitis, lichenoid tissue reactions and psoriasis, and it will be instructive to evaluate the role of Bcl-2 family proteins, especially Mcl-1, in the therapeutic response.

Protection by Bcl-2 against apoptotic but not autophagic cell death after photodynamic therapy.

Photodynamic therapy (PDT) induces apoptosis in many cell types. Recent reports identified autophagy as an alternative cell-death process following PDT. Here we investigated the occurrence of autophagy after PDT with the photosensitizer Pc 4 in human cancer cells that are deficient in the pro-apoptotic factor Bax (human prostate cancer DU145) or the apoptosis mediator caspase-3 (human breast cancer MCF-7v) and in apoptosis-competent cells (MCF-7c3 stably overexpressing human pro-caspase-3 and Chinese hamster ovary CHO 5A100). Further, each cell line was also studied with and without stably overexpressed Bcl-2. By electron microscopy and immunoblot analysis, autophagy was observed in all cells studied, whether or not they were capable of typical apoptosis or overexpressed Bcl-2. Bcl-2 overexpression protected against PDT-induced apoptosis and loss of clonogenicity in apoptosis-competent cells (MCF-7c3 and CHO); however, it did not protect against the development of autophagy or against loss of clonogenicity in apoptosis-deficient cells (MCF-7v and DU145). The results show that autophagy may be the dominant cell death pathway following PDT in cells that are incapable of undergoing normal apoptosis. In such cells, Bcl-2 does not protect against autophagic death.

The death of human cancer cells following photodynamic therapy: apoptosis competence is necessary for Bcl-2 protection but not for induction of autophagy.

Photodynamic therapy (PDT) is an efficient inducer of apoptosis in many types of cells, except in cells deficient in one or more of the factors that mediate apoptosis. Recent reports have identified autophagy as a potential alternative cell death process following PDT. Here we investigated the occurrence of autophagy after PDT with the photosensitizer Pc 4 in human cancer cells that are deficient in the pro-apoptotic factor Bax (human prostate cancer DU145 cells) or the apoptosis mediator caspase-3 (human breast cancer MCF-7v cells) and in apoptosis-competent cells (MCF-7c3 cells that stably overexpress human pro-caspase-3 and Chinese hamster ovary CHO 5A100 cells). Further, each of the cell lines was also studied with and without stably overexpressed Bcl-2. Autophagy was identified by electron microscopic observation of the presence of double-membrane-delineated autophagosomal vesicles in the cytosol and by immunoblot observation of the Pc 4-PDT dose- and time-dependent increase in the level of LC3-II, a component of the autophagosomal membrane. Autophagy was observed in all of the cell lines studied, whether or not they were capable of typical apoptosis and whether or not they overexpressed Bcl-2. The presence of stably overexpressed Bcl-2 in the cells protected against PDT-induced apoptosis and loss of clonogenicity in apoptosis-competent cells (MCF-7c3 and CHO 5A100 cells). In contrast, Bcl-2 overexpression did not protect against the development of autophagy in any of the cell lines or against loss of clonogenicity in apoptosis-deficient cells (MCF-7v and DU145 cells). Furthermore, 3-methyladenine and wortmannin, inhibitors of autophagy, provided greater protection against loss of viability to apoptosis-deficient than to apoptosis-competent cells. The results show that autophagy occurs during cell death following PDT in human cancer cells competent or not for normal apoptosis. Only the apoptosis-competent cells are protected by Bcl-2 against cell death.

Differential responses of Mcl-1 in photosensitized epithelial vs lymphoid-derived human cancer cells.

The antiapoptotic Bcl-2-family proteins, Bcl-2 and Bcl-xL, are recognized phototargets of photodynamic therapy (PDT) with the mitochondrion-targeting phthalocyanine photosensitizer Pc 4. In the present study, we found that myeloid cell leukemia 1 (Mcl-1), another antiapoptotic member of the Bcl-2 family, was not photodamaged in Pc 4-PDT-treated human carcinoma cells MCF-7c3, MDA-MB468, DU145, and A431, although Mcl-1 turnover was observed after exposure of HeLa or MCF-7c3 cells to a supralethal dose of UVC. In contrast, when human lymphoma U937 and Jurkat cells were treated with Pc 4-PDT, staurosporine (STS) or UVC, Mcl-1 was cleaved to generate a 28-kDa fragment over a 2-4 h period. The cleavage of Mcl-1 was accompanied by the activation of caspases-3, -9, and -8. The broad-specificity caspase inhibitor z-VAD-fmk completely blocked Mcl-1 cleavage induced by PDT, STS or UVC, providing evidence for Mcl-1 as a substrate for caspases. Western blot analysis localized Mcl-1 to mitochondria, ER, and cytosol of both MCF-7c3 and U937 cells, suggesting that Mcl-1 protein, unlike Bcl-2 and Bcl-xL, is not a target for Pc 4-PDT, probably due to its localization to sites removed from those of Pc 4 binding. The 28-kDa cleaved fragment of Mcl-1, which has proapoptotic activity, was produced in PDT-treated lymphoid-derived cells, but not in cells of epithelial origin, suggesting that PDT-induced rapid and extensive apoptosis in lymphoma cells may result in part from the sensitivity of their Mcl-1 to caspase cleavage, removing an important negative control on apoptosis.

Photodamage to multiple Bcl-xL isoforms by photodynamic therapy with the phthalocyanine photosensitizer Pc 4.

The antiapoptotic oncoprotein Bcl-2 is now a recognized phototarget of photodynamic therapy (PDT) with the phthalocyanine Pc 4 and with other mitochondrion-targeting photosensitizers. Photodamage, observed on Western blots as the loss of the native 26-kDa Bcl-2 protein, is PDT dose dependent and occurs in multiple cell lines, in the cold, and immediately upon photoirradiation. In our initial study, no photochemical damage was observed to Bcl-xL, in spite of its similarity in size, sequence, location and function to Bcl-2. The original study used a commercial anti-Bcl-xS/L antibody. We have revisited this issue by examining Western blots developed using one of three epitope-specific anti-Bcl-xL antibodies from commercial sources, a polyclonal antibody generated to the entire protein, as well as the antibody used previously. All five Bcl-xL antibodies recognized bacterially expressed Bcl-xL, but not Bcl-2, whereas an anti-Bcl-2 antibody recognized Bcl-2 and not Bcl-xL. All five Bcl-xL antibodies recognized at least one protein migrating at approximately 30 kDa; two of the antibodies recognized an additional band, migrating at approximately 33 or approximately 24 kDa. We now observe Pc 4-PDT-induced photodamage to all Bcl-xL-related proteins, except the 33-kDa species, in several human cancer cell lines. The results indicate that, in addition to the expected quantitative differences that may reflect exposure of individual epitopes, the antibodies also detect proteins of different apparent molecular weights that may be distinct isoforms or post-translationally modified forms of Bcl-xL. No evidence for PDT-induced phosphorylation or degradation was observed. Bcl-xL localized to mitochondria was considerably more sensitive to photodamage than was Bcl-xL in the cytosol, indicating that as previously found for Bcl-2, Bcl-xL must be membrane localized to be photosensitive.

Staurosporine-induced death of MCF-7 human breast cancer cells: a distinction between caspase-3-dependent steps of apoptosis and the critical lethal lesions.

To test the role of caspase 3 in apoptosis and in overall cell lethality caused by the protein kinase inhibitor staurosporine, we compared the responses of MCF-7c3 cells that express a stably transfected CASP-3 gene to parental MCF-7:WS8 cells transfected with vector alone and lacking procaspase-3 (MCF-7v). Cells were exposed to increasing doses (0.15-1 microM) of staurosporine for periods up to 19 h. Apoptosis was efficiently induced in MCF-7c3 cells, as demonstrated by cytochrome c release, processing of procaspase-3, procaspase-8, and Bid, increase in caspase-3-like DEVDase activity, cleavage of the enzyme poly(ADP-ribose) polymerase, DNA fragmentation, changes in nuclear morphology, and TUNEL assay and flow cytometry. For all of these measures except cytochrome c release, little or no activity was detected in MCF-7v cells, confirming that caspase-3 is essential for efficient induction of apoptosis by staurosporine, but not for mitochondrial steps that occur earlier in the pathway. MCF-7c3 cells were more sensitive to staurosporine than MCF-7v cells when assayed for loss of viability by reduction of a tetrazolium dye. However, the two cell lines were equally sensitive to killing by staurosporine when evaluated by a clonogenic assay. A similar distinction between apoptosis and loss of clonogenicity was observed for the cancer chemotherapeutic agent VP-16. These results support our previous conclusions with photodynamic therapy: (a) assessing overall reproductive death of cancer cells requires a proliferation-based assay, such as clonogenicity; and (b) the critical staurosporine-induced lethal event is independent of those mediated by caspase-3.

Promotion of photodynamic therapy-induced apoptosis by the mitochondrial protein Smac/DIABLO: dependence on Bax.

Photodynamic therapy (PDT) using the second-generation photosensitizer phthalocyanine (Pc) 4 causes mitochondrial damage and induces apoptosis through the release of cytochrome c to the cytosol. Another protein of the mitochondrial intermembrane space, Smac/DIABLO (second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI), is also released to the cytosol in response to apoptotic stimuli and promotes caspase activation by binding IAP. To investigate the possible role of Smac/DIABLO in apoptosis induced by Pc 4-PDT, we transfected Smac/DIABLO (tagged at its C-terminus with green fluorescent protein [GFP]) into MCF-7c3 cells (human breast cancer MCF-7 cells stably transfected with procaspase-3) and DU-145 cells (human prostate cancer cells that express no Bax because of a frameshift insertion mutation). Confocal microscopy showed that recombinant Smac/DIABLO, like cytochrome c, localized to mitochondria and colocalized with MitoTracker Red. Three hours after exposure of MCF-7c3 cells to PDT (200 nM Pc 4 and 150 mJ/cm2 red light), Smac/DIABLO-GFP, as well as cytochrome c, was found largely in the cytosol. In contrast, for DU-145 cells, both Smac/DIABLO-GFP and cytochrome c remained in the mitochondria after PDT. By staining with Hoechst 33,342, typical apoptotic nuclei were observed in MCF-7c3 cells, but not in DU-145 cells, after Pc 4-PDT. These results suggest that the release of Smac/DIABLO from mitochondria may be regulated by a Bax-mediated mechanism and that Smac/DIABLO may cooperate with the cytochrome c-dependent apoptosis pathway. In addition, in MCF-7c3 cells transfected by Smac/DIABLO-GFP, apoptosis induced by Pc 4-PDT was greater than in cells transfected with the GFP vector alone or in untransfected cells, as determined by flow cytometry. Thus, Smac/DIABLO promotes apoptosis after Pc 4-PDT in a Bax-dependent manner and may facilitate the passage of PDT-treated cells through the late steps of apoptosis.

Photodynamic therapy of human breast cancer xenografts lacking caspase-3.

The human breast cancer cell line MCF-7 is deficient in procaspase-3 and in caspase-3-dependent steps in apoptosis due to deletion of the CASP-3 gene. We previously found that the cells transfected with empty vector (MCF-7v cells) were considerably less sensitive to photodynamic treatment in vitro with the phthalocyanine photosensitizer Pc 4 than were the cells stably transfected with human procaspase-3 cDNA (MCF-7c3 cells); however, overall cell killing, as determined by a clonogenic assay, was not affected by the presence of procaspase-3. The present study was undertaken to determine whether photodynamic therapy (PDT) in vivo was dependent on the ability of the cells to carry out the late steps in apoptosis that are catalyzed by this caspase. Xenografts of MCF-7 cells and the isogenic-derived MCF-7v and MCF-7c3 cells were generated in female athymic nude mice implanted with an estrogen pellet. MCF-7c3 xenografts, but not those of the other two lines, continued to express procaspase-3, as revealed by Western blots of proteins from the cells and the xenografts. When the xenografts reached 50-120 mm(3), some were treated with PDT (1mg/kg Pc 4 i.v. followed 48 h later by 150 J/cm(2) light at 672 nm and 150 mW/cm(2)), while others served as controls (no treatment, light alone, or Pc 4 alone). All Pc 4-PDT-treated tumors and none of the controls exhibited either complete or strong partial responses, and complete responses were durable for the entire observation period of 16 days. The responses were not dependent upon the presence of procaspase-3 in the xenografts. The results indicate that the rapid response of Pc 4-PDT-treated tumors in vivo is not due to their ability to carry out the major caspase-3-mediated late steps in apoptosis.