Apoptosis induced by cryo-injury in human colorectal cancer cells is associated with mitochondrial dysfunction

Garcinol modulates tyrosine phosphorylation of FAK and subsequently induces apoptosis through down-regulation of Src, ERK, and Akt survival signaling in human colon cancer cells

Garcinol, from the fruit rind of Garcinia indica and other species, has been reported to suppress colonic aberrant crypt foci (ACF) formation in rats. In this study, we investigate the beneficial effects of tumor prevention by garcinol on the human colorectal cancer cell line, HT-29. Focal adhesion kinase (FAK) is the major signaling mediator of integrin-mediated cell-matrix contact-regulated cellular proliferation, migration, and apoptosis in adherent cells. Results of Matrigel analysis show that exposure of HT-29 cells to 10 microM garcinol inhibited cell invasion, and decreased the dose-dependent tyrosine phosphorylation of FAK. We further demonstrate by Western blot analysis that garcinol inhibited activation of the Src, MAPK/ERK, and PI3K/Akt signaling pathways. To investigate whether the loss of integrin-mediated cell-matrix contact can induce apoptosis, we demonstrate that garcinol induced it in HT-29 cells. The apoptotic dose of garcinol (20 microM) changed the ratio of the anti-apoptotic Bcl-2 and proapoptotic BAX proteins within 12 h, which correlated with a release of cytochrome c from the mitochondria to the cytosol, and with PARP cleavage. Additionally, we demonstrate that a decreasing MMP-7 protein level in HT-29 cells results in sensitization to garcinol. Garcinol also significantly inhibited the expression of MMP-7 in IL-1beta-induced HT-29 cells. These results suggest that garcinol reduces cell invasion and survival through the inhibition of FAK's downstream signaling.

Development of a tissue engineered human prostate tumor equivalent for use in the evaluation of cryoablative techniques

The study of the effectiveness of cryotherapy as a curative treatment for prostate cancer has often relied on the use of either in vitro cell culture monolayers or animal models. While the data gleaned from these studies have been valuable, each model has inherent limitations. In order to bridge the gap between in vitro studies and clinical applications, we developed a 3-dimensional, tissue engineered human prostate cancer model to simulate and assess the effects of cryotherapy and adjunctive treatments on cell viability and activation of cell death pathways throughout the thermally variable freeze zone. Human prostate cancer cells (PC3) were seeded into collagen based matrices and cryolesions were generated using an Oncura SeedNet Gold cryosurgical device with 17-gauge cryoprobes. Analyses revealed widespread necrosis diminishing towards the edge of the freeze zone, and a time-dependent wave of apoptosis starting as early as 1 hr post-thaw at low temperatures (< -40 degrees C) and moving toward the periphery (-20 degrees C) as recovery times reached 12 and 24 hr. Distal to the -10 degrees C isotherm, minimal cell death was apparent (< 20%) over controls. The adjunctive use of chemotherapeutic agents in conjunction with cryosurgery displayed a similar induction of cell death cascades, but with the zone of cryodestruction extending approximately 10 to 15 degrees C further into the freeze zone periphery. By providing an extracellular environment and a matrix to minimize innate variables, the tissue engineered model yielded a more in vivo-like, tumor-like environment supportive of a deeper understanding of the specific biological responses of cancer cells/tumors to cryotherapeutic intervention.

Energy ablative techniques for treatment of small renal tumors

PURPOSE OF REVIEW

The success of partial nephrectomy for the treatment of small renal cancers has led to the development of energy ablative technologies, which are less invasive alternatives for performing nephron-sparing surgery. Currently, cryoablation and radiofrequency ablation are the two most reported technologies. Both technologies use very different means to cause cellular injury. Additionally, three newer technologies, high-frequency ultrasound ablation, laser interstitial therapy, and microwave therapy are emerging in the literature.

RECENT FINDINGS

Three- and 4-year data for cryoablation and radiofrequency ablation are now becoming available. On the basis of these studies, it is clear that ablative technologies can be effective treatments for select small renal tumors. It is also evident that both percutaneous and laparoscopic approaches offer minimal morbidity.

SUMMARY

As long-term (5 years and greater) outcome data for ablative technologies accumulate, we are likely to see an increase in clinical reports, including more patients who may be candidates for extirpative surgery. Technology will advance, leading to smaller probes with larger treatment zones, making it possible to treat larger tumors and potentially even tumors in the advanced disease state.

Cryoablation of liver tumours -- a review of mechanisms, techniques and clinical outcome

Several techniques exist for in situ destruction or ablation of liver tumours not eligible for resection. Cryoablation, i.e. the use of low temperatures to induce local tissue necrosis, was among the first of the thermal ablative techniques widely used. The procedures have typically been performed by surgeons during laparotomy, but recently minimally invasive cryoablation has been reported feasible. The present review focuses on mechanisms of tissue destruction, techniques of ablation including procedural monitoring, and clinical outcome following cryoablation of liver tumours. Plausible causes of tumour persistence at the site of ablation, i.e. local treatment failure, are discussed. Shortcomings exist in monitoring of the freezing process and may be a main cause. The evidence for the long-term outcome following liver tumour cryoablation needs to be improved. Cryoablation has been challenged by other techniques of tumour ablation such as radiofrequency ablation. Randomised trials against these modern techniques may define the role of cryoablation in the treatment of liver tumours. With improved imaging technology and patient selection, cryoablation of liver tumours may hold promise for selected patients.

Alpha-chaconine, a potato glycoalkaloid, induces apoptosis of HT-29 human colon cancer cells through caspase-3 activation and inhibition of ERK 1/2 phosphorylation

Although alpha-chaconine, one of the two major potato trisaccharide glycoalkaloids, have shown cytotoxic effects on human cancer cells, the exact mechanism of this action of alpha-chaconine is not completely understood. In this study, we found that alpha-chaconine induced apoptosis of HT-29 cells in a time- and concentration-dependent manner by using flow cytometric analysis. We also found that caspase-3 activity and the active form of caspase-3 were increased 12 h after alpha-chaconine treatment. Caspase inhibitors, N-Ac-DEVD-CHO and Z-VAD-fmk, prevented alpha-chaconine-induced apoptosis, whereas alpha-chaconine-induced apoptosis was potentiated by PD98059, an extracellular signal-regulated kinase (ERK) inhibitor. However, pretreatment of the cells with LY294002 and SB203580, inhibitors of PI3K and p38, respectively, BAPTA-AM, an intracellular Ca(2+) chelator, and antioxidants such as N-acetylcysteine (NAC) and Trolox had no effect on the alpha-chaconine-induced cell death. In addition, phosphorylation of ERK was reduced by the treatment with alpha-chaconine. Moreover, alpha-chaconine-induced caspase-3 activity was further increased by the pretreatment with PD98059. Thus, the results indicate that alpha-chaconine induces apoptosis of HT-29 cells through inhibition of ERK and, in turn, activation of caspase-3.

The effect of antioxidants and a caspase inhibitor on cryopreserved rat hepatocytes

Hepatocyte transplantation and use of bioartificial liver support systems have been suggested as potential therapies for fulminant hepatic failure. Cryopreservation in liquid nitrogen is presently the major method of long-term storage of isolated hepatocytes. However, cryopreservation can result in low cell recovery and reduction in differentiated function. Several possible mechanisms of cell death during cryopreservation have been proposed. The most important mechanisms appear to be oxidative stress and apoptosis. In this study, we isolated fresh rat hepatocytes and cryopreserved them in three media: University of Wisconsin (UW) solution, an antioxidant-containing medium, and medium containing a caspase inhibitor. Viability and function of hepatocytes cryopreserved in these media were examined. Cryopreservation conditions had no effect on hepatocyte viability after thawing. However, after culture we found significant improvements in viability and function in both antioxidant- and caspase inhibitor-treated hepatocytes at 6 and 24 h.

Induction of p21WAF1 expression protects HT29 colon cancer cells from apoptosis induced by cryoinjury

BACKGROUND

Cryotherapy is a method of in situ destruction of tumors by freeze/thaw mechanisms. Cancer cells located in the peripheral zone of the tumor undergoing cryotherapy can die by apoptosis. We hypothesized that p21WAF1 is involved in the mediation of cryotherapy-induced apoptosis.

METHODS

HT29 cells grown on a plate were subjected to -10 degrees C and returned to 37 degrees C for various periods of time. Cells were analyzed by flow cytometry, Western blot, and reverse transcriptase-polymerase chain reaction for determining cell-cycle distribution, p21WAF1 protein expression, and messenger RNA levels, respectively. The p21WAF1 expression in nude mouse tumor xenografts after cryotherapy was examined by immunofluorescence staining. A series of the p21WAF1 promoter cloned into a luciferase reporter vector were transfected into HT29 cells for identifying the response element to cryoinjury. Antisense oligodeoxynucleotide (ODN) was applied to examine the effect of p21WAF1 expression on cryotherapy-induced apoptosis.

RESULTS

Both protein and messenger RNA of p21WAF1 were induced by cryoinjury in cultured cells and tumor xenografts. Deletion analysis of the p21WAF1 promoter revealed that a region from -121 to -95 base pairs was responsible for the activation and that this activation was p53 independent. HT29 cells arrested at the G1 phase after cryoinjury. The cryotherapy-induced apoptotic rate in HT29 cells was increased in the presence of antisense p21WAF1 ODN in comparison to the random ODN.

CONCLUSIONS

Induction of p21WAF1 increases tumor cell survival and may result in recurrences at treated sites after cryotherapy. Combining antisense ODN targeted against p21WAF1 and cryotherapy may improve clinical outcomes in the treatment of colorectal cancer.

Increased ratio of saturated to unsaturated C18 fatty acids in colonic adenocarcinoma: implications for cryotherapy and lipid raft function

Mammalian fatty acid synthase (FASE) overexpression has been shown in a number of human malignancies including colonic adenocarcinoma. Since FASE synthesizes only saturated fatty acids, we hypothesized that cancer cells have a greater proportion of long-chain saturated fatty acids. We studied and found an unequivocal increase in saturated C18 fatty acid (stearic acid) in colonic adenocarcinoma compared to adjacent normal colonic mucosa. The increase is even more striking when measured as a ratio of stearic acid to the unsaturated C18 fatty acids (oleic acid and linoleic acid). This change in fatty acid composition of the cancer cells should significantly alter their physical and biological properties. The increase in relative proportion of saturated fatty acids should make the cancer cells more susceptible to cryodamage and measurement of fatty acid composition of cancer cells may help individualize the temperature for cryotherapy. Also, the lipid alterations may affect the structure and functions of lipid rafts, which may enable the cancer cells to affect signaling mechanisms such as those involved in cell growth and apoptosis. Dietary or therapeutic interventions targeting lipid rafts may thus be an option for cancer treatment.

In vivo cryochemotherapy of a human lung cancer model

Cryotherapy, an efficient technique to destroy tumour cells, is sometimes applied locally as a palliative treatment in lung cancers. It can be performed in combination with chemotherapy. Our aims were to determine in vivo: (1) the effects of cryochemotherapy in a human lung adenocarcinoma, (2) if it presents a benefit compared to the separate treatments and (3) if cryotherapy allows a tumour retention of the drug. Cells from the A549 cell line were xenografted into SCID mice. Tumours were treated by cryotherapy, chemotherapy (injection of Vinorelbine: Navelbine) or both and were studied morphologically at variable time points. Apoptosis was analysed by immunohistochemical staining of cleaved caspase-3 and by TUNEL. Intratumour Navelbine concentration was assessed by high performance liquid chromatography. Necrosis was important 2 h after cryochemotherapy (45% of the tumour surface) and at the later time points. Expression of cleaved caspase-3 was not significantly different from that of untreated tumours, except at the time point of 2 h where it was maximal (58%). Navelbine concentration was more important in tumours treated by chemotherapy than in tumours treated by cryochemotherapy, demonstrating that in our model, the benefit of the association observed 2h after treatment was not due to a concentration-dependent effect.

Effects of vitamin E on the cinnamaldehyde-induced apoptotic mechanism in human PLC/PRF/5 cells

1. Cinnamaldehyde has been shown to be effective in inducing cell apoptosis in a number of human cancer cells. The aim of the present study was to investigate the effect of vitamin E on the apoptotic signalling mechanism induced by cinnamaldehyde in human hepatoma PLC/PRF/5 cells. 2. Using the XTT assay, cinnamaldehyde exhibited a powerful antiproliferative effect on PLC/PRF/5 cells. Apoptosis was elicited when cells were treated with 1 micromol/L cinnamaldehyde, as characterized by the appearance of phosphatidylserine on the outer surface of the plasma membrane. 3. The apoptotic effect induced by cinnamaldehyde could be further supported by the release of cytochrome c, Smac/Diablo and Omi/HtrA2 from mitochondria to the cytosol and activation of caspase 3. Cinnamaldehyde also upregulated the expression of pro-apoptotic protein (Bax) and down-regulated the levels of anti-apoptotic proteins, such as Bcl-2 and the inhibitor of apoptosis protein family (X-linked inhibitor of apoptosis protein (XIAP), cellular inhibitor of apoptosis protein (cIAP)-1 and cIAP-2). 4. Cinnamaldehyde induces the generation of reactive oxygen species (ROS) in cells. Following the pre-incubation of PLC/PRF/5 cells with anti-oxidants, it was found that 100 micromol/L vitamin E significantly diminished the effect of cinnamaldehyde-induced apoptosis, whereas a lesser effect was seen with on 100 micromol/L N-acetyl-L-cysteine. Vitamin E effectively blocked the release of cytochrome c, Smac/Diablo and Omi/HtrA2 from mitochondria to the cytosol in cells treated with cinnamaldehyde. Vitamin E also markedly suppressed caspase 3 activation. The expression of apoptotic inhibitors (XIAP, cIAP-1, cIAP-2) and anti-apoptotic (Bcl-2) and pro-apoptotic (Bax) proteins was affected by vitamin E pretreatment. 5. Taken together, the results suggest that cinnamaldehyde triggers apoptosis possibly through the mitochondrial pathway. Pretreatment with vitamin E markedly prevented cinnamaldehyde-mediated apoptosis, which was associated with the modulation of XIAP, cIAP-1, cIAP-2, Bcl-2 and Bax protein activity.

Cryosurgery--a putative approach to molecular-based optimization

Cryosurgery must be performed in a manner that produces a predictable response in an appropriate volume of tissue. In present-day clinical practice, that goal is not always achieved. Concerns with cryosurgical techniques in cancer therapy focus in part on the incidence of recurrent disease in the treated site, which is commonly approximately 20-40% in metastatic liver tumors, and prostate cancers. Whether the cause of this failure is disease-based or technique related, cryosurgery for cancer commonly needs the support of adjunctive therapy in the form of anti-cancer drugs or radiotherapy to increase the rate of cell death in the peripheral zone of the therapeutic lesion where cell survival is in balance for several days post-treatment. Recent evidence has identified a third mechanism of cell death associated with cryosurgery. This mechanism, apoptosis or gene regulated cell death, is additive with both the direct ice-related cell damage that occurs during the operative freeze-thaw intervals and coagulative necrosis that occurs over days post-treatment. In this manuscript we discuss, through a combination of literature review and new data, the combined roles of these distinct modes of cell death in a prostate and colorectal cancer. Data are presented suggesting that sub-freezing temperatures, when sequentially applied with low dose chemotherapy, may provide improved cancer cell death in the freeze zone periphery. Since the mechanism of action of most common chemotherapeutic agents is to initiate apoptosis in cancer cells, the observation that sub-freezing exposures yields a similar effect provides a possible route toward molecular-based procedural optimization to improve therapeutic outcome.

Induction of antiproliferative effect by diosgenin through activation of p53, release of apoptosis-inducing factor (AIF) and modulation of caspase-3 activity in different human cancer cells

Previously, we demonstrated that a plant steroid, diosgenin, altered cell cycle distribution and induced apoptosis in the human osteosarcoma 1547 cell line. The objective of this study was to investigate if the antiproliferative effect of diosgenin was similar for different human cancer cell lines such as laryngocarcinoma HEp-2 and melanoma M4Beu cells. Moreover, this work essentially focused on the mitochondrial pathway. We found that diosgenin had an important and similar antiproliferative effect on different types of cancer cells. In addition, our new results show that diosgenin-induced apoptosis is caspase-3 dependent with a fall of mitochondrial membrane potential, nuclear localization of AIF and poly (ADP-ribose) polymerase cleavage. Diosgenin treatment also induces p53 activation and cell cycle arrest in the different cell lines studied.

Antihepatoma activity of Physalis angulata and P. peruviana extracts and their effects on apoptosis in human Hep G2 cells

Physalis angulata and P. peruviana are herbs widely used in folk medicine. In this study, the aqueous and ethanol extracts prepared from the whole plant of these species were evaluated for their antihepatoma activity. Using XTT assay, three human hepatoma cells, namely Hep G2, Hep 3B and PLC/PRF/5 were tested. The results showed that ethanol extract of P. peruviana (EEPP) possessed the lowest IC50 value against the Hep G2 cells. Interestingly, all extracts showed no cytotoxic effect on normal mouse liver cells. Treatment with carbonyl cyanide m-chlorophenyl hydrazone, a protonophore, caused a reduction of membrane potential (Deltapsim) by mitochondrial membrane depolarization. At high concentrations, EEPP was shown to induce cell cycle arrest and apoptosis through mitochondrial dysfunction as demonstrated by the following observations: (i) EEPP induced the collapse of Deltapsim and the depletion of glutathione content in a dose dependent manner; (ii) pretreatment with the antioxidant (1.0 microg/ml vitamin E) protected cells from EEPP-induced release of ROS; and (iii) at concentrations 10 to 50 microg/ml, EEPP displayed a dose-dependent accumulation of the Sub-G1 peak (hypoploid) and caused G0/G1-phase arrest. Apoptosis was elicited when the cells were treated with 50 microg/ml EEPP as characterized by the appearance of phosphatidylserine on the outer surface of the plasma membrane. The results conclude that EEPP possesses potent antihepatoma activity and its effect on apoptosis is associated with mitochondrial dysfunction.

Monitoring of apoptosis in intact single cells with photothermal microscope

BACKGROUND

The methods for detection of apoptosis, cannot as a rule be applied to intact single cells and do not allow monitoring of the cell population. The photothermal (PT) method was evaluated for detection and monitoring of apoptosis in single intact cells--lymphocytes and blasts.

METHODS

PT microscopy is based on optical registration of cell response to the thermal impact that is induced in a cell due to absorption of a short laser pulse (532 nm, 10 ns) by cellular hem-proteins. With no pretreatment of cells, optical detection of cellular response with this method may allow monitoring of apoptosis. The PT method was applied for in vitro studies of lymphocytes and K562 blast cells during drug-induced apoptosis. Dexamethasone in 10 microM concentration was used and cell properties were monitored for 6 h.

RESULTS

PT parameters of cells deviated from control after incubation with Dexamethasone. Control measurements with fluorescent microscopy (using the Annexin-V-FLUOS kit) verified the development of apoptosis in drug-treated cells, while there was no development of necrosis. Also necrotic cells had PT properties similar to those of control cells. The PT method allowed the detection of the influence of Dexamethasone at earlier stages (2-hr incubation) than the fluorescent technique (4 h).

CONCLUSIONS

Results obtained confirmed the applicability of PT microscopy for detection and monitoring of apoptosis in single intact cells. The sensitivity of the suggested method may exceed the sensitivity of fluorescent methods.