Regulation of cell cycle transition and induction of apoptosis in HL-60 leukemia cells by lipoic acid: role in cancer prevention and therapy

<p>Abstract</p> <p>Background</p> <p>Lipoic acid (LA), a potent antioxidant, has been used as a dietary supplement to prevent and treat many diseases, including stroke, diabetes, neurodegenerative and hepatic disorders. Recently, potent anti-tumorigenic effects induced by LA were also reported and evident as assayed by suppression of cell proliferation and induction of apoptosis in malignant cells. However, the mechanism by which LA elicits its chemopreventive effects remains unclear.</p> <p>Methods and Results</p> <p>Herein, we investigated whether LA elicits its anti-tumor effects by inducing cell cycle arrest and cell death in human promyelocytic HL-60 cells. The results showed that LA inhibits both cell growth and viability in a time- and dose-dependent manner. Disruption of the G₁/S and G₂/M phases of cell cycle progression accompanied by the induction of apoptosis was also observed following LA treatment. Cell cycle arrest by LA was correlated with dose-dependent down regulation of Rb phosphorylation, likely via suppression of E2F-dependent cell cycle progression with an accompanying inhibition of cyclin E/cdk2 and cyclin B1/cdk1 levels. Evidence supporting the induction of apoptosis by LA was based on the appearance of sub-G₁peak in flow cytometry analysis and the cleavage of poly(ADP-ribose) polymerase (PARP) from its native 112-kDa form to the 89-kDa truncated product in immunoblot assays. Apoptosis elicited by LA was preceded by diminution in the expression of anti-apoptotic protein bcl-2 and increased expression of apoptogenic protein bax, and also the release and translocation of apoptosis inducing factor AIF and cytochrome c from the mitochondria to the nucleus, without altering the subcellular distribution of the caspases.</p> <p>Conclusion</p> <p>This study provides evidence that LA induces multiple cell cycle checkpoint arrest and caspase-independent cell death in HL-60 cells, in support of its efficacious potential as a chemopreventive agent.</p

Induction of cell cycle changes and modulation of apoptogenic/anti-apoptotic and extracellular signaling regulatory protein expression by water extracts of I'm-Yunity™ (PSP)

BACKGROUND: I'm-Yunity™ (PSP) is a mushroom extract derived from deep-layer cultivated mycelia of the patented Cov-1 strain of Coriolus versicolor (CV), which contains as its main bioactive ingredient a family of polysaccharo-peptide with heterogeneous charge properties and molecular sizes. I'm-Yunity™ (PSP) is used as a dietary supplement by cancer patients and by individuals diagnosed with various chronic diseases. Laboratory studies have shown that I'm-Yunity™ (PSP) enhances immune functions and also modulates cellular responses to external challenges. Recently, I'm-Yunity™ (PSP) was also reported to exert potent anti-tumorigenic effects, evident by suppression of cell proliferation and induction of apoptosis in malignant cells. We investigate the mechanisms by which I'm-Yunity™ (PSP) elicits these effects. METHODS: Human leukemia HL-60 and U-937 cells were incubated with increasing doses of aqueous extracts of I'm-Yunity™ (PSP). Control and treated cells were harvested at various times and analyzed for changes in: (1) cell proliferation and viability, (2) cell cycle phase transition, (3) induction of apoptosis, (4) expression of cell cycle, apoptogenic/anti-apoptotic, and extracellular regulatory proteins. RESULTS: Aqueous extracts of I'm-Yunity™ (PSP) inhibited cell proliferation and induced apoptosis in HL-60 and U-937 cells, accompanied by a cell type-dependent disruption of the G(1)/S and G(2)/M phases of cell cycle progression. A more pronounced growth suppression was observed in treated HL-60 cells, which was correlated with time- and dose-dependent down regulation of the retinoblastoma protein Rb, diminution in the expression of anti-apoptotic proteins bcl-2 and survivin, increase in apoptogenic proteins bax and cytochrome c, and cleavage of poly(ADP-ribose) polymerase (PARP) from its native 112-kDa form to the 89-kDa truncated product. Moreover, I'm-Yunity™ (PSP)-treated HL-60 cells also showed a substantial decrease in p65 and to a lesser degree p50 forms of transcription factor NF-κB, which was accompanied by a reduction in the expression of cyclooxygenase 2 (COX2). I'm-Yunity™ (PSP) also elicited an increase in STAT1 (signal transducer and activator of transcription) and correspondingly, decrease in the expression of activated form of ERK (extracellular signal-regulated kinase). CONCLUSION: Aqueous extracts of I'm-Yunity™ (PSP) induces cell cycle arrest and alterations in the expression of apoptogenic/anti-apoptotic and extracellular signaling regulatory proteins in human leukemia cells, the net result being suppression of proliferation and increase in apoptosis. These findings may contribute to the reported clinical and overall health effects of I'm-Yunity™ (PSP)

Phase II trial of fenretinide in advanced renal carcinoma

Purpose : Fenretinide, a synthetic form of retinoid, induced apoptosis even in chemotherapy resistant cell lines. A phase II study was hence conducted to evaluate toxicity and efficacy of fenretinide in metastatic renal cancer. Methods : Eligibility included unresectable or metastatic renal cell carcinoma (RCC), adequate organ function and Zubrod performance status ≦2. Prior immunotherapy and a maximum of one prior chemotherapy regimen were allowed. Fenretinide was administered at a dose of 900 mg/m 2 twice daily orally for 7 days in a 21-day cycle. Toxicity was assessed at the start of each cycle, and response every 2 cycles. Results : Nineteen eligible patients enrolled of which fifteen had visceral/bone metastases. Seventeen patients had prior nephrectomy and 11 had prior immunotherapy. 76 cycles of therapy were delivered. Therapy was very well tolerated with few severe toxicities consisting of thrombosis in 1 individual and grade 3 fatigue, nausea and diarrhea in 1 patient. 5 patients had grade 2 nyctalopia and 3 patients had transient grade 2 visual toxicity. No objective responses were noted. Stable disease was seen in seven of nineteen cases (37%, 90% C.I. 0.21–0.59). Median time to progression was 1.5 months and median duration of stable disease was 5.8 months (90% C.I. 3.0–8.4). Median survival was 10 months. Tumor fenretinide levels were obtained in three patients and were in the lower end of the therapeutic range. Conclusion : Fenretinide was well tolerated but demonstrated minimal activity that was consistent with results of intratumoral drug measurements. Strategies are needed that will increase systemic and tumor levels of fenretinide.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45264/1/10637_2005_Article_5864.pd

Treatment of mediastinitis using an open irrigation and delayed sternal reconstruction with a pectoralis major muscle flap

BACKGROUND: Mediastinitis is a very serious complication after cardiac surgery. To date, the optimal treatment of mediastinitis is still controversial: the "closed wound" procedures and the "open wound" treatments are the two conventional modalities reported in the literature. METHODS: Between January 1995 and December 2000, 20 patients, who had previously been submitted to cardiac surgery, were treated by a modification of the "open wound" treatment strategy for postoperative mediastinitis. All patients were scheduled for 2, 6, and 12-month clinical follow-up. The procedure performed consisted of three major steps: 1) early sternum reopening, followed by phase 2) including irrigation of the wound 3 times daily, and the final step 3) of delayed reconstructive surgery using the pectoralis major myocutaneous advancement flap closure technique. We prospectively analyzed the short- and long-term results of these procedures. RESULTS: The overall duration of hospitalization was 25 +/- 10 days; no patient required intensive care unit permanency. Clinical success was achieved in all 20 cases (100%). No recurrences of local (such as fistulas or abscesses) or systemic infections were noted, and no patient required sternal reopening during follow-up. An optimal cosmetic result was obtained in all patients and only 2 cases had persistent sternal pain regressing at the 6-month follow-up control. CONCLUSIONS: Our data suggest that for patients with severe mediastinitis, this treatment strategy is safe. The clinical and esthetic success rates are high, the recovery time rapid, and the rates of short- and long-term complications very low