[Show abstract][Hide abstract] ABSTRACT: Warburg effect is a dominant phenotype of most cancer cells. Here we show that this phenotype depends on its environment. When cancer cells are under regular culture condition, they show Warburg effect; whereas under lactic acidosis, they show a nonglycolytic phenotype, characterized by a high ratio of oxygen consumption rate over glycolytic rate, negligible lactate production and efficient incorporation of glucose carbon(s) into cellular mass. These two metabolic modes are intimately interrelated, for Warburg effect generates lactic acidosis that promotes a transition to a nonglycolytic mode. This dual metabolic nature confers growth advantage to cancer cells adapting to ever changing microenvironment.
[Show abstract][Hide abstract] ABSTRACT: Targeting cancer via ROS-based mechanism has been proposed as a radical therapeutic approach. Cancer cells exhibit higher endogenous oxidative stress than normal cells and pharmacological ROS insults via either enhancing ROS production or inhibiting ROS-scavenging activity can selectively kill cancer cells. In this study, we randomly chose 4 cancer cell lines and primary colon or rectal cancer cells from 4 patients to test the hypothesis and obtained following paradoxical results: while piperlongumin (PL) and β-phenylethyl isothiocyanate (PEITC), 2 well-defined ROS-based anticancer agents, induced an increase of cellular ROS and killed effectively the tested cells, lactic acidosis (LA), a common tumor environmental factor that plays multifaceted roles in promoting cancer progression, induced a much higher ROS level in the tested cancer cells than PL and PEITC, but spared them; L-buthionine sulfoximine (L-BSO, 20 μM) depleted cellular GSH more effectively and increased higher ROS level than PL or PEITC but permitted progressive growth of the tested cancer cells. No evident dose-response relationship between cellular ROS level and cytotoxicity was observed. If ROS is the effecter, it should obey the fundamental therapeutic principle - the dose-response relationship. This is a major concern.
[Show abstract][Hide abstract] ABSTRACT: Cancer metastasis is a major cause for cancer-related death and inhibiting cancer metastasis is an alternative way to treat cancer. Several lines of reported evidence suggest that NADPH oxidase 4 (NOX4) is a potential target for intervention of cancer metastasis, as the reactive oxygen species (ROS) generated by this enzyme plays important roles in TGF-β signaling, an important inducer of cancer metastasis. Here we show (1) that TGF-β induces ROS production in breast cancer 4T1 cells and enhances cell migration and that the effect of TGF-β depends on NOX4 expression, (2) that knockdown of NOX4 via RNAi significantly decreases the migration ability of 4T1 cells in the presence or absence of TGF-β and significantly attenuates distant metastasis of 4T1 cells to lung and bone, (3) that Schisandrin B (Sch B), a naturally-occurring dibenzocyclooctadiene lignan with very low toxicity, is a novel NOX inhibitor and its IC50 toward NOX4 is 9.3μM, and (4) that Sch B suppresses TGF-β-induced and NOX4-associated ROS production in 4T1 cells and inhibits TGF-β-enhanced cell migration. Similar to NOX4 knockdown observed in this study, Sch B significantly attenuated 4T1 cells distant metastasis to lung and bone in our recently-published study. In line with previous reports, the study suggests that pharmacologically targeting NOX4 may be a potential approach to disrupt cancer metastasis.
[Show abstract][Hide abstract] ABSTRACT: Cancer drug resistance is a major obstacle for the success of chemotherapy. Since most clinical anticancer drugs could induce drug resistance, it is desired to develop candidate drugs that are highly efficacious but incompetent to induce drug resistance. Numerous previous studies have proven that shikonin and its analogs not only are highly tumoricidal but also can bypass drug-transporter and apoptotic defect mediated drug resistance. The purpose of this study is to investigate if or not shikonin is a weak inducer of cancer drug resistance.
Different cell lines (K562, MCF-7, and a MDR cell line K562/Adr), after repeatedly treated with shikonin for 18 months, were assayed for drug resistance and gene expression profiling.
After 18-month treatment, cells only developed a mere 2-fold resistance to shikonin and a marginal resistance to cisplatin and paclitaxel, without cross resistance to shikonin analogs and other anticancer agents. Gene expression profiles demonstrated that cancer cells did strongly respond to shikonin treatment but failed to effectively mobilize drug resistant machineries. Shikonin-induced weak resistance was associated with the up-regulation of βII-tubulin, which physically interacted with shikonin.
Taken together, apart from potent anticancer activity, shikonin and its analogs are weak inducers of cancer drug resistance and can circumvent cancer drug resistance. These merits make shikonin and its analogs potential candidates for cancer therapy with advantages of avoiding induction of drug resistance and bypassing existing drug resistance.
PLoS ONE 01/2013; 8(1):e52706. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mitotic chromosomal instability (CIN) plays important roles in tumor progression, but what causes CIN is incompletely understood. In general, tumor CIN arises from abnormal mitosis, which is caused by either intrinsic or extrinsic factors. While intrinsic factors such as mitotic checkpoint genes have been intensively studied, the impact of tumor microenvironmental factors on tumor CIN is largely unknown. We investigate if glucose deprivation and lactic acidosis - two tumor microenvironmental factors - could induce cancer cell CIN. We show that glucose deprivation with lactic acidosis significantly increases CIN in 4T1, MCF-7 and HCT116 scored by micronuclei, or aneuploidy, or abnormal mitosis, potentially via damaging DNA, up-regulating mitotic checkpoint genes, and/or amplifying centrosome. Of note, the feature of CIN induced by glucose deprivation with lactic acidosis is similar to that of aneuploid human tumors. We conclude that tumor environmental factors glucose deprivation and lactic acidosis can induce tumor CIN and propose that they are potentially responsible for human tumor aneuploidy.
PLoS ONE 01/2013; 8(5):e63054. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To establish serum protein fingerprint model for early diagnosis of pancreatic cancer with surface enhanced laser desorption/ionization time of flight-mass spectrometry (SELDI-TOF-MS) and bioinformatics techniques.
A total of 73 samples were analyzed in this study, including 31 cases of pancreatic cancers, 22 cases of pancreatitis and 20 healthy individuals. Samples were first analyzed by SELDI-TOF-MS and two patterns of differentiation model were constructed with support vector machine arithmetic method.
The pattern 1 model differentiating pancreatic cancer patients from healthy individuals had a specificity and a sensitivity of both 100.0%. The pattern 2 model differentiating pancreatic cancer from pancreatitis had a specificity of 95.5% and a sensitivity of 93.5%.
SELDI-TOF-MS technique combined with bioinformatics can facilitate to identify biomarkers for pancreatic cancer.
Zhejiang da xue xue bao. Yi xue ban = Journal of Zhejiang University. Medical sciences 05/2012; 41(3):289-97.
[Show abstract][Hide abstract] ABSTRACT: Cytosolic free NAD/NADH ratio is fundamentally important in maintaining cellular redox homeostasis but current techniques cannot distinguish between protein-bound and free NAD/NADH. Williamson et al reported a method to estimate this ratio by cytosolic lactate/pyruvate (L/P) based on the principle of chemical equilibrium. Numerous studies used L/P ratio to estimate the cytosolic free NAD/NADH ratio by assuming that the conversion in cells was at near-equilibrium but not verifying how near it was. In addition, it seems accepted that cytosolic free NAD/NADH ratio was a dependent variable responding to the change of L/P ratio. In this study, we show (1) that the change of lactate/glucose (percentage of glucose that converts to lactate by cells) and L/P ratio could measure the status of conversion between pyruvate + NADH and lactate + NAD that tends to or gets away from equilibrium; (2) that cytosolic free NAD/NADH could be accurately estimated by L/P only when the conversion is at or very close to equilibrium otherwise a calculation error by one order of magnitude could be introduced; (3) that cytosolic free NAD/NADH is stable and L/P is highly labile, that the highly labile L/P is crucial to maintain the homeostasis of NAD/NADH; (4) that cytosolic free NAD/NADH is dependent on oxygen levels. Our study resolved the key issues regarding accurate estimation of cytosolic free NAD/NADH ratio and the relationship between NAD/NADH and L/P.
PLoS ONE 01/2012; 7(5):e34525. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Metastasis is the major cause of cancer related death and targeting the process of metastasis has been proposed as a strategy to combat cancer. Therefore, to develop candidate drugs that target the process of metastasis is very important. In the preliminary studies, we found that schisandrin B (Sch B), a naturally-occurring dibenzocyclooctadiene lignan with very low toxicity, could suppress cancer metastasis.
BALB/c mice were inoculated subcutaneously or injected via tail vein with murine breast cancer 4T1 cells. Mice were divided into Sch B-treated and control groups. The primary tumor growth, local invasion, lung and bone metastasis, and survival time were monitored. Tumor biopsies were examined immuno- and histo-pathologically. The inhibitory activity of Sch B on TGF-β induced epithelial-mesenchymal transition (EMT) of 4T1 and primary human breast cancer cells was assayed.
Sch B significantly suppressed the spontaneous lung and bone metastasis of 4T1 cells inoculated s.c. without significant effect on primary tumor growth and significantly extended the survival time of these mice. Sch B did not inhibit lung metastasis of 4T1 cells that were injected via tail vein. Delayed start of treatment with Sch B in mice with pre-existing tumors did not reduce lung metastasis. These results suggested that Sch B acted at the step of local invasion. Histopathological evidences demonstrated that the primary tumors in Sch B group were significantly less locally invasive than control tumors. In vitro assays demonstrated that Sch B could inhibit TGF-β induced EMT of 4T1 cells and of primary human breast cancer cells.
Sch B significantly suppresses the lung and bone metastasis of 4T1 cells via inhibiting EMT, suggesting its potential application in targeting the process of cancer metastasis.
PLoS ONE 01/2012; 7(7):e40480. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Solid tumours are dependent on glucose, but are generally glucose-deprived due to poor vascularization. Nevertheless, cancer cells can generally survive glucose deprivation better than their normal counterparts. Thus, to render cancer cells sensitive to glucose depletion may potentially provide an effective strategy for cancer intervention. We propose that lactic acidosis, a tumour microenvironment factor, may allow cancer cells to develop resistance to glucose deprivation-induced death, and that disruption of lactic acidosis may resume cancer cells' sensitivity to glucose depletion. Lactic acidosis, lactosis, or acidosis was generated by adding pure lactic acid, sodium lactate, or HCl to the culture medium. Cell death, cell cycle, autophagy, apoptosis, and gene expression profiling of the surviving cancer cells under glucose deprivation with lactic acidosis were determined. Under glucose deprivation without lactic acidosis, 90% of 4T1 cancer cells died within a single day; in a sharp contrast, under lactic acidosis, 90% of 4T1 cells died in a period of 10 days, with viable cells identified even 65 days after glucose was depleted. Upon glucose restoration, surviving cells resumed proliferation. Lactic acidosis also significantly extended survival of other cancer cells under glucose deprivation. G1/G0 arrest, autophagy induction, and apoptosis inhibition were tightly associated with lactic acidosis-mediated resistance to glucose deprivation. Lactosis alone had no effect on cell survival under glucose deprivation; acidosis alone can prolong cell survival time but is not as potent as lactic acidosis. Thus, the ability of cancer cells to resist glucose deprivation-induced cell death is conferred, at least in part, by lactic acidosis, and we envision that disrupting the lactic acidosis may resume the sensitivity of cancer cells to glucose deprivation.
The Journal of Pathology 12/2011; 227(2):189-99. · 7.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pyruvate kinase M2 (PKM2) is a rate-limiting enzyme of aerobic glycolysis in cancer cells and plays important roles in cancer metabolism and growth. Here we show that vitamin K(3) and K(5) (VK(3) and VK(5)) are relatively specific PKM2 inhibitors. VK(3) and VK(5) showed a significantly stronger potency to inhibit PKM2 than to inhibit PKM1 and PKL, 2 other isoforms of PK dominantly expressed in most adult tissues and liver. This study combined with previous reports supports that VK(3) and VK(5) have potential as adjuvant for cancer chemotherapy.
Cancer letters 11/2011; 316(2):204-10. · 5.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To mitigate the cardiotoxicity of anthracycline antibiotics without compromising their anticancer activities is still an issue to be solved. We previously demonstrated that schisandrin B (Sch B) could protect against doxorubicin (Dox)-induced acute cardiotoxicity via enhancing cardiomyocytic glutathione redox cycling that could attenuate oxidative stress generated from Dox. In this study, we attempted to prove if Sch B could also protect against Dox-induced chronic cardiotoxicity, a more clinically relevant issue, without compromising its anticancer activity.
Rat was given intragastrically either vehicle or Sch B (50 mg/kg) two hours prior to i.p. Dox (2.5 mg/kg) weekly over a 5-week period with a cumulative dose of Dox 12.5 mg/kg. At the 6th and 12th week after last dosing, rats were subjected to cardiac function measurement, and left ventricles were processed for histological and ultrastructural examination. Dox anticancer activity enhanced by Sch B was evaluated by growth inhibition of 4T1, a breast cancer cell line, and S180, a sarcoma cell line, in vitro and in vivo.
Pretreatment with Sch B significantly attenuated Dox-induced loss of cardiac function and damage of cardiomyocytic structure. Sch B substantially enhanced Dox cytotoxicities toward S180 in vitro and in vivo in mice, and increased Dox cytotoxcity against 4T1 in vitro. Although we did not observe this enhancement against the implanted 4T1 primary tumor, the spontaneous metastasis to lung was significantly reduced in combined treatment group than Dox alone group.
Sch B is capable of protecting Dox-induced chronic cardiotoxicity and enhancing its anticancer activity. To the best of our knowledge, Sch B is the only molecule ever proved to function as a cardioprotective agent as well as a chemotherapeutic sensitizer, which is potentially applicable for cancer treatment.
PLoS ONE 01/2011; 6(12):e28335. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Early diagnosis of nasopharyngeal carcinoma (NPC) is difficult due to the insufficient specificity of the conventional examination method. This study was to investigate potential and consistent biomarkers for NPC, particularly for early detection of NPC.
A proteomic pattern was identified in a training set (134 NPC patients and 73 control individuals) using the surface-enhanced laser desorption and ionization-mass spectrometry (SELDI-MS), and used to screen the test set (44 NPC patients and 25 control individuals) to determine the screening accuracy. To confirm the accuracy, it was used to test another group of 52 NPC patients and 32 healthy individuals at 6 months later.
Eight proteomic biomarkers with top-scored peak mass/charge ratios (m/z) of 8605 Da, 5320 Da, 5355 Da, 5380 Da, 5336 Da, 2791 Da, 7154 Da, and 9366 Da were selected as the potential biomarkers of NPC with a sensitivity of 90.9% (40/44) and a specificity of 92.0% (23/25). The performance was better than the current diagnostic method by using the Epstein-Barr virus (EBV) capsid antigen IgA antibodies (VCA/IgA). Similar sensitivity (88.5%) and specificity (90.6%) were achieved in another group of 84 samples.
SELDI-MS profiling might be a potential tool to identify patients with NPC, particularly at early clinical stages.
[Show abstract][Hide abstract] ABSTRACT: Eleven shikonin glycosides were synthesized and evaluated for their antitumor activity in vitro. Some of them were found to exhibit cytotoxic activities against both drug sensitive cell lines (K562, MCF-7 and HL60) and their drug resistant cell sublines (K562/ADR, MCF-7/ADR and HL60/ADR).
European Journal of Medicinal Chemistry 07/2010; 45(7):2713-8. · 3.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Degterev et al. previously demonstrated that death receptor mediated apoptosis could be diverted to necroptosis when apoptosis signaling was blocked, suggesting that necroptosis may function as a backup mechanism to insure the elimination of damaged cells under certain conditions when apoptosis was inhibited. Here, we show that shikonin-induced necroptosis can be reverted to apoptosis in the presence of necrostatin-1 (Nec-1), a specific necroptosis inhibitor and that the death mode switch is at least partially due to the conversion from mitochondrial inner membrane permeability to mitochondrial outer membrane permeability, which is associated with Bax translocation. The data combined with the previous reports support a notion that apoptosis and necroptosis may function as reciprocal backup mechanisms of cellular demise. To the best of our knowledge, this is the first study to document a conversion from necroptosis to apoptosis.
[Show abstract][Hide abstract] ABSTRACT: We previously reported that shikonin could circumvent drug resistance mediated by P-gp, Bcl-2 and Bcl-xL, by induction of necroptosis. Here, we show that the naturally-occurring shikonin analogues (deoxyshikonin, acetylshikonin, isobutyrylshikonin, beta,beta-dimethylacrylshikonin, isovalerylshikonin, alpha-methyl-n-butylshikonin) could bypass drug resistance mediated by not only P-gp, Bcl-2, and Bcl-xL, but also two additional important drug-resistant factors MRP1 and BCRP1, by induction of necroptosis. The results strengthen the previous findings that necroptotic induction could circumvent a broad spectrum of cancer drug resistance.
Cancer letters 12/2008; 274(2):233-42. · 5.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cancer drug resistance is a complex, dynamic, and "elusive" system rather than merely a matter of some drug-resistant factors. Current pharmacological approaches aim to restore the efficacy of the standard chemotherapy against drug-resistant cancers via reactivating apoptosis and inhibiting drug transporters, simply because the current available anticancer drugs mostly induce apoptosis and many of them are the substrates/inducers of the drug transporters. However, since there are so many different types of defects in apoptotic pathways as well as numerous drug transporters, which could simultaneously contribute to cancer drug resistance, to succeed in the approach is theoretically possible but practically extremely difficult. To circumvent cancer drug resistance is an alternative choice. Since there are multiple death pathways with molecular mechanisms distinct from each other, we previously proposed that the barriers set up in cancer cells to avoid one pathway were not problems for another. Thus, no matter how dynamic, complex, and "elusive" the resistance occurs along one death pathway (e.g., apoptosis), the resistance would be sequestered within this pathway, and would not affect another death pathway with mechanisms distinct from the former, and vice versa, e.g., apoptotic resistant cancers can be sensitive to an induction of a nonapoptotic death. Indeed, we recently demonstrated that the cancer cells resistant to apoptotic inducers such as anthracycline antibiotics, vinca alkaloids, epipodophylotoxins, were sensitive to necroptotic inducers such as shikonin. Therefore, to bypass cancer drug resistance is principally achievable by simultaneously activating multiple death pathways using combined classes of death inducers (apoptosis, autophagy, necroptosis, etc.). Although each class of death inducers has its own action window and limit in killing cancer cells, a rationalized combination of several classes of death inducers that compliment each other would maximize their efficacy while simultaneously minimizing their weakness. Such "mixed bullets" would probably achieve a good therapeutic efficacy by bypassing cancer drug resistance.
Cancer Letters 03/2008; 259(2):127-37. · 5.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Phenylobacterium zucineum is a recently identified facultative intracellular species isolated from the human leukemia cell line K562. Unlike the known intracellular pathogens, P. zucineum maintains a stable association with its host cell without affecting the growth and morphology of the latter.
Here, we report the whole genome sequence of the type strain HLK1T. The genome consists of a circular chromosome (3,996,255 bp) and a circular plasmid (382,976 bp). It encodes 3,861 putative proteins, 42 tRNAs, and a 16S-23S-5S rRNA operon. Comparative genomic analysis revealed that it is phylogenetically closest to Caulobacter crescentus, a model species for cell cycle research. Notably, P. zucineum has a gene that is strikingly similar, both structurally and functionally, to the cell cycle master regulator CtrA of C. crescentus, and most of the genes directly regulated by CtrA in the latter have orthologs in the former.
This work presents the first complete bacterial genome in the genus Phenylobacterium. Comparative genomic analysis indicated that the CtrA regulon is well conserved between C. crescentus and P. zucineum.
[Show abstract][Hide abstract] ABSTRACT: The dose-cumulative cardiotoxicities and the emerging cancerous apoptotic/drug resistance are two major obstacles limiting the efficacy of anthracycline antibiotics, notably doxorubicin. We attempted to prove if schisandrin B (Sch B), a dual inhibitor of P-glycoprotein and multidrug resistance-associated protein 1, could protect against doxorubicin-induced cardiotoxicity, on the premise that Sch B is an enhancer of glutathione redox cycling that may attenuate doxorubicin-induced oxidative stress in the cardiomyocytes.
Mice or rat were dosed with a single injection of doxorubicin (25 mg/kg, i.p.) with or without pretreatment of Sch B. The protective roles of Sch B against doxorubicin-induced cardiac damage were evaluated on the aspects of the release of cardiac enzymes into serum, the formation of malondialdehyde, the activation of matrix metalloproteinase, the structural damage in the left ventricles, the mortality rates, and the cardiac functions.
Pretreatment of Sch B significantly attenuated doxorubicin-induced cardiotoxicities on all the aspects listed above. The underlying mechanism was associated with the effect of Sch B on maintaining the cardiomyocytic glutathione and the activities of superoxide dismutase, and the key enzymes (glutathione peroxidase, glutathione reductase, and glutathione transferase) responsible for glutathione redox cycling, which neutralized doxorubicin-induced oxidative stress.
To the best of our knowledge, Sch B is the only molecule ever proved to function as a cardioprotective agent as well as a dual inhibitor of P-glycoprotein and multidrug resistance-associated protein 1, which is potentially applicable to treat cancers, especially the multidrug-resistant cancers involving doxorubicin or its kin.
Clinical Cancer Research 12/2007; 13(22 Pt 1):6753-60. · 7.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Targeting the "weak point" of cancers, especially the apoptotic/drug resistant cancers, is critical for the success of cancer chemotherapy. We found that the drug resistant cancer cell lines overexpressing P-gp, MRP1, BCRP, Bcl-2 and Bcl-xL are susceptible to shikonin, a necroptotic inducer, despite the fact that they are highly resistant to a variety of anticancer agents such as anthracycline antibiotics, vinca alkaloids, taxanes, epipodophylotoxins, etc. These findings reveal that, although apoptotic/drug resistance is a formidable "stronghold" of cancer against chemotherapy, necroptotic susceptibility is an intrinsic "weak point" of cancer. Therefore, targeting the weakness of cancer by induction of necroptosis may have significant potential in cancer chemotherapy, especially in the apoptotic/drug resistant cancers.