Human Cancer Chemotherapy Research Articles

Pharmacogenomics of Human ABC Transporter ABCC11 (MRP8): Potential Risk of Breast Cancer and Chemotherapy Failure

Some genetic polymorphisms of human ABC transporter genes are reportedly related to the risk of certain diseases and patients’ responses to medication. Human ABCC11 functions as an ATP-dependent efflux pump for amphipathic anions. One non-synonymous SNP 538G>A (Gly180Arg) has been found to greatly affect the function and stability of de novo synthesized ABCC11 (Arg180) variant protein. The SNP variant lacking N-linked glycosylation is recognized as a misfolded protein in the endoplasmic reticulum (ER) and readily undergoes proteasomal degradation. This ER-associated degradation of ABCC11 protein underlies the molecular mechanism of affecting the function of apocrine glands. On the other hand, the wild type (Gly180) of ABCC11 is associated with wettype earwax, axillary osmidrosis, colostrum secretion from the mammary gland, and the potential susceptibility of breast cancer. Furthermore, the wild type of ABCC11 reportedly has ability to efflux cyclic nucleotides and nucleoside-based anticancer drugs. The SNP (538G>A) of the ABCC11 gene is suggested to be a clinical biomarker for prediction of chemotherapeutic efficacy. Major obstacle to the successful chemotherapy of human cancer is development of resistance, and nucleoside-based chemotherapy is often characterized by inter-individual variability. This review provides an overview about the discovery and the genetic polymorphisms in human ABCC11. Furthermore, we focus on the impact of ABCC11 538G>A on the apocrine phenotype, patients’ response to nucleoside-based chemotherapy, and the potential risk of breast cancer.

Cancer Chemotherapy: An Annotated History

Treating cancer with drugs is an ancient art, but it is from discoveries made during and after the Second World War that real clinical success with cancer chemotherapy has occurred. Human and veterinary cancer chemotherapy have coevolved in the context of fascinating historical, political, and scientific events created by equally fascinating individuals.

Multigene Assays to Improve Assessment of Recurrence Risk and Benefit From Chemotherapy in Early-Stage Colon Cancer: Has the Time Finally Arrived, or Are We Still Stage Locked?

growth of cardiac myocytes: Persistence of ErbB2 and ErbB4 expression in neonatal and adult ventricular myocytes. J Biol Chem 273:10261-10269, 1998 14. de Korte MA, de Vries EG, Lub-de Hooge MN, et al: 111Indiumtrastuzumab visualises myocardial human epidermal growth factor receptor 2 expression shortly after anthracycline treatment but not during heart failure: A clue to uncover the mechanisms of trastuzumab-related cardiotoxicity. Eur J Cancer 43:2046-2051, 2007 15. Buzdar AU, Valero V, Ibrahim NK, et al: Neoadjuvant therapy with paclitaxel followed by 5-fluorouracil, epirubicin, and cyclophosphamide chemotherapy and concurrent trastuzumab in human epidermal growth factor receptor 2-positive operable breast cancer: An update of the initial randomized study population and data of additional patients treated with the same regimen. Clin Cancer Res 13:228-233, 2007 16. Gianni L, Eiermann W, Semiglazov V, et al: Neoadjuvant chemotherapy with trastuzumab followed by adjuvant trastuzumab versus neoadjuvant chemotherapy alone, in patients with HER2-positive locally advanced breast cancer (the NOAH trial): a randomised controlled superiority trial with a parallel HER2negative cohort. Lancet 375:377-384, 2010

Cytostatic activity of the duplex drug linking 2′-deoxy-5-fluorouridine (5FdU) with 3′-C-ethynylcytidine (ECyd) against gastric adenocarcinoma cell lines

The cytostatic potential of the new duplex drug 2'-deoxy-5-fluorouridylyl-(5'5')-3'-C-ethynylcytidine (5FdU(5'-5')ECyd) was evaluated in comparison to those of 5-fluorouracil (5FU), 2'-deoxy-5-fluorourindine (5FdU), 3'-C-ethynylycytidine (ECyd), cisplatin, an equimolar mixture of 5FdU + ECyd and a three component-mixture of 0.75 μM epirubicin/0.90 μM cisplatin/3.0 μM 5FU (ECF) by incubation of the two human gastric adenocarcinoma cell lines 23132/87 and MKN-45. The molar composition of ECF was taken from data of a triple combination chemotherapy for human gastric cancer. Time and dose depending inhibition of cell growth was determinated using the CASY technology. A growth decrease of both cell lines from 100% to about 20% was observed by treatment with ECF over a course of 14 days. This result provided basis to estimate the cytostatic potential of all tested drugs and combinations thereof. Corresponding high activities in respect to ECF were achieved by incubation of 23132/87 cells with single drugs 49 μM 5FU, 10 μM cisplatin, 3.4 μM 5FdU, 0.65 μM ECyd, the mixture 0.32 μM 5FdU + 0.32 μM ECyd and 0.32 μM 5FdU(5'-5')ECyd. The less sensitive MKN-45 cells require a 1.5-4 fold higher dose of the standard chemotherapeutics in order to achieve an equivalent cytostatic effect, in respect to the 23132/87 cell line,. However, the effect of the duplex drugs on MKN-45 cells was gained with a 5-fold lower dose than ECF. Due to its high cytostatic potential the duplex drug, which covalently links two active anticancer compounds, could be a new therapeutic alternative for chemotherapy in gastric cancer, currently treated with different combinations.

γ-Tocotrienol modulates the paracrine secretion of VEGF induced by cobalt(II) chloride via ERK signaling pathway in gastric adenocarcinoma SGC-7901 cell line

Hypoxia is a common characteristic feature of solid tumors, and carcinoma cells are known to secrete many growth factors. These growth factors, such as vascular endothelial growth factor (VEGF), play a major role in the regulation of tumor angiogenesis and metastasis. In this study, the effect of γ-tocotrienol, a natural product commonly found in palm oil and rice bran, on the accumulation of HIF-1α protein and the paracrine secretion of VEGF in human gastric adenocarcinoma SGC-7901 cell line induced by cobalt(II) chloride (as a hypoxia mimic) was investigated. These results showed that cobalt(II) chloride induced the high expression of VEGF in SGC-7901 cells at dose of 150 μmol/L for 24 h. Both basal level and cobalt(II) chloride-induced HIF-1α protein accumulation and VEGF paracrine secretion were inhibited in SGC-7901 cells treated with γ-tocotrienol at 60 μmol/L treatment for 24 h. U0126, a MEK1/2 inhibitor, decreased the expression of HIF-1α protein and the paracrine secretion of VEGF under normoxic and hypoxic conditions. In this study, γ-tocotrienol also significantly inhibited the hypoxia-stimulated expression of phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2). The mechanism seems to involve in inhibiting hypoxia-mediated activation of p-ERK1/2, it leads to a marked decrease in hypoxia-induced HIF-1α protein accumulation and VEGF secretion. These data suggest that HIF-1α/VEGF could be a promising target for γ-tocotrienol in an effective method of chemoprevention and chemotherapy in human gastric cancer.

3,3′,4,5,5′-pentahydroxy-trans-stilbene, a resveratrol derivative, induces apoptosis in colorectal carcinoma cells via oxidative stress

Resveratrol exhibits anti-tumor properties against different types of cancer. In this study, several polyhydroxylated resveratrol derivatives were prepared with the aim of discovering new leading compounds with clinical potential for human colon cancer chemotherapy. Among these compounds, 3,3',4,5,5'-pentahydroxy-trans-stilbene (PHS) displayed the most potent cytotoxicity and triggered apoptosis in HT-29 cells as evidenced by increased poly(ADP-ribose) polymerase (PARP) cleavage, elevated levels of cytoplasmic nucleosomes and DNA fragmentation. Further mechanistic analysis revealed that PHS-induced apoptosis was caspase-dependent and mediated by its pro-oxidative action through up-regulation of reactive oxidative species generation and depletion of intracellular glutathione.

Abstract 3452: Role of P-glycoprotein in carcinogenesis

Abstract Cancer accounts for nearly one-quarter of deaths in the United States, exceeded only by heart diseases. Polycyclic aromatic hydrocarbons (PAHs) are commonly found in our environment and appear to be carcinogenic by genotoxic mechanisms. Several studies show that over-expression of P-glycoprotein (Pg-p, coded by mdr1) is associated with the development of various cancers. High expression of the mdr1 gene has been reported in many human cancers such as in breast, liver, colon, kidney and brain. Many molecular and cellular studies have revealed the ability of dietary phytochemicals in vegetables and fruits to reduce the risk of cancer. The abundant and inexpensive dietary phytochemicals are being explored as Pg-p modulators in cancer chemoprevention and chemotherapy. In the present study, we investigated the role of P-gp in cancer development. We also studied whether the inhibition of P-gp function could reduce the development of cancer. The wild type (C57BL/6J) mice were exposed to the environmental PAH, 7, 12-dimethylbenz(a)anthracene (DMBA) and dietary phytochemicals, alone and in combination. The hepatic and mammary gene expressions of P-gp, Pregnane X receptor (PXR), and CYP3A11 were analyzed. The environmental PAHs induced hepatic and mammary expressions of P-gp and associated genes in mice, compared to controls. Administration of dietary phytochemicals inhibited the P-gp expression significantly. Induction of specific DNA adducts were also observed in hepatic and mammary tissues of mice treated with PAHs and phytochemicals. These studies show a potential for development of dietary phytochemicals as Pg-p modulators in chemoprevention and chemotherapy of human cancers. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3452.

Abstract 3337: Characterization of tumor initiating cells response to chemotherapy in human colorectal cancer

Abstract Current chemotherapy for colorectal cancer is still based in combined 5-fluorouracil (5-FU) and oxaliplatin administration with or without other new drugs. However, an important percentage of patients show resistance to this treatment. Tumor initiating cells (TICs) or cancer stem cells, are able to reconstitute a tumor of similar characteristics to the primary tumor after transplantation into immunodeficient mice. TICs show the ability to self-renew and give rise to non-TIC progeny, supporting the tumor growth. Recent studies suggest that TICs may be intrinsically resistant to therapy, leading to tumor relapse after chemotherapy. To gain insight into the dynamics of TICs during tumor progression and in response to chemotherapy, we have orthotopically implanted and perpetuated in nude mice 14 human colorectal carcinomas (CRC) that produce local and distal dissemination. We have characterized the chemotherapy response in 7 of these perpetuated xenografts. Four of these tumors showed a significant reduction of growth after 5-FU and oxaliplatin combined treatment (FUOX treatment) compared to the correspondent non-treated control tumors. To evaluate the role of TICs in chemotherapy response, we analyzed survival of non-TICs and TICs -identified by CD133/CD44/EpCAM cell surface markers- after chemotherapy. Our results show that, although in 2 out of 4 of the tumors showing efficient response to chemotherapy, TICs were more resistant to FUOX than the rest of tumor cells, in the other 2 tumors TICs and non-TICs were similarly sensitive to treatment. These results indicate that the resistance to chemotherapy is not an intrinsic characteristic of TICs and offer the possibility to characterize sensitive and resistant TICs to FUOX to identify genes and pathways directly involved in chemoresistance. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3337.

Inhibition of autophagy augments 5-fluorouracil chemotherapy in human colon cancer in vitro and in vivo model

Although 5-fluorouracil (5-FU)-based adjuvant chemotherapy is widely used in the treatment of colorectal cancer, novel therapeutic strategies need to be explored. It has been reported that autophagy is extensively implicated in cancer. However, the function of autophagy is not fully understood. In the present study, apoptosis induced by 5-FU in 3 human colon cancer cell lines (HCT116, DLD-1, and DLD-1/5-FU (a specific 5-FU-resistant sub-line)) was measured using MTT assay, DNA fragmentation assay, Hoechst 33342 staining, and caspase-3 immunoblotting. The autophagy activation induced by 5-FU treatment was revealed by microtubule-associated protein 1 light chain 3 (LC3) immunofluorescence and immunoblotting and p62 immunoblotting. Inhibition of autophagy by 3-methyladenine (3-MA) or small interference RNA targeting Atg7 (Atg7 siRNA) significantly augmented 5-FU-induced apoptosis. This synergistic effect of 5-FU and 3-MA was further confirmed in the DLD-1 xenograft tumour model. Tumour growth was suppressed more significantly with combination treatment than 5-FU treatment alone. In conclusion, autophagy was activated as a protective mechanism against 5-FU–induced apoptosis and its inhibition could be a promising strategy for adjuvant chemotherapy in colon cancer.

Effect of type 1 insulin-like growth factor receptor targeted therapy on chemotherapy in human cancer and the mechanisms involved

Chemotherapy is administered only to patients with advanced cancers, typically to modest avail. Hence, the search for innovative approaches to treat cancer is growing rapidly. One such approach involves targeting molecular pathways identified as encouraging tumor growth and maintenance, particularly the type 1 insulin-like growth factor (IGF-1) and its receptor (IGF-1R) pathway that is important in conferring chemoresistance. This study focuses on IGF-1R targeted therapy, which will enhance chemotherapy efficacy, through reviewing recent literature from PubMed and Medline databases. This review examines data and strategies addressing an approach conquering chemoresistance through the combination of IGF-1R targeted therapy and chemotherapy in cancer patients, as well as the mechanisms by which IGF-1R acts as a target. This will impact on future research on treatment selection, thereby improving patient prognosis.

Breast Cancer Stem Cells Identified by ALDH1 Expression Were Associated with Resistance to Sequential Paclitaxel and Epirubicin-Based Chemotherapy for Human Breast Cancers.

Abstract Background: Breast cancer stem cells have been demonstrated to be associated with resistance to chemotherapy in vitro, but their clinical significance has yet to be examined in human breast cancers. The aim of this study was to investigate whether breast cancer stem cells were clinically associated with chemo-resistance or not.Material and Methods: The subjects recruited for this study comprised 108 primary invasive breast cancer patients treated with neoadjuvant chemotherapy (NAC) consisting of sequential paclitaxel and epirubicin-based chemotherapy. Cancer stem cells were identified by immunohistochemical staining of CD44/CD24 or ALDH1 in tumor tissues obtained before and after NAC.Results: The pathological complete response (pCR) was achieved in 30 patients (27.8%) of the 108 patients treated with NAC. ALDH1 positive tumors were significantly associated with a low pCR rate (9.5% vs. 32.2%; P = 0.037), but there was no significant association between CD44+/CD24- tumor cell proportions and pCR rates. Changes in the proportion of CD44+/CD24- tumor cells or ALDH1 positive tumor cells before and after NAC were examined in 78 patients who did not achieve pCR. The proportion of ALDH1 positive tumor cells significantly increased (p<0.001) after NAC, but no significant change was observed in the proportion of CD44+/CD24- tumor cells before and after NAC. In addition, we were able to show, by multivariate analysis, that tumors with negative ER, high Ki67, and negative ALDH1 were significantly more likely to achieve pCR.Discussion: Our findings suggest that breast cancer stem cells identified as ALDH1 positive, but not CD44+/CD24-, play a significant role in resistance to chemotherapy. ALDH1 positive tumor cells are likely to serve as a better marker for breast cancer stem cells than CD44+/CD24- tumor cells for the prediction of resistance to chemotherapy. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1084.

Smart drug-loaded polymer gold nanoshells for systemic and localized therapy of human epithelial cancer.

Near-infrared-light-sensitive multifunctional smart drug-loaded polymer gold nanoshells are fabricated as advanced prototypes, composed of chemotherapeutic agents (therapeutic antibody and anticancer drug-loaded polymeric nanoparticles) for systemic chemotherapy of human epithelial cancer and a polymer-based gold nanoshell for localized photothermal treatment by NIR light.

The cyclin-dependent kinase inhibitor 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole induces nongenotoxic, DNA replication-independent apoptosis of normal and leukemic cells, regardless of their p53 status

BackgroundCurrent chemotherapy of human cancers focuses on the DNA damage pathway to induce a p53-mediated cellular response leading to either G1 arrest or apoptosis. However, genotoxic treatments may induce mutations and translocations that result in secondary malignancies or recurrent disease. In addition, about 50% of human cancers are associated with mutations in the p53 gene. Nongenotoxic activation of apoptosis by targeting specific molecular pathways thus provides an attractive therapeutic approach.MethodsNormal and leukemic cells were evaluated for their sensitivity to 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) through cell viability and caspase activation tests. The apoptotic pathway induced by DRB was analysed by immunfluorescence and immunoblot analysis. H2AX phosphorylation and cell cycle analysis were performed to study the dependance of apoptosis on DNA damage and DNA replication, respectively. To investigate the role of p53 in DRB-induced apoptosis, specific p53 inhibitors were used. Statistical analysis on cell survival was performed with the test of independence.ResultsHere we report that DRB, an inhibitor of the transcriptional cyclin-dependent kinases (CDKs) 7 and 9, triggers DNA replication-independent apoptosis in normal and leukemic human cells regardless of their p53 status and without inducing DNA damage. Our data indicate that (i) in p53-competent cells, apoptosis induced by DRB relies on a cytosolic accumulation of p53 and subsequent Bax activation, (ii) in the absence of p53, it may rely on p73, and (iii) it is independent of ATM and NBS1 proteins. Notably, even apoptosis-resistant leukemic cells such as Raji were sensitive to DRB.ConclusionOur results indicate that DRB represents a potentially useful cancer chemotherapeutic strategy that employs both the p53-dependent and -independent apoptotic pathways without inducing genotoxic stress, thereby decreasing the risk of secondary malignancies.

Predictive factors for anthracycline-based chemotherapy for human breast cancer

Predictive factors for anthracycline-based chemotherapy have yet to be incorporated into daily practice. Meta-analyses of studies using anthracycline-based treatment regimens have shown an improved prognosis for human epidermal growth factor receptor type 2 (HER2)-positive tumors, but not for HER2-negative tumors compared with results of non-anthracycline regimens. Currently it is believed that the positive association between HER2 status and anthracycline sensitivity is indirect, that is, their association may be mediated through topoisomerase II alpha (TOP2A), a target molecule of anthracyclines, since TOP2A is near HER-2 and co-amplification of the TOP2A gene frequently occurs in HER2-amplified tumors. This strongly suggests that TOP2A gene amplification is a predictive factor for anthracyline-based regimens. The Collaborative Study Group of Scientific Research of the Japanese Breast Cancer Society has demonstrated that TOP2A-positive and BRCA1-negative subsets evaluated by immunohistochemical staining show a significantly higher pathological complete response when treated with preoperative epirubicin-containing regimens. Combining these findings with the observation that triple-negative tumors and basal-like tumors respond to anthracycline treatment suggests that not only HER2-positive tumors but also a distinct subset of HER2-negative tumors may be sensitive to anthracycline-based regimens.

Heat Shock Protein 27 as a New Therapeutic Target for Radiation Sensitization of Head and Neck Squamous Cell Carcinoma

In a wide range of human cancers, increased levels of heat shock protein 27 (Hsp27) are closely associated with tumorigenesis, metastasis, resistance to anticancer therapeutics, and thus poor prognosis. In this study, we evaluate the radiosensitizing effects of Hsp27 gene silencing using OGX-427, a second-generation antisense oligonucleotide (ASO), on the radioresistant head and neck squamous cell carcinoma (HNSCC) SQ20B cells. In vitro, the downregulation of Hsp27 significantly enhanced radiation-induced apoptotic and clonogenic death, and promoted Akt inactivation. In vivo, combining OGX-427 with local tumor irradiation (5 x 2 Gy) led to a significant regression of SQ20B tumors related to a high rate of apoptosis and decreased levels of glutathione antioxidant defenses. Increasing the total radiation dose (15 x 2 Gy) significantly amplified the radiosensitizing effect of OGX-427. Treatment of tumors with OGX-427 plus radiation resulted in a decrease in angiogenesis associated with a reduced activation of the Akt pathway. Furthermore, the combined treatment enhanced the survival of SQ20B-bearing mice and showed no signs of acute and delayed toxicity. Our findings demonstrate for the first time that Hsp27 knockdown enhances the cytotoxic effects of radiotherapy in vivo and provide preclinical proof of principle for clinical trials using Hsp27 antisense technology in the treatment of patients with HNSCC radioresistant cancers.

V-PROLI/NO, a nitric oxide donor prodrug, protects liver cells from arsenic-induced toxicity.

Inorganic arsenic shows great promise in human cancer chemotherapy, although hepatotoxicity is a major limiting side-effect. O(2)-Vinyl 1-[2-(Carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate (V-PROLI/NO) [Correction added after publication 19 December 2008: 1-[2-(Carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate (V-PROLI/NO) was corrected to O(2)-Vinyl 1-[2-(Carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate (V-PROLI/NO)] is a nitric oxide (NO) donor prodrug that is metabolized by liver cytochromes P450 to release NO. Other NO-releasing agents have been shown to mitigate arsenic toxicity. Thus, the effects of V-PROLI/NO pretreatment on the toxicity of inorganic arsenic (as NaAsO(2)) were studied in vitro in a human liver (HepG2) cell line. HepG2 cells acted upon the prodrug to release NO, as assessed by nitrite levels, in a dose- and time-dependent fashion to maximal levels of 57-fold above control levels. In cells pretreated with V-PROLI/NO (200 microM, 24 h) then exposed to arsenic for an additional 24 h, arsenic was much less toxic (LC(50) = 151.9 +/- 5.9 microM) than in control cells (LC(50) = 90.5 +/- 6.5 microM) and the reduced cytolethality was directly related to the level of NO produced. V-PROLI/NO also increased CYP2E1 transcriptional expression in a dose-dependent manner and CYP2E1 expression was directly related to the level of NO produced and the reduction in arsenic cytotoxicity. V-PROLI/NO pretreatment markedly reduced arsenic-induced apoptosis as measured by DNA fragmentation. Pretreatment with V-PROLI/NO suppressed phosphorylation of JNK1/2 after arsenic exposure. Arsenic increased metallothionein, a metal-binding protein important in arsenic tolerance, and V-PROLI/NO pretreatment caused additional increases in metallothionein levels. Thus, the prodrug, V-PROLI/NO, protects against arsenic toxicity in cultured human liver cells, reducing cytolethality, apoptosis and dysregulation of mitogen-activated protein kinases, through generation of NO formed after metabolism by liver cell enzymes, possibly including CYP2E1.

Potent modulation of P‐glycoprotein activity by naturally occurring phenylbutenoids from Zingiber cassumunar

Five phenylbutenoid derivatives from the rhizomes of Zingiber cassumunar Roxb. (Zingiberaceae) were evaluated for their P-glycoprotein (P-gp) inhibitory effects in a P-gp over-expressing multidrug resistant (MDR) human breast cancer cell line, MCF-7/ADR. As a result, a phenylbutenoid dimer, (+/-)-trans-3-(3,4-dimethoxyphenyl)-4-[(E)-3,4-dimethoxystyryl]cyclohex-1-ene (1), exhibited highly potent P-gp inhibitory activity, decreasing the IC(50) value of daunomycin (DNM) to 4.31 +/- 0.40 microm in the cells (DNM IC(50) = 37.1 +/- 0.59 microm). The positive control, verapamil decreased the IC(50) value of DNM to 6.94 +/- 0.40 microm. Three phenylbutenoid monomers, 2-4 from this plant, also resulted in a significant decrease in the IC(50) values of DNM compared with the control. In particular, compound 1 markedly enhanced [(3)H]-DNM accumulation and significantly reduced [(3)H]-DNM efflux compared with the control, and this effect was more potent than that of verapamil, a well-known P-gp inhibitor. These results suggest that compound 1 of Z. cassumunar can be developed as a potent chemo-sensitizing agent that reverses P-gp-mediated MDR in human cancer chemotherapy.

Copy-Number Analysis of Topoisomerase and Thymidylate Synthase Genes in Frozen and FFPE DNAs of Colorectal Cancers

Archived formalin-fixed, paraffin-embedded specimens represent an important resource for pharmacogenomic analysis in retrospective clinical studies but the quality of results from formalin-fixed, paraffin-embedded samples is of concern due to the fact of the degradation of DNAs and RNAs from formalin-fixed, paraffin-embedded tissues. In the present study, we used DNA from fresh frozen as well as formalin-fixed, paraffin-embedded tumor to detect copy-number changes in colorectal cancer, and our data shows that formalin-fixed, paraffin-embedded DNAs were able to deliver reliable copy-number data, and that quantitative PCR had the ability to detect copy-number changes from deletion to amplification, with high concordance of copy-number calls among formalin-fixed, paraffin-embedded and frozen DNAs. The amplification of topoisomerase I and deletion of thymidylate synthase were found in 23% (12/52) and 27% (14/52) of colorectal cancers, but EGF receptor amplification was not common (5/52, <10%). Among 52 colorectal cancers, 31 tumors were both topoisomerase I and thymidylate synthase diploid, which may have a worse outcome for tumor chemotherapy; and there were five tumors with favorable genomics (topoisomerase I amplification and thymidylate synthase deletion). Furthermore, topoisomerase I-amplified tumors had a two-times higher RNA level and a nearly twofold higher protein expression level than did the diploid tumors (p < 0.001 and 0.01, respectively), but there were no correlations between copy-number status and RNA or protein level for thymidylate synthase. Our study suggests a potential pharmacogenomic influence of topoisomerase I copy-number alteration on its RNA/protein expressions, which could be reflected on tumor response to chemotherapy in human colorectal cancer.

Rapid identification and high sensitive detection of cancer cells on the gold nanoparticle interface by combined contact angle and electrochemical measurements

In this study, we have proposed a novel strategy for the rapid identification and high sensitive detection of different kinds of cancer cells by means of electrochemical and contact angle measurements. A simple, unlabeled method based on the functionalized Au nanoparticles (GNPs) modified interface has been utilized to distinguish the different cancer cells, including lung cancer cells, liver cancer cells, drug sensitive leukemia K562/B.W cells and drug resistant leukemia K562/ADM cells. The relevant results indicate that under optimal conditions, this method can provide the quantitative determination of cancer cells, with a detection limit of ∼10 3 cells mL −1. Our observations demonstrate that the difference in the hydrophilic properties for target cellular surfaces and in the uptake efficiency of the anticancer drug daunorubicin for different cancer cells could be readily chosen as the elements of cancer identification and sensitive detection. This raises the possibility to advance the promising clinic diagnosis and monitoring of tumors with the aim of successful chemotherapy of human cancers.

Molecular targeting of Bcl-2 overcomes prostate cancer cell adaptation to XIAP gene downregulation

X-linked inhibitor of apoptosis (XIAP) is a suppressor of apoptosis that supports an increased survival and resistance to chemotherapy of human prostate cancer (PCa) cells. Effects of transient (24 h) and chronic (beyond 1 month) downregulation of XIAP in DU145 hormone refractory prostate cancer (HRPC) cells were studied. We found that transient downregulation of XIAP by siRNAs resulted in an increase of apoptosis and a decrease in Bcl-2 levels and sensitized PCa cells to cisplatin. XIAP downregulation by shRNA vector stable transfection led to upregulation of Bcl-2 protein. Our results identify the adaptability of PCa cells to chronic loss of XIAP in part through upregulation of Bcl-2 and indicate that multitargeting approach is the most effective application in the chemotherapy of human HRPC.