Improved therapeutic efficacy against murine carcinoma by combining honokiol with gene therapy of PNAS-4, a novel pro-apoptotic gene

PNAS-4, a novel pro-apoptotic gene activated during the early response to DNA damage, can inhibit proliferation via apoptosis when overexpressed in some tumor cells. Recent studies have indicated that honokiol can induce apoptosis, inhibit angiogenesis, and suppress tumor growth. In the present study, we investigated whether mouse PNAS-4 (mPNAS-4) could augment the apoptosis of tumor cells induced by honokiol in vitro, and whether the antiangiogenic activity of honokiol and induction of apoptosis by mPNAS-4 could work cooperatively to improve the antitumor efficacy in vivo. In vitro , mPNAS-4 inhibited proliferation of murine colorectal carcinoma CT26 and Lewis lung carcinoma LL2 cells through induction of apoptosis, and significantly augmented the apoptosis of CT26 and LL2 cells induced by honokiol. Compared with treatment with mPNAS-4 or honokiol alone, in vivo systemic administration of an expression plasmid encoding mPNAS-4 and low-dose honokiol significantly suppressed tumor growth through the enhanced induction of apoptosis and the augmented inhibition of angiogenesis. Our data suggest that the combined treatment with mPNAS-4 plus honokiol augments antitumor effects in vitro and in vivo , and that the improved antitumor activity in vivo may be associated with enhanced induction of apoptosis and augmented inhibition of angiogenesis. The present study may provide a novel and effective method for the treatment of cancer. ( Cancer Sci 2009; 100: 1757–1766)     

Synergistic effects of acyclic retinoid and gemcitabine on growth inhibition in pancreatic cancer cells

Pancreatic cancer is a serious healthcare problem worldwide because of its high mortality. Gemcitabine, a DNA synthesis inhibitor, is the standard first-line treatment for advanced pancreatic cancer and is also expected as a key drug for the combination therapy of this malignancy. Retinoids, which are derivatives of vitamin A, exert anti-tumor effects in various types of human malignancies, including pancreatic cancer. This study examined whether combination therapy with gemcitabine and acyclic retinoid (ACR), a new synthetic retinoid, had enhanced anti-tumor efficacy in pancreatic cancer. ACR, 9-cis-retinoic acid and gemcitabine preferentially inhibited the growth of human pancreatic cancer cells (Panc-1 and KP-2) in comparison to PE normal human pancreatic epithelial cells. The combination of ACR plus gemcitabine synergistically inhibited the growth of Panc-1 cells. The combined treatment with these two agents also acted synergistically to induce apoptosis and to inhibit Ras activation in these cancer cells. In vivo, the combination therapy augmented tumor growth inhibition through the induction of apoptosis and inhibition of cell proliferation in tumor tissue. These results suggest that the combination of ACR plus gemcitabine may therefore be an effective regimen for the chemotherapy of pancreatic cancer.     

PNAS-4, a novel pro-apoptotic gene, can potentiate antineoplastic effects of cisplatin

Purpose

PNAS-4, a novel pro-apoptotic gene activated during the early response to DNA damage, can inhibit proliferation via apoptosis when overexpressed in some tumor cells. The objectives of this study were to determine whether PNAS-4 could enhance apoptosis induced by cisplatin besides its induction of apoptosis, and to evaluate the usefulness of combined treatment with mouse PNAS-4 (mPNAS-4) gene therapy and low-dose cisplatin chemotherapy in the inhibition of tumor growth in colon carcinoma (CT26) and Lewis lung carcinoma (LL/2) murine models.

Methods

In this study, the in vitro growth-inhibitory and pro-apoptotic effects of PNAS-4 and/or cisplatin on CT26, LL/2, and SKOV3 cancer cells were assessed by MTT assay, flow cytometric analysis, DNA fragmentation, and morphological analysis, respectively. The in vivo antitumor activity of combined treatment with mPNAS-4 gene therapy and low-dose cisplatin were evaluated in the inhibition of tumor growth in colon carcinoma (CT26) and Lewis lung carcinoma (LL/2) murine models. Tumor volume and survival time were observed. Induction of apoptosis was also assessed in tumor tissues.

Results

In vitro, PNAS-4 inhibited proliferation of colon carcinoma (CT26), Lewis lung carcinoma (LL/2) and human ovarian cancer (SKOV3) cell lines via apoptosis, and significantly enhanced the apoptosis of CT26, LL/2, and SKOV3 cells induced by cisplatin. In vivo systemic administration of expression plasmid encoding mPNAS-4 (pcDNA3.1-mPS) and cisplatin, significantly decreased tumor growth through increased tumor cell apoptosis compared to treatment with mPNAS-4 or cisplatin alone.

Conclusions

Our data suggests that the combined treatment with mPNAS-4 plus cisplatin may augment the induction of apoptosis in tumor cells in vitro and in vivo, and that the augmented antitumor activity in vivo may result from the increased induction of apoptosis. The present study may provide a novel way to augment the antitumor efficacy of cytotoxic chemotherapy.     

Enhanced antitumor efficacy by the combination of emodin and gemcitabine against human pancreatic cancer cells via downregulation of the expression of XIAP in vitro and in vivo

XIAP and NF-κB play an important role in chemotherapy resistance in pancreatic cancer. The purpose of this study was to explore the role of XIAP and NF-κB in potentiating the antitumor effect of gemcitabine by emodin in pancreatic cancer. SW1990 cells were treated by sodium chloride, gemcitabine, emodin or their combination (gemcitabine plus emodin). Cellular proliferation and apoptosis were detected by Cell Counting kit-8 (CCK-8) assay and flow cytometry in?vitro. The combination therapy more significantly inhibited SW1990 cell growth and induced a higher percentage of apoptosis than monotherapy. Gemcitabine upregulated the expression of XIAP and NF-κB, while emodin or emodin plus gemcitabine downregulated them compared to the control group in?vitro. SW1990 cells were used to establish orthotopic pancreatic tumor models in nude mice. Tumor-bearing mice were treated with sodium chloride, emodin, gemcitabine or their combination. After being treated for 4 weeks, the nude mice were imaged with high-resolution positron emission tomography (microPET) and fluorine-18-labeled fluorodeoxyglucose (18F-FDG) to detect the tumor/non-tumor ratio (T/NT ratio) and standard uptake value (SUV). The mice were sacrificed to determine tumor weight. The combination of emodin and gemcitabine showed more significant reduction in the T/NT ratio, SUV and tumor weight compared to monotherapy. The mRNA levels and the protein expression of XIAP and NF-κB were upregulated in the gemcitabine group, while they were downregulated in the emodin group and the combination group in?vivo. Ki-67 prolif-eration index and TUNEL assay results also showed that emodin enhanced tumor apoptosis induced by gemcitabine in?vivo. This study suggests that emodin enhances the antitumor effect of gemcitabine in SW1990 pancreatic cancer in?vitro and in?vivo, which may be via the downregulation of NF-κB expression, thus inhibiting the expression of XIAP.     

环氧化酶-2 抑制剂联合依托泊苷对肺癌细胞增殖凋亡的影响

 目的 探讨环氧化酶-2（COX-2）抑制剂尼米舒利（NIM）与化疗药依托泊苷（VP-16）联用对肺癌细胞增殖和凋亡的影响。方法 培养人肺癌细胞A549：①NIM（25μmol／L）与VP-16（2～32μg／mL）联合，MTT试验观察干预48h后细胞增殖变化及增殖抑制率；②分为对照组、NIM组（25μmol／L）、VP-16组（8μg／mL）和NIM＋VP．16组，观察12h、24h及48h后A549细胞生长情况，描记生长曲线；流式细胞术检测干预48h后细胞凋亡率。结果 ①VP-16能抑制肺癌A549细胞的增殖，且呈量一效关系（r=-0．908，P〈0．01），NIM与VP-16联用后，抑增殖作用增强，二者有相加或协同作用；②NIM及VP-16均可抑制A549细胞的生长，诱导凋亡，二者联用后作用增强。结论 NIM与VP-16联用可增强对肺癌细胞增殖的抑制和凋亡的诱导，二者具有协同抗肿瘤作用。     

Metuzumab enhanced chemosensitivity and apoptosis in non-small cell lung carcinoma

Targeted therapeutics is used as an alternative treatment of non-small cell lung cancer (NSCLC); however, treatment effect is far from being satisfactory, and therefore identification of new targets is needed. We have previously shown that metuzumab inhibit tumor growth in vivo. The present study was performed to investigate the anti-tumor efficacy of metuzumab combined with gemcitabine and cisplatin (GP), paclitaxel and cisplatin (TP) or navelbine and cisplatin (NP) regimens in multiple NSCLC cell lines. Our results demonstrate that, in comparison to single agent metuzumab or GP treated cells, metuzumab combined with GP display inhibitory effects on tumor growth. Furthermore, we found that metuzumab elevated the sensitivity of cell lines to gemcitabine, which was identified by MTT assay. Flow cytometric analysis showed that metuzumab combined with gemcitabine (GEM) treatment led to an obvious G1 arrest and an elevated apoptosis in A549, NCI-H460 and NCI-H520 cells. Western blot analysis also demonstrated a significantly reduced level of cyclin D1, Bcl-2, and an obviously increase level of Bax and full-length caspase-3 in A549, NCI-H460 and NCI-H520 cells treated with metuzumab/gemcitabine combination in comparison with single agent treated cells. In addition, metuzumab/gemcitabine treated A549, NCI-H460 and NCI-H520 cells also demonstrated a significantly increase in deoxycytidine kinase (dCK) protein level compared with single agent metuzumab or gemcitabine treated cells. Xenograft models also demonstrated that this metuzumab/gemcitabine combination led to upregulation of dCK. Taken together, the mechanisms of metuzumab combined with GP repress tumor growth were that the combined treatment significantly inhibited the tumor cell proliferation, apoptosis and cell cycle in vitro and in vivo and at least partially by induction of dCK expression. Our results suggested that metuzumab could significantly enhance chemosensitivity of human NSCLC cells to gemcitabine. Metuzumab/gemcitabine combination treatment may be a potentially useful therapeutic regimen for NSCLC patients.     

Dihydroartemisinin improves the efficiency of chemotherapeutics in lung carcinomas in vivo and inhibits murine Lewis lung carcinoma cell line growth in vitro

Purpose

Dihydroartemisinin (DHA), a semi-synthetic derivative of artemisinin, has exhibited the strongest antimalarial activity among the derivatives of artemisinin. There is growing evidence that DHA has some impact against tumors. Our purpose was to evaluate in vitro antitumoral properties of DHA in the murine Lewis lung carcinoma (LLC) cell line. At the same time, we observed the therapeutic effect of DHA combined with cyclophosphamide (CTX) in the LLC and combined with cisplatin (CDDP) in the human non-small cell lung cancer A549 xenotransplanted carcinoma in vivo.

Methods

Cytotoxicity was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method, apoptosis was measured by AO/EB double staining and flow cytometry. The expression of vascular endothelial growth factor (VEGF) receptor KDR/flk-1 was analyzed by western blotting and RT-PCR. In vivo activity of DHA combined with CTX or CDDP was assayed through tumor growth and metastasis.

Results

Dihydroartemisinin exhibited high anti-cancer activity in LLC cell line. DHA also induced apoptosis of LLC cells and influenced the expression of VEGF receptor KDR/flk-1. Furthermore, in both tumor xenografts, a greater degree of growth inhibition was achieved when DHA and chemotherapeutics were used in combination. The affection by DHA combined CTX on LLC tumor metastasis was significant.

Conclusions

Dihydroartemisinin is a potent compound against LLC cell line in vitro. In vivo, the combination strategy of DHA and chemotherapeutics holds promise for the treatment of relatively large and rapidly growing lung cancers.     

Efficient inhibition of lung cancer in murine model by plasmid-encoding VEGF short hairpin RNA in combination with low-dose DDP

Background

VEGF is a well-validated target for antiangiogenic intervention in cancer. To date, RNAi technology has been proven to be a promising approach for targeted therapy. DDP is frequently used as a first-line drug in chemotherapy for lung cancer but usually causes severe toxicity. In this study, we investigated a novel strategy of administering and combining RNAi mediated VEGF-targeted therapy with DDP for treatment of lung cancer, with the aim of increasing efficacy and decreasing toxicity.

Methods

In this study, a plasmid encoding VEGF shRNA was constructed to knockdown VEGF both in vitro and in vivo. In vitro, specificity and potency of the targeting sequence were validated in A549 lung adenocarcinoma cells by RT-PCR and ELISA assays. In vivo, therapy experiments were conducted on nude mice bearing A549 xenograft tumors. The VEGF shRNA expressing plasmids were administered systemically in combination with low-dose DDP on a frequent basis. The tumor volume and weight were measured. MVD, the number of apoptotic cells and proliferation index in tumor tissues were assessed by CD31, TUNEL and PCNA immunostaining.

Results

The VEGF shRNA was highly effective in attenuating VEGF expression both in vitro and in vivo. The treatment with the VEGF shRNA alone reduced the mean tumor weight by 49.40% compared with the blank control (P < 0.05). The treatment with the VEGF shRNA plus DDP yielded maximal benefits by reducing the mean tumor weight by 83.13% compared with the blank control (P < 0.01). The enhanced antitumor efficacy was associated with decreased angiogenesis and increased induction of apoptosis.

Conclusions

Our study demonstrated synergistic antitumor activity of combined VEGF shRNA expressing plasmids and low-dose DDP with no overt toxicity, suggesting potential applications of the combined approach in the treatment of lung cancer.     

Mast cells and histamine enhance the proliferation of non-small cell lung cancer cells

Non-small cell lung cancer (NSCLC) is the most common form of lung cancer with an extremely low survival rate. It is characterized by a chronic inflammatory process with intense mast cell infiltrate that is associated with reduced survival. The aim of this study was to test the hypothesis that mast cells have an enhancing effect on NSCLC proliferation. To assess the tumor-promoting potential of mast cells, we used the human alveolar basal adenocarcinoma (A549) and the mouse Lewis lung carcinoma (LLC) cell lines, umbilical cord blood-derived mast cells (CBMC) and the mast cell-deficient mouse Sash model. The proliferation rate of A549/LLC cells was markedly increased by mast cells and histamine. Histamine proliferating activity was mediated via H₁, H₂ and H₄ receptors and caused ERK phosphorylation. LLC induced in Sash mice or in wild-type mice treated with the mast cell stabilizer nedocromil sodium displayed an accelerated growth (number of metastic colonies in the lungs, total lung area and lung/total mice weight ratio). In summary, we have shown a significant effect of mast cells and histamine in enhancing NSCLC/LLCX growth in vitro, while in a mouse LLC model in vivo we have found that mast cells are important negative regulators of cancer development. Therefore our results would indicate a pro-tumorogenic effect of the mast cells in vitro on established lung tumor cell lines, and anti-tumorogenic effect in mice at lung cancer induction. In conclusion, mast cell/anti-histamine targeted therapies should carefully consider this dual effect.     

VSV-MP gene therapy strategy inhibits tumor growth in nude mice model of human lung adenocarcinoma

Vesicular stomatitis virus (VSV) matrix protein (MP) can induce in vitro apoptosis of tumor cells in the absence of other viral components. Here, the antitumor activity of VSV-MP against lung adenocarcinoma was investigated in vivo. A pVAX-plasmid DNA encoding VSV-MP and control empty vectors (pVAX) were constructed and wrapped-up with liposome. A549 and Spc-A1 human lung adenocarcinoma cells were transfected with liposomal-VSV-MP (Lip-MP) or Lip-pVAX and then examined for cell viability or apoptosis using Hoechst/propidium iodide staining by flow cytometry, and further demonstrated by caspase/poly ADP-ribose polymerase (PARP) cleavage analysis. For the in vivo study, A549 and Spc-A1 lung carcinoma models in nude mice were established and randomly assigned into three groups to receive eight 2-weekly intravenous administrations of medium alone as control, Lip-pVAX or Lip-MP, respectively. Subsequently, Lip-MP significantly reduced tumor growth and prolonged the survival of tumor-bearing mice compared with Lip-pVAX and control agents (P<0.05), with much higher apoptosis index of both in vivo and in vitro tumor cells, respectively (P<0.05). In addition, in vivo antitumoral effect was associated with natural killer-(NK) cell congregation without evidence of toxicity. These observations suggest that systemically delivering Lip-MP has a specific dual antitumor activity in human lung adenocarcinoma by inducing apoptosis and possibly stimulating NK-cell responses, it may provide a clue for developing new therapeutic approaches against human lung adenocarcinoma.     

Enhanced tumor suppression by an ING4/IL-24 bicistronic adenovirus-mediated gene cotransfer in human non-small cell lung cancer cells

ING4 as a member of inhibitor of growth (ING) tumor suppressor family has potent inhibitory effects on a variety of tumors. Interleukin-24 (IL-24), a cytokine-tumor suppressor, also shows broad-spectrum and tumor-specific antitumor activities. In this report, we constructed an ING4/IL-24 bicistronic adenovirus (Ad-ING4-IL-24) and assessed its combined effect on in vitro and in vivo A549 human non-small cell lung cancer cells. We demonstrated that ING4 and IL-24 combination treatment by adenovirus-mediated ING4 and IL-24 coexpression induced additive growth suppression and apoptosis as well as an overlapping effect on upregulation of P21, P27, Fas, Bax and cleaved Caspases-8, 9, 3 and downregulation of Bcl-2 in in vitro A549 lung carcinoma cells. Moreover, Ad-ING4-IL-24 treatment additively inhibited in vivo A549 lung carcinoma subcutaneous (s.c.) xenografted tumor growth and reduced CD34 and microvessel density in A549 xenografted tumors in athymic nude mice. The enhanced antitumor activity elicited by Ad-ING4-IL-24 was closely associated with the coordinate activation of extrinsic and intrinsic apoptotic pathways and additive inhibition of tumor angiogenesis. Thus, our results indicate that cancer gene therapy combining two or more tumor suppressors such as ING4 and IL-24 may constitute a novel and effective therapeutic strategy for lung carcinoma and other cancers.     

Anti-mesothelin immunotoxin SS1P in combination with gemcitabine results in increased activity against mesothelin-expressing tumor xenografts.

PURPOSE: To determine the antitumor activity of the anti-mesothelin immunotoxin SS1P in combination with gemcitabine against mesothelin-expressing tumor xenografts. EXPERIMENTAL DESIGN: The in vitro activity of SS1P in combination with gemcitabine against the mesothelin-expressing cell line A431/K5 was evaluated using cytotoxicity and apoptosis assays. The antitumor activity of this combination was evaluated in nude mice bearing A431/K5 tumor xenografts. Tumor-bearing mice were treated with different doses and schedules of gemcitabine alone, SS1P alone (0.2 mg/kg i.v. every other day x three doses), or with both agents together, and tumor volumes were measured over time. RESULTS: In vitro studies failed to show the synergy of SS1P plus gemcitabine against the mesothelin-expressing A431/K5 cells. In contrast, in the in vivo setting, there was a marked synergy when SS1P was combined with gemcitabine for the treatment of mesothelin-expressing tumor xenografts. This synergy was present using different doses and schedules of gemcitabine administration. In mice treated with fractionated doses of gemcitabine in combination with SS1P, complete tumor regression was observed in all mice and was long-lasting in 60% of the animals. Also, this antitumor activity was specific to SS1P because HA22, an immunotoxin targeting CD22 not expressed on A431/K5 cells, did not increase the efficacy of gemcitabine. CONCLUSIONS: SS1P in combination with gemcitabine results in marked antitumor activity against mesothelin-expressing tumors. This combination could be potentially useful for the treatment of human cancers that express mesothelin and are responsive to gemcitabine therapy.     

Antiangiogenic treatment with three thrombospondin-1 type 1 repeats versus gemcitabine in an orthotopic human pancreatic cancer model.

PURPOSE: In this study, we investigated the antitumor efficacy of thrombospondin-1 three type 1 repeats (3TSR), the antiangiogenic domain of thrombospondin-1, in comparison and in combination with gemcitabine, in an orthotopic pancreatic cancer model. EXPERIMENTAL DESIGN: Human pancreatic cancer cells were injected into the pancreas of severe combined immunodeficient mice. The animals were treated with 3TSR, gemcitabine, 3TSR plus gemcitabine, or vehicle for 3 weeks. Subsequently, the effects of 3TSR and/or gemcitabine on tumor growth, tumor necrosis, microvessel density, cancer cell proliferation, apoptosis, and endothelial cell apoptosis were analyzed. RESULTS: After 3 weeks of treatment, 3TSR reduced tumor volume by 65%, and gemcitabine by 84%. Tumor volume was not statistically different between gemcitabine group and combinatorial treatment group. Extensive necrotic areas were observed in tumors from 3TSR-treated mice, whereas tumors from gemcitabine and combinatorially treated mice were less necrotic than control tumors. 3TSR reduced tumor microvessel density and increased tumor blood vessel endothelial cell apoptosis. In contrast, gemcitabine induced apoptosis and inhibited proliferation of cancer cells. CONCLUSION: 3TSR, the antiangiogenic domain of thrombospondin-1, showed comparable antitumor efficacy to gemcitabine in a human pancreatic cancer orthotopic mouse model. No synergistic effect was found when the two drugs were combined and possible reasons are discussed in detail. A delicate balance between normalization and excessive regression of tumor vasculature is important when initiating alternative combinatorial regimens for treatment of patients with pancreatic cancer.     

Anti-proliferation Effects of Isorhamnetin on Lung Cancer Cells in Vitro and in Vivo

Background: Isorhamnetin (Iso), a novel and essential monomer derived from total flavones of Hippophaerhamnoides that has long been used as a traditional Chinese medicine for angina pectoris and acute myocardialinfarction, has also shown a spectrum of antitumor activity. However, little is known about the mechanisms ofaction Iso on cancer cells. Objectives: To investigate the effects of Iso on A549 lung cancer cells and underlyingmechanisms. Materials and Methods: A549 cells were treated with 10~320 μg/ml Iso. Their morphological andcellular characteristics were assessed by light and electronic microscopy. Growth inhibition was analyzed byMTT, clonogenic and growth curve assays. Apoptotic characteristics of cells were determined by flow cytometry(FCM), DNA fragmentation, single cell gel electrophoresis (comet) assay, immunocytochemistry and terminaldeoxynucleotidyl transferase nick end labeling (TUNEL) . Tumor models were setup by transplanting Lewislung carcinoma cells into C57BL/6 mice, and the weights and sizes of tumors were measured. Results: Isomarkedly inhibited the growth of A549 cells with induction of apoptotic changes. Iso at 20 μg/ml, could induceA549 cell apoptosis, up-regulate the expression of apoptosis genes Bax, Caspase-3 and P53, and down-regulatethe expression of Bcl-2, cyclinD1 and PCNA protein. The tumors in tumor-bearing mice treated with Iso weresignificantly smaller than in the control group. The results of apoptosis-related genes, PCNA, cyclinD1 and otherprotein expression levels of transplanted Lewis cells were the same as those of A549 cells in vitro. Conclusions:Iso, a natural single compound isolated from total flavones, has antiproliferative activity against lung cancer invitro and in vivo. Its mechanisms of action may involve apoptosis of cells induced by down-regulation of oncogenesand up-regulation of apoptotic genes.     

Enhanced antitumor effect of cisplatin in human NSCLC cells by tumor suppressor LKB1

LKB1 is a novel candidate tumor suppressor gene in lung cancer. In this study, we evaluated the effect of cationic liposomes (LPs)-mediated LKB1 gene (LPs-pVAX-LKB1) on low-dose cisplatin (cis-diamminedichloroplatinum)-mediated antitumor activity in lung cancer, both in vitro and in vivo. Our study demonstrated that cationic LPs-mediated LKB1 gene therapy could sensitize the response of lung cancer cells to cisplatin, and significantly induce apoptosis and inhibit proliferation, invasion and metastasis, compared with control groups. Combined treatment with intratumoral administration of Lps-pVAX-LKB1 and intraperitoneal injection of low-dose cisplatin into subcutaneous A549 lung tumor xenograft resulted in significant (P<0.01) inhibition of tumor growth. Furthermore, combined treatment with intravenous injections of Lps-pVAX-LKB1 and intraperitoneal injection of low-dose cisplatin into mice bearing experimental A549 lung metastasis demonstrated significant (P<0.01) decrease in the number of lung metastatic tumor nodules. Mice life spans of combination treatment group were also dramatically prolonged, compared with controls. Further studies indicated that LKB1-enhancing cisplatin-mediated antitumor effects might be associated with the upregulation of p-p53 and p-JNK, and downregulation of p-mammalian target of rapamycin, matrix metalloproteinase (MMP)-2 and MMP-9. This study suggests that the combination of LKB1 gene therapy with low-dose cisplatin-based chemotherapy may be a potent therapeutic strategy for lung cancer.     

Synergistic antitumor effects of liposomal honokiol combined with cisplatin in colon cancer models

Honokiol, a novel antitumor agent, may induce apoptosis and inhibit the growth of vascular endothelium in a number of tumor cell lines and xenograft models. It has been proposed that the antitumor effects of chemotherapy may be increased in combination with an antiangiogenesis agent as an anticancer strategy. In the present study, we examined the potential of honokiol to increase the antitumor effect of cisplatin (DDP) when the agent and drug were combined in murine CT26 colon cancer models, and investigated the underlying mechanism. Liposomal honokiol (LH) was prepared, and female BALB/c?mice were administered LH at various doses to determine the optimum doses for honokial. Evaluation of cell apoptosis was analyzed using flow cytometry. Honokiol was encapsulated with liposome to improve its water insolubility. In?vitro, LH inhibited the proliferation of CT26 cells via apoptosis and significantly enhanced the DPP-induced apoptosis of CT26 cells. In?vivo, the systemic administration of LH plus DDP resulted in the inhibition of subcutaneous tumor growth beyond the effects observed with either LH or DDP alone. This growth reduction was associated with elevated levels of apoptosis (TUNEL staining) and reduced endothelial cell density (CD31 staining) compared with either treatment alone. Collectively, these findings indicate that LH may augment the induction of apoptosis in CT26 cells in?vitro and in?vivo, and this combined treatment has exhibited synergistic suppression in tumor progression according to the synergistic analysis. The present study may be significant to future exploration of the potential application of the combined approach in the treatment of colon cancer.     

E phage gene transfection enhances sensitivity of lung and colon cancer cells to chemotherapeutic agents

The E gene from ΦX174 encodes a membrane protein with a toxic domain that leads to a decrease in the tumour cell growth rate. With the aim of improving the antitumour effect on lung and colon cancer cells of the currently used chemotherapeutic drugs such as gemcitabine, carboplatin and paclitaxel, and 5-fluorouracil (5FU) plus folinic acid (FA) with irinotecan or oxaliplatine, we investigated a new combined therapy using these drugs associated to the transfection of E gene. Our results showed that E gene was able to decrease proliferation rate in A-549 and T-84 cells by inducing apoptotic the mitochondrial pathway. Significantly greater inhibition of proliferation was obtained using drugs in combination with E gene in comparison to single-agent treatments or controls. E gene combined with paclitaxel had the greatest effect on A-549 cells and combined with 5FU/FA/oxaliplatin on T-84 cells. Antitumour mechanisms of the chemotherapeutic drugs were enhanced by E gene, which itself has direct oncolytic effects inducing A-549 and T-84 apoptosis. Our in vitro results indicate that the combined therapy of E gene and cytotoxic drugs may be of potential therapeutic value as a new strategy for patients with advanced lung and colon cancer.     

Interaction between gemcitabine and topotecan in human non-small-cell lung cancer cells: effects on cell survival, cell cycle and pharmacogenetic profile

The pyrimidine analogue gemcitabine is an established effective agent in the treatment of non-small-cell lung cancer (NSCLC). The present study investigates whether gemcitabine would be synergistic with the topoisomerase I inhibitor topotecan against the NSCLC A549 and Calu-6 cells. Cells were treated with gemcitabine and topotecan for 1 h and the type of drug interaction was assessed using the combination index (CI). Cell cycle alterations were analysed by flow cytometry, while apoptosis was examined by the occurrence of DNA internucleosomal fragmentation, nuclear condensation and caspase-3 activation. Moreover, the possible involvement of the PI3K-Akt signalling pathway was investigated by the measurement of Akt phosphorylation. Finally, quantitative, real-time PCR (QRT-PCR) was used to study modulation of the gemcitabine-activating enzyme deoxycytidine kinase (dCK) and the cellular target enzyme ribonucleotide reductase (RR). In results, it was found that simultaneous and sequential topotecan --> gemcitabine treatments were synergistic, while the reverse sequence was antagonistic in both cell lines. DNA fragmentation, nuclear condensation and enhanced caspase-3 activity demonstrated that the drug combination markedly increased apoptosis in comparison with either single agent, while cell cycle analysis showed that topotecan increased cells in S phase. Furthermore, topotecan treatment significantly decreased the amount of the activated form of Akt, and enhanced the expression of dCK (+155.0 and +115.3% in A549 and Calu-6 cells, respectively), potentially facilitating gemcitabine activity. In conclusion, these results indicate that the combination of gemcitabine and topotecan displays schedule-dependent activity in vitro against NSCLC cells. The gemcitabine --> topotecan sequence is antagonistic while drug synergism is obtained with the simultaneous and the sequential topotecan --> gemcitabine combinations, which are associated with induction of decreased Akt phosphorylation and increased dCK expression.