Maximal Margin Support Vector Machine for Feature Representation and Classification.

High-dimensional small sample size data, which may lead to singularity in computation, are becoming increasingly common in the field of pattern recognition. Moreover, it is still an open problem how to extract the most suitable low-dimensional features for the support vector machine (SVM) and simultaneously avoid singularity so as to enhance the SVM's performance. To address these problems, this article designs a novel framework that integrates the discriminative feature extraction and sparse feature selection into the support vector framework to make full use of the classifiers' characteristics to find the optimal/maximal classification margin. As such, the extracted low-dimensional features from high-dimensional data are more suitable for SVM to obtain good performance. Thus, a novel algorithm, called the maximal margin SVM (MSVM), is proposed to achieve this goal. An alternatively iterative learning strategy is adopted in MSVM to learn the optimal discriminative sparse subspace and the corresponding support vectors. The mechanism and the essence of the designed MSVM are revealed. The computational complexity and convergence are also analyzed and validated. Experimental results on some well-known databases (including breastmnist, pneumoniamnist, colon-cancer, etc.) show the great potential of MSVM against classical discriminant analysis methods and SVM-related methods, and the codes can be available on https://www.scholat.com/laizhihui.

Synchronous papillary thyroid carcinoma and breast ductal carcinoma.

A 48-year-old woman was admitted to our hospital with a lump in her left breast. She was diagnosed with synchronous papillary thyroid carcinoma and breast ductal carcinoma. The patient underwent four cycles of neoadjuvant chemotherapy with epirubicin and cyclophosphamide, and one cycle of docetaxel. She then underwent left breast mastectomy and radical resection of thyroid cancer (total thyroidectomy and bilateral central group [levels VI and VII] lymph node dissection) at the same time. She was administered three cycles of chemotherapy with docetaxel and radiotherapy. The patient had no metastasis in the follow-up period. A literature search was performed to characterize the epidemiology, etiology, management, and prognosis of this condition. We speculate that hormone treatment could be a probable pathogenesis of synchronous breast and thyroid cancers.

IL-7 signaling imparts polyfunctionality and stemness potential to CD4(+) T cells.

The functional status of CD4(+) T cells is a critical determinant of antitumor immunity. Polyfunctional CD4(+) T cells possess the ability to concomitantly produce multiple Th1-type cytokines, exhibiting a functional attribute desirable for cancer immunotherapy. However, the mechanisms by which these cells are induced are neither defined nor it is clear if these cells can be used therapeutically to treat cancer. Here, we report that CD4(+) T cells exposed to exogenous IL-7 during antigenic stimulation can acquire a polyfunctional phenotype, characterized by their ability to simultaneously express IFNγ, IL-2, TNFα and granzyme B. This IL-7-driven polyfunctional phenotype was associated with increased histone acetylation in the promoters of the effector genes, indicative of increased chromatin accessibility. Moreover, forced expression of a constitutively active (CA) form of STAT5 recapitulated IL-7 in inducing CD4(+) T-cell polyfunctionality. Conversely, the expression of a dominant negative (DN) form of STAT5 abolished the ability of IL-7 to induce polyfunctional CD4(+) T cells. These in-vitro-generated polyfunctional CD4(+) T cells can traffic to tumor and expand intratumorally in response to immunization. Importantly, adoptive transfer of polyfunctional CD4(+) T cells following lymphodepletive chemotherapy was able to eradicate large established tumors. This beneficial outcome was associated with the occurrence of antigen epitope spreading, activation of the endogenous CD8(+) T cells and persistence of donor CD4(+) T cells exhibiting memory stem cell attributes. These findings indicate that IL-7 signaling can impart polyfunctionality and stemness potential to CD4(+) T cells, revealing a previously unknown property of IL-7 that can be exploited in adoptive T-cell immunotherapy.

All-trans retinoic acid enhances bystander effect of suicide gene therapy in the treatment of breast cancer.

All-trans retinoic acid (ATRA) has been shown to enhance the expression of connexin 43 (Cx43) and the bystander effect (BSE) in suicide gene therapy. These in turn improve effects of suicide gene therapies for several tumor types. However, whether ATRA can improve BSE remains unclear in suicide gene therapy for breast cancer. In the present study, MCF-7, human breast cancer cells were treated with ATRA in combination with a VEGFP-TK/CD gene suicide system developed by our group. We found that this combination enhances the efficiency of cell killing and apoptosis of breast cancer by strengthening the BSE in vitro. ATRA also promotes gap junction intercellular communication (GJIC) in MCF-7 cells by upregulation of the connexin 43 mRNA and protein in MCF-7 cells. These results indicate that enhancement of GJIC by ATRA in suicide gene system might serve as an attractive and cost-effective strategy of therapy for breast cancer cells.

CXCR7 functions in colon cancer cell survival and migration.

C-X-C chemokine receptor 7 (CXCR7) is a known promoter of tumor progression and metastasis; however, little is known about its role in colon cancer. The aim of the present study was to investigate the function of CXCR7 in human colon cancer cells. CXCR7 mRNA levels were examined in HT-29 and SW-480 human colon cancer cell lines using a quantitative polymerase chain reaction. CXCR7-knockdown was performed with small interfering RNA and lentiviral-mediated gene delivery. Immunofluorescence (IF) was conducted to examine CXCR7 expression and localization in colon cancer cells. Cell survival and migration were evaluated using MTT and migration assays, respectively. HT-29 cells expressed higher levels of CXCR7 mRNA and were therefore used in subsequent experiments. IF staining revealed that the CXCR7 protein was expressed on the cell membrane, and its expression decreased following CXCR7-short hairpin RNA lentiviral transfection. Lentiviral CXCR7-knockdown resulted in decreased cell survival and migration; however, MTT assays revealed that the lentiviral vector itself was cytotoxic. This cytotoxicity was indicated as the cell survival of the negative control group cells was significantly decreased compared with that of the blank control group cells (P<0.05). In conclusion, it is becoming increasingly evident that CXCR7 plays a role in colon cancer promotion, suggesting that CXCR7 is a promising biomarker for chemokine receptor-based drug development. Furthermore, the fact that CXCR7 is expressed on the membrane and not intracellularly makes it a prime target for drug-based intervention.

RPCA-Based Tumor Classification Using Gene Expression Data.

Microarray techniques have been used to delineate cancer groups or to identify candidate genes for cancer prognosis. As such problems can be viewed as classification ones, various classification methods have been applied to analyze or interpret gene expression data. In this paper, we propose a novel method based on robust principal component analysis (RPCA) to classify tumor samples of gene expression data. Firstly, RPCA is utilized to highlight the characteristic genes associated with a special biological process. Then, RPCA and RPCA+LDA (robust principal component analysis and linear discriminant analysis) are used to identify the features. Finally, support vector machine (SVM) is applied to classify the tumor samples of gene expression data based on the identified features. Experiments on seven data sets demonstrate that our methods are effective and feasible for tumor classification.

Quercetin reverses tamoxifen resistance in breast cancer cells.

PURPOSE: To investigate the effect of quercetin on the reversal of tamoxifen resistance in breast cancer cells, and explore the underlying mechanism. METHODS: We established a tamoxifen-resistant breast cancer cell line (MCF-7Ca/TAM-R), and exposed it to different concentrations of quercetin (experimental group 1: 10 µM, group 2: 25 µM, and group 3: 50µM). Each group was further subdivided into 2 subgroups: 1) simultaneous administration of quercetin and 4-hydroxytamoxifen (OHT); 2) sequential administration of quercetin (12-h induction) followed by OHT. No drug exposure and OHT alone were used as controls. We determined cell survival, apoptosis, and expression of ERα (estrogen receptor α) and Her-2 (human epidermal growth factor receptor 2). RESULTS: With increasing dosage of quercetin, significant decrease in proliferation and increase in apoptosis was observed. Low concentrations of quercetin (10 µM) had no effects. We found no significant difference between simultaneous and sequential mode of drug administration. Further, with increasing dosage of quercetin, we observed a gradual reduction in Her-2 expression and upregulation of ERα. Again, no difference in Her-2 and ERα protein levels between simultaneous and sequential drug administration was noticed. CONCLUSIONS: Proliferation inhibition and apoptosis in MCF-7Ca/TAM-R cells increase with increasing dosage of quercetin. This suggests that quercetin can reverse tamoxifen resistance in breast cancer cells. The underlying mechanism likely involves upregulation of ERα combined with downregulation of Her-2. However, this effect is independent of whether quercetin and tamoxifen are administered simultaneously or sequentially.

Role of CXC chemokine receptor type 7 in carcinogenesis and lymph node metastasis of colon cancer.

Upregulated expression of the CXC chemokine receptor type 7 (CXCR7) promotes breast, lung and prostate cancer progression and metastasis. However, the role of CXCR7 in colon cancer has not been determined. We hypothesized that increased CXCR7 expression may contribute to human colon cancer occurrence and progression. Reverse transcription quantitative polymerase chain reaction and western blot analysis were performed on 34 malignant and 18 normal colon tissue specimens. The specimens were obtained from 19 male and 15 female patients, with a mean age of 52 years (range, 34-79 years). Of the 34 patients, 20 had lymph node metastases. None of the patients had received adjuvant radiotherapy or chemotherapy prior to surgery. This study demonstrated that CXCR7 levels were significantly higher in colon tumors compared with those in normal colon tissue (P﹤0.01). In addition, lymph node metastatic colon tumors exhibited significantly higher CXCR7 expression compared with non-metastatic tumors (P﹤0.01); however, there were no differences in CXCR7 expression among distinct histopathological types (well-differentiated vs. moderately-to-poorly differentiated adenocarcinoma, P﹥0.01). Therefore, the evidence obtained from the present study supports involvement of the upregulated CXCR7 expression in colon tumorigenesis and lymph node metastasis.

Effects of an adenoviral vector containing a suicide gene fusion on growth characteristics of breast cancer cells.

The herpes simplex virus thymidine kinase/ganciclovir (HSV­TK/GCV) and the cytosine deaminase/5­fluorocytosine (CD/5­FC) systems have been widely applied in suicide gene therapy for cancer. Although suicide gene therapy has been successfully used in vitro and in vivo studies, the number of studies on the effects of recombinant adenoviruses (Ads) containing suicide genes on target cancer cells is limited. The aim of this study was to examine whether recombinant Ads containing the CD/TK fusion gene affect cell proliferation of breast cancer cells in vitro. In the present study, we explored the use of a recombinant adenoviral vector to deliver the CD/TK fusion gene to the breast cancer cell line MCF­7. We found that the recombinant adenoviral vector efficiently infected MCF­7 cells. Western blot analysis revealed that CD and TK proteins are expressed in the infected cells. The infected breast cancer cells did not show any significant changes in morphology, ultrastructure, cell growth, and cell­cycle distribution compared to the uninfected cells. This study revealed that the Ad­vascular endothelial growth factor promoter (VEGFp)­CD/TK vector is non­toxic to MCF­7 cells at the appropriate titer. Our results indicate that it is feasible to use a recombinant adenoviral vector containing the CD/TK fusion gene in suicide gene therapy to target breast cancer cells.

Metformin inhibits proliferation and promotes apoptosis of HER2 positive breast cancer cells by downregulating HSP90.

PURPOSE: To investigate the effects and the possible molecular mechanisms of metformin on HER2 positive breast cancer cells. METHODS: SK-BR-3 HER2 positive breast cancer cells were treated with different concentrations of metformin. The growth inhibitory rate of the cells was calculated by MTT assay, apoptosis was detected by flow cytometry, and the expression level of heat shock protein 90 (HSP90) was performed by Western blot analysis. A control group consisted of cells treated with PBS. RESULTS: With increased concentrations of metformin, cell growth inhibitory rates increased. The growth inhibitory rates with 0.5 mM, 2mM or 8mM metformin were significantly higher compared with the control group (p<0.05). Apoptosis in the metformin treated cells was also significantly higher compared with the control group (p=0.003). The expression level of HSP90 in the metformin group was significantly lower than that in the control group. CONCLUSION: Metformin can inhibit the proliferation and promote apoptosis of HER2 positive breast cancer cells,which is maybe related to inhibition of HSP90.

[Selective cytotoxic effect of lentivirus-mediated double suicide gene transfer on human gastric adneocarcinoma cells].

OBJECTIVE: To study the selective cytotoxic effect of lentivirus-mediated double suicide gene (CD/TK) against human gastric carcinoma cells SGC-7901 in vitro. METHODS: SGC-7901 cells were infected with FGW-KDRP-CD/TK vector and the infection efficiency was observed under a fluorescence microscope. The morphological changes of the infected cells were observed by Giemsa staining. Flow cytometry (FCM) was employed for cell cycle analysis, and the expression of CD/TK was detected by RT-PCR. The infected cells were then treated with the prodrugs ganciclovir (GCV) and/or 5-fluorocytosine (5-FC) at different concentrations, and the cytotoxic effects were evaluated using MTT method. RESULTS: The infection efficiency of the lentiviral vector in SGC-7901 cells increased with the titer of the virus, which produced no significant effect on the cancer cell morphology in vitro or on the percentages of G0-G1, G2-M and S phase cells (P>0.05). RT-PCR demonstrated the expression of CD/TK gene in SGC-7901 cells infected by FGW-KDRP-CD/TK. The infected cells were highly sensitive to the prodrugs with a dose-dependent cytotoxic effect within a specific concentration range of the drugs, whereas the non-infected cells were not sensitive to the prodrugs. Combined use of the two prodrugs produced an obviously stronger inhibitory effect than either of the them (P<0.05). When combined, GCV and 5-FC at the concentration of 0.1+40, 1+80, 10+160, and 100+320 mg/L demonstrated a synergetic effect with a CDI<1. CONCLUSION: Lentivirus-mediated CD/TK fusion gene system can selectively kill gastric cancer cells, and the two prodrugs show a synergistic cytotoxic effect.

Vitreous cryopreservation of nanofibrous tissue-engineered constructs generated using mesenchymal stromal cells.

Development of an effective preservation strategy to fulfill off-the-shelf availability of tissue-engineered constructs (TECs) is demanded for realizing their clinical potential. In this study, the feasibility of vitrification, ice-free cryopreservation, for precultured ready-to-use TECs was evaluated. To prepare the TECs, bone marrow-derived porcine mesenchymal stromal cells (MSCs) were seeded in polycaprolactone-gelatin nanofibrous scaffolds and cultured for 3 weeks before vitrification treatment. The vitrification strategy developed, which involved exposure of the TECs to low concentrations of cryoprotectants followed by a vitrification solution and sterile packaging in a pouch with its subsequent immersion directly into liquid nitrogen, was accomplished within 11min. Stepwise removal of cryoprotectants, after warming in a 38 degrees C water bath, enabled rapid restoration of the TECs. Vitrification did not impair microstructure of the scaffold or cell viability. No significant differences were found between the vitrified and control TECs in cellular metabolic activity and proliferation on matched days and in the trends during 5 weeks of continuous culture postvitrification. Osteogenic differentiation ability in vitrified and control groups was similar. In conclusion, we have developed a time- and cost-efficient cryopreservation method that maintains integrity of the TECs while preserving MSCs viability and metabolic activity, and their ability to differentiate.

[A double suicide gene system driven by KDR promoter selectively kills human hepatic carcinoma cells and human umbilical vein endothelial cells].

OBJECTIVE: To study the selective killing effects of adenovirus (Ad)-mediated double suicide gene system driven by KDR promoter (KDR-CdglyTK) on the human hepatic carcinoma cells and human umbilical vein endothelial cells (HUVECs). METHODS: KDR-expressing BEL-7402 and HUVECs and HepG2 cells that did not express KDR were infected by KDR-CdglyTK, and the infection efficiency and the expression of CdglyTK in the cells was detected by RT-PCR. The infected cells were treated with the the prodrugs 5-FC and GCV at different concentrations, and the cell-killing effects and bystander effects were evaluated by MTT method. RESULTS: At the multiplicity of infection (MOI) of 100, the recombinant AdKDR-CDglyTK showed similar infection efficiency in the 3 cell lines. RT-PCR demonstrated CDglyTK expression in the recombinant adenovirus and the 3 infected cell lines. BEL-7402 and HUVECs infected by the KDR-CdglyTK, but not the HepG2 cells, were highly sensitive to the prodrugs (P<0.001). Bystander effects of the double suicide gene system were observed in the coculture of the infected and non-infected BEL-7402 and HUVECs. CONCLUSION: The double suicide gene system driven by KDR promoter has specific killing effect on KDR-expressing hepatocellular carcinoma cells and HUVECs.

Cryopreservation of alginate-fibrin beads involving bone marrow derived mesenchymal stromal cells by vitrification.

Application of cell--biomaterial systems in regenerative medicine can be facilitated by their successful low temperature preservation. Vitrification, which avoids ice crystal formation by amorphous solidification, is an emerging approach to cryopreservation. Developing vitrification strategy, effective cryopreservation of alginate-fibrin beads with porcine mesenchymal stromal cells has been achieved in this study. The cell-biomaterial constructs were pre-cultured for 20 days before cryopreservation, allowing for cell proliferation and construct stabilization. Ethylene glycol (EG) was employed as the basic cryoprotectant for two equilibration solutions. Successful cryopreservation of the constructs was achieved using vitrification solution composed of penetrating (EG MW 62 Da) and non-penetrating (sucrose MW 342 Da) cryoprotectants. Stepwise procedure of introduction to and removal of cryoprotectants was brief; direct plunging into liquid nitrogen was applied. Cell viability, evaluated by combining live/death staining and confocal laser microscopy, was similar for both control and vitrified cells in the beads. No detectable damage of microstructure of cryopreserved beads was found as shown by scanning electron microscopy. Both osteogenically induced control and vitrified cells in the constructs were equally capable of mineral production and deposition. There was no statistically significant difference in metabolic activity and proliferation between both groups during the entire culture period. Our study leads to the conclusion that the developed cryopreservation protocol allowed to maintain the integrity of the beads while preserving the ability of the pig bone marrow derived mesenchymal stromal cells to proliferate and subsequently differentiate; demonstrating that vitrification is a promising approach for cryopreservation of "ready-to-use" cell-biomaterial constructs.

[Adenovirus-mediated double suicide gene selectively kills breast cancer MCF-7 cells in vitro].

OBJECTIVE: To evaluate the effect of adenovirus-mediated double suicide gene (CD/TK) for selective killing of breast cancer cells. METHODS: Vascular endothelial growth factor (VEGF)-expressing MCF-7 cells and normal human mammary epithelial cells that did not express VEGF were infected with the adenovirus containing VEGFP-CD/TK-GFP genes. CD/TK gene expression in the infected cells was detected by RT-PCR. After treatment of the infected cells with GCV and/or 5-FC, the cell growth status was evaluated using MTT assay, and the cell cycle changes were detected with flow cytometry. In nude mice bearing human breast cancer, the recombinant adenovirus vector was injected directly into the tumor followed by intraperitoneal injection of the prodrugs GCV and/or 5-FC, and the subsequent tumor growth was observed. RESULTS: The recombinant adenovirus achieved similar infection rates in MCF-7 and human mammary epithelial cells, and the rates increased gradually with the multiplicity of infection (MOI) of the virus. RT-PCR demonstrated the presence of CD/TK gene product in infected MCF-7 cells, but not in the infected mammary epithelial cells. The infected MCF-7 cells, but not the mammary epithelial cells, were highly sensitive to the pro-drugs. The CD/TK fusion gene system showed significantly greater efficiency than either of the single suicide gene in killing the target cells (P<0.01). At the MOI of 100, treatment of the infected cells with the pro-drugs resulted in increased cell percentage in G(0)-G(1) phase and decreased percentage in S phase. In nude mice bearing MCF-7 cell-derived subcutaneous tumor, treatment with the double suicide gene system significantly inhibited the tumor growth, showing much stronger effect than either of the single suicide gene (P<0.01). CONCLUSION: The adenovirus-mediated CD/TK double suicide gene driven by VEGF promoter combined with GCV and 5-FC treatment can be an effective therapy against experimental breast cancer, and produces much greater efficacy than the single suicide gene CD/TK combined with GCV or 5-FC.

[Experimental study on artesunate inducing apoptosis of hypertrophic scar fibroblasts].

OBJECTIVE: To study the effect and mechanism of the apoptosis of hypertrophic scar fibroblasts (HSF) induced by artesunate (Art). METHODS: HSFs were isolated and cultured from human earlobe scars by the tissue adherence method. The 3th to 5th generation cells were harvested and divided into two groups. HSF was cultured with normal medium in control group and with medium containing 60, 120 and 240 mg/L (5 ml) Art in experimental group. Apoptosis and cell cycle were identified by light microscopy, electronmicroscopy and flow cytometry. Then, HSF was cultured with normal medium in control group and with medium containing 30, 60 and 120 mg/L Art in experimental group. The changes of intracellular calcium concentration were observed. RESULTS: The primary HSF was fusiform in shape and adherent. The vimentin positive expression was analyzed by immunocytochemistry. Art could induce apoptosis of HSF in the range of 60-240 mg/L under inverted microscope. The effect was dose- and time-dependent. Clumping of nuclear chromatin showed margination in the experimental group. And the disaggregation of the nucleolus were observed under electronmicroscopy. There were significant differences in the proportion of HSF apoptosis and HSF at G0-G1, S, G2-M stages between the two groups (P < 0.05). Apoptotic peak was shown in experimental group by flow cytometry. The peak became more evident as Art concentration increased. The intracellular calcium concentration elevated markedly in HSF with 30-120 mg/L Art treatment for 24 hours, showing significant differences between the two groups (P < 0.05). CONCLUSION: The Art facilitates HSF cells apoptosis in vitro by the change of cell cycle. It is suggested that intracellular calcium variation may be one of the mechanisms of HSF apoptosis induced by Art.

[Preliminary effect of VEGF promoter-driven recombinant adenovirus containing double suicide genes on apoptosis of human gastric carcinoma cells].

OBJECTIVE: To study the effect of the adenovirus containing CD/TK fusion gene controlled by the human vascular endothelial growth factor (VEGF) promoter on apoptosis of human gastric carcinoma cells SGC-7901. METHODS: VEGF-expressing SGC-7901 cells were infected by the recombinant adenovirus Ad-VEGFP-CD/TK, and the infection efficiencies were observed with fluorescence microscopy. The toxic effect and intracellular calcium concentration induced by 5-fluorocytosine (5-FC) and ganciclovic (GCV) were determined by light microscopy, electron microscopy and flow cytometry. RESULTS: The transfection efficiency of the recombinant adenovirus in SGC-7901 cells increased with the viral titer. At the multiplicity of infection (MOI) of 100, 5-FC and GCV could induce apoptosis of SGC-7901 cells within a given dose range in a dose- and time-dependent manner, and apoptotic changes of the cells were observed with electron microscopy. Apoptotic peak was also detected by flow cytometry. Cell cycle analysis revealed increased cell percentage in G(0)-G(1) phase and decreased percentage of cells in G(2)-M and S phases in response to treatment with the pro-drugs, which also induced marked elevation of intracellular calcium concentration in the infected cells. CONCLUSIONS: CD/TK fusion gene system driven by VECF promoter selectively induces apoptosis of VEGF-expressing SGC-7901 cells, the action of which is probably mediated by intracellular calcium variation.