The tumor-selective over-expression of the human Hsp70 gene is attributed to the aberrant controls at both initiation and elongation levels of transcription

DNA Origami Frameworks Enabled Self-Protective siRNA Delivery for Dual Enhancement of Chemo-Photothermal Combination Therapy

Although chemotherapy and photothermal therapy are widely used to combat cancer, their efficacy is often limited by multidrug resistance. Small interfering RNAs (siRNAs) have ability to suppress the expression of target genes, which has been extensively employed for combating the multidrug resistance to chemodrugs and hyperthermia in cancer therapy. However, efficient delivery of siRNAs along with chemo-photothermal agents in vivo is still an enormous challenge. Herein, octahedral DNA origami frameworks (OctDOFs) are constructed as a nanovehicle for precise organization and orchestrated delivery of siRNAs, chemodrugs (doxorubicin, Dox), and photothermal agents (gold nanorods, AuNRs) in combinatorial treatment of cancer. The inner cavity of the rigid OctDOFs structure is able to shield the encapsulated siRNAs during transportation by sterically hindering RNase degradation and protein binding, thus achieving effective downregulation of connective tissue growth factor (CTGF) and heat shock protein 72 (HSP72) for dual sensitization of cancer cells to chemodrugs and hyperthermia. By amplifying chemo-photothermal therapeutic potency with siRNAs, the proposed OctDOFs exhibited superior cytotoxicity and tumor inhibition efficacy in vitro and in vivo. This nanovehicle creates a promising siRNA delivery platform for precise medication and combination therapy.

Molecular chaperones in the acquisition of cancer cell chemoresistance with mutated TP53 and MDM2 up-regulation

Utilizing the TCGA PANCAN12 dataset we discovered that cancer patients with mutations in TP53 tumor suppressor and overexpression of MDM2 oncogene exhibited decreased survival post treatment. Interestingly, in the case of breast cancer patients, this phenomenon correlated with high expression level of several molecular chaperones belonging to the HSPA, DNAJB and HSPC families. To verify the hypothesis that such a genetic background may promote chaperone-mediated chemoresistance, we employed breast and lung cancer cell lines that constitutively overexpressed heat shock proteins and have shown that HSPA1A/HSP70 and DNAJB1/HSP40 facilitated the binding of mutated p53 to the TAp73α protein. This chaperone-mediated mutated p53–TAp73α complex induced chemoresistance to DNA damaging reagents, like Cisplatin, Doxorubicin, Etoposide or Camptothecin. Importantly, when the MDM2 oncogene was overexpressed, heat shock proteins were displaced and a stable multiprotein complex comprising of mutated p53-TAp73α-MDM2 was formed, additionally amplifying cancer cells chemoresistance. Our findings demonstrate that molecular chaperones aid cancer cells in surviving the cytotoxic effect of chemotherapeutics and may have therapeutic implications.

Heat shock factor 1 accelerates hepatocellular carcinoma development by activating nuclear factor-κB/mitogen-activated protein kinase

Heat shock factor 1 (HSF1), a major transactivator of stress responses, has been implicated in carcinogenesis in various organs. However, little is known about the biological functions of HSF1 in the development of hepatocellular carcinoma (HCC). To clarify the functional role of HSF1 in HCC, we established HSF1-knockdown (HSF1 KD) KYN2 HCC cells by stably expressing either small hairpin RNA (shRNA) against HSF1 (i.e. HSF1 KD) or control shRNA (HSF1 control). Tumorigenicity was significantly reduced in orthotopic mice with HSF1 KD cells compared with those with HSF1 control cells. Reduced tumorigenesis in HSF1 KD cells appeared attributable to increased apoptosis and decreased proliferation. Tumor necrosis factor-α-induced apoptosis was increased in HSF1 KD cells and HSF1(-/-) mouse hepatocytes compared with controls. Decreased expression of IκB kinase γ, a positive regulator of nuclear factor-κB, was also observed in HSF1 KD cells and HSF1(-/-) mouse hepatocytes. Furthermore, expression of bcl-2-associated athanogene domain 3 (BAG3) was dramatically reduced in HSF1 KD cells and HSF1(-/-) mouse hepatocytes. We also found that epidermal growth factor-stimulated mitogen-activated protein kinase signaling was impaired in HSF1 KD cells. Clinicopathological analysis demonstrated frequent overexpression of HSF1 in human HCCs. Significant correlations between HSF1 and BAG3 protein levels and prognosis were also observed. In summary, these results identify a mechanistic link between HSF1 and liver tumorigenesis and may provide as a potential molecular target for the development of anti-HCC therapies.

Selective induction of tumor cell apoptosis by a novel P450-mediated reactive oxygen species (ROS) inducer methyl 3-(4-nitrophenyl) propiolate

Induction of tumor cell apoptosis has been recognized as a valid anticancer strategy. However, therapeutic selectivity between tumor and normal cells has always been a challenge. Here, we report a novel anti-cancer compound methyl 3-(4-nitrophenyl) propiolate (NPP) preferentially induces apoptosis in tumor cells through P450-catalyzed reactive oxygen species (ROS) production. A compound sensitivity study on multiple cell lines shows that tumor cells with high basal ROS levels, low antioxidant capacities, and p53 mutations are especially sensitive to NPP. Knockdown of p53 sensitized non-transformed cells to NPP-induced cell death. Additionally, by comparing NPP with other ROS inducers, we show that the susceptibility of tumor cells to the ROS-induced cell death is influenced by the mode, amount, duration, and perhaps location of ROS production. Our studies not only discovered a unique anticancer drug candidate but also shed new light on the understanding of ROS generation and function and the potential application of a ROS-promoting strategy in cancer treatment.

Heat shock proteins in oncology: diagnostic biomarkers or therapeutic targets?

Heat shock proteins (HSP) are a family of proteins induced in cells exposed to different insults. This induction of HSPs allows cells to survive stress conditions. Mammalian HSPs have been classified into six families according to their molecular size: HSP100, HSP90, HSP70, HSP60, HSP40 and small HSPs (15 to 30kDa) including HSP27. These proteins act as molecular chaperones either helping in the refolding of misfolded proteins or assisting in their elimination if they become irreversibly damaged. In recent years, proteomic studies have characterized several different HSPs in various tumor types which may be putative clinical biomarkers or molecular targets for cancer therapy. This has led to the development of a series of molecules capable of inhibiting HSPs. Numerous studies speculated that over-expression of HSP is in part responsible for resistance to many anti-tumor agents and chemotherapeutics. Hence, from a pharmacological point of view, the co-administration of HSP inhibitors together with other anti-tumor agents is of major importance in overcoming therapeutic resistance. In this review, we provide an overview of the current status of HSPs in autoimmune, cardiovascular, and neurodegenerative diseases with special emphasis on cancer.

Global gene expression profiling and validation in esophageal squamous cell carcinoma and its association with clinical phenotypes

PURPOSE

Esophageal squamous cell carcinoma (ESCC) is an aggressive tumor with poor prognosis. Understanding molecular changes in ESCC will enable identification of molecular subtypes and provide potential targets for early detection and therapy.

EXPERIMENTAL DESIGN

We followed up a previous array study with additional discovery and confirmatory studies in new ESCC cases by using alternative methods. We profiled global gene expression for discovery and confirmation, and validated selected dysregulated genes with additional RNA and protein studies.

RESULTS

A total of 159 genes showed differences with extreme statistical significance (P < E-15) and 2-fold differences or more in magnitude (tumor/normal RNA expression ratio, N = 53 cases), including 116 upregulated and 43 downregulated genes. Of 41 genes dysregulated in our prior array study, all but one showed the same fold change directional pattern in new array studies, including 29 with 2-fold changes or more. Alternative RNA expression methods validated array results: more than two thirds of 51 new cases examined by real-time PCR (RT-PCR) showed 2-fold differences or more for all seven genes assessed. Immunohistochemical protein expression results in 275 cases which were concordant with RNA for five of six genes.

CONCLUSION

We identified an expanded panel of genes dysregulated in ESCC and confirmed previously identified differentially expressed genes. Microarray-based gene expression results were confirmed by RT-PCR and protein expression studies. These dysregulated genes will facilitate molecular categorization of tumor subtypes and identification of their risk factors, and serve as potential targets for early detection, outcome prediction, and therapy.

Heat-shock transcription factor HSF1 has a critical role in human epidermal growth factor receptor-2-induced cellular transformation and tumorigenesis

The heat shock transcription factor HSF1 was recently demonstrated to play a key role in the development of tumors associated with activation of Ras or inactivation of p53. Here we show that HSF1 is required for cell transformation and tumorigenesis induced by HER2 oncogene responsible for aggressive breast tumors. Upon expression of HER2, untransformed human mammary epithelial cells MCF-10A underwent neoplastic transformation, formed foci in culture and tumors in nude mouse xenografts. However, expression of HER2 in MCF-10A cells with knockdown of HSF1 did not cause either foci formation or tumor growth in xenografts. The anti-tumorigenic effect of downregulation of HSF1 was associated with HER2-induced accumulation of the CDK inhibitor p21 and decrease of the mitotic regulator survivin, which resulted in growth inhibition and cell senescence. In fact, either knockout of p21 or overexpression of survivin alleviated these effects of HSF1 knockdown. Proliferation of certain human HER2-postitive breast cancer lines also requires HSF1, since its knockdown led to upregulation of p21 and/or drop of survivin, precipitating growth arrest. Similar effects were observed with a small molecular weight inhibitor of the heat shock response NZ28. Effects of HSF1 knockdown on growth arrest and senescence of HER2-expressing cells were associated with downregulation of Hsp72 and Hsp27. Therefore, HSF1 is critical for proliferation of HER2-expressing cells, most likely since it maintains levels of HSPs, which in turn control regulators of senescence p21 and survivin.

Transcription of the putative tumor suppressor gene HCCS1 requires binding of ETS-2 to its consensus near the transcription start site

The hepatocellular carcinoma suppressor 1 (HCCS1) gene was identified by both positional cloning from a predominant region of loss of heterozygosity (17p13.3) in liver cancer and by functional screening for genes affecting cell proliferation in large-scale transfection assays. Its overexpression results in inhibition of cell proliferation in cell culture and tumor growth in nude mice. To understand its transcription regulation, the promoter architecture has been dissected in detail. The major start of transcription was mapped by primer extension to a C residue, 177 nucleotides upstream of the ATG codon. By assessing the promoter activity of a set of linker-scanning mutants of the minimal promoter (-60 to +148 region) in a transient transfection assay, we found that the +1 to + 40 region is critical to HCCS1 gene transcription, containing binding sites for transcription factors NF-kappaB (-21 to +7 and +40 to +26), p53 (+29 to +9) and ETS (+4 to +20 and +23 to +39). Biochemical and molecular analyses revealed that the ETS transcription factors ETS-2 and Elf-1 bind to the two ETS sites in situ and contribute significantly to the transcriptionally active state of the HCCS1 gene, while NF-kappaB, p53 and two other members of the ETS family (ETS-1 and NERF2) appear to play little role. Our observations provide insight into the mechanistic aspects of HCCS1 transcription regulation.

Targeting the heat shock factor 1 by RNA interference: a potent tool to enhance hyperthermochemotherapy efficacy in cervical cancer

Carcinoma of the uterine cervix is one of the highest causes of mortality in female cancer patients worldwide, and improved treatment options for this type of malignancy are highly needed. Local hyperthermia has been successfully used in combination with systemic administration of cisplatin-based chemotherapy in phase I/II clinical studies. Heat-induced expression of cytoprotective and antiapoptotic heat shock proteins (HSP) is a known complication of hyperthermia, resulting in thermotolerance and chemoresistance and hindering the efficacy of the combination therapy. Heat shock transcription factor 1 (HSF1) is the master regulator of heat-induced HSP expression. In the present report, we used small interfering RNA (siRNA) to silence HSF1 and to examine the effect of HSF1 loss of function on the response to hyperthermia and cisplatin-based chemotherapy in HeLa cervical carcinoma. We have identified the 322-nucleotide to 340-nucleotide HSF1 sequence as an ideal target for siRNA-mediated HSF1 silencing, have created a pSUPER-HSF1 vector able to potently suppress the HSF1 gene, and have generated for the first time human cancer cell lines with stable loss of HSF1 function. We report that, although it surprisingly does not affect cancer cell sensitivity to cisplatin or elevated temperatures up to 43 degrees C when administered separately, loss of HSF1 function causes a dramatic increase in sensitivity to hyperthermochemotherapy, leading to massive (>95%) apoptosis of cancer cells. These findings indicate that disruption of HSF1-induced cytoprotection during hyperthermochemotherapy may represent a powerful strategy to selectively amplify the damage in cancer cells and identify HSF1 as a promising therapeutic target in cervical carcinoma.

The altered DNA methylation pattern and its implications in liver cancer

DNA methylation is the most intensively studied epigenetic phenomenon, disturbances of which result in changes in gene transcription, thus exerting drastic imparts onto biological behaviors of cancer. Both the global demethylation and the local hypermethylation have been widely reported in all types of tumors, providing both challenges and opportunities for a better understanding and eventually controlling of the malignance. However, we are still in the very early stage of information accumulation concerning the tumor associated changes in DNA methylation pattern. A number of excellent recent reviews have covered this issue in depth. Therefore, this review will summarize our recent data on DNA methylation profiling in cancers. Perspectives for the future direction in this dynamic and exciting field will also be given.

A novel protein-DNA interaction involved with the CpG dinucleotide at -30 upstream is linked to the DNA methylation mediated transcription silencing of the MAGE-A1 gene

To understand the DNA-methylation mediated gene silencing mechanisms, we analyzed in cell culture of the promoter function of the MAGE-A1 gene, which is frequently demethylated and over-expressed in human hepatocellular carcinoma. We have established the correlation of the DNA methylation of the promoter CpG island with expression status of this gene in a panel of the established liver cancer cell lines. The crucial CpG dinucleotide(s) within the minimal promoter subjected to the control mediated by DNA methylation with profound biological functions was also delineated. Furthermore, a novel sequence-specific DNA-protein interaction at the -30 CpG dinucleotide upstream of the gene was found having a vital part to play in the DNA methylation mediated transcription silencing of the MAGE-A1 gene. Our results would not only provide new insights into the DNA methylation mediated mechanisms over transcription of the MAGE-A1 gene, but also pave the way for further defining the cross-talk among DNA methylation, histone modification and chromatin remodeling in detail.

Methylation profile of the promoter CpG islands of 14 “drug-resistance” genes in hepatocellular carcinoma

AIM: To establish the DNA methylation patterns of the promoter CpG islands of 14 “drug-resistance” genes in hepatocellular carcinoma (HCC).

METHODS: The methylation specific polymerase chain reaction in conjunction with sequencing verification was used to establish the methylation patterns of the 14 genes in the liver tissues of four healthy liver donors, as well as tumor and the paired non-cancerous tissues of 30 HCC patients.

RESULTS: While 11 genes (ATP-binding cassette, sub-family G (WHITE), member 2(ABCG2), activating transcription factor (ATF2), beta-2-microglobulin (B2M), deoxycytidine kinase (DCK), occludin (OCLN), v-raf-1 murine leukemia viral oncogene homolog (RAF1), ralA binding protein 1 (RALBP1), splicing factor (45 kD) (SPF45), S-phase kinase-associated protein 2 (p45) (SKP2), tumor protein p53 (Li-Fraumeni syndrome) (TP53) and topoisomerase (DNA) II beta (TOP2B)) maintained the unmethylated patterns, three genes displayed to various extents the hypermethylation state in tumor tissues in comparison with the normal counterparts. The catalase (CAT) was hypermethylated in tumor and the neighboring non-cancerous tissue of one case (3.3%). Both glutathione S-transferase pi (GSTpi) (80%, 24/30 in tumor and 56.7%, 17/30 in the paired non-cancerous tissues) and cystic fibrosis transmembrane conductance regulator, ATP-binding cassette (sub-family C, member 7) (CFTR) (77%, 23/30 in tumor and 50%, 15/30 in the paired non-cancerous tissues) genes were prevalently hypermethylated in HCC as well as their neighboring non-cancerous tissues. No significant difference in the hypermethylation occurrence was observed between the HCC and its neighboring non-cancerous tissues.

CONCLUSION: Hypermethylation of promoter CpG islands of both CFTR and GSTpi genes occurs prevalently in HCC, which may correlate with the low expression of these two genes at the mRNA level and has the profound etiological and clinical implications. It is likely to be specific to the early phase of HCC carcinogenesis.

Methylation profile of the promoter CpG islands of 14 "drug-resistance" genes in hepatocellular carcinoma

AIM

To establish the DNA methylation patterns of the promoter CpG islands of 14 "drug-resistance" genes in hepatocellular carcinoma (HCC).

METHODS

The methylation specific polymerase chain reaction in conjunction with sequencing verification was used to establish the methylation patterns of the 14 genes in the liver tissues of four healthy liver donors, as well as tumor and the paired non-cancerous tissues of 30 HCC patients.

RESULTS

While 11 genes (ATP-binding cassette, sub-family G (WHITE), member 2(ABCG2), activating transcription factor (ATF2), beta-2-microglobulin (B2M), deoxycytidine kinase (DCK), occludin (OCLN), v-raf-1 murine leukemia viral oncogene homolog (RAF1), ralA binding protein 1 (RALBP1), splicing factor (45 kD) (SPF45), S-phase kinase-associated protein 2 (p45) (SKP2), tumor protein p53 (Li-Fraumeni syndrome) (TP53) and topoisomerase (DNA) II beta (TOP2B)) maintained the unmethylated patterns, three genes displayed to various extents the hypermethylation state in tumor tissues in comparison with the normal counterparts. The catalase (CAT) was hypermethylated in tumor and the neighboring non-cancerous tissue of one case (3.3%). Both glutathione S-transferase pi (GSTpi) (80%, 24/30 in tumor and 56.7%, 17/30 in the paired non-cancerous tissues) and cystic fibrosis transmembrane conductance regulator, ATP-binding cassette (sub-family C, member 7) (CFTR) (77%, 23/30 in tumor and 50%, 15/30 in the paired non-cancerous tissues) genes were prevalently hypermethylated in HCC as well as their neighboring non-cancerous tissues. No significant difference in the hypermethylation occurrence was observed between the HCC and its neighboring non-cancerous tissues.

CONCLUSION

Hypermethylation of promoter CpG islands of both CFTR and GSTpi genes occurs prevalently in HCC, which may correlate with the low expression of these two genes at the mRNA level and has the profound etiological and clinical implications. It is likely to be specific to the early phase of HCC carcinogenesis.