DNA damage response pathways and cell cycle checkpoints in colorectal cancer: current concepts and future perspectives for targeted treatment

Uracil- and Pyridine-Containing HDAC Inhibitors Displayed Cytotoxicity in Colorectal and Glioblastoma Cancer Stem Cells

Cancer stem cells (CSCs) are a niche of highly tumorigenic cells featuring self-renewal, activation of pluripotency genes, multidrug resistance, and ability to cause cancer relapse. Seven HDACi (1-7), showing either hydroxamate or 2'-aminoanilide function, were tested in colorectal cancer (CRC) and glioblastoma multiforme (GBM) CSCs to determine their effects on cell proliferation, H3 acetylation levels and in-cell HDAC activity. Two uracil-based hydroxamates, 5 and 6, which differ in substitution at C5 and C6 positions of the pyrimidine ring, exhibited the greatest cytotoxicity in GBM (5) and CRC (6) CSCs, followed by the pyridine-hydroxamate 2, with 2- to 6-fold higher potency than the positive control SAHA. Finally, increased H3 acetylation as well as HDAC inhibition directly in cells by selected 2'-aminoanilide 4 and hydroxamate 5 confirmed target engagement. Further investigation will be conducted into the broad-spectrum anticancer properties of the most potent derivatives and their effects in combination with approved, conventional anticancer drugs.

USP25 Elevates SHLD2-Mediated DNA Double-Strand Break Repair and Regulates Chemoresponse in Cancer

DNA damage plays a significant role in the tumorigenesis and progression of the disease. Abnormal DNA repair affects the therapy and prognosis of cancer. In this study, it is demonstrated that the deubiquitinase USP25 promotes non-homologous end joining (NHEJ), which in turn contributes to chemoresistance in cancer. It is shown that USP25 deubiquitinates SHLD2 at the K64 site, which enhances its binding with REV7 and promotes NHEJ. Furthermore, USP25 deficiency impairs NHEJ-mediated DNA repair and reduces class switch recombination (CSR) in USP25-deficient mice. USP25 is overexpressed in a subset of colon cancers. Depletion of USP25 sensitizes colon cancer cells to IR, 5-Fu, and cisplatin. TRIM25 is also identified, an E3 ligase, as the enzyme responsible for degrading USP25. Downregulation of TRIM25 leads to an increase in USP25 levels, which in turn induces chemoresistance in colon cancer cells. Finally, a peptide that disrupts the USP25-SHLD2 interaction is successfully identified, impairing NHEJ and increasing sensitivity to chemotherapy in PDX model. Overall, these findings reveal USP25 as a critical effector of SHLD2 in regulating the NHEJ repair pathway and suggest its potential as a therapeutic target for cancer therapy.

PARP1 bound to XRCC2 promotes tumor progression in colorectal cancer

BACKGROUND

By complexing poly (ADP-ribose) (PAR) in reaction to broke strand, PAR polymerase1 (PARP1) acts as the key enzyme participated in DNA repair. However, recent studies suggest that unrepaired DNA breaks results in persistent PARP1 activation, which leads to a progressively reduce in hexokinase1 (HK1) activity and cell death. PARP-1 is TCF-4/β-A novel co activator of gene transactivation induced by catenin may play a role in the development of colorectal cancer. The molecular mechanism of PARP1 remains elusive.

METHODS

212 colorectal cancer (CRC) patients who had the operation at our hospital were recruited. PARP1 expression was evaluated by immunohistochemistry. Stable CRC cell lines with low or high PARP1 expression were constructed. Survival analysis was computed based on PARP1 expression. The cell proliferation was tested by CCK-8 and Colony formation assay. The interaction of PARP1 and XRCC2 was detected by immunoprecipitation (IP) analysis.

RESULTS

Compared with matching adjacent noncancerous tissue, PARP1 was upregulated in CRC tissue which was correlated with the degree of differentiation, TNM stage, depth of invasion, metastasis, and survival. In addition, after constructing CRC stable cell lines with abnormal expression of PARP1, we found that overexpression of PARP1 promoted proliferation, and demonstrated the interaction between PARP1 and XRCC2 in CRC cells through immunoprecipitation (IP) analysis. Moreover, the inhibitor of XRCC2 can suppress the in vitro proliferation arousing by upregulation of PARP1.

CONCLUSIONS

PARP1 was upregulated in CRC cells and promoted cell proliferation. Furthermore, the expression status of PARP1 was significantly correlated with some clinicopathological features and 5-year survival.

Effect of Raltitrexed on ECA109 Cellular Radiosensitivity and its Mechanism in Esophageal Cancer

BACKGROUND

To investigate the effect of raltitrexed + X-ray irradiation on esophageal cancer ECA109 cells and analyze the potential action mechanism.

METHODS

The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to analyze the inhibitory effect of raltitrexed on cell proliferation. The effect of raltitrexed on radiosensitivity was studied through a clone-forming experiment. The scratch assay and invasion test were performed to understand the cell migration and invasion abilities. The apoptosis rate change was measured using a flow cytometer, and Western Blotting was used to determine the expression of B cell lymphoma-2 (Bcl-2) and Bcl2-associated X protein (Bax) in each group.

RESULTS

Raltitrexed significantly inhibited ECA109 proliferation in a time-dose-dependent manner; there were significant differences among different concentrations and times of action. The results of the clone-forming experiment showed a sensitization enhancement ratio of 1.65, and this demonstrated a radiosensitization effect. After the combination of raltitrexed with X-ray, the cell migration distance was shortened, and the number of cells penetrating the membrane was reduced.

CONCLUSION

Raltitrexed can inhibit the growth of esophageal cancer ECA109 cells and has a radiosensitization effect.

Notch receptor/ligand diversity: contribution to colorectal cancer stem cell heterogeneity

Cancer cell heterogeneity is a key contributor to therapeutic failure and post-treatment recurrence. Targeting cell subpopulations responsible for chemoresistance and recurrence seems to be an attractive approach to improve treatment outcome in cancer patients. However, this remains challenging due to the complexity and incomplete characterization of tumor cell subpopulations. The heterogeneity of cells exhibiting stemness-related features, such as self-renewal and chemoresistance, fuels this complexity. Notch signaling is a known regulator of cancer stem cell (CSC) features in colorectal cancer (CRC), though the effects of its heterogenous signaling on CRC cell stemness are only just emerging. In this review, we discuss how Notch ligand-receptor specificity contributes to regulating stemness, self-renewal, chemoresistance and cancer stem cells heterogeneity in CRC.

Steroidal alkaloid solanidine impedes hypoxia-driven ATM phosphorylation to switch on anti-angiogenesis in lung adenocarcinoma

PURPOSE

The declined oxygen tension in the cancer cell leads to the hypoxic adaptive response and favors establishment of tumor micro environment [TEM]. The complex TME consists of interwoven hypoxic HIF-1α and DNA damage repair ATM signaling. The ATM/HIF-1α phosphorylation switch on angiogenesis and abort apoptosis. Targeting this signaling nexus would be a novel therapeutic strategy for the treatment of cancer.

BACKGROUND

Steroidal alkaloid solanidine is known for varied pharmacological role but with less molecular evidences. Our earlier findings on solanidine proven its anti-neoplastic activity by inducing apoptosis in lung cancer. In continued research, efforts have been made to establish the underlying molecular signaling in induction of DNA damage in prevailing hypoxic TME.

METHODS

The solanidine induced DNA damage was assessed trough alkali COMET assay; signaling nexus and gene expression profile analysis through IB, qRT-PCR, Gelatin Zymography, IHC, IF and ELISA. Pathophysiological modulations assessed through tube formation, migration, invasion assays. Anti-angiogenic studies through CAM, rat aorta, matrigel assays and corneal neovascularization assay. Anti-tumor activity through in-vivo DLA ascites tumor model and LLC model.

RESULTS

The results postulates, inhibition of hypoxia driven DDR proteins pATMser1981/pHIF-1αser696 by solanidine induces anti-angiogenesis. Systematic study of both non-tumorigenic and tumorigenic models in-vitro as well as in-vivo experimental system revealed the angio-regression mediated anticancer effect in lung cancer. These effects are due to the impeded expression of angiogenic mediators such as VEGF, MMP2&9 and inflammatory cytokines IL6 and TNFα to induce pathophysiological changes CONCLUSION: The study establishes new role of solanidine by targeting ATM/HIF-1α signaling to induce anti-angiogenesis for the first time. The study highlights the potentiality of plant based phytomedicine solanidine which can targets the multiple hallmarks of cancer by targeting interwoven signaling crosstalk. Such an approach through solanidine necessary to counteract heterogeneous complexity of cancer which could be nearly translated into drug.

Curcumin, calebin A and chemosensitization: How are they linked to colorectal cancer?

Colorectal cancer (CRC) is one of the leading malignant diseases worldwide with a high rate of metastasis and poor prognosis. Treatment options include surgery, which is usually followed by chemotherapy in advanced CRC. With treatment, cancer cells could become resistant to classical cytostatic drugs such as 5-fluorouracil (5-FU), oxaliplatin, cisplatin, and irinotecan, resulting in chemotherapeutic failure. For this reason, there is a high demand for health-preserving re-sensitization mechanisms including the complementary use of natural plant compounds. Calebin A and curcumin, two polyphenolic turmeric ingredients derived from the Asian Curcuma longa plant, demonstrate versatile anti-inflammatory and cancer-reducing abilities, including CRC-combating capacity. After an insight into their epigenetics-modifying holistic health-promoting effects, this review compares functional anti-CRC mechanisms of multi-targeting turmeric-derived compounds with mono-target classical chemotherapeutic agents. Furthermore, the reversal of resistance to chemotherapeutic drugs was presented by focusing on calebin A's and curcumin's capabilities to chemosensitize or re-sensitize CRC cells to 5-FU, oxaliplatin, cisplatin, and irinotecan. Both polyphenols enhance the receptiveness of CRC cells to standard cytostatic drugs converting them from chemoresistant into non-chemoresistant CRC cells by modulating inflammation, proliferation, cell cycle, cancer stem cells, and apoptotic signaling. Therefore, calebin A and curcumin can be tested for their ability to overcome cancer chemoresistance in preclinical and clinical trials. The future perspective of involving turmeric-ingredients curcumin or calebin A as an additive treatment to chemotherapy for patients with advanced metastasized CRC is explained.

AGA induces sub-G1 cell cycle arrest and apoptosis in human colon cancer cells through p53-independent/p53-dependent pathway

BACKGROUND

Despite the advancement in chemotherapeutic drugs for colon cancer treatment, it is still a life-threatening disease worldwide due to drug resistance. Therefore, an urgently needed to develop novel drugs for colon cancer therapies. AGA is a combination of traditional Chinese medicine Antler's extract (A), Ganoderma lucidum (G), and Antrodia camphorata (A); it contains a lot of biomolecules like polysaccharides, fatty acids, and triterpenoids that are known to exerting anti-oxidative, anti-inflammatory, anti-microbial and anti-tumor activities in oral cancer. In this study, we investigate AGA anti-proliferative, anti-metastatic and apoptotic activity to explore its anti-cancer activity against colon cancer cells and its underlying mechanism.

METHOD

Here, in-vitro studies were performed to determine the antiproliferative activity of AGA through MTT and colony formation assays. Wound healing and transwell migration assay were used to evaluate the metastasis. Flow cytometry and protein expression were used to investigate the involved molecular mechanism by evaluating the cell cycle and apoptosis. The in-vivo anti-cancerous activity of AGA was assessed by xenograft mice model of colon cancer cells.

RESULTS

We found that AGA significantly inhibited the proliferative capacity and metastasis of colon cancer cells in-vitro. In addition, AGA induced cell cycle arrest in the sub-G1 phase through upregulating p21 and downregulating CDK2, CDK6 in SW620, and CDK4 in SW480 and HT29, respectively. Annexin-v assay indicated that colon cancer cells had entered early and late apoptosis after treatment with AGA. Furthermore, a mechanistic protein expressions study revealed that AGA in p53-dependent and independent regulated the apoptosis of colon cancer by downregulating the p53 protein expression in SW620 and SW480 cells but upregulating in a dose-dependent manner in HT29 cells and increasing the expression of Bax and caspase-9 to inhibit the colon cancer cells. In vivo study, we found that AGA significantly reduced the xenograft tumor growth in NOD/SCID mice with no adverse effect on the kidney and liver.

CONCLUSION

Collectively, AGA has the potential to inhibit colon cancer through inhibiting proliferation, migration, and cell cycle kinase by upregulating p21 protein expression and promoting the apoptotic protein in a p53-dependent and independent manner.

CT-based radiogenomic analysis dissects intratumor heterogeneity and predicts prognosis of colorectal cancer: a multi-institutional retrospective study

BACKGROUND

This study aimed to develop a radiogenomic prognostic prediction model for colorectal cancer (CRC) by investigating the biological and clinical relevance of intratumoural heterogeneity.

METHODS

This retrospective multi-cohort study was conducted in three steps. First, we identified genomic subclones using unsupervised deconvolution analysis. Second, we established radiogenomic signatures to link radiomic features with prognostic subclone compositions in an independent radiogenomic dataset containing matched imaging and gene expression data. Finally, the prognostic value of the identified radiogenomic signatures was validated using two testing datasets containing imaging and survival information collected from separate medical centres.

RESULTS

This multi-institutional retrospective study included 1601 patients (714 females and 887 males; mean age, 65 years ± 14 [standard deviation]) with CRC from 5 datasets. Molecular heterogeneity was identified using unsupervised deconvolution analysis of gene expression data. The relative prevalence of the two subclones associated with cell cycle and extracellular matrix pathways identified patients with significantly different survival outcomes. A radiogenomic signature-based predictive model significantly stratified patients into high- and low-risk groups with disparate disease-free survival (HR = 1.74, P = 0.003). Radiogenomic signatures were revealed as an independent predictive factor for CRC by multivariable analysis (HR = 1.59, 95% CI:1.03-2.45, P = 0.034). Functional analysis demonstrated that the 11 radiogenomic signatures were predominantly associated with extracellular matrix and immune-related pathways.

CONCLUSIONS

The identified radiogenomic signatures might be a surrogate for genomic signatures and could complement the current prognostic strategies.

An integrated multi-omics analysis of topoisomerase family in pan-cancer: Friend or foe?

BACKGROUND

Topoisomerases are nuclear enzymes that get to the bottom of topological troubles related with DNA all through a range of genetic procedures. More and more studies have shown that topoisomerase-mediated DNA cleavage plays crucial roles in tumor cell death and carcinogenesis. There is however still a lack of comprehensive multi-omics studies related to topoisomerase family genes from a pan-cancer perspective.

METHODS

In this study, a multiomics pan-cancer analysis of topoisomerase family genes was conducted by integrating over 10,000 multi-dimensional cancer genomic data across 33 cancer types from The Cancer Genome Atlas (TCGA), 481 small molecule drug response data from cancer therapeutics response portal (CTRP) as well as normal tissue data from Genotype-Tissue Expression (GTEx). Finally, overall activity-level analyses of topoisomerase in pan-cancers were performed by gene set variation analysis (GSVA), together with differential expression, clinical relevancy, immune cell infiltration and regulation of cancer-related pathways.

RESULTS

Dysregulated gene expression of topoisomerase family were related to genomic changes and abnormal epigenetic modifications. The expression levels of topoisomerase family genes could significantly impact cancer progression, intratumoral heterogeneity, alterations in the immunological condition and regulation of the cancer marker-related pathways, which in turn caused the differences in potential drugs sensitivity and the distinct prognosis of patients.

CONCLUSION

It was anticipated that topoisomerase family genes would become novel prognostic biomarkers for cancer patients and provide new insights for the diagnosis and treatment of tumors.

Role, molecular mechanism and the potential target of breast cancer stem cells in breast cancer development

Breast cancer (BC) is one of the most common malignant tumors in women globally, and its occurrence has surpassed lung cancer and become the biggest threat for women. At present, breast cancer treatment includes surgical resection or postoperative chemotherapy and radiotherapy. However, tumor relapse and metastasis usually lead to current therapy failure thanks to breast cancer stem cells (BCSCs)-mediated tumorigenicity and drug resistance. Drug resistance is mainly due to the long-term quiescent G0 phase, strong DNA repairability, and high expression of ABC transporter, and the tumorigenicity is reflected in the activation of various proliferation pathways related to BCSCs. Therefore, understanding the characteristics of BCSCs and their intracellular and extracellular molecular mechanisms is crucial for the development of targeted drugs for BCSCs. To this end, we discussed the latest developments in BCSCs research, focusing on the analysis of specific markers, critical signaling pathways that maintain the stemness of BCSCs，such as NOTCH, Wnt/β-catenin, STAT3, Hedgehog, and Hippo-YAP signaling, immunomicroenviroment and summarizes targeting therapy strategies for stemness maintenance and differentiation, which provides a theoretical basis for further exploration of treating breast cancer and preventing relapse derived from BCSCs.

Drug Repositioning Based on the Reversal of Gene Expression Signatures Identifies TOP2A as a Therapeutic Target for Rectal Cancer

Rectal cancer is a common disease with high mortality rates and limited therapeutic options. Here we combined the gene expression signatures of rectal cancer patients with the reverse drug-induced gene-expression profiles to identify drug repositioning candidates for cancer therapy. Among the predicted repurposable drugs, topoisomerase II inhibitors (doxorubicin, teniposide, idarubicin, mitoxantrone, and epirubicin) presented a high potential to reverse rectal cancer gene expression signatures. We showed that these drugs effectively reduced the growth of colorectal cancer cell lines closely representing rectal cancer signatures. We also found a clear correlation between topoisomerase 2A (TOP2A) gene copy number or expression levels with the sensitivity to topoisomerase II inhibitors. Furthermore, CRISPR-Cas9 and shRNA screenings confirmed that loss-of-function of the TOP2A has the highest efficacy in reducing cellular proliferation. Finally, we observed significant TOP2A copy number gains and increased expression in independent cohorts of rectal cancer patients. These findings can be translated into clinical practice to evaluate TOP2A status for targeted and personalized therapies based on topoisomerase II inhibitors in rectal cancer patients.

Multi-Gene Testing Overview with a Clinical Perspective in Metastatic Triple-Negative Breast Cancer

Next-generation sequencing (NGS) is the technology of choice for the routine screening of tumor samples in clinical practice. In this setting, the targeted sequencing of a restricted number of clinically relevant genes represents the most practical option when looking for genetic variants associated with cancer, as well as for the choice of targeted treatments. In this review, we analyze available NGS platforms and clinical applications of multi-gene testing in breast cancer, with a focus on metastatic triple-negative breast cancer (mTNBC). We make an overview of the clinical utility of multi-gene testing in mTNBC, and then, as immunotherapy is emerging as a possible targeted therapy for mTNBC, we also briefly report on the results of the latest clinical trials involving immune checkpoint inhibitors (ICIs) and TNBC, where NGS could play a role for the potential predictive utility of homologous recombination repair deficiency (HRD) and tumor mutational burden (TMB).

DNA damage response and repair in pancreatic cancer development and therapy

Pancreatic cancer (PC) is among fatal malignancies, with a dismal prognosis and a low survival rate of 5-10%. In both sporadic and inherited PC, gene alterations, such as BRCA1/2, PALB2, and ATM, can occur frequently. Currently, surgery, chemo- and radio-therapy are the most common therapeutic strategies for treating this cancer. DNA damage response (DDR) establishes multiple pathways that eliminate DNA damage sites to maintain genomic integrity. Various types of cancers and age-related diseases are associated with DDR machinery defects. According to the severity of the damage, DDR pathways respond appropriately to lesions through repairing damage, arresting the cell cycle, or apoptosis. Recently, novel agents, particularly those targeting DDR pathways, are being utilized to improve the response of many cancers to chemotherapy and radiotherapy. In this paper, we briefly reviewed DDR processes and their components, including DDR sensors, DDR mediators, and DDR transducers in the progression, prognosis, and treatment of PC.

Identification and Characterization of MortaparibPlus-A Novel Triazole Derivative That Targets Mortalin-p53 Interaction and Inhibits Cancer-Cell Proliferation by Wild-Type p53-Dependent and -Independent Mechanisms

p53 has an essential role in suppressing the carcinogenesis process by inducing cell cycle arrest/apoptosis/senescence. Mortalin/GRP75 is a member of the Hsp70 protein family that binds to p53 causing its sequestration in the cell cytoplasm. Hence, p53 cannot translocate to the nucleus to execute its canonical tumour suppression function as a transcription factor. Abrogation of mortalin-p53 interaction and subsequent reactivation of p53's tumour suppression function has been anticipated as a possible approach in developing a novel cancer therapeutic drug candidate. A chemical library was screened in a high-content screening system to identify potential mortalin-p53 interaction disruptors. By four rounds of visual assays for mortalin and p53, we identified a novel synthetic small-molecule triazole derivative (4-[(1E)-2-(2-phenylindol-3-yl)-1-azavinyl]-1,2,4-triazole, henceforth named Mortaparib^Plus). Its activities were validated using multiple bioinformatics and experimental approaches in colorectal cancer cells possessing either wild-type (HCT116) or mutant (DLD-1) p53. Bioinformatics and computational analyses predicted the ability of Mortaparib^Plus to competitively prevent the interaction of mortalin with p53 as it interacted with the p53 binding site of mortalin. Immunoprecipitation analyses demonstrated the abrogation of mortalin-p53 complex formation in Mortaparib^Plus-treated cells that showed growth arrest and apoptosis mediated by activation of p21^WAF1, or BAX and PUMA signalling, respectively. Furthermore, we demonstrate that Mortaparib^Plus-induced cytotoxicity to cancer cells is mediated by multiple mechanisms that included the inhibition of PARP1, up-regulation of p73, and also the down-regulation of mortalin and CARF proteins that play critical roles in carcinogenesis. Mortaparib^Plus is a novel multimodal candidate anticancer drug that warrants further experimental and clinical attention.

Small molecule 2,3-DCPE induces S phase arrest by activating the ATM/ATR-Chk1-Cdc25A signaling pathway in DLD-1 colon cancer cells

In our previous study, it was reported that 2[[3-(2,3-dichlorophenoxy)propyl]amino]ethanol (2,3-DCPE) induces apoptosis and cell cycle arrest. The current study aimed to investigate the molecular mechanism involved in 2,3-DCPE-induced S phase arrest. The results demonstrated that 2,3-DCPE upregulated phosphorylated (p-)H2A histone family member X, a biomarker of DNA damage, in the DLD-1 colon cancer cell line. Western blotting revealed that 2,3-DCPE increased the checkpoint kinase (Chk)1 (Ser317 and Ser345) level and decreased the expression of M-phase inducer phosphatase 1 (Cdc25A) in a time-dependent manner. Subsequently, the results demonstrated that the ataxia-telangiectasia mutated (ATM) and ataxia-telangiectasia and Rad3-related (ATR) inhibitors wortmannin and caffeine had no effect on the cell cycle; however, the inhibitors partially abrogated 2,3-DCPE-induced S phase arrest. Flow cytometry assays revealed that caffeine (2 mM) reduced the proportion of S phase cells from 83 to 39.6% and that wortmannin (500 nM) reduced the proportion of S phase cells from 83 to 48.2%. Furthermore, wortmannin and caffeine inhibited the 2,3-DCPE-mediated phosphorylation of Chk1 and the degradation of Cdc25A. However, these ATM/ATR inhibitors had limited effect on 2,3-DCPE-induced apoptosis. Taken together, the data of the current study indicated that 2,3-DCPE caused DNA damage in colon cancer cells and that 2,3-DCPE-induced S phase arrest was associated with the activation of the ATM/ATR-Chk1-Cdc25A pathway.

ERCC1, PARP-1, and AQP1 as predictive biomarkers in colon cancer patients receiving adjuvant chemotherapy

BACKGROUND

The recognition of high-risk colon cancer patients prone to chemoresistant and recurrent disease is a challenge.

OBJECTIVES

We aimed to assess the immunohistochemical expression of ERCC1, PARP-1, and AQP1 in 60 cases of stage II and III colon cancer who underwent curative resection and adjuvant chemotherapy. Their predictive role of tumor progression and disease-free survival (DFS) was analyzed.

METHODS

The immunohistochemical expression of ERCC1, PARP-1, and AQP1 in 60 cases of stage II and III colon cancer who underwent curative resection and adjuvant chemotherapy was studied. The collected data on the overall survival (OS), disease-free survival (DFS), and the response to the chemotherapy were analyzed.

RESULTS

Positive nuclear ERCC1 expression was identified in 58.3% of the patients, ERCC1 expression was significantly associated with left-sided tumors (P< 0.01). Moreover, its expression was significantly associated with the aggressive tumor characteristics including high grade, lymph node metastasis and advanced tumor stage (P< 0.001 for each). High nuclear PARP-1 expression was observed in 63.3% of the cases, and its expression was significantly associated with tumor grade and lymph node metastasis (P= 0.003 for each). Positive membranous AQP1 expression was identified in 41.7% of patients, and it was associated with high grade, lymph node metastasis and advanced tumor stage (P< 0.001 for each). During the follow-up period, 23 patients (38.3%) exhibited a tumor progression; this was significantly associated with positive ERCC1, high PARP-1, and negative AQP1 expression. Statistics of the survival data revealed that shorter DFS was significantly associated with positive ERCC1, high PARP-1, and positive AQP1 expression (P= 0.005, 0.016, 0.002, respectively).

CONCLUSIONS

ERCC1, PARP1, and AQP1 are adverse prognostic biomarkers in stage II-III colon cancer. Moreover, adjuvant chemotherapy may not be beneficial for patients with positive ERCC1, high PARP1, and AQP1-negative tumors. Therefore, we recommend that ERCC1, PARP-1, and AQP1 should be assessed during the selection of the treatment strategy for stage II-III colon cancer patients.

The Roles of Cancer Stem Cells and Therapy Resistance in Colorectal Carcinoma

Cancer stem cells (CSCs) are the main culprits involved in therapy resistance and disease recurrence in colorectal carcinoma (CRC). Results using cell culture, animal models and tissues from patients with CRC suggest the indispensable roles of colorectal CSCs in therapeutic failure. Conventional therapies target proliferating and mature cancer cells, while CSCs are mostly quiescent and poorly differentiated, thereby they can easily survive chemotherapeutic insults. The aberrant activation of Wnt/β-catenin, Notch, Hedgehog, Hippo/YAP (Yes-associated protein) and phosphatidylinositol 3-kinase/protein kinase B facilitates CSCs with excessive self-renewal and therapy resistance property in CRC. CSCs survive the chemo-radiotherapies by escaping therapy mediated DNA damage via altering the cell cycle checkpoints, increasing DNA damage repair capacity and by an efficient scavenging of reactive oxygen species. Furthermore, dysregulations of miRNAs e.g., miR-21, miR-93, miR-203, miR-215, miR-497 etc., modulate the therapeutic sensitivity of colorectal CSCs by regulating growth and survival signalling. In addition, a reversible quiescent G₀ state and the re-entering cell cycle capacity of colorectal CSCs can accelerate tumour regeneration after treatment. Moreover, switching to favourable metabolic signatures during a therapeutic regimen will add more complexity in therapeutic outcomes against CSCs. Therapeutic strategies targeting these underlying mechanisms of CSCs’ therapy resistance could provide a promising outcome, however, deep understanding and concerted research are necessary to design novel therapies targeting CSCs. To conclude, the understanding of these mechanisms of CSC in CRC could lead to the improved management of patients with CRC.

Bioinformatics Analysis of Key Genes and Pathways in Colorectal Cancer

Colorectal cancer (CRC) is the third most prevalent cancer in the world. Although great progress has been made, the specific molecular mechanism remains unclear. This study aimed to explore the differentially expressed genes (DEGs) and underlying mechanisms of CRC using bioinformatics analysis. In this study, we identified a total of 1353 DEGs in the database of GSE113513, including 715 up- and 638 downregulated genes. Gene ontology analysis results showed that upregulated DEGs were significantly enriched in cell division, cell proliferation, and DNA replication. The downregulated DEGs were enriched in immune response, relation of cell growth and inflammatory response. The Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that upregulated DEGs were enriched in cell cycle and p53 signaling pathway, whereas the downregulated DEGs were enriched in drug metabolism, metabolism of xenobiotics by cytochrome P450, and nitrogen metabolism. A total of 124 up-key genes and 35 down-key genes were identified from the protein-protein interaction networks. Furthermore, we identified five up-modules (up-A, up-B, up-C, up-D, and up-E) and three down-modules (d-A, d-B, and d-C) by module analysis. The module up-A was enriched in sister chromatid cohesion, cell division, and mitotic nuclear division. Pathways associated with cell cycle, progesterone-mediated oocyte maturation, oocyte meiosis, and p53 signaling pathway. Whereas the d-A was mainly enriched in G-protein coupled receptor signaling pathway, cell chemotaxis, and chemokine-mediated signaling pathway. The pathways enriched in chemokine signaling pathway, cytokine-cytokine receptor interaction, and alcoholism. These key genes and pathways might be used as molecular targets and diagnostic biomarkers for the treatment of CRC.

Potential biomarkers associated with oxidative stress for risk assessment of colorectal cancer

Cells are continuously threatened by the damage caused by reactive oxygen/nitrogen species (ROS/RNS), which are produced during physiological oxygen metabolism. In our review, we will summarize the latest reports on the role of oxidative stress and oxidative stress-induced signaling pathways in the etiology of colorectal cancer. The differences in ROS generation may influence the levels of oxidized proteins, lipids, and DNA damage, thus contributing to the higher susceptibility of colon. Reactive species (RS) of various types are formed and are powerful oxidizing agents, capable of damaging DNA and other biomolecules. Increased formation of RS can promote the development of malignancy, and the "normal" rates of RS generation may account for the increased risk of cancer development in the aged. In this review, we focus on the role of oxidative stress in the etiology of colorec-tal cancer and discuss free radicals and free radical-stimulated pathways in colorectal carcinogenesis.

How does inflammation drive mutagenesis in colorectal cancer?

Colorectal cancer (CRC) is a major health challenge worldwide. Factors thought to be important in CRC etiology include diet, microbiome, exercise, obesity, a history of colon inflammation and family history. Interventions, including the use of non-steroidal anti-Inflammatory drugs (NSAIDs) and anti-inflammatory agents, have been shown to decrease incidence in some settings. However, our current understanding of the mechanistic details that drive CRC are insufficient to sort out the complex and interacting factors responsible for cancer-initiating events. It has been known for some time that the development of CRC involves mutations in key genes such as p53 and APC, and the sequence in which these mutations occur can determine tumor presentation. Observed recurrent mutations are dominated by C to T transitions at CpG sites, implicating the deamination of 5-methylcytosine (5mC) as a key initiating event in cancer-driving mutations. While it has been widely assumed that inflammation-mediated oxidation drives mutations in CRC, oxidative damage to DNA induces primarily G to T transversions, not C to T transitions. In this review, we discuss this unresolved conundrum, and specifically, we elucidate how the known nucleotide excision repair (NER) and base excision repair (BER) pathways, which are partially redundant and potentially competing, might provide a critical link between oxidative DNA damage and C to T mutations. Studies using recently developed next-generation DNA sequencing technologies have revealed the genetic heterogeneity in human tissues including tumors, as well as the presence of DNA damage. The capacity to follow DNA damage, repair and mutagenesis in human tissues using these emerging technologies could provide a mechanistic basis for understanding the role of oxidative damage in CRC tumor initiation. The application of these technologies could identify mechanism-based biomarkers useful in earlier diagnosis and aid in the development of cancer prevention strategies.

PARP-1 inhibitor sensitizes arsenic trioxide in hepatocellular carcinoma cells via abrogation of G2/M checkpoint and suppression of DNA damage repair

Arsenic trioxide (ATO) is successfully used to treat hematological malignancies. However, the clinical application of the agent in solid tumors is largely limited by its dose-dependent toxicity which results from the high intrinsic resistance of the cancer cells. In this study, we firstly identified a series of sensitization effects of 4AN, a PARP-1 inhibitor, on human hepatocellular carcinoma cell line HepG2 to ATO treatment. We showed that treatment of HepG2 cells with 4AN promoted ATO-induced cell death in a synergistic manner. The ATO-sensitization by 4AN was associated with its effect on abrogation of ATO-induced G2/M checkpoint which impairs DNA damage repair and promotes cell apoptosis. Further analysis demonstrated that the ATO-induced G2/M checkpoint was closely related to a decrease in cyclin B1, a key G2/M mediator; whereas 4AN up-regulated the expression of cyclin B1 in ATO-treated cells, which may be at least partly responsible for its effect on abrogation of ATO-induced G2/M checkpoint. This was further supported by the result showing that down-regulation of cyclin B1 using siRNA could restore the G2/M checkpoint in cells co-treated with ATO and 4AN, thereby improving DNA damage repair and decreasing apoptosis. Our study indicates that the abrogation of G2/M checkpoint and the suppression of DNA damage repair contribute to ATO-sensitization by PARP-1 inhibitor in HepG2 cells, which provides a novel insight into the chemo-sensitization mechanism of PARP-1 inhibitor.

Effect of APE1 T2197G (Asp148Glu) polymorphism on APE1, XRCC1, PARP1 and OGG1 expression in patients with colorectal cancer

It has been hypothesized that genetic variation in base excision repair (BER) might modify colorectal adenoma risk. Thus, we evaluated the influence of APE1 T2197G (Asp148Glu) polymorphism on APE1, XRCC1, PARP1 and OGG1 expression in normal and tumor samples from patients with colorectal cancer. The results indicate a downregulation of OGG1 and an upregulation of XRCC1 expression in tumor tissue. Regarding the anatomical location of APE1, OGG1 and PARP-1, a decrease in gene expression was observed among patients with cancer in the rectum. In patients with or without some degree of tumor invasion, a significant downregulation in OGG1 was observed in tumor tissue. Interestingly, when taking into account the tumor stage, patients with more advanced grades (III and IV) showed a significant repression for APE1, OGG1 and PARP-1. XRCC1 expression levels were significantly enhanced in tumor samples and were correlated with all clinical and histopathological data. Concerning the polymorphism T2197G, GG genotype carriers exhibited a significantly reduced expression of genes of the BER repair system (APE1, XRCC1 and PARP1). In summary, our data show that patients with colorectal cancer present expression changes in several BER genes, suggesting a role for APE1, XRCC1, PARP1 and OGG1 and APE1 polymorphism in colorectal carcinogenesis.

Clinical significance and association of RUNX3 hypermethylation frequency with colorectal cancer: a meta-analysis

Background

The RUNX family, which is composed of RUNX1, RUNX2, and RUNX3, is a sequence-specific transcription factor family and is closely involved in a variety of cellular processes including development, differentiation, participation in the regulation of p53-dependent DNA damage response and/or tumorigenesis. Emerging evidence indicates that RUNX3 is a candidate tumor suppressor in several types of human tumors including colorectal cancer (CRC). However, the correlation of RUNX3 inactivation with CRC remains unclear. In the study reported here, we conducted a systematic review and meta-analysis to quantitatively evaluate the effects of RUNX3 hypermethylation/expression on the incidence of CRC.

Methods

A detailed search of the literature was made using Medline^® and Web of Science for related research publications written in English. The methodological quality of the studies was also evaluated. The data were extracted and assessed by two reviewers independently. Analyses of the pooled data were performed. Odds ratios (ORs) and hazard ratios were calculated and summarized, respectively.

Results

A final analysis of 1,427 CRC patients from eleven eligible studies was performed. We observed that RUNX3 hypermethylation was significantly higher in CRC than in normal colorectal mucosa. The pooled OR from six studies comprising 289 CRC and 188 normal colorectal mucosa was OR =0.07 (confidence interval [CI] =0.03–0.18, P<0.00001). Aberrant RUNX3 hypermethylation/expression was significantly higher in advanced CRC than in early staged CRC (OR =0.54, CI =0.41–0.71, P<0.0001). Aberrant RUNX3 hypermethylation/expression was also significantly higher in microsatellite instability (MSI)-positive CRC than in MSI-negative CRC (OR =0.44, CI =0.3–0.66, P<0.0001). In addition, CRC patients with RUNX3 hypermethylation or lacking RUNX3 protein expression had a lower survival rate than those without RUNX3 hypermethylation or those who did not express RUNX3 protein.

Conclusion

The results of this meta-analysis suggest that RUNX3 hypermethylation is associated with an increased risk of CRC, increased risk of progression of CRC, and a poorer CRC survival rate. RUNX3 hypermethylation, which induces the inactivation of RUNX3 gene, plays an important role in colorectal carcinogenesis, high levels of MSI, as well as CRC progression and development.

Metabolomics of ApcMin/+ mice genetically susceptible to intestinal cancer

Background

To determine how diets high in saturated fat could increase polyp formation in the mouse model of intestinal neoplasia, Apc^Min/+, we conducted large-scale metabolome analysis and association study of colon and small intestine polyp formation from plasma and liver samples of Apc^Min/+ vs. wild-type littermates, kept on low vs. high-fat diet. Label-free mass spectrometry was used to quantify untargeted plasma and acyl-CoA liver compounds, respectively. Differences in contrasts of interest were analyzed statistically by unsupervised and supervised modeling approaches, namely Principal Component Analysis and Linear Model of analysis of variance. Correlation between plasma metabolite concentrations and polyp numbers was analyzed with a zero-inflated Generalized Linear Model.

Results

Plasma metabolome in parallel to promotion of tumor development comprises a clearly distinct profile in Apc^Min/+ mice vs. wild type littermates, which is further altered by high-fat diet. Further, functional metabolomics pathway and network analyses in Apc^Min/+ mice on high-fat diet revealed associations between polyp formation and plasma metabolic compounds including those involved in amino-acids metabolism as well as nicotinamide and hippuric acid metabolic pathways. Finally, we also show changes in liver acyl-CoA profiles, which may result from a combination of Apc^Min/+-mediated tumor progression and high fat diet. The biological significance of these findings is discussed in the context of intestinal cancer progression.

Conclusions

These studies show that high-throughput metabolomics combined with appropriate statistical modeling and large scale functional approaches can be used to monitor and infer changes and interactions in the metabolome and genome of the host under controlled experimental conditions. Further these studies demonstrate the impact of diet on metabolic pathways and its relation to intestinal cancer progression. Based on our results, metabolic signatures and metabolic pathways of polyposis and intestinal carcinoma have been identified, which may serve as useful targets for the development of therapeutic interventions.

CCT128930 induces cell cycle arrest, DNA damage, and autophagy independent of Akt inhibition

PI3K/Akt/mTOR pathway plays an important role in tumor progression and anti-cancer drug resistance. The aim of the present study is to determine the antitumor effect of CCT128930, a novel small molecule inhibitor of Akt, in the HepG2 hepatoma cancer cells. Our results showed that at low concentrations, CCT128930 increased, but not inhibited, the phosphorylation of Akt in HepG2 and A549 cells. CCT128930 inhibited cell proliferation by inducing cell cycle arrest in G1 phase through downregulation of cyclinD1 and Cdc25A, and upregulation of p21, p27 and p53. A higher dose (20 μM) of CCT128930 triggered cell apoptosis with activation of caspase-3, caspase-9, and PARP. Treatment with CCT128930 increased phosphorylation of ERK and JNK in HepG2 cells. CCT128930 activated DNA damage response of HepG2 cell characterized by phosphorylation of H2AX, ATM (ataxia-telangiectasia mutated), Chk1 and Chk2. Upon exposure to CCT128930 at a higher concentration, HepG2 cells exhibited autophagy was accompanied by an increase the levels of LC3-II and Beclin-1. Blocking autophagy using chloroquine magnified CCT128930-induced apoptotic cell death and the phosphorylation of H2AX. The results in this study have advanced our current understandings of the anti-cancer mechanisms of CCT128930 in cancer cells.

OSU-CG5, a novel energy restriction mimetic agent, targets human colorectal cancer cells in vitro

AIM

Energy-restriction mimetic agents (ERMAs) are small-molecule agents that target various aspects of energy metabolism, which has emerged as a promising approach in cancer therapy. In the current study, we tested the ability of OSU-CG5, a novel ERMA, to target human colorectal cancer (CRC) in vitro.

METHODS

Two human CRC cell lines (HCT-116 and Caco-2) were tested. Cell viability was assessed using MTT assay. Caspase-3/7 activities were measured using Caspase-Glo 3/7 assay kit. Western blot analysis was used to measure the expression of relevant proteins in the cells. Glucose consumption of the cells was detected using glucose uptake cell-based assay kit.

RESULTS

OSU-CG5 dose-dependently inhibited HCT-116 and Caco-2 cell proliferation with the IC₅₀ values of 3.9 and 4.6 μmol/L, respectively, which were 20-25-fold lower than those of resveratrol, a reference ERMA. Both OSU-CG5 (5, 10, and 20 μmol/L) and resveratrol (50, 100, and 200 μmol/L) dose-dependently increased caspase-3/7 activity and PARP level in the cells. Furthermore, both OSU-CG5 and resveratrol induced dose-dependent energy restriction in the cells: they suppressed glucose uptake and Akt phosphorylation, decreased the levels of p-mTOR and p-p70S6K, increased the levels of ER stress response proteins GRP78 and GADD153, and increased the level of β-TrCP, which led to the downregulation of cyclin D1 and Sp1.

CONCLUSION

OSU-CG5 exhibits promising anti-cancer activity against human CRC cells in vitro, which was, at least in part, due to energy restriction and the consequent induction of ER stress and apoptosis.

Terfenadine induces anti-proliferative and apoptotic activities in human hormone-refractory prostate cancer through histamine receptor-independent Mcl-1 cleavage and Bak up-regulation

Although the results of several studies have underscored the regulatory effect of H1-histamine receptors in cell proliferation of some cancer cell types, its effect in prostate cancers remains unclear. We have therefore studied the effect of terfenadine (an H1-histamine receptor antagonist) in prostate cancer cell lines. Our data demonstrate that terfenadine was effective against PC-3 and DU-145 cells (two prostate cancer cell lines). In contrast, based on the sulforhodamine B assay, loratadine had less potency while fexofenadine and diphenhydramine had little effect. Terfenadine induced the cleavage of Mcl-1 cleavage into a pro-apoptotic 28-kDa fragment and up-regulation of Bak, resulting in the loss of mitochondrial membrane potential (ΔΨm) and the release of cytochrome c and apoptosis-inducing factor into the cytosol. The activation of caspase cascades was detected to be linked to terfenadine action. Bak up-regulation was also examined at both the transcriptional and translational levels, and Bak activation was validated based on conformational change to expose the N terminus. Terfenadine also induced an indirect-but not direct-DNA damage response through the cleavage and activation of caspase-2, phosphorylation and activation of Chk1 and Chk2 kinases, phosphorylation of RPA32 and acetylation of Histone H3; these processes were highly correlated to severe mitochondrial dysfunction and the activation of caspase cascades. In conclusion, terfenadine induced apoptotic signaling cascades against HRPCs in a sequential manner. The exposure of cells to terfenadine caused the up-regulation and activation of Bak and the cleavage of Mcl-1, leading to the loss of ΔΨm and activation of caspase cascades which further resulted in DNA damage response and cell apoptosis.

On biomarkers and pathways in rectal cancer: What's the target?

In spite of tremendous progresses in surgical and chemo-radiotherapeutic regimens, rectal cancer still suffers from high relapse and mortality rates, and metastatic disease is incurable. Here we assess some of the most recent and validated biomarkers and potential targets studied in rectal cancer, and provide comments to a recent monographic topic covering several aspects of colorectal cancer, published in Current Cancer Drug Targets.