Demethylation restores SN38 sensitivity in cells with acquired resistance to SN38 derived from human cervical squamous cancer cells

A Phase I Trial of a Guadecitabine (SGI-110) and Irinotecan in Metastatic Colorectal Cancer Patients Previously Exposed to Irinotecan

PURPOSE

Chemotherapeutic resistance eventually develops in all patients with metastatic colorectal cancer (mCRC). Gene silencing through promoter demethylation is one potential reversible mechanism of resistance with administration of hypomethylating agents. We evaluated the safety and tolerability of guadecitabine and irinotecan in patients with mCRC previously treated with irinotecan.

PATIENTS AND METHODS

In this 3+3 dose-escalation study, patients with mCRC previously exposed to irinotecan received guadecitabine days 1 to 5 of a 28-day cycle and irinotecan 125 mg/m2 days 8 and 15 [dose level (DL) 1, guadecitabine 45 mg/m2; DL -1: guadecitabine 30 mg/m2; DL -1G: guadecitabine 30 mg/m2 with growth factor support (GFS); DL 1G: guadecitabine 45 mg/m2 with GFS].

RESULTS

Twenty-two patients were treated across four DLs. Dose-limiting toxicities were neutropenic fever (DL 1 and -1G), biliary drain infection (DL -1), colonic obstruction (DL -1), and severe dehydration (DL 1G). Most common toxicities were neutropenia (82% any grade, 77% Grade 3/4), neutropenic fever (23%), leukopenia (73% any grade, 50% Grade 3/4), and injection site reactions (64% total, 0% Grade 3/4). Patients received a median of 4.5 cycles of treatment; 12/17 evaluable patients had stable disease as best response, with one having initial disease progression but subsequently durable partial response. Circulating tumor DNA showed decrease in global demethylation by LINE-1 after treatment.

CONCLUSIONS

We report the first study of chemo-priming with epigenetic therapy in gastrointestinal cancers. Guadecitabine 45 mg/m2 and irinotecan 125 mg/m2 with GFS was safe and tolerable in patients with mCRC, with early indication of benefit. These data have provided the basis for an ongoing phase II randomized, multicenter trial.

Age-associated impairment of antitumor immunity in carcinoma-bearing mice and restoration by oral administration of Lentinula edodes mycelia extract

Because cancer is associated with aging, immunological features in the aged should be considered in anticancer immunotherapy. In this study, we investigated antitumor immunity in aged mice using a CT26 colon carcinoma model. The tumor growth of CT26 was accelerated in aged mice compared with that in young mice, but this difference was not observed in nude mice. The serum levels of IL-6 and TNF-α were higher in aged mice than those in young mice, irrespective of the CT26-bearing state. The in vitro induction of CT26-specific CTLs from aged mice that were vaccinated with doxorubicin (DTX)-treated CT26 cells was impaired. In vivo neutralization of IL-6, but not TNF-α, showed a tendency to restore the in vitro induction of CT26-specific CTLs from vaccinated aged mice. Analyses on tumor-infiltrating immune cells as early as day 5 after CT26 inoculation revealed that monocytic and granulocytic MDSCs preferentially infiltrated into tumor sites in aged mice compared with young mice. Alternatively, oral administration of Lentinula edodes mycelia (L.E.M.) extract, which has the potential to suppress inflammation in tumor-bearing hosts, decreased the serum levels of IL-6 in aged mice. When administration of L.E.M. extract was started 1 week earlier, CT26 growth was retarded in aged mice and the in vivo priming of tumor-specific CTLs was improved in CT26-vaccinated aged mice. These results indicate early infiltration of MDSCs is related to impaired immunity of aged hosts and that oral administration of L.E.M. extract can mitigate the impairment.

MiR-497 decreases cisplatin resistance in ovarian cancer cells by targeting mTOR/P70S6K1

The mechanism of cisplatin resistance in ovarian cancer is not clearly understood. In the present investigation, we found that the expression levels of miR-497 were reduced in chemotherapy-resistant ovarian cancer cells and tumor tissues due to hypermethylation of miR-497 promoter. Low miR-497 expression levels were associated with chemo-resistant phonotype of ovarian cancer. By analyzing the expression levels of miR-497, mTOR and p70S6K1 in a clinical gene-expression array dataset, we found that mTOR and p70S6K1, two proteins correlated to chemotherapy-resistance in multiple types of human cancers, were inversely correlated with miR-497 levels in ovarian cancer tissues. By using an orthotopic ovarian tumor model and a Tet-On inducible miR-497 expression system, our results demonstrated that overexpression of miR-497 sensitizes the resistant ovarian tumor to cisplatin treatment. Therefore, we suggest that miR-497 might be used as a therapeutic supplement to increase ovarian cancer treatment response to cisplatin.

Biological implications and therapeutic significance of DNA methylation regulated genes in cervical cancer

Cervical cancer is the second most common cancer among women worldwide. About 528,000 women are diagnosed with cervical cancer contributing to around 266,000 deaths, across the globe every year. Out of these, the burden of 226,000 (85%) deaths occurs in the developing countries, who are less resource intensive to manage the disease. This is despite the fact that cervical cancer is amenable for early detection due to its long and relatively well-known natural history prior to its culmination as invasive disease. Infection with high risk human papillomavirus (hrHPVs) is essential but not sufficient to cause cervical cancer. Although it was thought that genetic mutations alone was sufficient to cause cervical cancer, the current epidemiological and molecular studies have shown that HPV infection along with genetic and epigenetic changes are frequently associated and essential for initiation, development and progression of the disease. Moreover, aberrant DNA methylation in host and HPV genome can be utilized not only as biomarkers for early detection, disease progression, diagnosis and prognosis of cervical cancer but also to design effective therapeutic strategies. In this review, we focus on recent studies on DNA methylation changes in cervical cancer and their potential role as biomarkers for early diagnosis, prognosis and targeted therapy.

Characterization of regulatory sequences in alternative promoters of hypermethylated genes associated with tumor resistance to cisplatin

The development of cisplatin resistance in human cancers is controlled by multiple genes and leads to therapeutic failure. Hypermethylation of specific gene promoters is a key event in clinical resistance to cisplatin. Although the usage of multiple promoters is frequent in the transcription of human genes, the role of alternative promoters and their regulatory sequences have not yet been investigated in cisplatin resistance genes. In a new approach, we hypothesized that human cancers exploit the specific transcription factor-binding sites (TFBS) and CpG islands (CGIs) located in the alternative promoters of certain genes to acquire platinum drug resistance. To provide a useful resource of regulatory elements associated with cisplatin resistance, we investigated the TFBS and CGIs in 48 alternative promoters of 14 hypermethylated cisplatin resistance genes previously reported. CGIs prone to methylation were identified in 28 alternative promoters of 11 hypermethylated genes. The majority of alternative promoters harboring CGIs (93%) were clustered in one phylogenetic subclass, whereas the ones lacking CGIs were distributed in two unrelated subclasses. Regulatory sequences, initiator and TATA-532 prevailed over TATA-8 and were found in all the promoters. B recognition element (BRE) sequences were present only in alternative promoters harboring CGIs, but CCAAT and TAACC were found in both types of alternative promoters, whereas downstream promoter element sequences were significantly less frequent. Therefore, it was hypothesized that BRE and CGI sequences co-localized in alternative promoters of cisplatin resistance genes may be used to design molecular markers for drug resistance. A more extensive knowledge of alternative promoters and their regulatory elements in clinical resistance to cisplatin is likely to usher novel avenues for sensitizing human cancers to treatment.

Decitabine impact on the endocytosis regulator RhoA, the folate carriers RFC1 and FOLR1, and the glucose transporter GLUT4 in human tumors

Background

In 31 solid tumor patients treated with the demethylating agent decitabine, we performed tumor biopsies before and after the first cycle of decitabine and used immunohistochemistry (IHC) to assess whether decitabine increased expression of various membrane transporters. Resistance to chemotherapy may arise due to promoter methylation/downregulation of expression of transporters required for drug uptake, and decitabine can reverse resistance in vitro. The endocytosis regulator RhoA, the folate carriers FOLR1 and RFC1, and the glucose transporter GLUT4 were assessed.

Results

Pre-decitabine RhoA was higher in patients who had received their last therapy >3 months previously than in patients with more recent prior therapy (P = 0.02), and varied inversely with global DNA methylation as assessed by LINE1 methylation (r = −0.58, P = 0.006). Tumor RhoA scores increased with decitabine (P = 0.03), and RFC1 also increased in patients with pre-decitabine scores ≤150 (P = 0.004). Change in LINE1 methylation with decitabine did not correlate significantly with change in IHC scores for any transporter assessed. We also assessed methylation of the RFC1 gene (alias SLC19A1). SLC19A1 methylation correlated with tumor LINE1 methylation (r = 0.45, P = 0.02). There was a small (statistically insignificant) decrease in SLC19A1 methylation with decitabine, and there was a trend towards change in SLC19A1 methylation with decitabine correlating with change in LINE1 methylation (r = 0.47, P <0.15). While SLC19A1 methylation did not correlate with RFC1 scores, there was a trend towards an inverse correlation between change in SLC19A1 methylation and change in RFC1 expression (r = −0.45, P = 0.19).

Conclusions

In conclusion, after decitabine administration, there was increased expression of some (but not other) transporters that may play a role in chemotherapy uptake. Larger patient numbers will be needed to define the extent to which this increased expression is associated with changes in DNA methylation.

Emerging biological treatments for uterine cervical carcinoma

Cervical cancer is the third most common cancer worldwide, and the development of new diagnosis, prognostic, and treatment strategies is a major interest for public health. Cisplatin, in combination with external beam irradiation for locally advanced disease, or as monotherapy for recurrent/metastatic disease, has been the cornerstone of treatment for more than two decades. Other investigated cytotoxic therapies include paclitaxel, ifosfamide and topotecan, as single agents or in combination, revealing unsatisfactory results. In recent years, much effort has been made towards evaluating new drugs and developing innovative therapies to treat cervical cancer. Among the most investigated molecular targets are epidermal growth factor receptor and vascular endothelial growth factor (VEGF) signaling pathways, both playing a critical role in cervical cancer development. Studies with bevacizumab or VEGF receptor tyrosine kinase have given encouraging results in terms of clinical efficacy, without adding significant toxicity. A great number of other molecular agents targeting critical pathways in cervical malignant transformation are being evaluated in preclinical and clinical trials, reporting preliminary promising data.

In the current review, we discuss novel therapeutic strategies which are being investigated for the treatment of advanced cervical cancer.

5-Aza-2'-deoxycytidine enhances maspin expression and inhibits proliferation, migration, and invasion of the bladder cancer T24 cell line

BACKGROUND

Downregulation of maspin expression has been linked to bladder cancer development, and that DNA methylation may be important for regulating maspin gene activation in bladder cancer cells. Thus, we attempted to explore the effects of the DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine (5-Aza-CdR), on the maspin expression and the biological behaviors in bladder cancer T24 cells.

METHOD

The methylation status of maspin in T24 cells was investigated by methylation-specific polymerase chain reaction (PCR). After treated with different concentrations of 5-Aza-CdR (0, 0.25, 0.5, 1, and 2 μM), the maspin gene mRNA expression and protein expression were examined by real-time PCR and western blotting analysis. Cell proliferations were evaluated by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. Flow cytometry was used to identify the apoptosis rates. Migration and invasive ability were determined by the transwell assay. Using the western blotting analysis, the changes of Cyclin D1, VEGF-C, VEGFR-3, MMP-2, MMP-9, caspase-3 p17, Bax, and Bcl-2 expression were measured.

RESULTS

Promoter DNA methylation of maspin was observed in T24 cells. The expression levels of maspin mRNA and protein in T24 cells were increased in a dose manner after treatment with increasing 5-Aza-CdR (p<0.05). The proliferation, migration, and invasion of cells were significantly inhibited with increasing 5-Aza-CdR, whereas the apoptosis was greatly increased (p<0.05). These were associated with the decreased ratio of Bcl-2/Bax, activation of caspase-3, and decreased expression of Cyclin D1, VEGF-C, VEGFR-3, MMP-2 and MMP-9.

CONCLUSIONS

The present study demonstrates that maspin is silenced by DNA methylation in bladder T24 cells, and its expression can be reactivated by treatment with 5-Aza-CdR. 5-Aza-CdR could result in obvious inhibitions of the proliferation, migration, and invasion of T24 cells, which may serve as a potential strategy for the treatment of bladder cancer.