Enhanced efficacy and specificity of epithelial ovarian carcinogenesis by embedding a DMBA-coated cloth strip in the ovary of rat

Nanocurcumin preserves kidney function and haematology parameters in DMBA-induced ovarian cancer treated with cisplatin via its antioxidative and anti-inflammatory effect in rats

CONTEXT

Cisplatin, as a first-line treatment for ovarian cancer, is associated with debilitating adverse effects, including nephrotoxic and haematotoxic effects.

OBJECTIVE

This study determines whether nanocurcumin, combined with cisplatin, would give additional benefit to kidney function and haematological parameters in rats with ovarian cancer.

MATERIALS AND METHODS

Twenty-five Wistar rats were divided into five untreated rats and 20-dimethylbenz(a)anthracene (DMBA)-induced ovarian cancer rats. The 20 ovarian cancer rats were divided into four treatment groups: vehicle, cisplatin, cisplatin-curcumin, and cisplatin-nanocurcumin. Cisplatin was given at the dose of 4 mg/kg BW once weekly, while curcumin or nanocurcumin was administered at 100 mg/kg BW daily for four weeks. At the end of treatment, we analysed kidney function, haematological parameters, and inflammatory and oxidative stress markers from plasma.

RESULTS

Nanocurcumin alleviates the increase in kidney function markers and abnormalities in haematological indices in rats treated with cisplatin. Compared to cisplatin-treated rats, plasma urea levels decreased from 66.4 to 47.7 mg/dL, creatinine levels lowered from 0.87 to 0.82 mg/dL, and neutrophil gelatinase-associated lipocalin (NGAL) levels declined from 8.51 to 3.59 mIU/mg protein. Furthermore, the therapy increased glutathione activities (from 2.02 to 3.23 U/µL), reduced lipid peroxidation (from 0.54 to 0.45 nmol/mL), and decreased plasma TNF-α (from 270.6 to 217.8 pg/mL).

CONCLUSIONS

Cisplatin with nanocurcumin in an ovarian cancer rat model may provide additional benefits as a preventive agent against renal impairment and cisplatin-induced haematological toxicity. However, further research is required to prove that using nanocurcumin for a more extended time would not affect its anticancer properties.

Optimization of 7,12-dimethylbenz(a)anthracene-induced rat epithelial ovarian tumors

Ovarian carcinoma is the second most common malignant tumor of the female reproductive system and an notable cause of cancer death. The detection and diagnosis of early ovarian carcinomas are still clinical challenges, which calls for imaging studies using early ovarian carcinoma animal models. The present study aimed to optimize the 7,12-dimethylbenz(a)anthracene (DMBA)-induced model of rat ovarian tumors by investigating the delivery methods, induction dose and time of DMBA exposure, and explored the morphological features of tumors using MRI. Three schemes were performed. In scheme one the ovary was covered with absorbable hemostatic gauze loaded with a high concentration of liquid DMBA. For this scheme, 150 Sprague-Dawley rats were divided into three groups depending on the DMBA dose (1.0, 2.0 and 3.0 mg). In scheme two DMBA solution was injected under the ovarian capsule. For this scheme, 159 rats were divided into 0.5, 1.0 and 1.5 mg DMBA groups. In scheme three the ovary was covered with absorbable gauze loaded with a high concentration of solid DMBA. For this scheme 161 rats were divided into 1.0, 2.0 and 3.0 mg DMBA groups. Each group of the three schemes was further subdivided into 60-, 90-, 120-, 150- and 180-day groups. In scheme two, the tumor formation rate was 75.6% (99/131), which was the highest in the 1.5 mg group (86.4%, 38/44) and reached 100% (10/10) on day 120. The induced tumors were serous in 93.9% (93/99) of tumors. Borderline ovarian tumors accounted for 19.2% (19/99) of all tumors, and ovarian cancer accounted for 46.5% (46/99). The mean maximum diameter (MMD) of borderline ovarian tumors was 10.29±3.41 mm, and that of ovarian cancer was 15.19±7.10 mm. MMD of the solid components increased with increasing malignancy. Cystic, cystic-solid and solid tumors were observed. The ovarian subcapsular injection of 1.5 mg DMBA was the best scheme for the rat ovarian tumor model. The present model is ideal for investigating the occurrence, development and imaging of ovarian tumors.

Perfusion-based functional magnetic resonance imaging for differentiating serous borderline ovarian tumors from early serous ovarian cancers in a rat model

BACKGROUND

Differentiation of borderline tumors from early ovarian cancer has recently received increasing attention, since borderline tumors often affect young women of childbearing age who desire to preserve fertility. However, previous studies have demonstrated that non-enhanced magnetic resonance imaging (MRI) sequences cannot sufficiently differentiate these tumors.

PURPOSE

To investigate the value of dynamic contrast-enhanced MRI (DCE-MRI) and intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in differentiating serous borderline ovarian tumors (SBOT) from early serous ovarian cancers (eSOCA).

MATERIAL AND METHODS

Twenty SBOT and 20 eSOCA rat models were performed with DCE-MRI and IVIM-DWI at 3.0-T MR scanner. Qualitative and quantitative parameters of DCE-MRI were acquired and compared between two groups and correlated with the microvessel density (MVD). The receiver operating characteristic (ROC) curve analyses were conducted to determine their differentiating performances.

RESULTS

SBOTs presented significantly lower values of the initial area under the enhancement curve (iAUC), volume transfer constant (K^trans), and extracellular extravascular volume fraction (v_e) (P < 0.05) and a significantly higher value of true diffusion (D) (P = 0.001) compared with eSOCAs. The diagnostic effectiveness of v_e combined with D was significantly better than that of v_e or K^trans alone (P ≤ 0.039).

CONCLUSION

DCE-MRI may represent a promising tool for differentiating SBOTs from eSOCAs and may not be replaced by IVIM-DWI. Combining DCE-MRI with DWI may improve the diagnostic performance of ovarian tumors.

Imatinib mesylate does not counteract ovarian tissue fibrosis in postnatal rat ovary

Chemotherapy may result in ovarian atrophy, a depletion of the primordial follicle pool, diminished ovarian weight, cortical and stromal fibrosis. Imatinib mesylate is an anticancer agent that inhibits competitively several receptor tyrosine kinases (RTKs). RTKs play important roles in cell metabolism, proliferation, and apoptosis. In clinic, imatinib mesylate is also known as an anti-fibrotic medicine. In the present study, the impact of imatinib on the ovarian tissue was investigated by assessing ovarian tissue fibrosis in postnatal rat administered with or without imatinib for three days. Fibrosis in the ovarian tissue was determined by histology (Picrosirius and Masson's trichrome staining) and the protein expression of vimentin and alpha-smooth muscle actin (α-SMA). Furthermore, mRNA expression of Forkhead box transcription factor O1 and O3 (FOXO1 and FOXO3), which are markers of cell proliferation was quantified. A short-term exposure to imatinib showed to increase tissue fibrosis in ovaries. This was observed by Masson's trichrome staining. Exposure to imatinib led also to a down-regulation of vimentin protein expression and up-regulation mRNA expression of FOXO3. This may indicate a role of FOXO3 in ovarian tissue fibrosis in postnatal rat ovaries.

A rat model of serous borderline ovarian tumors induced by 7,12-dimethylbenz[a]anthracene

Serous borderline ovarian tumors (SBOTs) behave between benign cystadenomas and carcinomas, and the effective detection and clinical management of SBOTs remain clinical challenges. Because it is difficult to isolate and enrich borderline tumor cells, a borderline animal model is in need. 7,12-dimethylbenz[a]anthracene (DMBA) is capable of inducing the initiation, promotion, and progression of serous ovarian tumors. This study aims to investigate the proper dosage and induction time of DMBA for rat models of SBOTs, and explore their morphological features demonstrated by magnetic resonance (MR) imaging and molecular genetic characteristics. Rats were randomly divided into six groups (1 mg/70 D, 2 mg/70 D, 3 mg/70 D, 2 mg/50 D, 2 mg/90 D, and 2 mg/110 D). The 3 mg/70 D group induced the most SBOTs (50.0%, 12/24). The micropapillary projections were shown on MR imaging, which was the characteristic of SBOTs. The Cyclin D1 characterizing an early pathogenetic event strongly expressed in induced serous benign tumors (SBTs). The immunoreactivity staining scores of P53 expression significantly increased from SBTs, SBOTs to serous ovarian carcinomas (SCAs), which elucidate that P53 might be a promising biomarker to grade serous ovarian tumors. Based on morphological and molecular genetic similarities, this rodent SBOT model was suitable for investigating the pathogenesis of serous ovarian tumors and developing an early detection strategy.

Preventative effect of celecoxib in dimethylbenz[a]anthracene-induced ovarian cancer in rats

PURPOSE

The present study investigated the preventive effect of the cyclooxygenase (COX)-2 inhibitor, celecoxib, in 7,12-dimethylbenz[a]anthracene (DMBA)-induced ovarian cancer in a rat model.

METHODS

A diet containing celecoxib (1500 ppm) was started 2 weeks before the introduction of DMBA. DMBA-soaked cotton threads were surgically applied to induce ovarian cancer in female Wistar rats. Tumor growth and survival were observed for 24 weeks.

RESULTS

During the study period, an overall tumor incidence of 97.5% was observed and 65% of tumors were ovarian adenocarcinoma. The celecoxib diet significantly reduced the incidence and size of DMBA-induced ovarian cancers and significantly improved survival of tumor-bearing rats. The preventive effect of celecoxib was associated with increased apoptosis.

CONCLUSION

DMBA-induced ovarian cancer in rats recapitulates many pathophysiological features of the human counterpart. Our results provide supportive evidence that celecoxib has a preventive effect on development of ovarian cancer in a rat model.

The value of DCE-MRI in assessing histopathological and molecular biological features in induced rat epithelial ovarian carcinomas

Background

To investigate dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) for assessing histopathological and molecular biological features in induced rat epithelial ovarian carcinomas (EOCs).

Methods

7,12-dimethylbenz[A]anthracene (DMBA) was applied to induce EOCs in situ in 46 SD rats. Conventional MRI and DCE-MRI were performed to evaluate the morphology and perfusion features of the tumors, including the time-signal intensity curve (TIC), volume transfer constant (K^trans), rate constant (K_ep), extravascular extracellular space volume ratio (V_e) and initial area under the curve (IAUC). DCE-MRI parameters were correlated with histological grade, microvascular density (MVD), vascular endothelial growth factor (VEGF) and fraction of Ki67-positive cells and the serum level of cancer antigen 125 (CA125).

Results

Thirty-five of the 46 rats developed EOCs. DCE-MRI showed type III TIC more frequently than type II (29/35 vs. 6/35, p < 0.001) in EOCs. The two types of TIC of tumors had significant differences in the histological grade, MVD, expression of VEGF and Ki67, and the serum level of CA125 (all p < 0.01). K^trans, K_ep and IAUC values showed significant differences in different histological grades in overall and pairwise comparisons except for IAUC in grade 2 vs. grade 3 (all p < 0.01). There was no significant difference in V_e values among the three grade groups (p > 0.05). K^trans, K_ep and IAUC values were positively correlated with MVD, VEGF and Ki67 expression (all p < 0.01). V_e was not significantly correlated with MVD, VEGF expression, Ki67 expression and the CA125 level (all p > 0.05).

Conclusions

TIC types and perfusion parameters of DCE-MRI can reflect tumor grade, angiogenesis and cell proliferation to some extent, thereby helping treatment planning and predicting prognosis.

Vitamin D postpones the progression of epithelial ovarian cancer induced by 7, 12-dimethylbenz [a] anthracene both in vitro and in vivo

Purpose

Ovarian cancer is the most lethal malignancy of the female reproductive system, and the prevention and treatment of ovarian carcinoma are still far from optimal. Epidemiological studies reported that ovarian cancer risk was inversely associated with low level of 25-hydroxy vitamin D [25(OH)]. Therefore, this study focuses on exploring the chemoprevention of vitamin D on epithelial ovarian cancer induced by 7, 12-dimethylbenz [a] anthracene (DMBA).

Methods

The mouse ovarian surface epithelial cells were isolated from estrus mice by mild trypsinization and maintained in completed culture medium by repeated passaging. The malignant transformation of mouse ovarian surface epithelial cells was induced by DMBA in vitro. DMBA was directly injected into the bursa of mouse ovary to produce optimized in vivo ovarian cancer model.

Results

The results indicate that 1α,25 dihydroxyvitamin D3 may delay malignant transformation of mouse ovarian surface epithelial cells induced by DMBA and significantly decreased the colony formation rate from 18.4% to 3.2% (P<0.05). There was a negative correlation between incidence of DMBA-induced tumor and 25-hydroxy vitamin D level (R²=0.978, P<0.05). Vitamin D3 can delay the progression of ovarian cancer induced by DMBA, and the administration of vitamin D3 during the whole process worked more effectively than the administration only during tumor initiation or promotion. Moreover, we found the vitamin D3 increased the expression of E-cadherin and vitamin D receptor while it decreased the expression of β-catenin.

Conclusion

We succeeded in establishment of epithelial ovarian cancer models both in vitro and in vivo. The DMBA-implanted model in mice yields high incidence and specificity of epithelial derived tumors. We also found that vitamin D delays the progression of ovarian cancer. However, spontaneous epithelial ovarian carcinoma models are still to be explored for testing the preventive effects of vitamin D on epithelial ovarian cancer.

Characterization of chemically induced ovarian carcinomas in an ethanol-preferring rat model: influence of long-term melatonin treatment

Ovarian cancer is the fourth most common cause of cancer deaths among women, and chronic alcoholism may exert co-carcinogenic effects. Because melatonin (mel) has oncostatic properties, we aimed to investigate and characterize the chemical induction of ovarian tumors in a model of ethanol-preferring rats and to verify the influence of mel treatment on the overall features of these tumors. After rats were selected to receive ethanol (EtOH), they were surgically injected with 100 µg of 7,12-dimethyl-benz[a]anthracene (DMBA) plus sesame oil directly under the left ovarian bursa. At 260 days old, half of the animals received i.p. injections of 200 µg mel/100 g b.w. for 60 days. Four experimental groups were established: Group C, rats bearing ovarian carcinomas (OC); Group C+EtOH, rats voluntarily consuming 10% (v/v) EtOH and bearing OC; Group C+M, rats bearing OC and receiving mel; and Group C+EtOH+M, rats with OC consuming EtOH and receiving mel. Estrous cycle and nutritional parameters were evaluated, and anatomopathological analyses of the ovarian tumors were conducted. The incidence of ovarian tumors was higher in EtOH drinking animals 120 days post-DMBA administration, and mel efficiently reduced the prevalence of some aggressive tumors. Although mel promoted high EtOH consumption, it was effective in synchronizing the estrous cycle and reducing ovarian tumor mass by 20%. While rats in the C group displayed cysts containing serous fluid, C+EtOH rats showed solid tumor masses. After mel treatment, the ovaries of these rats presented as soft and mobile tissues. EtOH consumption increased the incidence of serous papillary carcinomas and sarcomas but not clear cell carcinomas. In contrast, mel reduced the incidence of sarcomas, endometrioid carcinomas and cystic teratomas. Combination of DMBA with EtOH intake potentiated the incidence of OC with malignant histologic subtypes. We concluded that mel reduces ovarian masses and the incidence of adenocarcinomas in ethanol-deprived rats.