Case Analysis Of Canine Mammary Tumor In Wuhan And Study On The Mechanism Of DTX Inhibiting Vascular Growth Of Breast Tumor

The incidence and malignancy rate of canine mammary tumors(CMTs)is high,and its clinical treatment is mainly surgical resection,which leads to the short survival period and poor quality of life of dogs with malignant CMTs.Therefore,it is necessary to explore new therapeutic means to prolong their survival period and improve their quality of life.Docetaxel is the first generation of taxanes,which anti-cancer effect is stable and has been used in human medicine for a long time.Studies have confirmed that DTX can not only kills tumor cells,but also inhibits tumor angiogenesis.Blood vessels play a key role in the development of tumor.Vascular endothelial growth factor A(VEGF-A),hypoxia-inducible factor-1α(HIF-1α)and matrix metalloproteinase-9(MMP-9)play an important role in tumor angiogenesis.Microvascular density(MVD)and vascular maturation index(VMI)can indicate tumor angiogenesis.There are few studies that explore the effect of DTX on angiogenesis of CMTs.Therefore,the purpose of this study is to explore the application prospect of antiangiogenic drugs in CMTs and the effect of DTX on CMTs angiogenesis,analyze the feasibility of DTX as an anti-angiogenic drug in clinical application,and provide a new idea for the treatment and drug development of CMTs.Methods:(1)Collecting clinical cases to carry out epidemiological investigation of CMTs and summarize the main process of treatment of CMTs in Veterinary Hospital in Wuhan.Collecting tumor tissues,carrying out immunofluorescence double staining of platelet-endothelial cell adhesion molecule(PECAM-1/CD31)and α-smooth muscle actin(α-SMA)to calculate MVD and VMI to express CMTs angiogenesis.(2)We establish the transplanted tumor model of CMTs mice and inject different doses of DTX intraperitoneally for 24 days(2mg/kg,4mg/kg,8mg/kg).Examining the exfoliated tumor tissue by real-time fluorescence quantitative PCR(q PCR),immunohistochemistry(VEGF-A,HIF-1α and MMP-9)and immunofluorescence double staining(CD31 and α-SMA).Analyzing the experimental data to reveal the effect of DTX on angiogenesis of CMTs.Results:(1)The malignant rate of CMTs in Wuhan animal hospitals reaches 54.8%,and the malignant rate is relatively high.Purebred dogs account for 59.7% of CMTs patients in Wuhan;the age of onset ranges from 9 to 12 years old account for 69.7%;unsterilized patients account for 76.8%;carcinoma-mixed type(8/45),comedocarcinoma(8/45)and squamous cell carcinoma(7/45)are more common in malignant CMTs,and ductal adenomas(10/37),complex adenomas(9/37)and benign mixed tumors(7/37)are more common in benign CMTs.At present,surgical resection is the main treatment for CMTs in Wuhan animal hospitals;B-ultrasound and CT are used to explore the tumor range,assist operation and improve the cure rate.Taking a case as a representative to summarize a relatively standardized process of diagnosis and treatment of CMTs.The average MVD of normal canine mammary gland tissues,benign CMTs and malignant CMTs are 25.00,32.25 and 79.13 respectively.The mean values of VMI in normal canine mammary gland tissues,benign CMTs and malignant CMTs are 0.80,0.67 and 0.31;the mean values of MVD and VMI in malignant CMTs are significantly different from those in normal mammary tissues and benign CMTs(P< 0.01).(2)DTX can inhibit the growth of tumor in tumor-bearing mice;the volume and weight of transplanted tumor decrease after intraperitoneal injection of DTX,and the antitumor effect is significantly different with the increase of dose;the volume and weight of transplanted tumors are the smallest when the maximum dose of DTX(8mg/kg)is injected intraperitoneally.With the increase of DTX dose,the m RNA and protein expression levels of VEGF-A,HIF-1α and MMP-9in transplanted tumors decrease at first and then increase,and the expression level is the lowest at 4mg/kg.With the increasing of the dose of DTX,the MVD of the transplanted tumors decrease at first and then increase,while the VMI increase at first and then decrease.The best dose of DTX to inhibit tumor angiogenesis is 4mg/kg,and no damage in primary organ(heart,liver,spleen,lung,kidney)is found while the dose of DTX is8mg/kg.Conclusion: The malignant rate of CMTs is high,and the angiogenesis ability of malignant CMTs is strong.The current clinical treatment of CMTs is difficult to meet the clinical needs,and anti-angiogenesis drugs can be applied to treatment for CMTs.DTX can inhibit the angiogenesis of CMTs,and then inhibit the growth and metastasis of the CMTs.Its safety and effectiveness are good,which is expected to be an anti-angiogenic drug for malignant CMTs treatment.