[Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) Contributes to Tamoxifen Resistance in Estrogen-Positive Breast Cancer Patients]

Crosstalk between the estrogen receptors and the receptor tyrosine kinases, including vascular endothelial growth factor receptor type II (VEGFR2), is a key mechanism in breast cancer resistance to antiestrogen therapy with tamoxifen. A high level of VEGFR2 expression in a tumor serves as a marker of tamoxifen resistance. The tamoxifen efficacy prognostic value of functional polymorphisms in the VEGFR2/KDR gene has not been established. Using qRT-PCR, we detected the rs2071559 and the rs2305948 variants and the levels of KDR gene expression in 122 breast tumor tissue samples from cohorts of patients with progression (distant metastases or relapse) and patients with no progression during tamoxifen therapy. The expression levels of VEGFR2 protein were analyzed by immunohistochemistry. The frequency of heterozygous and mutant genotypes of the rs2305948 SNP was significantly higher in patients without progression than in the cohort with progression. KDR rs2305948 was associated with high survival rates in breast cancer patients. A correlation between the mRNA of the ESR1 and KDR genes in patients without progression was detected. The results indicate the prognostic value of rs2305948 and its potential contribution to the tumor phenotype sensitive to tamoxifen.

Changes in the Activity of Proteasomes and Calpains in Metastases of Human Lung Cancer and Breast Cancer

In patients with breast cancer and lung cancer, chymotrypsin-like and caspase-like activities of proteasomes and total activity of calpains in the primary tumor nodes and lymphogenic metastasis are elevated in comparison with the corresponding normal tissues. The development of lymphogenic metastases of breast cancer and lung cancer was associated with opposite change in caspase-like activity of proteasomes. These results can be useful for the development of methods for evaluation of aggressiveness of breast and lung cancer.

[Transcription factors NF-kB, HIF-1, HIF-2, growth factor VEGF, VEGFR2 and carboanhydrase IX mRNA and protein level in the development of kidney cancer metastasis]

Here, we have investigated the participation of nuclear factors NF-kB, HIF-1 and HIF-2, VEGF, VEGFR2, and carboanhydrase IX in clear-cell renal cancer. We have determined the expression and protein level of transcription factors, VEGF, VEGFR2, and carboanhydrase IX in tumor and normal tissues of 30 patients with kidney cancer. The Real-Time PCR and ELISA were used in the study. The low levels of HIF-1 mRNA expression associated with high levels of HIF-1 protein were also associated with metastasis. The expression levels of VEGF, VEGFR2, and their protein levels are increased in primary tumors of patients with disseminated kidney cancer compared to nonmetastatic cancer. No correlation was revealed between the content of mRNA and encoded proteins in the kidney cancer tissues. The changes in the ratios of mRNA levels and the respective proteins (HIF-1α, HIF-2, NF-kB, VEGF, VEGFR2, and carboanhydrase IX) may contribute to kidney-cancer metastasis.

[Activation of AKT of signaling pathway and the level of mTOR substrates in tumor of patients with kidney cancer, connection with prevalence of malignancy]

Activation of AKT signaling pathway and mTOR substrates of kidney tumor tissue occurs by improving AKT, its phosphorylated form, the serine / threonine proteinkinase m-TOR, the exchange regulator glycogen GSK-3-beta and also the inhibitor of 4E-BP1transcription. Increasing the size of primary tumor is followed by increasing the content of therein c-Raf and decreasing the content of phospho-m-TOR. The development of disseminated forms of the disease was associated with a reduction PTEN and phospho-AKT in tumor.

[Ethnic aspects of hereditary breast cancer in the region of Siberia]

BACKGROUND

Ethnic diversity of the population in the region of Siberia suggests the existence of different germline mutations in the BRCA1/2 genes associated with breast and ovarian cancer in different ethnic populations, but spectrum of these mutations has not been studied.

OBJECTIVE

Our aim was to evaluate the frequency of the most common mutations BRCA1/2 (BRCA1 5382insC, BRCA1 185delAG, BRCA1 4153delAG, BRCAI T300G, BRCA2 6174delT) in women diagnosed with breast cancer among indigenous people and newcomers living in Siberia.

METHODS

We tested 1281 genomic DNA samples for the presence of BRCA1 5382insC mutation in patients diagnosed with breast cancer considering no family history. 72 patients having hereditary cancer signs were tested for the mutations BRCA1 185delAG, BRCA1 4153delAG, BRCA1 T300G, BRCA2 6174delT.

RESULTS

Out of 765 patients of Slavic ethnic group, 27 women (3.5%) were carriers of allele BRCA1 5382insC. The frequencies of mutations in patients with signs of hereditary cancer were: 8.3% in group of young patients (under 40 years), 20.0% in patients with bilateral cancer and 5.7% in patients with family history of breast or ovarian cancers. We tested 516 BC patients residing on the territory of the Buryat-Aginsky district, Republics of Tyva and Altai. Out of them, there were 197 patients among the indigenous population (buryats, tuvinians, altaians), and 319 patients among newcomers (Slavic ethnics). Mutations BRCA1 5382insC were detected only in women from Slavic ethnic groups. The frequency of BRCA1 5382insC mutation was 6% in the group where family history was excluded and 14% in the group of patients with characteristics of family cancer. Allele BRCA1 5382insC was not found in indigenous breast cancer patients, although 59 patients had signs of hereditary cancer. In women from Slavic ethnic group, the BRCA1 185delAG, BRCA1 4153delAG and BRCA1 T300G mutations were detected in 9.1% of cases and were not found in patients among the indigenous population.

CONCLUSION

studies of mutations in the BRCA1 gene in breast cancer patients from Siberia confirmed data on the high frequency of "founder mutation" BRCA1 5382insC in Slavic population and indicate the advisability of further studies to identify the genes responsible for the occurrence of hereditary breast cancer in the indigenous population.

[Chymotripsin-like activity and subunit composition of proteasomes in human cancers]

Activity of the proteasome, polyfunctional enzymatic complex, is known to undergo changes during cancer development. This phenomenon is, probably, caused by the changes in subunit composition of proteasomes. In present work, we studied chymotrypsin-like activity of proteasomes, subunit composition and their association in breast cancer, head and neck squamous cell carcinoma, endometrial cancer, renal cancer, bladder cancer, stomach cancer and colorectal cancer. The increase of proteasome activity was revealed in most cancer tissues compared with adjacent tissues except for the renal cell carcinoma. Changes in proteasome activity in cancer tissues compared with correspondent normal tissues were accompanied by modification of its subunit composition. High proteasome activity was observed in combination with an increased expression of immune subunits and/or proteasome activator PA28, associated with activity of 20S proteasome. In breast cancer, head and neck squamous cell carcinoma, bladder cancer, stomach cancer and colorectal cancer we additionally found higher expression of Rpt6 subunit of 26S proteasome. Correlations between chymotrypsin like proteasome activity and subunit expressions were found in human cancer tissues. In summary, we suggest that proteasome ac- tivation and changes in its subunit composition plays an important role in cancer pathogenesis.

Quantification of breast cancer blood flow in absolute units using Gjedde-Rutland-Patlak analysis of 99mTc-MIBI uptake

BACKGROUND

Scintimammography with 99mTc-MIBI has been proven as efficient technique of diagnosis of breast cancer. Nevertheless, quantification of breast carcinoma blood flow (BCBF) in absolute units is not yet developed. To compensate this, we analysed kinetics of 99mTc-MIBI uptake in breast cancer using Gjedde-Rutland-Patlak (GRP) approach.

METHODS

If BC is radioactivity in breast cancer quantified by dynamic scintigraphy, C(h)-blood concentration of 99mTc-MIBI and K-transport constant, then, assuming 99mTc-MIBI uptake to breast carcinoma unidirectional for early minutes after injection and subjected to equation d(BC)/dt = K; C(h), classic GRP plot can be obtained from this by integration as BC/C(h)=K x (integral of C(h)(dt))/C(h) + V0 and placing [(integral of C(h)(dt))/C(h)] as X, and (A/Ch) as Y. The K can be then obtained as slope. K is breast cancer clearance equal to product (retention fraction); (blood flow) : K = E; BCBF. K can be calculated from A(t) and Ch(t) as asymptote of 99mTc-MIBI retention function h(t) = F-1[F[A(t)]/F[Ch(t)]], where F depicts Fourier transforms. The BCBF can be then obtained as ratio K/E. We employed the technique in 33 patients with breast carcinoma of stages T(1-3)N(0-3)M(0-1) injecting 99mTc-MIBI (370-510 MBq) as i.v. bolus. In 12 scintigraphy with 99mTc-MAA (370 MBq) injected via catheter intraaortically was performed as validation study.

RESULTS

E values were essentially uniform over the population with overall mean 0.58 sd 0.06. Blood clearance curves did not differ between various stages also and were subjected to biexponential approximation. K was in all cases obtained from the slope of initial 3 min part of GRP plot, strongly linear (r > 0.95, p < 0.001) in all cases. 99mTc-MAA validation study revealed significant correlation with 99mTc-MIBI blood flow values (r = 0.94, p < 0.01). The BCBF(as ml/min/100 cm3) was in T1 12.85 sd. 4.76, in T2 15.87 sd. 1.78, in T3 17.35 sd. 2.45, and in T4 23.07 sd. 2.21, expressing tendency to increase with stage. Higher BCBF was significantly associated with metastatic spread and in patients with BCBF over 17 ml/min/100 cm3 distant mets were revealed in all cases.

CONCLUSION

Hence, analysis of early kinetics of 99mTc-MIBI in breast carcinoma provides correct estimates of blood flow in the neoplasm and can be applied in clinical studies and for calculation of cytostatic delivery to BC.