Ciência e terapia do câncer

Background: Breast and ovarian cancer are the most common cancers among hetrogenetically diversified women. It is quite difficult to categorize the population at a high risk of breast cancer using peer genetic information because one particular mutation can be found in the same or in different families. Several mutations have been discovered across the full length of BRCA1 gene, and categorizing their pathogenicity is a major challenge. Carriers of BRCA1 mutations have an increased risk of developing cancer. In the breast cancer database BIC, approximately 1,500 genetic variants have been reported. It is very difficult to characterize each of the reported mutations. Given the complexities in characterizing the mutations, we decided to investigate functional basis associated with the mutations, rather than looking at each mutation.

Materials and methods: BRCA1 BRCT domains were cloned, expressed, and purified using e-coli bacterial expression system. Mutations were generated using site-directed mutagenesis techniques, and all the mutations were sequence verified. The secondary structure of the mutant was characterized by Circular dichroism (CD) and Fluorescence spectroscopy. Molecular dynamics simulations were performed using Desmond software. Hydrophobic interactions and hydrogen bonding of docked molecules were compared using the LigPlot program.

Results: Genetic mutations were discovered throughout BRCA1, and most of the pathogenic mutations were buried in the hydrophobic core and destabilized the BRCA1 BRCT domain. This unstable BRCT domain destabilized the full-length BRCA1, resulting in a loss of function. We conclude that the pathogenicity of each of the mutations in the BRCT domain can be categorized on the basis of its ability to destabilize the hydrophobic interactions. Although such instability is not sufficient to predispose someone to cancer, it provides a basis for formulating a concept for genetic counseling and targeted therapy.

The purpose of this study is to check the similarities of differential gene expression of 11 genes in breast cancer tissue and blood samples from the same individual for early detection of breast cancer. We had investigated differential gene expression by qRT-PCR in 20 breast cancer patients’ tumoral tissues and corresponding blood sample. In our analysis BRCA2, HER-2, ER, PR, MET and BRAF mRNA levels were significantly over expressed in tumoral tissues. ER and PR mRNA levels were not detected in any of the peripheral blood samples, whereas KRAS and PTEN mRNA levels were not detected in any of the tumoral tissues. HER-2 (45%), EGFR (40%) and PI3KCA (30%). KRAS and PTEN mRNA levels were significantly over expressed in peripheral blood. In the correlation analysis expression of most of the genes were significantly altered in grade II and III in the tissues, where as in premenopausal women mRNA expression was significantly high in Grade II and III and ER/PR negative tumors. Our results suggests that BRCA2, ER, PR, PI3KCA, MET and BRAF differential gene expression at mRNA levels showed no diagnostic value as a marker of circulating tumour cells in breast cancer. qRT-PCR may be suitable alternative method for the determination of HER-2, EGFR, PI3KCA KRAS and PTEN mRNA status in the blood of breast cancer patients. Premenopausal women with high grade (Grade II and III) and ER/PR negative cases may be associated with proliferation/metastasis, high recurrence rate, and poor prognosis.

Cisplatin is one of the most widely used anti-cancer drugs due to its ability to damage DNA and induce apoptosis. However, increasing reports of side effects and drug resistance indicate the limitation of cisplatin in cancer therapeutics. Recent studies showed that inhibition of gap junctions diminishes the cytotoxic effect and contributes to drug resistance. Therefore, identification of molecules that counteract gap junctional inhibition without decreasing the anti-cancer effect of cisplatin could be used in combinational treatment, potentiating cisplatin efficacy and preventing resistance. This study investigates the effects of combinational treatment of cisplatin and PQ1, a gap junction enhancer, in T47D breast cancer cells. Our results showed that combinational treatment of PQ1 and cisplatin increased gap junctional intercellular communication (GJIC) as well as expressions of connexins (Cx26, Cx32 and Cx43), and subsequently decreased cell viability. Ki67, a proliferation marker, was decreased by 75% with combinational treatment. Expressions of pro-apoptotic factors (cleaved caspase-3/-8/-9 and bax) were increased by the combinational treatment with PQ1 and cisplatin; whereas, the pro-survival factor, bcl-2, was decreased by the combinational treatment. Our study demonstrates for the first time that the combinational treatment with gap junction enhancers can counteract cisplatin induced inhibition of gap junctional intercellular communication and reduction of connexin expression, thereby increasing the efficacy of cisplatin in cancer cells.

Cancer cells continue to grow and divide, without undergoing apoptosis. p53, a tumor suppressor protein, serves as a checkpoint in prevention of cancer by inducing the abnormal cells to commit apoptosis. p53 can induce both extrinsic and intrinsic pathways of apoptosis and can also induce apoptosis by directly acting on mitochondria. Regulation of p53 concentration in cell is very critical and is regulated by Mdm2 which triggers degradation through ubiquitinylation. Keeping in view, the role of p53 in preventing cancer, many effective strategies can be developed to combat cancer by enhancing either function or stability of p53.

Background: Inflammatory breast cancer (IBC) is an aggressive type of breast cancer disease that has a high incidence in Egypt than western countries. It is characterized by rapid progression, involvement of dermal lymphatic emboli and extensive lymph node involvement. Basic and translational studies are needed to define IBC disease biology and identify specific biomarkers have been limited by the paucity of patient samples. Hence, the current study aimed to introduce the telomerase activity level as a novel diagnostic marker for breast cancer and specifically for IBC to be differentiated from non-IBC.
 
Methods: Breast cancer patients were enrolled from Ain Shams University hospitals in Cairo, divided into two groups: IBC (n=26) and non-IBC (n=27). Tissue samples were collected during modified radical mastectomy. TRAP (Telomerase repeat amplification protocol) assay was used to assess the telomerase activity in inflammatory and non inflammatory breast cancer tissue samples. Immunohistochemistry was used to investigate the expression of hTERT subunit of telomerase in paraffin embedded tissue samples of both types of patients.
 
Results: IBC showed Telomerase activity ranged from 12.2 to 367.1 units with a mean value of 78 and a median value of 43, while telomerase activity in non-IBC ranged from 6.1 to 109.34 units with a mean value of 41.1 and a median value of 24. On the other hand, normal tissues showed telomerase activity below 5 (P<0.001). Using immunohistochemistry, the hTERT expression was higher in IBC than non-IBC and no expression at all in normal tissues. Moreover, a positive mild correlation was found between the telomerase activity and the number of metastatic lymph nodes in both IBC (r=0.53) and non-IBC (r=0.54).
 
Conclusions: Telomerase could be a promising marker at the diagnostic and therapeutic levels in breast cancer and specifically in IBC.

Objective: Severe acute radiation-induced skin reactions occur in a significant proportion of women who receive radiation therapy for breast cancer. We previously showed that Mepilex Lite dressings decreased the severity of erythema. Here we report their effect on the full range of skin reactions in 74 breast cancer patients post-mastectomy.
 
Methods: A total of 80 women were recruited from four hospitals in New Zealand with 74 women contributing a full data set for analysis. The first skin area on the chest wall to develop erythema was randomly divided into two similar halves; one half was treated with Mepilex Lite dressings, the other half with aqueous cream. Skin reactions were assessed using the Radiation-Induced Skin Reaction Assessment Scale.
 
Results: Compared with aqueous cream, Mepilex Lite dressings did not significantly reduce the incidence of moist desquamation but did reduce the overall severity of skin reactions by 41% (p<0.001), the average moist desquamation score by 49% (p=0.043) and the sum of the moist desquamation time for all patches by 28% from 25 to 18 weeks. Most patients preferred the dressings, found them easy to use and very comfortable to wear.