[Landscape of KRAS, BRAF, and PIK3CA Mutations and Clinical Features of EBV-Associated and Microsatellite Unstable Gastric Cancer].

Personalization of gastric cancer (GC) treatment is an urgent problem because of the clinical heterogeneity and aggressive course of the disease. Four GC subtypes were isolated based on molecular characteristics by The Cancer Genome Atlas researchers in 2014: Epstein-Barr virus positive (EBV^(+)), microsatellite unstable (MSI), chromosomally unstable (CIN), and genomically stable (GS). There is no unified method to detect the CIN and GS subtypes today, while MSI and EBV status assessments are used routinely and are of great clinical importance. A total of 159 GC samples were tested for MSI, EBV DNA, and somatic mutations in codons 12-13 (exon 2), 61 (exon 3), and 146 (exon 4) of the KRAS gene; codons 597-601 (exon 15) of the BRAF gene; and codons 542-546 (exon 9), 1047-1049 (exon 20) of the PIK3CA gene. EBV^(+) GC was detected in 8.2% of samples; and MSI, in 13.2%. MSI and EBV+ were found to be mutually exclusive. The mean ages at GC manifestation were 54.8 and 62.1 years in patients with EBV^(+) and MSI GCs, respectively. EBV^(+) GC affected men in 92.3% of cases, 76.2% of the patients were older than 50 years of age. Diffuse and intestinal adenocarcinomas were diagnosed in 6 (46.2%) and 5 (38.5%) EBV^(+) cases, respectively. MSI GC equally affected men (n = 10, 47.6%) and women (n = 11, 52.4%). The intestinal histological type was the most prevalent (71.4%); the lesser curvature was affected in 28.6% of the cases. The E545K variant of PIK3CA was observed in one EBV^(+) GC case. A combination of clinically significant variants of KRAS and PIK3CA was found in all MSI cases. The BRAF V600E mutation, which is specific to MSI colorectal cancer, was not detected. The EBV^(+) subtype was associated with better prognosis. The five-year survival rates were 100.0 and 54.7% for MSI and EBV^(+) GCs, respectively.

[Melanoma and Human Papillomaviruses: Is There an Outlook for Study?].

Melanoma is one of the most aggressive human malignant tumors. Its incidence and mortality are growing steadily. Ultraviolet irradiation is the main risk factor for melanoma involved in melanomagenesis. The probability of viral etiology of melanoma has been discussed. Human papillomaviruses (HPV) have been mentioned among candidates for its etiologic agents because some HPV types are the powerful carcinogens causing cervical cancer and other cancers. The review analyses the literature data on the association of melanoma with HPV Several groupsfound HPVin skin melanomas as well as in mucosa; viruses of high oncogenic risk were detected in some cases. For some organs the etiological role of high-risk HPV as inducers of invasive carcinomas is confirmed. These organs require special mention: cervix uteri, vulva, vagina, penis, anal region, and oral cavity. However in the majority of the studies in which viral DNA-positive melanomas were found, testing for viral genome expression was not done while this is the fact of primary importance. HPVare found in normal skin and mucous membranes thus creating justifiable threat of tumor specimen contamination with viral DNA in vivo. There are limited data on aggravation of the disease prognosis in papillomavirus-positive melanomas. However, any systematic observation of a sizeable patient group distinguished by that tumor type has not been performed yet. Viral E6 and E7 oncogenes of high-risk papillomaviruses were shown to be able to transform normal human melanocytes in vitro experiments. Thus, we can assume the presence of the association of melanoma with oncogenic HPV. The clinical significance of this problem is indisputable under the conditions of the steady increase in melanoma incidence and mortality rates in Russia and abroad. The problem requires further study.

Loss of Cell Differentiation in HPV-Associated Bladder Cancer.

Medical histories of 101 urothelial bladder cancer patients were compared with the results of morphological analysis and biomolecular detection of human papilloma viruses (HPV) in the tumor specimens. DNA of HPV16 (the major type of virus responsible for appearance of cervical carcinoma) was detected in 38 specimens, while mRNA of E6 and E7 oncogenes and E7 oncoprotein of HPV16 were observed in 13 specimens. HPV-positive bladder cancer was characterized by higher degree of cell anaplasia than HPV-negative cancer; in the primary bladder tumor, HPV was detected more often than in recurrent bladder cancer. These data attest to involvement of HPV16 in the genesis of bladder cancer. No correlations of HPV status of bladder tumor with patient's sex, age, and invasion into the muscle layer were revealed.

Complex of molecular genetic and immunohistochemical methods for detection of human papillomavirus in the bladder cancer epithelium.

A battery of tests for detection human papillomavirus DNA, mRNA corresponding to viral oncogenes, and viral oncoprotein E7 in cancer bladder urothelium was piloted in 35 samples of bladder cancer. DNA of human papillomavirus type 16 (causes cervical cancer) was found in 16 (46%) samples; E6/E7 oncogene transcript and E7 oncoprotein of human papillomavirus type 16 were detected in 10 and 7 human papillomavirus DNA-positive samples, respectively. These findings attest to association of bladder cancer with human papillomavirus in Russia.

Cellular expression of INK4a gene in cells of bladder cancer associated with human papilloma virus-16.

Hyperexpression of p16(INK4a) protein is an early marker of cervical cancer. Hyperexpression of INK4a gene encoding this protein at the level of mRNA and p16(INK4a) was detected in tumor cells of some patients with bladder cancer associated with human papilloma virus-16. However, in contrast to cervical cancer, this phenomenon in urothelial carcinomas does not correlate with expression of human papilloma virus-16 oncogenes E6 and E7.

[Are human papillomaviruses responsible for the occurrence of bladder cancer].

A female patient with recurrent bladder cancer underwent complex examination. The primary tumor removed in 2004 showed human papillomavirus (HPV) 16 DNA, mRNA corresponding to HPV16 oncogene E7, as well as HPV16 protein E7. The patient is a smoker who has been working at a chemical factory for over 20 years. During tumor recurrence in 2009, there was no DNA of high-risk HPV types in the cancer cells. HPV16 E7protein and cellular p 16(INK4alpha), an indicator of HPV-induced carcinogenesis, were not found. Colposcopy revealed no precancerous changes in the epithelium of the cervix uteri. The cervical epitheliocytes contained no high-risk HPV DNA, E7 and p16(INK4alpha) proteins. It seems expedient to continue in vitro studies of the possible role of HPV in urothelial carcinogenesis on an experimental model.

[Detection of oncoprotein E7 HPV16 in the cancer and normal urinary bladder urothelium].

Oncoprotein E7 HPV16 was detected by immunohistochemical staining with specific polyclonal antiserum [Fiedler et al., 2004] in 7 out of the 24 (29.2%) studied bladder cancer specimens. The result is in good agreement with the hypothesis that HPVs take part in the carcinogenesis of the urothelium. However, some of the observations made seem rather hard to be interpreted at present. The latter include the detection of E7 HPV16 in a small number of cancer cells in a few bladder cancer specimens being examined; the presence of this protein in the cytoplasm, rather in the cancer cell nuclei, and its detection in some morphologically normal bladder urothelial specimens from non-cancer patients. Thus, the hypothesis that HPVs are implicated in the carcinogenesis of the bladder urothelium deserves further verification.

STAT1 gene expression in cervical carcinomas.

Expression of the STAT1 gene belonging to the group of interferon-regulated genes was analyzed in cervical tumors and cell lines harboring the genome of human papilloma viruses (HPV) of so-called high risk group. Expression of this gene in invasive carcinomas was maintained on a definite level that was not significantly distinct from that in adjacent normal (control) tissue. Tumors from different patients differ from each other by expression level of the STAT1 gene. These variations can be attributed to the heterogeneity of tumor cell population and different ratio between normal and tumor cells, as well as to putative persistence of intra-individual variability of STAT1 expression in normal cell population. It was demonstrated that viral genome status (episomal or integrative) did not influence STAT1 gene transcription. In conclusion, these data demonstrate that the STAT1 gene is expressed in an individual and specific manner both in HPV-positive cervical tumors and cell lines harboring transforming genes of these viruses.

[Expression of p16INK4a in various cancer cells]. / Ekspressiia belka P16ink4a v kletkakh nekotorykh rasprostranennykh form raka.

The p16INK4a protein was detected by means of monoclonal antibodies to this protein in the cells of some carcinomas: that of the lungs (17 samples), urinary bladder (6 samples) and mammary gland (4 samples) as well as in the cells of three cell lines from of human uterine cervix carcinoma: SiHa (containing high risk HPV genome), C33A and HT3 (both HPV-negative but have RB mutations in RB gene). Lung carcinoma samples were very heterogenous by the part of cells expressing p16INK4a. High content of this protein was found in all 6 samples of transient cell urinary bladder carcinoma and in 1 sample of mammary gland ductal carcinoma. Cells of all three cell lines also contained p16INK4a. Thus, hyperexpression of this protein is not specific for only HPV-positive cancer of the uterine cervix. The protein presence in cancer cells seems to be an indicator of gene RB mutation or other disturbances of RB pathway.