Regulation of telomere homeostasis and genomic stability in cancer by N 6-adenosine methylation (m6A)

The role of RNA methylation on N ⁶-adenosine (m⁶A) in cancer has been acknowledged, but the underlying mechanisms remain obscure. Here, we identified homeobox containing 1 (HMBOX1) as an authentic target mRNA of m⁶A machinery, which is highly methylated in malignant cells compared to the normal counterparts and subject to expedited degradation upon the modification. m⁶A-mediated down-regulation of HMBOX1 causes telomere dysfunction and inactivation of p53 signaling, which leads to chromosome abnormalities and aggressive phenotypes. CRISPR-based, m⁶A-editing tools further prove that the methyl groups on HMBOX1 per se contribute to the generation of altered cancer genome. In multiple types of human cancers, expression of the RNA methyltransferase METTL3 is negatively correlated with the telomere length but favorably with fractions of altered cancer genome, whereas HMBOX1 mRNA levels show the opposite patterns. Our work suggests that the cancer-driving genomic alterations may potentially be fixed by rectifying particular epitranscriptomic program.

[Morphological findings in fatal cases of hantavirus cardiopulmonary syndrome. Report of 7 autopsies]

INTRODUCTION

Hantavirus cardiopulmonary syndrome (HCPS) is an acute infectious disease characterized by sudden cardiorespiratory failure and high mortality, caused by a RNA virus of the genus Hantavirus, family Bunyaviridae, 15% of Chilean cases have been detected in the Araucania Region.

OBJECTIVE

To determine in fatal cases of HCPS, clinical and morphological characteristics.

MATERIALS AND METHODS

Descriptive-retrospective analysis of seven fatal cases with postmortem study of HCPS, attended between 1997 and 2009 at the Hospital of Temuco, Chile.

RESULTS

Cases were young patients from rural areas, and presented as an illness of progressive respiratory failure, with leukocytosis, thrombocytopenia and bilateral interstitial pulmonary infiltrates. Main morphological findings were marked intersticial and intraalveolar pulmonary edema, with minimal epithelial injury and mononuclear cell intersticial infiltrate and mild edematous intersticial inflamatory process.

CONCLUSIONS

Epidemiological, clinical and laboratory background allow to suspect HCPS. In fatal cases, the autopsy makes possible to discard other similar pathologies and provide tissue for confirmation of the disease.

[Human papillomavirus genotyping of cervical uterine preneoplastic lesions in a high risk area]

BACKGROUND

The relationship between human papillomavirus (HPV) and uterine cervical cancer (UCC) is widely known and accepted.

AIM

To determine the frequency of genotypes of HPV in cervical preneoplastic lesions in a high risk area of UCC.

MATERIAL AND METHODS

Using a combination of PCR and Reverse Line Blot technique, 235 formalin fixed paraffin embedded samples, with diagnosis of low-grade squamous intraepithelial lesion (LSIL) or high-grade squamous intraepithelial lesion (HSIL) were genotyped.

RESULTS

HPV was detected in 61.2% of LSIL and 78.1% of HSIL. The main genotypes found were HPV 16, 18, 31, 45, 56 y 58. HPV 16 was the most common in both LSIL (18.1%) and HSIL (36.9%). HPV 16 or 18 were present in 25.1% and 47.1% of the LSIL and HSIL respectively. In both LSIL and HSIL, the predominant viral genotypes were those types classified as with a high oncogenic risk.

CONCLUSIONS

HPV genotypes 16, 18, 31, 45, 56 y 58 were the most common in our series. HPV 16 and 18, viral types with high oncogenic risk and included in commercial vaccines, were found in 25.1% and 47.1% of LSIL and HSIL, respectively.

[Diagnostic value of frozen section biopsy during surgery for breast lesions or neoplasms]

BACKGROUND

During the surgical treatment of breast neoplasms (benign or malignant), frozen section biopsy is frequently requested to assess the kind of lesion and determine the surgical margins.

AIM

To assess the diagnostic yield of frozen section breast biopsy.

MATERIAL AND METHODS

AH the pathological reports of frozen section biopsies and definitive biopsies of 337 women aged 26 to 88 years, operated for suspected breast neoplasms between 2002 and 2006, were reviewed. The sensitivity, specificity and predictive value of frozen section biopsy, were calculated using the definitive biopsy as the gold standard.

RESULTS

The definitive biopsy confirmed the presence of cancer in 290 women (86%). There were two false negative (0.59%) and no false positive frozen section biopsies for cancer detection. The sensibility for cancer detection was 99.3% and the specificity 100%. The positive predictive value was 100% and the negative predictive value 96.1%. The diagnosis of phyllodes tumor was missed by frozen section biopsy in three cases. The margins were informed in the 258 frozen section biopsies (79%) and in 59 cases (18%), these were positive for cancer.

CONCLUSIONS

Frozen section biopsy is useful and reliable for cancer detection and margin status assessment in breast cancer surgery.

[Detection and genotyping of human papillomavirus in biopsies of uterine cervical adenocarcinoma]

BACKGROUND

The genotyping of Human Papillomavirus (HPV) will improve knowledge about the local epidemiological association of this virus with adenocarcinoma.

AIM

To determine the frequency of HPV genotypes in biopsies of women with uterine cervical adenocarcinoma in a geographic region of Chile.

MATERIALS AND METHODS

Forty-one cervical biopsies with a pathological diagnosis of adenocarcinoma, corresponding to all women diagnosed with this cancer between 2002 and 2004, were analyzed. Viral gene Ll was amplified by PCRfor viral detection. HPV genotyping was carried out by a Reverse Line Blot technique.

RESULTS

Seventy one percent of biopsies were positive for HPV. The most common genotypes found were HPV 16 (61%), followed by HPV 18 (19.5%). Eighty seven percent of biopsies had a single HPV infection. Three patients had a multiple HPV infection. All of the latter were infected by HPV 16, associated with other three viral genotypes (45, 52 and 66). No low-risk HPV genotypes were found.

CONCLUSIONS

In this sample of biopsies, there was a high prevelence of HPV 16 and a low prevalence of HPV 18, which historically has been related to adenocarcinoma. The genotypes found correspond to those described in South America.

[Papillary carcinoma in a thyroglossal duct cyst: report of two cases]

Thyroglossal duct cyst is the most common congenital anomaly of thyroid gland development. However, papillary carcinoma is described only in 1-2% of cases and the clinical appearance is indistinguishable from a benign thyroglossal duct cyst. We report two females aged 15 and 27 years consulting for a cervical mass. In both, a solid cystic lesion was found and excised using the Sistrunk procedure. The biopsy disclosed a papillary carcinoma in both. The postoperative evolution of both patients was uneventful.

[Gene methylation patterns in digestive tumors]

BACKGROUND

The loss of tumor suppressor gene function damages the defensive mechanisms that protect the indemnity of genetic material. Promoter gene methylation is one of the inactivation mechanisms of suppressor genes.

AIM

To study the methylation pattern of a group of genes in biopsy samples of gastrointestinal tumors.

MATERIAL AND METHODS

Forty eight gastric, 25 gallbladder, 24 colon and 6 pancreas cancer biopsy samples were randomly selected. The methylation pattern of CDH1, FHIT, CDKN2A, APC and MLH1 genes, was studied using a specific polymerase chain reaction test for methylation. Demographic, morphological and follow up variables of patients bearing the tumors were also analyzed.

RESULTS

The general methylation frequency of CDH1, FHIT, CDKN2A, APC and MLH1 genes was 64.1, 56, 39.8, 18.1 and 34% respectively. In gastric cancer samples there was a correlation between APC gene methylation and well differentiated tumors; between CDH1 methylation and Lauren diffuse type and the presence of three or more metastasic lymph nodes; between FHIT, CDKN2A and CDH1 gene methylation and male gender. In less differentiated gallbladder tumors, the frequency of CDH1 methylation was higher. There was a tendency towards a lower survival in colon and gastric cancer when MLH1 (p =0.07) y CDKN2A (p= 0.06) were methylated, respectively.

CONCLUSIONS

An abnormal methylation pattern was associated with morphological features in gastric and gallbladder cancer and with a tendency towards a lower survival in colon and gastric cancer.

Detección y tipificación de virus papiloma humano en lesiones preneoplásicas del cuello uterino mediante PCR-RFLP

BACKGROUND

The association of different genotypes of human papilloma virus (HPV) with cervical cancer is well known. However, there is little information about their association with pre-cancerous lesions.

AIM

To assess the frequency of different HPV genotypes in pre cancerous cervical lesions.

MATERIAL AND METHODS

A cervical sample was obtained by cytobrush in 15 women with low grade lesions and 40 women with high grade lesions, subjected to conization by loop electrical excision procedure (LEEP). Detection and typification of HPV was done by polymerase chain reaction and restriction fragment length polymorphism.

RESULTS

All women were infected with HPV. Eighty five percent of samples were typified. A unique HPV subtype was found in 76% of women. Fourteen percent had an infection with multiple subtypes and in 10%, the viral genotype was not identified. The most common subtypes found were HPV 16, HPV 52 and HPV 53.

CONCLUSIONS

There is a high rate of infection with HPV with a high oncogenic risk among these women.

[Aneurysmal bone cyst of the maxilla. Report of one case]

Aneurysmal bone cysts are benign fibro osseous lesions, rarely present in maxillary region. We report the CT and morphological findings of aneurysmal bone cyst of the maxilla in a 15 years old female. The patient was subjected to a maxillectomy, preserving the orbit floor. The postoperative evolution has been uneventful. The tumor mainly involved the maxillary sinus with extension to the orbit wall and osseous palate. Very few cases of aneurysmal bone cysts of the maxilla have been reported in the literature.