Shorter telomeres and high telomerase activity correlate with a highly aggressive phenotype in breast cancer cell lines.

Maintenance of telomere length is one function of human telomerase that is crucial for the survival of cancer cells and cancer progression. Both telomeres and telomerase have been proposed as possible biomarkers of cancer risk and cancer invasiveness; however, their clinical relevance is still under discussion. In order to improve our understanding of the relationship between telomere length and telomerase activity with cancer invasiveness, we studied telomere length as well as telomerase levels, activity, and intracellular localization in breast cancer cell lines with diverse invasive phenotypes. We found an apparently paradoxical coincidence of short telomeres and enhanced telomerase activity in the most invasive breast cancer cell lines. We also observed that hTERT intracellular localization could be correlated with its level of activity. There was no association between human telomerase reverse transcriptase (hTERT) protein expression levels and invasiveness. We propose that simultaneous evaluation of these two biomarkers-telomere length and telomerase activity-could be useful for the assessment of the invasive capacity and aggressiveness of tumor cells from breast cancer patients.

Regulation of p14ARF expression by HPV-18 E6 variants.

A common causative agent for uterine cervical cancer is the human papillomavirus type 18 (HPV-18) which has three phylogenic variants: Asian-Amerindian, European, and African. Each variant shows significant molecular differences in the E6 gene. E6 oncoprotein is a negative regulator of tumor suppressor protein p53, hence, this oncoprotein indirectly regulates the expression of tumor-suppressor p14(ARF) . p14(ARF) and p16(INK4A) genes are overexpressed in--and have been proposed as markers for--HPV-related cervical cancer. In order to dissect the role of E6 on the regulation of p14(ARF) expression, separating it from that of other intervening factors, transfection of E6 variants to MCF-7 cells was performed, assessing cDNA transcript levels by RT-PCR, whereas p14(ARF) and p53 expression were evaluated by immunocytochemistry and Western blot. E6 transfected cells differentially expressed transcripts of two molecular forms: E6 and E6*. The ratio of these two forms varied with the transfected E6 variant. With the Asian-Amerindian variant, the ratio was E6 > E6*, whereas with the European and the African the ratio was E6* > E6. As expected with the E6* construct, E6* transcripts were solely observed. In addition, when E6 > E6* and p53 expression was low, p14(ARF) was high and when E6* > E6 and p53 expression was high, p14(ARF) was low. In conclusion, each E6 variant distinctively affects p53 levels and consequently p14(ARF) expression, finding that could be related with the differences in oncogenic effect of infection with the diverse high-risk HPV variants.

Nuclear co-expression of p14ARF and p16INK4A in uterine cervical cancer-derived cell lines containing HPV.

The Papanicolaou test (Pap) has been responsible for a significant reduction of cervical cancer-related morbimortality. In order to increase its sensitivity and specificity new markers have been studied and incorporated to cytological and histological methods for diagnosis for cervical cancer, such as p16INK4A that has been considered the immunocytochemical marker of choice for detection of HPV related cancers. We considered that p14ARF could be a complementary marker in order to improve the accuracy of cytological diagnosis because its genetic proximity to p16INK4A. We performed a systematic analysis of several putative cervical cancer markers in order to evaluate their performance in the detection of malignancy, in comparison with p16INK4A and p14ARF, using immunocytochemistry (ICC), immunofluorescence (IF) and Western blot analyses. Most markers were non-specific and could not discriminate HPV infected cancer cell lines from other non HPV malignant. In contrast, nuclear co-expression of p16INK4A and p14ARF was observed only in HPV-transformed cancer cell lines. Notably, in C-33A cervical cancer cells (HPV negative), p14ARF was present in the nucleoli, but p16INK4A was conspicuously absent from the nuclei of these cells. We conclude that both markers; p16INK4A and p14ARF are complementary and should be evaluated jointly in order to improve the accuracy of cytological diagnosis of cervical cancer.

[Proteases in cancer progression]. / Las proteasas en la progresión neoplásica.

Invasion and metastasis are the most important events in cancer progression. In these two phases, several molecules are implicated and have been long associated with several forms of cancer. Proteases play a critical role not only in tumor cell invasion, but also in the earliest stages of carcinogenesis and its associated changes: angiogenesis and metastasis. Aside from their ability to degrade the extracellular matrix, facilitate invasion and metastasis, proteases target a great variety of substrates that favor or inhibit cancer progression: b-FGF, HGF, VEGF, cell death receptors, cistatin-C, galectin, procollagen, and other proteases. Proteases are also signaling molecules that modulate other molecules by underlying pathways in addition to their degradative role. Proteases form interconnected cascades, circuits and networks that bring about the tumor's potential for malignancy. Although, proteases are regulated by diverse molecules, it is known that tumoral and stromal cells secrete several biological molecules, including cytokines and chemokines that directly or indirectly regulate the protease-expression within the tumor's microenvironment. The present review briefly summarizes some of the major aspects associated with the role of proteases in cancer progression.

Las proteasas en la progresión neoplásica / Proteases in cancer progression

La invasión y la metástasis son los eventos más importantes en la progresión del cáncer, en los cuales están implicadas muchas moléculas, entre ellas, las proteasas. Éstas desempeñan un papel importante en etapas tempranas de la carcinogénesis, en la invasión, en fenómenos asociados como la angiogénesis y en la metástasis, principalmente por su capacidad para degradar componentes de la matriz extracelular, aunque sus sustratos son de naturaleza diversa: citocinas, quimiocinas, factores de crecimiento (b- FGF, HGF, VEGF) y de muerte celular, cistatina-C, galectina, procolágena y otras proteasas, que pueden favorecer o inhibir la progresión neoplásica. Las proteasas son también moléculas de señalización que modulan a otras moléculas; forman cascadas, circuitos e incluso redes, que en conjunto determinan parte del potencial maligno. Se sabe que tanto la célula tumoral como las del estroma secretan diversos factores que regulan directa e indirectamente la expresión de proteasas en el microambiente tumoral. Esta revisión proporciona un panorama breve y actualizado sobre la participación de las proteasas en la progresión neoplásica.

Invasion and metastasis are the most important events in cancer progression. In these two phases, several molecules are implicated and have been long associated with several forms of cancer. Proteases play a critical role not only in tumor cell invasion, but also in the earliest stages of carcinogenesis and its associated changes: angiogenesis and metastasis. Aside from their ability to degrade the extracellular matrix, facilitate invasion and metastasis, proteases target a great variety of substrates that favor or inhibit cancer progression: b-FGF, HGF, VEGF, cell death receptors, cistatin-C, galectin, procollagen, and other proteases. Proteases are also signaling molecules that modulate other molecules by underlying pathways in addition to their degradative role. Proteases form interconnected cascades, circuits and networks that bring about the tumor's potential for malignancy. Although, proteases are regulated by diverse molecules, it is known that tumoral and stromal cells secrete several biological molecules, including cytokines and chemokines that directly or indirectly regulate the protease-expression within the tumor's microenvironment. The present review briefly summarizes some of the major aspects associated with the role of proteases in cancer progression.

Determinación de la ploidia del ADN por citofotometría en líquidos pleural y abdominal y su correlación con diagnóstico citológico convencional (Estudio de 40 casos) / (DNA ploidym image cytometry and cytology of pleural and abdominal fluids)

Se realiza un análisis prospectivo de 40 líquidos corporales, 22 abdominales y 18 pleurales, recibidos en un lapso de 5 meses. Se estableció una correlación entre el exámen citológico de rutina y la ploidia del ADN, determinada por citofotometría. De los 25 casos clasificados citológicamente como benignos, 21 fueron diploides y 4 aneuploides; sólo uno de estos últimos al revaluarse la citología fue considerado como no neoplásico, los otros 3 fueron falsos negativos. De los 15 casos considerados citológicamente como malignos, 3 fueron diploides y sólo uno de estos fue un falso positivo por citología. Los otros 2 fueron: 1 linfoma y 1 mesotelioma, mismos que con gran frecuencia pueden ser diploides. La sensibilidad y la especificidad por ambos métodos fueron de 77 y 95 por ciento y de 94 y 95 por ciento respectivamente. De lo anterior concluimos que la Cl nos puede ayudar a detectar aneuploidia en algunos casos diagnosticados en citología como falsos negativos (3 de nuestros casos); pero en algunos casos las células malignas pueden ser diploides (20 por ciento de nuestros casos) y entonces la Cl no nos permitiría detectarlos como malignos y es aquí donde la citología de rutina es indispensable