Direct physical interaction of active Ras with mSIN1 regulates mTORC2 signaling.

BACKGROUND: The mechanistic (or mammalian) target of rapamycin (mTOR), a Ser/Thr kinase, associates with different subunits forming two functionally distinct complexes, mTORC1 and mTORC2, regulating a diverse set of cellular functions in response to growth factors, cellular energy levels, and nutrients. The mechanisms regulating mTORC1 activity are well characterized; regulation of mTORC2 activity, however, remains obscure. While studies conducted in Dictyostelium suggest a possible role of Ras protein as a potential upstream regulator of mTORC2, definitive studies delineating the underlying molecular mechanisms, particularly in mammalian cells, are still lacking. METHODS: Protein levels were measured by Western blotting and kinase activity of mTORC2 was analyzed by in vitro kinase assay. In situ Proximity ligation assay (PLA) and co-immunoprecipitation assay was performed to detect protein-protein interaction. Protein localization was investigated by immunofluorescence and subcellular fractionation while cellular function of mTORC2 was assessed by assaying extent of cell migration and invasion. RESULTS: Here, we present experimental evidence in support of the role of Ras activation as an upstream regulatory switch governing mTORC2 signaling in mammalian cancer cells. We report that active Ras through its interaction with mSIN1 accounts for mTORC2 activation, while disruption of this interaction by genetic means or via peptide-based competitive hindrance, impedes mTORC2 signaling. CONCLUSIONS: Our study defines the regulatory role played by Ras during mTORC2 signaling in mammalian cells and highlights the importance of Ras-mSIN1 interaction in the assembly of functionally intact mTORC2.

Molecular Alterations and Expression Dynamics of LATS1 and LATS2 Genes in Non-Small-Cell Lung Carcinoma.

Large tumor suppressor (LATS) is an important member of the Hippo pathway which can regulate organ size and cell proliferation. However, very little is known about the expression and clinical significance of LATS in lung cancer especially from this part of the world. We elucidated the frequency of LATS1 &LATS2 promoter hypermethylation (by methylation-specific PCR) and expression (by real-time PCR) in sixty nine (n = 69) Non-Small Cell Lung Cancer (NSCLC) patients and their corresponding normal lung tissue samples. We found promoter hypermethylation frequencies of LATS1 & LATS1to be 66.66% (46/69) and 71% (49/69) in NSCLC tissues. Decreased LATS1 & LATS2 mRNA expression was found in 55% and 66.66% of NSCLC patients. The LATS1 mRNA expression was significantly higher in normal lung tissues. Also, the mRNA levels of LATS1 and LATS2 NSCLC tissues with hypermethylation were significantly lower. Multivariable analysis confirmed that LATS1 under expression increased the hazard of death after adjusting for other clinicopathological factors. Importantly, the loss of LATS1 mRNA expression was associated with overall short survival. LATS1 is an independent prognostic factor and may play an important role in NSCLC progression and may serve as a novel therapeutic target of NSCLC.

TAZ is an independent prognostic factor in non-small cell lung carcinoma: Elucidation at protein level.

BACKGROUND: Hippo-LATS pathway is involved in regulating multiple phenotypes. TAZ (transcriptional co-activator with PDZ-binding motif) is a prominent proto-oncogene of this developmental pathway. Elevated TAZ expression has been observed in many cancers including Non-Small Cell lung cancer (NSCLC). OBJECTIVE: We elucidated the frequency of protein expression of TAZ gene in NSCLC patients of our population along with its relationship with clinicopathological parameters and determined its prognostic significance concerning survival in patients with resected tumor. METHODS: We looked into the protein expression of TAZ gene in sixty nine (n= 69) cases of NSCLC tissue and their corresponding normal lung tissue samples by western blotting. Kaplan-Meier survival analysis and Cox proportional hazards models were used to estimate the effect of TAZ protein expressionon survival. RESULTS: Here, we found that TAZ protein expression was elevated in 49.27% (34 of 69) of NSCLC tissues as compared to only 13.04% (09 of 69) in normal lung tissues. TAZ protein expression was significantly associated with smoking, positive lymph node status and vascular invasion (P< 0.05). TAZ protein overexpression increased the hazards ratio by 2.6 (P= 0.005) on univariate analysis. Multivariable analysis confirmed that TAZ protein overexpression along with age and lymph node metastasis increased the hazard of death after adjusting for other clinicopathological factors (P< 0.05). Importantly, TAZ protein overexpression was associated with short overall survival and disease-free survival when compared with normal TAZ expression. CONCLUSION: These results indicate that TAZ is an independent prognostic factor and plays an important role in NSCLC progression and may serve as a novel therapeutic target of NSCLC.

Assessment of Correlation between Sweat Chloride Levels and Clinical Features of Cystic Fibrosis Patients.

INTRODUCTION: Cystic Fibrosis (CF) is an autosomal recessive disorder and the incidence of this disease is undermined in Northern India. The distinguishable salty character of the sweat belonging to individuals suffering from CF makes sweat chloride estimation essential for diagnosis of CF disease. AIM: The aim of this prospective study was to elucidate the relationship of sweat chloride levels with clinical features and pattern of CF. MATERIALS AND METHODS: A total of 182 patients, with clinical features of CF were included in this study for quantitative measurement of sweat chloride. Sweat stimulation and collection involved pilocarpine iontophoresis based on the Gibson and Cooks methodology. The quantitative estimation of chloride was done by Schales and Schales method with some modifications. Cystic Fibrosis Trans Membrane Conductance Regulator (CFTR) mutation status was recorded in case of patients with borderline sweat chloride levels to correlate the results and for follow-up. RESULTS: Out of 182 patients having clinical features consistent with CF, borderline and elevated sweat chloride levels were present in 9 (5%) and 41 (22.5%) subjects respectively. Elevated sweat chloride levels were significantly associated with wheeze, Failure To Thrive (FTT), history of CF in Siblings, product of Consanguineous Marriage (CM), digital clubbing and steatorrhoea on univariate analysis. On multivariate analysis only wheeze, FTT and steatorrhoea were found to be significantly associated with elevated sweat chloride levels (p<0.05). Among the nine borderline cases six cases were positive for at least two CFTR mutations and rest of the three cases were not having any mutation in CFTR gene. CONCLUSION: The diagnosis is often delayed and the disease is advanced in most patients at the time of diagnosis. Sweat testing is a gold standard for diagnosis of CF patients as genetic mutation profile being heterozygous and unlikely to become diagnostic test.