Gene of the month:<i>KRAS</i>

Chetty, Runjan; Govender, Dhirendra

doi:10.1136/jclinpath-2013-201663

Cited by 27 publications

(26 citation statements)

References 24 publications

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“…It is known to regulate various cellular functions, including proliferation, survival, growth, migration, differentiation and cytoskeletal dynamics [2][3][4] (Figure 1). Not coincidentally, increased activities of all of these processes are required by tumor cells to promote tumor growth.…”

Section: Ras Gtpase Overviewmentioning

confidence: 99%

Section: Ras Gtpase Overviewmentioning

confidence: 99%

“…Constitutive activation of the RAS protein, in which RAS is unable to hydrolyze GTP, leads to cancer and other diseases [1,9,12] . Activating RAS mutations have been observed in 30% of human tumors [2,13] ; KRAS is the most commonly mutated isoform, mutated in 25%-30% of human cancers [3,13] . KRAS mutations are dominant in colorectal cancer (40%-45%), non-small cell lung cancer (NSCLC) (15%-40%) and pancreatic carcinoma (69%-95%) [2,3] and are associated with poor patient outcomes and treatment responses in these malignancies [2,3] .…”

Section: Wwwnaturecom/aps Guin S Et Almentioning

confidence: 99%

“…Not coincidentally, increased activities of all of these processes are required by tumor cells to promote tumor growth. Activating oncogenic RAS mutations lead to treatment resistance in various tumor models and poor patient outcomes [3,[5][6][7][8][9] . Three human RAS genes have been identified: HRAS, KRAS, and NRAS [1,2] .…”

mentioning

confidence: 99%

“…KRAS exists as two isoforms, 4A and 4B, which are generated by alternative exon splicing [10] . These different RAS genes are well known to have differential cellular specificities and intrinsic transforming potentials [3,4,10] .In normal cells, RAS proteins act as molecular switches for critical cellular functions. RAS proteins are activated by upstream receptors such as receptor tyrosine kinases * To whom correspondence should be addressed.…”

mentioning

confidence: 99%

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The RAS-RAL axis in cancer: evidence for mutation-specific selectivity in non-small cell lung cancer

Guin

Theodorescu

2015

Acta Pharmacol Sin

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Activating RAS mutations are common in human tumors. These mutations are often markers for resistance to therapy and subsequent poor prognosis. So far, targeting the RAF-MEK-ERK and PI3K-AKT signaling pathways downstream of RAS is the only promising approach in the treatment of cancer patients harboring RAS mutations. RAL GTPase, another downstream effector of RAS, is also considered as a therapeutic option for the treatment of RAS-mutant cancers. The RAL GTPase family comprises RALA and RALB, which can have either divergent or similar functions in different tumor models. Recent studies on non-small cell lung cancer (NSCLC) have showed that different RAS mutations selectively activate specific effector pathways. This observation requires broader validation in other tumor tissue types, but if true, will provide a new approach to the treatment of RAS-mutant cancer patients by targeting specific downstream RAS effectors according to the type of RAS mutation. It also suggests that RAL GTPase inhibition will be an important treatment strategy for tumors harboring RAS glycine to cysteine (G12C) or glycien to valine (G12V) mutations, which are commonly found in NSCLC and pancreatic cancer. Review RAS GTPase overviewRAS is the most extensively studied GTPase [1] . It is known to regulate various cellular functions, including proliferation, survival, growth, migration, differentiation and cytoskeletal dynamics [2][3][4] (Figure 1). Not coincidentally, increased activities of all of these processes are required by tumor cells to promote tumor growth. Activating oncogenic RAS mutations lead to treatment resistance in various tumor models and poor patient outcomes [3,[5][6][7][8][9] . Three human RAS genes have been identified: HRAS, KRAS, and NRAS [1,2] . These encode the related proteins HRAS, KRAS and NRAS, respectively, of 189 amino acids in length [1,4] . KRAS exists as two isoforms, 4A and 4B, which are generated by alternative exon splicing [10] . These different RAS genes are well known to have differential cellular specificities and intrinsic transforming potentials [3,4,10] .In normal cells, RAS proteins act as molecular switches for critical cellular functions. RAS proteins are activated by upstream receptors such as receptor tyrosine kinases * To whom correspondence should be addressed. E-mail dan.theodorescu@ucdenver.edu Received 2014-08-07 Accepted 2014-10-30 Figure 1. RAS GTPase activation and downstream signaling. The cartoon shows the mechanism of RAS GTPase activation by upstream stimuli and numerous downstream effectors stimulated by activated RAS. RAS regulates critical cellular functions through these effectors. Constitutive RAS activation due to mutations leads to protumorigenic signaling through these effectors.

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Section: Ras Gtpase Overviewmentioning

confidence: 99%

Section: Ras Gtpase Overviewmentioning

confidence: 99%

Section: Wwwnaturecom/aps Guin S Et Almentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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The RAS-RAL axis in cancer: evidence for mutation-specific selectivity in non-small cell lung cancer

Guin

Theodorescu

2015

Acta Pharmacol Sin

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Medullary carcinoma of the colon: can the undifferentiated be differentiated?

Fiehn¹,

Grauslund²,

Glenthøj³

et al. 2014

Virchows Arch

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Medullary carcinoma of the colon is a rare variant of colorectal cancer claimed to have a more favorable prognosis than conventional adenocarcinomas. The histopathologic appearance may be difficult to distinguish from poorly differentiated adenocarcinoma. The study aimed to evaluate the diagnostic interobserver agreement and to characterize the immunohistochemical and molecular differences between these two subgroups. Fifteen cases initially classified as medullary carcinoma and 30 cases of poorly differentiated adenocarcinomas were included. Two pathologists reviewed the slides independently without knowledge of the original diagnosis and subgrouped the tumors into the two entities. Agreement was reached in 31 of 45 cases (69 %) with kappa = 0.32. An extensive immunohistochemical panel was performed, and KRAS, NRAS, and BRAF mutational status was assessed. Of the 31 cases with diagnostic agreement, the expression of only MLH-1 along with corresponding expression of PMS-2 differed significantly (p = 0.04). A high rate of BRAF mutations was detected in both subgroups without significant differences. Expression of MLH-1 was superior in dividing the tumors into two separate entities with significant differences in CK20 (p = 0.005) expression and in the rate of BRAF mutations (p = 0.0035). In conclusion, medullary carcinomas of the colon are difficult to discriminate from poorly differentiated adenocarcinoma even with the help of immunohistochemical and molecular analyses. This raises the question whether these morphological subtypes should be maintained or whether an alternative classification of poorly differentiated colorectal adenocarcinomas based on MLH-1 status rather than morphology should be suggested.

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