Neoplasia Practice Questions

Q: Which of the following genes promote epithelial-mesenchymal transition and are important metastatic genes in epithelial tumors?

Both SNAIL and TWIST. **Explanation:** The correct answer is **Both SNAIL and TWIST**. **1. Understanding Epithelial-Mesenchymal Transition (EMT):** EMT is a biological process where polarized epithelial cells lose their adhesion and apical-basal polarity, gaining a migratory mesenchymal phenotype. This is a critical step in the **invasion-metastasis cascade**. * **Mechanism:** The hallmark of EMT is the **downregulation of E-cadherin** (the "glue" that holds epithelial cells together) [1]. * **Role of SNAIL and TWIST:** These are specific transcription factors that act as master regulators of EMT [1]. They directly bind to the promoter of the E-cadherin gene (*CDH1*) and **repress its transcription** [1]. By suppressing E-cadherin and upregulating mesenchymal markers like Vimentin and Smooth Muscle Actin, they enable tumor cells to detach from the primary mass, breach the basement membrane, and enter the circulation. **2. Why other options are incorrect:** * **MYC (Option A):** While *MYC* is a potent proto-oncogene involved in cell cycle progression, metabolism, and transformation, it is not a primary driver of EMT. It typically promotes proliferation rather than the specific phenotypic switch to a mesenchymal state. **3. High-Yield Clinical Pearls for NEET-PG:** * **E-cadherin:** Loss of E-cadherin is the "molecular signature" of EMT and is characteristically seen in **Lobular Carcinoma of the Breast** and **Diffuse Gastric Cancer** (Signet ring cell type). * **TGF-β:** This cytokine is a major inducer of EMT in the tumor microenvironment [1]. * **Metastasis:** EMT is reversible. Once the tumor cell reaches a distant site, it undergoes **MET (Mesenchymal-Epithelial Transition)** to form a secondary colony. * **Transcription Factors:** Remember the triad of EMT regulators: **SNAIL, SLUG, and TWIST.** **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 317-318.

Question 1

Which structure is NOT typically found in the anterior mediastinum?

Accepted Answer

Neurofibroma

Answer

Teratoma

Answer

Thymic tumors

Answer

Thyroid tumors

Question 2

Which of the following genes promote epithelial-mesenchymal transition and are important metastatic genes in epithelial tumors?

Accepted Answer

Both SNAIL and TWIST

Answer

MYC

Answer

SNAIL

Answer

TWIST

Question 3

Defects in DNA repair are associated with an increased risk of malignancy in which of the following conditions?

Accepted Answer

Xeroderma pigmentosum

Answer

Ichthyosis

Answer

Mosaicism

Answer

None of the above

Question 4

Which of the following is NOT a criterion for staging of a disease?

Accepted Answer

Degree of differentiation

Answer

Size of primary tumor

Answer

Extension to lymph nodes

Answer

Metastases

Question 5

Which of the following is not a carcinogenic virus?

Accepted Answer

Molluscum contagiosum

Answer

Hepatitis B

Answer

Hepatitis C

Answer

HPV

Question 6

Which of the following statements regarding Kaposi's Sarcoma is true?

Accepted Answer

Has increasing incidence among AIDS patients.

Answer

Does not occur in non-HIV positive persons.

Answer

No gastrointestinal bleeding.

Answer

Uncommon among homosexual HIV positive individuals.

Question 7

Which of the following are required for normal cell growth?

Accepted Answer

All of the above

Answer

Protooncogenes

Answer

Tumor suppressor genes

Answer

DNA repair genes

Question 8

The Nottingham histologic score does not include which of the following?

Accepted Answer

Presence or absence of metastases

Answer

Tubule formation

Answer

Nuclear pleomorphism

Answer

Mitotic rate

Question 9

Which type of DCIS typically presents as a palpable abnormality?

Accepted Answer

Paget's disease of the nipple

Answer

Comedocarcinoma

Answer

Non-comedo DCIS

Answer

None of the above

Question 10

What is true about proto-oncogenes?

Accepted Answer

They are normally involved in cell cycle proliferation.

Answer

They produce tumors.

Answer

They are normally involved in the suppression of tumor production.

Answer

Mutation of proto-oncogenes causes cancer.

Neoplasia — MCQs

Neoplasia — MCQs

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